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Asian Journal of Conservation Biology, July 2020. Vol. 9 No. 1, pp. 78-89 AJCB: FP0124
ISSN 2278-7666 ©TCRP Foundation 2020
A review of the Gekkonid genus Cyrtodactylus Gray, 1827 (Sauria:
Gekkonidae) in the Andaman and Nicobar archipelago with the
description of two new species from the Nicobar Islands
S.R. Chandramouli
Department of Ecology and Environmental Sciences,
School of Life Sciences, Pondicherry University, Puducherry - 605014, India
(Received: December 06, 2019 ; Revised: M ay 25 & June 04 , 2020; Accepted: June 17, 2020)
ABSTRACT
A comprehensive review of members of the gekkonid genus Cyrtodactylus Gray, 1827 from the Andaman and
Nicobar Islands was undertaken to assess the true diversity of the genus in this region. Samples collected across
different islands within the archipelago show significant and consistent morphological variation associated with
the region of origin. Detailed redescriptions are presented for the two known species Cyrtodactylus rubidus and
C. adleri. Two new species C. nicobaricus sp. nov. and C. camortensis sp. nov. are described from the northern
and central group of islands of the Nicobar archipelago based on morphological distinction and geographic
separation from the above two named species from this archipelago. Information on geographic distribution,
natural history and conservation status for all of these species are presented.
Key words: cryptic species, geographic distribution, insular endemic, allopatry, Gekkonid
INTRODUCTION
The Gekkonid genus Cyrtodactylus Gray, 1827 repre-
sents the most species rich genus among old world
geckos and is currently known to compris e over 300
species (Uetz and Hosek, 2020). The distribution of this
genus spans from the Indian subcontinent in the west to
Australia in the East, across tropical Asia and Austral-
asia. Recent studies have demonstrated a very high de-
gree of underestimation of species richness within this
genus (E.g. Grismer et al., 2018a; Quah et al., 2019).
Among these, knowledge on Cyrtodactylus species from
the Andaman and Nicobar archipelago, situated in the
Bay of Bengal, south of the Burmese peninsula (the
Ayerwady Delta) and east of the Indian subcontinent has
been relatively poor. In one of the foremost herpetologi-
cal investigations conducted in the Andaman archipel-
ago, Blyth (1861) described a new gekkonid genus Puel-
lula with the species Puellula rubida from “Port Blair”
in his publication titled “Report of the curator”. Stolic-
zka (1870) transferred this species to the genus Cyrto-
dactylus Gray, 1827 where it rightly belongs and is cur-
rently placed. Later, Biswas and Sanyal (1980) and
Biswas (1984) reported the occurrence of Cyrtodactylus
rubidus from Car Nicobar and Great Nicobar Islands in
the Nicobar archipelago. Das (1997) based on examina-
tion of some of the Nicobarese specimens reported by
Biswas and Sanyal (1984) and also on his own collec-
tions from Great Nicobar, described Cyrtodactylus
adleri as a new species. Recent fieldwork in the Anda-
man and Nicobar archipelago revealed the existence of
*Corresponding Author’s E-mail: findthesnakeman@gmail.com 78
some populations of Cyrtodactylus spp. from the Cen-
tral group of the Nicobar Islands and Car Nicobar Island
that do not conform to these nominate taxa. In this arti-
cle, these two populations present outside the morpho-
logical and geographic boundaries of the two nominate
taxa are described as new species. Additionally, data on
aspects pertaining to taxonomy, morphology, natural
history and distribution are provided for the two known
species, C. rubidus and C. adleri.
MATERIALS AND METHODS
Gekkonids of the genus Cyrtodactylus encountered in
the field were gently restrained, measured, scored for
morphological characters, photographed and released at
the site of capture. Three dead specimens of Cyrtodac-
tylus rubidus, four of C. adleri, three specimens of the
Cyrtodactyus sp. from Car Nicobar and two specimens
of the Camorta Island population were collected from in
and around human habitations between May and Nov
2017 and preserved in 70% ethanol, and are deposited
in the collections of the Department of Ocean Studies
and Marine Biology (DOSMB) Pondicherry University,
Brookshabad, Port Blair. Type specimens of the new
species described here have been deposited in the col-
lections of the Zoological Survey of India, Port Blair.
