OCCASIONAL PAPERS OF THE CALIFORNIA ACADEMY OF SCIENCES No. 36, 12 pages, 7 figures, 1 plate- January 28, 1963 REMARKS UPON THE NATURAL HISTORY OF GERRHONOTUS PANAMINTINUS STEBBINS By Benjamin Harrison Banta Research Biologist, California Academy of Sciences Field work in the Saline Valley hydrographic basin, Inyo County, Cali- fornia, during 1959 and 1960, resulted in the collection of a large number of reptiles, among which were six specimens of the rare Panaraint alligator liz- ard, Gerrhonotus panamintinus Stebbins (1958). These records extend the known geographic range altitudinally and latitudinally and provide additions to the knowledge of seasonal activity, habitat distribution, reproduction, par- asitism, color variation, and external morphological variation. Materials and Methods The specimens reported upon herein were obtained in buried-can "pit- fall" traps (Banta, 1957) and are now deposited in the herpetological collec- tions of the California Academy of Sciences. The traps were setout according to the automobile speedometer and with no regard to particular environmental situations. It is believed that this method afforded an opportunity to obtain a random sampling of the entire small-sized terrestrial fauna, including arthro- pods, reptiles, and mammals. Collecting Stations Specimens of Gerrhonotus panamintinus were taken at two general areas in the Saline Valley hydrographic basin; 1) Nelson Mountains, Grapevine Canyon; and 2) on the east slope of the Inyo Mountains, on the north side of Daisy Canyon. CALIFORNIA ACADEMY OF SCIENCES (Occ. Papers % ^•^r\i4:- f-t y >A-- « Figure 1. Distribution of Gerrhonotus panamintinus Stehh'vTiS. (1) Surprise Can- yon. Panamint Mountains (type locality); (2) Nelson Mountains, Grapevine Canyon; (3) Inyo Mountains, Daisy Canyon. Photograph of U. S. Geological Survey Ballarat Quadrangle by Maurice Giles. No. 36) BANTA: GERRHONOTUS PANAMINTINUS STEBBINS Figure 2. Nelson Mountains, Grapevine Canyon. Elevation 5100 feet. Station 11 (left) and station 12 (right). March 1959- These two stations were adjacent to one another, and were the only ones that were not at least 0.2 of a mile apart in Grape- vine Canyon. An adult female of Gerrhonotus panamintinus was trapped in a buried can and collected on September 16, I960 at Station 12. It is interesting to note that in this particular instance where there was a mesic environment on one side of the road and a xeric situation on the other, the specimen of G. panamintinus was obtained in the latter, a phenomenon which was not anticipated. I. Nelson Mountains, Grapevine Canyon Elevation 4000 to 6000 feet. Twenty-five "pitfall" trapping stations, consisting of four containers each, were set out, usually at 0.2 mile intervals along the dirt road descending into Saline Valley. Of the 25 stations, speci- mens of G. panamintinus were collected at the following four: Station 12. (Figure 2.) Elevation 5100 feet. This site is situated across the dirt road from Station 11 which somewhat resembles the type lo- cality of the species at Surprise Canyon, Panamint Mountains, being charac- terized by a tree and shrub flora dominated by willows (Salix laevigata and S. lasiolepis), virginsbower (Clematis lugusticifolia), and wild grape (Vitis Girdiana). The immediate environment of the station around which four "pit- fall" traps were set was covered with low desert shrubs. Reptiles obtained in (or near *) the traps at this station included Sceloporus oddi^entalis lon- gipes (7) ' ; Uta stansburiana stansburiana (7); Cnemidophorus tigris tigris 1/ Numbers in parentheses refer to specimens in the collections of the California Academy of Sciences. CALIFORNIA ACADEMY OF SCIENCES (Occ. Papers (4); Gerrhonotus panamintinus (1); *Crotalus mitchelli stephensi (1); *Salva- dora hexalepis mojavensis (1). Station 13- (Figure 3-) Elevation 5000 feet. The environment at this site contained a flora indicating more xeric conditions than at Station 12. Rep- tiles collected at this