Zoology \! W ^Mv'll S NO V^/ A Review of the (ienera Crunomys and Archboldomys (Rodentia: Muridae: Murinae), with Descriptions of Two New Species from the Philippines l'!iic A. Rirkart Lawrence K. Ileanev lilas R. ral)aran/a, Jr Daiiilo S. Kali It ri)hlK;i(i(»i) I4M4 m iujs}ii;i)in' iii ldmi s! i ak m \ w \ irw iii^ FIELDIANA Zoology NEW SERIES. NO. 89 JUL 1 0 1998 FIELD MUSEUM LIBRARY A Review of the Genera Crunomys and Archboldomys (Rodentia: Muridae: Murinae), with Descriptions of Two New Species from the PhiUppines Eric A. Rickart Ulah Museum of Natural History- University of Utah Salt Lake Cit\. Ulah H4I 12 USA Bias R. Tabaranza, Jr. Department of Biology /lii;an Institute of Technolofiy lliiian City Lanao del Norte. Philippines Accepted September 5, 1998 Published June 30, 1998 Publication 1494 Lawrence R. Heaney Department of Zooloify Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago. Illinois 60605-2496 USA Danilo S. Balete Department of Zoology Field Museum of Natural Histmy Roosevelt Road at Lake Shore Drive Chicago. Illinois 60605-2496 USA Present address: NORDFCO 320 Fagle Court Condominiums 26 Matalino Street Diliman. Quezon City. Philippines PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1998 Field Museum of Natural History ISSN 0015-0754 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents Abstract 1 Introduction 1 Specimens Examined and Methods 1 Synopsis of Genera and Species 2 Crunomys Thomas, 1 898 2 C nmomy s fallax Thoma?,. 1898 6 Crunomys celebensis Musser. 1982 6 Crunomys melanius Thomas. 1907 6 Crunomys suncoides, new species 8 Archboldomys Mussen 1982 16 Archboldomys luzonensis Musser. 1982 16 Archboldomys musseri. new species 17 DiSCLSSK )N 22 Phylogenetic Relationships 22 Biogeography and Ecology 23 Acknowledgments 23 Literature Cited 24 5. Cranium and left mandible of Cruno- mys suncoides (fmnh 147942. holo- type) 12 6. Squamosal, bullar. and mastoid regions of Crunomys suncoides and Archboldo- mys tnusseri 13 7. Pterygoid region of Crunomys suncoi- des and Archboldomys musseri 14 8. Left molar toothrows of Crunomys suncoides and Archboldomys musseri .... 15 9. Karyotypes of Crunomys suncoides and A rchboldomys luzonensis 16 10. Adult male Archboldomys musseri (FMNH 147176. holotype) 17 11. Ratio diagram comparing Archboldo- mys musseri to A. luzonensis 18 12. Palatal regions oi Archboldomys mus- seri and A. luzonensis 19 13. Cranium and right mandible oi Arch- boldomys musseri (fmnh 147176. holo- type) 20 List of Illustrations 1 . Map of the Philippines with collecting localities 3 2. Adult male Crunomys suncoides (fmnh 147942. holotype) 9 3. Ratio diagram comparing Crunomys suncoides to C melanius 10 4. Palatal regions of Crunomys suncoides dead C melanius 11 List of Tables 1 . Measurements and other data from speci- mens of Crunomys and Archboldomys 4 2. Proportional relationships for selected measurements of Crunomys and Archbol- domys 7 A Review of the Genera Crunomys and Archboldomys (Rodentia: Muridae: Murinae), with Descriptions of Two New Species from the PhiHppines Eric A. Rickart Lawrence R. Heaney Bias R. Tabaranza, Jr. Danilo S. Balete Abstract The murine genera Crunomys and Archboldomys include species native to the oceanic Phil- ippines and Sulawesi. Recent surveys in the Philippines have yielded additional specimens that help clarify generic definitions and species limits. These include examples of a new species of Crimomys from north-central Mindanao Island and a new Archboldomys from northeastern Luzon Island. Members of both genera are relatively small, ground-dwelling rodents that ap- parently are diurnal and insectivorous. There are important external, cranial, and chromosomal differences between the genera, and they share few derived traits that unite them as a group separate from other Philippine murids. Most of their morphological similarities may reflect either convergence or retention of primitive traits. Archboldomys is restricted to high-elevation forests on Luzon Island, whereas Crunomys is distinctive in having a broad distribution that includes much of the Philippines as well as Sulawesi. Most species of Crunomys occur at low elevations, and this may promote broader geographic distribution by facilitating dispersal across intermittent land bridges or by increasing the likelihood of rafting. Introduction A century ago, the genus Crunomys was de- scribed by Oldfield Thomas on the basis of a sin- gle specimen from northern Luzon Island (Tho- mas, 1898). When Guy Musser reviewed the ge- nus Crunomys eight decades later, the number of specimens had increased only to seven; an addi- tional specimen served as the basis for his de- scription of the related Philippine genus Archbol- domys (Musser, 1982). The "shrew-mice" of these genera are among the most elusive and in- triguing members of the amazingly diverse murid fauna of the Philippine archipelago (Musser & Heaney, 1992; Heaney et al., 1997). Our recent field studies in the Philippines (Rickart et al., 1991; Heaney et al., 1997) have produced addi- tional specimens of Crunomys and Archboldomys that serve as the basis for this report. These ad- ditional specimens help clarify generic definitions and species boundaries, and illuminate ecological traits and biogeographic patterns. Included among them are examples of two species new to the Phil- ippine fauna, which we describe herein. Specimens Examined and Methods Specimens included in this study are deposited at the American Museum of Natural History, New York (amnh); Natural History Museum, London (BMNH); Delaware Museum of Natural History, Greenville (dmnh); Field Museum of Natural His- tory, Chicago (1-mnh); Mindanao State Universi- ty-IIigan Institute of Technology, Museum of Natural Sciences (msu-iit); Philippine National Museum, Manila (pnm); and National Museum of Natural History, Smithsonian Institution, Wash- ington, D.C. (USNM). The following samples were examined: Crunomys melanius — CAMIGUIN: Camiguin Province, Mt. Timpoong, 2 km N, 6.5 FIELDIANA: ZOOLOGY, N.S., NO. 89, JUNE 30, 1998, PP. 1-24 km W Mahinog. 1275 m (fmnh 154861. 154862); Kital-is. Sagay Municipality, 6.5 km W Mahinog, 900-1 100 m (MSI -IIT, two specimens); 0.5 km N. 6.5 km W Mahinog, 1000-1300 m (msl-iit, one specimen); LEYTE: Leyte Province, Mt. Lobi Range (dmnh 4222, holotype of Cnmomys ra- hori): MINDANAO: Bukidnon Province, Mt. Ka- tanglad Range, 17 km S. 7 km E Baungon, 1550 m (FMNH 147105, 147106); Cmnomys n. sp. — ho- lotype from MINDANAO: Bukidnon Province, Mt. Katanglad Range (see below); Archboldomys luzonensis — LUZON: Camarines Sur Province, Mt. Isarog (fmnh 95122, 147172, 147173; lsnm 573834-573840); Archboldomys n. sp.— holotype and specimen in pn.m from LUZON: Cagayan Province. Mt. Cetaceo. (see below). Published descriptions of Cnmomys fallax (Thomas. 1898; Musser. 1982) were augmented with information from recent photographs of the skin and skull of the holotype provided by P. Jen- kins. Measurements and other information for specimens of Cnmomys celebensis and additional specimens of C. mekmius at amnh and bmnh are from Musser (1982). Measurements of total length (TOT), length of tail (LT). length of hind foot including claws (LHF), length of ear from notch (LE). and body mass (WT) were taken from original notes of col- lectors or from previous publications. Tail, hind foot, and ear lengths were measured directly for some specimens preserved in fluid. The length of head and body (LHB) was determined by sub- tracting length of tail from total length. The num- ber of scale rings per centimeter (TSR) was count- ed at a point on the tail one-third the distance from the base, and the thickness of pelage was determined by measuring the total length of bunched hairs (LOF) in the mid-dorsal region. The following cranial and dental measurements of adult specimens were made to the nearest 0. 