Muelleman, Peter J.

White, Lauren A.

English

The University of Kansas: Journals@KU

IGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 157DOMINICAN RACERSAgriculture & the Environment, Commonwealth of Dominica,was instrumental in issuing permits to conduct research inDominica and facilitated our efforts in myriad ways. Fieldworkwas funded by a grant from the National Science Foundation(USA) to Robert Powell (DBI-0242589).Literature CitedHenderson, R.W. and R. Powell. 2009. Natural History of West IndianAmphibians and Reptiles. University Press of Florida, Gainesville.Perry, G. and R.N. Fisher. 2006. Night lights and reptiles: Observed and poten-tial effects, pp. 169–191. In: C. Rich and T. Longcore (eds.), EcologicalConsequences of Artificial Night Lighting. Island Press, Washington, D.C.Perry, G. and J. Lazell. 2000. Liophis portoricensis anegadae (NCN). Night-lighthunting. Herpetological Review 31:247.Alsophis antillensis sibonius is endemic to Dominica, LesserAntilles. Although Schwartz and Henderson (1991)described adults, thorough descriptions of juveniles have notbeen published. During a June 2008 study conducted primarilyat Cabrits National Park, we made >160 observations of anundetermined number of snakes. Included in the observationswere five juveniles, for four of which we collected and recordedpattern data. The only previous description of the juvenile pat-tern was by Parker (1933): “… an undulating dark vertebralstripe, a narrow lateral line, and dark spots on the flanks andhinder parts of the belly.”The top of the head in juveniles is uniformly brown, dark-ening laterally, with very dark brown to black lines extendingfrom the snout and through the eyes before blending into thedarker elements of the body pattern. Supralabials are white,sometimes with faint specks of light brown or gray. Faint tomoderately distinct stippling occurs on infralabials, chin, andthroat.Juveniles have distinct brown middorsal “saddles” faintlyoutlined in black on a white to pale gray or tan ground color.Most saddles on any one individual are in contact, forming acontinuous middorsal line with paired lateral extensions. Thesesaddles may be obliquely situated or offset, forming a wavy(“zigzag”) line along at least portions of the dorsum. At least afew saddles on each animal are isolated by pale ground colorextending across the middorsal line. On all juveniles examined,Juvenile Pattern and Ontogenetic PatternChanges in Dominican RacersLauren A. White1 and Peter J. Muelleman21Environmental Science Program, Oklahoma State University, Stillwater, Oklahoma 74078, USA (lauren.a.white@okstate.edu)2Department of Biology, Truman State University, Kirksville, Missouri 63501, USA (pjm563@truman.edu)A Dominican Racer (Alsophis antillensis sibonius) in a foraging positionat the base of a light such as that illustrated on the facing page. Thisforaging posture, with the anterior portion of the body elevated at thebase of the light, is essentially similar to that observed in snakes at thebases of tree trunks in more “natural” habitats (L.A. White and P.J.Muelleman, pers. comm.).ROBERT POWELLIguana 15.3 b&w text  9/10/08  5:43 AM  Page 157the dorsal saddles are most distinct anteriorly, where they alter-nate laterally with patches of light ground color. Saddles becomeprogressively less sharply outlined posteriorly and onto the tail,where the lateral patches of light ground color fuse to formvague lateral stripes that disappear completely on the tail. Faintventrolateral brown or gray blotches alternate with the dorsalsaddles anteriorly and fade into vague stippling posteriorly. Theventer is white with faint tan to gray stippling increasing in den-sity and becoming darker toward the vent.As snakes grow, the dark elements of the pattern expandand fuse (= abundism), to the extent that the light ground coloris increasingly obscured, in many instances leaving as remnantsonly light lateral patches. The smallest juvenile examined (186mm SVL) had 65 pairs of distinct dorsolateral light patchesbetween saddles. These were more obvious, even posteriorly onthe body and on the tail, than in larger snakes. Two juveniles ofintermediate length (240 mm SVL and a slightly smaller indi-vidual that was released before measurement, although the pat-158 IGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 WHITE AND MUELLEMANJuvenile Dominican Racers (Alsophis antillensis sibonius) (186 mm SVL, ~230 mm SVL, and 290 mm SVL, respectively) with the distinct patterncharacteristic of small snakes.ROBERT POWELLIguana 15.3 b&w text  9/10/08  5:44 AM  Page 158Lesser Antillean Iguana (Iguana delicatissima) are almost exclusively herbivorous (the yellow color on the iguana’s face is from eating mangos) and largely arbo-real, descending to the ground to forage or defend territories for only short periods each day. Dominican Ground Lizards (Ameiva fuscata) are almost entirelyterrestrial and are opportunistic foragers that feed mostly on small invertebrates, but will eat fruits when available. These two individuals came into close prox-imity to bask in a small patch of sunlight. See article on p. 130. JEFFREY W. ACKLEYMartinique Frogs (Eleutherodactylus martinincensis) are ubiquitous on Dominica. This individual has an unusually distinct middorsal “racing” stripe, a pat-tern element sometimes seen in the Dominican Frog (E. amplinympha), which is restricted to higher elevations on the island. See article on p. 130. ROBERT POWELLMale Lesser Antillean Iguanas (Iguana delicatissima) avidly defend territories. On