Great Basin Naturalist

Volume 38 | Number 4 Article 4

12-31-1978 New range and a new subspecies for the Eridiphas slevini John R. Ottley Brigham Young University

Wilmer W. Tanner Brigham Young University

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Recommended Citation Ottley, John R. and Tanner, Wilmer W. (1978) "New range and a new subspecies for the snake Eridiphas slevini," Great Basin Naturalist: Vol. 38 : No. 4 , Article 4. Available at: https://scholarsarchive.byu.edu/gbn/vol38/iss4/4

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. NEW RANGE AND A NEW SUBSPECIES FOR THE SNAKE ERIDIPHAS SLEVINI

John R. Ottley' and Wilmer W. Tanner'

Abstract.— Additional specimens of Eridiphas slevini from Baja California del Sur are reported and discussed

and the first specimen from Baja California del Norte is reported. Specimens from San Marcos Island are distin-

guished from mainland stock with the description of the new subspecies E. s. marcosensis.

Of the few reported specimens of Eri- Ignacio. A juvenile male (BYU 34651), was diphas slevini (Tanner), most have been taken S Santa Rosalia, 2.2 miles W the vil- taken in the Cape region of Baja Cahfornia, lage of Santa Agueda on 14 June 1978 at including Cerralvo Island. Tanner (1943) in 2140 hours as it was foraging along a his description of the species Hijpsiglena streambed at the base of an aqueduct. slevini, stated that the holotype (CAS A specimen of E. slevini was recently dis- 53631) was collected at Puerto Escondido in covered near Bahia de los Angeles, Baja Baja California by Joseph R. Slevin on 14 California del Norte. This specimen, a juve- June 1921. A second specimen (CAS 86093) nile male (BYU 36415), was collected as it was collected in January 1959 by Dr. Alan lay coiled in a small basal fissure of a boul- E. Leviton and Mr. Hugh B. Leech from a der in a dry and narrow, rock-strewn wash, rivulet in the El Saltito Arroyo, 12 miles about 0.5 miles north of the paved road at east of La Paz (Leviton and Tanner 1960). a point 9.2 miles (by road) west of the re- Soule (1961) reported the occurrence of the sort at Bahia de los Angeles. species on Cerralvo Island, the specimen It is of interest to note that although a (CAS 88985) having been collected on 6 number of additional specimens have been March 1960 by Dr. Michael E. Soule and collected from various locations in the Cape Mr. Robert Crippen (Etheridge 1961). region since the last specimen was reported Specimens remain scarce in collections, by Soule (1961), none have reached the lit- but recent field work has produced a series erature. Of three specimens on hand at the from a wide geographical area, including San Diego Society of Natural History Mu- the San Ignacio-Santa Rosalia area of Baja seum, two were collected north of Cabo California del Sur. San Lucas at Rancho La Burrera (SDSNH

Specimens from this area are, first, an 45032) and La Burrera of La Laguna adult female (BYU 33672) taken alive on 26 (SDSNH 45213) in August 1961 and Sep- August 1977 at 2300 hours, 17.1 miles (by tember 1965, respectively, by Mr. Trinidad

Mexican Highway 1) NW Santa Rosalia. A Castillo and Mr. A. Agundes. The third second adult female (CAS 146498) was col- specimen (SDSNH 46051) was collected at lected on 14 September 1977, 18 miles (by Rancho Fragua in Arroyo Fragua, 15 miles

Mexican Highway 1) NE Santa Rosalia by northwest of Loreto on 2 October 1967 by Robert L. Seib. Two additional adult female Mr. Reid Moran. Before the range extension specimens (CAS 146499 by R. L. Seib and to San Ignacio, the locality for SDSNH BYU 34618) were collected 7.6 miles (by 46051 had, in all probability, been the most

Mexican Highway 1) on 7 May 1978 and northerly point known for the species. A

7.0 miles (by Mexican Highway 1), 2130 juvenile female specimen (BYU 34652) col- hours on 7 June 1978, respectively, E San lected between Loreto and Puerto Escon-

'Life Science Museum, Brigham Young University, Provo. Utah 84602.