1 mm using dial calipers or a dissecting microscope and ocular micrometer, with limits as defined by Musser (1979, 1982): greatest length of skull (GLS), interorbital breadth (IB), zygomatic breadth (ZB), breadth of braincase (BBC), height of braincase (HBC), length of nasal bones (LN), length of rostrum (LR). breadth of rostrum (BR), breadth of zygomatic plate (BZP), breadth across incisor tips (BIT), length of diastema (LD), palatal length (PL), postpalatal length (PPL), length of incisive foramina (LIE), breadth of incisive fo- ramina (BIF), distance from incisive foramina to Ml (IF-Ml), length of palatal bridge (LPB), breadth of palatal bridge at Ml (PBMl), breadth of palatal bridge at M3 (PBM3), breadth of meso- pterygoid fossa (BMF). length of auditory bulla (LB), height of auditory bulla (HB), alveolar length of maxillary molar row (LMl-3). crown length of Ml (LMl), crown breadth of Ml (BMl), length of mandible and incisor (LMI), length of mandible (LM). height of mandible (HM). length of mandibular toothrow (Lml-3). Molar cusp terminology follows Musser and Hea- ney (1992). For some specimens, karyotypes were prepared from bone marrow cells. Live-trapped animals were processed following the methods of Rickart et al. (1989). Freshly killed animals caught in snap traps were processed with a modified method involving in vitro incubation of cells in an isoton- ic colchicine solution followed by hypotonic treat- ment and fixation. Fixed cell suspensions were frozen in liquid nitrogen in the field, and standard karyotypes were prepared in the laboratory after storage at -70°C for several months. Chromo- some terminology follows Rickart and Musser (1993). Synopsis of Genera and Species Crunomys Thomas, 1898 Type Species — Cnmomys fallax Thomas (1898: 394) Diagnosis — A genus of murine rodent distin- guished by the following combination of charac- ters: (1) small to moderate body size with a tail shorter than the combined length of head and body; (2) hind feet long and narrow with reduced first and fifth digits, and six plantar pads that are very small in relation to the entire plantai- surface; (3) pelage short and thick, hair texture varying from soft to spiny; (4) patterned coloration, darkest on the muzzle, top of the head, mid-dor- sally, on the rump, and on the dorsal surface of the legs, paler on the sides of the body, and much paler ventrally; (5) auditory bulla widely separat- ed from the squamosal and alisphenoid by the en- larged and coalesced postglenoid vacuity and postalar fissure; (6) a pattern of cephalic arterial circulation characterized by the absence or ex- treme reduction of the stapedial foramen and ar- tery and a secondary connection between the in- ternal carotid and orbitomaxillary circulation; (7) loss or extreme reduction of cusp t3 on the first and second upper molars; (8) cusp t9 coalesced FIELDIANA: ZOOLOGY ■'122° a 126° PHILIPPINES -18' - 10* - 6° 200 km 14°- 0 0 r- f^:' Leyte Camiguin 10°- 6°- 122° 126° Fig. 1. 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S±x RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS with central cusp t8 on first upper molar and lost on second upper molar; (9) upper and lower third molars small relative to other molars and with a reduced number of cusps; (10) fusion of the an- teroconid. metaconid. and protoconid of the first lower molar, together forming more than half of the occlusal surface (Musser, 1982; Musser & Heaney. 1992). Cnmoiuys is most similar to the endemic Philippine genus Archboldottiys. Detailed species comparisons are given by Musser (1982) and below under the descriptions of the new spe- cies. CoNTHNT AND Di.STRiBLTioN — As Currently un- derstood, the genus Cnmomys contains four spe- cies distributed in the oceanic Philippines (Ca- miguin. Leyte. Luzon, and Mindanao islands) and in Central Sulawesi, Indonesia. Crunomys fallax Thomas, 1898 Isabela shrew-mouse Remarks — The genus Crunomys and the type species C. fallax were described from a single adult specimen collected in Isabela Province in northeastern Luzon (Fig. 1 ). The holotype remains the sole example of the species. It is a compara- tively small murine rodent (Table 1 ). with a bi- colored tail that is substantially shorter than the combined head and body length (Table 2). The pelage is harsh and spiny, grayish brown tinted with yellowish buff dorsally. darkest along the midline, paler at the sides, and pale gray ventrally. The specimen was shot during the day, along a stream at an elevation of 1000 ft (300 m) in "parched-up" (seasonally dry?) lowland forest (Thomas, 1898; Musser, 1982). Crunomys celebensis Musser, 1982 Sulawesi shrew-mouse Rkmarks — This species was described by Mus- ser (1982) on the basis of three adult specimens collected in Sulawesi in 1974. It is the only mem- ber of the genus known to occur outside of the Philippines. Crunomys celebensis is larger than C. fallax and slightly smaller than adult C. melanius (Table 1). Color is similar to that of C. melanius; it is substantially darker than C. fallax, with less contrast between dorsal and ventral color and without a bicolored pattern on the tail. In contrast to both C. fallax and C. melanius. the pelage tex- ture is soft rather than harsh or spiny. There are several distinctive cranial and dental features, in- cluding: prominent mastoid and maxillary fenes- trae, a long and narrow palate, broad incisors, and relatively small molars (Tables 1. 2; Musser. 1982). The three specimens were trapped on or near the ground in streamside habitat, at mid-el- evations between 2700 and 3500 ft. (820-1070 m) in lowland evergreen tropical rainforest. Two were captured at mid-morning, suggesting that the species is diurnal. Nothing is known of the food habits (Musser, 1982). Crunomys melanius Thomas, 1907 Southern Philippine shrew-mouse Synonym — Crunomys rabori Musser, 1982 Remarks — Crunomys melanius was described by Thomas (1907) on the basis of a single spec- imen collected on Mindanao Island in 1906. A second example, also from Mindanao, was ob- tained in 1923 (Fig. 1). Musser (1982) described C. rabori from one specimen collected on Leyte Island in 1964 (Fig. 1). This is an old adult male that is considerably larger and somewhat paler than the Mindanao specimens, both of which are younger. Musser and Heaney (1992) suggested that the morphological differences between these island samples might reflect age variation, and they questioned the distinctiveness of C. rabori. Our recent field surveys on Mindanao and Ca- miguin islands (Fig. 1 ) yielded seven specimens of Crunomys with external, cranial, and dental characteristics that agree with Musser's (1982) emended diagnosis of C. melanius. This series in- cludes individuals of both sexes and various ages that span the gap in size and proportions seen be- tween the earlier specimens from Mindanao and the one from Leyte (Tables 1, 2). They also dis- play minor variation in color and texture of pel- age. Two adults from Mindanao are dark brown above and grayish brown on sides and below and have harsh pelage with spiny dorsal awns. Four specimens from Camiguin are slightly darker overall with faint red or yellow tones; one adult has spiny dorsal awns, whereas a juvenile and two young adults have pelage that is stiff but slightly softer. Age appears to account for most of the variation in size and pelage characteristics in the total sample. Accordingly, we identify all of these specimens as C. melanius. and consider C rabori to be a synonym. Crunomys melanius has been collected in for- ested habitats from near sea level to 1550 m ele- HELDIANA: ZOOLOGY (o H K- s- ^3 CO aa X cfl asrt z2 ^2 aa - g:^ has -* r^. -T -t I/-. I/", I/". n 1^ sC ^C >c <". -^ i/~, 00 o) c-, n 00 "^^ S c U ':::; ■* ri >/", vC ^ O n ^C ^ O \C ^ :> •* — -^ ri — ,^ ^_ 00 ri ^ •-r CD r^. w oi ri r^ r^ -r ri ■^ C I/-, -Tf I^ ^ Tj- Tf ^ — >/". ri -'^ Tt ri <^l ^ « t^ n c , ^ ^ ri ri Ol >^_ c X I I X li X ^^ X X X X: r3 -3 z z z z i) z s z z z :^ S S S S £ S >. S 5 S