The following measurements in mm were recorded with
vernier calipers and characters of pholidosis and colour-
ation were scored. Snout-vent length (SVL), measured
from the snout tip to the anterior edge of the cloaca; tail
length (TAL), measured from the posterior edge of the
cloaca till the tail tip; trunk length (AG), measured be-
tween the axilla and groin; head length (HL), measured
from the snout tip till the jaw angle; head width (HW),
measured at the broadest point on the head; head depth
(HD), measured from the top of the head to the throat,
ventrally; horizontal eye diameter (ED), eye-nostril dis-
tance (EN), snout length (ES), measured from the ante-
rior eye margin to the snout tip; distance from eye to
tympanum (ETY), measured from posterior eye margin
to anterior edge of the tympanum; tympanum diameter
(TYD), measured at the widest point of the tympanic
opening; upper arm length (UAL), measured from the
axilla till the elbow; lower arm length (LAL), measured
from the elbow to the wris t; palm length (PAL), meas-
ured from the wrist till the tip of finger III; thigh length
(FEL), measured from the point of insertion of the
hindlimb to the trunk till the knee; tibia length (TBL),
measured from the knee to heel; foot length (FOL),
measured from heel to the tip of toe IV; length of fingers
(F1-F5) and toes (T1-T5) measured from the fork till the
tip excluding claw. Supralabials and infalabials were
counted along the upper and lower lips between rostral
and mental till the gape, respectively. Ventrals were
counted along a transverse series across the unders ide at
mid-body; internasals were counted between the nasal
scales; subdigital lamellae were counted on the ventral
surface of digits on fingers and toes. Geo-coordinates of
the localities where the individuals were encountered
were recorded with a Gamin GPS MAP 78s and mapped
with ARC MAP v. 10.
A principal component analys is was performed
based on s ixteen morphometric measurements and five
meristic characters namely, the number of supralabials,
infralabials , number of subdigital lamellae under toe IV,
number of dorsal tubercle series and the number of ven-
trals, between the superficially similar species pair, C.
rubidus of the Andaman Islands and C. nicobaricus sp.
nov. from Car Nicobar. Character comparisons across
species are restricted to those within the Andaman and
Nicobar archipelago. This is justifiable based on the fact
that many of the Cyrtodactylus species have relatively
narrow and finite geographic distribution ranges
(Grismer et al., 2018a; Welton et al., 2010) and it is
highly unlikely that a species from the Andaman and
Nicobar Islands could have a distribution outside the
Islands across oceanic barriers. So far, despite s everal
studies over the past decades, the two species known
from these islands have never been documented else-
where.
SYSTEMATICS
Cyrtodactylus rubidus (Blyth, 1861) (Figures 1&2;
Table 2)
Puellula rubida Blyth, 1861
Gecko tigris Tytler, 1864: 546
Crtodactylus rubidus – Stoliczka, 1870:165
Gymnodactylus rubidus – Boulenger, 1885: 45; Smith,
1935: 54
Syntypes: ZSI 6208-6210 from ‘Andamans’ (fide Das et
al., 1998)
Chandramouli
79 AJCB Vol. 9 No. 1 , pp. 78–89, 2020
Figure 1. Cyrtodactylus rubidus from South Andaman
(above); Middle Andaman (middle) and Long Island
(below).
Figure 2. (A) dorsal and (b) ventral views of head,
(c) dorsal and (d) ventral views of the trunk, (e) ventral
view of the right foot and (f) precloacal region of a
topootype (DOSMB05069) of Cyrtodactylus rubidus
Material examined: DOSMB05069, DOSMB05073 –
Broo kshabad , Port Bla ir, Sou th Andaman ;
DOSMB05047 – Little Andaman.
Differential diagnosis and comparisons: (Table 1)
Cyrtodactylus rubidus is endemic to islands of the Anda-
man archipelago and is characterized by: moderate adult
body size (SVL 48.59–56.75 mm); intensely tuberculate
dorsum (13–15 transvers e rows at midbody); 10–11 su-
pralabials; nine infralabials; two elongate inner pair of
post-mentals in broad contact with each other; two
smaller, separated outer pair of postmentals; pres ence of
a precloacal groove and up to six precloacal pores lo-
cated around the precloacl groove in males; pres ence of
four enlarged internasals; evident ventrolateral dermal
folds; 38–40 transverse rows of juxtapos ed ventrals (vs.
imbricate in C. adleri and C. nicobaricus sp. nov.); two
pairs of rounded post-cloacal spurs in males; 17–19 sub-
digital lamellae under the IV toe, of which the basal six
are expanded; presence of a nuchal loop formed by post
ocular streaks extending and joining at the nape and a
dorsal colour pattern of 8–9 dark transverse bands on a
dark grey to brown background.
