






































Iguana b&w text


IGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 157DOMINICAN RACERS

Agriculture & the Environment, Commonwealth of Dominica,
was instrumental in issuing permits to conduct research in
Dominica and facilitated our efforts in myriad ways. Fieldwork
was funded by a grant from the National Science Foundation
(USA) to Robert Powell (DBI-0242589).

Literature Cited
Henderson, R.W. and R. Powell. 2009. Natural History of West Indian

Amphibians 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.), Ecological
Consequences of Artificial Night Lighting. Island Press, Washington, D.C.

Perry, G. and J. Lazell. 2000. Liophis portoricensis anegadae (NCN). Night-light
hunting. Herpetological Review 31:247.

Alsophis antillensis sibonius is endemic to Dominica, Lesser
Antilles. Although Schwartz and Henderson (1991)

described adults, thorough descriptions of juveniles have not
been published. During a June 2008 study conducted primarily
at Cabrits National Park, we made >160 observations of an
undetermined number of snakes. Included in the observations
were five juveniles, for four of which we collected and recorded
pattern data. The only previous description of the juvenile pat-
tern was by Parker (1933): “… an undulating dark vertebral
stripe, a narrow lateral line, and dark spots on the flanks and
hinder parts of the belly.”

The top of the head in juveniles is uniformly brown, dark-
ening laterally, with very dark brown to black lines extending

from the snout and through the eyes before blending into the
darker elements of the body pattern. Supralabials are white,
sometimes with faint specks of light brown or gray. Faint to
moderately distinct stippling occurs on infralabials, chin, and
throat.

Juveniles have distinct brown middorsal “saddles” faintly
outlined in black on a white to pale gray or tan ground color.
Most saddles on any one individual are in contact, forming a
continuous middorsal line with paired lateral extensions. These
saddles may be obliquely situated or offset, forming a wavy
(“zigzag”) line along at least portions of the dorsum. At least a
few saddles on each animal are isolated by pale ground color
extending across the middorsal line. On all juveniles examined,

Juvenile Pattern and Ontogenetic Pattern
Changes in Dominican Racers

Lauren A. White1 and Peter J. Muelleman2

1Environmental 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 position
at the base of a light such as that illustrated on the facing page. This
foraging posture, with the anterior portion of the body elevated at the
base of the light, is essentially similar to that observed in snakes at the
bases of tree trunks in more “natural” habitats (L.A. White and P.J.
Muelleman, pers. comm.).R

O
B

ER
T 

PO
W

EL
L

Iguana 15.3 b&w text  9/10/08  5:43 AM  Page 157



the dorsal saddles are most distinct anteriorly, where they alter-
nate laterally with patches of light ground color. Saddles become
progressively less sharply outlined posteriorly and onto the tail,
where the lateral patches of light ground color fuse to form
vague lateral stripes that disappear completely on the tail. Faint
ventrolateral brown or gray blotches alternate with the dorsal
saddles anteriorly and fade into vague stippling posteriorly. The
venter 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 expand
and fuse (= abundism), to the extent that the light ground color
is increasingly obscured, in many instances leaving as remnants
only light lateral patches. The smallest juvenile examined (186
mm SVL) had 65 pairs of distinct dorsolateral light patches
between saddles. These were more obvious, even posteriorly on
the body and on the tail, than in larger snakes. Two juveniles of
intermediate 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 MUELLEMAN

Juvenile Dominican Racers (Alsophis antillensis sibonius) (186 mm SVL, ~230 mm SVL, and 290 mm SVL, respectively) with the distinct pattern
characteristic of small snakes.

R
O

B
ER

T 
PO

W
EL

L

Iguana 15.3 b&w text  9/10/08  5:44 AM  Page 158



Lesser 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 entirely
terrestrial 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. 

JE
FF

R
EY

 W
. A

C
K

LE
Y

Martinique 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. 

R
O

B
ER

T 
PO

W
EL

L



Male Lesser Antillean Iguanas (Iguana delicatissima) avidly defend territories. On the grounds of the
Sunset 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 IGUANA
14(4), p. 222). See article on p. 130 and travelogue on p. 162. 

