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H aa ath be aa ea boys Suhr att f mp UR iPr Mert he Ei Bt lms lriro EEN eb S bac PEAY ) oe ‘ EPP Een Sry EMS EP arbt Ce BRA Menbeyd teers rop tad : ' ine ROME Cpe ee tren erty er tpt ree Sih Benes Fire bay inet icy ‘ we bie ds dshd Gera daikyeddekrbesedl sibtkedonaba tense , Phere Mea rebet i eee heir Pert 5 eres "| ‘ ae Pret pep ert ieanertart Pyrer abi eryrt ) Sb urtbIN Pf rere ] , f ‘ P| ts 7 J s u Cy » rd Creer es " rere eine hy Parr ube Mat eh rt " Hai , ‘ Brera ey Chea at at stg ier ett } f f here) , rer er ens ret tr " i ‘ i ' TE terre err erirerer rs tC too : ’ a) 4 L * at M4 aes Oe el bee a , I y APRS Br ur ae Beret ee ce erent irae ' LPP Par ye erent F ri oct Pr earl es Per teBi hap pt a Mri i iG , haben ie sao Cures eer n erie ; ere brarer tree Weer ira heer reer Crete eke te er Ci Pereeere ‘ " ' ‘' f , et Shabbir bret eobran! corre peer ret ' err ere rn wre SECS AEE f , eee Wee ; t , ‘ ERENCES Cert ret Peter ey tet Porro er er eae y f rere eCee ast ee Bree eet | renee Pree ere ae et Poet te , " 4 re ra a erErhe Beer: ePerurisnreoceurer tr erer ty somPirer hr areribrer or py keine r brkpe fats 4 " " ’ Perera) et eee ereretertryerenn for etn ott rer , on ch ere enr rey Cee eC OC RUE Sie errr aoe y f peer : ee yf ateoten s f ST Rer Re teh , ib : " tr es paver er er er TT SU RC ACRE EL} Asacasasdauenen ines 7 aL 4 a t c , i] al a a ’ shbdebe ee piled A. beh. ’ Fj ‘ , ah sept ad " ete ERE Retr ee eran " yh bai hie Cheer eeey perry re Mert] Reiman rarer er De Peretererer yen " ‘ , f" PePEreCer enw arent Mructr et irer my sine Cet ecar meer Beer ener Wr itet orn ny urtr er Ernin ' " Wal Brae Hear bei e r Rael ae eee on Wiehe " nf ‘ fi at Paar Dares hont y erie ren ernest er es Perrone tier bt y ere eon tea) Ere area: ee pede Sod Wa dery lorem , , eh rr er peee ttt Maurer BpEP area itr bi , Per yee rere " peer re. ere bt Yr) cr ereren ern ts Oye ‘ " f Lae e M , aaa Pere eroriribnel penn menreckr sehen keer bt it brs - ‘skle oP er Meet + 4 rere Mente oor er Peles coer ty n mer Pris ee eran iy Tee POICPG PMs tt Pa PRE Rudl bokc hunt tock ei dc htcke eu pehaetet ve PPLE rSrer Serer ee SMITHSONIAN INSTITUTION MUSEUM OF NATURAL HISTORY = UNITED STATES NATIONAL MUSEUM BULLETIN 275 The Rodents of Libya Taxonomy, Ecology and Zoogeographical Relationships GARY L. RANCK Curator, Mammal Identification Service Division of Mammals, U.S. National Museum SMITHSONIAN INSTITUTION PRESS WASHINGTON, D.C. 1968 Publications of the United States National Museum The scientific publications of the United States National Museum include two series, Proceedings of the United States National Museum and United States National Museum Bulletin. In these series are published original articles and monographs dealing with the collections and work of the Museum and setting forth newly acquired facts in the field of anthropology, biology, geology, history, and technology. Copies of each publication are distributed to libraries and scientific organizations and to specialists and others interested in the various subjects. The Proceedings, begun in 1878, are intended for the publication, in separate form, of shorter papers. These are gathered in volumes, octavo in size, with the publication date of each paper recorded in the table of contents of the volume. In the Bulletin series, the first of which was issued in 1875, appear longer, separate publications consisting of monographs (occasionally in several parts) and volumes in which are collected works on related subjects. Bulletins are either octavo or quarto in size, depending on the needs of the presentation. Since 1902, papers relating to the botanical collections of the Museum have been published in the Bulletin series under the heading Contributions from the United States National Herbarium. This work forms number 275 of the Bulletin series. Frank A. TayYLor Director, United States National Museum U.S. GOVERNMENT EEENTING OFFICE WASHINGTON : For sale by the Superintendent of Documents, U.S. Government it Printing Office Washington, D.C. 20402 - Price $1.50 (paper cover) Contents Page Acknowledgments 1 Introduction . ; 3 Physical description of howe: 6 General features 6 The coastal plain . 7 The coastal escarpment . 7 Pre-Saharan or steppe . 1 Hamadas 8 Sand seas 9 Serirs . Mode et eine eee ee pe ees eo ee eS cee aye he ere 9 Hesh=feshvers "ie <, Ba. ws Ss ed Bn Oe SE ee we ee 10 Depressions .. . Rye ve LS, ness ee ve de ee eo 10 Mountainous areas GF thie atetiow ne See Sl es oe eas ee Se 10 Whew yrensican Plateau: 2. & © 2.<.3 24 4 se ae & ew oe 11 ihe irmpolttanisn Gebel. « S2INo lar te) 62 El] Gatrun (24° 57 N, 14° 39 E) 76 Ghat, 20 km N (25° 08 N, 10° 1) E) 75 Goddua, 26 km N (26° 38 N, 14° 25 E) 66 roddua (26° 25 N, 14° 19 E) 67 Meseguin (26° 09 N, 14° 58 E) 69 Murzuch, 28 km E (25° 55 N, 14° 12 E) 2 Murzuch (252755 Na i32. 55) 5) io Sebha (27° N, 14° 27 E) 64 Serdeles, 55 km SSW (25° 19 N, 10° 15 E) 74 Temenhint, 30 km NE Sebha (27° 13 N, 14° 38 E) 63 Traghen (25° 59 N, 14° 26 EB) a Ubari, 75 km W (26° 25 N, 12° 02 E) 68 RODENTS OF LIBYA 69 Family Cricetidae Subfamily Microtinae Genus Microtus Schrank Microtus mustersi Hinton Microtus musterst Hinton, Ann. Mag. Nat. Hist., ser. 9, vol. 18, p. 305, September 1926 (Merj [= Barce], Cyrenaica). GENERAL DISTRIBUTION OF SPECIES. Libya, on the Cyrenaican Plateau and adjacent coastal plain. SPECIMENS EXAMINED. Six, from Cyrenatica: 10 km SW El Faidia, 1 (skin, skull, and skeleton); Merg (=Barce), 2 (BM; 1 skin only); 5 km W Tocra, 3. PUBLISHED RECORDS IN Lispya. CyrENAICA: Barce (Hinton, 1926). LIBYA KILOMETERS Microtus mustersi Ficure 4.—Distribution of Microtus musterst. 70 U.S. NATIONAL MUSEUM BULLETIN 275 MEASUREMENTS. The measurements of two immature males, 325019 and 325021, and of an adult male, 325020, from 5 kilometers west of Tocra, Cyrenaica, are respectively: Total length 131, 130, 130; length of tail 30, 25, 31; length of hind foot 18, ?, 18; length of ear 11, 10, 12; condyloincisive length of skull 24.6, 25.8, 26.5; greatest breadth across zygomatic arches 14.4, 14.5, 15.9; length of nasals 6.7, 6.9, 6.7; least interorbital breadth 3.7, 3.9, 3.8; crown length of upper molariform toothrow 5.9, 6.4, 6.4; greatest breadth across braincase 11.4, 11.7, 12; length of incisive foramina 4.4, 4.5, 4.5. Dracnosts. Entire dorsum uniformly colored Buckthorn Brown, becoming slightly paler on flanks and sides and forming a distinct con- trast with the white-tipped hairs of the venter; all hairs of dorsum and venter Plumbeous basally; pinnae of ears short and inconspicuous, Prout’s Brown, sparsely haired, and with several long brownish hairs partially covering ventrolateral surfaces; eye ring absent; vibrissae relatively short and fine and composed of both light and dark individ- ual hairs; dorsal surfaces of forelegs, hindlegs, and feet light tan; ventral surfaces of fore and hind feet naked with prominent carpal and palmar tubercles; front feet with four functional digits with claws, the first digit reduced to a rudimentary tubercle; hind feet with five func- tional digits with claws; tail noticeably short and distinctly bicolored dark brown above and buff below. Skull: Medium in size; compact and angular; zygomata heavy with a uniform lateral curvature; inter- orbital breadth markedly constricted; suprameatal portion of auditory bulla enclosed by processes of the supraoccipital and temporal bones; parietal ridges markedly reduced and inconspicuous; interparietal transversely elongated; nasals short and moderately flaring anteriorly ; upper incisors markedly prognathous; dorsal margin of foramen magnum with prominent notch; audital portions of auditory bullae conspicuously inflated ventrally; pterygoid processes and external pterygoid fossae heavily fenestrated; hamulae large and applied to anteromedial portions of auditory bullae; molariform toothrows long and individual teeth with prominent inner and outer salient angles; anterior palatine foramina relatively short and narrow; posterior palatine canals small and inconspicuous. Comparisons. Compared to representatives of Microtus guenthert Danford and Alston from the Valley of Ali Bey Dere, near Piringcikoy, 16 kilometers west of Istanbul, Turkey, the specimens from Libya differ strikingly in having markedly smaller, less angular skulls, nar- rower rostra, more ventrally inflated auditory bullae, more fragile zygomata, narrower basioccipitals, markedly smaller incisors, and the third molar nearly as large as the second, rather than being signifi- cantly smaller as in guenther?. In external characters, the specimens RODENTS OF LIBYA TA from Libya are significantly larger, have less hair on the ears, are more brightly colored dorsally (Buckthorn Brown as opposed to Snuff Brown), have a greater suffusion of white ventrally, more orangish- buff on the dorsal surfaces of the fore and hind feet, and have more prominently bicolored tails. In M. mustersi the tail is markedly longer than the hind foot and almost one fourth the length of the head and body, rather than only slightly larger than the hind foot and one-fifth the length of the head and body asin M. guentheri, and the sole of the hind foot is naked for a ereater distance posterior to the base of the toes. In the number of palmar and plantar pads and in the pattern and number of the molar prisms and reentrant angles, the Libyan speci- mens resemble M. guentherd and indicate relationship with the latter species. Remarks. Hinton (1926) described MM. mustersi as a species distinct from Microtus philistinus Thomas of Palestine. According to Hinton, M. mustersi is closely allied to M. philistinus, but differs in slightly darker (less grayish) dorsal color, slightly narrower choanae, slightly smaller auditory bullae, less reduction of the third molar posteriorly, and less salient temporal ridges with a wider interval between them. Hinton regarded these differences as somewhat tenuous but stated that “craniologically”’ the specimens representing both M. mustersi and M. philistinus, and upon which his comparisons are based, were all subadult and that fully adult specimens probably would show more marked differences. Ellerman and Morrison-Scott (1951) regarded M. mustersi and M. philistinus as conspecific and relegated them both to subspecific rank under M. quentheri. Toschi (1954) also considered AZ. mustersi as a subspecies of MM. guentheri. I agree with Ellerman and Toschi in regarding M. mustersi as a member of the “MM. guentherv” group but feel that other morphological differences between the two are too great to suggest conspecificity, and here MM. mustersi is regarded as a species distinct from M. guentheri. Hinton’s description of Microtus mustersi from Cyrenaica in 1926 constituted the first record of occurrence of a microtine rodent for the African continent, even though members of this group were widespread throughout Europe and Asia. The type series of MZ. mustersi obtained by Chaworth-Musters in 1926 from Barce, a specimen collected by H. W. Setzer in 1955 from 10 kilometers southwest of El Faidia, and the three specimens that I obtained from 5 kilometers west of Tocra are all from Cyrenaica and constitute the only known representatives of the subfamily Microtinae in Libya. 2 U.S. NATIONAL MUSEUM BULLETIN 275 All specimens from Cyrenaica are either topotypes or near topotypes of M. mustersi. Those from the coastal plain near Tocra, however, are the farthest from the type locality, but two specimens are clearly immature and are unsuitable for comparative purposes. The third is of questionable adult status but is near or of comparable age to those specimens with which it is being compared from Merg (=Barce) and El Faidia. The specimen from Tocra is identical in color to M. musterst. In cranial characters it resembles rather closely a topotype of M. mustersi from Barce but differs in slightly smaller size of skull and external dimensions, shorter and narrower anterior palatine foramina, slightly smaller pterygoid foramina, and slightly more inflated mastoidal portions of the auditory bullae. From the specimen from near El Faidia, this specimen from near Tocra differs in the same characters as set forth above, except the two specimens are comparable in the length of the anterior palatine foramina. These differences between the voles of the coastal plain and those from the higher slopes of the plateau are too slight to suggest sub- specific differences and indicate that M. mustersi is a monotypic species whose range includes all of the Cyrenaican Plateau and the adjacent coastal plain wherever suitable habitat occurs. EcoLoGicaAL OBSERVATIONS. The three localities in Cyrenaica where voles are known to occur differ markedly in the character of the habitat. The type locality at Barce, according to Hinton (1926), is at an altitude of 300 meters and in a basin of interior drainage about 20 miles from the coast. Microtus inhabited open burrows with well marked “runs” in the cornfields. The ground was described as being “hard-baked.”’ Near El Faidia, Setzer (1957) described the terrain as hilly and rocky, and a single specimen was obtained from the moist north-facing slope where mosses were growing. This locality is significantly higher in elevation than the Barce Valley and is near the highest point of the Cyrenaican Plateau. In contrast to the high valleys and mountain slopes near Barce and El Faidia, the site near Tocra is located on the lowest level of the coastal plain about one-half kilometer from the Mediterranean Sea. This particular portion of the coastal plain has a dense vegetative cover consisting primarily of interwoven patches of tamarix, large sedges, coarse grasses, and a species of bushlike woody perennial with purple flowers. All these plant-types form rather discrete communities composed almost exclusively of a single dominant type of plant. All voles were taken the same night from the dense understory of the bushlike perennials. Large series of Mus musculus and Gerbillus campestris and several specimens of Crocidura russula Hermann were also obtained from this RODENTS OF LIBYA 73 bushlike growth. The areas of tamarix, sedges, and grasses were trapped intensively, but yields were quite poor. This portion of the coastal plain, with its lush and profuse vege- tative cover, is not typical of most of the Cyrenaican coastal plain, and probably at these lower elevations voles are of very sporadic and local occurrence. The range of MZ. mustersi, in Libya, therefore prob- ably is largely confined to the higher and more typically montane areas of the Cyrenaican Plateau and the Gebel Achdar, which provide more abundant and continuous habitat. The occurrence of voles in Cyrenaica poses some very interesting zoogeographic problems, particularly since they are not known from coastal Egypt, the only conceivable dispersal route. It is possible that the population of voles in Cyrenaica are relicts from the period when the more boreal climates of the Pleistocene prevailed over North Africa. The Cyrenaican Plateau by virtue of its higher elevation has retained at least a vestige of these boreal elements, whereas the remainder of coastal Africa has become much drier and more sparsely vegetated and no longer contains habitats suitable for voles. Subfamily Gerbillinae Genus Gerbillus Desmarest Lataste (1881, p. 506) divided the genus Gerbillus into two genera, Gerbillus and Dipodillus Lataste, and separated the latter from Gerbillus by the number of plantar pads, the pattern of infolding of enamel on the surfaces of the teeth, and by characteristics of the auditory bullae. According to Lataste, typical members of Gerbillus had one carpal pad and no plantar pads, while representatives of Dipodillus had five carpal and six plantar pads. Lataste used the character of naked feet to separate two species, Gerbillus garamantis Lataste and Gerbillus hirtipes Lataste. Heptner (1937) and Ellerman (1941) suppressed Dipodillus as a full genus. The latter author stated that members of the two genera could not be distinguished by cranial characters and that there was a lack of constancy in the characters used by Lataste to distinguish between the two genera. Later, Wassif (1956) and Setzer (1957) regarded Dipodillus as a subgenus of the older prevailing Gerbillus and used the presence or absence of hair on the hind feet to assign their specimens to the two subgenera. The present author uses this same character to separate the subgenera Dipodillus and Gerbillus, each represented in Libya by four species, 285-134 O—68 6 74 U.S. NATIONAL MUSEUM BULLETIN 275 GL , (MMM » im 9 | | | [ L _t | L 6 7 8 9 10 if 12 13 14 15 Ficure 5.—Statistical comparison of length of nasals of the species of the genus Gerbillus: A, G. amoenus: B, G. aureus; C, G. campestris; D, G. eatoni; E, G. gerbillus; F, G. henleyi; G, G. kaiseri; H, G. pyramidum. For explanation of graphs see Plan of Treatment, p. 62. RODENTS OF LIBYA 75 A 1 4 fi ° 7 oO 3 (fn? c » [wry 9 (wien ¢ D » tr o 1» [er 9 E eo [Ws _ an ° ‘a G ; ¢ mie 0 Q 20 22 24 26 28 30 32 34 Ficure 6.—Statistical comparison of occipitonasal length of the species of Gerbil/us. Notation remains the same as in figure 5. 76 U.S. NATIONAL MUSEUM BULLETIN 275 A 4 [Is 1 (mf) ° B yn [) s 1 [ear] ? c » [Mr ¢ o _[ fr] ° D 1 [Mls 21 nga ? E 21 Cio 43 oan ? 7 8 9 10 11 12 Ficure 7.—Statistical comparison of length of auditory bulla of the species of Gerbillus. Notation remains the same as in figure 5. RODENTS OF LIBYA Fire 15 20 25 30 38 Ficure 8.—Statistical comparison of length of hind foot of the species of Gerbillus. Notation remains the same as in figure 5. 78 U.S. NATIONAL MUSEUM BULLETIN 275 A ;__ [ofan + u fi 6° Ficure 9.—Statistical comparison of least intergrbital breadth of the species of Gerbillus. Notation remains the same as in figure 5. A nr) nie B a 1 wom 9 C g_CW7 » [wl 9 p ye . im 9 Figure 10.—Statistical comparison of upper molariform toothrow of the species of the subgenus Gerbillus: A, G. aureus; B, G. eatoni; C, G. gerbillus; D, G. pyramidum. RODENTS OF LIBYA 79 36 C - # Gerbillus aureus 35 O O Gerbillus pyramidum OCCIPITONASAL LENGTH OF SKULL 1 2 3 4 9 6 CROWN LENGTH OF UPPER MOLARIFORM TOOTHROW Ficure 11.—Comparison of crown length of upper molariform toothrow relative to oc- cipitonasal length of Gebillus aureus and Gerbillus pyramidum, SO U.S. NATIONAL MUSEUM BULLETIN 275 A 1 (ifn 4 (an? 3 4 Ficure 12.—Statistical comparison of crown length of upper molariform toothrow of the species of the subgenus Dipodillus: A, Gerbillus amoenus; B, G. campestris; C, G. henleyi; D, G. katsert. RODENTS OF LIBYA S]1 95 9; : 85 * 80 = LENGTH OF TAIL * * 75 * 70 65 @ Gerbillus henleyi se Gerbillus kaiseri 65 70 75 80 85 90 LENGTH OF HEAD AND BODY Figure 13.—Comparison of length of tail relative to length of head and body of Gerbillus henleyt and Gerbillus kaisert. 82 U.S. NATIONAL MUSEUM BULLETIN 275 O Gerbillus henleyi *% Gerbillus kaiseri OCCIPITONASAL LENGTH OF SKULL 6 7 8 9 10 LENGTH OF AUDITORY BULLA Ficure 14.—Comparison of length of auditory bulla relative to occipitonasal length of Gerbillus henleyt and Gerbillus katsert. RODENTS OF LIBYA 83 * 32 x O Gerbillus amoenus * * i i oe Gerbillus campestris eo * ig 31 * ag * * * x* OCCIPITONASAL LENGTH OF SKULL 8 9 10 11 12 13 LENGTH OF AUDITORY BULLA Ficure 15.—Comparison of length of auditory bulla relative to occipitonasal length of Gerbillus amoenus and Gerbillus campestris. 84 U.S. NATIONAL MUSEUM BULLETIN 275 the former consisting of G. amoenus, G. campestris, G. henleyr, and G: kaiseri and the latter composed of G@. aureus, G. eatoni, G. gerbillus, and G. pyramidum. Without doubt, gerbils are the most variable morphologically and the most ecologically tolerant of all the Libyan rodents. They have adapted to practically every available environmental situation. The ability of these gerbils to exploit such a wide array of ecological opportunities indicates a broad genetic constitution. This marked adaptability has enabled them to occupy a vast geographic range in Libya and has contributed to the maintenance of a common mor- phological pattern among the widely scattered populations. Owing to the broad genetic constitution of the species of the genus Gerbillus, there is wide variation in color and in cranial and external characters of the component subspecies. Individual subspecies vary markedly in any given character and generally are distinguished from each other by an aggregate of characters rather than by specific, measurable cranial differences. In gerbils, the usual criteria for recog- nizing subspecies, such as differences in color and cranial and ex- ternal dimensions, are employed, but these differences are usually much more subtle than in other genera of Libyan rodents. Owing to this genetic plasticity in gerbils, the usual 84 to 93 percent rule (1 to 1.5 standard deviations on either side of the mean) for separating the members of two subspecies by a given character is seldom realized, and the percentage of overlap in a character is usually far greater. The ranges of many of the subspecies of gerbils in Libya are con- tiguous, and gene exchange is of common occurrence. These inter- erading populations contain genes from both subspecies and contribute significantly to the maintenance of genetic variability among the populations of gerbils in Libya. In most populations of a given species, and particularly in those subspecies which are geographic isolates, genetic fixation occurs rapidly and trends develop toward morphological distinctness. Key to the Subgenera of Gerbillus Plantar surfaces of hind feet hairy................-.000.eeeeeeeeee- Gerbillus Plantar surfaces of hind feet naked. ............-..- eee eee eee eees Dipodillus RODENTS OF LIBYA 85 Key to the Species of the Subgenus Gerbillus 1. Skull prominently domed; anterior palatine foramina markedly enlarged. G. eatoni Skull not prominently domed; anterior palatine foramina not markedly en- UTE CC nega cat arse eye ar ree Ue Ph ot 2 2. Occipitonasal length of skull less than 30 mm; length of upper molariform Toothnow less titan Am. ses. ose ae ecuane ete rere see G. gerbillus Occipitonasal length of skull usually more than 30 mm; length of molari- form toothrow usually more than 4 mm...............................8 3. Tail with distinct brush; the latter never black............... G. pyramidum Tail without distinct brush; the latter frequently black............G. aureus Gerbillus aureus Setzer Gerbillus pyramidum aureus Setzer, Proc. Biol. Soc. Wash., vol. 69, pp. 179-180, Dee. 31, 1956 (12 km W Zliten, Tripolitania Province, Libya). GENERAL DISTRIBUTION OF SPECIES. Libya; range probably also includes coastal areas of Tunisia. DisTRIBUTION IN LisyaA. Coastal plain and littoral deserts of northern Tripolitania. DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Gerbillus aureus aureus. TRIpOLITANIA: Gebel Nefusa and_ the coastal plain between Azizia and the Gulf of Sirte. Gerbillus aureus favillus. Tripourranta: Vicinity of Sirte; range probably includes much of the coastal plain of the Gulf of Sirte. Gerbillus aureus nalutensis. TRIPOLITANIA: Coastal plain of extreme northwestern Tripolitania. Comparisons. This species can be distinguished from Gerbillus pyramidum, which it most closely resembles, by its markedly smaller skull, smaller body, shorter, less tufted tail, generally darker color, shorter and wider posterior palatine canals, wider anterior palatine foramina, and longer molariform toothrows relative to occipitonasal length. From Gerbillus gerbillus, G. aureus differs in larger body and skull, larger molariform teeth, markedly less tufted tail, larger anterior palatine foramina, more robust skull, heavier zygomata, and generally darker, less orangish dorsal color. Gerbillus aureus can be readily separated from Gerbillus eatoni by its larger body, larger and heavier skull, larger molariform teeth, smaller anterior palatine foramina, longer posterior palatine canals, smaller and less inflated auditory bullae, and markedly more flattened braincase. Remarks. Setzer described Gerbillus pyramidum aureus (= Gerbillus aureus aureus) (1956, p. 179) and Gerbillus pyramidum favillus (=Gerbillus aureus favillus) (1956, p. 180) as new subspecies of G. pyramidum. In naming these new subspecies, he had only topotypical 86 U.S. NATIONAL MUSEUM BULLETIN 275 L | BYA Ley 190 KILOMETERS Gerbillus aureus |. aureus 2. favillus 3. nalutensis Ficure 16.—Distribution of the subspecies of Gerbillus aureus. specimens. In the present study specimens are available from more localities and the systematic position of these gerbils can be more accurately determined. It is now known that these subspecies actually represent populations of a new species (Gerbillus aureus) which can be distinguished readily from G. pyramidum by its smaller size, conspic- uously less tufted tail, and darker dorsal color. The name aureus, because of page priority, is elevated to specifi¢ rank and favillus becomes a subspecies of the new species thus formed. In addition, a new subspecies, Gerbillus aureus nalutensis, is being described from northwestern Tripolitania. The validity of this species (G. aureus) is further strengthened by the absence of any intergradation with G. pyramidum. Setzer (1956) also recognized no intergrades between aureus and favillus and gerbils representing G. pyramidum tarabuli, whose range is to the south. This new species is the only species of gerbil known to inhabit northwestern Tripolitania. The nearest populations of Gerbillus gerbi- lus and G. pyramidum occur much farther south in the northern confines of the Hamada el Hamra. To the east, in the vicinity of Sirte, G. aureus favillus occurs sympatrically with G. pyramidum and G. eatoni. RODENTS OF LIBYA 87 In color and overall body size, members of G. aureus from Liby: closely resemble representatives of Gerbillus pyramidum _ hirtipes Lataste from Ain Sefra, southwestern Algeria, but differ from the latter in having noticeably longer tails. Cranially, the two groups are of comparable size, but can be distinguished by the more massive, compact skulls, cages zygomata, and wider rostra of the Algerian specimens. Ellerman and Morrison-Scott (1951), in keeping with their objective of simplifying nomenclature, relegated Lataste’s Gerbillus hirtipes (1882) to subspecific status under the more widely distributed Gerbillus pyramidum. At this time Tripolitania and the coastal areas of western Libya were not represented by specimens, and Gerbillus aureus was unknown. In the majority of external and cranial characters these specimens from Algeria are much closer to G. aureus than to G. pyramidum; in fact, they bear little resemblance to the latter. When more localities in Algeria are represented by specimens of G@. aureus and G. pyramidum and when topotypes of G@. p. hartipes are available for comparison, the latter will probably be reinstated as a full species, distinct from either G. aureus or G. pyramidum but more closely re- lated to the former, or aureus and hirtipes may be regarded as con- specific, in which case the older hirtipes will take precedence. EcoLoGICAL OBSERVATIONS. Vegetated dunes are apparently the preferred habitat of this gerbil, but they occur also in the littoral deserts where dunes are usually lacking. In the Gebel Nefusa, the habitat consists of rolling uplands with rather dense vegetative cover, and sand, if present, is usually localized. Gerbillus aureus aureus Setzer Gerbillus pyramidum aureus Setzer, Proc. Biol. Soc. Wash., vol. 69, pp. 179-180, Dee. 31, 1956 (12 km W Zliten, Tripolitania Province, Libya). SPECIMENS EXAMINED. Forty, from Tripotrranta: 12 km W Zliten, 12; 25 km N Gharian, 8; 20 km E Rumia, 8 (1 skin only); 3 km E Rumia, 10; 12 km S Chicela, 2. MEASUREMENTS. Averages and extremes of six adult males and measurements of two adult females, 302073 and 302075, from the type locality, are: Total length 236.8 (223-244), 222, 230; length a tail 131.8 (127-137), 125, 129; length of hind foot 30.7 (380-31), 3 30; length of ear 15.2 (13-18), 13, 13; occipitonasal length of a 30.7 (29.9-31.6), 29.2, 30; length of auditory bulla 11.1 (10.9-11.2), 10.7, 10.9; crown length of upper molariform toothrow 4.1 (4—4.3), 4.1, 4.1; greatest breadth across zygomatic arches 16 (15.6-16.5), 15.6, 15.9; least interorbital breadth 5.7 (5.5-6), 5.4, 5.4; breadth of ros- trum at level of antorbital foramina 3 (2.9-3.1), 2.8, 2.9; greatest length of nasals 11.7 (11.4-11.9), 11, 11.5. 8S U.S. NATIONAL MUSEUM BULLETIN 275 Draenosis. Members of this subspecies show pronounced variation in dorsal color, which ranges from uniform, briliant Ochraceous-Buff in some specimens to more subdued Tawny-Olive in others. This darker color results from a strong admixture of dark-tipped hairs. These darker specimens are characterized as follows: Mystacial, rostral, and circumoral areas and supraorbital patch Light Buff; post- auricular region Clay Color heavily suffused with black; eye ring black; pinna of ear dark distally (Hair Brown) with fringe of buff- colored hairs on anterior margin; anteromedial surface of pinna Cin- namon-Buff; vibrissae short, with occasional dark hairs; lateral surface of forearm with buffy patch; fore and hind feet and legs densely haired dorsally and ventrally and each bearing five digits with claws; tail relatively long and indistinctly bicolored Cinnamon-Buff dorsally and Light Ochraceous-Buff ventrally, becoming more sub- dued distally and appearing Light Ochraceous-Buff; terminal pencil relatively reduced and Hair Brown; entire underparts white. The lighter, more brilliantly colored specimens have white rostral, mysta- cial, and circumoral areas, much lighter vibrissae, more distinct postauricular patches, a smaller supraorbital patch, more conspicu- ously bicolored tails, and lack the buffy patch on the forearm. Skull: Medium in size, somewhat gracile and narrow in dorsal aspect; upper molariform toothrow relatively short and individual teeth small; anterior palatine foramina large; auditory bullae small and ventrally inflated; zygomatic arches almost parallel to orbital surface. Comparisons. From the type series of Gerbillus aureus favillus, Gerbillus aureus aureus differs in larger size and larger cranial measure- ments, being comparable in crown length of upper molariform tooth- row, least interorbital breadth and breadth of rostrum at level of antorbital foramina. In color, G. a. aureus is darker and more varied in dorsal color and has a markedly more distinct and darker penicillate tail. Members of the nominate subspecies have more parallel tooth- rows, more ventrally inflated auditory bullae, relatively longer poste- rior palatine canals, and the zygomatic arches are parallel rather than bowed medially. Setzer (1956) used most of the foregoing characters to separate these two subspecies but stated that the skulls of animals of these two subspecies were of comparable size. The present study, however, shows that representatives of G. a. aureus are significantly larger in almost all cranial measurements. For comparison with Gerbillus aureus nalutensis, see account of that subspecies. Remarks. This subspecies apparently represents a genetically heterogeneous group, and the component populations represent a rather broad assemblage of morphological patterns. Specimens from the vicinity of Rumia are slightly darker than those from the type RODENTS OF LIBYA 89 locality and have lighter colored, less prominent tufts on the tail. The common “golden” color phase is also apparently not present in these gerbils from Rumia.“In contrast, the series from 25 kilometers north of Gharian consists almost exclusively of gerbils having this “golden” color. Animals from near Gharian also are wider across the zygomatic arches and have larger molariform teeth. In the aggregate, however, many morphological characters are common to all these different populations and serve to unite them into a single subspecies. Setzer (1957) assigned a single specimen (no. 302102) from 5 kilometers west of El Agheila, Cyrenaica Province, to Gerbillus pyramidum aureus (=Gerbillus aureus aureus). This specimen resem- bles Gerbillus aureus in color and general size but in the prominent tufted tail and all other cranial and external characters, it is typical of Gerbillus pyramidum to which it is here referred. EcoLoGIcAL OBSERVATIONS. The specimens from near Rumia and Chicla were taken near the brink of the coastal escarpment. The habitat here consists of gently rolling valleys and depressions with rather dense vegetative cover consisting of a wide assemblage of close-growing perennial and annual species. The ground in this area is quite rocky, and the soil has a clay or sandy base. Shallow deposits of smooth sand and small dunes are present, but these are of rare occurrence. The collecting site north of Gharian is located on the coastal plain where large, permanently vegetated dunes are present. I have not visited the type locality near Zliten, but presumably the habitat resembles that near Gharian. Gerbillus aureus favillus Setzer Gerbillus pyramidum favillus Setzer, Proc. Biol. Soe. Wash., vol. 69, pp. 179-180, Dec. 31, 1956 (2 km E Sirte, Tripolitania Province, Libya). SPECIMENS EXAMINED. Twenty, from Trrpouitania: 5 km E Sirte, 8;2 km E Sirte, 12. MEASUREMENTS. Averages and extremes of 7 males and 13 females from the above localities are, respectively: Total length 226.1 (216- 240), 220.1 (210-236); length of tail 125.7 (119-135); 119.3 (110-133); length of hind foot 30.4 (30-31), 30.8 (80-31); length of ear 14.4 (13-15), 13.6 (13-15); occipitonasal length of skull 29.7 (29.3-30.5), 29.4 (28.4-30.1); length of auditory bulla 10.5 (10.3-10.8), 10.5 (10.3-10.9) ; crown length of upper molariform toothrow 4.1 (4.1-4.2), 4.2 (44.3); greatest breadth across zygomatic arches 15.5 (15.1—-16.6), 15.7 (15.2-16.3); least interorbital breadth 5.8 (5.5-6), 6 (5.7-6.2); breadth of rostrum at level of antorbital foramina 3.2 (3-3.3), 3.2 (3.1-3.4); greatest length of nasals 11.4 (11-12), 11.3 (10.4-13.1). DiaGnosis. Upperparts uniformly Clay Color becoming paler on sides and with admixture of brownish hairs on back; postauricular 285-134 O—68——7 90 U.S. NATIONAL MUSEUM BULLETIN 275 patches conspicuous and white; supraorbital patch white; mystacial, circumoral and pectoral areas, forelegs, hindlegs, feet, and entire underparts pure white; pinna of ear sparsely haired, darker colored distally, Cinnamon-Buff on anteromedial surface, and bearing a row of fine buffy hairs on anterior margin; vibrissae short and composed almost entirely of white hairs; fore and hind feet bearing five digits with claws; tail relatively short, distinctly bicolored Cinnamon-Buff dorsally, Pale Pinkish Buff ventrally, and with faint terminal Avella- neous pencil. Skull: Relatively small, gracile, and flattened in profile; anterior palatine foramina relatively wide; upper molariform tooth- rows bowed slightly laterally, relatively short, and individual teeth small; auditory bullae relatively small; zygomatic arches bowed slightly medially. For comparisons with G. a. aureus and G. a. nalutensis, see accounts of those subspecies. Remarks. This subspecies is known only from the coastal plain in the vicinity of Sirte on the western shores of the Gulf of Sirte, but its range probably includes a much greater area to the east. I was unable to obtain additional specimens of this subspecies and, conse- quently, obtained no firsthand data regarding their habitat preferences. Setzer (1956, p. 181) describes the habitat at the type locality as consisting of “loose coastal dunes where the vegetation had been heavily eaten by domestic animals.’’ The pale dorsal color of these gerbils may result from a genetic response to the color of these sandy areas. One specimen, no. 302096, from 5 kilometers east of Sirte has large molariform teeth and anterior palatine foramina, a flattened brain- case, and is pallid in dorsal color. These characters are typical of G. a. favillus, and this specimen is referred to that subspecies. This same specimen, however, in size of body, external measurements, and the small size of the skull closely resembles animals belonging to Gerbillus gerbillus. This parallelism probably does not indicate a direct relationship with G@. gerbillus but more likely is the result of a response to similar environmental conditions or represents an extreme in the range of variation for the subspecies G. a. favillus. Gerbillus aureus nalutensis, new subspecies Hoxrorypr. Adult male, skin and skull, USNM 321816, from 40 km ENE Nalut, Tripolitania Province, Libya; obtained Nov. 12, 1961, by H. W. Setzer, original no. 3113. SPECIMENS EXAMINED. Forty, all from the type locality. DiaGnosis. Upperparts Tawny-Olive with strong suffusion of blackish hairs in interauricular and subauricular regions and on rump; sides and flanks paler than dorsum; eye ring black; postauricular and RODENTS OF LIBYA QO] supraorbital patches white; mystacial, rostral, circumoral, and pectoral areas white, the latter tinged with buff; vibrissae short and with numerous dark hairs; pinna of ear drab-colored distally, basally approaching color of dorsum and with row of buffy hairs on anterior margin; fore and hind feet densely haired, white, and with five digits bearing claws; entire underparts pure white; tail Cinnamon-Buff with admixture of brownish hairs dorsally, grading to Pinkish Buff ventrally and terminating in a distinct blackish-brown pencil. Skull: Relatively large and robust, auditory bullae large and bulbous; molariform toothrows long, individual teeth large; rostrum wide; braincase wide and flat. MEASUREMENTS. Averages and extremes of 17 adult males and 13 adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 231.2 (218-249), 224 (213-238), [234]; length of tail 130.4 (117-142), 125.6 (106-132), [130]; length of hind foot 29.2 (27-31), 28.8 (27-31), [30]; length of ear 14.9 (14-16), 14.3 (13-15), [15]; occipitonasal length of skull 30.3 (29.1-31.5), 29.5 (28.7-30.3), [30.7]; length of auditory bulla 11.1 (10.5-11.5), 10.9 (10.2—11.4), [11.3]; crown length of upper molariform toothrow 4.3 (3.9-4.5), 4.3 (3.9-4.4), [4.5]; greatest breadth across zygomatic arches 16.2 (15.7-17.1), 15.6 (15.1-16.1), [16.3]; least interorbital breadth 5.9 (5.3-6.3), 5.8 (5.5-6.1), [6]; breadth of rostrum at level of antorbital foramina 3.3 (2.9-3.4), 3.1 (8-3.4), [3.4]; greatest length of nasals 11.6 (11.1-12.2), 11.3 (10.6—-11.6), [11.8]. Comparisons. From topotypes of Gerbillus aureus aureus, the type and paratypes of G. a. nalutensis differ in having more robust skulls, markedly larger and wider auditory bullae, markedly longer molariform toothrows, larger individual molariform teeth, wider braincases, and wider and shorter rostra. In color, G@. a. nalutensis is somewhat darker dorsally with more suffusion of black hairs on the rump, and the tail has a darker colored pencil. This new subspecies can be distinguished from Gerbillus aureus favillus by darker dorsal color, darker (almost black) pencil, markedly longer molariform toothrows, larger size of individual teeth, much larger, more bulbous auditory bullae, more domed braincase, wider rostrum, and markedly larger size of body and cranium. Remarks. Although a fundamental morphological pattern is always present in members of this subspecies, they vary considerably in color and cranial characters. As in the other two subspecies of G. aureus, dorsal color ranges from the typical dark form, with a heavy suffusion of black, to the more uniformly colored “golden” form. Specimens showing all gradations in intermediate color are also known. Cranially, this subspecies is remarkably polymorphic, partic- 92 U.S. NATIONAL MUSEUM BULLETIN 275 ularly as concerns the size and shape of the auditory bullae, the relative length and width of the anterior palatine foramina, the degree of arching of the braincase, the length of the molariform toothrow, and the size of the individual molariform teeth. This poly- morphism suggests the presence of sibling species within this popula- tion from Nalut, but overlap of characters occurs too frequently, and no specific combinations of characters are demonstrable for individual specimens. Apparently this population from Nalut repre- sents one of pronounced genetic fluidity which has engendered this wide array of morphological patterns. Although this new subspecies is known from only the type locality, its range doubtless includes the coastal plain and littoral deserts of southern Tunisia and, in Libya, probably extends much farther along the coastal plain to the east. In Libya, there are no apparent barriers to dispersal along the coastal plain, and intergradation between animals of G. a. nalutensis and those of the nominate sub- species takes’ place probably somewhere between Tripoli and Nalut. EcoLoGIcAL OBSERVATIONS. The type locality consists of a series of vegetated dunes. These dunes are not extensive and occur sporadi- cally as irregular bands along the coastal plain near the coastal escarpment. The role of the coastal escarpment in retarding the velocity of the winds probably has resulted in the formation of these coastal dunes. Forty-seven gerbils and five jirds were obtained from a single night of trapping at 40 kilometers east-northeast of Nalut. The presence of numerous active burrows plus this large catch suggests a high population density of rodents. A severe wind storm or “ghibli” 10.2 10.4 10.6 10.8 11.0 11.2 11.4 11.6 Ficure 17.