406 December 1978 Ottley, Tanner: Snake Distribution 407

dido at the fishing village known as Junca- on the midventral line, surrounding the hto on 20 June 1978 at 2145 hours may be mental and wedging posteriorly between from the same arroyo as the specimen col- the anterior pair of genials; genial size mod- lected by Slevin in 1921. Another specimen erate, posterior pair slightly more elongate (CAS 134804) is an adult male collected S than anterior pair, the first five infralabial La Paz, 3 km S San Bartolo on 1 July 1972 pairs contacting anterior genials, the fifth by Ted Papenfuss. and sixth pairs in contact with posterior The range of E. slevini is now known to genials; three gulars between posterior gen- include Danzante Island. That specimen ials and first ventral. (CAS 140097) is an adult female collected Dorsal pattern consists of five longitudi- during July 1974 by Steven Strand. nal rows (six rows at midbody) of dark gray- Included with the material from the San brown spots on a brown-gray ground color, Ignacio-Santa Rosalia area are two speci- dorsal rows on body of 65 spots, 28 on tail, mens from San Marcos Island. Both were some of which are divided or partially di- collected in the large Arroyo de la Taneria vided at the dorsal midline, each spot in- adjacent to the gypsum mine on the island volving 13 to 20 scales, center of spots by one of us (JRO). These specimens con- lighter than margins; lateral spots smaller, stitute a new insular record and bear char- involving 1-5 scales all dark gray-brown; acters which distinguish them from the scales involved in ground color have light presently known mainland stock. colored edges, scales between middorsal spots being lightest. Nape pattern composed of five spots; a Eridiphas slevini marcosensis, subsp. nov. median spot 4 scales long and about 2.5 HoLOTYPE.- BYU 34617, an adult female scales wide, separated from parietals by a collected from a talus slope on the south single scale, two round spots at each side of side of Arroyo de la Taneria on San Marcos median spot involve 12 to 13 scales each, Island at 2130 hours on 18 June 1978. two posterior nape spots are elongate and Paratype.- BYU 34616 an adult female in line with spots on dorsal midline, sepa- collected from a flat wash near the goat rated from one another by a single row of corrals in Arroyo de la Taneria at 2155 light-edged scales and from anterior nape hours on 2 June 1978. spots by 1-1.5 scales. Elongate lateral spots Diagnosis.— A subspecies closely related begin on the last supralabial and last two to and apparently derived from the main- infralabials, pass under anterior nape spots the posterior land Eridiphas slevini, from which it can be upward to and separated from distinguished in having a greater number of nape spots (by less than one scale); a post- ventral scales, dorsal blotches, and small ocular stripe extends from orbit through head size. lower postocular to reach mouth on the 6th Description of holotype.— An adult fe- and 7th supralabials; supralabials are cream gray-brown spots male, total length 467 mm, tail 83 mm, colored with small dark head 17.5 mm, snout length 4.5 mm, diame- on anterior-posterior edges, infralabials are parietals, fron- ter of orbit 3.0 mm; ratio of tail length to similar with less dark color; total length 17.95 percent, head into body tal, and supraoculars have fine irregular 4.56 percent. dark gray-brown blotches; gulars, lateral finely Scale rows on body 21-23-19, on the tail edges of ventrals and subcaudals ventrals and at the 15th subcaudal 6 rows; ventrals 200, flecked, chin shields, central of subcaudals 61, anal divided; supralabials 8- subcaudals are immaculate yellow-gray. similar to 8, infralabials 10-10; preoculars 2-2, upper Variation.— Single paratype preocular 3 times longer than lower; post- holotype in nearly all details. Color pattern oculars 2-2 with parietals in contact with slightly faded yet discernable. Ventral count ventral lower, temporals 1-1-2, loreals 1-1, nasal lower, with 198, but higher than specimens. Tail in- divided, rostral wider (3.1 mm) than high counts for mainland (1.3 mm); 14 maxillary teeth. complete, with only 23 subcaudals. Tempor- scale between First pair of infralabials in broad contact als 2 -I- 2 due to a small 408 Great Basin Naturalist Vol. 38, No. 4

each large primary temporal and 6th supr- However, subcaudals are well within the alabials. Head to body ratio 4.69 percent given range and head to body ratios for E.