S s ^ - — X < u. H- r3 ^ ^ ^ < < < r= S U J ? c c 5 Ov ^ ^ — X 5: ■ — S z "^ 2 S -c X X X 2 ^ X -S 5 RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS vation. Two specimens from Mt. Katanglad. Min- danao, were trapped near holes on the ground in primary montane forest where some moss cover was present; the species appeared to be uncom- mon (Heaney et al., 1997). Five specimens from Camiguin were taken at elevations between 900 and 1275 m. in secondary lowland rainforest and in lightly disturbed and primary montane rainfor- est; the species apparently was at low densities at all sites, and it was trapped only beneath rotten logs and wood tangles in areas with few dead leaves and little moss (Heaney & Tabaranza, 1997). During our survey of the Mt. Katanglad Range, we obtained another specimen of Crunomys that differs from previously known members of the genus. This represents a new species that we name and describe as follows: Crunomys suncoides, new species (Figs. 2, 4-9) HoLOTYPE — Adult male, fmnh 147942; collect- ed 10 April 1993 (original number 5330 of L. R. Heaney); initially fixed in formalin, now pre- served in ethyl alcohol with the skull removed and cleaned. The stomach and both femora have been removed; otherwise the specimen is in ex- cellent condition. It is deposited at fmnh but will be transferred to pnm. Typh Locality — Mt. Katanglad Range. 18.5 km S, 4 km E Camp Phillips, Bukidnon Province, Mindanao Island, Philippines, 2250 m elevation, 8°9'30"N, 124°5rE (Fig. 1). DiSTRiBiTioN — Known only from the type lo- cality in the Mt. Katanglad Range, but may occur elsewhere in high-elevation forest on the island of Mindanao. Referred Specimens — None. The holotype is the only known example. Measurements — Table 1 . Etymology — The specific name suncoides re- fers to the striking superficial resemblance in body form to the common house shrew, Suncus tmihmis. We suggest the common name ''Katang- lad shrew-mouse." Diagnosis — A species of Crunomys grouped with other members of the genus and distin- guished from Archboldomys by the following characters: (1) patterned pelage coloration, darkest mid-dorsally, paler on sides, and palest ventrally; (2) ventral maxillary roots of the zy- gomatic plates not overlapping the first molar; (3) absence of stapedial foramina and arteries, and a derived pattern of cephalic arterial circulation; (4) absence of squamoso-mastoid vacuities; (5) upper and lower third molars that are much smaller in comparison to the other molars. It is distinguished from other species of Crunomys and also from Archboldomys by the following combination of traits: (1) general orange brown pelage: (2) large front feet with long, stout claws; (3) sharply bi- colored tail nearly equal in length to the combined head and body length; (4) narrow skull with a relatively long and narrow rostrum; (5) thin, elon- gate mandibles; (6) small molars, both absolutely and relative to the size of the skull and mandibles; (7) absence of cusp t9 from first upper molar; (8) presence of cusp t3 on second upper molar. Description and Comparisons — Crunomys suncoides is a small murine rodent (weight 37 g), with a narrow head, elongate snout, large feet with strong toes and claws, and a tail that is nearly as long as the combined length of head and body (Fig. 2). In most dimensions the new species is larger than C fallax but smaller than other mem- bers of the genus (Table 1), and there are sub- stantial proportional differences in external, cra- nial, and dental measurements (Table 2; Figs. 3, 4). The new species has pelage that is dense and relatively short (Table 1), and soft as in C. cele- bensis rather than spiny or harsh as in C fallax and C. melanius. Most hairs in the overfur are tricolored, uniformly pale gray for % of the length from the base, followed by a narrow black band and an orange-brown tip. Ventral hairs are shorter and bicolored (gray with orange-brown tips). The general pelage color is rich orange-brown, and it is patterned much as in other Crunomys. Color mid-dorsally, on top of the head and on the rump, is dark brown with slight orange tint, grad- ing to a paler shade on the sides. Dorsal and lat- eral surfaces of the muzzle are blackish brown. Upperparts are slightly grizzled from a general scattering of uniformly pale gray hairs. Under- parts are paler, but there is no sharp lateral delin- eation. The chest and upper belly are bright or- ange-brown, with more extensive gray on the throat and lower belly. The urogenital region is sparsely covered with short gray hairs, and the base of the tail behind the anus is blackish brown. The snout is elongate, with a flexible cartilag- inous tip 4 mm long. The rhinarium and lips are unpigmented. Each of the very small eyes (di- ameter ca. 2 mm) is surrounded by a narrow (ca. 1 mm) ring that lacks pigment or hair Facial vi- FIELDIANA: ZOOLOGY Fig. 2. Adult male Crunomys suncnides (FMNH 147942, holotypc) brissae are blackish gray and relatively short, the mystacials reaching no further than the ears. The pinnae are small, nearly naked, and nearly unpig- mented. On the external surface of the pinna, there are only a few fine hairs near the base, with both density and diameter of hairs increasing slightly toward the margin. The internal surface is similar, but with even fewer, shorter, and finer hairs. Dorsal surfaces of the front and hind feet are unpigmented. sparsely covered with short sil- ver hairs and with a scattering of slightly longer black hairs over the metapodials. The palmar sur- face is naked and unpigmented. The plantar sur- face is naked, with mottled pale gray pigmenta- tion on the metapodials and unpigmented heel and digits. In contrast to the other species of Crunomys and Archboldomys, the tail of C. suncoides is nearly as long as the head and body combined rather than substantially shorter (Table 2). The tail is sharply bicolored, as is the case with C. fallax, but unlike the other species. The dorsal surface and sides are uniformly dark grayish brown, and the undersurface is unpigmented. Scales are mod- erately small (20 rows per cm), and each is as- sociated with three short (<1 mm), stiff hairs. Hairs on the dorsal surface are dark gray, whereas those on the underside are silver. Compared to other Crunomys, the front feet are relatively large and have strong digits. There is a thick nail on the pollex, and the other digits have pale claws that are long, stout, and only slightly recurved. The palmar surface has five pads: three small interdigitals, a small medial metacarpal, and a large lateral metacarpal. The hind feet and digits are elongate and bear stout claws. The six plantar pads include four small interdigitals, a tiny medial metatarsal (hypothenar). and a larger lateral meta- tarsal (thenar); all are very small compared to the total plantar surface area. The narrow, elongate head of Crunomys sun- coides is reflected in the cranial structure. Viewed from above (Fig. 5), the skull is nearly triangular in outline. Compared to the other Crunomys, the rostrum is relatively long, narrow, and smoothly tapered (Table 2). The nasal bones are slender and have strongly sloping sides, giving the rostrum a tubular appearance. The frontal sinuses are inflat- ed, and the interorbital region is relatively broad. The dorsolateral margins of the interorbital and RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS -.20 -.15 -.10 .05 0 .05 .10 C. melanius C. suncoides LHB LT LHF LE GLS ZB IB BBC* HBC LR BR BZP LD PL PPL* LIP LPB PBM1 LM1-3 LM HM Lm1-3 Fig. 3. Ratio diagram comparing log-transformed measurements of Cnmomys suncoides to those of adult C melanius (mean ± 2 standard cn-ors [SE]). Asterisks denote measurements that differ significantly (P < ().