—Statistical comparison of length of auditory bulla of the subspecies of Gerbillus aureus: A, G. a. aureus; B, G. a. favillus; C, G. a. nalutensts. RODENTS OF LIBYA 93 2.8 29 3.0 3.1 3.2 3.3 3.4 Ficure 18.—Statistical comparison of breadth of rostrum of the subspecies of Gerbillus aureus. Notation remains the same as in figure 17. developed during the night but had little apparent effect on trapping success. The name nalutensis is used in reference to the village of Nalut on the westernmost limits of the Gebel Nefusa and located a short distance from the type locality. Gerbillus eatoni Thomas Gerbillus eatont Thomas, Proe. Zool. Soc. London, vol. 2, pt. 1, p. 6, October 1902 (El Cusher, Tripolitania Provinee, Libya). GENERAL DISTRIBUTION OF SPECIES. Libya; range probably also includes coastal areas of northern Algeria, Tunisia, and Egypt. DistRIBUTION IN Lispya. Coastal areas of Tripolitania and Cyrenaica. DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Gerbillus eatoni eatoni. CyRENAICA: Coastal plain and littoral deserts in vicinity of Agedabia and north to Gheminez; Tripouitania: Coastal plain of the Gulf of Sirte, probably including the coastal areas to the west. Gerbillus eatoni inflatus. Cyrpnaica: Coastal plain and littoral deserts north and east of the Cyrenaican Plateau. Gerbillus eatoni versicolor. CyRENAICA: Coastal plain of Cyrenaica in vicinity of Benghazi. PUBLISHED RECORDS IN Lipya. Cyrenatca: Vicinity of Benghazi (Klaptoez, 1909); Trrpotiranta: Wadi Agarib, Wadi Aggar, El 94 U.S. NATIONAL MUSEUM BULLETIN 275 Lo Bayen a KILOMETERS Gerbillus eatoni |. eatoni 2. inflatus 3. versicolor Ficure 19.— Distribution of the subspecies of Gerbillus eatont. Cusher (Thomas, 1902); vicinity of Gharian and Tripoli (Klaptocz, 1909). Comparisons. This species most nearly resembles Gerbillus gerbillus but can be distinguished by its darker color, less tufted tail, markedly larger and more inflated auditory bullae, conspicuously domed braincase, larger anterior palatine foramina, and shorter and wider posterior palatine canals. From Gerbillus aureus and Gerbillus pyramidum, G. eatoni differs in its markedly smaller overall size, relatively larger and more inflated auditory bullae, smaller molariform teeth, and more domed braincase. Remarks. Thomas (1902) described Gerbillus eatoni as a full species on the basis of its conspicuously domed and bulbous brain- case and rather large auditory bullae. He further stated that this gerbil was related to Gerbillus andersoni (= Gerbillus gerbillus ander- soni de Winton), but the two species were separable by the larger and more bulbous braincase of G. eatoni. Later, Ellerman and Morrison-Scott (1951) placed G. eatoni in synonymy under Gerbillus gerbillus gerbillus. This erroneous assignment probably was based on too few specimens, although they listed specimens of this gerbil from RODENTS OF LIBYA 95 three localities in northern Tripolitania. Setzer (1957) recognized G. eatoni as a full species largely on the characters established by Thomas. He collected both species from 5 kilometers west of El Agheila, and in the present study, G. gerbillus and G. eatont were found to occur together at several localities in coastal Tripolitania and Cyrenaica without any evidence of interbreeding. The present study indicates that G. eatoni is a full species and can be distinguished from other species of Gerbillus by the same diagnostic characters as set forth by Thomas and by Setzer. Although this species is not abundant in Libya, and large series are lacking, local differentiation has occurred sufficiently to warrant the recognition of three distinct subspecies, each restricted to a particular portion of the Libyan coastal plain. In Libya, the range of this species probably includes all of the coastal regions and in many areas, the transitory desert associated with the coastal escarpment. It is unknown from the Saharan interior where G. gerbillus is the dominant species. EcoLoGIcAL OBSERVATIONS. These gerbils are usually found in areas of loose sand on the coastal plain but frequently occur in habi- tats lacking sand. In many areas the coastal plain is reduced to a narrow fringe of desolate beach or is entirely eliminated. Thus, these coastal populations of gerbils sometimes occur in a variety of eco- logical conditions. Throughout their range in Libya these gerbils occur with several species of jirds (Meriones) and jerboas (Jaculus), fat-tailed sand rats (Pachyuromys), and gerbils of the subgenus Dipodillus. Gerbillus eatoni eatoni Thomas Gerbillus eatont Thomas, Proc. Zool. Soc. London, vol. 2, pt. 1, p. 6, October 1902 (El Cusher, Tripolitania Province, Libya). SPECIMENS EXAMINED. Twenty-five, from Cyrmnaica: 4 km W Gheminez, 6; 10 km S Agedabia, 8; 5 km W El Agheila, 4 (2 skin only); from Tripouirania: 5 km W Sirte, 4; El Cusher, 1 (subadult BM); 15 km WNW Marble Arch, 2. MEASUREMENTS. Averages and extremes of three males and four females from 10 kilometers south of Agedabia, Cyrenaica Province, are, respectively: Total length 214 (208-218), 214.8 (210-222); length of tail 124.3 (117-131), 124.5 (122-126); length of hind foot 27.7 (27-28), 27.3 (26-29); length of ear 14.3 (13-15), 14.5 (13-15); occipitonasal length of skull 28.5 (28.1-28.9), 28.4 (28.1-28.7) ; length of auditory bulla 10.6 (10.5-10.7), 10.5 (10.3-10.6); crown length of upper molariform toothrow 4 (4-4.1), 4 (3.9-4.2); greatest breadth across zygomatic arches 15.2 (15-15.3), 15.4 (15.1-15.6) ; least inter- orbital breadth 5.7 (5.6-5.7), 5.6 (5.4-5.7); breadth of rostrum at 96 U.S. NATIONAL MUSEUM BULLETIN 275 level of antorbital foramina 2.9 (2.8-3), 3 (2.9-3.2); greatest length of nasals 10.6 (10.6-10.7), 10.7 (10.5-10.8). Draenosts. Upper parts Sayal Brown suffused with Bister; tail Cinnamon-Buff and bicolored owing to strong suffusion of brownish hairs dorsally; postauricular patches prominent and white; pinna of ear sparsely haired, Clay Color basally and becoming darker distally ; vibrissae short and formed from about equal numbers of brown and white hairs; eye ring dark brown; mystacial, rostral and pectoral areas, flanks and sides Cinnamon-Buff; forelegs, hindlegs, and feet white dorsally, sparsely haired ventrally and each bearing five digits with claws; entire underparts white. Skull: Relatively small and gracile; upper molariform teeth relatively short; anterior palatine foramina short and wide; posterior palatine canals relatively short; auditory bullae large and markedly inflated; braincase prominently arched. Comparisons. Members of the nominate subspecies can be dis- tinguished from those representing other subspecies in Libya by their smaller size and the marked doming of the braincase. For more detailed comparisons with Gerbillus eatoni inflatus and Gerbillus eatonr versicolor, see accounts of those subspecies. Remarks. Only a single, subadult topotype of G. e. eatoni is available for this study. When specimens of comparable age from various locali- ties along the Gulf of Sirte are compared to this topotype, they differ in having lighter dorsal color, less doming of the skull, and relatively smaller and less inflated auditory bullae. Even though specimens from near Agedabia, Cyrenaica, do not conform precisely to the topotype of G. e. eatoni, they constitute a series of sufficient size for comparisons with other subspecies of G. eatoni in Libya and in the following accounts will be used to represent the diagnostic characters of typical G. e. eatont. Specimens from near Gheminez represent the northeasternmost occurrence of gerbils expressing characters typical of G. e. eatoni and, in the majority of characters, are referable to the nominate subspecies, but in dorsal color and length of tail, they show intergradation with G. e. versicolor to the north. One old and aberrant male specimen, no. 325311, from Agedabia, shows characters of both G. e. eatoni and G. e. versicolor. In its marked divergence of the upper molariform toothrows, less domed braincase, and particolored dorsal pelage, it is nearer to Gerbillus eatoni versicolor. This specimen is here referred to the nominate subspecies because it resembles the latter in size and degree of inflation of the auditory bullae and in the majority of other cranial characters. EcoLoGiIcaL OBSERVATIONS. The habitat at Agedabia is character- ized by extensive sandy plains with occasional small dunes. Vegetative cover is relatively dense and composed of bushy succulent shrubs and RODENTS OF LIBYA 97 other more ephemeral plants. The specimens from near Sirte were collected from the abundant vegetation of the coastal plain. At this locality, the soil is composed of firmly packed clay and sand, and dunes are lacking. Throughout much of its range in northern Tripolitania, this subspecies occurs with members of Gerbillus aureus and Gerbillus gerbillus. Gerbillus eatoni inflatus, new subspecies Ho.otype. Adult male, skin and skull, USNM 325527, from 10 km SW Fort Capuzzo, Cyrenaica Province, Libya; obtained June 1, 1962, by G. L. Ranck, original no. 2203. SPECIMENS EXAMINED. Seven, all from the type locality. MEASUREMENTS. Averages and extremes of five adult males and the measurements of an adult female, 325528, from the type locality, with the measurements of the type in brackets, are, respectively: Total length 226 (218-236), 219, [225]; length of tail 125 (121-131), 120, [123]; length of hind foot 27.2 (26-28), 27, [26]; length of ear 15.4 (15-16), 16, [15]; occipitonasal length of skull 30.6 (29.9-31.7), 30.2, [30.5]; length of auditory bulla 11.1 (10.7-11.6), 11.2, [11.2]; crown length of upper molariform toothrow 3.9 (3.7-4), 3.9, [3.7]; greatest breadth across zygomatic arches 16.1 (15.6-16.4), 16.2, [16]; least interorbital breadth 5.9 (5.5-6.5), 6.1, [5.6]; breadth of rostrum at level of antorbital foramina 3 (2.8-3.1), 2.9, [3.1]; greatest length of nasals 11.7 (11.4—12.3), 12, [11.5]. Draenosts. Middorsal region uniformly colored Sayal Brown grad- ing to Clay Color on sides (one specimen, 325559, represents a very old male and is noticeably lighter and more brilliant in dorsal color with decidedly yellowish hues rather than brownish tones); subauricular region suffused with blackish hairs; postauricular patch distinct and white; rostral, mystacial, supraorbital, and pectoral areas, dorsal surfaces of forelegs, hindlegs, feet, and entire underparts white; some specimens with a faint buffy patch on lateral surface of forearm; pinna of ear Antimony Yellow basally and becoming darker distally; anteromedial surface of pinna covered with ochraceous hairs which extend laterally to anterior margin of pinna as a distinct tuft; eye ring black; vibrissae short and formed from equal numbers of light and dark hairs; fore and hind feet sparsely haired ventrally and with five digits bearing claws; ground color of tail uniformly Cinnamon with slight admixture of brownish hairs dorsally and buffy hairs ventrally; pencil indistinct and Avellaneous. Skull: Relatively large and massive; auditory bullae conspicuously large and inflated; braincase moderately vaulted; upper molariform teeth relatively small and toothrow bowing slightly laterally; anterior palatine foramina large and expanded laterally; posterior palatine canals wide and distinct; pterygoid fossae shallow. 98 U.S. NATIONAL MUSEUM BULLETIN 275 Comparisons. Only a subadult, topotypical specimen of Gerbillus eatoni eatoni is available for study, and because no specimens of Gerbillus eatoni inflatus of comparable age are available, valid com- parison is not possible. Specimens of G. e. inflatus, however, can be readily distinguished from those representing the nominate subspecies from 15 kilometers west-northwest of Marble Arch, Tripolitania Province, and from 10 kilometers south of Agedabia, Cyrenaica Province, by their darker, more uniform dorsal color, generally larger overall size, and conspicuously larger and more inflated auditory bullae. Members of this subspecies also differ from those representing G. e. eatona in having much wider and less domed braincases, wider and longer posterior palatine canals, relatively shorter upper molari- form toothrows, more open pterygoid fossae, and relatively shorter tails. For comparison with Gerbillus eatoni versicolor, see account of that subspecies. Remarks. Representatives of this subspecies can be separated easily from all other subspecies of G. eatona by their markedly larger and more inflated auditory bullae and larger size of body and cranium. The type series was taken from a sandy depression in the hamada near the brink of the coastal escarpment. In these localized depressions, the substrate is composed of poorly sorted sand and gravel and supports a rather uniform plant cover of juniper-like species, large grasses, and smaller, woody shrubs. Burrows are usually widespread throughout these areas and suggest relatively high population densi- ties. Jerboas also occur in this habitat. Although this subspecies is known only from the type locality, its range probably includes the coastal plain and littoral deserts of northern Cyrenaica and those of northern Egypt as far east as the Nile River Delta. The name ¢nflatus refers to the pronounced inflation of the auditory bullae. Gerbillus eatoni versicolor, new subspecies Ho.oryre. Adult male, skin and skull, USNM 325298, from 2 km N Coefia, Cyrenaica Province, Libya; obtained June 15, 1962, by G. L. Ranck, original no. 2341. SPECIMENS EXAMINED. Twenty-five, from Cyrmenaica: 2 km N Coefia, 16 (2 skin only); 8 km N Benghazi, 9 (1 skin only). MEASUREMENTS. Averages and extremes of five adult males and four adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 222.4 (216-236), 221 (205-236), [236]; length of tail 124.2 (119-134), 121.3 (114-130), [134]; length of hind foot 27 (26-28), 27.3 (27-28), [28]; length of ear 16 (15-17), 15.8 (15-16), [15]; occipitonasal length of skull 29.5 (28.7-30.3), 29.2 (28.8-30), [30.3]; length of auditory bulla 10.4 RODENTS OF LIBYA 99 (10-10.8), 10.3 (10-10.6), [10.8]; crown length of upper molariform toothrow 3.9 (3.8-3.9), 3.9 (3.8-4), [3.8]; greatest breadth across zygomatic arches 15.9 (15.4-16.8), 15.8 (15.4-16.5), [16.8]; least interorbital breadth 5.8 (5.5-6.3), 5.8 (5.4-6), [6.3]; breadth of rostrum at level of antorbital foramina 3.2 (3.1-3.4), 3.3 (8-3.4), [8.4]; ereatest length of nasals 11.5 (11.4-11.8), 11.4 (11.3-11.6), [11.8]. Driacnosis. Sides and dorsum variegated or particolored ranging from Pinkish-Cinnamon to Cinnamon; all areas, particularly the sides, with admixture of lighter colored hairs; postauricular patch prominent and Light Buff; mystacial, circumorbital, and pectoral areas Pinkish Buff; eye ring black; underparts generally white, but, in some specimens, with a ventromedian line suffused with Light Pinkish Cinnamon; dorsal surface of forelegs, hindlegs, and feet Pale Pinkish Buff; fore and hind feet sparsely haired ventrally and bearing five digits with claws; pinna of ear relatively long and almost naked, Cinnamon-Buff basally and Deep Grayish Olive distally, and with row of delicate buff-colored hairs on anterior margin; vibrissae relatively short and composed of about equal numbers of white and brown hairs; tail faintly bicolored Cinnamon-Buff dorsally and Pinkish Buff ventrally and bearing an indistinct Drab terminal tuft or pencil. Skull: Relatively large and compact; braincase moderately inflated; interorbital region with distinct longitudinal, median fossa; zygomata relatively heavy; upper molariform toothrow relatively short, straight, yet divergent anteriorly; anterior palatine foramina large and widely open; posterior palatine canals markedly wide and bowed slightly laterad; auditory bullae relatively short and moder- ately inflated; nasals relatively long. Comparisons. This new subspecies differs markedly from specimens representing Gerbillus eatoni eatoni from 15 kilometers west-northwest of Marble Arch, Tripolitania Province, and those from 10 kilometers south of Agedabia, Cyrenaica Province, in darker, more variegated or particolored dorsal pelage (Cinnamon as opposed to Clay Color), more anteriorly divergent and shorter upper molariform toothrows, shorter, narrower, and less inflated auditory bullae, greater length of skull, shorter and wider posterior palatine canals, longer nasals, and less doming of the braincase. From a subadult, topotypical specimen of G. e. eatoni from El Cusher, Tripolitania Province, specimens of comparable age from Coefia are paler in dorsal color, have less distinctly bicolored tails, lack the strong suffusions of brownish hairs on the middorsum, have relatively and absolutely markedly smaller and less inflated auditory bullae, much less inflated braincases, and longer posterior palatine canals. From specimens representing Gerbillus eatoni inflatus from 10 kilo- meters southwest of Fort Capuzzo, Cyrenaica Province, G. e. versicolor 100 U.S. NATIONAL MUSEUM BULLETIN 275 is slightly smaller in overall size, has noticeably shorter and much less ventrally inflated auditory bullae, smaller and more gracile skull, larger upper molariform teeth which form straight toothrows rather than being bowed laterally, narrower and smaller braincase, slightly shorter nasals, paler, more uniform dorsal coloration (Cinnamon as opposed to Sayal Brown), and less prominent subauricular patches. Remarks. Members of this subspecies can be distinguished from other subspecies of G. eatoni in Libya by their particolored dorsal pelage, more parallel upper molariform toothrows, and conspicuously smaller and less inflated auditory bullae. Specimens from 8 kilometers north of Benghazi are similar to G. e. inflatus in more uniform color of dorsum and general body size, but resemble the nominate subspecies in having larger and more domed braincases and more lateral bowing of the upper molariform teeth. In the majority of characters, however, they are closer to G. e. versicolor to which they are here referred. A small series from Gheminez, al- though similar in color to G. e. versicolor, is clearly referable to the nominate subspecies in all morphological characters. The type localities of G. e. versicolor and G. e. inflatus are, geo- eraphically, not too distant, but the Gebel Achdar and the massif of the Cyrenaican Plateau are interposed between them and provide unsuitable habitat for members of this species. Little suitable habitat exists along the coastal plain owing to the encroachment of the coastal escarpment. In the past, gene exchange between these two populations probably has been of rare occurrence, and the two populations have undergone significant morphological divergence. The type series was collected from an area of large, sparsely vege- tated coastal dunes lying between the sea and the coastal plain. It is doubtful if these gerbils are entirely limited to this type of habitat. The gerbils from near Benghazi occupied the rather densely vegetated coastal plain where the substrate was claylike, and sandy areas or dunes were entirely lacking. These gerbils probably are not limited to a particular type of substrate and occur throughout the coastal plain where a wide variety of soil conditions exist. The name “versicolor,” from the Latin meaning variegated or of different colors, refers to the particolored dorsal pelage. Gerbillus gerbillus (Olivier) Dipus gerbillus Olivier, Bull. Sci. Phil. Paris, vol. 2, p. 121, 1801 (Giza Province, Egypt). GENERAL DISTRIBUTION OF sPECIES. Israel, Sinai, Egypt, Sudan, Uganda, and North Africa south through the Sahara including parts of Niger, Mauritania, Chad, and Mali. DistripuTion iN Lipya. Almost ubiquitous throughout the coastal and interior areas of Cyrenaica, Tripolitania, and the Fezzan. RODENTS OF LIBYA 101 DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Gerbillus gerbillus aeruginosus. CyreNAica: Cufra and Bzema oases and the serirs and oases of extreme southeastern Libya. Gerbillus gerbillus discolor. FrzzaAn: Oases, serirs, hamadas, and wadis linking together the various Fezzanese oases. Gerbillus gerbillus gerbillus. Cyrpnatca: Environs of Giarabub Oasis. Gerbillus gerbillus latastei. TrrpotiTanta: Desert areas of central Tripolitania and the Hamada el Hamra. Gerbillus gerbillus psammophilous. CyreNnaica: Coastal deserts near Gulf of Sirte, Oases of Gialo and Tazerbo, eastern margins of the Gebel el Harug el Asued, and the intervening Serir of Calanscio. PUBLISHED RECORDS IN LispyA. CyrEeNAIcA: Augila, El Giof, Es Sahabi, Gialo, Giarabub (de Beaux, 1932); Benghazi (Toschi, 1951); TripouiraANniA: Ain Hammam, Wadi Aggar, ‘‘Attich Loulileh,”’ ‘“TLoumoulieh,” ‘Shup” (Thomas, 1902); Bu Ngem (Toschi, 1951); Frzzan: El Baharia, Gara el Hamra, Hatiet el Fachri, Hatiet er Zeroi, Sebha, Bir el Wasti (de Beaux, 1928); Wadi Tenezoft, Murzuch (Toschi, 1951). Comparisons. Based on measurements of Gerbillus dalloniza Heim de Balsac as given in the original description (Heim de Balsac; 1936, | BY Ly KILOMETERS Gerbillus gerbillus |. aeruginosus 2 discolor 3. gerbillus 4. latastei 5. psammophilous Ficure 20.—Distribution of the subspecies of Gerbillus gerbillus. 102 U.S. NATIONAL MUSEUM BULLETIN 275 p. 45), G. gerbillus can be distinguished by its shorter hind feet, longer rostrum, longer ears, longer molariform toothrow, and markedly larger size of body and cranium. Remarks. Previous workers in Libyan mammals recognized little variation in G. gerbillus, and all of Libya was included within the range of the nominate subspecies. Much larger series are now available from Libya, and this species is now known to be represented by five subspecies and not one as previously supposed. In many areas of Libya, isolated populations of these gerbils occur throughout seemingly barren wastelands. These areas support only a meager vegetative cover, and frequently plant life is entirely wanting. These widely scattered populations are characterized by common morphological characters which indicate at least some degree of genetic relationship. Apparently, seasonal or occasional rains in these desert areas enable plants, primarily grasses, to undergo their brief life cycle and produce abundant quantities of seed which allow small populations of these gerbils to subsist until the next period of mois- ture. By successive seasonal or yearly storms, populations of repro- ductively effective size are able to progressively extend their range. These periods of rainfall may occur within the same year or be spaced over a period of several years. In this manner, small populations of gerbils would be able to ‘bridge’ vast areas in the desert which otherwise would prove insurmountable. These shifting populations illustrate another significant aspect of distribution. Failure of seasonal or periodic rains can cause the ex- termination of “bridging’”’ populations just as their occurrence can perpetuate such populations. Failure of rains thus sets up isolating barriers. Occurrence or lack of rain insures a fluctuating pattern of genetic “input” and “output”? over the range of the species and also makes it probable that the pattern observed now will be altered in subsequent sampling. EcoLoGIcaL OBSERVATIONS. Members of this species are the most ubiquitous of the subgenus Gerbillus in Libya. They are not known to occur in habitats lacking sand and are widely distributed through- out the oases, serirs, and hamadas of the interior. They are commonest along the sandy margins of the oases but occur also in the coastal areas wherever sandy areas are present. They are unknown from the coastal areas of Tripolitania and are not found in Cyrenaica north of the Cyrenaican Plateau. In these areas, they are supplanted by Gerbillus eatoni and members of the Gerbillus pyramidum group. Throughout their range in Libya they are sympatric with many other species of rodents but most frequently occur with Gerbdlus pyramidum and Jaculus jaculus. RODENTS OF LIBYA 103 Gerbillus gerbillus aeruginosus, new subspecies Hototyrr. Adult male, skin and skull, USNM 325146, from El Giof, Cufra Oasis, Cyrenaica Province, Libya; obtained Apr. 3, 1962, by G. L. Ranck, original no. 1920. SPECIMENS EXAMINED. Eighty-four, from Cyrenaica: Bzema Oasis, 8 (1 skin only); El Hauuari, Cufra Oasis, 36 (1 skin only); El Giof, Cufra Oasis, 40 (2 skin only). MeEasuREMENTS. Averages and extremes of 16 adult males and 8 adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 205 (200-215), 205.4 (200-213), [206]; length of tail 117.7 (109-129), 120 (115-128), [119]; length of hind foot 29.4 (28-32), 28.4 (27-31), [29]; length of ear 13.2 (13-14), 12.8 (12-13), [13]; occipitonasal length of skull 28 (27.3-28.8), 27.4 (26.8-27.8), [28.4]; length of auditory bulla 10.3 (9.8-10.8), 10.3 (10.1-10.7), [10.4]; crown length of upper molariform toothrow 3.5 (3.3-3.7), 3.5 (3.4-3.6), [8.5]; greatest breadth across zygomatic arches 15 (14.6-15.5), 14.7 (14.3-15.1), [14.7]; least inter- orbital breadth 5.7 (5.4-6.1), 5.7 (5.4-5.9), [5.9]; breadth of rostrum at level of antorbital foramina 3 (2.7-3.3), 3 (2.9-3.1), [8]; greatest length of nasals 10.3 (9.8-10.6), 10.1 (9.7-10.6), [10.4]. Diaenosis. Interauricular, subauricular, interorbital, and rostral areas same color as dorsum and ranging from Ochraceous-Buff, to Clay Color, to tawny-rust; circumorbital, postauricular spots, mystacial and pectoral areas, fore and hind limbs, and entire under- parts white; vibrissae short and white; fore and hind feet sparsely haired dorsally and ventrally, and each bearing five digits with claws; pinna of ear almost naked and Pale Orange- Yellow with a row of buffy hairs on anterior margin; tail long and distinctly bicolored, ranging from Capucine Buff to Cinnamon dorsally and from Pinkish Buff to Light Buff ventrally and with a distinct pencil, Light Buff ventrally, and varying in dorsal color from Avellaneous in darker colored individuals to Pale Pinkish Cinnamon in paler animals. Skull: Small and gracile; anterior palatine foramina short and elliptical in shape; posterior palatine canals short and bowed slightly laterally ; teeth small; zygomata fragile and convergent anteriorly; braincase slightly inflated and skull rather flattened in profile; auditory bullae moderately inflated ventrally and partially transparent; basioccipitals narrow anteriorly; basisphenoid reduced to a narrow rib between anteromedial edges of auditory bullae; pterygoid fossae large and forming a depression dorsal to pterygoid hamulae; supraorbital bead projecting over dorsal rim of orbit. Comparisons. Compared with topotypical Gerbillus gerbillus gerbillus from Alexandria Road, 5 kilometers northwest of the Pyramids 104 U.S. NATIONAL MUSEUM BULLETIN 275 of Giza, Western Desert Governorate, Egypt, Gerbillus gerbillus aeruginosus differs in smaller size, shorter tail and hind feet, smaller cranial measurements, heavier zygomata, slightly larger and more divergent upper molariform toothrows, more laterally expanded pterygoid fossae, slightly larger lachrymals, and narrower basioc- cipitals. In color, G. g. aeruginosus is darker dorsally, the tail is less distinctly bicolored, and the buffy dorsal color extends farther ventrally and laterally. In general, the range of color in G. g. aeruginosus is much greater than in the nominate subspecies. Compared with topotypes of Gerbillus gerbillus asyutensis Setzer from the beginning of the Wadi el Asyuti, 13 miles southeast of Asyuti, Eastern Desert Governorate, Egypt, G. g. aeruginosus differs in darker, more uniform and less variegated dorsal pelage, larger posterior palatine canals, larger molariform teeth, narrower basioc- cipitals, less ventral inflation of auditory bullae, larger anterior palatine foramina, and larger size of all external and cranial measure- ments. Specimens of Gerbillus gerbillus sudanensis Setzer from the Anglo- Egyptian Sudan can be readily distinguished from G. g. aeruginosus by their paler dorsal color and markedly smaller external and cranial measurements. From measurements of Gerbillus gerbillus agag Thomas from El Fasher, Anglo-Egyptian Sudan, G. g. aeruginosus differs in shorter tail, slightly larger body size, shorter skull, shorter molariform toothrow, shorter nasals, and greater breadth across the zygomatic arches. Only three subadult specimens of G. g. agag are available for study and, in color, these closely approximate G. g. aerugiosus. Gerbillus gerbillus aeruginosus differs markedly from gerbils repre- senting Gerbillus gerbillus andersoni de Winton from the vicinity of Alexandria, Egypt. The latter are noticeably larger in all cranial characters, particularly in the size of the anterior palatine foramina, posterior palatine canals, molariform teeth, and the auditory bullae. The skull is more domed and narrower in G. g. andersoni, and the dorsum and ears are conspicuously darker. For comparisons with Gerbillus gerbillus discolor and Gerbillus ger- billus psammophilous, see accounts of those subspecies. Remarks. In body and cranial size, animals referable to Gerbillus gerbillus aeruginosus are among the smallest of the species of Gerbillus gerbillus in Libya. This trend toward small body and cranial size is apparent in all populations of this species to the east and south. G. g. asyutensis from central Egypt, G. g. sudanensis, and G. g. agag from the Sudan, and gerbils representing G. g. aeruginosus from the Tibesti Area of the Chad, all represent populations of gerbils of small body and cranial size. These common characters may indicate taxo- RODENTS OF LIBYA 105 nomic relationships among these scattered populations, and when the intervening areas are represented by specimens, they will probably contain intergrades. A clinal gradient of progressive increase in size probably will be demonstrable from east to west. In most characters, gerbils from Bzema Oasis are referable to G. g. aeruginosus, but in greatest length of skull and dorsal color, they show intergradation with Gerbillus gerbillus psammophilous to the north. The nearest populations of G. g. psammophilous which could provide the gene pool causing these intermediate characters occur in the vicinity of Bir Bu Zarregh and Bir el Harasc north of the Sand Sea of Rebianna. Apparently, then, this sand sea is not an absolute barrier but a filter for genetic exchange between animals strictly referable to G. g. psammophilous and G. g. aeruginosus. Animals belonging to G@. g. aeruginosus are exceptional in their wide range of dorsal coloration, and three distinct groups are recog- nizable, ranging from Ochraceous-Buff, to Clay Color, to tawny-rust. The majority of individuals are tawny-rust. A genetic response to the local character and color of the sand in Cufra Oasis may account for this wide range of dorsal coloration. One specimen, 319683, from El Giof, Cufra Oasis, differs markedly from all other specimens of G. g. aeruginosus in having a more promi- nently vaulted skull (especially the parietals), smaller and less inflated auditory bullae, and heavier zygomata. In all other morphological characters this specimen clearly represents Gerbillus gerbillus. In the marked inflation of the braincase, however, it resembles Gerbillus eatont whose range includes the Egyptian and Libyan coasts. This similarity to G. eatoni is entirely fortuitous, and this specimen is probably aberrant or represents an extreme in the range of variation for the subspecies. EcoLoGIcAL OBSERVATIONS. These gerbils prefer the sandy areas along the periphery of the oasis but occasionally were taken from areas of open sand within the palm groves. At El Giof, a large series was obtained from a sandy clearing in the interior of the oasis. Usually however, Gerbillus pyramidum and Gerbillus campestris are more abundant in the oasis proper. At Bzema, El Giof, El Hauuari, and most of the other large oases of southern Cyrenaica, large saline lakes occupy the interior of the oasis and form hard precipitates of salt along their margins. These barren areas are surrounded by a ring of sedges and halophytic plants, and G. gerbillus occurs here only sparingly; however, Gerbillus cam- pestris occurs abundantly in these mesic habitats. The name aeruginosus, from the Latin meaning rust or rusty, alludes to the rusty dorsal color of most specimens. 285-134 O—68——8 106 U.S. NATIONAL MUSEUM BULLETIN 275 Gerbillus gerbillus discolor, new subspecies Hoxortyre. Adult male, skin and skull, USNM 322461, from Ghat, Fezzan Province, Libya; obtained Dec. 18, 1961, by G. L. Ranck, original no. 1116. SPECIMENS EXAMINED. One hundred sixty-two, from TRIPOLITANIA: 2 km SW Hun, 18; 5 km S Socna, 6; Bir Fergian, 10 km S Soena, 2; from Frzzan: Edri, 11; Temenhint Oasis, 30 km NE Sebha, 12; 3 km NW Sebha, 5; 5 km NW Sebha, 3 (1 skin only); 10 km SE Sebha, 4 (skin only); El Abiad, 60 km SW Sebha, 18 (2 skin only; 2 skull only); 75 km W Ubari, 11; Meseguin 1; Umm el Araneb, 2; 6 km N Murzuch, 1; 55 km SSW Serdeles, 8; 20 km N Ghat, 1; 12 km N Ghat, 13 (4 skull only) ; Ghat, 25 (1 skeleton) ; El Gatrun, 17; El Barcat, 4. MeAsuREMENTS. Averages and extremes of 12 adult males and 6 adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 211 (200-220), 210.7 (200-218), [213]; length of tail 121.6 (112-130), 124.3 (116-128), [125]; length of hind foot 28.6 (28-30), 28.3 (27-29), [29]; length of ear 13.4 (13-14), 13.2 (12-14), [13]; occipitonasal length of skull 28.3 (27-28.9), 27.9 (27.1-29), [28.4]; length of auditory bulla 10.5 (10.1-10.7), 10.3 (10-10.7), [10.6]; crown length of molariform tooth- row 3.6 (3.5-3.8), 3.6 (3.5-3.6), [3.6]; greatest breadth across zygomatic arches 15.4 (15.2-15.6), 14.6 (14.5-14.8), [15.6]; least interorbital breadth 5.7 (5.2-6), 5.7 (5.5-5.8), [5.5]; breadth of rostrum at level of antorbital foramina 3.1 (2.9-3.3), 3 (2.9-3), [3]; greatest length of nasals 10.6 (10.2-11.1), 10.3 (9.8-10.6), [10.5]. Diagnosis. Upperparts Clay Color, suffused throughout with brownish hairs imparting a streaked or marbled appearance; sub- auricular patch prominent and Cinnamon-Buff; pinna of ear sparsely haired and Clay Color; preauricular patch Pinkish Buff and extending as a row of fine hairs onto anterior margin of pinna; postauricular patch, circumorbital, rostral and mystacial areas, dorsal surfaces of fore and hind feet and entire underparts white (in some specimens, the venter is Pale Pinkish Buff owing to artificial staining); fore and hind feet with five digits, each bearing a claw; tail distinctly bicolored Cinnamon-Buff dosally, Light Buff ventrally and terminating in a prominent pencil, Avellaneous dorsally and Light Buff ventrally; vibrissae short and composed of both brownish and whitish hairs. Skull: Medium in size; braincase moderately arched; auditory bullae relatively large and inflated: anterior palatine foramina and posterior palatine canals narrow; zygomata moderately heavy and convergent anteriorly; posterior lacerated foramina between basioc- cipital and anteromedial margins of auditory bullae reduced to slitlike aperatures. RODENTS OF LIBYA 107 ComPARISONS. From topotypes of Gerbillus gerbillus gerbillus, the type and paratypes of G. g. discolor differ in having narrower anterior palatine foramina and_ posterior palatine canals, slightly more inflated auditory bullae, shallower pterygoid fossae, shorter skulls, shorter nasals, greater zygomatic breadth, and more robust skulls. Gerbils from the Fezzan are smaller in overall length and length of tail and hind foot; in color, they are noticeably darker and appear more streaked owing to a greater admixture of brownish hairs on dorsum. Two specimens, 321821 and 321822, from 40 kilometers north of Sinauen and a single specimen, 321825, from 5 kilometers east of Derg, Tripolitania Province, are referable to Gerbillus gerbillus lataster and differ from those of G. g. discolor in having wider anterior palatine foramina, more gracile zygomata, more vaulted braincases, and larger external and cranial measurements, being of comparable size only in least interorbital breadth and length of nasals. In color, these specimens from Tripolitania are more uniform in dorsal color, with less suffusion of brownish hairs. When the type series of G. g. discolor and Gerbillus gerbillus aeru- ginosus are compared, G. g. discolor differs in having slightly paler, more variegated dorsal color, wider and more inflated auditory bullae, narrower posterior palatine canals, larger cheek teeth, proportion- ately smaller and deeper pterygoid fossae, wider basioccipitals, and markedly larger size of all external and cranial measurements, except length of hind foot and breadth of rostrum at the level of the antorbital foramina. For comparison with Gerbillus gerbillus psammophilous, see account of that subspecies. Remarks. Gerbils from Edri, near the northern limits of the range of G. g. discolor, are similar cranially to topotypes of G. g. discolor from Ghat, Fezzan. They are intermediate in color, however, between that of a single representative, 321825, of Gerbillus gerbillus lataster from Derg, Tripolitania, and topotypes of G. g. discolor. The color of these specimens from Edri suggests a relationship to G. g. lataster whose range is to the north. Unfortunately, specimens are not avail- able from the Hamada el Hamra and the Hamada de Tinrhert which are located north of Edri and between the ranges of G. g. lataster and G. g. discolor. Although sandy habitats are not widespread in these hamadas, localized sandy areas are present and doubtless support small populations of these rodents. These hamadas, there- fore, provide an avenue through which gene exchange takes place between populations of G. g. latastei to the north and those of G. g. discolor to the south. Gerbils inhabiting these regions may be inter- grades between these two subspecies. 