Des cription of a topotype (DOSMB05069):
An adult male, measuring 56.07 mm SVL. Head large,
longer than broad (HL:HW 1.53) with a rounded snout
tip when viewed dorsally; eyes large with a vertically
elliptical pupil, (ED:HL 0.25) but shorter than the snout.
Habitus depressed, with a long trunk (AG 23.4). Su-
pralabials 11/11; infralabials 9/9; mental triangular;
bounded by a large pair of rhomboidal inner pair of post-
mentals, in contact with each other; outer pair smaller
and separated. Dorsum covered by nearly uniform,
rounded tubercles (lacking keels ) throughout; in 15
trans verse rows. Ventral scales circular; juxtaposed.
Precloacal groove evident; demarcated by a thin dark
line separating the two adjacent white patches of
enlarged precloacal scales . Two pairs of rounded, cloacal
spurs present on either sides of the hemipenal bulge. Six
precloacal pores present around the precloacal groove.
Thigh short (FEL:SVL 0.17); scales on ventral surface of
the thighs s mooth. Tibia s lightly longer than the thighs
(TBL:SVL 0.18); feet shorter than the thighs . Toes
curved and elongated with 19 subdigital lamellae under
toe IV; of which, the basal six are slightly dilated and the
rest undilated; relative lengths of toes IV>III>V>II>I;.
Upper arm shorter than lower arm (UAL:LAL 0.81);
palm shorter than lower arm; relative length of fingers
IV>III>V>II>I. Dors al colouration brown with 7-8 dark
brown relatively slender transverse bars on the trunk that
are narrower than the ground colour. A dis tinct, U-
shaped band (the nuchal loop) from behind the eyes to
the nape. Tail with dark transverse bands ; underside uni-
form creamy yellow. Enlarged precloacal scales bright
white in colour. Measurements of the examined speci-
mens are in table 2.
Variation: Females lack the pale skin patch in the
precloacal region and precloacal pores. Two s mall,
rounded cloacal spurs located near the sides of the vent in
males. Measurements of the studied specimens are in
table 2.
Distribution: C. rubidus occurs throughout most islands
of the Andaman archipelago and was recorded from the
following islands: South Andaman, Middle Andaman,
Baratang, North Andaman, Little Andaman, Havelock,
Neil, Kyd, Rutland, Interview, North Reef, Paget, Tar-
mugli, Long, North Passage and Guitar. It has also been
recorded from far and distant ones such as Narcondam
(Raman et al., 2013). Records during the present study
are in figure 10.
Natural His tory: Commonly found in forests as well as
human habitation. Nocturnal and feeds on insects. Ophid-
ian predators such as Lycodon hypsirhinoides were often
seen feeding on C. rubidus.
Cyrtodactylus nicobaricus sp. nov. (Figures 3-4; Table 2)
Cyrtodactylus rubidus (nec Blyth, 1861) – Bis was &
Sanyal, 1984: 477
Cyrtodactylus adleri (nec Das, 1997) – Harikrishnan &
Vas udevan, 2018
Holotype: ZSI/ANRC/T/ 11074), an adult male, col-
lected by S.R. Chandramouli from human habitation in
Chuckchucka Village (9.21º N, 92.79º E, 33.4 m asl.) in
Car Nicobar Is land on 17 June 2017.
Paratopotypes : DOSMB05100, an adult female and
DOSMB05101, an adult female, collected by S.R.
Chandramouli from the type locality on 13 and 15 June
2017 res pectively.
T wo new species from the Nicobar Islands
80
C. rubidus C. nicobaricus
sp. nov.
