Asiatic Herpetological Research

1997

Vol. 7. pp. 19-22

A New Gecko of the Genus Gonydactylus (Sauria: Gekkonidae) with a Key tothe Species from Vietnam
ILYA S. DAREVSKY

1

AND NIKOLAI N. SZCZERBAK 2

Zoological Institute, Russian Academy of Sciences, St. Petersburg 199034. Russia; 'Institute of Zoology
Ukranian Academy of Sciences, Kiev 252650, Ukraine

Abstract: Gonydactylus paradoxus sp. nov from a small off-shore island in South Vietnam distinctly differs fromall

other known species of the genus Gonydactylus in the absence of preanal and femoral pores in males andfemales.

The occurrence in a new insular species of a feature so unusual for the genus Gonydactylus may be an

external manifestation of founder effect sensu E. Mayr(1942).

Key words: Lizards. Gekkonidae. Gonydactylus, femoral poresbaFigureLower surface of the right manus (a) and2.

right pes (b) of a holotype of Gonydactylus paradoxus

sp. nov.

Among the most important diagnostic charactersin the genus are the pattern of disposition and number

Figure 1 Lateral view of head (a) and preanal andfemoral areas (b) of a holotype of Gonydactylus para.

of femoral and preanal pores, which are present inspecimens of all known species of Gonydactylus.
Some years ago on a small offshore island of South

Vietnam thefirstauthor collected a series of speci-

doxus sp. nov. Note the rows of enlarged preanal andmens of a species of Gonydactylus

femoral scales.

both femoral and preanal pores.
A more detailed
examination has shown that these lizards constitute aIntroduction

devoid ofof the genus Gonydactylus.
ofthisform
is provided below.
descriptionrare

The validity of the genus Gonydactylus Kuhl et van

newtotallyspecies

AThe following acronyms and abbreviations are
ZIL - Zoological Institute. Russian Academy ofHasselt. 1822. originally described at the beginning of
the last century and long regarded as a synonym of theused:genus Cyrtodactylus Gray. 1827, has recently been
advocated by Kluge (1991). According to the latter

Sciences. St. Petersburg;

author and current literature Gonydactylus comprises

vent length; TL - tail length.

62 species widely distributed within the South andSouth-Eastern Asia. Some of them have been only

Gonydactylus paradoxus sp. nov. (Figures 1-

recently described from theBorneo (Hikida. 1990)

and from Thailand (Ulber. 1993).

ZMK-Zoological Museum.

Ukranian Academy of Sciences, Kiev; SVL - snout-3)

ZIL 203 K), Hon Thorn Isle near south
Phu Quoc Island. Kieng Giang Province.

Holotype:
point of1997

Asiatic Herpetological ResearchVol. 7. p. 20

Figure 3. Dorsal coloration variability in six paratype specimens of Gonydactylus paradoxus sp. nov.

South Vietnam, coll. I. Darevsky, April 13, 1987. adultmale.

Z1L 20311-20315. 204-21. 20422,
Paratypes:20479-20481: ZMK Re 22. 23a (7 males. 6 females).

approximately 44 granules between palpebral
borders of eyelids at the middle of the orbits; granules

area;

on the back of the head intermixed with few small
conical scales;

10/9 supralabials; mental triangularwith labial border wider than labial border of rostral;

Same data as for holotype.
The species name derives from theEtymology:
Greek word "paradoxes" - unusual, strange: in thepresent case referring to the lack of femoral and preanal pores.