108 U.S. NATIONAL MUSEUM BULLETIN 275 Representatives of this subspecies from El Gatrun on the eastern margin of the Idehan Murzuch are paler in dorsal color than those from elsewhere in the Fezzan. When specimens of Gerbillus gerbillus become available from the Serir Tibesti and other regions to the south, they may represent an undescribed subspecies to which the specimens from El Gatrun will be referable. Gerbils from El Abiad, 55 kilometers west of Ubari, 75 kilometers south-southwest of Serdeles, and 12 kilometers north of Ghat are remarkably uniform in color and cranial characters. Apparently the sandy beds of the Wadi el Agial, Wadi Irauen, and the Wadi Tenezoft act as dispersal corridors which insure genetic uniformity among these widely scattered populations. Members of this subspecies from the vicinity of Hun, Socna, and Bir Fergian, Tripolitania Province, show many characters typical of Gerbillus gerbillus psammophilous, whose range includes most of Cyrenaica and the coastal areas of the Gulf of Sirte. In the degree of inflation of the auditory bullae, breadth of the anterior palatine fora- mina, and the size and shape of the posterior lacerated foramina between the basioccipital and auditory bullae, they resemble G. g. psammophil- ous, but in the majority of cranial characters, they are closer to G. g. discolor to which they are here referred. For additional comments regarding gene exchange with G. g. psammophilous, see under “remarks” in account of that subspecies. Although this subspecies is characterized by generally darker, more variegated dorsal color, individuals in the population range from uni- form colors of pale, subdued tones to rather brilliant, ochraceous hues. Partial albinism is also of occasional occurrence. In gerbils from Sebha and Temenhint Oases of the central Fezzan, this broad range in dorsal color is particularly striking. These oases apparently represent areas in which the genetic character of the population is less rigidly fixed. These small gerbils are probably the most widely distributed rodent in the Fezzan. They are most abundant near the periphery of the oases where the palm groves are less dense and open sandy areas are more widespread. In the Fezzan, G@. g. discolor is sympatric with the larger, and usually more abundant, Gerbillus pyramidum tarabult. Other rodents, such as Gerbillus amoenus, Jaculus jaculus, Meriones caudatus, and Acomys cahirinus occur with G@. gerbillus but usually are far less abundant. The range of this subspecies, as far as is known, does not include coastal Libya. In the coastal areas of northern Tripolitania, members of the Gerbillus pyramidum group are the dominant gerbils. The term discolor, from the Latin meaning “‘of different color or colors,” is used for the subspecies name in reference to the variegated character of the dorsal pelage. RODENTS OF LIBYA 109 Gerbillus gerbillus gerbillus (Olivier) Dipus gerbillus Olivier, Bull. Sci. Soc. Philom., Paris, vol. 2, p. 121, 1801 (Giza Province, Egypt). SPECIMENS EXAMINED. Twenty-six, from Cyrenaica: Giarabub, 10 (1 skin only); Bahr el Tubat, 21 km ESE Giarabub, 11; 24 km SSE Giarabub, 5. MEASUREMENTS. Averages and extremes of five males and measure- ments of two females from Giarabub are, respectively: Total length 214 (205-221), 214, 205; length of tail 127 (121-135), 122, 119; length of hind foot 29 (28-30), 31, 32; length of ear 13 (13-13), 12, 13; occip- itonasal length of skull 28.7 (28.1-29.4), 28.1, 27; length of auditory bulla 10.7 (10.2-11.2), 9.9, 10.2; crown length of molariform toothrow 3.7 (3.6-3.8), 3.4, 3.6; greatest breadth across zygomatic arches 15.3 (14.5-15.8), 14.7, 14.9; least interorbital breadth 5.9 (5.7-6), 5.6, 5.5; breadth of rostrum at level of antorbital foramina 3 (3-3.1), 3, 2.8; ereatest length of nasals 10.6 (9.9-11.6), 10.6, 10.4. Draenosis. Upperparts Cinnamon-Buff becoming paler on sides and flanks owing to suffusion of whitish hairs; circumorbital regions, mystacial and pectoral areas, dorsal surfaces of fore and hind feet, and entire underparts white; postauricular patch distinct and white; vibrissae short and composed of brownish and white hairs; pinna of ear almost naked, Warm Buff, and with row of fine, buffy hairs on anterior margin; fore and hind feet sparsely haired ventrally and bearing five digits, each with a claw; tail indistinctly bicolored Light Ochraceous-Buff above and Light Buff below, and with a prominent terminal pencil, Tilleul-Buff dorsally and Pale Pinkish Buff ventrally. Skull: Medium in size and moderately robust; zygomata heavy; lachrymals large; molariform teeth moderately large; auditory bullae markedly large and inflated; braincase moderately domed. Comparisons. From topotypical Gerbillus gerbillus gerbillus from Alexandria Road, 5 miles northwest of the Pyramids of Giza, Cairo Area, Egypt, specimens from Giarabub and vicinity differ in having slightly heavier zygomata, larger lachrymals, larger and more in- flated auditory bullae, slightly larger molariform teeth, slightly narrower basioccipitals and shorter overall size of body. In color, the majority of specimens are closer to Gerbillus gerbillus psammophilous, whose range is farther west and south. In the majority of cranial characters and in external measurements, however, they resemble the nominate subspecies to which they are here referred. For comparisons with Gerbillus gerbillus aeruginosus and G. g. psammophilous, see accounts of those subspecies. Remarks. In cranial characters, these specimens from Giarabub are indistinguishable from those from Bahr el Tubat and Siwa Oasis, western Egypt. These populations also do not differ significantly 110 U.S. NATIONAL MUSEUM BULLETIN 275 from those from the type locality. Apparently, the low-lying areas associated with the Wadi Natroun, Qattara Depression, Siwa Oasis, and Bahr el Tubat provide a continuum of suitable habitat linking these various populations together. In some characters, notably heavy zygomata, large and ventrally inflated auditory bullae, narrow basioccipital and small body size, these gerbils from Giarabub show evidences of gene exchange with G. g. psammophilous to the west. Apparently they are able to overcome the barrier imposed by the Sand Sea of Calanscio in this region of Libya. Some gerbils from Giarabub are noticeably darker, more orangish in dorsal color, than others. This same feature was observed in jerboas (Jaculus jaculus) from Giarabub and is presumably an adaptive response to the different color of the sand in this area. EcoLoGICAL OBSERVATIONS. Giarabub Oasis is a portion of the ereat depression formed from the east-west linkage of the Wadi Natroun, Qattara Depression, and Siwa Oasis. Although located in the interior of the desert, all three “‘sebchets’”’ are below sea level. Sandy areas of large extent have accumulated here and provide desirable habitat for these gerbils. Plant cover is more abundant in these low-lying areas than elsewhere; dense stands of Phragmites are widespread in the bottoms of the depressions; and Tamarix occupies the more elevated areas where the soil is firmer and more stable. Various other species of woody shrubs are also present. Many resemble the chenopods, woody composites, and thorny perennials of the western United States. The series from Giarabub was obtained from some large dunes near the oasis. A concentration of sandy-clay hummocks within a localized sandy elevation of the valley floor formed the habitat at the collecting site 24 kilometers south-southeast of Giarabub. The vegetative cover here was particularly dense and varied. Bahr el Tubat is a large, quite shallow, saline lake surrounded, in some places, by dense stands of reeds and sedges. In other areas of the shoreline, salty deposits of great thickness and extent occur, rendering the habitat unsuitable for mammals. The specimens from Bahr el Tubat were taken from a series of vegetated dunes beyond the lake and slightly higher in elevation. Gerbillus gerbillus latastei Thomas and Trouessart Gerbillus gerbillus latastei Thomas and Trouessart, Bull. Soc. Zool. France, ser. 5, vol. 28, pp. 171-174, July 28, 1903 (Kebili, Southern Tunisia). SPECIMENS EXAMINED. Three, from TRipotiTANIA: 40 km N Sinauen, 2; 5 km E Derg, 1. RODENTS OF LIBYA 111 MEASUREMENTS. The measurements of an adult male, 321822, and female, 321821, from 40 kilometers, north of Sinauen, and of an adult male, 321825, from 5 kilometers east of Derg are, respectively: Total length 219, 215, 217; length of tail 128, 130, 130; length of hind foot 30, 30, 29; length of ear 14, 14, 13; occipitonasal length of skull 29.3, 28, 28.7; length of euditory bulla 10.8, 10.5, 10.5; crown length of upper molariform toothrow 3.8, 3.7, 3.8; greatest breadth across zygomatic arches ?, 14.6, ?; least interorbital breadth 5.7, 5.6, 6.1; breadth of rostrum at level of antorbital foramina 3.3, 2.9, 3.1; ereatest length of nasals 10.6, 10.6, 10.6. Driaenosis. Upperparts lustrous, Clay Color with uniform admixture of brownish hairs extending over sides of body nearly to the venter where it has greater suffusion of whitish hairs; subauricular patches distinct, Cinnamon-Buff and also with admixture of brownish hairs; mystacial, rostral, preauricular, and circumorbital areas, postauricular patch, dorsal surfaces of fore and hind feet, and entire underparts white; pinna of ear almost naked, Ochraceous-Buff, and with row of buffy hairs on anterior margin; vibrissae short and white with oc- casional darker hairs; fore and hind feet sparsely haired, with five digits, each bearing a claw; tail distinctly bicolored Cinnamon-Buff dorsally, white ventrally, with prominent terminal pencil, Avellaneous dorsally and white ventrally. Skull: Relatively large, molariform teeth long; interorbital breadth moderately wide; nasals_ short, auditory bullae and posterior palatine canals large; zygomata markedly fragile and convergent anteriorly; supraorbital bead prominent; braincase moderately vaulted. Comparisons. The two specimens, 321821 and 321822, from near Sinauen and the single specimen, 321825, from Derg differ from topotypes of the nominate subspecies in darker color, more streaked and lustrous dorsal pelage, slightly smaller overall length, slightly longer ears, slightly longer skulls, longer molariform teeth, narrower interorbital breadth, slightly shorter nasals, larger auditory bullae, and longer posterior palatine canals. Compared to a single topotype (MNHN 57) of Gerbillus gerbillus foleyi Heim de Balsac from Beni Abbes, western Algeria, the speci- mens from Libya are similar in dorsal color, but differ in having smaller hind feet and auditory bullae, narrower zygomatic breadths, and slightly shorter nasals. For comparisons with Gerbillus gerbillus discolor and Gerbillus gerbillus psammophilous, see accounts of those subspecies. Remarks. The specimens from near Sinauen are slightly darker in dorsal color than the specimen from Derg and also have larger auditory bullae, shorter posterior palatine canals, and more vaulted 112 U.S. NATIONAL MUSEUM BULLETIN 275 braincases. These differences are too slight to warrant assignment of these specimens to separate subspecies, and they are here referred to the same subspecies. Ellerman and Morrison-Scott (1951) considered G. g. lataster to be a little-known and dubious form. In the present study comparative specimens of G. g. latastei are not available, but Thomas and Trouessart (1903), in the original description, included the following measure- ments: Length of head and body, 97; length of tail, 110; length of hind foot, 27.5; length of ear, 12; length of skull from the tip of the nasals to the extremity of the interparietal, 31; length of nasals, 12.5; interorbital breadth, 6.3; length of diastema, 8.5; length of the upper molariform toothrow, 4.4. In the original description latastet was also characterized as having patches above the eyes and behind the ears, all underparts pure white, hairs grayish at the base, except the post- auricular patches which are entirely white, and the dorsal color of the tail the same color as the back and white below with a small brownish pencil. According to Thomas and Trouessart, it can be distinguished from all other gerbils by its brilliant color. The three specimens from Tripolitania agree closely with the above color description but are somewhat smaller in most cranial characters and larger in most external measurements. Owing to inadequate comparative materials, the assignment of these specimens to G. g. latastei is provisional and based largely on geographic grounds. The specimens from near Sinauen were taken from a broad slope in the hamada where vegetation was sparse and interspersed with small, transient dunes. The habitat at Derg was similar to that at the above locality, but the plant cover was more abundant and confined to mar- gins of a small wadi, and the sand was more sporadic and localized. This subspecies probably has a much larger distribution in Libya than the few specimens would indicate, and the range probably includes a large portion of the Hamada el Hamra, the Hamada de Tinrhert, and the inner margins of the Tripolitanian coastal plain. Gerbillus gerbillus psammophilous, new subspecies Ho.uotypr. Adult male, skin and skull, USNM 325078, from Gialo Oasis, Cyrenaica Province, Libya; obtained Mar. 16, 1962, by G. L. Ranck, original no. 1790. SPECIMENS EXAMINED. One hundred eighty, from CyrEnaica: 10 km S Agedabia, 27 (2 skin only); 65 km WNW EI Agheila, 1; 5 km W EI Agheila, 2; Gasr es Sahabi, 12 (6 skull only); Augila, 23; Gialo Oasis, 58; 150 km S Gialo, 1; Wadi er Rueis, 340 km WNW Tazerbo, 3; El Gezira, Tazerbo Oasis, 16; Tazerbo Oasis, 23; Bir bu Zarregh, 3; Bir el Harasc, 9; from TripouiraniaA: 15 km WNW Marble Arch, 2. RODENTS OF LIBYA Lis MEASUREMENTS. Averages and extremes of 31 adult males and 18 adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 214.4 (202-220), 208.1 (200-220), [210]; length of tail 122.5 (117-129), 120.3 (113-128), [122]; length of hind foot 29.4 (28-31), 28.6 (27-30), [29]; length of ear 13.9 (13-14), 13.3 (13-14), [14]; occipitonasal length of skull 28.6 (27-29.9), 28.1 (27.3-29.5), [28.5]; length of auditory bulla 10.4 (9.8-11), 10.3 (9.7-10.9), [10.5]; crown length of upper molariform toothrow 3.6 (3.4-3.9), 3.6 (3.4-3.9), [3.7]; greatest breadth across zygomatic arches 15.5 (15-16.4), 15.1 (14.7-15.4), [15.7]; least inter- orbital breadth 5.9 (5.4-6.4), 5.7 (5.3-6.2), [5.7]; breadth of rostrum at level of antorbital foramina 3 (2.7-3.2), 3.1 (2.9-3.2), [3]; greatest length of nasals 10.6 (10.4-11.6), 10.5 (10—-11.3), [10.6]. Draanosis. Upperparts uniformly Cinnamon-Buff becoming inter- spersed with white hairs on sides and pectoral areas; circumorbital region, rostral area, postauricular areas, and entire underparts white; fore and hind feet Light Buff dorsally, sparsely haired ventrally, and each bearing five digits with claws; pinna of ear Warm Buff, finely haired and with thin row of buffy hairs along anterior margin; vibrissae short and usually white, but with occasional darker hairs present; tail indistinctly bicolored Light Buff ventrally with narrow dorsal line of Light Ochraceous-Buff terminating in a distinct pencil, Avellaneous dorsally and Light Buff ventrally. Skull: Medium in size; moderately robust; auditory bullae moderately inflated; zygomata heavy; basi- occipital constricted anteriorly and forming distinct foramina near anteromedial margins of auditory bullae; external pterygoid fossae forming distinct depressions dorsal to posteriorly flaring pterygoid hamulae; braincase moderately vaulted. Comparisons. From topotypes of Gerbillus gerbillus discolor from Ghat, Fezzan Province, Gerbillus gerbillus psammophilous differs in having narrower auditory bullae, more anteriorly constricted basi- occipitals, larger foramina between basioccipital and auditory bulla, more arched braincase, less divergent pterygoid hamulae, greater occipitonasal length, greater interorbital breadth, and slightly larger hind feet. In color, G. g. psammophilous is much paler and less streaked dorsally and has a less prominent subauricular patch and a lighter pencil. Gerbillus gerbillus psammophilous differs from topotypical specimens of Gerbillus gerbillus gerbillus in having heavier zygomata, more anteriorly constricted basioccipitals, more distinct foramina between the basioccipitals and the auditory bullae, smaller, more slitlike posterior palatine canals, shorter overall length, slightly larger occipitonasal length, greater breadth across zygomatic arches, longer 114 U.S. NATIONAL MUSEUM BULLETIN 275 nasals, and rostra less decurved distally. These gerbils are similar to those of the nominate subspecies in dorsal color but appear slightly paler owing to a greater suffusion of whitish hairs on sides, more white around the eyes and rostrum, less prominent subauricular patches, and a paler pencil. Gerbils representing the nominate subspecies from the vicinity of Giarabub, Cyrenaica Province, resemble those referable to G. g. psammophilous but have larger, more massive skulls, larger, more inflated auditory bullae, and larger anterior palatine foramina. In color, they are almost indistinguishable from topotypes of G. g. psammophilous. Gerbillus gerbillus psammophilous can be readily distinguished from topotypical specimens of Gerbillus gerbillus andersoni by much paler, more orangish dorsal color, shorter anterior palatine foramina, less vaulted braincase, less ventrally inflated auditory bullae, shorter and smaller molariform toothrow, more prominent supraorbital bead, less robust zygomata, and smaller size of all cranial measurements. From topotypes of Gerbillus gerbillus asyutensis from the Wadi Asyuti, Egypt, G. g. psammophilous differs in having markedly darker, less variegated dorsal pelage, shorter posterior palatine canals, wider basioccipitals, and larger size of all cranial measurements. Compared with two specimens, 321821 and 321822, representing Gerbillus gerbillus latastei from 40 kilometers north of Sinauen, Tripolitania Province, G. g. psammophilous has slightly smaller and more ventrally inflated auditory bullae; smaller molariform teeth; heavier zygomata; shorter occipitonasal length; shorter tail; markedly paler, more subdued dorsal color with less suffusion of brownish hairs; a less distinctly bicolored tail; and vibrissae with fewer dark hairs. Paratypes of G. g. psammophilous can be distinguished from the type and paratypes of Gerbillus gerbillus aeruginosus from El Giof, Cufra Oasis, by their paler dorsal color and markedly larger size of all cranial measurements, being similar in length of auditory bulla, crown length of upper molariform toothrow, and least interorbital breadth. G. g. psammophilous also has narrower posterior palatine canals, heavier zygomata, more ventrally inflated auditory bullae, less domed skull, and less distally decurved rostrum. Remarks. Members of this subspecies show significant intergrada- tion with other subspecies whose major ranges are far removed geographically. Gerbils from Giarabub and Bahr el Tubat, in some characters, suggest intergradation between G. g. psammophilous and the nominate subspecies. In color, gerbils from Tazerbo Oasis, Bir el Harasc, and Bir bu Zarregh show evidences of gene exchange with G. g. aeruginosus to the south. Specimens from near Hun, Socna, and RODENTS OF LIBYA 115 Bir Fergian, Tripolitania Province, are intermediate in color and cranial characters between gerbils from the Fezzan and those from Cyrenaica. The Sand Sea of Calanscio to the east and the Sand Sea of Rebianna to the south apparently do not act as absolute barriers to the move- ments of these gerbils. Likewise, the volcanic ramparts of the Gebel el Harug el Asued of eastern Tripolitania and western Cyrenaica do not entirely limit the east-west dispersal of this species in Libya. Three specimens from the Wadi er Rueis, 340 kilometers west-northwest of Tazerbo are indistinguishable from those from the type locality in color and cranial characters. A pathway for gene exchange. between populations of gerbils from the Fezzan and Cyrenaica is provided by the numerous small oases that circumscribe the Gebel el Harug el Asued. When specimens become available from these areas, they probably will show characters allying them to populations of gerbils in both the Fezzan and Cyrenaica. Cranially, gerbils from the coastal areas near Agedabia, Marble Arch, and El Agheila are indistinguishable from those from the type locality in the Saharan interior. In color, however, these animals from the coast are much paler dorsally with greater suffusion of whitish hairs. This trend toward darker dorsal color increases pro- gressively toward the south and reaches its extreme in gerbils from Tazerbo and Cufra Oases. A single specimen, 325105, from 150 kilo- meters south of Gialo is intermediate in dorsal color between gerbils from Tazerbo and Gialo Oases. Similarly, specimens from Gasr es Sahabi, which is located midway between Gialo Oasis and the coast are lighter than those from Gialo but darker than those from the coastal deserts. Thus a north-south, clinal gradient in dorsal color is demonstrable within populations of gerbils from Cyrenaica. This gradient in dorsal color reaches its greatest intensity in gerbils in- habiting the southern oases. EcoLoGIcAL OBSERVATIONS. These gerbils range throughout the sandy environs of the oases, where they are frequently associated with debris near the bases of palm trees. They also occur in sandy margins of wadis and frequently inhabit the margins of the sand seas or ‘‘Ramleh” where unstable, mountainous dunes are wide- spread. The larger sand seas, however, such as Rebianna and Calanscio, contain vast areas of constantly shifting dunes which probably are not inhabited by these mice. Apparently sand seas of small extent are not barriers to dispersal. The widely scattered distribution of this subspecies and the collecting sites at 150 kilometers south of Gialo and from the Wadi er Rueis confirm this. In the coastal areas of Cyrenaica this species is supplanted by Gerbillus eatoni, which prefers the more densely vegetated margins of the coastal plain. 116 U.S. NATIONAL MUSEUM BULLETIN 275 The subspecies name psammophilous, from the Greek meaning “Sand lover,’ suggests a predilection of members of this subspecies for habitats of a sandy character. Gerbillus pyramidum E. Geoffroy Gerbillus pyramidum E. Geoffroy, Catalogue des mammiféres du Museum Na- tional d’Histoire Naturelle, p. 202, 1803 (near Pyramids of Giza, Giza Province, Egypt). GENERAL DISTRIBUTION OF SPECIES. Israel, Sinai, Egypt, Libya, Algeria, Tunisia, and Morocco; southward throughout the Sahara to central Sudan, Chad (Tibesti Mountain Area), Niger, and Mauritania. DIsTRIBUTION IN Lisya. Desert and coastal regions of Tripolitania and throughout the Fezzan. (Only a single specimen is known from Cyrenaica.) DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Gerbillus pyramidum hamadensis. TRIPOLITANIA: Coastal areas and interior deserts of Tripolitania north of the Gebel es Soda and Hamada de Tinrhert. Gerbillus pyramidum tarabuli. Fnzzan. penesy a KILOMETERS Gerbillus pyramidum |. hamadensis 2. tarabuli Ficure 21.—Distribution of the subspecies of Gerbillus pyramidum. RODENTS OF LIBYA 117 PUBLISHED RECORDS IN Lisya. Cyrenaica: Vicinity of Benghazi (Ghigi, 1920). The occurrence of this species this far north in Cy- renaica is questionable. While I have not examined these specimens, it seems likely that they would be representatives of Gerbillus eaton; TrRIPOLITANIA: Wadi Agarib, Wadi Aggar, Ain Hammam, Ferdjan, El Koshby, Linzerat, Wadi Sultan, Tamari-Ferdjan (Thomas, 1902); Gargaresch, Tripoli (Andreucci, 1914); Ghadames (Perugini, 1929) ; Giofra, Tripolitania settentrionale (Zavattari, 1937); Frzzan: God- dua, Sebha, Umm el Abid, Zeigen (Thomas, 1902); Murzuch (Andreucci, 1914); Sciati, Hofra (Zavattari, 1937). Comparisons. From Gerbillus aureus, which it somewhat resembles, this species can be distinguished by its larger skull and body, longer and more tufted tail, generally lighter color, longer and narrower posterior palatine canals, and relatively narrower anterior palatine foramina. This species can be distinguished from Gerbillus eatona by its markedly larger overall size (occipitonasal length usually more than 30 mm), relatively smaller and less inflated auditory bullae, larger molariform teeth, and less domed, almost flattened braincase. This species is markedly larger in all respects than Gerbillus gerbillus and has relatively larger molariform teeth, less inflated auditory bullae, and less orange color in the dorsal pelage. Gerbillus pyramidum closely resembles Gerbillus perpallidus Setzer from Egypt but can be distinguished by its darker color, markedly larger skull, less inflated auditory bullae, more open pterygoid fossae, longer anterior palatine foramina, and much more conspicuous supra- orbital beads. The foregoing characters were used by Setzer (1958 p. 221) to separate these two species and I concur. Remarks. These gerbils are widely distributed throughout North Africa from the Red Sea to the Atlas Mountains and occur virtually throughout the Sahara; however, there is a conspicuous hiatus in their distribution in western Egypt and eastern Libya. In Libya, the oases of Gialo, Giarabub, Tazerbo, and Cufra, and in Egypt, Siwa Oasis and the low-lying areas of the Qattara Depression contain abundant suitable habitat for them, but as yet, no specimens are known from these areas. Apparently, members of this species are unable to circumvent the barriers imposed by the Cyrenaican Plateau and the northern part of the Libyan Desert and have been unable to extend their range into these parts of Libya and Egypt. In Libya, the Serir of Calanscio and the Sand Sea of Calanscio doubtless serve to further isolate the oases in southern Cyrenaica. This species occurs abundantly throughout western Libya in the provinces of Tripolitania and Fezzan. Presently, these populations in Libya are linked to those of the Nile Valley in Egypt by a series 118 U.S. NATIONAL MUSEUM BULLETIN 275 of rather discontinuous populations throughout the northern Chad and west-central Sudan. In the future, when more localities become represented by specimens, it is probable that a more clearly defined dispersal route, consisting of several overlapping populations, will be found to unite the Libyan populations with those of the type locality in the Nile Valley. Prior to the present study, Ellerman and Morrison-Scott (1951) included Algeria within the range of G. p. pyramidum, based, appar- ently, on specimens from El Golea and In Salah. It is now known that the range of the nominate subspecies is confined to Egypt (in- cluding Sinai) and Sudan as far south as Khartoum. The range of G. p. tarabuli thus is interposed between the areas of occurrence of these Algerian populations and the type locality. Such a discontinuous distribution for members of the same subspecies is untenable, and I suspect that these gerbils from central Algeria represent subspecies distinct from those in Libya and Egypt. Gerbillus pyramidum hamadensis, new subspecies Ho.uotyps. Adult male, skin and skull, USNM 321827, from 5 km E Derg, Tripolitania Province, Libya, obtained Nov. 14, 1961, by G. L. Ranck, original no. 886. SPECIMENS EXAMINED. Fifty-five, from Cyrenaica: 5 km W El Agheila, 1; from Triponitania: 5 km N Mizda, 3; 12 km W Sirte, 2; 15 km WNW Marble Arch, 3; 30 km S Bu Ngem, 2; 5 km E Derg, 13; 5 km S Socna, 15; Bir Fergian, 10 km S Soena, 17 (16 skin only). MEASUREMENTS. Averages and extremes of six adult males and five adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 240.2 (235-244), 228 (223-234), [244]; length of tail 141 (137-145), 131.4 (128-135), [145]; length of hind foot 30.2 (29-32), 31 (29-32), [29]; length of ear 14.8 (14-16), 15.2 (14-16), [16]; occipitonasal length of skull 31.6 (31-32), 30.5 (29.7-31.4), [32]; length of auditory bulla 11.7 (11.4-11.9), 11.5 (11.2-11.7), [11.6]; crown length of upper molariform toothrow 4.3 (4.1-4.4), 4.2 (44.4), [4.2]; greatest breadth across zygomatic arches 16.7 (15.7-16.9), 16.2 (15.8-16.8), [16.6]; least interorbital breadth 6.5 (6-6.8), 6.3 (6-6.6), [6.8]: breadth of rostrum at level of antorbital foramina 3.6 (3.5-3.8), 3.6 (3.5-3.8), [3.6], greatest length of nasals 12.3 (11.8-12.6), 11.7 (11.312), [12.6]. Draenosis. Upperparts Cinnamon-Buff grading to Clay Color and Tawny-Olive on rump and becoming paler on sides; entire dorsum lightly washed with brownish hairs which project appreciably beyond the paler colored underlying hairs; subauricular areas Cinnamon-Buff with slight suffusion of grayish-brown hairs; supraorbital, rostral, mystacial, circumoral, and pectoral areas pure white; postauricular RODENTS OF LIBYA 119 patches distinct and pure white; pinna of ear same color as dorsum, sparsely haired and with row of buffy hairs along anterior margin; vibrissae composed of nearly equal numbers of brown and white hairs; dorsal and ventral surfaces of fore and hind feet white, densely haired and each bearing five digits with claws; tail indistinctly bicolored, Pinkish Buff dorsally and Pale Pinkish Buff ventrally, and terminating in a conspicuous brownish-colored pencil; entire underparts white. Skull: Relatively small; rostrum wide; molariform teeth relatively large; anterior palatine foramina markedly narrow and slitlike; auditory bullae rather bulbous. Comparisons. From Gerbillus pyramidum pyramidum as known from several localities in Giza Province, Egypt, Gerbillus pyramidum hamadensis differs in markedly smaller size of body and skull, relatively smaller and more slitlike anterior palatine foramina, less ventrally inflated auditory bullae, less robust zygomata, and smaller lachrymals. This subspecies is much paler and uniform in dorsal color and has more prominent postauricular patches and lighter colored pencil. Compared with topotypes of Gerbillus pyramidum tarabuli, G. p. hamadensis is noticeably smaller in all cranial and external characters, being of comparable size only in crown length of molariform toothrows and breadth of rostrum. In color, members of this new subspecies are slightly paler, have a grayer cast owing to a greater suffusion of grayish hairs on dorsum, and have a pencil of a slightly lighter color. These gerbils can be readily distinguished from representatives of Gerbillus pyramidum hirtipes Lataste from Ain Sefra, southwestern Algeria, by paler dorsal color, longer and more thickly tufted tails, larger auditory bullae and molariform toothrows, and generally larger size of all other measurable cranial characters. In general body size and length of hind foot and ear, G. p. hamadensis resembles Gerbillus aureus nalutensis but differs markedly in having smaller anterior palatine foramina, longer posterior palatine canals, more robust zygomata, larger molariform teeth, longer and more tufted tail, paler and less varied dorsal color with less suffusion of black on rump, and larger size of all cranial measurements. Remarks. Members of this subspecies can be distinguished from all others in Libya by their conspicuously smaller size and paler dorsal color. Throughout the range of this subspecies, animals vary locally. Gerbils from 5 kilometers south of Socna, Tripolitania Province, are more strongly suffused with brown on the back and dorsum of tail, have slightly darker pencils, slightly longer and wider anterior palatine foramina, more gracile skulls, less prominent supraorbital ridges, and are slightly smaller in all cranial measurements. Two specimens, 322097 and 322098, from 30 kilometers south of Bu Ngem, Tripolitania Province, have slightly smaller anterior palatine foramina, but, in 120 U.S. NATIONAL MUSEUM BULLETIN 275 color, are indistinguishable from gerbils from Socna and Bir Fergian. Members of this subspecies from various localities in the coastal plain tend to have slightly larger, more bulbous auditory bullae. Those from 12 kilometers west of Sirte are also darker in dorsal color. This variation is well within the expected limits of a subspecies whose range includes such a large geographic area. The populations from Socna and Bir Fergian show only slight intergradation with G. p. tarabuli whose range is to the south. Gerbils from the type locality at Derg show no evidences of interbreeding with populations to the south. The high escarpments of the Hamada de Tinrhert in the west and the mountain ramparts of the Gebel es Soda and the Gebel el Harug el Asued in the east obviously have proven to be serious deterrents to gene exchange between populations of these gerbils, and thus the range of this subspecies is limited to the hamadas, coastal deserts, and coastal plain lying north of these barriers. In northwestern Tripolitania the range of this subspecies ap- parently does not attain the Mediterranean Coast. Three specimens from 5 kilometers north of Mizda constitute the northernmost record of occurrence of G. pyramidum in Libya. Farther north, Gerbillus aureus is the dominant gerbil and probably competes with and thus prevents G. pyramidum from occupying the coastal areas. Farther eastward, however, along the Gulf of Sirte, G. aureus is known only from Sirte, while G. p. hamadensis is known from several localities. EcoLoGiIcaL OBSERVATIONS. The type series was obtained from the rather denuded margins of a small wadi in the western portion of the Hamada el Hamra. This dry watercourse afforded scanty vege- tative cover, while rocky outcroppings interspersed with bare areas of sand and gravel were widespread. In the immediate vicinity of the wadi, Tamariz, Calligonum, and other types of shrubs were the dom- inant vegetation, but farther out on the hamada, smaller plants growing close together were commoner. The soil in this area consisted mostly of sand. Setzer (1957) describes the habitat at Socna and Bir Fergian as consisting of a sandy-clay substrate similar to hardpan, which re- sembles the desert playas of the Western United States. The collecting sites in the coastal plain near Sirte, Marble Arch, and El Agheila were characterized by dense plant cover and the soil in these areas also was sandy-clay. Large, permanent dunes supporting Calligonum characterized the habitat near Bu Ngem. Judging from the sandy character of these habitats, this subspecies always requires a sandy substrate. The name hamadensis refers to the hamada-like character of the habitat at the type locality and several other collecting sites of this subspecies. RODENTS OF LIBYA 121 Gerbillus pyramidum tarabuli Thomas Gerbillus pyramidum tarabult Thomas, Proc. Zool. Soc. London, vol. 2, pt. 1, p. 5, October 1902 (Sebha, Fezzan Province, Libya). SPECIMENS EXAMINED. Three hundred thirty-one, from FEzzan: Brach, 22, Edri, 12; Temenhint, 34; 4 km N Sebha, 10; 5 km NW Sebha, 8; 3 km NW Sebha, 10; Sebha, 19 (2 BM); 7 km SW Sebha, 5; 10 km SE Sebha, 1; El Abiad, 35 (3 skin only; 4 skeletons) ; Goddua, 15 (9 skull only); Meseguin, 33; Umm el Araneb, 14; Traghen, 12; 6 km N Murzuch, 26; 28 km E Murzuch, 3; Murzuch, 4; 12 km N Ghat, 1; Ghat, 11; El Gatrun, 46; El Barcat, 10. MEASUREMENTS. Averages and extremes of 17 adult males and 14 adult females from the vicinity of Sebha are, respectively: Total length 271.4 (261-289), 256.9 (246-277); length of tail 153.8 (143- 165), 145.3 (132-155); length of hind foot 33.1 (31-35), 31.9 (30-35) ; length of ear 16.2 (14-17), 15.3 (14-17); occipitonasal length of skull 34.1 (32.5-35.6), 32.9 (31.8-34.2); length of auditory bulla 11.9 (11.4-12.3), 11.6 (11.2-12.3); crown length of upper molariform toothrow 4.3 (4-4.5), 4.2 (3.9-4.5); greatest breadth across zygomatic arches 17.8 (17.2-18.6), 17.3 (16.7-17.8); least interorbital breadth 6.8 (6.5-7.4), 6.7 (6.3-7.1); breadth of rostrum at level of antorbital foramina 3.5 (3.3-3.8), 3.5 (3.3-3.8) ; length of nasals 13.4 (12.7—-14.3), 12.9 (12.4-13.5). Diaenosis. Upperparts ranging from Light Ochraceous-Buff to Ochraceous-Buff, becoming paler on sides and flanks; entire dorsum with grayish cast owing to alternate banding on individual hairs; this grayish hue more concentrated in middorsal region; postauricular and supraorbital patches conspicuous and white; rostral, mystacial, circumoral, and scapular areas, and entire underparts pure white; this white extending dorsolaterally beyond the venter and forming an abrupt line where it merges with the buffy color of the dorsum; inner and outer surfaces of pinna of ear sparsely haired and Warm Buff; eye ring black; vibrissae formed from about equal numbers of light and dark hairs; dorsal and ventral surfaces of fore and hind feet densely haired, each with five digits bearing claws; tail relatively long, indistinctly bicolored, Light Ochraceous-Buff above and Pale Ochrace- ous-Buff below, with prominent pencil (Wood Brown) extending along distal one-third of tail; dorsum of tail with light admixture of brownish hairs. Skull: Large and robust; zygomata heavy; anterior palatine foramina small; post palatine canals narrow and slitlike; braincase flattened; supraorbital bead prominent; auditory bullae narrow transversely and ventrally inflated. Comparisons. In the shape and proportions of the skull, topotypes of Gerbillus pyramidum tarabuli from the vicinity of Sebha, Fezzan Province, Libya, are indistinguishable from specimens of Gerbillus 285-134 O—68——_9 12 U.S. NATIONAL MUSEUM BULLETIN 275 pyramidum pyramidum Geoffroy, as known from Giza Province, Egypt. The nominate subspecies is significantly larger, however, in all external and cranial measurements, particularly in the breadth of the zygomatic arches and the length of the nasals. The two subspecies are separable primarily by differences in color, the nominate subspecies being noticeably darker in dorsal color with greater suffusion of dark- colored hairs. Typical G. p. pyramidum also have darker and more conspicuously bicolored tails, darker pencils, darker ears, darker and less conspicuous postauricular and supraorbital patches, and darker color around the entire circumorbital area (in many specimens of G. p. tarabuli, the suborbital and postauricular patches are almost pure white). From two specimens (BM, nos. 13.8.6.53 and 13.8.6.60) representing Gerbillus pyramidum hirtipes from Ain Sefra, southwestern Algeria, G. p. tarabuli is paler and less brilliant in dorsal color, has a longer tail with a more pronounced pencil, and is markedly larger in all other external and cranial measurements. For comparison with Gerbillus pyramidum hamadensis, see account of that subspecies. Remarks. In the original description, Thomas (1902) used the darker color of G. p. pyramidum to separate these two subspecies, but stated that, in the size and proportion of the skull, the two forms were somewhat comparable. Setzer (1957) stated that gerbils representing G. p. tarabuli were somewhat smaller but darker in color than those representing G. p. pyramidum from the Nile Valley of Egypt. These findings are in partial disagreement with mine, probably because the above comparisons were based on smaller series, as these workers had fewer specimens available at the time. Also Setzer included specimens from Socna and Bir Fergian, Tripolitania Province, within G. p. tarabuli. Gerbils from these localities are now known to represent a subspecies distinct from G. p. tarabuli and significantly darker in color. Ellerman and Morrison-Scott (1951) placed Gerbillus flowert Thomas in synonymy under G. p. tarabuli and thus extended the range of G. p. tarabuli to include portions of eastern Egypt and Sinai. Subse- quently, Setzer (1958) questioned such a wide distribution for a subspecies and designated Gerbillus pyramidum flowert as a separate subspecies based on its lighter color, more inflated auditory bullae, smaller molariform teeth, more laterally curved anterior palatine foramina, and less open pterygoid fossae. It is now known that G. p. tarabuli is not part of the mammalian fauna of Egypt but is limited in its distribution to the Libyan Fezzan; in all probability it occurs in RODENTS OF LIBYA 123 the Saharan Oases and in the vicinity of the Ahaggar Mountains of southeastern Algeria. Owing to the barriers provided by the Gebel es Soda, Gebel el Harug el Asued, and Hamada de Tinrhert, little, if any, outbreeding takes place with populations of G. p. hamadensis to the north and east. The vast Idehan Murzuch and Gebel Ben Ghnema prevent interbreeding with populations of gerbils to the south, so this subspecies has main- tained its genetic identity. Members of this subspecies from El Abiad and Temenhint are darker dorsally than those from nearby Sebha. Specimens from the vicinity of Murzuch, Goddua, Traghen, Umm el Araneb, and Meseguin show an orange-colored dorsal pelage. Animals from Ghat in the extreme southwestern portion of the Fezzan are darker and more variegated in dorsal color, with greater admixture of brownish hairs on the shoulders and rump, and have slightly larger skulls with more bulbous auditory bullae. Examples from El Gatrun, which is located a great distance from the type locality at Sebha, possess almost all the characters typical of tarabuli. These specimens, however, are slightly paler in dorsal color and have slightly larger auditory bullae and molariform teeth. Specimens from Brach and Edri in the Wadi es Sciati are more brilliantly colored (Salmon or Orange-Salmon) than any other representatives of this subspecies. This local variation in color is demonstrable in all populations of this gerbil throughout the Fezzan. In fact, it appears that these gerbils develop different colored pelage depending upon the type of substrate on and in which they live. This widespread variation is suggestive of a broad genetic constitution, which enables these gerbils to respond readily to the variety of conditions imposed by the prevailing en- vironment. An adult female, no. 322196, from El Gatrun is partially albinistic. This specimen is entirely white except for some brownish hairs on the distal portion of the tail and a faint suffusion of brown on the dorsum. EcoLoGICAL OBSERVATIONS. These gerbils are the commonest rodents of the Saharan Oases and prefer the sandy areas of the periphery and interior of the oases but also inhabit the vegetated wadis which link the various oases together. They occur sparingly in the margins of the hamadas wherever localized sandy areas are present but apparently do not inhabit the inner portions of these hamadas or the interior of the desolate sand seas. Their preferred habitat consists of areas of open sand and the numerous small vegetated dunes near the oases proper. Date palms occur in all Saharan oases, and these gerbils are frequently taken from 124 U.S. NATIONAL MUSEUM BULLETIN 275 among the fallen palm fronds and other debris at the bases of the trees. In the Fezzan, they were rarely taken from habitats lacking palm trees. On several occasions in the larger oases, these gerbils were purchased from local Arabs and presumably had been living in the mud-brick homes of these people. This is the only gerbil in Libya, known to me, which shows commensal tendencies. In their requirements, they are similar to Gerbillus gerbillus, but members of the latter species are less abundant and more widely distributed owing to their wider range of ecological tolerances. Other rodents which occur with G. p. tarabuli include Jaculus jaculus arenaceous, Gerbillus amoenus vivax, and Acomys cahirinus viator. 90 100 110 120 130 Ficure 22.—Statistical comparison of length of head and body of the subspecies of Gerbillus pyramidum: A, G. p. tarabuli; B, G. p. hamadensis. 29 30 31 32 33 34 35 36 Ficure 23.—Statistical comparison of occipitonasal length of the subspecies of Gerbillus pyramidum. Notation remains the same as in figure DL. RODENTS OF LIBYA 125 A —— 1 12 13 14 Ficure 24.—Statistical comparison of length of nasals of the subspecies of Gerbillus pyra- midum. Notation remains the same as in figure 22. Key to the Species of the Subgenus Dipodillus 1. Occipitonasal length less than 23mm ............ .. G. henleyi Occipitonasal length more than 23mm... . ee eee 2. Tail less than 90 mm; without terminal brush el Caaeuioreae . . G. Kaiseri Tail more than 90 mm; with prominent terminal brush and bicolored. . . 