()5; Student's ^tests). postorbital regions and the braincase are entirely smooth, with no traces of supraorbital or temporal ridges. In comparison to the other species, zygo- matic breadth and braincase breadth are modest relative to the overall length of the skull (Table 2; Figs. 3, 4). The zygomatic arches are thin and delicate, and are strongly backswept from their anterior roots. Zygomatic breadth exceeds brain- case breadth only slightly. The braincase is nar- row and rounded. The interparietal is relatively short (front to back) and narrow. The occiput is inflated posteriorly, projecting substantially be- yond the occipital condyles. Viewed laterally (Fig. 5), the dorsal profile of the skull of C. suncoides describes a nearly straight slope from the middle of the brainca.se to the nasal tips. The braincase is relatively flat dor- sally, but it is inflated posteriorly to a degree not seen in other Crunomys. The tips of the nasal bones are straight and project slightly beyond the premaxillaries. Both the nasals and premaxillaries project beyond the anterior face of the incisors, forming a tubular nasal opening. The opening to the nasolacrimal canal at the base of the rostrum is conspicuous and directed dorsally, and the ca- nal itself is moderately expanded. The relatively narrow zygomatic plate has a slightly concave an- terior margin, and the posterior margin is even with the anterior edge of the first molar. In con- trast to the other species of Crunomys, the zygo- matic plate slants backward as in Archboldomys luzonensis. There are features of the orbital region of C. suncoides that are distinctive. The orbit is con- stricted laterally by the slight outward bow of the zygomatic arch and medially by the extreme in- flation of the frontal, maxillary, and palatine bones. In contrast to the other species of Cruno- mys and Archboldomys, the sphenopalatine fora- men is nearly hidden at the anterior end of a deep, narrow groove formed by the near contact of the inflated orbital process of the palatine and the maxillary bone immediately above the molars. The position of the dorsal palatine foramen (which is coalesced with the sphenopalatine fo- ramen in the other species) is obscured within this groove. There is a structural difference between the left and right alisphenoid regions in the holotype. On the left side there is an alisphenoid strut forming the lateral wall of the alisphenoid canal and sep- arating the foramen ovale accessorius from the coalesced masticatory and buccinator foramina. This same arrangement is characteristic of Arch- boldomys luzonensis. The right side lacks an ali- sphenoid strut and displays the general morphol- ogy seen in all other species of Crunomys (Mus- ser, 1982, p. 35. fig. 23). The squamosal, bullar, and mastoid regions of C. suncoides are similar to those of other mem- bers of the genus (Fig. 6A; Musser. 1982, p. 37, fig. 24). The bulla is broadly separated from the squamosal and much of the alisphenoid by the contiguous postglenoid vacuity and postalar fis- sure. The surface of the mastoid is slightly inflat- ed and without fenestration. Along the dorsal mar- gin there is a small mastoid foramen situated in the occipital suture. Along the anterior margin, the suture with the squamosal is entire and without the vacuity seen in Archboldomys. A squamoso- 10 FIELDIANA: ZOOLOGY Fig. 4. Ventral views of the palatal region of A, Cnmomys smwoides (fmnh 147942. holotypc) and B, Cnmomys melaniiis (fMNH 147105). mastoid foramen cannot be located within the su- ture. On the ventral aspect of the skull (Figs. 4A, 5) there is a small interpremaxillary foramen situated between the incisor alveoli. Each premaxilla has a prominent pit just posterior to the incisor. As in other species of Crunomys, the incisive foramina are narrow and short relative to the length of the diastema (Table 2). Lateral to the incisive foram- ina, the maxillae are fully ossified. The surface of the bony palate is slightly pitted, with prominent palatine grooves extending from the incisive fo- ramina to the posterior border of the palatal bridge. The posterior palatine foramina are large, RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 11 cr» Fig. 5. Dorsal, ventral, and lateral views of the cranium, and lateral view of the left mandible of Crunomys suncoides (FMNH 147942, holotype). Measurements are in Table 1. but in ventral view they are partly hidden within the palatine grooves. They are located just ante- rior to the suture between the maxillary and pal- atine bones at a level opposite the posterior por- tion of the first molar. A pair of smaller foramina are located near the posterior border of the palate. The mesopterygoid fossa is narrow relative to the posterior breadth of the palate, and the sides and top are nearly complete, with sphenopalatine va- cuities that are small in comparison to those of C. melanius or A. luzonensis. As in other Crunomys, the surface of the pter- ygoid fossa is entire (Figs. 4, 7A), without the large sphenopterygoid vacuity seen in A. luzonen- sis (Musser, 1982, p. 44, fig. 30). On the posterior portion of the pterygoid plate, a short, diagonal 12 FIELDIANA: ZOOLOGY ■ / ■— smv ■ ^^^^^^^^^^ \ \ ma 4 ^^^^^H ^ '^' 4 ^ 'v^^^^^H [bL .,,,._..._... .v_ V . • ■; . - . : r"- ab W IJ^^H Fig. 6. Lateral views of squamosal, bullar. and mastoid regions o\' A, CninoDnw suncoide.s (fmnh 147942, holo- type) and B, Archbuldomys musseri (fmnh 147176. holotype). Anterior is to the right. Abbreviations: ab. auditory bulla; al, alisphenoid; ma, mastoid; maf, mastoid fenestra; paf-t, postalar fissure covered by thin tissue; pgv, post- glenoid vacuity; pgv-t, postglenoid vacuity covered by thin tissue; sq. squamosal; smv. squamoso-mastoid vacuity. groove between the transverse canal and the pos- terior opening of the alisphenoid canal marks the path of a secondary branch of the internal carotid artery. This arrangement, presumed to be derived (Musser & Heaney. 1992), is seen in other Crii- nomys, but not in Archboldomys (Musser. 1982. pp. 44, 45, figs. 30. 31). As in Cnmomys melan- ius, this arterial pattern is also reflected on the medial surface of each auditory bulla, where there is no trace of a stapedial foramen or artery (Mus- ser, 1982, pp. 40, 41, figs. 27, 28). In comparison to other species of Cnmomys and Archboldomys, the mandibles of C. suncoides are exceptionally slender (Fig. 5; Tables 1. 2). The coronoid process is small in relation to the overall size of the mandible. The condyloid and angular processes are long and thin, resulting in a deeply concave posterior border. The labial surface of the mandible is relatively smooth. The bony ridge along the ventrolateral margin is less prominent than in C. melanius, extending from a point even with the middle of the first molar to the base of RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 13 Fig. 7. Ventral views of pterygoid region of A, Criinomys suncoides (fmnh 147942, holotype) and B, Archhol- domys musseri (fmnh 147176, holotype). Anterior is to the top. Abbreviations: ab, auditory bulla: al. alisphenoid: iag, groove for infraorbital branch of stapedial artery; icg, groove for secondary branch of internal carotid artery; ptf, pterygoid fossa; .sq, .squamosal. the angular process. The base of the incisor cap- sule forms only a slight bulge below the coronoid. The shape and position of the mental and man- dibular foramina are similar to those of the other species. The enamel of both the upper and lower inci- sors is pale yellow. The upper incisors emerge at right angles to the rostrum and are slender, with a depth only slightly greater than the width. The delicate and elongate lower incisors describe a relatively shallow arc, and their anterior surfaces are rounded, causing the tips to wear to a sharp point. In contrast, C. melanius has upper incisors that are more than twice as deep as they are wide and strong lower incisors that curve more sharply, have flattened anterior surfaces, and have broader, chisel-shaped tips. The holotype of C. suncoides has molars that are extremely worn (Fig. 8A,C). The overall shape