9/9 lower labials; one large pair of postmental about
1/2 the size of thefirst; four gular scales bordering
postmentals between second postmentals followed by small gular granules. Dorsal surface of thefirstand femoral pores in males orbody with fine scales mixed with about 16 irregularrows of small rounded conical or trihedral tubercles;
small tubercles developed on dorsal part of legs; ventrolateral folds feebly indicated by low rounded tuber-females; enlarged femoral scales distinct: 26-36 mid-cles; ventral scales small, cycloid, equal in size; aboutventral scale rows between indistinct lateral folds; 17-30 scalerows between ventrolateral folds; approximately 135 scales in a row from chin shields to vent at

Diagnosis: A medium-sized species of Gonydactylus
with an adult body size of 45-84
nal groove, no preanalmm in SVL: no prea-

23 subdigital lamellae under fourth toe; a medianseries of transversely widened subcaudal scales; irregular crossbands on the dorsum.

medial ventral line; one row of enlarged smooth femoral scales on underside of thighs; no femoral and pre-mmDescription of the holotype: Adult male. 80
TL; head oviform; forehead concave;
SVL; 95mm

anal pores;

tailroundincross-section,verticilate,snout obtusely pointed; ear opening oval; eye withcovered dorsally and laterally with small granules,
with 4-6 low tubercles near posterior part of each seg-vertical Gekko-type pupil; rostral large, quadrangular,ment; a median series of transversely widened sub-partially split

by a median vertical cleft, contacting

nostrils, first upper labials and three enlarged internasals; first upper labial, two postnasals, supranasal

androstral forming border of nostril; scales on snout threeor more times larger than on occiput or interorbital

caudals.

Color (in life): Head and body yellow-brown above,
lighter below; back with seven brown-bordered light
undulating transverse bands, divided by a narrow Ion-

Asiatic Herpetological Research

1997

Vol. 7, p. 21

the presence of bright white transverse ringson thewhich are hardly noticed in the adults.

tail,Comparative notes: The intrageneric systematics ofthe genus Gonydactylus has been largely based on thepattern of scuttelation of theareas.

preanal and femoral

The presence of more or less well developed

preanal or femoral pores is characteristic of all of previously-described representatives of the genus, thenumber and disposition of these pores significantly
varying in different species. The pores are commonly
present in males only, although these may occasionally be distinguishable in females too. Some species
display both femoral and preanal pores, whereas others possess either the former or the latter.

There are 15 species of Gonydactylus in Indochof which are known from Vietnam.

ina, four

All ofthem, with the exception of G. paradoxus exhibits thepresence of preanal pores. As mentioned above, thisnew species has no pores at all. and thus differs fromother representatives of the genus.

In this regardG.

some Thai

paradoxus exhibits some similarity
specimens of G. oldhami whose males have generally
to

1-4 preanal pores, but which may lack pores entirely(Smith. 1935; Taylor, 1963; Ulber, 1993).

However,

G. oldhami definitely differs from G. paradoxus in a

number of other characters, particularly in possessing
Figure 4. Type locality (Indicated by arrow) of Gonydactylus paradoxus sp. nov. at Thorn Island, Kien

a non-segmented tail and characteristic white spots on
the back.

Among other Indochinese species, the newspecies, according toGiang Province. South Vietnam.

itscoloration andsome othermarkers, seems to be somewhat close to G. annularis

Smith from south Thailand, but differs from it in some
gitudinal vertebral stripe;

tailwith dark rings sepa-

rated by narrow light interspaces.

ventral scale rows between a ventrolateral folds (ver-The paratype specimens resemble

Variation:

theSVL of sevenmajor characters.
mature males 41.0-84.0 mm and 50.3-78.0
forholotype

incharacters, in particular in a larger number (40-48) ofallmmsus 30-34 in G. paradoxus).

On the basis of themajority of its characters the newly described species

obviously also differs from G. condorensis (Smith,rows between ventrolateral1921). a Vietnamese endemic insular species fromfolds 30-34; scales in a row from chin shields to ventPulo Condore (Con Dao) Island in the South China

maturefemales;scale

188-144. Variations in dorsal coloration are shown in

Sea. Literature records (Bobrov. 1995) citing G. phil-Fig. 3.

ippinicus from Vietnam are not confirmed by voucher

Distribution: All specimens are known only from thematerial and seem to be erroneous.

type locality on(Fig. 4).