(4.56 percent in holotype). This ratio in- s. marcosensis and the Cerralvo Island spec-

dicates a smaller head size in E. s. marco- imen are similar. sensis (Table 1). Several specimens bear peculiarities dem- Size.— Eridiphas slevini is small to mod- onstrating a certain amount of genetic erate in size; the largest specimen measured plasticity. The Danzante Island specimen is

from the penninsula is 562 mm in total more darkly colored than other specimens length, 102 mm for the tail and a snout- seen and its pattern is indistinct, a character vent length of 460 mm (SDSNH 45213). also observed in the paratype of E. s. mar- The smallest specimen is 213 mm in total cosensis. One specimen from near San Ig- length, 40 mm for tail (CAS 53631). The nacio (CAS 146499) does not bear the pa-

paratype for E. s. marcosensis (BYU 34616) rietal-lower postocular contact characteristic

is the largest specimen measured, having a of the . The separation is caused by snout-vent length of 481 mm and with a to- what appears to be the formation of an ex- tal length of 524 mm; however, more than tra scale of minute proportion from the half of the tail is missing, with only 43 mm lower fold of each parietal. Also the anal

remaining. plate is divided twice to form three parts. Remarks.— The data presented in Table 1 The specimen from near San Bartolo (CAS indicate a trend for a higher number of 134804) has heavy nuchal blotches similar ventral and subcaudal scutes toward the to Hypsiglena and a low count for dorsal north. The exceptions are BYU 34651 from scales of 21 rows. The specimens from La Santa Agueda, with a low count of 182 ven- Burrera (SDSNH 45032 and SDSNH 45213) trals, and SDSNH 46051 from near Loreto, also bear lower dorsal scale counts, with 22 with a high count for the Cape Region of and 21 rows respectively. 192 ventrals. The most variable characters appear to be counts for ventrals, subcaudals, Discussion and dorsal blotches, and head to body ra- tios. Temporal formulas appear to be of The new material from the San Ignacio- little value because a random variation is Santa Rosalia area extends the range of Eri- seen throughout the range. There is no diphas slevini approximately 130 miles overlap between E. s. marcosensis and northward from the area at Puerto Escon- mainland stock involving ventral counts, the dido given by Leviton and Tanner (1960). number of dorsal blotches, and head size. The Bahia de los Angeles specimen repre-

Table 1. Variations in scale counts, body blotches, body proportions, and ratios of Eridiphas slevini'. December 1978 Ottley, Tanner: Snake Distribution 409

sents an additional northerly extension of possible occurrence of Eridiphas in more nearly 100 miles. Northerly progression northerly areas than those localities present-

probably occurred along the eastern third of ly known. It is interesting to note as well, the peninsula, avoiding the more barren the discovery of the recently described Viscaino Desert to the west. gecko Anarhyhis (Murphy 1974) in southern The possibility must be noted that we California (Fritts, pers. comm.), another in- may be dealing with an isolated population dication that many of the southern forms in the Bahia de los Angeles region even may range well into the north. though BYU 34615 is not significantly dis- tinct. Eridiphas seems to prefer a more tem- The four specimens collected between perate climate as do Lichanura, Elaphe, and San Ignacio and Santa Rosalia were taken Tantilla. Lichanura is not presently known from only two sites along Mexican Highway to have a zone of intergradation, the popu- 1. Populations also occur near Bahia de los lations of the Central Desert and San Ig- Angeles, Loreto, and La Paz. Although nacio being separated by approximately 100 present data are meager, such evidence sug- miles (Gorman 1965, Bostic 1971). Elaphe gests a spotty distribution for E. slevini, a rosaliae occupies a range nearly identical to condition possibly created by competition Eridiphas in Baja California del Sur (Savage pressures imposed by the more recent arriv- 1960). Specimens of Elaphe rosaliae in Baja al of other genera. This idea adds strength California del Norte discovered by Hun- to the hypothesis that E. slevini represents a saker (1967) in Guadalupe Canyon are in- relict form and probable progenitor of the dicatory of a disjunct northern population modern genera Hypsiglena and Leptodeira of that species and presents a clue as to the (Leviton and Tanner 1960).