C. camortensis sp.
nov. C. adleri
SVL 48.59-56.75 45.77-50.77 53.41-63.75 42.13-62.8
trans verse tubercles 13-15 16-18 16-18 18-20
Supralabials 10-11 10 11 10-11
Infralabials 9 8-9 8-9 8-10
Precloacal groove present present absent absent
Ventrals juxtapos ed imbricate juxtapos ed imbricate
Subdigital lamellae 17-19 14-15 19-21 18-20
Nuchal loop pattern present present absent absent
Dors al pattern banded banded spotted spotted
Table 1. Comparison of morphological characters between Cyrtodactylus spp. of the A&N Is lands
AJCB Vol. 9 No. 1, pp. 78–89, 2020
Chandramouli
81
Voucher No: ZSI/ANRC/
T/ 11074 DOSMB05100 DOSMB05101 mean DOSMB05047 DOSMB05073 DOSMB05069 mean
Species Cyrtodactylus nicobaricus sp. nov. Cyrtodactylus rubidus
Sex m f f f m m
SVL (mm) 45.77 46.47 50.77 47.67 56.75 48.59 56.07 53.80
Trunk length 15.21 17.04 19.79 17.35 24.88 21.83 23.4 23.37
Tail 53 35.77 27.35 38.71 65 61 72 66.00
Head length 14.12 14.73 15.11 14.65 15.68 13.86 16.41 15.32
Head width 9.43 8.7 9.23 9.12 10.88 9.07 11.1 10.35
Head depth 5.52 5.66 5.44 5.54 6.79 5.98 7.47 6.75
Eye dia 3.56 2.73 3.74 3.34 3.75 3.02 4.16 3.64
Tympanum dia 0.73 0.65 0.88 0.75 0.83 0.86 0.67 0.79
Eye- nostril 4.65 4.7 5.04 4.80 4.91 4.33 4.96 4.73
Eye - s nout 6 5.96 6.13 6.03 6.9 5.88 6.75 6.51
Eye - tympanum 4.44 4.46 4.48 4.46 4.58 4.2 5.09 4.62
Supalabials 10 10 10 - 10 10 11 -
Infralabials 8 9 8 - 9 9 9 -
Ventrals 38 37 40 - 38 39 40 -
Upper arm length 5.36 5.91 6.09 5.79 7.74 7.43 6.25 7.14
Lower arm length 5.9 6.22 7.17 6.43 7.66 5.89 7.72 7.09
Palm length 5.42 5.71 5.38 5.50 5.58 5.4 6.38 5.79
Femur length 8.75 10.25 8.88 9.29 11.09 8.63 9.73 9.82
Tibia length 8 8.42 8.14 8.19 10.61 8.85 10.11 9.86
Foot length 6.96 7.11 7.34 7.14 7.8 7.62 8.89 8.10
T4 lamellae 14 15 14 - 17 17 19 -
F1 1.17 1.14 1.6 1.30 2.1 1.96 2.05 2.04
F2 1.62 2.52 2.06 2.07 3.35 3.16 3.34 3.28
F3 2.87 3.38 2.86 3.04 4.25 3.46 3.92 3.88
F4 3.76 3.66 3.21 3.54 4.32 4.02 4.31 4.22
F5 2.48 2.86 2.44 2.59 3.56 3.67 3.77 3.67
T1 1.29 1.72 1.53 1.51 2.38 1.76 2.7 2.28
T2 2.44 3.42 2.41 2.76 3.8 3.96 4.31 4.02
T3 4.18 4.65 3.58 4.14 5.3 4.63 5.22 5.05
T4 4.7 4.7 4.19 4.53 5.47 4.78 5.23 5.16
T5 4.33 4.54 3.88 4.25 3.95 4.37 5.04 4.45
Post-mentals 2+2 2+2 2+2 2+2 2+2 2+2
Table 2. Measurements and morphological characters of Cyrtodactylus spp. of the A&N
continued
AJCB Vol. 9 No. 1, pp. 78–89, 2020
T wo new species from the Nicobar Islands
82
Voucher No: DOSMB05016 DOSMB05024 DOSMB05057 ZSI/ANRC/
T/ 11076 mean ZSI/ANRC/
T/ 11075 DOSMB05083
Species Cyrtodactylus adleri Cyrtodactylus camortensis sp. nov.