of the teeth and what remains of the cusp patterns resemble those of other Cm- mmiys (Musser, 1982, pp. 13, 25, figs. 7, 15), al- though there are some distinctive features. In con- trast to other Cninomys. the posterolabial cusp (t9) appears to be lost from the first upper molar. As in C. fallax, but in contrast to the other species of Cninomys and Archboldomys, a small antero- labial cusp (t3) is present on the second upper molar. Finally, the molars of C. suncoides are sub- stantially smaller than those of all other Cninomys and Archboldomys. both absolutely and relative to the length of the palate and mandible (Figs. 4, 12; Tables 1,2). Although the holotype of C. suncoides was caught dead in a snap trap, it was very fresh when recovered, and it provided basic data on chro- mosomes. The standard karyotype (Fig. 9A) con- sists of 1 8 pairs of small- to large-sized chromo- somes, all of which appear to be telocentric (2N = 36; fundamental number [FN] = 36). The sex chromosomes cannot be differentiated from the autosomes. No other species of Cninomys has been karyotyped to date. Archboldomys luzonen- 14 FIELDIANA: ZOOLOGY Fig. 8. Occlusal views of left molar toothrows of Crunomys suncoides (fmnh 147942. holotype: A, maxillary; C, mandibular), and Archholdomys musseri (fmxh 147176. holotype: B, maxillary: D, mandibular). Measurements are in Table 1. In C suncoides. note the absence of cusp t9 from the first upper molar and presence of cusp t3 on the second upper molar. In A. musseri. note the presence of cusps t3 and t9 on the first upper molar. sis has a diploid number of 26. a fundamental number of 43. and a distinctive sex chromosome system (Fig. 9B; Rickart & Musser. 1993. p. 8. fig. 5). These two karyotypes are quite different, although both have relatively low fundamental numbers near 40. Ecology — The holotype of Crunomys suncoi- des was taken in primary forest at an elevation 2250 m in the Mt. Katanglad Range. The type locality is located on a steep, north-south-oriented ridge on the northern flank of the range, with veg- etation transitional between upper montane and lower mossy forest. Dominant trees include sev- eral species of gymnosperms and laurels. Forest canopy is 7-10 m high and broken by many tree falls. Breast-height trunk diameters of canopy trees are 8-30 cm. Emergent trees are 12-15 m high on the main ridge and 14-18 m on hillsides, with breast-height diameters of 40-100 cm. Epi- phytes including moss, lichen, ferns, and orchids are common. Understory plants include saplings. Rhododendron, and other shrubs, ferns, and sedges. Substrate consists of rocky, volcanic soil covered with deep humus (10-50 cm) and thick surface leaf litter The holotype was trapped near a small hole at the bottom of a small, steep gully on the west side of the main ridge just below the ridge crest. Other murids trapped at the type lo- cality included Apomys hylocetes. Apomys insig- nis. Batomxs salonnmseni. Limnomys sibuanus, Tarsomys opoensis. and an undescribed species of Limnomys. The gymnure Podogymnura truei and the tree shrew Urogale evereti also were present. The shrew Crocidura becitus was trapped at ad- jacent lower and higher elevation sites, but it was not taken at the type locality. Bats recorded at the type locality included Alionycteris paucidentata, Haplonycteris fischeri. Macroglossus minimus, Rhinolophus inops. and Pipistrellus javanicus. Long, slender hind feet with small plantar pads and a tail that is somewhat shorter than the com- bined head and body lengths indicate that Cru- RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 15 A }| II U II M II II a II H H •■ »* OA •• •• •• •• 10 |ini B C( II II n » CI II I llMNii MN<4^. huiui.y|X\ ^N - St\\ «uul H, , I >> .Son v'l>h>i\\oM>mov ol' {\ \Mm"t>v kMm\« X ^ (Wi/r'A ttwtlo .V<. I'N - ||>ryc CIttWS. i\ u.iu>'\\ h>-.ul. iiin st>n»i t»>vsoiu>l hi»l>u As IN (ho crtso with oUum innwhns ol ihr _v.*vm\uv. (ho s|Vv'tos |Mvh>(\|v was V apuu\\l luul .»IIv-iiu>om (Ctt. 15(H) h^ u\ .» sn.ip II. ip h.iiliil w ilh i h\ »• i;iul\ \voin\ Iho snuill shM\u»vh was ompu anvl ihoiv is iu> inh>uuain>n vm\ \hvM I ho spovios M\a\ loovl on soh huihovl iuvvmU'ImjUcs a.s docs .An/t/s >/»/<•»«>> /MjoMfmjv iKivkaii 01 rtl. |OUh The hv>lvM\po is m old mluU ntulc thai <(p|>c(uvd (o be in blx^cdi)\^ vvMuliUou v\hoi\ oapiuivvl itinw. voi\»l«>l losios. tho Iai)i0\l inoasunnw! IJ v S \\\\\\\ An >n U\o oaso wiih oihoi iruthmiw, (" vm*i k'ihiiUy {s vhtt\ouU lo oapuiir. (ho su\)ilc uuUvulual \V«>i ohlttiUlHl rtlWv UUMV \\\i\\\ ^^.IHH) Mrtp-nijihis M Iho »\|V looahlN U was u\>» ivooulovl ai Kw\o» ol o\alivM\s vMi Nil Kaianvjlavl viospuo i\\v>to than 4,>im uap \\\^\\\\ Ivlwoou 1 HH) aiul l*MH) u\. hvwv o\c». Us ivUliNC. t\ mW*miMA. was lakon at l^M) ^«5t) lu. vuu Urtppu\)4 olTvMls A\ hijihct olo\aliot\s vvc»v hu\Uo\l ['^' uap nijjhiN at ,M *«v ju. 4rx^ ai XH» u\. ami MO al ;StH) uO IhC SU\);K' hioh k-1k\;UI.M> 1\'>,>I,I 1,>I l'l!«»i«WM\\ \iinii>iili\ IS III '.h.iip toiili.isl lo ihi' known ok" v.iiKMi.il ihsliihudons ol iis i onj^'oncrs, l';icvali»)n ol (III- typo looahly oxooiuls ilu- known nppci ol ovtilion oxiionios lor Iho olhoi spi-ou's ol Cnino ni\:\ h\ sovoral luiiuiiod inolois ( iiinnniw sun ti'iiltw liki'lv on ins in hijjh olovation lorost hah II. ii iluoiii-lixiii lilt- Ml KalanghKl Range, and it. Ol a lUMi u-laliM'. iii.iN he piosrni in aroasolhii'li land loirsi i-lsi'whoii- on Miiiilanao Ilu- oiiinroiuo tiiiv\ in Iho ^h KalaHjiLul Kan,^'.l• u-llools a palloin sv-rn ttiuong olhcr nuniil gciui i liom ihis urion Iho known looalilios \\n Cniniunw sunii'ithw ami (' mrltinius aio soparalod In 700 in olo\ali»»n, Iho two .species nuiy havo nonovoi lapping oloxaimnal langcs, as is the ca.se wiih r,irstntiy.\ tilimttiiis «nd Tttmmiys oiun'nxis In » oniiasl. ,'\/>«»/»\.v in- st\tni\ ami ,\/to;M\'.v hyhuiifs ha\o partially ovci'- lapping ranges on Ml Kaianghul. as ilo I ininiwtys \ihii>inu.\ and an niulosonhovl spooios ol I intn<>iii\s (Mvissei .'s llranr\. I'J'>.\ Kukarl .V; Hoaney. un publ iiata) \,,Utu>hlomvs Mii.s,scr. l*»s: Typh Sphcihs— v4*"t7«/>«>/cA)»MV.v luztmtnsis Mus set (I oh:, p. .^0) PiViiNost.s A v.i'iuis ol siu.ill. U'liosdi.il mil iiiu- iihIiuIs ih.il IS m>mv,V. bill vlisiingiiisliid In ilu- lolKiwinv. oharaotofs: (\) long. si\li lui wiihoui spun Ol haish awns: (2) \>\i'i;ill li.iik iiupaiioinod pol.igo. ^ ^^ \oniial iua\ illaiN uH'i ol tho .-\gv>ma(io plalo partly v>\oilap ptng liisi vippii mol.ii. (4) oephalio aiteiial cii'- oiilattvMt in\ol\ing a pion\inoi\t stapedial aHeiy: ^^^ pifsenoe v>l an onlargovi svjvianuvso-inastoid \a- oiiiin; ^^) slettdoj manihhlo wiih elongate oow- nv>ul |>uvess; ("*^ niol.ns wiih l.iigo. ov>nioal ovisps; (S) tippi'i .Hui K>Wk-i ihiut mol.iis laiv'.oi lol.ilivo U> ei\titv looihiow ro\ii\i v\p nisiKim no\ As pivsonih un vloisiv>v>vl. (ho gonns An hl>i^lJow\\ is ovM\Hnovl lo the IMtdippino island »>l I u.-v>n and inohulos iwv^ s|>cvics. Istu ovi shrc>> -mouse RtMXRKS— The gonns \nhht>hiim\s. with the t\|v sjHX'ics .A /M*«»nf«M,v. was dcscnlvd by Mns SOI vl*^^^.'