ItHon Tom Island in South Vietnam

can be assumed that this island species

also occurs one some of the neighboring small islandsin the Gulf of Siam.

Field notes: All specimens from the type series werecollected at night on dry rocks under the canopy of asecondary dipterocarp

forest.

By day, however, nogeckos were detected at the same place.

Reproduction:

Four females kept in terraria laid 2eggs repeatedly. Following about 55 days of incubain total length weretion, young geckos 45-47mm

hatched.

A peculiar coloration of the young involves

lar

As is generally known, insular animals, in particusome reptile species, often display unusual mor-

phological characters (Mertens, 1934), which may beregarded as a manifestation of the so called "foundereffect",originallyformulated by E.

Mayr(1942).

This principle attributes genetic uniformity and phenotypic specificy of specimens within an isolated population to an origin from a small founding population,

perhaps a single fertilized female, which might possess certain features not characteristic of the species.
It isassumed that the insular population of Gonydac-

tylus on Hon Thorn may have originated from an acci-

Asiatic Herpetological ResearchVol. 7, p. 22

dentally

femaleintroduced

controlling the formation insome genes
femoral orofontogeny
having1997

Darevsky, I. S. 1990. Notes on the reptiles (Squamata) of some offshore island along the coast of Viet-nam. Pp. 125-129

preanal pores (Darevsky et al., 1991 ).

In:

Peters G. and R. Hutterer (eds.).

Vertebrates in the Tropics. Proc. Int. Symp. Biogeog-

Key to the species of Gonydactylus in Viet-nam
1(6)raphy and Systematics in the Tropics. Bonn.

V

Underside oftailwith transversely enlarged

Darevsky, I. S., A. G. Ponomarenko. and G.
Kuznetzov.
99[Zoogeography of offshore island
1plates.

of Vietnam].

2(3) Body handed with four distinct dark light-edgedsian).

G. intermedins Smith.

dorsal cross-bars

3 (2) Body without distinct banded pattern.

4 (5) Males with a group of 4 to 7 preanal pores; 35-40 scales across the belly

G. condorensis Smith.

5 (4) Males and females without preanal pores: 30-34

G. paradoxus sp. nov.

scales across the belly

1.

Priroda,Moscow, 9:42-48.

(InRus-Hikida. T 1990. Bornean Gekkonid Lizards of theGenus Cyrtodactylus (Lacertilia: Gekkonidae) with

Description of Three New Species. Japanese Journalof Herpetology 13:91-107.

Kluge, A. G. 1991. Checklist of Gekkonid Lizards.
Smithsonian Herpetological Information Service. No.
85:1-35.

6(1) Underside of tail with numerous roundish scales
G. irregularis Smith.

Martens. R.

Acknowledgments
within1934.

Die Insel-Reptilien. ihre Ausbere-itung. Variation and Artbildung.

We are grateful to the participants of the Soviet-Vietnamese expedition

Mayr. E. 1942. Systematics and the origin of species.

Columbia University Press, N.Y.

ProjectNo.

7oftheUNESCO ("Ecology and rational exploration of islandecosystems") for help during field work on Vietnamese offshore islands.

Smith.

M .A.

1935.

Zoologica 32: -209.
1

The Fauna of British India,including Ceylon and Burma. Reptilia and Amphibia.
Vol. II. Sauria: 1-440.
Taylor. E. H.

1963.

The Lizards of Thailand. Univer-sity of Kansas Science Bulletin XLIV: 1-1077.

Literature CitedBobrov,V V.

1995.

Checklist and bibliography ofthe lizards of Vietnam.

Smithsonian HerpetologicalInformation Service. No. 105:1-28.

1993.
Ulber. T.
Bemerkungen uber cyrtodactyline
Geckos aus Thailand nebst eshreibungen von zwei
neuen Arten (Reptilia: Gekkonidae). Mitt. Zool. Mus.
Berl. 69:187-200.