station included Sceloporus occidentalis longipes (9); Vta stansburiana stansburiana (14); Cnemidophorus tigris tigris (17); Eume- ces gilberti rubricaudatus (3); Gerrhonotus panamintinus (1). Station 14. (Figure 4-) Elevation 5000 feet. Xeric vegetation. Reptiles collected v/ere Sceloporus occidentalis longipes (2); Uta stansburiana stans- buriana (7); Cnemidophorus tigris tigris (1); Eumeces gilberti rubricaudatus (5); Gerrhonotus panamintinus (1). Station 16. (Figure 5-) Elevation 4850 feet. The environment at this station was similar to that described by Stebbins (1958, pp. 11-12) for the type locality of G. panamintinus in Surprise Canyon. Salix laevigata, S. lasio- lepis, Clematis lugusticifolis, and Vitis Girdiana were the dominant tree and shrub cover, affording a relatively lush situation in comparison to the surround- ing hillsides. Reptiles collected included Sceloporus occidentalis longipes Figure 3- Nelson Mountains, Grapevine Canyon. Elevation 5000 feet. Station 13. March 1959- Four buried can "pitfall" traps were located on a line on the left side at the base of large basalt boulders. An adult male of Gerrhonotus panamintinus was found dead in a buried-can trap on May 7, I960. No. 36) BANTA: GERRHOMOTUS PANAMINTINUS STEBBINS (4); Cnemidophorus tigris tigris (2); Eumeces gilberti rubricaudatus (13); Ger- rhonotus panamintinus(2). The usually omnipiesent Via starts buriana was con- spicuous by its absence. Other stations in Grapevine Canyon, which vegetationally closely re- sembled the type locality in Surprise Canyon, but which did not yield speci- mens of G. panamintinus, were Station 9 (elevation 5320 feet). Station 16A (elevation 4860 feet), Station 21 (elevation 4480 feet), and Station 25 (eleva- tion 4030 feet). However, each of these stations did yield a moderate number of specimens of Sceloporus occidentalis longipes and Eumeces gilberti rub- ricaudatus. ,*^A^i *e^Mi <^f^^ Figure 4. Nelson Mountains, Grapevine Canyon. Elevation 5000 feet. Station 14. March 1959- "Pitfall" traps were located in the gravelly alluvium at the base of the piled boulders. A young adult male of Gerrhonotus panamintinus was obtained here on June 14, I960. See plate 1 (CAS 89675)- II. Inyo Mountains, Daisy Canyon A series of "pitfall" trapping stations, consisting of two cans per sta- tion, were set out along a little-used path ascending the relatively bare and steep slope of the Inyo Mountains along the north ridge of Daisy Canyon. This area was immediately to the north of the abandoned tramway, which for some years had transported salt in metal buckets from deposits in the center of Sa- line Valley westward over the steep Inyo Mountains to a railroad siding at CALIFORNIA ACADEMY OF SCIENCES (Occ. Papers Keeler, Owens Valley. Out of a total of 30 stations, only one produced a spe- cimen of G. panamintinus . .-:^r-.i; Figure 5. Nelson Mountains, Grapevine Canyon. Elevation 4850 feet. Station 16. The environment viewed from the south as it appeared in May 1959. This station closely resembles that of the type locality for Gerrhonotus panamintinus in Surprise Canyon, Panamint Mountains. Two specimens were obtained here; an adult female on May 2, 1959, and an adult male on June 10, I960. See plate 1 (CAS 89676). Station 125- (Figure 6.) Elevation 4000 feet. Granite boulder talus. This site was by far the most arid one sampled which yielded alligator liz- ards. The flora immediately surrounding the area was composed of the follow- ing shrubs; Atriplex canescens, Arenaris macrodenia, Brickelia atraclyoides, Chrysothamnus teretifolius, Encelia spp., Grayia spinosa, Gallium stellatum, Menodora spinescens, and an undetermined perennial bunch grass. The cacti Opuntia basilaris and Echinocactus acanthodes, and a creosote bush, Lanea divaricata, were growing nearby. No other reptiles were collected at Station 125, although a worm snake, Leptotyphlops humilis, was obtained in a can at an adjacent (lower) station (Station 124; elevation 3900 feet). Of the