3 3. Occipitonasal length less than 27 mm; auditory bullae large and markedly inflated ventrally, anterior palatine foramina relatively short. G. amoenus Occipitonasal length more than 27 mm; auditory bullae small and not markedly inflated ventrally; anterior palatine foramina relatively long. G. campestris Gerbillus amoenus vivax (Thomas) Dipodillus vivax Thomas, Proc. Zool. Soc. London, vol. 2, pt. 1, p. 8, October 1902 (Sebha, Fezzan Province, Libya). GENERAL DISTRIBUTION OF SPECIES. Egypt, Libya, and probably Tunisia, Algeria, and Mauritania. DistrRIBUTION IN Lisya. Desert areas of Tripolitania and the Fezzan. In Cyrenaica known from the littoral deserts near the Gulf of Sirte, from Gialo Oasis, and the Gebel el Harug el Asued. SPECIMENS EXAMINED. Eighty-eight, from Cyrenaica: 5 km W El Agheila, 2; Gialo Oasis, 4; Gebel el Harug el Asued, 200 km SE Zella, 3; from TripoLiTania: 12 km W Zliten, 2; 12 km W Sirte, 1; 2 km SW Hun, 1;5 km S Soena, 3; from Frzzan: Edri, 11; El Abiad, 8 (2 skull only); Goddua, 15 (1 skin only, 12 skull only); Meseguin, 2; 6 km N Murzuch, 6; 28 km E Murzuch, 3; 20 km N Ghat, 1; Ghat, 16; El Gatrun, 4; El Barcat, 6. PUBLISHED RECORDS IN Lispya. Cyrenaica: Gheminez (Festa, 1921); Augila, Cufra, Gialo (de Beaux, 1932); Trrpotrranra: Ain Hammam (Thomas, 1902); El Gheddahia (Toschi, 1951); FEzzan: Sebha (Thomas, 1902); Ghat (Toschi, 1951). 126 U.S. NATIONAL MUSEUM BULLETIN 275 EL SBs Nek Li KILOMETERS \ ia nT Gerbillus amoenus vivax Figure 25.—Distribution of Gerbillus amoenus vivax. Circles indicate specimens examined; triangle indicates published record. MEASUREMENTS. Averages and extremes of 10 adult males and the measurements of 3 adult females from Goddua, Fezzan Province, are respectively: Total length 202.2 (187-213), 203, 200, 202; length of tail 112.9 (97-124), 113, 110, 115; length of hind foot 23.2 (22-23), 23, 23, 23; length of ear 12.4 (12-13), 12, 12, 13; occipitonasal length of skull 25.6 (25.2-26.3), 26.8, 25.3, 26.4; length of auditory bulla 9.7 (9.5-10.1), 9.7, 9.6, 9.8; length of upper molariform toothrow 3.3 (3.2-3.4), 3.3, 3.4, 3.4; greatest breadth across zygomatic arches 13.7 (13.4-14.5), 14.5, 13.6, 13.8; least interorbital breadth 4.6 (4.4—4.8), 4.7, 4.3, 4.5; breadth of rostrum at level of antorbital foramina 2.7 (2.5-2.9), 2.9, 2.7, 2.7; length of nasals 9.4 (9.3-9.7), 10.4, 9.4, 10.1. Diagnosis. Upperparts grading from Cinnamon-Buff to Clay Color, becoming paler on sides owing to suffusion of white; entire dorsum with uniform admixture of brown; plumbeous underfur exposed on dorsum in most specimens; postauricular patches conspicuous and white; pelage around ears and eyes subdued in color, approaching Light Buff, and strongly suffused with gray; a distinct grayish patch (typical of all members of this species) between the base of the pinna RODENTS OF LIBYA 127 of the ear and eye; rostral and circumoral areas Light Buff; pinna sparsely haired and with small tuft of buffy hairs on anteroventral margin; inner surface of pinna Ochraceous-Buff basally, becoming darker distally and on outer surface approaching Light Grayish Olive; vibrissae relatively short and formed of both light and dark hairs; dorsal surfaces of forelegs, hindlegs, feet, and entire underparts white, the latter, in some specimens, lightly suffused with Buff; fore and hind feet each with five digits bearing claws; palmar and plantar surfaces naked, the latter with six metatarsal tubercles; tail relatively long for the species, sparsely haired with short, hispid hairs, moderately tufted terminally, and in most specimens, distinctly bicolored Hair Brown to Wood Brown dorsally and ranging from Light Buff to almost white ventrally; the dorsum of the tail appears particolored owing to the interspersion of light and dark hairs and to exposure of the pale ground color from beneath; this variegated character of the tail is typical. Skull: Relatively large and robust; auditory bullae markedly large, bulbous and inflated ventrally; basioccipital narrow and rod- shaped anteriorly, thus forming distinct elliptical posterior lacerated foramina between it and the auditory bullae; anterior palatine foramina short and rectangular; zygomata relatively heavy with tendency to bow outward posteriorly; braincase moderately domed. Comparisons. Near topotypes of Gerbillus amoenus vivax from Goddua, Fezzan Province, Libya, differ from two topotypes of Gerbillus amoenus amoenus (de Winton) from El Aiyat, Mit Riheina, Giza Province, Egypt, in having larger and more robust skulls, noticeably larger, more bulbous and more ventrally inflated auditory bullae, heavier zygomata, wider zygomatic breadth, slightly larger molariform teeth, and longer nasals. Specimens from Libya are also paler in dorsal color, larger in total length, and have longer and slightly more tufted tails. Cranially, representatives of G. a. amoenus from Wadi Natroun, Western Desert Governorate, Egypt, are appreciably larger than the two topotypes from Giza Province and are comparable to specimens of G. a. vivax but differ in having shorter and less tufted tails and markedly smaller and less inflated auditory bullae. Another large series of G. a. amoenus from near Faiyum, Egypt, has the smallest auditory bullae of any of the specimens examined from Egypt and, in this character alone, can easily be distinguished from those of G. a. var from Libya. This subspecies resembles Gerbillus nanus nanus Blanford from Kerman Province, Iran but can be distinguished from the latter by much shorter tail, lighter (less grayish) dorsal color, smaller cranial size, noticeably smaller anterior palatine foramina, and markedly smaller and less inflated auditory bullae. 128 U.S. NATIONAL MUSEUM BULLETIN 275 From a single specimen of Gerbillus mackilligini (Thomas) from Wadi Kansisrob, Sudan Government Administrative Area, Egypt, specimens of G. a. vivax are noticeably smaller in overall size, more variegated in dorsal color, and have shorter, more particolored and less tufted tails, smaller hind feet, smaller and less inflated auditory bullae, shorter anterior palatine foramina and posterior palatine canals, less expanded braincases, and are smaller in all measurable cranial characters. Compared to Gerbillus campestris dodsoni, G. a. vivax is much smaller cranially and in overall size, has a noticeably shorter and less tufted tail, considerably larger and more inflated auditory bullae, and much shorter anterior palatine foramina. Remarks. Originally, Thomas (1902, p. 8) described Dipodillus vax from Sebha, Fezzan Province, Libya, and stated that it was closely related to Dipodillus quadrimaculatus Bodenheimer and Dipodillus amoenus de Winton of the D. quadrimaculatus group of Egypt but differed from both by its decidely larger auditory bullae, narrower basioccipital, and more uniform ‘‘ochraceous buffy’ color. He thus considered D. vivax as distinct from D. amoenus and regarded D. vivax as the Tripolitanian representative of the quadrimaculatus group of Kgypt. Later, Ellerman and Morrison-Scott (1951), Toschi (1954), and Setzer (1957) regarded D. amoenus and D. vivax as conspecific but included them as subspecies of Gerbillus dasyurus (Wagner), whose range had previously been limited to Sinai and areas to the north and east. The above workers had only a few specimens, and their assignments probably were based largely upon geographic grounds. In the present study, large series of topotypical G. dasyurus from Sinai and G. amoenus from Egypt are available; the two groups were more critically compared, and the following differences are noted: Specimens of G. dasyurus are significantly larger in all cranial and external measurements, have longer, denser, and more lustrous fur, appear more variegated dorsally, and have longer and noticeably more tufted tails, more inflated braincases, relatively narrower rostra, longer and more slitlike anterior palatine foramina and wider basioc- cipitals. It is evident that G. amoenus is a species distinct from G. dasyurus and that the latter is confined, as was previously thought, to areas east of the Nile River. Toschi (1954) assigned specimens from Gheminez to G. dasyurus amoenus (= G. amoenus amoenus) and those from other widely scattered localities, including Cufra Oasis, to @. dasyurus vivax (=G. a. vivaz). Setzer (1957), with reservations, included the few specimens available to him within the subspecies G. a. vivar and did not recognize the nominate subspecies as occurring in Libya. RODENTS OF LIBYA 129 Wassif (1956), in reviewing the dipodils of Egypt, recognized that gerbils representing G. amoenus and G. dasyurus were not of the same species and reinstated the former as a full species with a range con- fined to Egypt west of the Nile. He predicted that specimens from Tripolitania and other localities in Libya also probably represented a variety of G. amoenus. The present author is in agreement with Wassif in considering G. amoenus as a full species, and G. dasyurus is no longer considered as a part of the Libyan mammalian fauna. Specimens from the Fezzan are slightly larger in size of body, and their skulls have slightly larger and more inflated auditory bullae than those from Tripolitania and Cyrenaica. Within the Fezzan, the various populations are remarkably similar in cranial and external characters. Specimens from El Gatrun are slightly larger than topo- typical specimens from near Sebha, and a large series from Ghat and El Barcat are correspondingly smaller. To the north in Tripoli- tania, specimens from Zliten and Socna are comparable in size to typical G. a. vivax but have somewhat smaller auditory bullae. Specimens from farther east in Cyrenaica and nearer the type locality of G. a. amoenus are appreciably smaller in size and possess the smallest auditory bullae of any representatives of this subspecies in Libya. This diminution in bullar size in these easternmost populations of gerbils suggests intergradation with G. a. amoenus. A gradient, extending from west to east and showing progressive decrease in size and degree of inflation of the auditory bullae, is apparent in popula- tions of this gerbil in Libya and Egypt. Gerbils with small auditory bullae from the Nile Delta thus represent the easternmost limits of expression of this character, and those with larger auditory bullae from the Fezzan are near the westernmost limits of this character gradient. It appears that the subspecies G. a. amoenus and G. a. vwax actually represent the two extremes in this clinal gradient. It is not uncommon for populations at each end of a cline to develop dissimilarities of sufficient magnitude to warrant designation as distinct subspecies, especially when the clinal character extends over such a wide geographic area. While recognizing that the foregoing variation and clinal pattern exists within and between populations of this gerbil in Libya, and even though the easternmost populations show some characters typical of G. a. amoenus, I prefer to assign all of the specimens from Libya to G. a. vivaz. Four specimens from Biskra and a single specimen from Beni Abbes, Algeria, are within the geographic range ascribed to Gerbillus garamantis (Lataste). In cranial characters, these specimens are strikingly similar to those of G. a. vivax from western Tripolitania and the Fezzan. In cranial measurements, however, gerbils from Libya, 130 U.S. NATIONAL MUSEUM BULLETIN 275 including near topotypes of G. a. vwaxr from Goddua, Fezzan, are slightly smaller in length of skull and have slightly shorter nasals and anterior palatine foramina. The length of the skull of the type specimen of G. garamantis, as given by Lataste (1881), is also larger than typical G. a. viraz. Gerbils from both countries agree closely in external measurements, except for the slightly longer tail in those from Libya. In color, the populations are almost identical, but speci- mens from Algeria have longer, more lustrous, silkier fur. This character is particularly striking in the specimen from Beni Abbes. The specimens from Biskra differ in having appreciably longer and more inflated auditory bullae. The foregoing differences are not of sufficient magnitude to distinguish species but are more typical of the subtle characters used to distinguish populations at the infraspecific level. Furthermore, the enlarged auditory bullae of the specimens from Biskra probably represent an extension of the east-west cline apparent in populations of @. a. amoenus and G. a. vivax to the east. When the Algerian populations have been studied more thoroughly and topotypical material from Ouargla becomes available for com- parison, these gerbils in Algeria and Libya, which are currently known as G. garamantis and G. amoenus, respectively, probably will be regarded as conspecific and differ only as subspecies. Because of priority, the current G. amoenus will become a synonym of G. gara- mantis or be relegated to subspecific rank under the latter. When Lataste named G. garamantis in 1881, Dipodillus campestris (=Gerbillus campestris) and Gerbillus simoni Lataste were the only North African gerbils known within the dipodil group. Comparative specimens were largely unavailable from Libya and Egypt, and at that time, these Algerian specimens were clearly distinct from all others available to him. Ellerman and Morrison-Scott (1951) included G. garamantis as a subspecies of Gerbillus nanus and thus extended the range of the species far westward along North Africa. These Algerian populations were several thousand miles distant from the nearest representatives of G. nanus east of the Nile River. The above authors offered no explanation for this great hiatus in distribution of members of the same species. Setzer (1952) assigned three specimens from Kom Aushim, Giza Province, Egypt, to Gerbillus nanus gara- mantis but thought it unlikely that gerbils from the Nile Valley and Algeria belonged to the same subspecies. Wassif (1956) referred these specimens from Kom Aushim to G. a. amoenus and suspected that G. nanus did not occur in Egypt. The present study indicates that G. nanus is also not present in the mammalian fauna of Libya. EcoLoGicAL OBSERVATIONS. These dipodils occur in virtually all types of habitats in Libya. Specimens obtained at Ghat, Edri, El Gatrun, Meseguin, and near Murzuch came from areas of loose sand RODENTS OF LIBYA 131 covered by fallen fronds at the bases of date palms. At Goddua this species was taken from the loose sand of the palm groves and the sandy-clay soils of other agricultural areas within the oasis. The specimens from the Gebel el Harug el Asued were collected from rather impervious clay soils in a badly eroded large wadi. At other localities in Libya these gerbils were obtained in habitats ranging from the dense plant cover of the coastal plain to almost barren hamadas. They seem to prefer areas of loose sand or substrates of a sandy char- acter; only rarely are they found in large, permanent dune areas. The collection of specimens of this species was fortuitous, and their presence in a given area could never be predicted with certainty. Adequate series were obtained only after several days of continuous trapping. In many areas in Libya, members of this species occur sympatrically with those of other species of gerbils, but they are almost always less abundant. Gerbillus campestris Leyaillant Gerbillus campestris Levaillant, Atlas Expl. Sci. Alg. Mamm. pl. V, fig. 2., 1857 (Philippeville, Province of Constantine, Algeria [Lataste, 1881)). GENERAL DISTRIBUTION OF SPECIES. Western and coastal Egypt; Libya, Algeria, Morocco; range probably also includes northern por- tions of Sudan, Chad, Niger, and Mauritania. DistTRIBuTION IN LisyaA. Widespread throughout Cyrenaica, Trip- olitania, and the Fezzan (currently unknown from Gialo Oasis). DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Gerbillus campestris brunnescens. CyRENAICA: Cyrenaican Plateau and adjacent Mediterranean littoral. Gerbillus campestris dodsoni. CyRENAICA, TRIPOLITANIA, and the Frzzan: Widespread throughout Tripolitania and the Fezzan, but in Cyrenaica is limited to the southern oases of Tazerbo and Bzema. Gerbillus campestris haymani. Cyrenatca: Vicinity of Giarabub and Bahr el Tubat. Gerbillus campestris patrizii. Cyrpnatca: El Hauuari and El Giof of Cufra Oasis. Gerbillus campestris wassifi. CYRENAICA: Coastal plain of extreme northeastern Cyrenaica. PUBLISHED RECORDS IN [,BYA. CyRENAICA: Giarabub (de Beaux, 1928); El Giof (de Beaux, 1932); Triponiranta: Wadi Agarib, Ain Hammam, Wadi Nefed, Sirte, Tamari-Ferdjan (Thomas, 1902); Frzzan: Goddua, Umm el Abid (Thomas, 1902). Comparisons. Gerbillus campestris can be distinguished readily from the other dipodils in Libya by its much larger size, longer anterior palatine foramina, and markedly smaller and less inflated auditory bullae. 132 U.S. NATIONAL MUSEUM BULLETIN 275 LIBYA KILOMETERS 4 Gerbillus campestris . |. brunnescens 2. dodsoni 3. haymani 4. patrizii 5. wassifi Figure 26.—Distribution of the subspecies of Gerbillus campestris. REMARKS. Setzer (1957) referred all specimens of this gerbil from Libya to Gerbillus campestris dodsoni. Gerbillus campestris patrizir from Cufra Oasis was placed in synonymy under G. c. dodsoni, and specimens from the Cyrenaican Plateau were likewise included with this subspecies. In a later paper, Setzer (1958) described G. c. wassift (p. 208) from the Egyptian littoral and G. c. haymani (p. 209) from Siwa Oasis of western Egypt. Both of these type localities are located near the Libyan frontier. Currently, many more localities in Libya are represented by specimens, and the taxonomic relationships can be investigated more thoroughly. Gerbils from the coastal plain of northern Cyrenaica are referable to G. c. wassifi, and those from Bahr el Tubat, near Giarabub, represent G. c. haymani. The specimens from the Cyrenaican Plateau, formerly referred to G. c. dodsoni by Setzer, have been supplemented with additional series from the nearby coastal plain and are here recognized as a new subspecies, G. ¢. brun- nescens, distinct from dodsoni. Furthermore, G. c. patrizii has been re- instated as a subspecies based upon the critical examination of newly acquired specimens from El Hauuari and El] Giof of Cufra Oasis. The range of G. c. dodsoni is extended to include all of Tripolitania, most RODENTS OF LIBYA 133 of the Fezzan, and a large portion of southern Cyrenaica. As a result of the present study, five subspecies of G. c. campestris are now known to occur in Libya. EcoLoGIcAL OBSERVATIONS. Members of this species are the most widely distributed of ali Libyan rodents and occur in virtually all habitats. In the larger oases where sandy areas and date palms are widespread, gerbils belonging to the subgenus Gerbillus are more abundant, and representatives of G. campestris are confined more to the mesic habitats of the sedge pockets in the interior of the palm groves or occur beyond the oasis proper in the zone of tamarix and acacia. Apparently, G. campestris is not able to compete with these sand-loving gerbils and is forced to inhabit these marginal habitats. In a few cases, however, these gerbils occupied all habitats within the oasis. Rocky areas appear to be preferred above all others; wherever cliffs, rocky outcroppings, or talus are present, these rodents occur in abundance. Gerbillus campestris brunnescens, new subspecies Hototyre. Adult male, skin and skull, USNM 302180, from 5 km SE Derna, Cyrenaica Province, Libya; obtained Nov. 9, 1955, by H. W. Setzer, original no. 2724. SPECIMENS EXAMINED. One hundred twenty-one, from CYRENAICA: 27 km E Apollonia, 3; 11 km SW Susa (=Apollonia), 5; 12 km SW Apollonia, 2 (1 skin only); 12 km S Apollonia, 2; 5 km NW Labrag, 6 (1 skin only); 4 km W Labrag, 1; 12 km NW Gubba 3 (1 skin only); 3 km E Derna, 8; 5 km SE Derna, 27 (1 skin only); Wadi el Kuf, 13 km WSW Messa, 7; 10 km SW El Faidia, 6; 7 km NE Slonta, 1; 5 km W Tocra, 29 (1 skin only); 20 km SW Tocra, 16; 10 km N Gerdes, 3; 2 km N Coefia, 2. MEASUREMENTS. Averages and extremes of 15 males and 9 females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 244.8 (228-262), 236 (223-252), [248]; length of tail 143.1 (132-150), 137.8 (127-152), [148]; length of hind foot 28.2 (27-30), 27.3 (27-28), [28]; length of ear 17.6 (17-19), 17.2 (17-18), [18]; occipitonasal length of skull 30.3 (28.9-31.6), 29.5 (28.9-30.2) [30.2]; length of auditory bulla 9.3 (8.9-9.7), 9.3 (9-9.5), [9.3]; crown length of upper molariform toothrow 3.9 (3.8-4.1), 4 (3.9- 4.2), [3.9]; greatest breadth across zygomatic arches 15.6 (14.7-16.6), 14.9 (14.4-15.2), [15.5]; least interorbital breadth 5.5 (5.2-5.9), 5.4 (5.2-5.7), [5.7]; breadth of rostrum at level of antorbital foramina 3.2 (3.1-3.4), 3.2 (3.1-3.3), [3.3]; greatest length of nasals 11.6 (11-12.8), 11.3 (10.9-11.7), [11.2]. Diacnosis. Upperparts Sudan Brown becoming paler on sides and scapular areas; all parts of dorsum with strong suffusion of blackish- 134 U.S. NATIONAL MUSEUM BULLETIN 275 brown hairs, being particularly concentrated on rump; subauricular region with strong admixture of blackish hairs; preauricular and post- auricular patches conspicuous and white; eye ring black; mystacial, circumoral, and pectoral areas Light Buff; pinna of ear sparsely haired, Ochraceous-Tawny basally and Mummy Brown distally, and with distinct tuft of grayish hairs on anteroventral margin; vibrissae relatively short and formed from equal numbers of light and dark hairs; forearm with distinct buffy patch and otherwise white throughout; hindlegs with conspicuous Dark Olive patch on ventral surface, otherwise white throughout; fore and hind feet white, each bearing five digits with claws; palmar and plantar surfaces of fore and hind feet entirely naked, the latter Mars Brown in color; underfur of all dorsal pelage Deep Plumbeous; entire underparts white with faint buffy suffusion in some specimens; tail relatively long, distinctly bi- colored, Verona Brown dorsally, almost white ventrally and slightly penicillate. Skull: Small and gracile; auditory bullae small and mildly inflated ventrally; zygomatic breadth narrow and zygomata fragile; braincase slightly vaulted. CoMPARISONS. Compared with a single specimen of Gerbillus campestris campestris from near Oran, Algeria, the type and paratypes of Gerbillus compestris brunnescens are paler in dorsal color, have slightly more tufted tails, much longer tails, more suffusion of dark color around eyes, larger bodies, and cranially are larger and more robust, with wider rostra, wider interorbital breadths, and larger cranial measurements, especially length of the upper molariform toothrow. Members of this new subspecies may be distinguished from topo- types of G. c. dodsoni from Ain Hammam, Tripolitania Province, and a large series from Brach, Fezzan Province, by their darker (more brownish) and more uniform dorsal color, longer and markedly less tufted tails, greater overall length of body, slightly shorter ears, less robust skulls, markedly smaller and less inflated auditory bullae, and more vaulted braincases. Compared with topotypical G. c. haymani from Siwa Oasis, Western Desert Governorate, Egypt, and a small series representing haymani from Bahr el Tubat, Cyrenaica Province, Libya, G. c. brunnescens is markedly darker in dorsal coloration, has a less tufted tail, smaller hind feet and ears, and a more gracile skull which is markedly smaller in all cranial shericbers, being closest in the width of the rostrum and the length of the upper molariform toothrow. From topotypes of G@. c. wassifi from the Libyan Plateau, near Salum, Western Desert Governorate, Egypt, G. c. brunnescens differs in its darker dorsal color, smaller overall size, relatively longer tail, smaller ears, smaller skull, narrower anterior palatine foramina, narrower RODENTS OF LIBYA 135 zygomatic breadth, shorter nasals, and shorter and less inflated auditory bullae. This new subspecies can be readily distinguished from Gerbillus campestris patrizit by its darker, more uniform dorsal coloration and noticeably larger size of body and cranium, being comparable only in length of the auditory bullae and length of upper molariform toothrow. Remarks. Members of this subspecies can be distinguished from all others in Libya by their darker, more uniform dorsal color and somewhat longer and less tufted tails. Setzer (1957) assigned specimens from the Cyrenaican Plateau to G. c. dodsoni. His assignment was based solely upon some notes characterizing the type specimen of G. c. dodsoni in the British Museum and upon favorable comparison with the original description of Dipodillus dodsoni as given by Thomas (1902). In the present study, more specimens are available from the Cyrenaican Plateau, and topotypes of dodsoni, in addition to large series from various other localities in Libya, are on hand. Thus, the taxonomic status of these specimens from the Cyrenaican Plateau can be determined more accurately. The range of this subspecies is confined to the uplands of the Cyre- naican Plateau and the adjacent littoral areas. Intergradation between G. c. brunnescens and G. c. wassifi of extreme northeastern Cyrenaica and coastal Egypt is apparent in specimens from the coastal areas near Derna and Apollonia. In their pale dorsal color, large cranial size, and wide anterior palatine foramina, they resemble G. c. wassifi, but in the size and degree of inflation of the auditory bullae and in all other cranial characters, they are closer to G. c. brunnescens and are assigned to this subspecies. The vast areas of central Cyrenaica, in- cluding Gialo Oasis and the Gebel el Harug el Asued, and the littoral deserts and coastal plain along the Gulf of Sirte are not represented by specimens and thus create a decided gap in distribution. The two specimens from near Coefia, representing the southernmost record of distribution for G. c. brunnescens, show no evidences of gene exchange with G. c. dodsoni, whose range is farther to the south and west. Within populations of this subspecies in Cyrenaica, local variation in dorsal color is apparent. The pattern of this color gradient is too irregular to suggest clinal variation and probably a genetic response to the local character of the substrate. Gerbils from the coastal plain, where the soils are darker, tend to be darker and more uniform in dorsal color than those from the plateau. This dark dorsal color reaches its extreme in specimens from the vicinity of Tocra. ECOLOGICAL OBSERVATIONS. These rodents are the most abundant gerbils in the Cyrenaican Plateau and were regularly taken in trap- lines. Other dipodils were collected on the plateau, but they were fewer in number. Members of this subspecies occupy almost all of the 136 U.S. NATIONAL MUSEUM BULLETIN 275 available habitats on the plateau and coastal plain ranging from the exposed uplands with a scanty vegetative cover to the dense plant cover of the larger wadis. They are perhaps most abundant in the chaparral vegetation of the hillsides and throughout the dense vegeta- tion of the coastal plain. They also occupy the rocky cliffs and talus of the wadis and the rocky outcroppings along the coastal escarpments. They were never collected from coastal dunes or other habitats com- posed exclusively of sand. In these habitats they are supplanted by the more sand-loving Gerbillus eatoni. The name brunnescens, meaning dark, dusky, or brown, alludes to the brownish color of the dorsal pelage of members of this subspecies. Gerbillus campestris dodsoni (Thomas) Dipodillus dodsoni Thomas, Proc. Zool. Soc. London, vol. 2, pt. 1, p. 7, October 1902 (Ain Hammam, Tripolitania Province, Libya). SPECIMENS EXAMINED. One hundred thirty-seven, from Cyr- ENAICA: Tazerbo Oasis, 44; El Gezira (Tazerbo Oasis), 15; Bzema Oasis, 9 (1 skin only); from Tripotrranta: 5 km W Cussabat, 6; 20 km N Gharian, 3; 20 km E Rumia, 2; 12 km S Chicla, 2; Ain Hammam, 3 (BM); Gebel es Soda, 60 km S Soena, 4; from FEzzan: Brach, 31; Temenhint, 2 (1 skull only); 75 km W Ubari, 2; 20 km N Ghat, 1; Ghat, 1. MPASUREMENTS. Averages and extremes of 17 adult males and 21 adult females from Tazerbo Oasis, Cyrenaica Province, are, respectively: Total length 223.1 (205-238), 222.9 (211-254); length of tail 126.6 (118-140), 127.9 (111-148); length of hind foot 26.9 (25-29), 26.7 (25-28); length of ear 16 (15-17), 15.7 (14-17); oc- cipitonasal length of skull 30.4 (28.6-31.7), 30.5 (28.7-32.1); length of auditory bulla 9.7 (9.2-10.1), 9.7 (9.2-10.1); crown length of upper molariform toothrow 3.9 (3.7-4.2), 4 (3.8-4.3); greatest breadth across zygomatic arches 15.8 (14.6-16.5), 16 (15.1-16.5); least in- terorbital breadth 5.5 (5-6), 5.4 (4.7-6); breadth of rostrum at level of antorbital foramina 3.2 (3-3.4), 3.2 (3-3.4); length of nasals 11.9 (10.6-12.6), 11.4 (11-13). Diaenosts. Dorsal color ranging from Cinnamon-Brown, Sudan Brown, and Verona Brown to Ochraceous-Tawny, all frequently occurring in animals of the same local population; most specimens with strong suffusions of darker hairs on dorsum, resulting in a varie- gated or marbled appearance; other specimens uniformly colored; in most specimens postauricular patches indistinct and suffused with buffy hairs, and in others almost white; circumorbital areas generally Light Buff with admixture of brownish hairs, in some specimens darker and approaching color of dorsum; eye ring black; scapular regions heavily suffused with brownish or buffy hairs, which RODENTS OF LIBYA Lae sometimes extend to forearm; vibrissae relatively long and longer hairs dark brown and lighter ones usually white; pinnae of ears sparsely haired, becoming darker distally, ranging in color from Drab to Fuscous; circumoral areas, dorsal surfaces of forelegs, hind- legs, feet, entire underparts and, in some specimens, ventral surface of tail pure white; fore and hind feet with five digits bearing claws; palmar and plantar surfaces naked, the latter with six metatarsal tubercles; tail medium in length with distal one-third forming prom- inent brownish pencil; tail usually conspicuously bicolored varying from almost pure white to Avellaneous ventrally and from Sayal Brown to Warm Sepia dorsally ; this bicoloration less striking in darker specimens. Skull: Medium in size; frontal bone with a distinct fossa near the nasofrontal suture; zygomata strong and bowing outward posteriorly; braincase flattened; auditory bullae noticeably large and bulbous. CoMPARISONS. Compared to a single adult specimen of Gerbillus campestris campestris from near Oran, Algeria, specimens from Brach, Fezzan Province, and Tazerbo Oasis, Cyrenaica Province, are larger in overall size, have markedly longer and more terminally tufted tails, darker, more variable, variegated dorsal color, longer vibrissae, and larger measurable cranial characters. In dorsal color, these same specimens resemble topotypes of Gerbillus campestris rozsikae Thomas from Biskra, Algeria but differ from this subspecies in being larger in size of body and cranium and having longer, more conspicuously tufted tails, shorter anterior palatine foramina, and larger, more ventrally inflated auditory bullae. For comparisons of these gerbils from Brach and Tazerbo Oases with Gerbillus campestris brunnescens, G. c. wassifi, G. c. haymani, and G. c. patrizii, see accounts of those subspecies. Remarks. These specimens from Tazerbo and Brach, although clearly referable to G. c. dodsoni, differ from topotypes of the latter from Ain Hammam, Tripolitania Province, in having slightly darker dorsal coloration, more tufted tails, larger auditory bullae, wider rostra, and slightly wider interorbital region. Other representatives from various localities throughout Cyrenaica, Tripolitania, and the Fezzan also differ from topotypical G. c. dodsoni in subtle characters. These tenuous differences, however, do not exceed the variation expected within populations of the same subspecies. In 1902, Thomas described Dipodillus dodsoni (=Gerbillus campes- tris dodsoni) from Ain Hammam, Tripolitania Province, Libya, as distinct from Dipodillus campestris of the coastal areas of Algeria. The two species were distinguished by the larger size, more ‘‘desert colour,” and more prominently tufted tail of D. dodsoni. He assigned specimens, now known as Gerbillus campestris rozsikae, from Biskra, 285-134 O—68——10 138 U.S. NATIONAL MUSEUM BULLETIN 275 Algeria, to D. dodsoni and included all of Tripolitania and portions of the Fezzan within the range of D. dodsoni. The present work indicates that the range of G@. c. dodsoni is confined to western and central Libya and perhaps includes portions of eastern Algeria and Tunisia. Gerbils from the Gebel es Soda and the Gebel Nefusa are paler in dorsal color and have larger, more inflated auditory bullae than those from other localities in Tripolitania. Representatives of this subspecies from near Cussabat are darker in dorsal color and have less tufted tails than those of populations to the south. Specimens from near Ghat, Temenhint, and Ubari, in the Fezzan, have markedly more tufted tails (sometimes the pencil occupies one-half the total length of the tail), less streaked dorsal pelage, slightly larger auditory bullae, and are slightly larger in general size than those from Brach farther north. Except for slightly larger auditory bullae in gerbils from the Fezzan, those from Tazerbo Oasis in Cyrenaica and from Brach in the Fezzan, although widely separated geographically, are indistinguishable in color and cranial characteristics. All of the specimens here assigned to G. c. dodsoni possess prominently tufted tails and have large, inflated auditory bullae, which are the most diagnostic characters of this subspecies. No specimens of G. campestris are available from the oasis of Gialo, but because this species is widespread to the north and occurs abun- dantly in the remote oases farther to the south in Cyrenaica, probably they occur here also. Gialo is located between the ranges of G. c. brunnescens and G. c. dodsoni, and when specimens of G. campestris become available from Gialo, they may possess characters of both subspecies. With the exception of the large series from Brach, only six additional specimens of this subspecies were obtained from the Fezzan. These few specimens do not provide a reliable index to their actual numbers. Suitable habitat is of widespread occurrence throughout the various wadis, serirs, and oases of the Fezzan, and any barriers to dispersal are of local extent. It is probable that these gerbils occur in all the major oases in the Fezzan and also those of southern and central Cyrenaica. This species has not been recorded from the Tibesti Mountains but probably occurs there. Evidences of gene exchange with other subspecies are lacking, probably owing to the largely disjunct distribution of this subspecies and also to the lack of specimens from most of the marginal areas; hence, comparisons are not possible. Intergradation with G. c. brun- nescens probably takes place somewhere along the littoral areas of the Gulf of Sirte, and gene exchange with G. c. rozsikae and the nominate subspecies may take place somewhere among populations RODENTS OF LIBYA 139 of these gerbils in eastern Tunisia and Algeria. Members of this subspecies have no physical contact with those of G@. c. wassifi of the Mediterranean littoral, and it is doubtful if gene flow is a com- mon occurrence between animals of G. c. dodsoni and G. c. haymani, whose range includes the isolated depressions and the oases of Giara- bub and Siwa far to the east. EcoLoGICcAL OBSERVATIONS. In the Gebel Nefusa, these gerbils inhabit the crevices and fissures of the rocky outcroppings along canyons that descend onto the coastal plain. Those from the Gebel es Soda were taken among the coarse extrusions of volcanic material near the highest point of the gebel. The large series from Brach was obtained from moist areas supporting dense growths of sedges and grasses associated with agriculture. At Temenhint Oasis, two speci- mens were obtained from the sand surrounding date palms. Near Ubari, two additional specimens were obtained from the practically denuded margins of a shallow wadi which supported sparse growths of acacia and occasional dried grasses. Near Ghat the habitat was typical “hamada”’ desert without any visible plant cover. At the oases of Bzema and Tazerbo, these gerbils occur abundantly in the dense pockets of sedges that occupy the low-lying interior portions of the palm groves. In fact, at Tazerbo, trap yields exceeded 85 percent and were the highest recorded for Libya. A specimen from Tazerbo Oasis, an adult male, 325387, is strikingly different in color from other specimens from this locality. It is uni- formly gray throughout except for the tail, which is strongly suffused with brown. One specimen, an adult female, 325403, from Bzema Oasis is heavily suffused with white on the dorsum, the tail has uniform admixtures of white hairs throughout, and the ears and feet are extremely pale. This specimen is the only example of albinism or partial albinism observed in this species. Gerbillus campestris haymani Setzer Gerbillus campestris haymani Setzer, Journ. Egypt. Publ. Health Assoc., vol. 33, no. 6, pp. 208-209, 1958 (Siwa Oasis, Western Desert Governorate, Egypt). SPECIMENS EXAMINED. Four, from Bahr el Tubat, Cyrenatica Province, Libya. MEASUREMENTS. Measurements of two adult males, 325501 and 325502, and two adult females, 325503 and 325504, from the above locality are, respectively: Total length 268, 240, 239, 241; length of tail 160, 141, 136, 140; length of hind foot 29, 30, 27, 28; length of ear 17, 17, 17, 17; occipitonasal length of skull 32, 31.2, 31.5, 31.5; length of auditory bulla 10.3, 9.8, 10, 10.1; length of upper molari- form toothrow 3.9, 3.8, 4.2, 4.2; greatest breadth across zygomatic 140 U.S. NATIONAL MUSEUM BULLETIN 275 arches 16, 16.4, 16.5, 16; least interorbital breadth 5.6, 5.4, 5.9, 5.5; breadth of rostrum at level of antorbital foramina 3.1, 3.1, 3.4, 3.3; length of nasals 12.6, 13.2, 12.5, 12.5. Diaenosis. Middorsal region Clay Color to Tawny-Olive, becoming paler on sides and flanks and approaching Cinnamon-Buff; entire dorsum with uniform suffusion of brown hairs; circumorbital areas Pale Pinkish Buff, strongly suffused with black hairs; postauricular patches Pale Pinkish Buff; circumoral area, dorsal surfaces of fore and hind feet and legs, and entire underparts white; upper arms with indistinct buffy patch; fore and hind feet each with five digits bearing claws; palmar and plantar surfaces of feet entirely naked, the latter with six metatarsal tubercles; vibrissae relatively long with equal numbers of white and brown hairs; pinnae of ears sparsely haired Ochraceous-Buff basally and Hair Brown distally; tail relatively long and indistinctly bicolored, being somewhat darker dorsally with greater suffusion of brown hairs and with inconspicuous Drab pencil. Skull: Large and robust; zygomata heavy; braincase flattened; auditory bullae large; supraorbital ridges poorly defined; nasals long; and rostrum wide. Comparisons. From topotypes of Gerbillus campestris dodsoni from Ain Hammam, Tripolitania Province, Libya, and representatives of G. c. dodsoni from Tazerbo Oasis, Cyrenaica Province, specimens from Bahr el Tubat are paler and more uniform in dorsal color; have longer, less bicolored, and less tufted tails; proportionately smaller and less inflated auditory bullae; and are larger in all measurements. Compared to topotypes of Gerbillus campestris haymani from Siwa Oasis, Egypt, specimens from Bahr el Tubat, Cyrenaica Province, have slightly longer tails, smaller ears, slightly shorter molariform teeth, and narrower zygomatic arches. These subtle differences, how- ever, fall well within the range of variation for members of G. c. haymani, and because these specimens from Bahr el Tubat are much larger cranially and in body size from all other contiguous subspecies, they are clearly referable to G. c. haymani. For comparisons with G. c. brunnescens, G. c. patrizii, and G. ec. wassifi, see accounts of those subspecies. Remarks. Hayman (1949), somewhat dubiously, referred specimens from Siwa Oasis in western Egypt to Dipodillus dodsoni but recognized that these specimens differed from typical representatives of Dipodillus dodsoni from Tripolitania Province in having slightly paler and less rufous tails with slaty rather than brownish pencils. Ellerman and Morrison-Scott (1951) assigned these same specimens to Gerbillus campestris campestris and suggested that D. dodsoni was probably a synonym of G. c. campestris and thus extended the range of the nominate subspecies to include most of coastal and interior Libya and RODENTS OF LIBYA 141 a portion of western Egypt. Later, Wassif (1956) recognized that these gerbils from Siwa Oasis were distinct from those of the Mediterranean littoral and assigned the coastal population to G. c. campestris and those of the interior to G. c. dodsoni. Setzer (1958) concluded that the gerbils from Siwa Oasis and those from the coastal areas were distinct from each other and from both G. c. dodsoni and G. c. campestris; accordingly, as new subspecies, he described the interior population as G. c. haymani and the coastal population as G. c. wassifi. It is now known that G. c. haymani represents a subspecies which can be distinguished