AMERICAN MUSEUM Norntates PUBLISHED by the AMERICAN MUSEUM of NATURAL HISTORY CENTRAL PARK WEST at 79TH STREET, NEW YORK, N.Y
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AMERICAN MUSEUM Norntates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3027, 12 pp., 6 figures November26, 1991 The Lizard Genus Sphenomorphus (Scincidae) in Panama, with Description of a New Species CHARLES W. MYERS1 AND MAUREEN A. DONNELLY2 ABSTRACT Greer assigned three species of Middle Ameri- langeal formulae, and male genitalia. Sphenomor- can skinks to the otherwise Indo-Australian phus cherriei is a widespread skink found at the Sphenomorphus, a plesiomorphic taxon. Sphen- southern limits ofits range on the Pacific lowlands omorphus rarus, new species, extends the New ofextreme western Panama. A smalljuvenile from World range ofthe genus southeastward to the end the Atlantic lowlands also is reported, although its of the Cordillera de Talamanca in western Pana- assignment to cherriei is provisional since it falls ma. The new species is based on a specimen from somewhat outside the range ofvariation ofnearly 780 m in lower montane rain forest. It is most 300 Costa Rican and western Panamanian spec- similar to S. cherriei (Cope) but is readily diag- imens examined. nosed by diverse characters of scutellation, pha- RESUMEN Greer asigno tres especies de escincidos me- 780 metros de altitud en la selva pluvial montana soamericanos a Sphenomorphus, un genero ple- baja. Esta especie es mias parecida a S. cherriei siomorfico por otra parte de la region indo-aus- (Cope) pero parecer a ser diagnostica facilmente traliana. Sphenomorphus rarus, especie nueva, por caracteres diversos de las escamas, f6rmulas extiende la distribucion del genero en el Nuevo de las falanges, y de los genitales masculinos. Mundo hacia el sudeste hasta el final de la Cor- Sphenomorphus cherriei, un escincido amplia- dillera de Talamanca en el occidente de Panama. mente distribuido en America Central, tiene su La especie nueva se basa en un especimen de los limite de distribucion en las tierras bajas del Pa- 1 Curator, Department of Herpetology and Ichthyology, American Museum of Natural History. 2 Boeschenstein Research Fellow, Department of Herpetology and Ichthyology, American Museum of Natural History. Copyright © American Museum of Natural History 1991 ISSN 0003-0082 / Price $1.60 2 AMERICAN MUSEUM NOVITATES NO. 3027 cifico al oeste extremo de Panam'a. Una lagartija algo fuera del intervalo de variacion de casi 300 juvenil y muy pequeiia de las tierras bajas del Ca- especimenes examinados de Costa Rica y Panama ribe se presenta tambien aqui, aunque su asigna- occidental. cion a la especie cherriei es provisional porque cae INTRODUCTION The Middle American herpetofauna in- southwestern headwaters of the Rio Guabo, cludes three seemingly related small skinks 780 m elev. (8°47'N, 8211 'W), Province of (assatus, cherriei, incertus) that until recently Bocas del Toro, western Panama. were referred to the genera Lygosoma (e.g., ETYMOLOGY: The species name is a Latin Stuart, 1940), Scincella (e.g., Smith and Tay- adjective alluding to the rarity of this new lor, 1950), or Leiolopisma (e.g., Taylor, 1956; lizard, known from a single specimen. Stuart, 1963; Peters and Donoso-Barros, DIAGNosIs: A short-limbed New World 1970). Sphenomorphus (sensu Greer, 1979) lacking Greer (1974: 32-34) removed these genera supranasals and prefrontals, with single large from consideration and boldly transferred as- frontoparietal, single loreal, median pair of satus, cherriei, and incertus into Sphenomor- nuchal scales not enlarged, median pair of phus-a genus otherwise occurring "from preanal scales enlarged, low number (;26) southern and eastern Asia through the Indo- of rows of smooth scales at midbody, with a Australian Archipelago to the Solomon Is- median window (palpebral disk) in lower eye- lands and Australia" (Greer, 1979: 323). Vil- lid, and with phalangeal formulae of 2-3-4- la et al. (1988) used this generic arrangement 4-3/2-3-4-5-3. The several New World spe- but did not cite Greer in their "Bibliographic cies of Scincella (sensu Greer, 1974: 32), Checklist"-an omission which apparently which occur in Mexico and the United States, caused them to add a fourth New World spe- are most easily separated from New World cies, "Sphenomorphus" gemmingeri (Cope), Sphenomorphus by the presence of paired an unintentional new combination for a Mex- frontoparietals. ican species that Greer (1974: 32) had placed Sphenomorphus rarus appears to be readily in Scincella. distinguished from all its New World con- In any case, zoogeographic conclusions geners (as well as from New World Scincella, must not yet be drawn from the New World see above) in lacking prefrontal plates, and distribution because Sphenomorphus is a ple- in having the frontonasal plate markedly con- siomorphic taxon not at present definable by cave posteriorly and in broad contact (owing derived characters. It is a taxonomically "re- to absence ofprefrontals) with the frontal (fig. sidual group" (Greer, 1979: 322) ofover 120 2). species; it serves as a convenient repository Sphenomorphus rarus is additionally dis- for the New World (and other) species pend- tinguishable from Costa Rican and Pana- ing further phylogenetic analysis. manian populations of its geographically The purposes of the present paper are to closest relative, S. cherriei, in having (1) few- describe a fourth species of Sphenomorphus er subdigital lamellae on the fourth toe (11 (fig. 1), from the southern end of the New in rarus vs. 13-18 in cherriei), (2) fewer mid- World range, and to document the occur- body scale rows (26 in rarus vs. 29-32 in rence of S. cherriei in Panama. cherriei), and (3) shorter limbs (digits of ad- pressed limbs widely separated by z 10 scales Sphenomorphus rarus, new species in adult d rarus, digits usually approaching to within a few scales or actually touching or Figures 1-3, 4A greatly overlapping in cherriei). The type HOLOTYPE: AMNH 129836 (field no. CWM specimen ofrarus further differs from the great 17250), an adult male caught by C. W. Myers majority of cherriei specimens in having a in company with J. W. Daly on January 13, single median window in the lower eyelid, 1983, in lower montane rain forest on the and in having one rather than two loreals. 1991 MYERS AND DONNELLY: SPHENOMORPHUS 3 N% Fig. 1. Sphenomorphus rarus, new species. The holotype (AMNH 129836) in life, approximately x 2. There also are differences in phalangeal for- pair ofslightly enlarged dorsolateral nuchals, mulae and hemipenes -see Comparisons for separated by two small undifferentiated nu- further discussion and for practical differ- chals situated posterior to interparietal su- entiation from other Panamanian skinks or ture. Minute tubercles (presumed sensory or- skinklike lizards. gans) present on anterior head plates, being most numerous on rostral, frontonasal, and HOLOTYPE supralabials. DESCRInrION OF Nasal rhomboidal, longer than high, with The undissected holotype is a male, ap- naris centrally situated; nasals widely sepa- parently adult, with everted hemipenes. rated by frontonasal. Loreal one. Preoculars Length from tip of snout to vent (SVL) 52 two. Superciliaries eight; first superciliary mm; snout to eye 3.2 mm; snout to ear 9.0 largest, in contact above with posterolateral mm; snout to base of forearm 17 mm; trunk edge frontonasal and (narrowly) with antero- length from axilla to groin 27 mm; greatest lateral edge frontal, in contact below with up- head width (between angles ofjaws) 7.2 mm; per preocular and (narrowly) with loreal. Cil- greatest body width 9.0 mm. Tail partly re- iaries 10/8; a small scale interposed above generated, 49 mm in length (total length 101 + anterior ciliary and below suture between first mm). Limbs pentadactyl (5th toe ofleft fore- two superciliaries. Scales (lower ciliaries) limb missing due to injury) and short, well along edge of lower eyelid 15/12, the first separated by space of 10 scales when ad- lying posterior to suture between preoculars. pressed against body; straightened limbs Lower eyelid movable, scaly, with elongated measuring (from insertion to tip of longest median window (fig. 2). Subocular row in- digit) about 9 mm forelimb (17.3% SVL), 15 complete, separated by fourth supralabial be- mm hind limb (28.8% SVL). low center of eye, with three presuboculars Snout rounded in dorsal and lateral aspect. and two postsuboculars. Several small pre- Rostral twice as wide as high, in broad con- temporals. Primary temporal one, separated tact with frontonasal posteriorly. Frontonasal from parietal by a pretemporal. Secondary wider than long, with posterior margin temporals two, the lower larger than primary broadly and conspicuously concave. Prefron- temporal. Six supralabials on each side. tals absent. Frontal longer than wide. Fron- Six infralabials on each side; mental more toparietal single, the largest plate on head. than twice as wide as long; postmental longer Four large supraoculars on each side. Inter- than mental, in contact with first two infra- parietal relatively small, triangular; pineal eye labials on each side; three pairs of enlarged poorly defined, situated in posterior half of chin scales, with first pair in broad contact, interparietal. Parietals much wider than long, second pair separated by one scale row, third in contact behind interparietal, laterally in pair separated by three scale rows. contact with upper secondary temporal. A External ear opening a large vertically 4 AMERICAN MUSEUM NOVITATES NO. 3027 3 mm. Fig. 2. Head of Sphenomorphus rarus, new species (AMNH 129836, holotype). Translucent (i.e., nonpigmented) scales of the lower eyelid are shaded gray. aligned oval (smaller than eye opening), with- Forefoot, I 3/4 II 5/6 III 7/7 IV 7/7 V ?/4. out lobules or spines. Scales smooth and un- Hind foot, I 3/3 II 8/7 III 9/11 IV 11/11 striated, in 26 rows around midbody; 29 rows V 6/5. around neck just anterior to forearm; about Median pair ofenlarged preanal scales (about 19 rows around base of tail.