two five quart cans set out in the talus at Station 125, one was pushed aside by a mi- nor rock slide at the time the specimen of G. panamintinus was obtained on June 11, 1959. No. 36) BANTA: GERRHONOTUS PANAMINTINUS STEBBINS Figure 6. Inyo Mountains, Daisy Canyon. Elevation 4000 feet. Station 125. This is the most xeric environment at which a specimen of Gerrhonotus p anamintinus was obtained. A large adult male was collected on June 11, 1959 io a five-quart can set out in the talus. See plate 1. General Remarks The discovery and description of the Panamint alligator lizard is with- out doubt the most remarkable herpetological find within the Great Basin for a considerable number of years. It is indeed interesting that such a distinct form should have rem.ained unknown until recently. Stebbins (1958, p. 15) commented that G. panamintinus "is closely re- stricted to the vicinity of water. ...The greatest distance from water at which a specimen was found was 30 feet. All sites of capture were well shaded, and there was damp soil at or within a few feet of the place of capture." Only two specimens captured in Grapevine Canyon, at Station 16, were from a well shaded, damp area, and even there, there was no open water. The spe- cimen from Daisy Canyon, Inyo Mountains, was from an extremely arid envi- ronment. Equally hydrophilic organisms such as land snails occur under rocks and boulders of talus slopes in otherwise xeric situations. Thus G. panamin- tinus is not exclusively restricted to moist situations, and does move great distances from water into rather arid situations. Stebbins (1958, p. 10) also stated that "..the Surprise Canyon popula- tions could not be connected with populations that might exist in other can- yons." The collection of G. panamintinus from arid situations at Station 125 8 CALIFORNIA ACADEMY OF SCIENCES (Occ. Papers in the Inyo Mountains and the more xeric Grapevine Canyon stations suggests that connections between the populations in many of the canyons is not only possible, but must actually exist. The seasonal occurrence of G. panamintinus based upon all known sam- ples (including the holotype and paratypes)is shown on table 1. May and June are probably the periods of greatest sexual activity. One adult female (CAS 88135), obtained on May 1, 1959, contained twelve developing eggs, three of which were 2.4 mm. in diameter; the remaining nihe ranged from 3.4 to 4.4 mm. in diameter. The excessive heat of July and August probably induces thermal aestivation. Two lizards mated in captivity in May 1961 (Banta and Leviton, 1961). Table 1. Seasonal occurence of Gerrhonotus panamintinus Month Total number of specimens obtained Males Females Juveniles April 1 May 2 June 6 July 0 August 0 September 1 1 2 2 Stebbins (1958, p. 15) remarked that "the behavior of the type specimen in captivity suggests that the lizard is a good climber." Three specimens (plate 1, lower figure) kept alive in a glass terrarium with several twigs angl- ing up against the walls, were often observed either climbing or perched upon the twigs. These same three captive specimens were also observed digging into the same bottom of the terrarium, and occasionally observed lying almost totally covered by sand. Of the three specimens obtained alive in 1960, one was sacrificed for experimental purposes and the other two died from heavy infestation of mites after living captivity for almost a year. Gerrhonotus panamintinus probably has a wider distribution in the des- ert mountain ranges adjacent to the Inyo and Panamint mountains than current records indicate (figure 1), and likewise an even greater distribution during the various moist Pluvial periods of the Pleistocene. During the last Pluvial period which ended approximately 11,000 years ago (Broecker, 1957), clima- tic conditions were probably more favorable for its occurrence at much lower elevations. Since the climate has become more arid, it has survived only in No. 36) BANTA: CERRHONOTUS PANAMINTINUS