from all other subspecies of Gerbillus campestris by its larger size, and its range is limited to the low-lying, sandy depressions surrounding Bahr el Tubat and Siwa Oasis. When speci- mens become available from Giarabub Oasis in Cyrenaica Province, Libya, and the Qattara Depression of Egypt, they probably also will be referable to G. c. haymani. This small series was taken in the midst of an extensive growth of Phragmites adjacent to the large saline lake of Bahr el Tubat. The substrate in this habitat was hard, impervious, sandy clay which was furrowed with cracks and crevices and covered with encrustations of whitish salts. Gerbillus campestris patrizii (de Beaux) Dipodillus dodsoni patrizii de Beaux, Ann. Mus. Civ. Stor. Nat. Genova, vol. 55, pp. 379-381, 1932 (El Giof, Cufra Oasis, Cyrenaica Province, Libya). SPECIMENS EXAMINED. Thirty-two, from Cyrenaica: El] Hauuari, Cufra Oasis, 15; El Giof, Cufra Oasis, 17. MEASUREMENTS. Averages and extremes of 10 adult males and 7 adult females from the type locality are, respectively: Total length 211.8 (183-233), 213 (192-225); length of tail 118.4 (97-131), 121.7 (110-127); length of hind foot 26 (23-28), 26.1 (24-27); length of ear 15.9 (15-18), 15.7 (14-17) ; occipitonasal length of skull 29 (27.6-30.3), 28.6 (26.1-28.8); length of auditory bulla 9.3 (8.5-10), 9.3 (8.4-9.5) ; crown length of upper molariform toothrow 3.8 (3.4—-4), 3.8 (3.3-4) ; greatest breadth across zygomatic arches 15.2 (14.3-15.8), 15.2 (14-16.2) ; least interorbital breadth 5.2 (4.8—-5.4), 5.2 (5-5.6); breadth of rostrum at level of antorbital foramina 3.1 (2.8-3.3), 3.1 (2.8-3.3) ; length of nasals 11.2 (10.5-11.7), 10.9 (9.7-11.4). Diacnosis. Representatives of this subspecies are extremely variable in dorsal coloration ranging from Ochraceous-Tawny through Avellaneous, Cinnamon, and Tawny-Olive. Nearly all specimens have strong suffusions of dark colors on the middorsal region and rump, which impart a streaked appearance to the entire dorsum. This variegated dorsal color is perhaps the most diagnostic and unifying character of this subspecies. Other characteristics of this subspecies are as follows: Postauricular patches indistinct and suffused with buff; 142 U.S. NATIONAL MUSEUM BULLETIN 275 eye ring black; mystacial, rostral, and scapular areas Light Buff; vibrissae relatively long with a preponderance of black hairs; ears relatively long and pinnae sparsely haired, Antimony Yellow basally and Saccardo’s Umber distally, with small tuft of buffy hairs on anterior margin; dorsal surfaces of forelegs, hindlegs, and feet white; ventral surfaces of hindlegs with strong suffusions of plumbeous- colored hairs; palmar and plantar surfaces of feet entirely naked, the latter with six distinct metatarsal tubercles; fore and hind feet each with five digits bearing claws; tail relatively short, distinctly bicolored in most specimens, ranging from tan to dark brown dorsally and from a medium buff to almost white ventrally (in some darkly colored specimens, the tail is almost uniformly colored throughout); tail markedly penicillate colored. Avellaneous to dark brown on distal one-third; basal portions of all dark colored hairs Deep Plumbeous; underparts white with occasional suffusion of buff. Skull: Noticeably small and compact for the species; auditory bullae small, but mod- erately inflated ventrally; zygomata heavy and narrow in breadth; interorbital breadth narrow; braincase, notably the parietals, flattened. Comparisons. Members of this subspecies can be readily dis- tinguished from those representing Gerbillus campestris haymani and Gerbillus campestris wassifi from farther north in Cyrenaica and western Egypt by the markedly smaller size of body and cranium, darker, more variable dorsal color, and more prominently tufted tail. In general characters, these gerbils from Cufra Oasis most clearly resemble those of Gerbillus campestris dodsoni, whose range is to the west and north but differ in their smaller body size, shorter tail, and smaller size of all cranial measurements. For comparison with Gerbillus campestris brunnescens, see account of that subspecies. Remarks. De Beaux (1932, p. 379) described Dipodillus dodsoni patrizi (=Gerbillus campestris patrizii) as a new subspecies separable from Dipodillus dodsoni dodsoni (= Gerbillus campestris dodsont) pri- marily by its smaller size. Setzer (1957) placed G. c. patrizw in syn- onymy under G. c. dodsoni and stated that the characters used by de Beaux in separating patrizii from dodsoni were all typical of sub- adult specimens of the latter. Setzer examined no specimens of typical G. ce. patrizii, however, and apparently based this assignment solely on comparisons with the characters given in the original description. In cranial and external measurements, the large series of adult topo- types collected by the present author agree closely with those given by de Beaux in the original description. In studying these gerbils from Cufra, extreme care was taken to select only fully adult speci- mens. The present study indicates that gerbils from Cufra, primarily RODENTS OF LIBYA 143 because of their diminutive size, warrant reinstatement as a distinct subspecies. Within series of these gerbils, all gradations of body size are noted, ranging in length from 230 mm to well below 200 mm. This wide range may reflect degenerative changes in the genotype of the popu- lation engendered by the agency of ‘‘drift’”’ resulting from a long period of absolute physical isolation without any outbreeding with marginal populations. Specimens from nearby Bzema and Tazerbo Oases, although similar in color to those from Cufra, are clearly re- ferable in their larger size and cranial characters to G. c. dodsoni and show no evidences of gene exchange with G. c. patriziv. An adult male, 325348, from El Hauuari, is uniformly gray and lacks the typical variegated character of the dorsal pelage. This specimen probably represents an aberration in color without any genetic significance. EcoLoGIcaL OBSERVATIONS. The series from both E] Hauuari and El Giof were collected among sedges and other mesophytic plants that occur as a fringe of dark green vegetation surrounding the low-lying saline lakes in the interior of these oases. In most areas, these sedges form almost impenetrable masses; consequently, trapping is usually limited to the periphery of the habitat. In these areas the substrate is extremely hard and impregnated with salts from adjoining lakes. These gerbils were never taken from the sandy areas of the oases proper. In these areas, Gerbillus gerbillus and Acomys cahirinus are the dominant rodents. Gerbillus campestris wassifi Setzer Gerbillus campestris wassifi Setzer, Journ. Egypt. Publ. Health Assoc., vol. 33 no. 6, pp. 209-211, 1958 (Libyan Plateau, near Salum, +200 ft., Western Desert Governorate, Egypt). SPECIMENS EXAMINED. Five (1 skin only), from 5 km W Bardia, Cyrenaica Province, Libya. MEASUREMENTS. Measurements of an adult male, 325509, from the above locality are: Total length 245; length of tail 135; length of hind foot 30; length of ear 17; occipitonasal length of skull 30.4; length of auditory bulla 9.3; crown length of upper molariform tooth- row 4.1; greatest breadth across zygomatic arches 16; least inter- orbital breadth 5.5; breadth of rostrum at level of antorbital foramina 3.2; length of nasals 12. Diagnosis. Dorsum Ochraceous-Tawny becoming lighter on sides and rostral areas, all parts with strong suffusions of darker hairs; pre- and postauricular spots and supraorbital patches conspicuous and white with faint admixture of buffy hairs; pectoral areas with indis- tinct buffy patch; eye ring black; circumoral areas, dorsal surfaces of forelegs, hindilegs, feet, and entire underparts white; ventral surface 144 U.S. NATIONAL MUSEUM BULLETIN 275 of hindlegs and thighs with conspicuous plumbeous-colored patches, fore and hind feet naked ventrally, each with five digits with claws; vibrissae relatively long and formed of equal numbers of light and dark hairs; ears long, sparsely haired, Ochraceous-Buff basally and Brown- ish Olive distally and with distinct tuft of buffy hairs on anteroventral margin; tail prominently bicolored, dorsally same color as dorsum, but with stronger suffusions of brown hairs, ventrally almost white; tail with indistinct pencil; immature specimens of this subspecies markedly paler and more uniform in dorsal color, approaching Cinnamon-Buff, and lacking the strong suffusions of dark hairs. Skull: Large and robust; molariform teeth large; auditory bullae moderately inflated; anterior palatine foramina wide; zygomatic breadth wide; nasals long and posterior palatine canals wide and conspicuous. Comparisons. From topotypes of Gerbillus campestris haymani from Siwa Oasis, Western Desert Governorate, Egypt, this specimen from Bardia differs in darker dorsal color with stronger suffusion of brown, markedly shorter and more prominently bicolored tail with a much reduced terminal brush, smaller auditory bullae, and smaller size of all other cranial details, being of comparable size only in the crown length of the molariform toothrow. Compared to topotypes of Gerbillus campestris dodsoni from Ain Hammam, Tripolitania Province, Libya, this specimen from Bardia is paler and more uniform in dorsal color, has markedly smaller auditory bullae, wider interorbital breadth and rostrum, and less conspicuously tufted tail. For comparisons with Gerbillus campestris brunnescens and Ger- billus campestris patrizii, see accounts of those subspecies. Remarks. This specimen from Bardia differs from typical G. c. wassift from Salum, Egypt, in having larger hind feet, a less promi- nently tufted tail, more grayish hairs on the head, slightly smaller auditory bullae, and slightly narrower anterior palatine foramina. In view of the geographic proximity of Bardia to the type locality of wassifi in Egypt and the continuity of habitat between them, even these subtle differences would not be expected. Thus, this single speci- men may not possess characters typical of the whole population. These differences do not depart markedly from those considered typical for G. c. wassifi, and specimens from Libya are included with this subspecies. In reviewing the dipodils of Egypt, Wassif (1956) assigned speci- mens from coastal Egypt to Gerbillus campestris campestris; the type locality of which is far to the west at Philippeville in the Province of Constantine on the Algerian Coast. He had no specimens of typical G. c. dodsoni but referred gerbils from Siwa Oasis, Egypt, to this subspecies. RODENTS OF LIBYA 145 He stated further that these coastal gerbils differed from those of the interior in their smaller size, denser fur, less tufted tails, and less variable dorsal pelage. Later, Setzer (1958) also recognized these differences and named Gerbillus campestris wassifi, with a range ascribed to northwestern coastal Egypt, and described Gerbillus campestris haymani representing the interior populations of Siwa Oasis. He concluded that by virtue of its smaller size and prominently biocolored tail, G. c. wassifi was more closely related to G. c. dodsoni than to G. c. haymani and attributed these similarities to the con- tinuity of suitable habitat between the ranges of G. c. dodsona and G. c. wassift. At that time, however, the range of G. c. dodsoni was thought to include northern Cyrenaica and thus to be contiguous with that of G. c. wassifi. Northern Cyrenaica is now included within the range of a new subspecies, G. c. brunnescens, and it probably was to representatives of this subspecies, then known as G. c. dodsoni, that Setzer (1958) alluded in discussing the affinities of G. c. wassifi. It is now known that G. c. wassifi is more closely related to G. c. brunnescens than to either G. c. dodsoni or G. c. haymani. The range of G. c. campestris is thought to be confined to coastal Algeria and Tunisia and possibly northwestern Libya. In Libya, the range of this subspecies is confined to the Mediter- ranean littoral of northeastern Cyrenaica at least as far west as Derna, where intergradation with G. c. brunnescens occurs. The specimens from Bardia were collected among some localized concentrations of thorny, bushy perennials growing from residual mounds or elevations in the bottom of a recently flooded and denuded wadi. 14 15 16 17 18 19 Ficure 27.—Statistical comparison of length of ear of the subspecies of Gerbillus campestris: A, G. c. brunnescens; B, G. c. dodsoni; C, G. c. patrizit. 146 U.S. NATIONAL MUSEUM BULLETIN 275 Figure 28.—Statistical comparison of length of auditory bulla of the subspecies of Gerbillus campestris. Notation remains the same as in figure 27. Gerbillus grobbeni Klaptocz Gerbillus (Dipodillus) grobbent Klaptocz, Zool. Jahrb. Syst., vol. 27, p. 252, 1909 (Derna, Cyrenaica, Libya). Remarks. No specimens of this gerbil were obtained in the present study. Judging from measurements given in the original description, this species most likely represents Gerbillus amoenus. Zavattari (1934) reported G. grobbeni from Libya, but mentioned no specimens other than those from the type locality. Later, Ellerman and Morrison-Scott (1951) suggested that G@. grobbeni probably represented Gerbillus nanus Blanford. Toschi (1954) referred specimens from Derna and the Wadi el Kuf to G. grobbeni but considered the latter as a subspecies of Gerbillus dasyurus (Wagner). Setzer (1957) tried unsuccessfully to obtain topotypes of this species but made no comments regarding its probable status. In the present work, gerbils representing the subgenus Dipodillus were obtained from both the type locality at Derna and from the Wadi el Kuf. These gerbils clearly represent Gerbillus campestris and Gerbillus kaiser, neither of which approach very closely the measure- ments and description of G. grobbeni as given by Klaptocz in the original description. This species is considered to be of doubtful validity but is being retained until such time as specimens are available to establish its true status. RODENTS OF LIBYA 147 Gerbillus henleyi henleyi (de Winton) Dipodillus henleyz de Winton, Nov. Zool., vol. 10, p. 284, August 1903 (Zaghig, Wadi Natroun, Egypt). GENERAL DISTRIBUTION OF SPECIES. Egypt, Sinai, Libya, and Algeria; range probably also includes Tunisia. DisTRIBUTION IN LisyA. Coastal plain and littoral deserts of northern Cyrenaica and the Gulf of Sirte. SPECIMENS EXAMINED. Six, from Cyrenaica: 11 km E Ain el Gazala, 2; 20 km E Tobruch, 3 (1 skin only); 65 km WNW EI Agheila, 1. Li oh BEY: A p_¢_e KILOMETERS Gerbillus henleyi henley Ficure 29.—Distribution of Gerbillus henleyt henleyt. MEASUREMENTS. Measurements of two adult males, 325540 and 325549, from 20 kilometers east of Tobruch, are: Total length 161, 162; length of tail 90, 94; length of hind foot 18, 19; length of ear 10, 10; occipitonasal length of skull 22, 21.9; length of auditory bulla 8.7, 8.7; crown length of upper molariform toothrow 2.8, 2.7; greatest breadth across zygomatic arches 12, 12; least interorbital breadth 4.3, 4.2; breadth of rostrum at level of antorbital foramina 2.4, 2.3; length of nasals 7.6, 7.6. 148 U.S. NATIONAL MUSEUM BULLETIN 275 Dracnosis. Diminutive in size; pelage short and silky; upperparts Buckthorn Brown, uniformly suffused with darker hairs and becoming paler on sides and flanks; postauricular and supraorbital patches distinct and white; subauricular areas with strong admixture of black hairs; circumoral areas, portions of the cheeks, dorsal surfaces of forelegs, hindlegs, feet, and entire underparts pure white; vibrissae delicate and formed from both light and dark colored individual hairs; fore and hind feet extremely small, naked ventrally and each bearing five digits with claws; tail Pinkish Buff, relatively long and with faint terminal tuft, and appearing bicolored owing to moderate suffusions of dark brown hairs dorsally; pinnae of ears extremely short and sparsely haired; outer surfaces of pinnae approaching color of dorsum; internal surfaces somewhat bicolored, becoming darker distally and approaching Light Drab. Skull: Small and gracile; rostrum relatively short; zygomata fragile; molariform teeth small and diverging slightly anteriorly; braincase markedly expanded and appearing almost bul- bous; auditory bullae noticeably large and markedly inflated ventrally ; basioccipital triangular-shaped posteriorly and projecting anteriorly between auditory bullae as a narrow rod; posterior lacerated foramina large and distinct. Comparisons. Compared to a topotype of Gerbillus henleyi makrami Setzer from Bir Kansisrob, Sudan Government Administrative Area, Egypt, these specimens from Libya are larger in all respects and have more prominently domed braincases. From topotypical Gerbillus henleyi mariae (Bonhote) from the vicinity of Cairo, Egypt, these gerbils from Libya differ in having slightly shorter skulls, smaller and less inflated auditory bullae, wider inter- orbital breadths and rostra, shorter nasals, wider basioccipitals ante- riorly, and smaller size of all external measurements except length of ears. In color, G. h. mariae is noticeably darker with a greater suffusion of grayish tones. These specimens from Libya are almost indistinguishable from topotypes of G. h. henleyi from coastal Egypt but differ in slightly larger size of body, interorbital breadth and width of rostrum, and smaller occipitonasal length of skull. In overall size of body and occipi- tonasal length they are nearer to G. h. mariae, but because they share more characters with the nominate subspecies and have a range con- tiguous with populations of the latter in western Egypt, they are here referred to G. h. henleyi. Remarks. The diminutive size of members of this species serves to distinguish them from all other gerbils in Libya. Until as recently as 1955, this distinctive species was unknown from Libya. Earlier col- lectors in Libya tended to concentrate their efforts in the interior oases and consequently neglected the coastal areas to which these RODENTS OF LIBYA 149 gerbils are largely confined. Even today the species is poorly known and is represented by comparatively few specimens from widely scattered localities. Wassif (1956) assigned specimens from western coastal Egypt to Gerbillus henleyi jordani (Thomas), whose range is far to the west in the Central Plateau of Algeria. He had no specimens of G. h. jordani and based this assignment on similarities in size, particularly in the length of the auditory bullae. Later, Setzer (1958) referred all Egyptian specimens from west of the Nile River to G. h. henley and asserted that G. h. jordani did not occur in Egypt. The inclusion of the Libyan specimens within G. h. henleyi extends the range of the nominate subspecies even farther westward and indicates that G. h. jordani is not a part of the Libyan fauna. In the original description of Dipodillus jordani (= Gerbillus henleyr jordant), Thomas (1918) distinguished it from Dipodillus henleyr (=Gerbillus henleyi henleyi) on the basis of the larger size of the former. This larger size of G. h. jgordani was further indicated by Setzer, who compared members of the two subspecies at the British Museum. Measurements made by the author on specimens from Libya and of topotypical specimens of G. h. henleyi from coastal Egypt are larger, rather than smaller as would be expected, than those of the type specimen of G. h. jordani. For the present, until much larger series of these gerbils become available from Algeria and western Libya to provide more reliable comparative material, I prefer to regard G@. h. jordani as a subspecies of uncertain status confined to the Central Plateau of Algeria. EcoLoGICAL OBSERVATIONS. These small gerbils are apparently confined to the coastal plain and littoral deserts of northern Libya. Two specimens were obtained from near Ain el Gazala along the coastal highway where a series of large, exposed hummocks supported sparse growths of thorny perennials. These hummocks were riddled with larger burrows, presumably those of jirds (Meriones), as two of the latter were taken in the same trapline. Near Tobruch, three specimens were obtained from the broad coastal plain. At this locality, the plant cover was almost complete and continued uninterruptedly for several kilometers. According to Setzer (1957), the habitat near El Agheila is characterized by a “pebbly desert which is slightly raised above the coastal plain.” Gerbillus kaiseri Setzer Gerbillus kaiseri Setzer, Journ. Egypt. Public Health Assoc., vol. 33, no. 6, pp. 214-216, 1958 (Mersa Matruh, Western Desert Governorate, Egypt). GENERAL DISTRIBUTION OF SPECIES. Coastal areas of Libya and Egypt as far east as the Nile River; range probably also includes portions of Tunisia and Algeria. 150 U.S. NATIONAL MUSEUM BULLETIN 275 DisTRIBUTION IN LiByA. Coastal plain and littoral deserts of Cyrenaica and the uplands of the Gebel Nefusa and Gebel Tigrinna in Tripolitania. SPECIMENS EXAMINED. Twenty, from Cyrenaica: 3 km E Derna, 2; 2 km N Coefia, 6; 8 km N Benghazi, 2; 20 km E Tobruch, 5; from TRIPOLITANIA: 20 km E Rumia, 1; 12 km S Chicla, 4. MEASUREMENTS. Measurements of one adult male, 325028, and two adult females, 325027 and 325550, from 20 kilometers east of Tobruch, Cyrenaica Province, are, respectively: Total length 164, 169, 159; length of tail 83, 81, 77; length of hind foot 21, 21, 20; length of ear 12, 12, 12; occipitonasal length of skull 25.8, 26.3, 24.4; length of auditory bulla 8.4, 8.6, 8.1; crown length of upper molariform toothrow 3.5, 3.8, 3.5; greatest breadth across zygomatic arches 14.2, 14.2, 13.5; least interorbital breadth 5.1, 4.7, 4.6; breadth of rostrum at level of antorbital foramina 2.7, 2.6, 2.6; length of nasals 9.6, 9.7, 9.4. Diaenosis. Color of the dorsum varying widely according to geographic locality and ranging from Light Ochraceous-Buff, Cin- namon-Buff, or Tawny Olive to Sayal Brown; complete dorsum L I oBOy A tin jet Gerbillus kaiseri Ficure 30.—Distribution of Gerbillus katsert. RODENTS OF LIBYA 151 interspersed with numerous brown-tipped hairs which render a variegated or particolored aspect to the pelage; in most specimens Plumbeous underfur exposed dorsally; region surrounding eyes heavily suffused with black and gray, in some specimens extending into subauricular area as a distinct patch; postauricular patches white and somewhat limited in size; rostral area Cinnamon-Buff; vibrissae relatively short, hairs having origin near the eye black whereas those arising nearer the tip of the rostrum white; pinnae of ears short, sparsely haired, Ochraceous-Buff basally and Hair Brown distally and with prominent tufts of silky, buffy hairs arising from the anterior margins; circumoral areas, pectoral region, dorsal sur- faces of forelegs, hindlegs, feet, and entire underparts white; fore and hind feet naked ventrally and each bearing five digits with claws; tail noticeably short, unicolorous, except for suffusions of brown hairs dorsally, and somewhat paler in color than that of the dorsum; a pencil or terminal tuft is lacking. Skull: Small; anterior palatine foramina long and wide; posterior palatine canals distinct and rel- atively wide; auditory bullae small and slightly inflated ventrally; basioccipital present as a rather broad triangular plate between the auditory bullae and forming an elongated foramen on its lateral margins; zygomata relatively fragile; braincase moderately domed; in very old adults a distinct longitudinal fossa present on the medial surface of the frontals extending forward to the level of the infra- orbital foramina. Comparisons. Specimens from Libya somewhat resemble a spec- imen (MNHN, no. 1789) of Gerbillus simoni Lataste from Guelt es Stel, Algeria, but differ in noticeably longer tails, less robust skulls, much more fragile zygomata, and paler, shorter, less lustrous fur. Unfortunately, the auditory bullae, which are reputedly of taxonomic significance in distinguishing G. simoni from G. kaiseri, are badly broken in this specimen of G. simoni from Algeria, and comparisons based on this character are not possible. Members of this species can be readily distinguished from all other dipodils in Libya by their markedly shorter and almost unicolorous tails and the absence of a well-defined terminal tuft. Remarks. Wassif (1956) assigned specimens from coastal Egypt to Gerbillus simoni. This assignment was based on resemblances to the measurements and descriptions of G. simoni as given by Lataste (1881). Prior to this time, no specimens of G. simoni were known from outside Algeria. Earlier, Ellerman (1941) included G@. simoni and G. henleyi within the G. simoni group but stated that G. simon could readily be distinguished from G. henleyi and all other members of the group by its smaller auditory bullae. Later Ellerman (1949) and Ellerman and Morrison-Scott (1951) considered G. simoni as a sub- 152 U.S. NATIONAL MUSEUM BULLETIN 275 species of Gerbillus dasyurus (Wagner). The latter assignment has no morphological or taxonomic justification, as the two forms have nothing in common to suggest conspecificity. Setzer (1958), although recognizing that these gerbils from Egypt and those from Algeria were related, considered the Egyptian specimens to represent a new species, G. kaiseri, distinguished from G. simoni primarily by its significantly longer tail. He did not compare the crania of the two species but in- ferred that those of G. kaiseri would be larger and suspected those of G. simoni to be about the same size as those of G. henleyi. Judging from the single specimen of G. simoni from Guelt es Stel, Algeria, the two species are somewhat comparable in cranial size, but G. simoni appears to be more robust, particularly in having heavier and more massive zygomatic arches. Compared to G. henleyi, both G. kaiseri and G. simoni are markedly larger cranially, have much shorter and more unicolorous tails, proportionately smaller auditory bullae, larger ears, and larger size of body. The present series from Cyrenaica and Tripolitania constitutes the first record of occurrence of G. kaisert in Libya. Gerbils from the Cyrenaican coast differ from topotypes and near topotypes of G. kaiseri from Egypt in their slightly darker dorsal color and shorter tails, but in all other characters the two populations are almost indistinguishable. Specimens from the Gebel Nefusa in Tripolitania, although geographically closer to the type locality of G. stmoni in Algeria, possess all characters typical of G. kaiser? and show no evi- dences of interbreeding with G@. simoni. It is now clear that G. katser and G. simoni represent two distinct species with separate ranges ascribed to each. The range of the former includes the littoral areas and coastal escarpments of Libya and Egypt, and G. simoni is con- fined to the high plateaus of the Algerian Atlas. Within Libya the various discontinuous populations are remarkably uniform in color and cranial characters. Specimens from Derna, how- ever, are slightly darker than those from elsewhere in Cyrenaica, and four specimens from Tripolitania have smoother, more sparsely haired tails than any of the other populations of this gerbil in Libya. Adequate series are still lacking and a more thorough analysis of the differentiation among the various populations will have to be deferred until a later date. It is doubtful that populations distributed over such a wide geographic area represent the same subspecies. EcoLoGIcaL OBSERVATIONS. In Cyrenaica these gerbils are confined to the relatively narrow coastal plain and adjacent lowlands. Appar- ently they prefer habitats lacking sand. Traplines set throughout coastal dunes failed to take any of these gerbils. Farther west in Tripolitania four specimens were collected from the highest portions of the Gebel Nefusa in the upper reaches of narrow, grassy valleys RODENTS OF LIBYA 153 that eventually drain through the escarpment into the coastal plain. In these high, windy valleys vegetation is rather abundant and consists largely of grasses and other herbs. These gerbils were never collected in large series and were usually taken less frequently in traps than other species. Other species of rodents occurring sympatrically with this species include Gerbillus campestris, Gerbillus eatoni, Gerbillus henleyi, Gerbillus aureus, Ger- billus amoenus, and Jaculus orientalis. The sporadic distribution of these gerbils in coastal Libya is un- accountable, as suitable habitats are present throughout virtually all of coastal Libya. This species is unknown from the coastal areas of Tripolitania and the coastal plain of the Gulf of Sirte; however, more extensive col- lecting in these areas will probably reveal its presence. Genus Pachyuromys Lataste Pachyuromys duprasi natronensis de Winton Pachyuromys dupresi (sic) natronensis de Winton, Nov. Zool. vol. 10, p. 285, 1903 (Bir Victoria, on way to Wadi Natroun from the Nile, Egypt). GENERAL DISTRIBUTION OF spEcI&s. North Africa, including Egypt, Libya, Tunisia and Algeria, and southward into Mauritania. DisTRIBUTION IN LispyA. Hamadas of Tripolitania, Cyrenaica, and the northern Fezzan, and interior portions of the coastal plain of the Gulf of Sirte in Cyrenaica and Tripolitania. SPECIMENS EXAMINED. Twenty-four, from Cyrenaica: 65 km WNW E] Agheila, 1; Wadi er Rueis, 340 km WNW Tazerbo Oasis, 1; from TRIPOLITANIA: 20 km E Rumia, 9;3 km W Rumia, 2; 12 km S Chicla, 5; 7 km S El] Gheddahia, 1; 5 km E Sirte, 2; 55 km SW Bir Allagh, 1;15 km WNW Marble Arch, 1; 5 km E Derg, 1. PUBLISHED RECORDS IN Lispya. Cyrenaica: El] Agheila (de Beaux, 1932); Zauia Mechili (de Beaux, 1938); Frezzan: Bir el Fatia (Toschi, 1951). MEASUREMENTS. Averages and extremes of six adult males and the measurements of two adult females from 20 kilometers east of Rumia, Tripolitania, are, respectively: Total length 165.5 (158-175), 155, 153; length of tail 55 (51-58), 51, 52; length of hind foot 23.5 (23-24), 22, 22; length of ear 17.2 (17-18), 15, 15; condylobasal length of skull 31.5 (30.8-32.1), 29.8, 29.7; greatest length of skull 37.7 (36.6— 39.2), 35.8, 34.8; greatest breadth across auditory bullae 21.7 (21.2—- 22.3), 20.5, ?; crown length of upper molariform toothrow 4.9 (4.6-5), 4.7, 4.7; least interorbital breadth 6.1 (5.9-6.3), 6, 6.1; greatest length of nasals 12.9 (12.3-14), 11.9, 11.7; length of auditory bulla 18 (17.4— 18.7), 16.9, 16.9; depth of auditory bulla 14.2 (13.8-14.5), 13.5, 12.8; greatest breadth across zygomatic arches 19.3 (18.7-19.9), 17.9, 18.5. 285-134 O—68——11 154 U.S. NATIONAL MUSEUM BULLETIN 275 4 TT L oe A | KILOMETERS \ a Pachyuromys duprasi natronensis Ficure 31.—Distribution of Pachyuromys duprasi natronensis. DiaGnosis. Body noticeably compact and almost wedge-shaped in outline; pelage of dorsum long, silky and lustrous, ranging in color from Cinnamon-Buff to light Pinkish Cinnamon, a few more brilliantly colored specimens approaching orangish-buff; all parts of dorsum with medium to strong suffusions of brown and black hairs, being particu- larly concentrated on the rump; pelage of sides and scapular areas paler in color than the dorsum and less uniformly suffused with darker hairs; postauricular patches indistinct or absent; ears sparsely haired, about same color as the dorsum, and with prominent tufts of Cinnamon-Buff hairs on anteroventral margins; eye rings dark brown; area between eye and base of the ear strongly suffused with dark brown hairs and in some specimens, present as a distinct dark band extending from the eye to the ear; vibrissae soft, silky, and composed of both light and dark hairs; palmar and plantar surfaces sparsely haired, the latter with bare area in region of calcaneus; fore and hind feet each with five digits bearing pale colored claws; circumoral areas, chin, dorsal surfaces of forelegs, hindlegs, feet, and entire underparts pure white; tail extremely short, markedly enlarged in girth owing to its function as a storage depot for fat, approaching RODENTS OF LIBYA 155 same color as the pelage of the dorsum, but with faint suffusions of whitish hairs on ventral surface. Skull: Medium in size; flattened dorsoventrally and wedge-shaped; parietal ridges poorly defined; suprameatal triangles large and usually completely enclosed by enveloping processes of the supraoccipital and temporal bones; auditory bullae conspicuously enlarged and inflated ventrally; audital portions of bullae extending posterior to mastoidal processes and covering almost one-half of ventral surface of skull; meatal processes markedly enlarged and projecting farther laterally than the squamous portions of the temporal bones to which they are firmly adpressed ; mastoidal portions of bullae also markedly enlarged and bulbous, and projecting conspicuously beyond the level of the occiput; pterygoid processes relatively short; hamulae firmly applied to anterior surface of the auditory bullae; anterior palatine foramina and _ posterior palatine canals markedly enlarged and bowing laterally; zygomata relatively delicate and slightly convergent anteriorly; lachrymals relatively small. Comparisons. This species resembles Meriones libycus but can easily be distinguished from it and from all other jirds by its markedly shorter and heavier tail, larger auditory bullae, and more wedge- shaped body. From a near topotype of Pachyuromys duprasi duprasi Lataste from Ghardaia, Algeria, specimens from 20 kilometers east of Rumia, Tripolitania, and those from various localities around the Gulf of Sirte, differ in having more gracile and less robust skulls (particularly more delicate zygomata), markedly larger posterior palatine canals, and longer and narrower rostra. Most of the Libyan specimens are also darker in dorsal color and smaller in external and cranial dimensions, being of comparable or larger size in length of ears, crown length of upper molariform toothrows, length of nasals, and length of auditory bullae. A single specimen (skin only, BM, no. 39.2168) of Pachyuromys duprasi faroulti Thomas from Mecheria, western Algeria, is markedly darker in dorsal color than the Libyan specimens and has silkier, more lustrous pelage. Cranial comparisons are not possible at this time, but presumably P. d. faroulti differs significantly from Libyan specimens, as the range of the latter is confined to the High Plateau of northern Algeria and is, geographically, far removed from the Libyan populations. Remarks. Although the specimens from near Rumia, Tripolitania, are Clearly referable to Pachyuromys duprasi natronensis, they differ from topotypes of the latter from Bir Victoria, Western Desert Governorate, Egypt, in being larger in condylobasal length of skull, and in having slightly larger auditory bullae, slightly wider zygomata, 156 U.S. NATIONAL MUSEUM BULLETIN 275 and longer ears. These specimens from Rumia are also darker in dorsal color, including the tail, and have a more marbled appearance dorsally, owing to a much stronger suffusion of brownish hairs. Compared to specimens from Rumia, specimen, 321831, from 5 kilometers east of Derg and another specimen, 321832, from 55 kilo- meters SW of Bir Allagh, Tripolitania, have a more streaked pelage, and the dorsal lip of the external auditory meatus is more inflated and more closely applied to the squamous portion of the temporal. In the above characters, these two specimens resemble P. d. duprasi of Algeria, but in all other characters, they are closer to P. d. natronensis. Toschi (1951) referred a specimen from Bir el Fatia, Fezzan Province, to P. d. duprasi. He apparently based this assignment largely on geographic grounds, as the measurements of this specimen are much closer to those of topotypes of P. d. natronensis. Specimens from the coastal plain of the Gulf of Sirte in Tripolitania are the palest in dorsal color and have the smallest hind feet of all representatives of this species in Libya. In view of the rather wide range of this species in Libya, specimens from the various localities are remarkably uniform morphologically. These similarities suggest a relatively constant genetic interchange among the various populations rendered possible by the continuity of suitable habitat throughout most of coastal Libya. With the exception of two specimens, 321831 and 321832, from western Tripolitania, a single specimen from Bir el Fatia in the Fezzan (Toschi, 1951), and a specimen, 325582, from the Gebel el Harug el Asued of central Cyrenaica, this species in Libya is almost exclusively restricted to localities near the coast. The comparatively few specimens available at the present time cannot serve as a reliable index to their distribution in Libya, and their range doubtless includes a much greater portion of the interior than presently is supposed. A single adult male specimen, 325582, from the Wadi er Rueis, Gebel el Harug el Asued, central Cyrenaica, is the southernmost record for this species in Libya, and it differs strikingly from all other rep- resentatives of this species in Libya by much paler dorsal color and markedly smaller size of all measurements. Unfortunately, the pelage of this specimen is badly worn, and the skull is badly broken rendering certain cranial measurements unavailable. If this specimen is typical of those comprising the population in this region of Cyrenaica, it clearly represents a new subspecies. The jerboas (Jaculus deserti vastus) of this isolated region have also undergone significant changes in size and cranial dimensions. A moderate amount of morphological divergence is not uncommon among populations of geographic isolates. EcoLoGiIcAL OBSERVATIONS. The range of fat-tailed sand rats, in Libya, closely corresponds to that of several other species of rodents, RODENTS OF LIBYA 157 particularly Meriones libycus, Gerbillus eatoni, and Psammomys obesus. These unusual rats are most abundant in the transitional deserts which run roughly parallel to the more lush coastal plain. They seem to prefer the flat, rock-strewn surfaces of the hamadas and the margins of the shallow, dry watercourses which dissect them. In these areas, the surface is covered with coarse pebbles and occasionally with larger boulders, and the vegetative cover is usually sparse and localized. The collecting localities near Rumia and Chicla in Tri- politania are located on the broad uplands near the brink of the coastal escarpment where vegetative cover is denser, and the ground is rockier with occasional outcroppings of larger rocks. Setzer (1957, p. 60) reported the habitat near El Agheila as con- sisting of a “rock shingle type of desert,’’ and suspected that local, terrestrial snails provided a source of food for fat-tailed sand rats. Genus Meriones Illiger The first records of members of this genus in Libya are those of Thomas (1902, p. 8), who, reporting on specimens obtained by Edward Dodson of the Whitaker Expedition to Tripoli (1901), referred specimens from various localities in Tripolitania and the Fezzan to Meriones shawi (Rozet) and Meriones schousboer (Loche). Thomas noticed ‘characteristic differences” in the size of the auditory bullae but mentioned that the two species were almost indistinguishable in external characters and would probably prove to be “mutually exclusive.’ He considered M. schousboei as the Barbary representative of the Meriones erythrourus (Gray) group, the latter being widely distributed throughout the Middle East and Southwest Asia. Later, Thomas (1919), in an effort to clarify the confusion of names applied to this group, divided the genus into four groups based on the relative size and shape of the auditory bullae and the suprameatal triangle. Members of group ‘‘a’”’ with large auditory bullae and large suprameatal triangles included Meriones pelerinus Thomas, Meriones crassus Sundevall, and Meriones pallidus Bonhote. Group ‘‘b,” con- sisting of animals with large auditory bullae but comparatively small suprameatal triangles, included Meriones ibycus Lichtenstein and M. schousboei. Those possessing both small auditory bullae and triangles ’’ which consisted of Meriones isis Thomas and M. shaw. The last division, group “d,’’ consisted of those types having the smallest auditory bullae and included Meriones syrius Thomas, Meri- ones charon Thomas, Meriones ambrosius Thomas, and Meriones blackleri Thomas, whose ranges were confined to Asia Minor and Southwest Asia. The majority of the above species were described as new at this time. formed group ‘“‘c, 158 U.S. NATIONAL MUSEUM BULLETIN 275 3.0 3.2 3.4 3.6 3.8 40 42 Figure 32.—Statistical comparison of breadth of rostrum of the species of Meriones: A, M. caudatus; B, M. crassus; C, M. libycus. 14 15 16 17 Ficure 33.—Statistical comparison of length of palate of the species of Meriones. Notation remains the same as in figure 32. RODENTS OF LIBYA 159 5 oie ¢ eee L 12 13 14 15 Ficure 34.—Statistical comparison of length of audital portion of auditory bulla of the species of Meriones. Notation remains the same as in figure 32. 100 110 120 130 140 150 Ficure 35.—Statistical comparison of length of head and body of the species of Meriones. Notation remains the same as in figure 32. 160 U.S. NATIONAL MUSEUM BULLETIN 275 13 14 15 Ficure 36.