Sex f m m m m f
SVL (mm) 42.13 55.93 52.56 62.8 53.35 53.41 63.75
Trunk length 16.95 22.67 19.43 25.62 21.16 23.75 24.74
Tail 40 65 67 46.39 54.59 64 52
Head length 12.5 16 14.61 17.32 15.1 15.74 17.01
Head width 7.25 10.21 9.04 11.02 9.38 10.64 11.28
Head depth 5.04 6.47 5.57 6.91 5.99 6.5 6.9
Eye dia 2.92 3.52 3.75 4.32 3.62 3.67 4.33
Tympanum dia 0.75 0.87 0.7 0.67 0.74 0.88 1.02
Eye- nostril 3.01 4.81 4.97 5.41 4.55 5.52 6.02
Eye - s nout 4.62 6.79 6.12 6.88 6.1 6.92 7.66
Eye - tympanum 3.65 4.77 3.68 5.32 4.35 5.27 5.62
Supalabials 11 10 10 11 - 11 11
Infralabials 10 9 8 8 - 8 9
Ventrals 46 48 47 50 - 47 49
Upper arm length 5.4 7.52 7.3 8.45 7.16 7.52 8.58
Lower arm length 4.95 8.23 7.53 9.27 7.49 7.3 8.67
Palm length 5.04 6.67 6.4 5.92 6.0 6.63 6.3
Femur length 7.16 11.17 8.86 11.85 9.76 9.72 10.02
Tibia length 7.61 10.11 9.64 10.07 9.35 9.45 10.47
Foot length 6.54 8.06 8.73 9.53 8.21 9.61 9.04
T4 lamellae 19 18 20 18 - 21 19
F1 1.2 2.32 2.95 2.35 2.2 2.15 2.46
F2 2.13 3.06 3.57 3.73 3.12 4.11 3.13
F3 2.64 3.76 4.82 4.28 3.87 4.32 4.92
F4 3.28 4.28 4.76 4.21 4.13 4.33 4.93
F5 2.95 3.37 3.73 3.82 3.46 3.67 4.01
T1 1.95 2.3 2.06 2.63 2.35 3.19 3
T2 2.52 4.05 3.91 4.82 3.82 4.85 4.37
T3 4.25 4.86 5.15 5.35 4.9 5.66 5.32
T4 4.67 4.85 5.16 5.84 5.13 5.98 5.57
T5 3.94 4.6 5.16 5.38 4.77 5.3 5.66
Post-mentals 2+2 2+2 2+2 2+2 2+2 2+2
Table 2. Measurements and morphological characters of Cyrtodactylus spp. of the A&N (continued)
AJCB Vol. 9 No. 1, pp. 78–89, 2020
Differential diagnosis and comparisons: (Table 1, Fig-
ure 5)
A Cyrtodactylus endemic to Car Nicobar Island of the
Nicobar archipelago which is diagnosed and character-
ized by: presence of 16–18 transverse rows of dorsal tu-
bercles (vs. 13–15 in C. rubidus); 10 supralabials , eight–
nine infralabials, two elongate inner pair of post-mentals
in broad contact with each other; two smaller outer pair
of post-mentals separated from each other; presence of a
precloacal groove (vs. absent in C. adleri and C. camort-
ensis sp. nov.) and upto six precloacal pores located
around the precloacal groove in males; abs ence of femo-
ral pores; presence of four enlarged internas als; presence
of ventrolateral dermal folds; 37–40 strongly imbricate
ventrals (vs . juxtaposed and non-overlapping ventrals in
C. rubidus); two pairs of rounded cloacal spurs in males;
14–15 subdigital lamellae under the IV toe of which, the
basal six are slightly dilated (vs. 17–19 in C. rubidus);
presence of a dark nuchal loop formed by post ocular
streaks extending and joining at the nape (vs. absent in C.
adleri and C. camortensis sp. nov.); dors al colour pattern
of five to six dark transverse bands on a dark brown
ground colour (vs . a series of vertebral spots in C. adleri
and C. camortensis sp. nov.) with a series of short longi-
tudinal bands converging posteriorly towards mid-
dorsum between forelimbs.
Des cription of holotype: ZSI/ANRC/T/ 11074
A medium sized adult male measuring 45.77 mm SVL.
Head longer than broad (HL:HW 1.5) with a rounded
snout tip. Eyes large with a vertically elliptical pupil,
(ED:HL 0.25) but shorter than the snout. Habitus de-
pressed; with a long trunk (AG 15.21). Supralabials
10/10, infralabials 8/8; mental triangular and broad
bounded by two pairs of pos t-mentals . Inner pair in con-
tact with each other; s lightly larger than the outer pair.