the grounds of theSunset Bay Club on Dominica’s leeward (western) coast, the population density is very high, result-ing in frequent contact between males with neighboring territories. The beads are permanent mark-ers allowing for individual recognition in a long-term study of Dominican iguanas (see IGUANA14(4), p. 222). See article on p. 130 and travelogue on p. 162. JEFFREY W. ACKLEYProud sponsor of the IRCF and this centerfoldThe Katerniaghat Wildlife Sanctuary is a secure refuge and the best hope for protecting Gharials (Gavialis gangeticus) from extinction. In April of this year,26 females laid eggs in a soft and secure sand bar on an island in the Girwa River where nesting had been facilitated by clearing grasses and softening sand bydigging. About 1000 Gharials hatched this year at one location along the river, but many were swept away by monsoon floods, for which protective meas-ures will have to be developed in the future. See article on p. 150. OLIVIER BORNIn sharp contrast to the successful reproduction in the Katerniaghat Wildlife Sanctuary, more than 100 Gharials (Gavialis gangeticus) died in the ChambalRiver Wildlife Sanctuary this year. An unidentified toxin is suspected of causing kidney damage and failure. See article on p. 150. SURESH CHAUDHARIIGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 159DOMINICAN RACERStern was recorded in photographs) had 33 and 52 distinct dor-solateral light patches, with darker pattern elements blendingposteriorly. The largest of the three juveniles (290 mm SVL) had50 distinct pale dorsolateral light patches and the darker dorsalsaddles were discontinuous near midbody, where 3–4 paleblotches extended middorsally through the saddle pattern.Posteriorly, the darker elements condensed into a middorsalstripe, and virtually all indications of the anterior pattern of sad-dles and patches were lost.When juveniles are compared with larger adults andsubadults, the head pattern may be retained essentiallyunchanged in some individuals or the tops of heads may becomeincreasingly dark to the extent that the distinct juvenile ocularlines are subsumed into the uniformly dark dorsal and lateralhead coloration. The light labial line is variously invaded bydarker pigment. In larger snakes that retain some vague sem-blance of the juvenile pattern, the line may extend posteriorlyonto the body. The darker elements of the body pattern expand,often become darker, and outlines become increasingly indis-tinct, resulting in what appears to be a dark ground color witha series of variously defined white, cream, or yellowish lateralpatches that vary in number and in how far posteriorly theyextend onto the body. Parker (1933) described the adult patternas “… posterior part of the body is almost entirely black, butanteriorly the dorsal stripe is broken up into a series of large ovalspots narrowly separated from one another; the light interspacesmay be fused on the sides of the neck to form a fairly distinctlight stripe.” Schwartz and Henderson (1991) described it as“anteriorly large white to tan blotches on brown to blackground, sometimes alternating to form lateral zigzag, posteriorsolid black.” We observed adult “ground colors” ranging fromdark taupe through milk chocolate to very dark brown, darkslate gray, and jet black. “Blotches” of adults ranged from a fewlateral light spots restricted to the anteriormost portion of thebody to series of patches extending to midbody and, in a fewindividuals, the full extent of the body. The chin, throat, andanterior portion of the venter remain light, but variously stip-pled. Stippling becomes increasingly prominent posteriorly. Theposterior ventrals and subcaudals are uniformly dark brown orslate gray. The transition from stippling to uniform dark colormay occur as early as one-fourth the length of the body to wellbeyond midbody. The apparently ontogenetic changes in pat-tern are suggestive of progressive but variable abundism (=pseudomelanism).AcknowledgementsWe thank our mentors, Bob Henderson (Milwaukee PublicMuseum) and Robert Powell (Avila University), for guidanceand support. They and John S. Parmerlee, Jr. made invaluablecomments on earlier drafts of this manuscript. We thank AdamMitchell, Ruthie Carter, and Seth Rudman for their help in thefield. Mr. Arlington James, Forest Officer, Forestry, Wildlife, andParks Division, Ministry of Agriculture & the Environment,Commonwealth of Dominica, was instrumental in issuing per-mits to conduct research in Dominica and facilitated our effortsin myriad ways. Fieldwork was funded by a grant from theNational Science Foundation (USA) to Robert Powell (DBI-0242589).Literature CitedParker, H.W. 1933. Some amphibians and reptiles from the Lesser Antilles.Annals and Magazine of Natural History 10:151–158.Schwartz, A. and R.W. Henderson. 1991. Amphibians and Reptiles of the WestIndies: Descriptions, Distributions, and Natural History. University ofFlorida Press, Gainesville.An adult Dominican Racer with an abundistic pattern in which the dark pattern elements have expanded, with only a few light patches remain-ing of the juvenile ground color. JOHN S. PARMERLEE, JR.An adult Dominican Racer showing the white labial line extendingonto the body. ROBERT POWELLIguana 15.3 b&w text  9/10/08  5:44 AM  Page 159

Juvenile Pattern and Ontogenetic Pattern Changes in Dominican Racers

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Juvenile Pattern and Ontogenetic Pattern Changes in Dominican Racers

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