^ tu>n\ a single s|vouuon ooUootovl v>n Ml. IsiUvg in s,MnhoasUMn I u:v>n Snbsovjviont snr lo Mlii .DIANA; ZCKM ^H;^ Fui. 10. Acluli male An lihoUlomy.s inusseri (IMNH I4717(\ holoiypc). Scale bar = 5 cm. vcys oj Ml. Isarog have yielded 13 additional ex- amples of A. luzonensis ihal are consistent with Musser's original diagnosis. The species is known only Irom upper montane and mossy forest habi- tats above 1.3(M) m elevation on Mt. Isarog. As is the case with Cninoniys, A. luzonensis is difficult to capture: in one survey, only eight individuals were taken during 4,900 trap-nights (Rickart et al., 1991). Most of these were not attracted to bails but were caught because they ran across the treadles of snap traps positioned on the ground either in runways or directly in front of burrow openings. Stomach contents indicate a diet of in- vertebrates (adult and larval insects, terrestrial crustaceans, and earthworms). The species is probably strictly diurnal: most individuals were known to have been capiurcii during daylight hours (Rickart et al., 1991). Musser (1982) hypothesized that /\ luzonensis or a close relative might occur in ihc high moun- tains of northern Luzon. This disinbuiional pat- tern is seen among other endemic murid genera represented in the high-elevation fauna of Mt. Is- arog (Musser & l-reeman, 1981; Musser, 1982; Rickart & Heaiiey, 1991). Musser was correct. In 1992 a shrew-mouse was discovered in the north- ern Sierra Madre range of northeastern Luzon The external and cranial features of this animal distinguish it as a .second species of AnhholJo- niYS that we name aiul describe below, Archholdomys musseri, new species (Figs. 6-10, 12, 13) Hoi.oTYPK — Adult male, hmnh 147176; collect- ed 15 May 1992 (original number 2092 of D. S. Balete); initially lixed in formalin, now preserved in ethyl alcohol with the skull remo\ed and cleaned. The specimen is in excellent condition. Currently it is deposited at imnh but will be trans- lened to pnm. Tvi'i-. Locality — Mi. C'eiaceo. Siena Madre Range, Callao Municipality. Cagayan Province. Luzon Island, Philippines. 1650 m elevation. I7°42'N, I22''02'E (Fig. I). DisiKiiuiioN — Known only from the type lo- cality but may be more widely distributed in the mountains of northern Luzon. Ri.ii.KKii) Si'i.c iMi.N — One. from the same lo- cality as the holotype. deposited at pnm. Mi.ASt KhMi:Nis — Table I . KiNVioKHiY — Named in honor of (Juy G. Mus- ser. in recognitit>n of his many outstanding con- lributit)ns as the leading authority on St)utheasi Asian murid rodents. We suggest the common name "Sierra Madre shrew-mouse." in recogni- tion of the newly declared Northern Siena Madre Wilderness Park, the largest park in the Philip- pines. DiAdNosis — A species ol Archholdomys that is distinguished from all members of the genus Cru- RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 17 nomyy and grouped with A. luzonensis by the fol- lowing combination of characters: (1) overall dark, unpatterncd pelage; (2) ventral maxillary roots of the zygomatic plates partly overlapping the first upper molar; (3) well-developed stapedial foramina and arteries, and retention of a primitive pattern of cephalic arterial circulation; (4) prom- inent squamoso-mastoid vacuities; (5) upper and lower third molars that are larger relative to the other molars, h is distinguished from A. luzonen- sis by: (1) smaller size; (2) longer tail; (3) nar- rower skull with a relatively shorter, narrower ros- trum; (4) nasal bones with straight as opposed to upturned tips; (5) shorter incisive foramina; (6) absence of large sphenopterygoid vacuities; (7) relatively small postglenoid vacuities; (8) promi- nent mastoid fenestrae; (9) molars that are much smaller, both absolutely and proportionately; (10) presence of labial cusps t3 and t9 on the first up- per molars. Description and Comparisons — Archboldomys musseri is a small murid with a stocky body, small fore- and hind feet, and a tail that is slightly short- er than the combined length of head and body (Fig. 10). Its overall form is similar to that of A. luzonensis, but it is smaller (Table 1), and there are many proportional differences in external, cra- nial, and dental measurements (Table 2; Figs. 11, 12). The new species has fur that is soft and long, as does A. luzonensis, but the mid-dorsal fur of A. musseri is somewhat shorter (Table 1 ). Dorsal hairs are tricolored; they are uniformly medium gray for about % of the length from the base, fol- lowed by a black band with a reddish brown tip. Ventral hairs are shorter and have paler tips. Coloration is very similar to A. luzonensis. The upperparts are uniformly dark reddish brown without the darker patterning on the head, legs, mid-dorsum, and rump characteristic of Cruno- mys. There is no sharp color delineation between the dorsum and venter, but the underparts are pal- er, with a yellowish gray cast. The lips have pale gray pigmentation, and the rhinarium is darker gray. The eyelids are edged in black and sur- rounded by a narrow (<1 mm) pale gray ring. Mystacial vibrissae are blackish gray and mod- erately long, extending beyond the ears. The small, round ears are uniformly dark gray with a sparse covering of dark hairs. Dorsal surfaces of the feet are uniformly pigmented (fore feet brownish gray, hind feet brownish black) and sparsely covered with short, dark hairs. Both the palmar and plantar surfaces are naked and pig- .20 -.15 .10 -.05 .05 .10 A. luzonensis Lm1-3** Fig. 1 1 . Ratio diagram comparing log-lransformcd measurements of Arxhholdomys musseri to those of adult A. luzonensis (mean ± 2 SE). Asterisks denote measurements that differ significantly (* P < 0.05. ** f < 0.01; Student's Mcsts). mented dark brownish gray except for the pads, which are paler. The tail is shorter than the combined head and body length, but it is both relatively and abso- lutely longer than in A. luzonensis and is more finely scaled (Tables 1, 2; Fig. 11). The tail is uniformly blackish gray, without a bicolored pat- tern. There are three blackish hairs associated with each scale. The front feet are relatively small, with slender digits. The hind feet and digits are long and nar- row, but they are substantially smaller than in A. luzonensis (Table 1 ; Fig. 1 1 ). The pollex bears a nail, and all other digits have long, narrow claws that are nearly white in color. There are five pads on the palmar surface: three small interdigitals, a 18 FIELDIANA: ZOOLOGY Fig. 12. Ventral views of the palatal region of A, Archboldumys imissen (imnh 147176. holotypc) and B, Arch- holdomxs htzonensis (FMNH 147173). small medial metacaq?al, and a larger lateral meta- carpal. The plantar surface bears four interdigitals, a medial metatarsal, and a lateral metatarsal, all of which are relatively small. The cranium of Archboldomys miisseri is sim- ilar in general moiphology to that of A. luzonen- sis, although it is substantially smaller in most di- mensions (Table 1 ). Viewed dorsally (Fig. 13), the overall shape of the skull is elongate and narrow. Compared to A. luzonensis, the rostrum is short and narrow, and the nasals are elongate relative to the length of the skull (Fig. 1 1; Table 2). The interorbital region is relatively broad, and the sur- face of the postorbital area and the braincase are RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 19 Fig. 13. Dorsal, ventral, and lateral views of the cranium, and lateral view of the right mandible of Arcliholdomys musseri (fmnh 147176, holotype). Mea.surements are in Table 1. smooth and without ridges. Zygomatic breadth is modest relative to the length of the skull and the width of the braincase (Tables 1, 2), and the zy- gomatic arches are slender and delicate. The brainca.se is rectangular, as in A. luzonensis. but more elongate. In side view (Fig. 13), the dorsal profile of the skull is nearly straight from the top of the brain- case to the tips of the nasal bones. These are slightly damaged in the holotype, but they are clearly straight, rather than upturned, as in A. lu- zonensis (Musser, 1982, p. 21, fig. 13). The brain- case is domed but not as inflated as in A. luzo- nensis. The nasal and premaxillary bones project only slightly beyond the anterior face of the in- cisors. The nasolacrimal canal slightly inflates the base of the rostrum. The opening of this canal is narrow and elongate, and it is directed slightly caudad. The zygomatic plate is narrower than in A. luzonensis. and the slightly concave anterior 20 FIELDIANA: ZOOLOGY edge is oriented vertically rather than slanting backward. However, in both species the posterior margin of the plate extends slightly behind the anterior margin of the first molar. The squamosal root of the zygomatic arch is positioned higher on the braincase than in A. luzonensis, substantially above the level of