Dors um covered by smooth, rounded tubercles of inter-
mixed size; in 17 transverse rows . Ventrals imbricate,
overlapping with each other, with a blunt, rounded poste-
rior vertex. Venter cream coloured with small black spots
scattered all throughout. Precloacal groove and cloacal
spurs evident; s ix precloacal pores located around the
precloacal groove situated in the middle of the large,
brightly coloured patch of scales . Thigh short (FEL:SVL
0.19); tibia s lightly shorter than thighs (TBL:SVL 0.17);
foot longer than thigh, with long curved digits lacking
dilations. Relative length of toes IV>III>V>II>I; 14 sub-
digital lamellae under toe IV, of which the basal six are
slightly dilated. Upper arm slightly shorter than lower
arm (UAL:LAL 0.91); palm shorter than lower arm; rela-
tive length of fingers IV>III>V>II>I. Dors al colouration
greyish brown overall, with a series of five thick trans-
verse bars across the body, which are about as broad as
the spaces in between them. A dark, U shaped band, the
nuchal loop present from behind the eyes to the nape.
The first band on the trunk bordered by s hort longitudinal
lines. Original tail complete and has a dis tinct, alternating
light and dark banded pattern.
Variation: The female paratypes lack an obvious
hemipenal bulge or a precloacal groove. Two small,
rounded cloacal spurs located near the s ides of the vent in
Chandramouli
83
Figure 3. Cyrtodactylus nicobaricus sp. nov. Above:
Holotype ZSI ZSI/ANRC/T/ 11074; below: living indi-
viduals from Car Nicobar
Figure 4. (A) dorsal and (b) ventral views of head, (c)
dorsal and (d) ventral views of the trunk, (e) ventral view
of the right foot and (f) precloacal region of a paratype
(DOSMB05100) of Cyrtodactylus nicobaricus sp. nov.
AJCB Vol. 9 No. 1, pp. 78–89, 2020
male. Male slightly s maller than the two females . Meas-
urements of the paratypes are in table 2.
Distribution: Cyrtodactylus nicobaricus sp. nov. is en-
demic to Car Nicobar and possibly Batti Malv, the north-
ern group of the Nicobar Is lands . Recorded only from
Car Nicobar during this study and its presence or ab-
sence on the smaller, adjacent Batti Malv Island is not
known.
Natural History: A common species found in fores ts as
well as human habitation. Often observed on leaf-litter in
the forest floor and branches of small shrubs up to about
1m above the ground. Nocturnal and feeds on insects.
Etymology: A toponym, named after the type locality of
this species, Car Nicobar Is land, which is colloquially
called just as ‘Nicobar’.
Cyrtodactylus camortensis sp. nov. (Figures 6-7; Table 2)
Cyrtodactylus adleri (nec Das, 1997) – Harikrishnan &
Vas udevan, 2018
Holotype: ZSI/ANRC/T/ 11075, an adult male, collected
by S.R. Chandramouli on 27 July 2017 from human
habitations near Changua Village (8.018N, 93. 494 E,
140 m as l.), Camorta, Central group of the Nicobar Is -
lands.
Paratopotype: DOSMB05083, an adult female, col-
lected by S.R. Chandramouli from the same locality on
28 July 2017.
T wo new species from the Nicobar Islands
84
Figure 5. PCA plot showing the relative distribution of Cyrtodactylus spp. of the A&N Is lands: Cyrtodactylus
rubidus (red squares ) from the Andaman archipelago; Cyrtodactylus nicobaricus sp. nov. (purple squares) from
Car Nicobar; Cyrtodactylus camortensis sp. nov. (green triangles ) from central Nicobar Is lands and Cyrtodacty-
lus adleri (blue triangles) from southern Nicobar Islands.
Figu re 6. Cyrtodactylus camortensis sp. nov. Above: Holotype
ZSI/ANRC/T/ 11075 in preservation; middle and belo w: Cyrto-
dactylus camortensis in life from Camorta
AJCB Vol. 9 No. 1, pp. 78–89, 2020
Differential diagnosis and comparisons: (Table 1)
A Cyrtodactylus endemic to the central group of the Ni-
cobar Islands, characterized by: presence of 16-18 trans-
verse rows of dors al tubercles (vs . 13–15 in C. rubidus);
11 s upralabials, eight to nine infralabials , two elongate
inner pair of post-mentals in broad contact with each
other; two s maller outer pair of post-mentals s eparated
from each other; absence of a precloacal groove (vs . pre-
sent in C. rubidus and C. nicobaricus sp. nov.) and upto
seven precloacal pores in males; abs ence of femoral
pores; presence of four enlarged internasals; 47–49 jux-
taposed ventrals (vs. strongly imbricate ventrals in C.