—Statistical comparison of length of nasals of the species of Meriones. Notation remains the same as in figure 32. In Libya, local representatives of groups “a,” M. pallidus tripolius Thomas; “b,”? M. libycus caudatus Thomas; and “‘c,’’ M. shawi were recognized. Meriones pallidus tripolius from the Gebel Limhersuk, Tripolitania, and M. libycus caudatus from Bir Ferdjan (= Fergian) El Hammam (=Ain Hammam) were described as new subspecies in the same paper. In Algeria, Meriones richardi (Loche) represented the ‘“‘shawi”’ eroup north of the Atlas. Populations to the south of the Atlas were referred to Meriones guyoni (Loche) and M. schousboer, which Thomas considered as being ‘“‘doubtfully separable” from libycus. Ellerman (1941) divided the genus Meriones into three subgenera, Parameriones Heptner, Cheliones Thomas, and Meriones, based on the degree of hairiness of the sole of the hind feet. The latter subgenus contained all of the North African species, consisting primarily of M. libycus, M. schousboei, and M. erythrourus. These three species, in addition to M. grandis Cabrera, M. trouessarti Lataste, M. kozlow Satunin, M. longifrons Lataste, M. ismahelis Cheesman and Hinton, M. arimalius Cheesman and Hinton, and M. charon, constituted the “libycus” group. Ellerman (1941) included all of the Libyan jirds RODENTS OF LIBYA 161 in the single species, M. libycus. He considered M. shaw as a synonym of M. 1. ibycus and relegated M. crassus to subspecific status. Meriones erythrourus, whose range included Russia and Southwest Asia, was given specific rank but thought possibly to represent only a subspecies of M. libycus. In a later paper, Ellerman (1947) further divided the genus into two additional subgenera, Sekeetamys Ellerman and Pallasiomys Heptner, based upon both the hairiness of the hind feet and the relative size of the auditory bullae, and placed all the forms with large bullae, including all of the Libyan forms, in the subgenus Pallasiomys. In addition, M. crassus was elevated to specific rank and M. shaur withdrawn from synonymy and established as a subspecies of M. libycus. Thus the Libyan representatives of this genus were treated as two full species, M. libycus and M. crassus. Later in the year Ellerman and Chaworth-Musters in ‘‘A Revision of the Genus Meriones” (1947), because of the sympatry of M. 1. shaun and M. l. caudatus, separated M. shaux specifically from both M. crassus aud M. libycus. The above authors separated M. libycus from the other two species by certain external characters (hind claws dark=libycus; hind claws pale=crassus and shawi), and M. crassus and M. shawi were distinguished by the size of the auditory bullae (large in crassus; small in shawi). In addition to the coloration of the hind claws, the degree of closure of the suprameatal processes was given as a character separating M. crassus and M. libycus. Toschi (1954) also recognized three species of the genus Meriones in the Libyan fauna, M. libycus, M. crassus, and M. shawi, represented by five subspecies, including the nominate subspecies of all three species and M. libycus caudatus and M. 1. confalonierit de Beaux. Setzer (1957), the most recent worker on Libyan mammals, included the same three species in the Libyan fauna but considered M. crassus tripolius distinct from M. ce. crassus and did not recognize M. libycus libycus and M. c. crassus as occurring in Libya. In addition, he de- scribed M. shawi azizi as a new subspecies from the northern Cyrenai- can coast. Later, in reviewing the mammals of Egypt, Setzer (1961) did not consider M. shawi as part of the Egyptian fauna and, further- more, questioned its validity as a species. He was unable to find any specific differences between M. shawi and M. libycus and concluded that the former was probably conspecific with M. libycus farther west in North Africa. The present author also doubts the validity of the species M. shawi. Specimens from coastal Libya, formerly referred to Meriones shaun shawi and Meriones shauwi azizi by Setzer (1957), are now considered to be referable to Meriones libycus and are now known, respectively, as Meriones libycus auratus (new subspecies) and Meriones libycus azizi. 162 U.S. NATIONAL MUSEUM BULLETIN 275 However, certain bushy-tailed forms, previously recognized as Meriones libycus confalonierti de Beaux and Meriones libycus caudatus Thomas, are sympatric with these coastal subspecies of M. libycus. It therefore becomes necessary to separate these populations taxo- nomically. Because the name caudatus is older, it is here raised from subspecific status to full species rank. These populations may now be referred to as Meriones caudatus caudatus and Meriones caudatus confalonern. The jirds of Libya are here considered to be represented by the following three species and seven subspecies, three of which are here described as new: Meriones caudatus amplus; Meriones caudatus cau- datus; Meriones caudatus confalonierii; Meriones caudatus luridus; Meriones crassus tripolius; Meriones libycus auratus; and Meriones libycus azizt. The size and shape of the suprameatal triangle and the amount of closure of the latter by the enveloping processes of the supraoccipital and temporal bones varies among the three species of Meriones and serves to readily separate them. In M. crassus, the suprameatal tri- angles are markedly larger than those of M. caudatus and M. libycus and are open behind rather than completely or partially enclosed by the supraoccipital and temporal bones. The suprameatal triangles are of comparable size in M. caudatus and M. libycus, but in M. caudatus the closure of the suprameatal triangles is complete, whereas in M. libycus it is usually imperfect. Individual genetic variation (nongeographic) is relatively high among populations of jirds in Libya, yet the peculiar physiography has resulted in the formation of several distinct subspecies. Morpho- logical features most frequently associated with geographical dis- tribution include differences in the length of the skull, palate, and nasals, and changes in the shape and size of the audital and mastoidal portions of the auditory bullae. In addition to cranial characters, the size and general form of external features are taxonomically important. Color, although sometimes highly variable within a given population, is frequently useful in differentiating the various subspecies. The subspecies of the several species of Meriones, especially those of M. caudatus, are generally more sharply defined morphologically than those of the various species of Gerbillus. This apparent morpho- logical segregation in Meriones may be misleading, inasmuch as the samples representing the subspecies are much smaller than those available for Gerbillus and may not demonstrate the complete range of variation for any given character. Of the three species of Meriones occurring in Libya, only Meriones caudatus is represented by samples of sufficient size to justify statistical analysis at the infraspecific level. RODENTS OF LIBYA 163 Key to the Jirds (Meriones) of Libya 1. Suprameatal triangle large and not enclosed posteriorly by enveloping processes of temporal and supraoccipital bones; mastoidal portion of auditory bulla conspicuously inflated posteriorly and projecting markedly beyond level of occiput =. =. . . . . .M. crassus Suprameatal tangle Bava el eeraleead oe eae ae enloane processes of temporal and supraoccipital bones; mastoidal portion of auditory bulla not conspicuously inflated eens and projecting only slightly beyond level Of OCCIpUL a a's «= 2 2. External meatal process oe adicony ‘Sulla raasleedly: ndlated ‘and ddnste to squamous portion of temporal bone; suprameatal triangle completely en- closed by enveloping processes of the temporal and supraoccipital bones; tail relatively long and prominently tufted... . . . . . .M. caudatus External meatal process of auditory bulla not markedly inflated and clearly distinct from squamous portion of temporal bone; suprameatal triangle imperfectly enclosed by enveloping processes of the temporal and supra- occipital bones; tail relatively short and without prominent tuft. M. libycus Meriones caudatus Thomas Meriones libycus caudatus Thomas, Ann. Mag. Nat. Hist., ser. 9, vol. 3, p. 267, March 1919 (Tamari-Fergian, Tripolitania, Libya). GENERAL DISTRIBUTION OF SPECIES. Currently known only from Libya, but range probably includes other portions of North Africa and adjacent Southwest Asia. DIsTRIBUTION IN Lipya. Widespread throughout the desert areas of Tripolitania and the Fezzan. In Cyrenaica, this species is known only from the coastal plain and the hamadas surrounding the oasis of Giarabub. DISTRIBUTION OF THE SUBSPECIES IN LiBYA. Meriones caudatus amplus. FrzzAn: Oases of Murzuch, Traghen, Meseguin, E] Gatrun, and intervening wadis and hamadas. Meriones caudatus caudatus. TRIpoLITANIA: Coastal plain and in- terior deserts north of the Hamada de Tinrhert and Gebel es Soda. Meriones caudatus confalonieru. CyrENAICA and TRIPOLITANIA: Coastal plain and littoral deserts adjoining the Gulf of Sirte. Meriones caudatus luridus. Cyrenaica: Coastal areas of northern Cyrenaica and the inland hamadas as far south as Giarabub Oasis. PUBLISHED RECORDS IN LiBya. Cyrenarca: El Agheila (de Beaux [Meriones libycus confalonierii], 1932); El Agheila (Meriones libycus confalonierti), Giarabub (Meriones libycus caudatus) (Toschi, 1951). TripouitaniA: Ain Hammam and Tamari-Faradie (Toschi [Meriones schousboei], 1951). Comparisons. This species differs from Meriones libycus as follows: Tail longer, with more prominent pencil, and black rather than brown; auditory bullae noticeably larger and more inflated ventrally and laterally; lateral meatal process of auditory bulla markedly expanded 164 U.S. NATIONAL MUSEUM BULLETIN 275 LtLeya LE? KILOMETERS Meriones caudatus |. amplus 2. caudatus 3. confalonierii 4. luridus Ficure 37.—Distribution of the subspecies of Mertones caudatus. and applied to squamous part of temporal bone, as opposed to lateral meatal process only slightly expanded and clearly distinct from squamous part of temporal bone in M. hbycus; suprameatal triangle elliptical in shape, rather than spherical, with posterior processes completely closed, as opposed to imperfectly closed in M. libycus. Meriones shaui is regarded as a species of doubtful validity and probably is synonymous with Meriones libycus. Specimens representing M. shaun from Algeria differ from topotypical M. caudatus in the same characters as those used to separate M. libycus and M. caudatus, except that the Algerian specimens have even smaller auditory bullae. For comparison of this species with Meriones crassus, see account of that species. Remarks. Thomas (1919) described Meriones libycus caudatus from Ferdjan (=Bir Fergian), Tripolitania Province, and assigned another specimen from nearby Ain Hammam to this subspecies. He separated M. 1. caudatus from typical M. 1. libyeus, as known from the vicinity of Cairo, Egypt, primarily by its ‘markedly longer and finer tail,” and stated that it occurred between the ranges of the original Meriones libycus of Lower Egypt and Meriones schousboei of Algeria. Later, M. RODENTS OF LIBYA 165 schousboei was treated as a subspecies of Meriones libycus by de Beaux (1932) and Chaworth-Musters and Ellerman (1947) and more recently regarded as a synonym of Meriones libycus libycus by Ellerman and Morrison-Scott (1951). In the present study, more specimens of M. caudatus are available from numerous localities throughout Libya, and the taxonomic position of this jird is better understood. In addition to the bushy character of the tail, as established by Thomas (1919), several cranial characters are apparent (see comparisons above) which clearly establish MM. caudatus as a distinct species from M. libycus of the Western Desert of Egypt. Its specific status is confirmed by its being sympatric with populations of M. libycus from several localities in coastal Libya. The use of the name M. caudatus for this species can only be con- sidered provisional at this time. It appears to be the oldest name available for the Libyan population, but extralimital material (pres- ently assigned to M. libycus) that I have examined from Algeria (Beni Ounif) and Iran (Khurasan, Baluchistan, and Kopet Dag Mountains) indicates that the present species is widespread in dis- tribution and probably occurs over large portions of both North Africa and Southwest Asia. It seems almost certain that older names are available, but until additional material is forthcoming and a thorough revision of Meriones throughout its entire range can be undertaken, the name M. caudatus must serve for the Libyan population. EcoLoGICAL OBSERVATIONS. This species is probably the most abundant and widely distributed large rodent in Libya. These jirds seem to prefer arid habitats and reach their greatest numbers in the deserts of the Saharan interior. They occur sporadically, however, in the coastal areas, where they are sympatric with Meriones libycus. In the interior, this species prefers areas of abundant sand and is oc- casionally taken in areas where large dunes are present; it is never found associated with mesic habitats. Throughout the range in Libya, these jirds occur together with many species of rodents but most frequently are taken with repre- sentatives of Gerbillus gerbillus, Gerbillus pyramidum, and Gerbillus amoenus. Meriones caudatus amplus, new subspecies Houoryps. Adult male, skin and skull, USNM 322681, from El Gatrun, Fezzan Province, Libya; obtained Jan. 8, 1962, by G. L. Ranck, original no. 1245. SPECIMENS EXAMINED. Twenty-three, from Frzzan: Meseguin, 8; Traghen, 2; 28 km E Murzuch, 3; El Gatrun, 10 (1 skin only). MrAsuREMENTS. Averages and extremes of four adult males and measurements of two adult females, 322677 and 322679, all from the 166 U.S. NATIONAL MUSEUM BULLETIN 275 type locality, with the measurements of the type in brackets, are, respectively: Total length 316.8 (302-335), 318, ?, [335]; length of tail 160.8 (151-175), 166, ?, [175]; length of hind foot 38.8 (386-41), 39, 39, [40]; length of ear 21.3 (20-23), 21, 20, [21]; greatest length of skull 42.2 (41.5-42.8), 42.1, 44.3, [42.8]; length of palate 18 (17.5- 18.5), 18.2, 17.8, [18.5]; length of audital portion of auditory bulla 16.2 (15.6-16.7), 16.4, 16.7, [16.7]; alveolar length of upper molariform toothrow 5.6 (5.5-5.9), 5.5, 5.9, [5.5]; least interorbital breadth 7.6 (7.5-7.8), 7.1, 7.6, [7.5]; length of nasals 15.9 (15.5-16.2), 15.9, 16.7, [16.2]; breadth of rostrum at level of antorbital foramina 4.1 (4—4.2), 4.1, 4.4, [4.2]; greatest breadth across zygomatic arches 23 (22.2—23.7), 22.5, 22.3, [23.7]. Diacnosis. Upperparts rich, lustrous, normally ranging from Ochraceous-Tawny to Buckthorn Brown and with moderate admixture of blackish-tipped hairs; in some paler specimens, the color of the dorsum approaching Cinnamon-Buff and uniformly colored through- out; long, silky guard hairs projecting 8 to 10 millimeters beyond the level of the underlying pelage, particularly on the rump; sides and scapular areas lightly washed with gray; distinct whitish and buffy patches present above the eyes, between the ears and the eyes, and below and behind the ears; in the pale color phase, these patches almost pure white and contrasting markedly with the surrounding pelage; mystacial, rostral, and circumoral areas ranging from buff to pure white; eye ring black; pinnae of ears long, sparsely haired, and in some specimens, almost naked; prominent row of buffy hairs projecting from the anterior margin of the pinna into the internal surface; vibrissae long, formed largely of white hairs, and sometimes extending posteriorly for 25 millimeters beyond the level of the ears; dorsal surfaces of fore and hind feet pure white; palmar surfaces naked; ventral surfaces of hind feet densely furred but with promi- nent hairless areas occupying the proximal one-half of the plantar surface; both fore and hind feet with five digits with dark-colored claws; tail exceedingly long for the species, and with a conspicuous black pencil extending over the distal one-third of the dorsal surface and continuing onto the ventral surface for perhaps 25 millimeters; tail unicolorous in the dark color phase, except for some faint suffusions of black hairs dorsally; tail contrastingly bicolored in the pale color phase, Cinnamon-Buff dorsally and almost pure white ventrally; entire underparts usually pure white, but in some speci- mens, with faint suffusion of buff. Skull: Extremely large, angular, and massive; zygomata strong and robust; auditory bullae markedly inflated both ventrally and laterally; lateral meatal expansions strongly inflated and firmly adpressed to squamous portion of tem- poral bone; suprameatal triangle small, elliptical in shape, and RODENTS OF LIBYA 167 completely enclosed by enveloping processes of the temporal and supraoccipital bones. Comparisons. From representatives of Meriones caudatus caudatus from 55 kilometers southwest of Bir Allagh, Tripolitania, the type and paratypes of M. c. amplus differ in much larger and more robust crania, particularly the zygomata, larger overall size, and noticeably lighter dorsal pelage with less suffusion of black. Meriones caudatus amplus also has proportionately smaller molariform teeth, and the lateral meatal expansion is less closely adpressed to the squamous portion of the temporal bone. Members of this new subspecies can be easily distinguished from those of Meriones caudatus confalonier from coastal Tripolitania and Cyrenaica by markedly larger and more robust skulls, larger overall size, and paler dorsal coloration. Meriones caudatus amplus can be distinguished from Meriones caudatus luridus from the vicinity of Giarabub, Cyrenaica, by larger size of skull and external dimensions, more conspicuous pencil, and darker (less yellowish) dorsal color, particularly that of the tail. Remarks. In its much larger size, both cranially and in external features, Meriones caudatus amplus is clearly distinct from all other subspecies of Meriones caudatus. In color, it is closest to Meriones caudatus caudatus of the Tripolitanian deserts, although it has much less black on the dorsum. Cranially, this subspecies most nearly resembles Meriones caudatus luridus from northeastern Cyrenaica. The latter is also a form of rather large cranial size, but MZ. c. amplus is still significantly larger. Except for a few specimens representing Meriones crassus from Umm el Abid, Zieghen, and the “Serir’”’ of Murzuch, collected by Edward Dodson of the Whitaker Expedition to Tripoli in 1901, the present series constitutes the first record of occurrence of members of this genus from the Fezzan. Because of larger size, M. c. amplus might well be regarded as a distinct species, but because of general resemblance to other sub- species of M/. caudatus in color, body form, general external characters and in proportions, shape, and configuration of the skull, probably it represents only an extreme in a clinal gradient. This subspecies shows no evidence of gene exchange with Meriones caudatus caudatus to the north. The Gebel es Soda and the barren areas of the Hamada de Tinrhert and Hamada el Hamra apparently restrict interbreeding between populations of these two subspecies. This apparent allopatry has resulted in morphological divergence in the Fezzanese populations, and this subspecies actually may represent an incipient species. 168 U.S. NATIONAL MUSEUM BULLETIN 275 In the Fezzan, these large rodents are known from comparatively few localities. No specimens are available from northern and western Fezzan, although suitable habitat is widespread, particularly in the vicinity of the oases of Sebha, Temenhint, Brach, Edri, El Abiad, Ubari, and Ghat. Future collecting in these areas, however, will probably reveal the presence of these jirds. The specimens available at present are almost indistinguishable morphologically, which suggests a free interchange of genes within and between populations in the eastern Fezzan. Two distinct color phases, a dark and a light phase, are present among the specimens from Meseguin and El Gatrun; some are intermediate in color. Animals representing all these color types are indistinguishable, however, in cranial characters. Therefore these wide ranges of color types suggest a variable genotype for color and do not indicate basic genetic differ- ences. At present, specimens are too few in number and are from too few localities to allow any generalizations about the full extent of variation among the various populations in the Fezzan. These jirds from the Fezzan are clearly not closely related to any other subspecies of M. caudatus in Libya and probably have closer affinities with populations in southern Algeria, Niger, or the northern Chad. EcoLoGicaL OBSERVATIONS. These jirds apparently require loose sand for their burrows. At all collecting sites, areas of pure sand or small dunes formed the dominant habitats, and specimens were never taken in areas devoid of sand. At the type locality at El Gatrun, a good series was obtained from the small dunes and sandy areas inter- spersed among the date palms. Frequently, these large rodents were caught in traps set upon sandy elevations having a dense cover of young palms. Usually in these habitats, large burrows are visible beneath the palms. The collecting sites near Murzuch, Traghen, and Mesequin were all characterized by areas of loose sand associated with densely growing, bushlike date palms. Apparently they do not occur in the marginal areas of the oases where areas of loose sand and date palms usually are lacking. These marginal habitats are typically hamada-like, and if vegetation is present, it consists of Tamarix and Calligonum growing upon isolated clay hummocks or sporadic growths of small, succulent plants inter- spersed on barren playas. In areas of loose sand, tracks and pathways of these jirds are wide- spread and usually extensive complexes of burrows are present. On several occasions, specimens were taken from traps set within or near entrances to burrows. Only rarely were traps holding full adults found in position in the trapline. Generally they were found dead several feet distant from the nearest trap, apparently after having been fatally struck. RODENTS OF LIBYA 169 At El Gatrun some of these jirds were purchased from the Arab inhabitants and had presumably been living commensally with them. This is not surprising in view of the sandy floors and hastily built structures in which these people live. Jirds are primarily nocturnal, but on one occasion at El Gatrun, an old adult male, 322672, was shot in full daylight while it foraged near the base of a clump of palms. Gerbillus pyramidum is commonly associated with M. c. amplus in these sandy habitats but is always much more abundant. The smaller Gerbillus gerbillus occurs less frequently with these jirds. The name amplus, from the Latin meaning large or largest, refers to the large size of members of this subspecies. Meriones caudatus caudatus Thomas Meriones libycus caudatus Thomas, Ann. Mag. Nat. Hist., ser. 9, vol. 3, p. 267, March 1919 (Tamari-Fergian, Tripolitania, Libya). SPECIMENS EXAMINED. Thirty-four, from TrrpoLiTania: 40 km ENE, Nalut, 2; 5 km N Mizda, 1; 55 km SW Bir Allagh, 19; 5 km E Derg, 6; 2 km SW Hun, 5; Bir Fergian, 1 (skin only). MEASUREMENTS. Averages and extremes of five adult males and five adult females from 55 kilometers southwest of Bir Allagh, are: Total length 282 (268-298), 276.8 (270-282); length of tail 141.4 (130-151), 138.8 (135-142); length of hind foot 35.8 (84-38), 33.8 (33-35); length of ear 18.4 (17-19), 17.8 (16-19); greatest length of skull 38.7 (37.5- 39.7), 38.3 (387.4-39.5); length of palate 15.6 (15.3-16.1), 15.6 (15.3- 16); length of audital portion of auditory bulla 14.7 (14-15.7), 14.8 (14.3-15.4); alveolar length of upper molariform toothrow 5.3 (4.8- 5.5), 5.3 (5.2-5.5); least interorbital breadth 7 (6.8-7.1), 6.8 (6.5— 7.3); length of nasals 14.7 (13.8-15.4), 14.7 (14.4-15); breadth of rostrum at level of antorbital foramina 4 (3.9-4.1), 3.9 (3.7-4.1); greatest breadth across zygomatic arches 20.9 (19.9-21.7), 20.5 (20-21). Driaecnosis. Pelage of dorsum silky and lustrous with long guard hairs projecting beyond shorter underlying buffy hairs; upperparts Cinnamon-Buff grading to Pinkish Buff on sides and flanks; all parts of dorsum strongly suffused with black, being particularly concen- trated on rump; in most specimens, supraorbital and postauricular patches prominent, Pale Pinkish Buff, frequently persisting as in- distinct pale areas anterior to pinnae; eye ring black; circumoral and mystacial areas, cheeks, and chin pure white, in some specimens, with faint suffusion of buff; pinna of ear densely furred, same color as dorsum, with distinct row of buffy hairs along anterior margin; dorsal surfaces of fore and hind feet usually pure white, but, in some speci- mens, with slight suffusion of buff; palmar surfaces naked; plantar surfaces naked proximally, densely furred distally and almost pure white; fore and hind feet each with five digits with claws, the latter 285-134 O—68——12 170 U.S. NATIONAL MUSEUM BULLETIN 275 dark-colored basally and pale-colored distally; vibrissae relatively long, formed from both light and dark-colored individual hairs, and extending well beyond the level of the ears; tail relatively long, dorsal surface about same color as dorsum, but more heavily suffused with black, and ventral surface uniformly Pinkish Buff; prominent black pencil occupies terminal one-third of the dorsal surface of the tail and extends along the ventral surface one-half this distance. Skull: Medium in size; auditory bullae markedly inflated both laterally and ventrally ; lateral meatal expansion large and applied to squamous part of the temporal bone; suprameatal triangle small, elliptical, and completely enclosed by enveloping processes of the temporal and supraoccipital; anterior portion of basioccipital and body of basisphenoid reduced to narrow rod-shaped structures between the large bullae. Comparisons. From topotypes of Meriones caudatus luridus, a single topotype of Meriones caudatus caudatus, 302246, from Bir Fergian, and near topotypes of M. c. caudatus from near Hun, Derg, and Bir Allagh, Tripolitania, differ in having dorsal pelage more heavily suffused with black, shorter tails with more prominent pencils (black rather than brownish) and being significantly smaller in all cranial measurements except the length of the upper molariform toothrow. When representatives of M. c. caudatus are compared with topotypes of Meriones caudatus confalonierti, the latter differs in slightly paler color of the dorsum and slightly smaller size of most cranial characters, being comparable in least interorbital breadth and width of rostrum. In general body size animals of the two subspecies are almost in- distinguishable. Although the above characters are somewhat tenuous, and M. c. confalonierii is poorly defined morphologically, the dif- ferences are still sufficient for separating subspecies, and I prefer to regard M. c. confalonierti as a valid form. For comparison with M. ec. amplus, see account of that subspecies. Remarks. A single topotype, 302246, from Bir Fergian, 10 kilo- meters south of Socna, Tripolitania, agrees closely in external measure- ments and color with the original description of Meriones libycus caudatus Thomas (1919, p. 267). Unfortunately, the skull of this single topotype was inadvertently lost, and cranial comparisons are not possible. Cranial measurements of representative series from nearby localities are decidedly smaller than those of the type specimen. I have not examined the type specimen of Meriones libycus caudatus (=Meriones caudatus caudatus), but judging from the literature, probably it represents an extremely old and outsized male which is not entirely representative of this subspecies. The various populations of this subspecies in Tripolitania are rather uniform in cranial characters, but some local variation is present in RODENTS OF LIBYA LZ dorsal color. Two specimens from near Nalut, 321833 and 321834, are the darkest dorsally of any of the Libyan populations of this subspecies and have more orange on the dorsal surface of the tail. Specimens from Derg, 321842, and Mizda, 321862, are noticeably paler dorsally than other representatives of this subspecies. Judging from the morphological homogeneity within and between the various populations, these jirds must interbreed freely throughout their range in Tripolitania. The vast expanses of the Hamada el Hamra and the rugged escarpments of the Gebel Nefusa have proved ineffective as deterrents to dispersal of this subspecies. To the north- east, however, the more humid coastal areas apparently provide unsuitable habitats, and to the south, the Hamada de Tinrhert and Gebel es Soda have retarded or entirely prevented gene exchange with the Fezzanese populations. Specimens are not available from localities between the ranges of M. c. caudatus and M. c. confalonieri to the northeast and M. c. amplus to the south; however, when specimens do become available from these areas, they probably will show intergradation between M. c. caudatus and these contiguous subspecies. ECOLOGICAL OBSERVATIONS. These jirds are unknown from localities outside Tripolitania but have disjunct distribution throughout the hamadas and oases of the interior. Their range includes the inner portions of the broad coastal plain of northwestern Tripolitania. The climate and terrain here are not unlike those of the inland deserts and generally are not typical of the coastal plain. In Tripolitania, representatives of this subspecies were collected from a wide variety of habitats as follows: Nalut: Localized, vegetated dunes supporting Calligonum and bushy, thorny perennials. Numerous burrows were present throughout the trapline, most of which were probably made by gerbils. Mizda: Occasional mounds and hard eleva- tions in the bottom of a badly eroded wadi. The vegetative cover con- sisted primarily of two species of thornbush growing among the hummocks. Bir Allagh: An isolated concentration of sandy-clay hillocks supporting thornbush in the midst of otherwise barren hamada. Derg: Margins and bottom of a shallow wadi with occasional hillocks of sand interspersed with denuded rock-strewn areas. Most of the trap settings were made near the entrances of active burrows. Hun: Large, localized permanent mounds supporting almost impene- trable growths of a thorny perennial in the midst of an extensive sandy plain. These rodents are normally nocturnal, but near Hun, a subadult specimen was caught in full daylight only a few seconds following the setting of the trap. At the various collecting sites in Libya, they occurred with Meriones libycus; Gerbillus aureus; Jaculus jaculus; Gerbillus campestris; Jaculus E72 U.S. NATIONAL MUSEUM BULLETIN 275 deserti; Pachyuromys duprasi; Gerbillus gerbillus; Gerbillus pyramidum; Gerbillus amoenus; Gerbillus eatoni; and Acomys cahirinus. Meriones caudatus confalonierii de Beaux Meriones libycus confalonierti de Beaux, Ann. Mus. Stor. Nat. Genova, vol. 55, p. 384, 1931 (El Agheila, Cyrenaica Province, Libya). SPECIMENS EXAMINED. Seven, from CyrEenaica: 5 km W El Agheila, 5; from TRIPoLITANIA: 15 km WNW Marble Arch, 2. MEASUREMENTS. Measurements of an adult male, 302229, and averages and extremes of four adult females from 5 kilometers west of El Agheila, are, respectively: Total length 277, 280.5 (277-284) ; length of tail 143, 146.5 (145-148) ; length of hind foot 34, 34.5 (34-36) ; length of ear 18, 18.3 (18-19); greatest length of skull 36.4, 36.8 (36-37.4); length of palate 15.3, 15.1 (14.2-15.8); length of audital portion of auditory bulla 13.9, 14.4 (13.7-15); alveolar length of upper molariform toothrow 4.9, 5.1 (5—-5.3); least interorbital breadth 6.4, 6.6 (6.2-6.8); length of nasals 13.5, 13.2 (12.7-13.5); breadth of rostrum at level of antorbital foramina 3.9, 3.8 (3.7-3.9); greatest breadth across zygomatic arches 19.3, 19.8 (19—20.4). Driaenosis. Identical to that of Meriones caudatus caudatus as given in the preceding account, except for the slightly paler dorsal pelage with less suffusion of black and the more brownish color of the pencil. Cranially, confalonierii is smaller than caudatus in almost all respects but in general salient features of the skull, there are no significant differences. Comparisons. This subspecies can be easily distinguished from both Meriones caudatus amplus of the Fezzan and Meriones caudatus luridus from northeastern Cyrenaica by its markedly smaller, more gracile skull and much smaller overall size of body. For detailed comparison with Meriones caudatus caudatus, see under “comparisons” in account of that subspecies. Remarks. Most of the specimens considered here are topotypes of Merwones caudatus confaloniertt and agree rather closely with measure- ments and descriptions as given by de Beaux (1932) in the original description. Setzer (1957) had seven specimens from El Agheila, two of which he erroneously assigned to Meriones libycus confaloniertt (= Meriones caudatus confalonierii). He also referred a single specimen (skull only, 302311) from Zliten, Tripolitania, to this subspecies. Actually, these three specimens belong to Meriones libycus auratus (then Meriones shawi shawi) and are specifically different from the other five specimens from El Agheila, which were correctly assigned to Meriones libycus confalonierit. The species M. libycus and M. caudatus thus occur sympatrically at El Agheila. RODENTS OF LIBYA 173 This coastal subspecies is known from only the type locality at El Agheila, Cyrenaica, and from Marble Arch in Tripolitania. Its range, however, probably includes most of the coastal plain and transitional desert along the Gulf of Sirte as far east as Benghazi. The more mesic uplands of the Cyrenaican Plateau and Gebel Achdar which are interposed between the ranges of this subspecies and that of Meriones caudatus luridus to the east, provide unsuitable habitats for these jirds. The coastal plain also is markedly reduced or absent in many places in northern Cyrenaica and serves to further limit the extent of habitats suitable for jirds and tends to reduce gene flow be- tween the two subspecies. There are no physical barriers separating the range of M. c. confalonierii from that of M. c. caudatus to the south, but apparently the more arid climate farther inland is unsuitable for members of this coastal subspecies. Some intergradation doubtless takes place between these two subspecies somewhere in the transitional desert south of the Gulf of Sirte. EcoLoGIcaL OBSERVATIONS. This subspecies is apparently confined to the more humid habitats of the coastal plain and littoral deserts surrounding the Gulf of Sirte in Cyrenaica and Tripolitania. The two specimens from near Marble Arch were collected from the northern- most terminus of the coastal hamada overlooking the coastal plain. Vegetative cover here was sporadic, localized, and somewhat transi- tional between that of the more densely vegetated coastal plain and the much sparser plant cover of the hamadas farther inland. Setzer (1957) describes the habitat at El] Agheila as consisting of sandy areas with a good vegetative cover. He also observed large, shallow burrows located under bushes and containing from three to eight entrances. Seeds and leaves of locally common plants were found in the burrows. Meriones caudatus luridus, new subspecies Hototypr. Adult male, skin and skull, USNM 325597, from Bahr el Tubat, 21 km ESE Giarabub, Cyrenaica Province, Libya; obtained May 29, 1962, by G. L. Ranck, original no. 2187. SPECIMENS EXAMINED. Twenty-nine, from Cyrenaica: 11 km E Ain el Gazala, 2; 10 km SW Fort Capuzzo, 1; 60 km S Bir el Gobi, 17; Giarabub, 2; Bahr el Tubat, 21 km ESE Giarabub, 5; 24 km SSE Giarabub, 2. MEASUREMENTS. Measurements of an adult male, 325598, from the type locality, and the measurements of an adult female, 302317, from Giarabub, with the measurements of the type in brackets, are, respectively: Total length 268, 240, [291]; length of tail 131, 123, [155]; length of hind foot 34, 32, [36]; length of ear 18, 17, [19]; great- est length of skull 39, 38.6, [40]; length of palate 16.6, 16, [16.3]; length of audital portion of auditory bulla 14.6, 14.5, [15.3]; alveolar 174 U.S. NATIONAL MUSEUM BULLETIN 275 length of upper molariform toothrow 5.1, 5.1, [5.4]; least interorbital breadth 7.5, 6.4, [7.4]; length of nasals 14.8, 14.5, [15]; breadth of rostrum at level of antorbital foramina 4, 3.6, [3.6]; greatest breadth across zygomatic arches 20.6, 20, [20.5]. Diacnosis. Upperparts subdued in color varying in tones of Ochraceous-Buff, Light Ochraceous-Buff, Warm Buff and Pinkish Buff; all parts faintly washed with gray; postauricular patches distinct, almost pure white; region around eyes light gray strongly suffused with black; cheeks and circumoral areas white; eye ring black; vi- brissae long, formed of about equal numbers of black and white hairs; pinna of ear sparsely haired, particularly on medial aspect and with distinct row of buffy hairs along anterior margin; fore feet naked ventrally, buffy-white dorsally and bearing five digits with dark- colored claws; hind feet heavily haired ventrally, except for a promi- nent hairless area confined to proximal half of plantar surface, white dorsally and also bearing five digits with claws; tail relatively long, unicolorous, slightly paler than that of the dorsum, with prominent black pencil occupying distal one-fourth of dorsal surface and ex- tending a short distance along ventral surface. Skull: Relatively large and robust; zygomata heavy and coarse; anterior palatine fora- mina narrow and slitlike; auditory bullae large, markedly inflated both ventrally and laterally, and adnate to squamous portion of temporal bone; suprameatal triangle large and completely enclosed by enveloping processes of the supraoccipital and temporal bone. Comparisons. This new subspecies can be distinguished from both Meriones caudatus caudatus of the Tripolitanian deserts and Meriones caudatus confalonieria of the Tripolitanian and Cyrenaican coastal plains by its larger body size, being larger in all cranial measurements except breadth of rostrum, alveolar length of upper molariform toothrow, and zygomatic breadth. In external measurements, Meriones caudatus luridus is larger in greatest length and length of tail but of comparable length in the length of hind foot and ear. Although animals belonging to M. c. luridus are of large size, they still differ strikingly from M. c. amplus in having smaller and more gracile crania, particularly the zygomata, and smaller external measurements. In its markedly paler, more yellowish dorsal color, particularly that of the tail, and in the less conspicuous pencil, this subspecies differs strikingly from all other subspecies of Meriones caudatus. Remarks. Toschi (1951 and 1954) assigned specimens from the vicinity of Giarabub to Meriones libycus libycus and Meriones libycus caudatus. Sympatry of two subspecies of the same species is not in accordance with modern systematic and evolutionary concepts. In the present work, however, M. libycus and M. caudatus are considered RODENTS OF LIBYA 175 as separate species, and the above mentioned sympatry is to be expected. I have not examined Toschi’s specimens, but judging from his measurements, they most likely belong to Meriones caudatus luridus and not to Meriones libycus libycus. This does not preclude the pos- sibility that the latter species occurs at Giarabub. Representatives of both species occur sympatrically along the northern Cyrenaican coast and doubtless are sympatric throughout coastal Egypt. One specimen of M. c. luridus, 325586, from 11 kilometers east of Ain el Gazala on the northern Cyrenaican coast is almost identical in color to topotypical Meriones caudatus confalonieria from near El Agheila farther west in Libya. This is the only evidence of intergrada- tion with populations of MZ. caudatus to the west. The high tablelands of the Cyrenaican Plateau, the massif of the Gebel Achdar, and the marked reduction of the coastal plain apparently act as deterrents to gene flow between members of this subspecies and those farther west. Meriones caudatus luridus probably has greater affinities with jirds in western Egypt. Its range probably includes Giarabub Oasis and all of the inland hamadas south of the Cyrenaican Plateau in Libya, the Libyan Plateau of extreme northwestern Egypt, and the extensive low-lying areas of Siwa Oasis, the Qattara Depression, and the Wadi Natroun in Egypt. The barren vastness of the Serir of Calanscio and the Sand Sea of Calanscio, in Libya, and the desolate Western Desert in Egypt apparently limit the southward distribution of these jirds. This subspecies is known from comparatively few specimens and the full extent of its variation is unknown. Two specimens, 302316 and 302317, from Giarabub, however, are noticeably more orangish in dorsal color and lack the typical yellowish-buff color of the tail. A large series from south of Bir el Gobi, most of which are subadults, are constant in showing this pale yellowish dorsal color. EcoLoGIcaL OBSERVATIONS. In Libya, this subspecies is confined primarily to the hamadas and sandy deserts of the interior, but the collecting sites 11 kilometers east of Ain el Gazala and 10 kilometers southwest of Fort Capuzzo are less than 15 kilometers from the Mediterranean coast. In coastal areas, members of this subspecies occur together with those of Meriones libycus. The extent of the range of the latter species farther inland has not yet been ascertained, but the two species are probably sympatric throughout all of northeastern Libya and northwestern Egypt. These jirds have similar habitat preferences to populations of M. c. caudatus and M. c¢. confalonierii in western Libya, all having a decided predilection for sandy areas. The habitats at the following localities in Cyrenaica are characterized as follows: 11 km E Ain el 176 U.S. NATIONAL MUSEUM BULLETIN 275 Gazala: Series of vegetated sandy-clay hummocks near the roadside, many of which contained large open burrows. Most burrows were littered with plant debris and remnants of seeds. This site was situated on the extreme northern terminus of the coastal hamada and approxi- mately five kilometers from the Mediterranean Sea. 10 km SW Fort Capuzzo: A localized pocket of bushes and smaller perennials surrounded by almost barren hamada. Burrows were widespread in the coarse, sandy soil. 60 km S Bir el Gobi: Localized pockets of vege- tation bordering the sandy margins of a small wadi in the midst of an otherwise featureless and totally barren ‘“serir.” 