the postglenoid vacuity. The sizes and positions of the orbital foramina in the new species are similar to those seen in A. luzonensis. The sphenopalatine foramen is closely associated with the dorsal palatine foramen, and together they form a long narrow opening in the ventral medial wall of the orbit. On each side of the braincase there is a well- developed alisphenoid strut that forms the lateral wall of the alisphenoid canal and separates the foramen ovale accessorius from the coalesced masticatory and buccinator foramina. This is sim- ilar to the arrangement in A. luzonensis (Musser, 1982, p. 35, fig. 23). although the strut is consid- erably broader and more robust in the new spe- cies. The presence of an alisphenoid strut distin- guishes the genus Archboldomys from all Cru- nomys with the exception of C. suncoides (see above). The new species of Archboldomys exhibits a unique combination of features in the squamosal, bullar, and mastoid regions (Fig. 6B). The audi- tory bullae are similar in general structure to those of A. luzonensis, although they are less inflated. In clear contrast to A. luzonensis and all species of Crunomys, the postglenoid vacuity is relatively small and the postalar fissure not broadly open. As a result, the anterior margin of each bulla is in contact with the squamosal as well as the ali- sphenoid. As is the case with A. luzonensis (but unlike Crunomys), the squamoso-mastoid fora- men is enlarged, forming a prominent vacuity along the posterior edge of the squamosal above each bulla. However, compared to A. luzonensis (Musser, 1982. p. 24. fig. 24), the vacuity is small, and that portion of the squamosal ventral to it is much broader As in A. luzonensis, the occipital suture along the dorsal margin of each mastoid contains a small mastoid foramen. There also is a prominent mastoid fenestra near the dorsal margin of each mastoid. A comparable fenestra is seen in Crunomys celebensis (Musser, 1982, p. 38, fig. 25) but not in any of the other taxa. In ventral view (Figs. 12A, 13), there are sev- eral distinctive cranial features. The prominent in- terpremaxillary foramen seen in A. luzonensis is absent, although there are several tiny paired fo- ramina posterior to the incisors. The incisive fo- ramina are short, both absolutely and relative to the length of the diastema, rather than long as in A. luzonensis (Tables 1, 2; Fig. 12). The maxillae lateral to the incisive foramina are fully ossified, and the surface of the bony palate is smooth. Shal- low palatine grooves extend from the incisive fo- ramina to the posterior palatine foramina. The mesopterygoid and pterygoid regions of A. musseri include some distinctive features. The mesopterygoid fossa is narrow relative to the pal- ate. Aside from a small, membrane-covered sphenopalatine vacuity on the right wall, the dor- sal and lateral surfaces are entirely ossified. The surface of each pterygoid fossa is entire (Figs. 7B. 12A), without the sphenopterygoid vacuities seen in A. luzonensis (Fig. 12B; Musser, 1982. p. 44, fig. 30). The posterior portion of the pterygoid plate contains a groove for the interorbital branch of the stapedial artery (Fig. 73). This constitutes the primitive arterial pattern seen also in A. lu- zonensis, and it is contrasted with the presumed derived pattern seen in Crunomys (Fig 7A; Mus- ser. 1982, pp. 44, 45, figs. 30, 31). The pattern also is reflected in the large stapedial foramen and arterial channel on the medial surface of each au- ditory bulla; the same structures are present in A. luzonensis but are absent or very much reduced in Crunomys (Musser, 1982. pp. 40, 41, figs. 27, 28). The mandibles of A. musseri (Fig. 13) are sim- ilar to those of A. luzonensis in general form and in the positioning of mental and mandibular fo- ramina, but they are smaller and more slender (Ta- bles 1, 2). The labial surface of the mandible is smooth, and there is no swelling at the end of the incisor capsule at the base of the coronoid pro- cess. A short ridge on the ventrolateral surface extends from the level of the second molar to the base of the angular process. The condyloid pro- cess is elongate and slender, and the condyle is relatively small. The angular process also is slen- der, so that the posterior margin of the mandible is deeply concave. Relative to the overall size of the mandible, the coronoid process is extremely long, thin, and backswept, extending back to a point even with the anterior edge of the condyle. To a lesser extent, A. luzonensis shares this trait, whereas all Crunomys have relatively short cor- onoid processes (Fig. 5; Musser, 1982, pp. 21,91, figs. 13, 59; Musser & Heaney, 1992, p. 72, fig. 40). The incisors of the new species are similar in general form to those of A. luzonensis, but they are more delicate. The slender upper incisors RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 21 emerge at right angles from the rostrum, and they have relatively flat anterior faces and straight- edged tips. The lower incisors are slender, with slightly flattened anterior surfaces and narrow, chisel-shaped tips. The enamel on the upper in- cisors is orange, and that on the lower incisors is a paler yellowish orange. Although the holotype of i4. musseri has very worn molars (Fig. 8B,D). some important differences are evident in com- parison tOi4. luzonensis (Musser & Heaney, 1992. pp. 70, 71, figs. 38. 39). The molars of the new species are much smaller, both absolutely and rel- ative to palate and mandible lengths (Figs. 11. 12; Tables 1. 2). Small labial cusps t3 and t9 are pres- ent on the first upper molar of A. musseri, whereas these cusps are absent in A. luzonensis. In other respects, cusp patterns of the two species appear to be similar. In both species (but particularly A. musseri). the size of the upper and lower third molars relative to the other molars is much greater than in any Crunomys. Ecology — Vegetation at the type locality was described by Danielsen et al. (1994) as "mossy forest . . . characterized by a low, dense and en- tangled forest with a canopy height decreasing with elevation from 10 to 3-4 m on the highest and more exposed parts. The canopy cover was 70-90 percent. The trees were densely covered by mosses and contained an abundance of epiphytes such as orchids, pitcher-plants (Nepenthes) and ferns." The specimens were initially misidentified as Crunomys falla.x, and were reported as such by Danielsen et al. (1994). Other small mammals trapped in the area were Apomys dame and Rattus everetti; Otopteropus cartilagonodus and Pipis- trelhis javanicus were the only bats recorded de- spite an intensive netting effort. The overall body form of Archboldomys mus- seri is similar in most respects to ^4. luzonensis and indicates ground-dwelling habits. However, the smaller, more delicate feet and digits and lon- ger tail of the new species suggest a greater ten- dency toward above-ground as opposed to semi- fossorial activity. Discussion Phylogenetic Relationships The discovery of new species and additional specimens of taxa that have been poorly repre- sented allows us to reassess the definitions of Cru- nomys and Archboldomys and their relationships to other Philippine murids. Musser (1982) distin- guished Archboldomys from Crunomys with a combination of external, cranial, and dental traits. These have changed somewhat as a result of this study. Some of the features in the original diag- nosis of Archboldomys (elongate claws on the front feet, the presence of an alisphenoid strut, and slender mandibles) are no longer diagnostic because they are shared by Crunomys suncoides. Others (upturned nasal tips, elongate incisive fo- ramina, long incisors, large sphenopterygoid va- cuity, and absence of cusps t3 and t9 on the first upper molar) are not shared by A. musseri and therefore are diagnostic for A. luzonensis only. The remaining characters listed by Musser remain diagnostic, and they clearly define Archboldomys as a distinct genus. These are summarized as char- acters 1 through 8 in the brief generic account given above. In describing Crunomys celebensis, Musser (1982) posed an alternative hypothesis that the morphological similarities between Crunomys- like mice of the Philippines and Sulawesi might represent convergence between independent groups. Crunomys celebensis differs from the Philippine Crunomys in many important respects, although all taxa share several characters that are presumed to be derived (Musser, 1982; this study). The discovery of C. suncoides, which shares some additional traits with C. celebensis (soft pelage, small molars, relatively narrow braincase), reduces the magnitude of difference. Other characteristics of the new species further expand the morphological range of the genus. The principal obstacle in determining relation- ships of Crunomys and Archboldomys to other na- tive Philippine murines is that both genera retain many primitive features (Musser, 1982; Musser & Heaney. 