JE
FF

R
EY

 W
. A

C
K

LE
Y



Proud sponsor of the IRCF and this centerfold



The 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 by
digging. 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. 

O
LI

V
IE

R
 B

O
R

N

In sharp contrast to the successful reproduction in the Katerniaghat Wildlife Sanctuary, more than 100 Gharials (Gavialis gangeticus) died in the Chambal
River Wildlife Sanctuary this year. An unidentified toxin is suspected of causing kidney damage and failure. See article on p. 150. 

SU
R

ES
H

 C
H

A
U

D
H

A
R

I



IGUANA  •  VOLUME 15, NUMBER 3  •  SEPTEMBER 2008 159DOMINICAN RACERS

tern was recorded in photographs) had 33 and 52 distinct dor-
solateral light patches, with darker pattern elements blending
posteriorly. The largest of the three juveniles (290 mm SVL) had
50 distinct pale dorsolateral light patches and the darker dorsal
saddles were discontinuous near midbody, where 3–4 pale
blotches extended middorsally through the saddle pattern.
Posteriorly, the darker elements condensed into a middorsal
stripe, and virtually all indications of the anterior pattern of sad-
dles and patches were lost.

When juveniles are compared with larger adults and
subadults, the head pattern may be retained essentially
unchanged in some individuals or the tops of heads may become
increasingly dark to the extent that the distinct juvenile ocular
lines are subsumed into the uniformly dark dorsal and lateral
head coloration. The light labial line is variously invaded by
darker pigment. In larger snakes that retain some vague sem-
blance of the juvenile pattern, the line may extend posteriorly
onto 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 with
a series of variously defined white, cream, or yellowish lateral
patches that vary in number and in how far posteriorly they
extend onto the body. Parker (1933) described the adult pattern
as “… posterior part of the body is almost entirely black, but
anteriorly the dorsal stripe is broken up into a series of large oval
spots narrowly separated from one another; the light interspaces

may be fused on the sides of the neck to form a fairly distinct
light stripe.” Schwartz and Henderson (1991) described it as
“anteriorly large white to tan blotches on brown to black
ground, sometimes alternating to form lateral zigzag, posterior
solid black.” We observed adult “ground colors” ranging from
dark taupe through milk chocolate to very dark brown, dark
slate gray, and jet black. “Blotches” of adults ranged from a few
lateral light spots restricted to the anteriormost portion of the
body to series of patches extending to midbody and, in a few
individuals, the full extent of the body. The chin, throat, and
anterior portion of the venter remain light, but variously stip-
pled. Stippling becomes increasingly prominent posteriorly. The
posterior ventrals and subcaudals are uniformly dark brown or
slate gray. The transition from stippling to uniform dark color
may occur as early as one-fourth the length of the body to well
beyond midbody. The apparently ontogenetic changes in pat-
tern are suggestive of progressive but variable abundism (=
pseudomelanism).

Acknowledgements
We thank our mentors, Bob Henderson (Milwaukee Public
Museum) and Robert Powell (Avila University), for guidance
and support. They and John S. Parmerlee, Jr. made invaluable
comments on earlier drafts of this manuscript. We thank Adam
Mitchell, Ruthie Carter, and Seth Rudman for their help in the
field. Mr. Arlington James, Forest Officer, Forestry, Wildlife, and
Parks Division, Ministry of Agriculture & the Environment,
Commonwealth of Dominica, was instrumental in issuing per-
mits to conduct research in Dominica and facilitated our efforts
in myriad ways. Fieldwork was funded by a grant from the
National Science Foundation (USA) to Robert Powell (DBI-
0242589).

Literature Cited
Parker, 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 West
Indies: Descriptions, Distributions, and Natural History. University of
Florida 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. 

JO
H

N
 S

. P
A

R
M

ER
LE

E,
 J

R
.

An adult Dominican Racer showing the white labial line extending
onto the body. 

R
O

B
ER

T 
PO

W
EL

L

Iguana 15.3 b&w text  9/10/08  5:44 AM  Page 159




