I

Asiatic Herpetological Research

April 1990

Intergradation Between Melanochelys trijuga trijuga and M.
(Testudines: Emydidae: Batagurinae)

Vol. 3, pp. 52-53t.

coronata

INDRANEIL DAS AND PETER C. H. PRITCHARD 2
11Animal Ecology Research Group, Department of Zoology, Oxford University, Oxford 0X1 3PS, England^Florida Audubon Society, 1101 Audubon Way, Maitland, Florida 32751, USA

Key words: Reptilia, Testudines, Emydidae, Melanochelys, India, distribution, intergrade.

The Indian Black Turtle or pe amai,Melanochelys trijuga,abundant chelonians

isone of the mostin the Indian

subcontinent, with a distribution extending
from Sri Lanka (Deraniyagala 1939),

through India and Burma, to western
Thailand (Wirot 1979), although apparentlyexcluding

Bangladesh(Das,1989).

Nevertheless, details of the distribution of
the seven described subspecies remain
obscure. The range maps provided bySmith (1931), Das (1985), and Tikader andSharma (1985) indicate rather clearly
allopatric distributions for the Indian
subspecies, but the overall range of thespecies is based on extremely few andwidely-separated locality points (except for
Sri Lanka and Kerala), as is evident in theprovided by Iverson (1986).
Deraniyagala (1939) recognized twomap

subspecies in Sri Lanka, but the geographic
separation, if any, between these two forms
was not made clear.

Of the various subspecies, the mostdistinctive is probably Melanochelys trijuga

coronata, whose distribution is restricted tothe state of Kerala in southwestern India(the distribution map provided by Tikaderand Sharma (1985) involves a transpositionof the range of coronata and trijuga ). M.
t. coronata
has a striking head pattern, witha broad, black diamond-shaped marking on

the crown of the head, contrasting with thewhite to yellow temporal region. The headpattern of the other subspecies consists at
most of small, yellow to pink spots andreticulations that may disappear with age.
The shell as a whole is usually unrelieved
black, in contrast to other subspecies inwhich at least a lighter plastral rim isevident (although Deraniyagala (1939)

1990 bv Asiatic ileroetoloeical Research

reported completely black specimens of M.
ttrijuga from Kalpitiya, Sri Lanka andwe have seen increased pigmentation withage in the north Indian subspecies,indopeninsularis, in which adult animals
may lose the lighter plastral rim). The
distribution of M. t. coronata is generallyindicated as widely separated from that ofM. t. trijuga by the Western Ghats, but thesouthward penetration of the forma typica
into the hiatus between these twosubspecies is not represented on existing
range maps, and the subspecificrelationship between these two forms hasbeen assumed rather than demonstrated.
here report upon four specimens that.

We

bridge the geographic map between M. t.
trijuga and M. t. coronata, and three thatshow characters intergradient betweenthem.

Anadultmale (CL 23.9 cm;CW

16.4 cm) was collected by the two authors
from a dry stream bed in Chichli, IndiraGhandi (formerly Annamalai) Wildlife
Sanctuary, Coimbatore District, Tamil
Nadu, on March 27, 1989 (Fig. 1). The
right anterior margin of the shell showedof an old injury, with several
peripheral bones lost. The head pattern ofthe specimen included the diamond- shaped
marking typical of Melanochelys trijuga
coronata. The yellow head reticulations
and the yellow plastral margin is suggestiveof M. t. trijuga, and the size of thespecimen is greater than that of any
recorded specimen of M. t. coronata(maximum 17.5 cm (Smith 1931) or
18 cm (Tikader and Sharma 1985) ofsigns

20.8 cm (Das 1985)). The specimen was
retained alive and housed at the Madras
Crocodile Bank.

Asiatic Herpetological Research

April 1990

Vol. 3, p. 53

different subspecies east and west of theGhats, but the ability of M. trijuga to exist
far from water suggests that individuals

wandering into these hills may provide thestock for an intergradient population. It
to search for alowland intergradient population in thecoastal area at the northern extreme of thedistribution of M. t. coronata.

would be worthwhile

OtherFIG. 1. Intergrade between Melanochelys trijuga
coronata and M. t. trijuga.

A second specimen — a fragmentaryshell only

— wasalso found in the Indira

Ghandi Wildlife Sanctuary, in a tribalsettlement. The nuchal area and anterior
peripherals are missing. Shell width is13.7 cm, again indicating a specimen larger
than is typical of Melanochelys trijuga
coronata. Ankylosis of the shell, asillustrated for Sri Lanka specimens byDeraniyagala(1939),

iscases

peripheral

congeneric

tempted to interpret the different markings
as a means of avoiding cross-matings insituations of sympatry. But, the overall
allopatry of the species of Rhinoclemmys
in northern South America, for example,
suggests that this interpretation may be anincomplete one, as does the discovery ofintergradation between adjacent populationsof Melanochelys

that differ primarily incephalic pigmentation.

essentially

Literature Cited

complete, except for faint indications of thesutures.

ofexistbatagurine species of a similar ecologicalrole differing primarily in head pattern, as
is the case with some of the species ofRhinoclemmys in the Neotropics. One isThe specimen

isregistered as PCHP 2803 in the private
collection of the second author.

DAS, I.

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two intergradientwereinfound
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Zoological Survey of India (Madras), bothcollected by M. Vasant and party. An8.1

cm juvenile (Lot no. 10) was collectedat Kombiar Charagam, Kalakkadu Wildlife

Sanctuary, Turunelveli District, Tamil
Nadu (altitude 210 m), on October 13,
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Melanochelys trijuga is basically a pond
and the Western Ghats appear toseparate the essentially lowland ranges ofM. t. coronata and M. t.
trijugaturtle,Nevertheless, the new localities all fallwithin upland areas actually in the WesternGhats. It appears that the hills may form asufficient barrier to allow the evolution ofReptilia andLoricata, Testudines.
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