STEBBINS to z LiJ o Ul a. MVZ 65 405 M VZ 65 409 CAS 8 9676 CAS 89 675 M VZ 65 405 M V 2 M V Z 6 5 407 C AS 8BP36 CAS 892 30 CAS 89677 3800 4000 4500 4800 EL E VATION IN FEET 5000 5100 Figure 7. Altitudinal distribution of Gerrhonotus panamintinus. the more favorable environments found in the more mesic canyons and talus slopes of the higher mountain ranges. More exact knowledge of the present range would provide further evidence to understand the probable distribution of the G. panamintinus during Pluvial times, and the subsequent migrations and retreats since the close of the last Pluvial period. However, the difficul-fy^ in obtaining samples of this species encountered by Stebbins (1958), and the author, cannot be minimized. Since many of the areas in the desert mountain ranges, where it is likely to occur, are relatively inaccessible except by pack- animal or four-wheel-drive vehicle, the determination of distributional limits may not be accomplished for some time to come. The lizard obtained on the eastern slope of the Inyo Mountains at Sta- tion 125 is remarkable not only for the fact that it was obtained from an ex- tremely arid locality, but also because it is the only adult of G. panamintinus obtained to date having a perfect tail; i.e., non-regenerated (plate 1, upper figure). This specimen was sent alive to Dr. Robert C. Stebbins, Museum of Vertebrate Zoology, University of California, Berkeley, and was thriving on a specially enriched meal-worm diet at the time of this writing. The specimens of G. panamintinus obtained during the 1959-1960 field studies extend the range of this species from the type locality at Surprise Can- yon, Nelson Mountains, and Daisy Canyon, Inyo Mountains (figure 1). The al- titudinal distribution of the currently known specimens of G. panamintinus is summarized in figure 7. Gerrhonotus panamintinus appears to occur in certain desert mountain ranges in a narrow band, ranging in altitude from 3800 to 5100 feet, in more diverse and more arid environmental situations than previously known. External morphological variation of the specimens examined is shown on table 2. Variation in dorsal color pattern is demonstrated by plate 1. Gerrhonotus panamintinus is morphologically close to G. multicarinatus and was most likely derived from it. Since many of the Great Basin valleys were inundated with water to form lakes of varying sizes during the Pleisto- cene (Hubbs and Miller, 1948), with the effect of a more moist climate, it is 10 CALIFORNIA ACADEMY OF SCIENCES (Occ. Papers Table 2. External Morphological Variation in Gerrhonotus Panamintinus from Saline Valley Hydrographic Basin Station Number 12 13 14 16 16 125 CAS Number 89677^'^ 89230 89675^/ 88135 89676 MVZ^/ Sex Female Male Male Female Male Male Dorsal Transverse Bands on Trunk 8 8 8 8 10 8 Dorsal Scale Rows: Transverse 49 49 47 48 47 47 Longitudinal 15 14 14 14 14 16 Longitudinal Rows Keeled 11 11 12 11 11 11 Ventral Scale Rows: Transverse 45 45 45 44 44 45 Longitudinal 12 12 12 12 12 12 Gulars 21 20 21 20 20 20 Labials: Upper 12 11 11 11 11 11 Lower 10-12 10 10 10 10 10-11 Measurements: (in mm.) Snout-vent Length 110 103.5 92 112 122 119 Tail Lenght 102 116 127 87 151 207 r3/62 R 79 R42 R 57 R 70.5 Axilla-Groin Distance 64 55 51 58 62 62 Head Width 13 14.3 12.1 15 20.1 18 Snout-Ear Distance 21.7 22.4 20.3 21.8 26 22 Foreleg 27 28.5 27.5 26 29 32 Hindleg 30 33 32 33.6 37 38 2/ 3/ Measurements taken while lizard was alive. R = regenerated portion of tail. Plate 1 Upper figure. Adult male collected at north side of Daisy Canyon, Inyo Mountains, Sta- tion 125. Elevation 4000 feet. June 11, 1959- This is the only specimen in which the tail was not regenerated. Photograph by Dr. Nathan Cohen. Lower figure. Color variation within 3 living specimens from Grapevine Canyon, Nel- son Mountains. June and September, I960. Top to Bottom, CAS 89676 male [Station 16, elevation 4850 feet]; CAS 89675 male [Station 14, ele- vation 5000 feet]; CAS 89677 female [Station 