24 km SSE Giarabub: Residual sandy-clay hummocks and lesser dunes inter- spersed in areas of loose sand in the bottom of a broad, enclosed wadi. Bahr el Tubat: Extensive concentrations of large vegetated dunes. At the latter two collecting sites, Gerbillus gerbillus, Jaculus jaculus, and Gerbillus campestris were taken along with these jirds. The subspecies name luridus, from the Latin meaning pale yellow or yellowish, alludes to the pale-yellow tones of the dorsal pelage. 36 37 38 39 40 4l 42 4B 44 Ficure 38.—Statistical comparison of greatest length of skull of the subspecies of Meriones caudatus: A, M. c. amplus; B, M. c. caudatus; C, M.c. confalonierii; D, M. c. luridus. Meriones crassus tripolius Thomas Meriones pallidus tripolius Thomas, Ann. Mag. Nat. Hist., ser. 9. vol. 3, p. 265, March 1919 (Gebel Limhersuk, in the northwest part of the country). GENERAL DISTRIBUTION OF SPECIES. West Pakistan, Afghanistan, southern Russian Turkestan, Iran, Iraq, Syria, Lebanon, Jordan, Israel, Saudi Arabia, Egypt (including Sinai), Libya, Algeria, and RODENTS OF LIBYA 177 the northern Sudan. The range probably also includes portions of Mauritania, Niger, and the Chad. DisTRIBUTION IN Lisya. Interior deserts of Tripolitania and the Fezzan; currently unknown from Cyrenaica, but probably occurs here also. SPECIMENS EXAMINED. Twenty-four, from TRripouirania: Gebel Limhersuk, 3 (BM); 5 kmS Socna, 4; Bir Fergian, 4 (BM; 2 skin only); from Frzzan: Brach, 1; Edri, 1; 26 km N Goddua, 1; 75 km W Ubari, 4; 55 km SSW Serdeles, 2; 20 km N Ghat, 2; 12 km N Ghat, 2 (one skull only). PUBLISHED RECORDS IN LiByaA. CyRENAICA: Sidi Sweya (Thomas, 1902); Trreotitanta: Wadi Agarib, Koshebey, Gebel Limhersuk (Thomas, 1902 and 1919 [Meriones schousboei Loche and Meriones pallidus tripolius]) ; FezzAN: Umm el Abid, Murzuch, Zieghen (Thomas, 1902); Bir el Fatia, Serdeles (Toschi, 1951). MEASUREMENTS. Measurements of two adult males, 322660 and 322662, and one adult female, 322659, from 75 kilometers west of Ubari, Fezzan, are, respectively: Total length 232, 232, 235; length of tail 114, 121, 121; length of hind foot 31, 30, 30; length of ear 17, 17, eo yk 7 KILOMETERS i ys Ng Meriones crassus tripolius Ficure 39.—Distribution of Meriones crassus tripolius. 178 U.S. NATIONAL MUSEUM BULLETIN 275 18; occipitonasal length of skull 36.5, 35.9, 35.5; length of palate 15, 15.2, 15.1; length of anterior palatine foramina 6.1, 5.7, 5.7; length of audital portion of auditory bulla 14.3, 13.8, 14.4; alveolar length of upper molariform toothrow 5.3, 5.7, 5.2; least interorbital breadth 5.7, 5.9, 5.8; length of nasals 13.4, 13.6, 13.6; greatest breadth across zygomatic arches 19.8, 19.3 19.9; breadth of rostrum at level of ant- orbital foramina 3.1, 3.4, 3.4. Diaenosis. Pelage of dorsum fine, silky and lustrous; varying in color from Light Ochraceous-Buff and Cinnamon-Buff to Pinkish Cinnamon; most specimens with mild admixtures of brown-tipped hairs on dorsum, which produce a slightly streaked or marbled ap- pearance; sides, supraorbital, preauricular, and subauricular regions with faint suffusions of gray; eye ring black or dark brown; circumoral and mystacial areas, and conspicuous postauricular patches Pinkish Buff; pinna of ear densely haired, about same color as dorsum, and with distinct row of buffy hairs along anterior margin; vibrissae long, formed of black and white individual hairs; forefeet almost pure white dorsally, naked ventrally and with five digits bearing pale- colored claws; hind feet usually white dorsally, with thick covering of hairs ventrally, except for conspicuous hairless areas on proximal halves of plantar surfaces, and also with five digits bearing pale- colored claws; tail relatively short for the species, Pinkish Buff in color, appearing bicolored owing to slight admixture of black hairs dorsally, and with distinct brush of black or dark brown hairs distally. Skull: Relatively small and gracile for the species; auditory bullae large and bulbous, noticeably inflated ventrally, laterally, and poste- riorly, but to a lesser extent than in other subspecies; lateral meatal expansion closely applied to squamous portion of temporal bone; suprameatal triangle large, triangulariform, and imperfectly closed posteriorly by enveloping processes of the supraoccipital and temporal bones. Comparisons. From representatives of Meriones crassus crassus Sundevall from the vicinity of Feiran Oasis and St. Catherine’s Monastery, Sinai, Egypt, paratypes of Meriones crassus tripolius from Tripolitania and representatives of M. c. tripolius from various localities in the Fezzan differ in darker dorsal color, shorter and less inflated auditory bullae, less robust zygomata, and generally much smaller size of cranium and all external dimensions. Compared to representatives of Meriones crassus pallidus Bonhote from the Eastern Desert Governorate, Egypt, M. c. tripolius differs in the same characters as given for M. c. crassus. Adult specimens of M. ¢. asyutensis Setzer are not available for comparison, but judging from the original description (Setzer, 1961), they are significantly RODENTS OF LIBYA 179 larger than those of M. c. crassus and, by inference, must be markedly larger than those of M. c. tripolius in every detail. Meriones crassus can be distinguished easily from both Meriones libycus and Meriones caudatus by larger and more posteriorly inflated auditory bullae, larger suprameatal triangles with open posterior processes rather than closed or closely approximating as in M. libycus and M. caudatus, shorter tail, and generally paler, more uniform dorsal color. Remarks. Setzer (1961) described Meriones crassus perpallidus from Cairo-Alexandria Road, 4 kilometers from Cairo, Egypt, and stated that it differed from representatives of Meriones crassus tripolius by paler dorsal color, larger, more massive skull, wider, shorter rostrum, and more posteriorly inflated auditory bullae. When paratypes of these two subspecies are compared, however, M. c. tripolius can be most easily distinguished from M. c. perpallidus by darker dorsal color, with stronger suffusion of brownish hairs, and by markedly smaller size of external dimensions. Paratypes of M. c. tripolius also have slightly larger and more massive skulls, rather than smaller skulls as stated by Setzer, and the mastoidal portion of the auditory bulla is less inflated posteriorly. The breadth and length of the rostra do not differ appreciably in paratypes of M. c. tripolius and M. c. perpallidus. When Setzer described M. c. perpallidus, he had only a few specimens of M. c. tripolius from Tripolitania and apparently did not examine typical specimens of M. ec. tripolius from the Gebel Limhersuk. In the present work, paratypes of both subspecies are at hand, some additional characters by which these two subspecies differ are noted, and some of the differences set forth by Setzer are not apparent. Thomas (1902) assigned specimens obtained by Edward Dodson in 1901 from several localities in Tripolitania and the Fezzan to Meriones schousboei Loche. In a later paper (1919), using these same specimens, he described Meriones pallidus tripolius (= Meriones crassus tripolius) with the type locality at Gebel Limhersuk, Tripolitania, and named Meriones libycus caudatus from Tamari-Fergian, Tripolitania. He did not ascribe a specific range to either species, however, and in no way indicated to which of the above species the specimens from the Fezzan might be referred. Many years later, Chaworth-Musters and Ellerman (1947) assigned these Fezzanese specimens to Meriones Crassus. Since Thomas described Meriones pallidus tripolius (= Meriones crassus tripolius) in 1919, this subspecies has had an uncertain status. It was first treated as a subspecies of Meriones libycus (Ellerman, 1941), later considered as a subspecies of Meriones crassus (Ellerman, 1947 and Chaworth-Musters and Ellerman, 1947), and finally regarded as 180 U.S. NATIONAL MUSEUM BULLETIN 275 a synonym of Meriones crassus crassus (Ellerman and Morrison-Scott, 1951 and Toschi, 1954). More recently, Setzer (1957) reinstated M. c. tripolius as a valid subspecies of M. crassus and assigned specimens from near Socna and Bir Fergian, Tripolitania, to it. He stated that these jirds from Libya were markedly paler and had smaller skulls with particularly less inflated posterior portions of the auditory bullae than typical specimens of M. c. crassus from Sinai. Thomas (1919), in the original description of Meriones pallidus tripolius, said that it was very near to Meriones pallidus (= Meriones crassus pallidus), of the Sudan, but with smaller auditory bullae and slightly darker dorsal color. Throughout the known range in Libya, populations of these jirds are remarkably uniform in cranial characters and dimensions. Jirds from several localities in the Fezzan clearly belong to this subspecies but differ from topotypes of M. c. tripolius from farther north in Tripolitania in having slightly more gracile skulls, more delicate zygomata, and in being slightly smaller in external dimensions. In color, all Libyan representatives of this subspecies are inseparable. Two specimens, a very old male (BM, no. 34.8.2.64) and an old female (BM, no. 34.8.2.65) from El Golea, Algerian Sahara, are comparable in color and external measurements to the specimens from Libya but are noticeably larger cranially. This larger size of the Algerian specimens may result from increased angularity and thickening of the skull attributable to extreme old age. EcoLoGicaL OBSERVATIONS. In Libya, these jirds are represented by comparatively few specimens from Tripolitania and the Fezzan and are unknown from Cyrenaica. Several days of intensive trapping at the oases of Brach and Edri in the Fezzan produced only two specimens, both from the hamada-like plains several kilometers distant from the palm groves and sand of the oases proper. Near Ghat and Ubari they inhabited the margins of shallow wadis that dissected the desolate, flat hamada. At all these collecting sites, vegeta- tive cover was reduced to occasional bunches of dry grasses and scattered acacias. One evening in January, while I camped on the barren plain 26 kilometers north of Goddua, Fezzan, a single male specimen, 322693, was captured alive when it approached to within a few feet of the lantern. Visible vegetation at this campsite was entirely lacking except for a distant solitary acacia tree. These hardy rodents seem to prefer the more barren hamadas and sparsely vegetated wadis located some distance from oases and were never collected from dunes or sandy areas within palm groves. In the latter habitats, however, the larger, more bushy-tailed Meriones caudatus is rather common. Because of their preference for these marginal habitats, specimens of M. crassus are obtained only rarely and are poorly RODENTS OF LIBYA 181 represented in collections. The present series probably provides a very incomplete picture of their actual distribution in Libya. The jirds obtained by Edward Dodson, plus additional specimens from Bir el Fatia and Serdeles (Toschi, 1951), those obtained by Setzer (1957) from near Socna and Bir Fergian, and the present series collected by the author from the Fezzan constitute the only known records of occurrence of Meriones crassus in Libya. Meriones libycus Lichtenstein Meriones libycus Lichtenstein, Verzeich. Doubl. Zool. Mus. Berlin, p. 5, no. 9, 1823 (Lichtenstein gives the type locality as ‘‘e deserto libyco,”’ but Ellerman and Morrison-Scott [1951:644] limit the type locality to ‘‘Near Alexandria.’’) GENERAL DISTRIBUTION OF SPECIES. Russian Turkestan, Chinese Turkestan, Transcaucasia, Kara-Kum, Kizil-Kum, Iran, Baluchistan (West Pakistan), Afghanistan, Iraq, Syria, Israel, Saudi Arabia, Sinai, Egypt, Libya, Tunisia, Algeria, and Morocco. DIsTRIBUTION IN LiByA. Coastal plain and littoral deserts of Cyrenaica and Tripolitania. DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Meriones libycus azizi. CYRENAICA: Coastal areas of extreme northern Cyrenaica. Meriones libycus auratus. CyrENAIcA and TRIPOLITANIA: Coastal plain of Gulf of Sirte and Tripolitania as far inland as the coastal escarpment. PUBLISHED RECORDS IN LisByA. CyrENAICA: Bou Cheifa (Thomas, [Meriones shawi shawi] 1902); Benghazi, Gheminez (Festa [Meriones guyoni Loche], 1921); Giarabub and vicinity (de Beaux, 1928); Augila (de Beaux [Meriones guyoni], 1932); Derna (Zavattari, 1934); Merg (=Barce) (de Beaux, [Meriones shawi shauwi] 1938); Benghazi, Gheminez (Toschi, [Meriones shauwi shawi] 1951); TRIPOLITANIA: Wadi Aggar, Wadi Nefed, Tarhuna (Thomas, [Meriones shaun shawi] 1902). Comparisons. This species can be readily distinguished from Meriones crassus by coarser, less silky fur, markedly smaller and less inflated auditory bullae, and smaller suprameatal triangles with more closely approximating posterior processes. From a single specimen (MNHN, no. 704) of Meriones shaw, as known from Guelt es Stel, Algeria, and two specimens (BM, nos. 60.8.25.12 and 60.8.25.13) identified as Meriones robustus Wagner (= Meriones shaun [Loche, 1867]) from an unknown locality in Algeria, representatives of M. libycus from Libya and Egypt are noticeably smaller cranially and have proportionately larger and more inflated auditory bullae. In color and external measurements, the specimen from Guelt es Stel is similar to representatives of M. libycus in Libya. 182 U.S. NATIONAL MUSEUM BULLETIN 275 EER Le? KILOMETERS Meriones libycus I. azizi 2. guratus Ficure 40.—Distribution of the subspecies of Meriones libycus. The other two specimens representing Meriones robustus are much darker and markedly larger in all external characters. Compared to Meriones caudatus, Meriones libycus differs in having a markedly shorter tail with a less conspicuous pencil of brown rather than black, smaller and less inflated auditory bullae, and suprameatal triangles which are usually more nearly round in shape, rather than elliptical, and imperfectly enclosed rather than completely enclosed by enveloping processes of the supraoccipital and temporal bones. Remarks. Thomas (1902) referred specimens from various localities of coastal Libya to Meriones shawi. More recently, Toschi (1954) and Setzer (1957) also considered specimens from coastal Cyrenaica and Tripolitania as subspecies of M. shawi. Setzer had no specimens of shaui for comparison, and the above assignments were based largely on the similarities of measurements between the Libyan specimens and those of typical M. shawi. I have examined those specimens available to Setzer and additional series from other coastal localities in Libya and find them all referable to M. libycus of Egypt. These Libyan populations differ slightly from typical M. libycus from the vicinity of the Nile and western coastal Egypt, but these differences RODENTS OF LIBYA 183 are subtle, being typical of subspecies and not of species. In my opinion, specimens from coastal Libya, formerly referred to M. shawi, actually belong to AZ. libycus, and if M. shawi is a valid species, its range is limited to Algeria and areas to the south and west. This species is represented in Libya by two subspecies, Meriones libycus auratus and Meriones libycus azizi. As presently understood, its range in Libya is limited to the Mediterranean littoral as far inland as the coastal escarpment. Apparently the range of the nominate subspecies does not include Libya. Specimens from Sidi Barrani, Salum, and Mersa Matruh of western coastal Egypt, although geo- graphically not far removed from the type locality of M. l. azizi, are clearly referable to M. l. libycus. Meriones libycus auratus, new subspecies Ho.uotyrr. Adult male, skin and skull, USNM 302233, from Gheminez, Cyrenaica Province, Libya; obtained Oct. 29, 1955, by H. W. Setzer, original no. 2672. SPECIMENS EXAMINED. Sixteen, from Cyrenaica: Gheminez, 9; 5 km W El Agheila, 2; from Tripoxrtanta: 12 km W Zliten, 3 (1 skull only; 1 skin only); 40 km ENE Nalut, 2. MEASUREMENTS. Averages and extremes of four adult males and three adult females from the type locality, with the measurements of the type in brackets, are, respectively: Total length 273.5 (269-282), 266.5 (260-273), [269]; length of tail 138 (135-143), 133.5 (132-135), [137]; length of hind foot 34 (33-35), 32.7 (32-34), [35]; length of ear 16.8 (16-18), 16 (15-17), [16]; greatest length of skull 37.5 (36.5-38.2), 36.5 (36.2-36.8), [37.1]; length of palate 16.5 (16.3-16.7), 16.2 (16.1- 16.3), [16.3]; length of audital portion of auditory bulla 13.3 (12.8- 13.4), 12.6 (12.3-12.8), [13]; alveolar length of upper molariform toothrow 5.6 (5.4--5.7), 5.5 (5.3-5.6), [5.6]; least interorbital breadth 6.2 (5.7-6.7), 5.9 (5.7-6.2), [6.1]; length of nasals 14.3 (13.7-14.9), 13.7 (13.6-13.9), [14.9]; breadth of rostrum at level of antorbital foramina 3.6 (3.5-3.8), 3.6 (3.4-3.7), [3.6]; greatest breadth across zygomatic arches 20.5 (19.8-21.4), 19.9 (19.5-20.3), |20.5}. Driacnosis. Upperparts ranging from Buckthorn Brown to Clay Color, becoming paler on sides and approaching Cinnamon-Buff; all of dorsum, including tail, evenly suffused with brownish-tipped hairs; postauricular patches conspicuous and almost pure white; supraorbital and preauricular patches conspicuous and almost white with strong admixture of black-tipped hairs; distinct white patch present on rostrum immediately behind origin of vibrissae; eye ring black; pinna of ear relatively short, remarkably uniform in color, but slightly darker distally and almost devoid of hair, except for a distinct row of pos- teriorly directed buffy hairs on anterolateral margin; vibrissae fine in 184 U.S. NATIONAL MUSEUM BULLETIN 275 texture, formed of both brown and white hairs, and extending caudad beyond the level of the ears; scapular regions, upper arms, and pectoral areas with moderate suffusions of buff; forefeet white dorsally, almost naked ventrally, and with five digits bearing claws; hind feet white dorsally and with five digits bearing dark-colored claws; plantar sur- faces heavily furred except for a small naked area on the ventral surface of the heel; tail, dorsally, approaching color of body and heavily suffused with brown-tipped hairs, and ventrally near Pale Pinkish Buff; a distinct brownish pencil occupying the distal one- fourth of the dorsal surface of the tail. Skull: Relatively small in size, auditory bullae short and well inflated ventrally; anterior palatine foramina relatively narrow; meatal expansion of auditory bullae with abrupt curvature and not applied to the squamous process of the temporal bone; suprameatal triangle rounded and with posterior processes imperfectly closed. Comparisons. The type series of Meriones libycus auratus can be easily distinguished from near topotypes of Meriones libycus libycus from the West Desert region of Egypt by markedly smaller and less robust crania, smaller overall size, especially the small size of the hind feet, and noticeably paler, more golden dorsal color. Members of this subspecies resemble rather closely those of Meriones libycus azizi from farther north and east in Cyrenaica but differ in having larger hind feet, wider interorbital breadths and rostra, and paler, more golden dorsal pelage with more prominent postauricular and supraorbital patches. Remarks. Representatives of this subspecies throughout coastal Libya are remarkably uniform in color and cranial characters. Two specimens, 321835 and 321836, from 40 kilometers east-northeast of Nalut on the Tripolitanian coastal plain are almost indistinguishable from those from the type locality in Cyrenaica, and specimens from El Agheila on the southern margin of the Gulf of Sirte do not differ appreciably from topotypes of M. l. auratus. This morphological homogeneity is the result of constant genetic exchange within and between populations of these jirds rendered possible by the almost uninterrupted continuity of suitable habitat of the Cyrenaican and Tripolitanian coastal plains. Setzer (1956) referred two specimens from El Agheila and a single specimen from near Zliten to Meriones libycus confalonierta (= Meri- ones caudatus confalonierii). These three specimens are specifically different from the other specimens found in these localities and clearly belong to Meriones libycus auratus. Regardless of their taxonomic status at that time this erroneous assignment is unaccountable as the two forms are easily separable: in the field, by the more bushy tail with prominent black pencil of M. caudatus and in the laboratory, by RODENTS OF LIBYA 185 the noticeably larger and more inflated auditory bullae and complete closure of the suprameatal triangles of M. caudatus. EcoLoGICAL OBSERVATIONS. These jirds apparently prefer areas of low elevation on the coastal plain and are unknown from the higher Saharan interior where they are supplanted by the bushy-tailed Meriones caudatus. At Nalut, two specimens, 321835 and 321836, were obtained from some large dunes near the coastal escarpment. These dunes supported a sparse vegetative cover of Calligonuwm and thorny perennials. Two specimens of M. caudatus and a large series of Gerbillus aureus were taken from the same trapline. According to Setzer (1957), the habitat at Gheminez and Zliten consisted of poorly vegetated rocky-clay type of soil and fallow barley fields. Although this subspecies is known from comparatively few speci- mens and has been collected from only four localities, it doubtless has a wide distribution and is probably sympatric with practically all other species of coastal rodents throughout the Mediterranean littoral of Libya. From the vicinity of El Agheila, it has been taken with Gerbillus eatoni, G. gerbillus, G. pyramidum, G. amoenus, G. henleyi, Pachyuromys duprasi, Meriones caudatus, and Psammomys obesus. At Gheminez, Jaculus orientalis, Allactaga, tetradactyla, and Gerbillus aureus occur with M. l. auratus. The subspecific name auratus is derived from the Latin “aurum,” meaning gold or of gold, and has reference to the golden cast of the dorsal pelage in members of this subspecies. Meriones libycus azizi Setzer Meriones shawi azizi Setzer, Proc. Biol. Soc. Wash., vol. 69, pp. 205-206, Dec. 31, 1956 (5 km SE Derna, Cyrenaica, Libya). SPECIMENS EXAMINED. Twenty, from Cyrenaica: 3 km E. Derna, 1; 5 km SE Derna, 2; 7 km E Maraua, 1; 2 km N Coefia, 5; 8 km N Benghazi, 2; 20 km E Tobruch, 9. MEASUREMENTS. Measurements of two adult females, 302243 and 325604, from 5 km SE Derna and 20 kilometers east of Tobruch are, respectively: Total length 259, 252; length of tail 131, 123, length of hind foot 32, 31; length of ear 17, 19; greatest length of skull 36.8, 36.4; length of palate 16.4, 16.5; length of audital portion of auditory bulla 12.3, 12.8; alveolar length of upper molariform toothrow 5.6, 5.7; least interorbital breadth 6.1, 5.7; length of nasals ?, 13.7; breadth of rostrum at level of antorbital foramina 3.2, 3.7; greatest breadth across zygomatic arches 20.4, 20.6. Diacnosis. Upperparts ranging from Snuff Brown to Buffy Brown becoming paler on sides and flanks and approaching Tawny-Olive; all of dorsum strongly suffused with blackish-brown hairs resulting 285-134 O—68——13 186 U.S. NATIONAL MUSEUM BULLETIN 275 in a uniformly variegated appearance; circumoral and rostral areas grading from Pinkish Buff to Cinnamon-Buff; area between ears and eyes washed with gray and appearing as a faint patch above the eye; scapular and pectoral areas, chin and upper surfaces of front legs and feet suffused with varying amounts of Pinkish Buff and Light Pinkish Cinnamon; forefeet sparsely haired ventrally with five digits bearing dark-colored claws. Hind feet Pale Pinkish Buff dorsally, richly haired ventrally except for a bare area near the heel, and with five digits with dark-colored claws; pinna of ear mod- erately haired, becoming darker distally and approaching Saccardo’s Umber, with a conspicuous row of buffy hairs along entire antero- lateral surface; eye ring black; vibrissae formed of both black and white hairs and projecting backward to the level of the ears; tail Cinnamon and appearing somewhat bicolored owing to strong ad- mixtures of blackish hairs dorsally and with a distinct black pencil confined to the dorsal surface for about the distal one-fourth. Skull: Small in size; auditory bullae short and expanded ventrally; zygomatic arches wide; anterior palatine foramina wide; suprameatal triangles round in shape with posterior processes imperfectly closed. Comparisons. From near topotypes of Meriones libycus lbycus from various localities in western coastal Egypt, the type specimen and a paratype of Meriones libycus azizi have significantly smaller cranial and external measurements and shorter and more inflated auditory bullae. In color, the two subspecies are quite similar. For comparison with Meriones libycus auratus, see account of that subspecies. Remarks. The specimens from near Coefia and Benghazi are all immature, but in having distinct postauricular spots and slightly paler dorsal color, they suggest intergradation with M. 1. auratus to the south and west. An adult female, 325604, from 20 kilometers east of Tobruch is noticeably paler and more grayish in dorsal color and has a more reduced pencil than the two specimens from the type locality. In these characters, this specimen resembles neither typical M. l. libycus nor M. l. azizi, but because of its small cranial and body size and the geographic position of the collecting locality, it is here included with the latter subspecies. With the exception of a single specimen from near Maraua, this subspecies is known only from the Mediterranean littoral of northern Cyrenaica. In these coastal areas, members of this subspecies occur with Meriones caudatus, Jaculus orientalis, Jaculus deserti, Gerbillus eatoni, and several species of dipodil gerbils. RODENTS OF LIBYA 187 Genus Psammomys Cretzschmar In the past, the taxonomy of the genus Psammomys has been almost constantly in a state of confusion. Thomas (1902) was the first to report on representatives of this genus from Libya and described Psammomys tripolitanus as a new species based on specimens from Bou Cheifa, Wadi Aggar, and Wadi Cheggar of northern Tripolitania. He assigned specimens, which were much smaller in size and paler in color, from Bu Ngem and the Wadi Wagis, Tripolitania, to Psam- momys roudairei Lataste. The latter species was known from only two immature types (type specimen and cotype) and had previously been regarded by Lataste (1887) as a synonym of Psammomys obesus Cretzschmar. Many years later, Thomas (1925) after examining more specimens from near the type locality of P. roudairei in Algeria, once again placed P. roudairei in the synonymy of P. obesus and proposed the name Psammomys vexillaris for the small, pale-colored specimens from Bu Ngem and the Wadi Wagis in Libya. . Since that time, P. tripolitanus and P. vevillaris have been variously regarded as full species (de Beaux, 1932; Zavattari, 1934) or either one or the other regarded as subspecies of Psammomys obesus (Eller- man, 1941; Ellerman and Morrison-Scott, 1951; Toschi, 1954). Ellerman and Morrison-Scott, as well as Toschi, considered P. tri- politanus as beng synonymous with P. o. obesus and accorded P. verillaris only subspecific rank under this species. More recently Setzer (1957), after examining two specimens from near El Agheila and Gheminez, Cyrenaica, reinstated P. tripolitanus as a subspecies of P. obesus and regarded P. vexillaris as a full species, based upon a single specimen from Wadi Bey about 45 kilometers west of Bu Ngem, Tripolitania. He considered the two forms as specifically distinct on the basis of the following characters of the skull of P. vexilaris: Supraorbital bead absent, temporal ridges markedly reduced, and molars relatively as well as absolutely larger than in P. 0. obesus. In addition to the above characters established by Setzer, this specimen from near Bu Ngem differs strikingly from topotypes of Psammomys obesus obesus from the Nile Delta in its much smaller overall size, less robust and more gracile skull, proportionately larger suprameatal triangles, more ventrally inflated auditory bullae, and less developed parietal crests and postorbital processes. In color and external characters, P. vexillaris differs markedly in having a much shorter tail with a less extensive pencil, grayish rather than blackish pinnae, greater suffusion of white on venter, white rather than strongly buff-colored dorsal surfaces of hind feet, and much paler, more subdued, dorsal color. 188 U.S. NATIONAL MUSEUM BULLETIN 275 I was unsuccessful in obtaining additional specimens of P. verillaris, but after reexamination of the single specimen collected by Setzer from the Wadi Bey, its specific status is unequivocal in my opinion. Psammomys obesus Cretzschmar Psammomys obesus Cretzschmar, Riippell Atlas, 58, pl. 22, 1828 (near Alexandria, Egypt). GENERAL DISTRIBUTION OF SPECIES. Israel, Jordan, Saudi Arabia, Egypt, Sudan, Libya, and Algeria. DistripuTion IN Lisya. Coastal plain and littoral deserts of Cyrenaica and Tripolitania. The range in Libya is doubtless much wider than the few collecting records indicate. DISTRIBUTION OF THE SUBSPECIES IN LIBYA. Psammomys obesus obesus. CyrENAICA: Coastal plain of north- eastern Cyrenaica. Psammomys obesus tripolitanus. CyrenaicA and ‘TRIPOLITANIA: Coastal plain and littoral deserts of the Gulf of Sirte. PUBLISHED RECORDS IN Lisya. CyrEenaica: Bou Cheifa (Thomas, 1902 [Psammomys tripolitanus]); El Agheila (de Beaux, 1932 [Psam- be SBitt 2A Le KILOMETERS Psammomys obesus |. obesus 2. tripolitanus Psammomys vexillaris 3. vexillaris Ficure 41.—Distribution of Psammomys obesus and Psammomys vexillaris. RODENTS OF LIBYA 189 momys tripolitanus]); Zauia Mechili (de Beaux, 1938 [Psammomys tripolitanus]); TRrrpoLiranta: Wadi Aggar, Wadi Cheggar (Thomas, 1902 [Psammomys tripolitanus)]). Comparisons. Psammomys obesus can be readily distinguished from Psammomys verillaris by its darker color and greater size in all di- mensions. Remarks. Superficially, members of this genus resemble those of the genus Meriones but upon closer scrutiny can be easily identified by their plain, rather than distinctly grooved, upper incisors and generally heavier, more angular skulls. Furthermore, representatives of the genus Psammomys are primarily diurnal, whereas jirds (Meriones) tend to be almost exclusively nocturnal in their habits. Specimens of Psammomys obesus obesus from coastal Libya east of the Cyrenaican Plateau do not differ appreciably from those representing Psammomys obesus obesus from farther east in Egypt. The few specimens from the coastal plain along the Gulf of Sirte, however, differ significantly from representatives of P. 0. obesus from Egypt and are here referred to Psammomys obesus tripolitanus. EcoLoGicaAL OBSERVATIONS. In Libya, these large rodents are limited in distribution to a rather narrow belt of alluvial soils and abundant vegetation, which occurs along the coastal plain and occasionally farther inland in portions of the transitional deserts. At present, specimens are not available from the coastal plain of Tripolitania, but doubtless this species occurs here also. These rodents have a similar distribution in Egypt. All specimens I collected were from the more alluvial soils of the shoulders of the road. As presently understood, these animals are exclusively diurnal in their habits, emerging from their burrows shortly after dawn, remaining active somewhat irregularly throughout the day, and retiring to their burrows shortly after sunset. They dig large burrows with conspicuous, well-worn entrances, usually marked by piles of freshly deposited talus covered with seeds and bits of local plants. They seem to prefer the loose soils of the elevated roadbed or nearby large hillocks with a dense vegetative cover. Frequently, during the daytime, they are seen scurrying across the road or running about the mounds while foraging. Diurnal traplines were surprisingly ineffective and only rarely were fully adult animals caught. On one occasion east of Tobruch, these diurnal traps were left in position throughout the night and produced three jirds (Meriones). The occurrence of these jirds in the same trapline suggests that mem- bers of these two genera occur together in the same burrow complexes. The jirds, however, forage at night and the sand rats (Psammomys) feed only during the hours of daylight. 190 U.S. NATIONAL MUSEUM BULLETIN 275 Other species of rodents occurring in these more lush habitats of the Libyan coastal plain include Gerbillus henleyi, Gerbillus campestris, Gerbillus eatoni, Jaculus orientalis, Spalax ehrenbergi, and Gerbillus kawseri. Psammomys obesus obesus Cretzschmar Psammomys obesus Cretzschmar, Riippell Atlas, 58, pl. 22, 1828 (near Alexan- dria, Egypt). SPECIMENS EXAMINED. Sixteen, from Cyrenaica: 20 km E To- bruch, 13 (1 skin only); 5 km W Bardia, 3. M®EASUREMENTs. Averages and extremes of six adult females and the measurements of one adult male, 325646, from 20 kilometers east of Tobruch, are, respectively: Total length 285.8 (271-300), 288; length of tail 122.5 (110-128), 110; length of hind foot 35.2 (35-36), 38; length of ear 14.8 (14-17), 15; greatest length of skull 42.2 (40.4— 43.5), 40.5; length of auditory bulla 14.3 (13.5-14.6), 13.6; alveolar length of upper molariform toothrow 7 (6.5-7.6), 6.7; least inter- orbital breadth 6.7 (6.3-7), 6.8; length of nasals 16.3 (15.3-17.6), 16.3; breadth of rostrum at level of antorbital foramina 4.3 (4-4.6), 4.5; greatest breadth across zygomatic arches 24.9 (23.8-25.5), 23.6; least breadth between parietal ridges 10.9 (10.5-11.2), 10.5. Diagnosis. Pelage of dorsum dense and long but in old specimens heavily worn, particularly in middorsal region where denuded patches often disclose plumbeous-colored basal portions of hairs; sides varying from Pale Orange-Yellow to Light Orange-Yellow and flanks becoming darker in middorsal region approaching Ochraceous- Tawny; all parts of dorsum interspersed with brownish hairs; thus entire upperparts formed from a variety of colors and color patterns resulting in a pronounced variegated appearance; area between the ears and above the eyes, however, more uniformly colored Cinnamon or Ochraceous-Tawny; circumorbital areas Light Ochraceous-Buff heavily suffused with black; this color pattern extending anteriorly along the rostrum and posteriorly to the level of the ears; circumoral and mystacial areas and dorsal surfaces of fore and hind feet and legs ranging from Warm Buff to Antimony Yellow, the latter being more concentrated in the scapular regions, which appear more brightly colored than the surrounding pelage; ears relatively short, medial surface of pinna with uniform covering of buffy hairs; anterior margin of pinna with prominent row of rather stiff hairs, which project backward into inner surface of the pinna; vibrissae stiff and relatively short, formed of about equal numbers of black and buff-colored hairs; palmar surfaces of front feet naked and bearing distinct metacarpal tubercles; four primary digits (2-5) with evenly spaced transverse ridges and terminating in well-developed claws; first digit rudimentary without functional claw; plantar surfaces of hind feet with irregular RODENTS OF LIBYA 191 covering of hairs; all five digits well defined, sparsely haired, and all with functional claws; entire underparts strongly suffused with colors varying from Warm Buff and Ochraceous-Buff to Antimony Yellow; in all specimens an irregular whitish patch is present in the pectoral region; tail relatively short and same color as the dorsum except for some faint admixtures of brownish-colored hairs dorsally ; a prominent pencil, varying in color from Cinnamon-Brown to Prout’s Brown, occupying the distal one-fourth of the dorsal and ventral surfaces. Skull: Size relatively small for the genus but markedly angular and robust; zygomata extremely strong and heavy, and in older specimens, markedly bowed posteriorly; rostrum wide and heavy; anterior palatine foramina relatively short and broad; posterior palatine canals indistinct; molariform teeth heavy, grinding surfaces usually evenly worn; pterygoid processes heavy, with distinctly knobbed hamulae; auditory bulla small, not markedly inflated ventrally, but with greatly expanded meatal process, which almost touches squamous portion of temporal bone; suprameatal triangle conspicuous, usually completely enclosed by enveloping processes of temporal and supraoccipital bones; parietals with prominent lateral ridges extending from lambdoidal ridge to postorbital processes of frontal bone. Comparisons. The specimens from near Tobruch and Bardia, Cyrenaica, differ from representatives of Psammomys obesus nicolli Thomas from the Nile Delta and from those of Psammomys obesus terraesanctae Thomas from Palestine in being markedly smaller in all measurements. For comparisons of these specimens from Tobruch and Bardia with representatives of P. 0. tripolitanus, see account of that subspecies. Remarks. The specimens from Tobruch and Bardia are clearly referable to Psammomys obesus obesus. Except for their more brilliant yellowish-orange dorsal color and more worn-looking dorsal pelage, they are almost indistinguishable from specimens representing P. 0. obesus from Salum, El Alamein, and other coastal localities to the east. These differences in color are well within the expected range of indi- vidual variation within a given population. Setzer (1957) assigned specimens of P. obesus from El Alamein, Western Desert Governorate, Egypt, to P. 0. tripolitanus. In a later paper, Setzer (1963) regarded these specimens from western Egypt as intergrades between P. o. tripolitanus and P. 0. obesus but more closely related to the latter subspecies. The specimens from Tobruch and Bardia, Cyrenaica, in their slightly smaller size also suggest inter- gradation with P. 0. tripolitanus. It is doubtful that genetic exchange is common between populations of P. 0. tripolitanus and P. 0. obesus because of the reduction or absence of coastal plain in many parts of northern Cyrenaica. 