Fig. 1. Dorsolateral view of Eridiphas slevini marcosensis holotype, BYU 34617 (photo courtesy of John H. Tashjian). 410 Great Basin Naturalist Vol. 38, No. 4

Acknowledgments ico, D. F. Sincere gratitude is expressed to Mr. Antonio Chavez and his wife, whose Fieldwork was partially supported by the warm hospitality during our stay on San Associated Students of Brigham Young Uni- Marcos Island will be long remembered. versity Student Research Fund. Ovir thanks are extended to Mr. Robert W. Murphy and Literature Cited Mr. John C. Cram for their faithful assist- field. ance and company while in the Dr. BosTic, D. L. 1971. Herpetofauna of the Pacific Coast Thomas Fritts of the San Diego Society of of north central Baja California, , with a Natural History Museum and Dr. Alan E. description of a new subspecies of PhijUodac- tijltis xanti. San Diego Soc. Nat. Hist., Trans. Leviton of the California Academy of Sci- 16(10):237-263. enough to loan specimens. ence were kind DuELLMAN, W. E. 1966. Remarks on the systematic Mrs. Gail Olsen and Mrs. Vickie R. Ottley status of certain Mexican of the genus typed the manuscript. Mr. John H. Tashjian Leptodeira. Herpetologica 22(2):97-106. photographed the holotype and furnished Etheridge, R. 1961. Additions to the herpetological fauna of Isla Cerralvo in the Gulf of California, Figure 1. Mr. Brian Hatch prepared the Mexico. Herpetologica 17(l):55-60. map for Figure 2. The Scientific Collecting Gorman, G. C. 1965. The distribution of Lichanttra Permit was provided by Dr. Antonio Land- trivirgata and the status of the species. Herpe- azuri Ortiz, Director General, Fauna Sil- tologica 21(4):283-287. HuNSAKER, D. 1965. The Ratsnake Elaphe rosalie in vestre Departamento de Conservacion, Mex- Baja California. Herpetologica 21(l):71-72. Kelly, K. L. 1958. ISCC-NBS color-name charts illus- trated with centroid colors. National Bureau of Standards, NBS Circular 533. Leviton, A. E., and W. W. Tanner. 1960. The gener- ic allocation of Htjpsiglena slevini Tanner (Ser- pentes: ). Occ. Pop. Calif. Acad. Sci. 27. 7 pp. Murphy, R. W. 1974. A new genus and species of Eu- blepharine gecko (Sauria: Gekkonidae) from Baja California, Mexico. Proc. Calif. Acad. Sci. 40:9.3-109. 1960. Evolution of a peninsular herpeto- Savage, J. M. fauna. In sumposititn: The biogrography of Baja California and adjacent seas. Syst. Zool. 9(3-4): 184-212. SouLE, M. E. 1961. Eridiphas slevini (Tanner) on Cer- ralvo Island, Gulf of California, Mexico. Herpe- tologica 17(1):610. E., a. 1966. Biogeography SouLE, M. and J. Sloan. and distribution of the and amphibians on islands in the Gulf of California, Mexico. San Diego Soc. Nat. Hist., Trans. 14(11): 137-156. Tanner, W. W. 1943. Two new subspecies of Hypsig- lena from western North America. Great Basin Nat. 4:49-54. 1944. A taxonomic study of the genus Htjpsig- lena. Great Basin Nat. 5:25-92.

Cobo San Lucas

Fig. 2. Distribution of Eridiphas slevini on the Baja California peninsula and neighboring islands.