1992). They share the following derived morphological characters: (1) tail shorter than the head and body length. (2) elongate hind feet with small plantar pads. (3) reduction in size and num- ber of molar cusps. (4) fusion of cusps on anterior half of first lower molar, and (5) reduced size and simplification of third upper and lower molars. These characters are shared also with the genera Chrotomys, Celaenomys, and Rhynchomys, and to a lesser extent Apomys, and they therefore serve to unite a sizable group of "old endemic" Phil- ippine murids (Musser & Heaney, 1992). Whereas these other genera are characterized by additional unique specializations (Musser & Heaney, 1992), there are no clearly derived morphological traits 22 FIELDIANA: ZOOLOGY uniting Cninomys and Archboldomys as a distinc- tive group. There are similarities in shape, relative size, and general cusp patterns of molar teeth, but this may reflect dietary convergence. Chromosomal data also support some broader relationships among old endemic Philippine gen- era. Chrotomys and Rhynchomys have very simi- lar if not identical standard karyotypes (Rickart & Musser, 1993), supporting the hypothesis that these morphologically specialized shrew-rats are close relatives (Musser & Heaney, 1992). There has been considerable chromosomal evolution within Apomys, but features of some karyotypes support a broader grouping of this genus with Chrotomys and Rhynchomys (Rickart & Musser, 1993; Rickart, unpubl. data), as hypothesized by Musser and Heaney (1992). Our results demonstrate substantial chromo- somal differences between Cnmomys suncoides and Archboldomys hizonensis. Both taxa have low fundamental numbers, but they are otherwise dis- similar and differ from other Philippine murines, which have fundamental numbers of 50 and above (Rickart & Musser, 1993). Among Indo- Austra- lian murine rodents that have been karyotyped, very few exhibit fundamental numbers below 45 (Rickart & Musser, 1993, p. 22, fig. 8). Cnmomys suncoides resembles species of Cremnomys from peninsular India (2N = 36; FN = 36-37; Gadi & Sharma, 1983) in possessing a complement of 36 telocentric elements. However, this similarity is probably coincidental because there are no obvi- ous morphological features linking Cnmomys with the long-tailed, scansorial Cremnomys. To date, there have been no cladistic analyses of re- lationships based on morphology, karyology, bio- chemical genetics, etc.; such studies are clearly needed. Biogeography and Ecology Cnmomys is unique in being the only murid genus endemic to both Sulawesi and the Philip- pines (Musser, 1982). Most of the species have very limited known ranges, but this may be an artifact of their scarcity in collections. Despite the fact that it is represented by only 10 specimens, Crunomys melanhis has an exceptionally broad range. In addition to a relatively wide distribution on Mindanao, it is also represented on the Min- danao land-bridge island of Leyte, as well as the more isolated (but nearby) oceanic island of Ca- miguin (Fig. 1). Among the 15 murid species on Mindanao, only Cnmomys melanius and Rattiis everetti occur on more than one Pleistocene island (Musser & Heaney, 1992; Heaney et al., 1997). The unusually broad range of Crunomys me- lanius may reflect a general relationship between geographic and elevational distributions within Philippine murids. Most species are restricted to mid- or high-elevation montane and mossy forest habitats and are limited geographically to no more than one of the Pleistocene land-bridge island groups (Heaney, 1986; Heaney & Rickart, 1990). This is true for both species of Archboldomys as well. In contrast, Crunomys principally occurs in low-elevation habitat. Nearly all specimens of Crunomys have been found in lowland diptero- carp and lower montane forest habitats below 1500 m elevation; C suncoides is the only species known to occur at higher elevations. Broad geo- graphic range is apparent in a few other Philippine murids that occur at low elevations. Rattus ever- etti has a very broad elevational range that in- cludes lowland dipterocarp forest, and it is the most widely distributed native rodent in the oce- anic Philippines, occurring on most of the major island groups (Heaney & Rickart, 1990; Heaney et al., 1997). Chrotomys mindorensis is a low- elevation species found on two Pleistocene is- lands, Mindoro and Luzon (Rickart & Heaney, 1991). Occurrence at low elevations may promote broader geographic distribution in these taxa by facilitating dispersal across land-bridge islands during periods of lower sea level (Heaney, 1986) or by increasing the likelihood of over-water raft- ing to more isolated islands (perhaps during the frequent regional typhoons). Acknowledgments We thank the following individuals for assis- tance with fieldwork: Ronald Altamirano, Nonito Antoque, Troels Christensen, Andy Dans, Arvin Diesmos, Renato Fernandez, J. C. Gonzalez, Pe- dro Gonzalez, Steven Goodman, Morten Hee- gaard, Arne Jensen, Myrissa Lepiten, Torben Lund, Aldrin Mallari, Arturo Manamtam, Henrik Mouritsen, George Palaya, Town Peterson, George Reyes, Douglas Samson, David Schmidt, Alice Tabaranza, Leoning Tag-at, and Ruth Ut- zurrum. Permits and logistical support were pro- vided by the Protected Areas and Wildlife Bureau (Philippine Department of Environment and Nat- ural Resources, DENR), with special thanks to RICKART ET AL.: REVIEW OF CRUNOMYS AND ARCHBOLDOMYS 23 Angel Alcala, Jean Caleda. Edgar Canete. Carlo Custodio, and Marlynn Mendoza. Paula Jenkins graciously provided photographs of the skin and skull of the holotype of Cnowmys fallax. Scan- ning electron micrographs were made by Edward King. Sarah George. Guy Musser. Luis Ruedas. and Robert Timm reviewed the manuscript and provided constructive comments. Financial sup- port was provided by the U.S. National Science Foundation (grant no. BSR-85 14223). the Smith- sonian Institution, the World Environment and Resources Program of the John D. and Catherine T. MacArthur Foundation, the Ellen Thorne Smith Fund of FMNH. the Aage V. Jensen Charity Foun- dation, the Danish Ornithological Society, and Birdlife International. Literature Cited Daneelsen, F, D. S. Balete. T. D. Christensen. M. Heegaard. O. F Jakobsen. A. F Jensen, and M. K. PouLSEN. 1994. Conservation of Biological Diversity in the Sierra Madre Mountains of Isabela and Southern Cagayan Province, the Philippines. Birdlife International. Zoological Museum of Copenhagen University, and Danish Ornithological Society. Co- penhagen and Manila, 146 pp. Gadi. I. K.. AND T. Sharma. 1983. Cytogenetic rela- tionships in Rattus. Cremnomys. Millardia. Nesokia and Bandicota (Rodentia: Muridae). Genetica. 61: 21- 40. Heanev, L. R. 1986. Biogeography of the mammals of Southeast Asia: Estimates of colonization, extinction, and speciation. 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