192 U.S. NATIONAL MUSEUM BULLETIN 275 Psammomys obesus tripolitanus Thomas Psammomys tripolitanus Thomas, Proc. Zool. Soc. London, pt. 2, p. 9, 1902 (Bou Cheifa, on the coast, Cyrenaica, Libya). SPECIMENS EXAMINED. Six, from Cyrenaica: Gheminez, 1; 20 km SW Agedabia, 1; 10 km S Agedabia 3; 5 km W El Agheila, 1. MEASUREMENTS. Measurements of an adult female, 325630, from 20 kilometers southwest of Agedabia, are: Total length 300; length of tail 127; length of hind foot 34; length of ear 14; greatest length of skull 41.3; length of auditory bulla 14.7; alveolar length of upper molariform toothrow 7; least interorbital breadth 6.9; length of nasals 15.7; breadth of rostrum at level of antorbital foramina 4.5; greatest breadth across zygomatic arches 24.7; least breadth between parietal ridges 11. DiaGnosis. Same as for P. 0. obesus, except dorsum with stronger suffusion of brownish hairs, and skull smaller and more gracile. Comparisons. Compared to representatives of P. 0. obesus from near Tobruch and Bardia, Cyrenaica, and near topotypes of P. 0. obesus from Burg el Arab and El Daba, Western Desert Governorate, and Damanhur and Hofs, Beheira Province, Egypt, the few specimens from the coastal plain of the Gulf of Sirte are smaller in overall size of skull, have wider interorbital breadths, wider rostra, shorter anterior palatine foramina, and are darker in dorsal color. Because the range of P. 0. obesus is interposed between the ranges of P. o. tripolitanus and those of Psammomys obesus nicolli from the Nile Delta and Psammomys obesus terraesanctae from Palestine, critical comparison with the two latter subspecies was not undertaken, but from cursory examination both P. 0. nicolli and P. o. terraesanctae appear to be significantly larger both cranially and in external size and dimensions. Psammomys obesus nicolli is also darker in color, whereas P. o. terraesanctae is noticeably paler and more uniformly colored than P. o. tripolitanus. Remarks. Topotypes of P. o. tripolitanus are not available for study, but because the specimens from Gheminez and the vicinity of Agedabia agree closely with the description and measurements of P. 0. tripolitanus as given by Thomas (1902), and because of geographic proximity, they are here referred to this subspecies. Psammomys vexillaris vexillaris Thomas Psammomys vezxillaris Thomas, Ann. Mag. Nat. Hist., ser. 9, vol. 16, p. 198, July 1925 (Bondjem [= Bu Ngem], Tripolitania). GENERAL DISTRIBUTION OF SPECIES. Libya and Algeria. DistTriBuTION IN Lipya. At present, this species is known from only the vicinity of the type locality. The range probably includes most of the coastal plain and the transitional deserts of Tripolitania. RODENTS OF LIBYA 193 SPECIMENS EXAMINED. One, 302254, from the Wadi Bey, 45 km W Bu Ngem, Tripolitania, Libya. PUBLISHED RECORDS. TRIPOLITANIA: Bu Ngem, Wadi Wagis (Thomas, 1902 [Psammomys roudairei]). MEASUREMENTS. The measurements of an old male, 302254, from near Bu Ngem, are: Total length [224]; length of tail [93]; length of hind foot 32; length of ear 12; greatest length of skull 35; alveolar length of upper molariform toothrow 6.1; least interorbital breadth 6.2; length of nasals 13.1; least breadth between parietal ridges 9.5. Draenosis. Upperparts varied in color owing to suffusions of various shades of buff, gray, brown, yellow and orange; a broad, indistinct Pinkish Cinnamon band extending from the rostrum to the rump; fine guard hairs projecting beyond the underlying hairs on the dorsum; sides paler in color than dorsum and with greater admixture of dark hairs; preauricular and suborbital areas grading from Light Buff to Warm Brown and strongly suffused with brownish-black hairs; cir- cumoral and mystacial areas and region between chin and pectoral girdle white with moderate suffusion of Light Buff; postauricular patches indistinct, same color as surrounding pelage; pinnae of ears heavily furred with pale, Light Buff hairs, some of which partially cover inner aspects of pinnae. Vibrissae relatively short, formed from both black and white hairs, and extending posteriorly about 8 milli- meters beyond the ears; scapular areas more brilliantly colored than surrounding areas and appearing as vaguely defined patches of Warm Buff and Light Ochraceous-Buff; this same color imparted to the pectoral region below, but more subdued here; entire underparts predominantly white, but irregularly interspersed with patches of Light Buff, Pale Ochraceous-Buff, and Warm Buff; upperparts of front legs and dorsal surfaces of forefeet Light Buff; palmar surfaces almost naked; hind feet almost pure white dorsally; sparsely haired ventrally with conspicuous naked areas on proximal one-half of plantar surfaces; forelegs with five digits with claws, the first digit being almost rudimentary; hindlegs with five functional digits bearing well-devel- oped claws; tail relatively short, Warm Buff, and unicolorous except for a rather distinct pencil which occupies the distal one-fifth of the dorsal surface. Skull: Noticeably small and gracile; suprameatal triangles relatively large and completely enclosed by enveloping processes of the temporal and supraoccipital bones; auditory bullae large and inflated ventrally; postorbital processes and parietal crests poorly developed; anterior palatine foramina relatively long; molari- form teeth large and wide; supraorbital bead absent. Remarks. Originally, Thomas (1925) recognized two subspecies of Psammomys verillaris. The range of the nominate subspecies was thought to include the coastal and interior deserts of Tripolitania, 194 U.S. NATIONAL MUSEUM BULLETIN 275 Libya, and Psammomys vevillaris edusa, with type locality at Mil Mahases, Chegga, south of Biskra, Algeria, was believed to be confined to the Algerian Sahara. Ellerman and Morrison-Scott (1951) regarded P. v. edusa as a synonym of Psammomys obesus verxillaris, the species P. verillaris at the same time being relegated to subspecific rank under P. obesus. Psammomys verillaris is here accorded full specific rank, based primarily upon its smaller size, both cranially and in external dimensions, and upon additional characters as given by Thomas (1925), Setzer (1957), and the present author. Because I have examined no specimens from Algeria, I cannot comment on the status of P. v. edusa. In Libya, this small sand rat is known only from the type and type series as reported by Thomas (1925) and from a single old male, 302254, obtained in 1955 by Setzer from the Wadi Bey near the type locality. According to Setzer (1957), this animal was dug from its burrow which was located in an area of consolidated sand with sparse vegetation. My efforts to obtain additional specimens of this rare sand rat were to no avail. Family Spalacidae Genus Spalax Gildenstaedt Spalax ehrenbergi aegyptiacus Nehring Spalax aegyptiacus Nehring, 8. B. Ges. Nat. Fr., Berlin, p. 180, 1898 (Ramleh, near Alexandria, Egypt). GENERAL DISTRIBUTION OF SPECIES. Syria, Israel, Egypt, and Libya. DistRiBUTION IN Lrpya. Cyrenaican Plateau, including the Gebel Achdar and the coastal plain of Cyrenaica. SPECIMENS EXAMINED. Seven, from Cyrenaica: 5 km NW Labrag, 3; Wadi el Kuf, 13 km WSW Messa, 1;8 km N Benghazi, 1; 4 km S Agedabia, 1; 20 km SW Agedabia, 1. PuBLISHED RECORDS IN Lipya. Cyrenaica: Ras el Ferg (Sordelli, 1899); Barce (Ghigi, 1920); Benghazi (Zavattari, 1934; Toschi, 1951). MEASUREMENTS. Measurements of two adult females, 325655 and 325656, from 5 kilometers northwest of Labrag and the measure- ments of an adult female, 325652, from 20 kilometers southwest of Agedabia, are, respectively: Total length 172, 180, 190; length of tail 15, 15, 16; length of hind foot 21, 22, 23; length of ear 5, 5, 5; con- dyloincisive length of skull 38.5, 40.7, 39.9; crown length of upper molariform toothrow 7.4, 7, 7.1; palatilar length 21.8, 22.3, 22.8; length of anterior palatine foramina 2.9, 3.2, 3.2; greatest breadth across zygomatic arches 28.8, 29.3, 29.4; least interorbital breadth 6.9, 6.4, 6.7; length of nasals 16.6, 17.8, 17.8; breadth of rostrum at level of antorbital foramina 7.1, 6.9, 7.4; greatest length of skull RODENTS OF LIBYA 195 LIBYA o 9 1m a KILOMETERS Spalax ehrenbergi aegyptiacus Figure 42.—Distribution of Spalax ehrenbergi aegyptiacus. 41.2, 43.6, 42.8; length of diastema 14.2, 14.7, 15; basilar length of skull 34, 35.7, 35.2; greatest breadth of rostrum 7.5, 8, 8.1. Diaenosis. Most distinctive feature is the featureless, cylindrical body without a visible tail, and superficially appearing to lack eyes, ears and nostrils; rostrum furnished with a hardened and slightly enlarged cartilaginous plate beneath the skin and near the origin of the vibrissae, which presumably aids in pushing and moving dirt in the underground tunnels; vibrissae correspondingly small and fine in texture; pelage short, dense, and silky and of almost uniform color dorsally, varying in different specimens, however, among shades of Ochraceous-Tawny, Sayal Brown, and Buckthorn Brown, and ven- trally somewhat darker owing to less suffusion of these colors. In older specimens, pelage becoming worn and somewhat darker owing to greater exposure of the Plumbeous underfur; rostrum, in young specimens, light gray in color, but, in old specimens, rostral, auricular, and entire facial areas becoming a much darker gray; eyes not visible externally, but present as small rudimentary structures in the usual position in the orbit; pinnae of the ears, on close examination, present as inconspicuous cartilaginous rings which are obscured by the dense 196 U.S. NATIONAL MUSEUM BULLETIN 275 pelage; forefeet, bearing five digits with claws, remarkably small in view of the fossorial habits of these rodents; hind feet also relatively small and with five digits, but with larger claws; fore and hind feet approaching color of dorsum, but naked ventrally. Skull: Large, massive, and angular with conspicuous development of the lambdoidal and sagittal crests; shape of skull almost triangular in outline owing to the relatively small braincase, the abrupt anterior convergence of the zygomata and the relatively short and wide rostum; interorbital breadth markedly constricted; supraoccipital markedly expanded dorsally, with numerous inflated elevations, and directed a consider- able distance anteriorly; incisors extremely long, relatively narrow, and orange in color on their anterior faces; molariform teeth moderate in size with intricate interwoven patterns in the enamel and dentine, and with conspicuous styles on the lateral surfaces; infraorbital foramina large with corresponding reduction in size of the frontal plate of the premaxillae; dorsal margin of foramen magnum smoothly rounded; auditory bullae markedly reduced to thick, heavily ossified structures with prominent external meatal processes and conspicuous, attenuated styliform processes; anterior palatine foramina markedly reduced in size; palate with prominent midventral rib; posterior palatine canals small and inconspicuous; pterygoid processes heavy and with club-shaped hamulae; basioccipital broadly wedge-shaped. Remarks. Nehring (1897) regarded the mole rats of the Near East as representing several distinct species. He described Spalax ehrenbergi from Jaffa, Palestine, Spalax kirgisorum Nehring from northern Syria, Spalax intermedius Nehring from farther south in Syria, and named Spalax aegyptiacus Nehring with the type locality at Ramleh, near Alexandria, Egypt. Later, Mehely (1913) regarded all members of this group as one species and considered S. kirgisorum and S. aegyptiacus as varieties of Spalax ehrenbergi. Many years later, Ellerman (1941) elevated S. kirgisorum to full species status on the basis of page priority in the original description and relegated S. ehrenbergi and S. aegyptia- cus to subspecific rank, thus reversing the taxonomic status of S. ehrenbergi and S. kirgisorum. A short time later, Bate (1945) observed that, although the description of S. kirgisorum clearly preceded that of S. ehrenbergi, the latter form is given a prior place in illustrations of cheek teeth, and is followed by S. kirgisorum. She stated that in works published prior to 1931, figures are acceptable as valid descriptions, and therefore the name Spalax ehrenbergi should be regarded as ante- dating that of Spalax kirgisorum. More recently, Ellerman and Morrison-Scott (1951) consider S. ehrenbergi as a valid species but regard S. kirgisorum as a synonym of S. ehrenbergi ehrenbergi. Thus, the species S. ehrenbergi is currently composed of two subspecies, S. e. ehrenbergi and S. e. aegyptiacus. RODENTS OF LIBYA 197 Toschi (1954) assigned specimens from Ras el Ferg, Barce and Beng- hazi, Cyrenaica Province, Libya, to S. e. aegyptiacus. Although Setzer (1957) saw evidences of mole rats at Gheminez, Derna, Barce, and near Agedabia, he obtained no specimens. In the present study, I obtained seven specimens from four localities in Cyrenaica. Although they are from widely separated localities which differ rather sharply in characteristics of soil, vegetative cover, and climate, they are quite similar morphologically. They differ noticeably, however, from representatives of S. e. aegyptiacus from Burg el Arab, Western Desert Governorate, Egypt, in their smaller size of most ex- ternal and cranial measurements, narrower rostra, which are more constricted at the level of the infraorbital foramina, more delicate zygomata, broader frontal plates of the premaxillae, larger infraorbital foramina, smaller, narrower, and shorter incisors, and more smoothly rounded dorsal margin of the foramen magnum. In the specimens from Cyrenaica, the styliform process of the auditory bulla is more attenu- ated and projects farther medially, and the angular process of the mandible is smaller and more knobbed. The above differences would normally be sufficient to warrant con- sidering these Libyan mole rats as belonging to a distinct subspecies, but too few specimens are available for accurate designation. Further- more, they agree rather closely with the cranial measurements given for Spalax aegyptiacus in the original description. Despite the foregoing differences, I consider it best, until such time as additional specimens of mole rats are forthcoming, to refer all Libyan specimens to S. e. aegyptiacus. EcoLoGIcAL OBSERVATIONS. Mole rats are common on the coastal plain and uplands of the Cyrenaican Plateau and are relatively common farther south and west along the coastal plain of the eastern portion of the Gulf of Sirte. On the Cyrenaican Plateau and the Gebel Achdar, they seem to prefer loose soils at the margins and bottoms of the larger valleys and the more fertile soils of the higher tablelands. Mounds were also observed on the rocky slopes north of El Faidia near the highest point of the Cyrenaican Plateau. These rodents apparently attain the southwesternmost limits of distribution for the species on the coastal plain south and west of Agedabia. Currently they are unknown from the Tripolitanian coastal plain. Mole rats occur inland for varying distances, probably depending upon the amount of rainfall for a particular year. While en route to Gialo in the spring of 1962, we saw fresh diggings 25 kilometers inland from the Mediterranean coast. Setzer (in verbis) also attests to their presence in these inland localities. It is almost certain that they do not occur in or near the oases of the Saharan interior. 198 U.S. NATIONAL MUSEUM BULLETIN 275 These remarkable rodents plug the entrances to their burrows with soil, and they are rarely observed above ground. On several occasions, movements of the plug or fresh talus were observed during the day- time, indicating that they are active both day and night. Specimens were obtained with the use of Macabee gopher traps but only after exhaustive efforts because of the unusually hard, resistant nature of the soil. The small diameter of the entrance of the burrow, which was almost always difficult to locate, and the insistence of these mole rats on pushing fresh dirt over the trap, made trapping difficult. During the rainy season in the spring, the soils of the coastal plain are relatively soft and easily workable, and diggings of mole rats are widespread. Accordingly, traps can be more easily set, and the yield is greater. Later in the summer, after the soil has hardened, the number of active burrows is greatly reduced, and in some localities collecting mole rats is much more difficult, if not impossible. At this time these soils of the coastal plain become almost impervious. It is interesting to note that mole rats occupying the more firmly packed soils of the Cyrenaican Plateau are generally smaller than those living in the softer, more sandy soils of the coastal plain. Selec- tion has apparently favored smaller body size in these areas where digging is more difficult and a smaller diameter of the burrows is desirable. The soils of the Cyrenaican Plateau are probably harder and less sandy than those of the Egyptian littoral farther east, and this differential in hardness of the soil may account for the differences in size of mole rats from the two areas. The character of the soil seems to be the most critical factor in the distribution of these burrowing rodents, and vegetative cover and other physical features of the terrain are of secondary importance. One specimen, 325652, from near Agedabia was taken from a series of active burrows in the extremely hard-packed soil near the roadside on a grassy portion of the coastal plain. These grassy areas, most of which contained diggings, were interspersed among the rather dense, shrubby vegetative cover of the coastal plain. Another specimen, 325651, was obtained farther inland where the coastal plain is broad and featureless and has a more uniform vegetative cover. This speci- men was obtained during the spring when the recently emerged grasses were lush and green, and the soil, which normally would have been almost impervious, was soft and workable. Near Labrag, three specimens were obtained from the high uplands of the escarpment which forms the northern terminus of the Cyrenaican Plateau. Even though fresh diggings were widespread, the soil here was extremely hard and rocky, and the specimens were obtained only after laborious efforts. A single specimen, 325657, was obtained from the more alluvial soils in the bottom of the Wadi el Kuf where the ground was also nearly impervious. RODENTS OF LIBYA 199 According to Setzer (1957) and Hartert (1923), the local Arabs believe that because mole rats lack visible eyes and are apparently blind, anyone having contact with them will also become blind. Family Muridae Genus Rattus Fischer Rattus norvegicus (Berkenhout) Mus norvegicus Berkenhout, Outlines N. H. Great Britain and Ireland, vol. 1, p. 5 (Great Britain). Remarks. In Libya, the Norway rat is known only from Tripoli (Toschi, 1951), although it probably occurs in most, if not all, of the larger coastal cities and may occur in the wild state in the Cyrenaican Plateau. They are thought to be endemic to northern China and Manchuria. In recent centuries, they have been carried westward as a result of the increased development of western commerce. Their introduction into North Africa most likely was through the agency of shipborne rats in the major ports where ships frequently unloaded their produce. i a ae aa KILOMETERS Rattus norvegicus Ficure 43.—Known locality of occurrence of Rattus norvegicus. 200 U.S. NATIONAL MUSEUM BULLETIN 275 According to Rode (1948), the Norway rat is abundant in all ports of North Africa and occurs also in the large villages of the interior. It is doubtful that they occur in the Saharan interior of Libya. These rats are known to have a definite predilection for moist habitats and frequently inhabit stream banks where they demonstrate marked abilities for swimming and burrowing. Even in the tropics, they sur- vive only where the habitat has been significantly altered by man. Moist habitats in some of the larger oases of Cyrenaica and the Fezzan may provide the ecological requirements of these rats, but these areas are sporadic and localized. In addition, the barriers imposed by vast areas of desolate sand and arid desert must be sur- mounted before they could become established in these interior oases. In the present study, I collected extensively for several months in the interior oases and made frequent inquiries regarding the local rodent fauna. During this period I was unsuccessful in obtaining any rats (R. rattus or R. norvegicus) and observed no indications of their presence. Rattus rattus (Linnaeus) Mus rattus Linnaeus, Syst. Nat., 10th ed., vol. 1, p. 61 (Sweden). GENERAL DISTRIBUTION OF SPECIES. Nearly cosmopolitan owing to its commensal relationship with man; it is said to occur in the wild state in most of India, West Pakistan, Ceylon, foothills of the Hima- layan Mountains, Southern China, Burma, Thailand, Laos, Viet Nam, Malaya, and in the larger islands of the southwestern Pacific, including the Philippine Islands. DistrRIBUTION IN Lipya. Occurs commensally with man in the larger coastal cities of Benghazi, Tripoli, and Derna and apparently is present in the wild state in parts of coastal northern Cyrenaica. SPECIMENS EXAMINED. Four, from Cyrenatica: 27 km E Apollonia, 3; 12 km NW Gubba, 1. PUBLISHED RECORDS IN LispyA. Cyrenatca: Benghazi (Festa, 1925 [Epimys tectorum Savi]); Derna, Merg (=Barce) (de Beaux, 1938 (Rattus rattus nericola Cabrera]); TripouiTanta: Tripoli (Toschi, 1951 [Rattus rattus frugivorus Rafinesque)). MEASUREMENTS. Measurements of an adult female, 325658, from 27 kilometers east of Apollonia, are: Total length 343; length of tail 192; length of hind foot 33; length of ear 24; greatest length of skull 39.7; condylobasal length of skull 38.2; alveolar length of upper mo- lariform toothrow 6.9; greatest breadth across zygomatic arches 19; least interorbital breadth 5.5; length of nasals 14.5; length of audital portion of auditory bulla 7; palatal length 21.7; breadth of rostrum at level of antorbital foramina 4; length of anterior palatine foramina 7. Diacnosis. Upperparts varying among shades of Prout’s Brown, Snuff Brown and Sepia; a large portion of the hairs of the shoulders, RODENTS OF LIBYA 201 LIBYA ke? KILOMETERS Rattus rattus Ficure 44.—Distribution of Rattus rattus. Circle indicates specimens examined; triangles indicate published records. scapular areas, and back tipped with Cinnamon-Buff and appearing more lustrous than surrounding pelage; pale underparts contrasting markedly in color with that of the dorsum and varying from almost pure white in the region of the chin to Marguerite Yellow and Prim- rose Yellow in the midventral region, and becoming Light Buff laterally; vibrissae relatively long and formed entirely of black hairs; ears large, naked, thin, paper-like in texture and Olive-Brown in color; front feet relatively small, buff-colored above, naked below, and bearing four functional digits with short claws; hind feet pro- portionately larger than forefeet and with five functional digits rather than four, Light Buff above and naked below with a richly pigmented plantar surface bearing numerous prominent tubercles; tail long and attenuated, appreciably longer than the head and body, and covered throughout its entire length with short, stiff, inconspic- uous hairs which arise from between annular segments. Skull: Medium in size; gracile and narrow in outline; zygomata relatively delicate and bowing slightly laterad; braincase relatively flattened; auditory bullae small and moderately inflated ventrally; anterior palatine foramina long and wide; temporal ridges lyre-shaped; basioccipital broadly wedge-shaped. 285-134 O—68——14 202 U.S. NATIONAL MUSEUM BULLETIN 275 Comparisons. Rattus rattus can be distinguished from Rattus norvegicus by the following characters: Longer and more uniformly colored tail; one pair of postaxillary, pectoral mammae, rather than two pairs; smaller front feet; lyre-shaped temporal ridges, as opposed to parallel temporal ridges; first molar lacking the small accessory cusp, the latter being present in R. norvegicus. Remarks. Earlier workers in the systematics of rodents have applied subspecific names to the three common color types of the commensal or black rat (Rattus rattus). These color types are charac- terized as: black or gray above and below; brown above and dark gray below; brown above and white below; and correspond, respec- tively, to the subspecies R. r. rattus (Linnaeus), R. r. alerandrinus (Geoffroy), and R. r. frugivorus (Rafinesque). In the past, the com- mensal rats of the larger coastal towns of Libya have been variously assigned to one or more of these subspecies. More recently, ecological, behavioral, and genetic studies indicate that these so-called subspecies do not conform to the modern concept of subspecies and accordingly should be regarded only as color phases or genetic variants within the species. Caslick (1955), in an attempt to resolve some of the relationships of these color types in Rattus rattus, conducted a series of selective matings of wild-trapped black rats of mixed origin, and although, in color, the litter mates satisfied the requirements of subspecies and “unclassifiable intergrades” were of rare occurrence, he concluded that the current forms of R. rattus were best regarded as color phases within the species. Setzer (1952) also recognized these same three color types in commensal rats from the Nile Delta and noted that specimens from a given locality segregated out as the three expected color types plus intermediate forms. These intermediate forms, to which he attributed a single gene character for melanism, were suggestive of intergrades, but the presence of three distinct subspecies occupying the same en- vironmental niche (or geographic area) was clearly untenable. Other workers have frequently reported black rats of different color phases sharing the same habitat, and the individuals in a given population that did not conform to one of the so-called subspecies were considered intergrades. Johnson (1946) commented on a litter from the same nest that con- tained representatives of both the white-bellied and black-bellied color phases and stated that these color phases had no morphological distinctions, except those of color, and that the ecological differences mentioned by other workers were not evident in the population that he studied. Caslick (1955) suggests that the color phases of the commensal rat, recognized as the subspecies R. r. rattus, R. r. alerandrinus, and R. r. RODENTS OF LIBYA 203 frugivorus, may be similar to the well-known color phases of the black bear, red fox, and the gray and fox squirrels. No differences have been observed in the habits, movements, and survival differential of R. r. rattus and R. r. alexandrinus, although R. r. frugivorus has been considered by some to represent a ‘‘wild form”’ which frequently occurs in the feral state in fields and agricultural areas. In many cities and villages of Europe, North America, and North Africa, all three of these color types occur together. In my opinion, the recognition of rattus, alerandrinus, and frugivorus as subspecies of R. rattus is of doubtful utility, and I prefer to regard these so-called subspecies as merely color phases or phenotypic variants within this widely ranging species. If one subscribes to the older system of applying subspecific names to the commensal rats of Europe and North Africa, the four specimens from Cyrenaica clearly represent R. r. frugivorus. The four specimens from Cyrenaica were trapped in the lush vegetation bordering small permanent streams. The collecting site near Gubba is located in a deep canyon of the coastal escarpment and several kilometers from the nearest human habitation, whereas the specimens from near Apollonia were taken from an elevated portion of the coastal plain in traps set only a few hundred meters distant from human dwellings. These specimens from Cyrenaica constitute the first records of R. rattus occurring in the wild state in Libya. They are unknown from the oases of the interior. Genus Mus Linnaeus Mus musculus Linnaeus Mus musculus Linnaeus, Syst. Nat., 10th ed., vol. 1, p. 62, 1758 (Upsala, Sweden). GENERAL DISTRIBUTION OF SPECIES. Cosmopolitan as a result of introduction by man. DISTRIBUTION IN LiByA. Occurs as a commensal with man in the larger coastal cities and villages of the interior and is quite widely distributed in the wild state. SPECIMENS EXAMINED. One hundred fifty-eight, from CyrEeNatica: 27 km E Apollonia, 11; 11 km SW Susa (=Apollonia), 3; 5 km NW Labrag, 6; 12 km NW Gubba, 2; Cyrene, 1; 3 km E Derna, 2; 35 km W Messa, 1; 10 km SW El Faidia, 3; 7 km E Maraua, 1; 5 km W Tocra, 49 (1 skin only); 20 km SW Tocra, 3; Giarabub, 2; El Hauuari, Cufra Oasis, 1; El] Giof, Cufra Oasis, 12; from TRrrIpoLITANIA: 5 km W Cussabat, 3; 12 km S Chicla, 2; 7 km S El Gheddahia, 1; 20 km E Sirte, 1 (skin only); from Frzzan: Brach, 37 (10 skull only) ; Sebha, 1; Goddua, 11 (7 skull only, 2 skin only) ; Meseguin, 2; Traghen, 1; 28 km E Murzuch, 1; Murzuch, 1. 204. U.S. NATIONAL MUSEUM BULLETIN 275 LIBYA KILOMETERS \ Ml { Swan kK | s, | | | Ng ae ae Noo Mus musculus Ficure 45.—Distribution of Mus musculus. Circles indicate specimens examined; triangle indicates published record. PUBLISHED RECORDS IN Lisya. Cyrenatca: Benghazi, Derna (Klap- tocz, 1909 [Mus musculus orientalis Cretzschmar]); Benghazi, Ghe- minez (Festa, 1921 [Mus musculus gentilis Brants]); Benghazi (Har- tert, 1923); Giarabub (de Beaux, 1928 [Mus musculus musculus and M. m. orientalis|); Augila, Cufra and Gialo (de Beaux, 1932 [M. m. orientalis]); Derna, Wadi el Kuf (MM. m. orientalis) and Merg (Mus musculus brevirostris) (de Beaux, 1938); TrrpotrraAniaA: Tarhuna (Thomas, 1902 [M. m. orientalis]); Tripoli (Klaptocz, 1909 [M. m. orventalis]); Frzzan: Idri, Murzuch (Toschi, 1951 [M. m. gentilrs]). MEeEaAsuREMENTs. Averages and extremes of 17 males and 8 females from Brach, Fezzan Province, are, respectively: Total length 164.1 (149-182), 158.6 (156-163); length of tail 82.9 (76-90), 78.3 (75-81); length of hind foot 19 (18-20), 18.8 (18-19); length of ear 16.6 (14- 21), 15.4 (14-20); greatest length of skull 22 (20.7-23.2), 21.3 (20.7— 22.2); condyloincisive length of skull 21.1 (19.6—22.2), 20.4 (19.8- 21.3); crown length of upper molariform toothrow 3.7 (3.3-4), 3.7 (3.6-3.9); greatest breadth across zygomatic arches 11.5 (10.9-11.9), 11.3 (10.9-11.6); least interorbital breadth 3.6 (3.5-3.8), 3.7 (3.5-3.8) ; length of nasals 8.2 (7.5-8.6), 7.8 (7.1-8.4). RODENTS OF LIBYA 205 Diacnosis. Two distinct color types of Mus musculus occur in Libya, a light-bellied form and a dark-bellied form. In the light- bellied form, the hairs of the venter are either white throughout or white distally with plumbeous bases. The dark-bellied form has gray or brown-tipped hairs on the venter, which are always plumbeous basally. The color of the dorsal and ventral pelage is markedly con- trasting in the white-bellied form, whereas, in the dark-bellied form, the color of both surfaces is quite similar. The two forms differ ap- preciably in the color of the dorsum, that of the dark-bellied form being markedly and more uniformly darker (ranging from Saccardo’s Umber to Sepia); in the light-bellied form, it is more variable and ranges from Clay Color to Olive Brown and frequently is variegated owing to suffusions of gray and buff. The dorsal surfaces of the hind feet are dusky or gray in the dark-bellied form, whereas they are almost white in the light-bellied form. In both forms, the tails are naked except for a scanty covering of inconspicouus whitish hairs. Cranially, the two types do not differ significantly and both have extremely small, gracile skulls with flattened braincases, short rostra (more pronounced in the white-bellied form), large anterior palatine foramina, small posterior palatine canals, relatively small cheek teeth, broad basioccipitals, and small, bulbous auditory bullae. The “Mus notch” is pronounced on the upper incisors. Remarks. The systematic status of the house mouse (Mus musculus) has never been firmly established. The principal effort to resolve the nomenclatural relationships of Mus musculus is that of Schwarz and Schwarz (1943), who considered the wild species, Mus musculus, to originally consist of four subspecies, M. m. wagneri Eversmann, M. m. spicilegus Petényi, M. m. manchu Thomas, and M. m. spretus Lataste. According to the above authors, these wild forms (except for M. m. spretus, which occurs exclusively in the wild state) have given rise to the various commensal forms of the house mouse throughout the world. Schwarz and Schwarz contend that most of these commensal] forms, except those of western Europe, Russia, and Japan, have been derived from M. m. wagneri, which developed both an eastern and western series of commensals. The commensal Mus musculus of Libya supposedly arose from the western component of M. m. wagneri, which had its origin in southwestern Persia (= Iran) and from which it spread, by the agency of man and cultivation, through Iraq, Turkey, Syria, Israel, the Nile Valley, and westward across North Africa. From Africa these commensal forms have reached Italy, Spain, and western Europe. Throughout most of their range, depending upon the degree of specialization, these commensals form two types, a more specialized “commensal” from and a more generalized “wild”? form. The com- 206 U.S. NATIONAL MUSEUM BULLETIN 275 mensal form, according to Schwarz and Schwarz, has evolved along specific lines in response to 1is more intimate association with man and normally has a longer tail (frequently longer than the length of the head and body), a darker (more grayish) venter, richer (darker) shades of color dorsally, a shorter face, and smaller molariform teeth. In the wild form, the tail is shorter (always shorter than the length of the head and body), the venter is white, rather than gray, and forms a sharper contrast with the color of the pelage of the sides and flanks. These authors contend that, in many areas, both indoor and outdoor types of house mice are found. The outdoor (feral) types may represent either wild or commensal types, which are less specialized than the indoor types. The house mice of Libya, according to Schwarz and Schwarz, are represented by two subspecies, M. m. praetextus Brants and M. m. brevirostris Waterhouse, representing, respectively, the wild and commensal forms. Toschi (1954, pp. 264-265) summarized the work of all previous workers on Libyan mammals and listed four subspecies of Mus mus- culus as occurring in Libya. These included M. m. musculus, M. m. brevirostris, M. m. gentilis (=M. m. praeteztus), and M. m. orientalis. Both M. m. gentilis and M. m. musculus were listed from Benghazi and apparently represented, respectively, the feral and commensal forms of M. musculus. These subspecies mentioned by Toschi were based on specimens from widley scattered localities in Libya, and many were assigned to a given subspecies without regard to distribu- tional or taxonomic concepts. In the present study, many more specimens are available from widely scattered localities in Libya, and two distinct color types are discernible. Those from all interior localities represent the light-bellied form and are white ventrally with the individual hairs white through- out or plumbeous-colored basally. Dorsally, the coloration varies from extremely pale individuals to quite dark-colored forms. In all specimens from the interior of Libya, the dorsum and venter are markedly contrasted in color. Specimens from the coastal plain near Tocra in Cyrenaica typify the dark-bellied form in which the venter is gray or brown and thus not contrasting with the color of the dorsum. Light-bellied individuals also occur near Tocra but are less abundant. Setzer (1957) obtained both feral and commensal house mice in Libya and was able easily to distinguish two types on the basis of their dorsal and ventral coloration. He found, based on color, that the commensal kind agreed with the description of the feral form given by Schwarz and Schwarz, and that the feral kind agreed with the description of the commensal form as given by the above authors. He further stated that these color types did not represent subspecies as understood by modern taxonomists. RODENTS OF LIBYA 207 All Libyan specimens I collected were taken in the wild or feral state and, except for those from the Cyrenaican coastal plain, conform in the pattern of their coloration to the wild form M. m. praeteztus as established by Schwarz and Schwarz. The dark-bellied specimens from the coastal plain clearly represent the commensal form, M. m. brevirostris. These coastal specimens have shorter rostra than those from other localities, which is a character used by Schwarz and Schwarz to separate M. m. brevirostris from M. m. praetextus, but they lack the long tail which is reputed to be a character of the commensal form. Furthermore, both color types occur together on the coastal plain near Tocra, and neither show commensal tendencies. To me, these different color types are only color variants of the same subspecies. On the coastal plain near Tocra, and doubtless in many other localities in Libya, both color types (or subspecies) occur together; this clearly violates the concept that ‘“‘no two subspecies occupy the same geographic range.”’ For these reasons, I prefer to assign all of these mice occurring in Libya to the species Mus musculus and suggest that the different color types be interpreted as various stages in commensalism rather than as distinct subspecies as used in the context of modern taxonomists. EcoLoGIcAL OBSERVATIONS. In Libya, house mice are widely distributed and occur in a wide variety of habitats. Frequently, they act as strict commensals sharing the same dwellings as the local people. At some localities, they inhabit gardens and palm groves of the larger villages and oases. In many areas, they exist in the wild or feral state, completely divorced from the nearest influence of man. The largest series were taken on the coastal plain or from the larger interior oases. At Brach, in the Fezzan, house mice are abundant in the interior of the oasis where slightly elevated patches of Phrag- mites are interspersed among areas of open water. They are common inhabitants of the dense pockets of sedges and other mesophytic plants that encircle the saline lakes at El Giof and El Hauuari at Cufra Oasis. On the coastal plain near Tocra, Cyrenaica, a large series was taken from the dense, brush-covered coastal plain near the sea. In other parts of Cyrenaica, they occur in the dense, meso- phytic plant cover bordering small permanent streams or inhabit localized mesic pockets in the coastal escarpment. They were occa- sionally trapped in the chaparral vegetation of the higher portions of the Cyrenaican Plateau. Relatively high humidity, mesic conditions, and dense plant cover are the features common to all the above habitats. Only rarely are these commensal mice taken from dry situations, and they never inhabit soils formed exclusively of sand. Perhaps these dry habitats are marginal and the collection of house mice from them was entirely fortuitous. 208 U.S. NATIONAL MUSEUM BULLETIN 275 It is interesting to note that apparently house mice are absent from several of the large oases of southern Cyrenaica, such as Tazerbo and Bzema. Suitable habitat occurs in these isolated oases, but, unlike Cufra Oasis, they are far removed from the caravan routes and have relatively few outside visitors; thus, the introduction of commensals has probably never taken place. Genus Acomys Geoffroy Acomys cahirinus viator Thomas Acomys viator Thomas, Proc. Zool. Soc. London, pt. 2, p. 10, 1902 (Wadi Sultan, near Socna, Tripolitania, Libya). GENERAL DISTRIBUTION OF SPECIES. Libya, Egypt, and Algeria, and range probably includes additional countries and provinces of the Sahara. DisTRIBUTION IN Lipya. This species is known from only the type locality near Socna, Tripolitania Province, and from the oases of El Barcat, Fezzan Province, and El Giof (Cufra Oasis), Cyrenaica Province. LIBYA Li? KILOMETERS Acomys cahirinus viator Ficure 46.—Distribution of Acomys cahirinus otator. RODENTS OF LIBYA 209 SPECIMENS EXAMINED. Twenty-three, from Cyrenatica: El Giof, Cufra Oasis, 19; from TripouirantA: 5 km S Socna, 1; Bir Fergian, 10 km S Soena, 1 (skin only); from Frzzan: El Barcat, 2. MEASUREMENTS. Averages and extremes of 7 adult males and 10 adult females from El Giof, Cufra Oasis, are, respectively: Total length 202 (195-209), 203.1 (185-229); length of tail 104.3 (100-107), 104.3 (99-115); length of hind foot 19.4 (19-20), 19.4 (19-20); length of ear 19.6 (19-20), 19 (19-19); greatest length of skull 29.3 (28.4- 30.1), 28.7 (27.3-30); condyloincisive length of skull 27.3 (26.7-28), 26.5 (25-27.6); crown length of upper molariform toothrow 4.2 (4.1- 4.3), 4.2 (4-4.5); breadth of rostrum at level of antorbital foramina 3.2 (3.1-3.3), 3.2 (3.1-3.3); least interorbital breadth 4.8 (4.7-5), 4.8 (4.6-5); greatest breadth across zygomatic arches 14.4 (14-14.9), 14 (13.38-14.7) ; median length of nasals 10.5 (10.1—10.8), 10.3 (9.7—-10.6). Diacnosis. Upperparts ranging from Smoke Gray on scapular areas and sides to Deep Grayish Olive on middorsal region and rump; pelage of rump coarse and hispid owing to individual hairs modified into stiff bristles and spines; total dorsum mildly suffused with tones of Light Drab; base of pinna surrounded by band of distinct buffy- gray hairs; pinna large, sparsely haired, and ranging in color from Deep Grayish Olive to Dark Grayish Olive; chin, mystacial, and circumoral areas, forelegs, hindlegs, dorsal surfaces of fore and hind feet, and entire underparts pure white; ventral surfaces of fore and hind feet naked, with distinct palmar and plantar pads, and bearing five digits with claws; vibrissae relatively long, fine in texture, and formed largely of grayish hairs; tail fusiform, conspicuously bi- colored, Clove Brown above and Deep Olive-Buff below, and composed throughout its entire length of successive, imbricated segments, from the bases of which arise short, stiff, white hairs. Skull: Medium in size; parietals slightly expanded dorsally; anterior palatine foramina long and wide; molariform teeth relatively small and toothrow short; pterygoid fossae broad and long and with prominent elliptical fo- ramina on laterocaudal margins; auditory bullae small and noticeably inflated ventrally; pterygoid processes convergent anteriorly and forming a distinct rib separating the halves of the pterygoid fossae and extending to the level of the palate. Comparisons. From specimens representing