12, elevation 5100 feet]. Photograph by Dr. W. I. Follett. OCC. PAPERS CALIF. ACAD. SCI., NO. 36 (BANTAM PLATE 1 No. 36) BANTA: GERRHONOTUS PANAMINTINUS STEBBWS 11 not inconceivable that a distributional connection between the populations of (7. panamintinus in the Inyo and Panamint mountains and the other western Great Basin ranges existed with populations of G. multicarinatus which now occur under xeric conditions on the north slope of the San Bernardino and San Gabriel mountains. Gerrhonotus panamintinus seems more closely related to the gerrhono- tine group which includes G. multicarinatus of west central and southern Cal- ifornia, G. cedroensis from Cedros Island, Baja California, and G. paucicari- natus from the Cape region of Baja California, than to G. kingi of southern Arizona and the adjacent Mexican mainland. This, if true, would support a hy- pothesis that there are three primary centers of origin for the existing reptile fauna of western North America, west of the Rocky Mountains. A significant number of the nominal species within the Colorado drainage of Arizona were probably derived from progenitors in what is now the state of Sonora, Mexico, and the Mexican Plateau, and a number of the nominal reptile species in south- ern California and the western Great Basin region were derived from progeni- tors in peninsular Baja California, Mexico, and the Mexican Plateau. Acknowledgments Partial support for this study was provided by grants from the American Association for the Advancement of Science— California Academy of Sciences, and the National Science Foundation. I am deeply indebted to the following students from Pomona College, Claremont, California, who assisted during the field phase of the program; David Armstrong, Harry Coulombe, Emery Zim- merman, Clarence Sasaki, Gary Hendrix, and Richard Young. Mr. France Cou- lombe of Santa Monica, California, assisted on many of the field trips. Drs. Miles McCarthy and Yost U. Amrein assisted in obtaining support from the De- partment of Zoology of Pomona College. Assistance in the determination of the plant species was generously given by Dr. Lyman Benson, Department of Botany, Pomona College; Dr. John Hunter Thomas, Division of Systematic Biology, Stanford University; and Mr. John Thomas Howell, Department of Botany, California Academy of Sciences. To Dr. Nathan Cohen, Biology Department, Modesto Junior College, and to Dr. W. I. Follett, Department of Ichthyology, California Academy of Sciences, I am deeply indebted for their excellent color photographs. Dr. Alan E. Leviton, Department of Amphibians and Reptiles, California Academy of Sciences, has read the manuscript and I am very grateful for his many helpful suggestions, and for ^^^^^^ figure^^ Dr. G Dallas Hanna, Curator, Department of Geology, provided critical advice and assistance and is responsible for the remarkable reproductions of the color photographs (plate 1). lam deeply grate- ful to Mr. Maurice Giles for figure 1 and for making the prints for figures 2 through 6. Miss Lynn Connelly not only typed the manuscript, but also made many valuable suggestions. 12 CALIFORNIA ACADEMY OF SCIENCES (Occ. Papers Literature Cited Banta, Benjamin H. 1957. A simple trip for collecting desert reptiles. Herpetologica, vol. 13, pp. 174-176. Banta, B. H., and Alan Edward Leviton I96I. A note on the mating behavior of the Panamint alligator lizard, Gerrho- notus panamintinus. Herpetologica, vol. 17, pp. 204-206, fig. 1. Broecker, Wallace S. 1957. Evidence for a major climatic change close to 11,000 years B.P. Bul- letin of the Geological Society of America, vol. 68, pp. 1703- 1704 (abstract). HuBBS, Carl L., and Robert R. Miller 1948. The Great Basin with emphasis on glacial and postglacial times. II. The zoological evidence. Bulletin of the University of Utah, vol. 38, no. 2, pp. 18-166. Stebbins, Robert C 1958. A new alligator lizard from the Panamint Mountains, Inyo County, Cal- ifornia. American Museum Novitates, no. 1883, 27 pp.