adleri and C. nicobaricus sp. nov.); two pairs of rounded
cloacal spurs in males; 19–21 subdigital lamellae under
the IV toe, of which the basal s even are slightly dilated
(vs. 17–19 in C. rubidus; 14–15 in C. nicobaricus sp.
nov.; 19–20 C. adleri); absence of a dark nuchal loop
formed by post ocular streaks extending and joining at
the nape (vs. present in C. rubidus and C. nicobaricus sp.
nov.; dors al colour pattern of dark vertebral spots,
bounded by lateral streaks (vs. 5–6 dark transverse bands
on a dark brown ground colour in C. rubidus and C. ni-
cobaricus sp. nov.).
Des cription of holotype (ZSI/ANRC/T/ 11075):
A fairly large adult male measuring 55.93 mm SVL.
Head fairly large (HL:SVL 0.29); longer than broad
(HL:HW 1.48) with a rounded snout tip. Eyes large
(ED:HL 0.23) with a vertically elliptical pupil. Habitus
depressed; with a long trunk (AG 23. 75). Supralabials
11/11, infralabials 8/8; mental wedge-shaped and fairly
long, bounded by two pairs of pentagonal post-mentals.
Inner pair in contact with each other; s lightly larger than
the separated outer pair. Dorsal tubercles s mooth, in 16
trans verse rows, s lightly enlarged and relatively much
smaller than in the other species . Ventrals circular in
shape, non-overlapping and juxtaposed, in 49 rows
across the belly. Venter pale white with each ventral
scale bearing small black spots. Precloacal groove absent,
but a pinkish patch with distinctly enlarged precloacal
scales occur, within which seven precloacal pores are
present. Femoral pores absent. Thigh short (FEL:SVL
0.18); tibia as long as the thigh (FEL:TBL 1.0); foot
slightly shorter than thigh. Hemipenal bulge and rounded
cloacal spurs distinct. Toe IV with 21 lamellae, of which
the basal seven are s lightly dilated. Relative length of
toes IV>V>III>II>I. Upper arm slightly longer than
lower arm (UAL: LAL – 1.03); palm s horter than lower
arm; relative lengths of fingers : IV>III>II>V>I. Left
hand lacking palm, presumably due to injury. Dors al col-
oration grayish brown with a series of 7 dark spots with
confluent short lateral bands . A short, broken V shaped
marking on the nape. Tail with dark annuli; venter pale
white in colour.
Variation: The female paratype shows a striking contrast
in colouration by being bright yellowish with large dark
brown circular dorsal blotches. However, this variation is
not sex specific, as an adult male of such colouration was
also recorded from Katchall. Measurements of the para-
types are in table 2.
Distribution: Cyrtodactylus camortensis is endemic to
the central group of islands within the Nicobar archipel-
ago and was recorded from Camorta, Katchall, and Nan-
cowry Is lands. However, it could potentially occur in the
other Is lands of this group such as Chowra, Teressa,
Bompoka and Tillanchong.
Natural History: An uncommon species found in forests
as well as human habitation. Seen frequently on the
ground, roads and culverts alongside. Nocturnal and
feeds on insects.
Etymology: A toponym, named after Camorta Island, the
type locality of this species.
Cyrtodactylus adleri Das , 1997 (Figures 8-9; Table 2)
Type material: ZSI 25057 (holotype) from ‘1 km E Ga-
lathea River mouth, Great Nicobar’; ZSI 25059 – 25061;
ZSI 23398, ZSI 25117 (paratypes ), all from Great Ni-
cobar.
Material examined: DOSMB05016 and DOSMB05024
– Great Nicobar, DOSMB05057, ZSI/ANRC/T/ 11076 –
Little Nicobar
Differential diagnosis and comparisons: (Table 1)
Cyrtodactylus adleri is endemic to the southern group of
islands in the Nicobar archipelago and is characterized
by: moderate adult body size (SVL 42.13–62.8 mm);
intensely tuberculate dorsum (18–20 transverse rows at
midbody); 10–11 supralabials; 8-10 infralabials; two
elongate inner pair of post-mentals in broad contact with
each other; two smaller, separated outer pair of post-
mentals; absence of a precloacal groove (vs. present in C.
rubidus and C. nicobaricus sp. nov.) and upto s ix
Chandramouli
85
Figure 7. (A ) dorsal and (B) ventral views of head, (C)
dorsal and (D) ventral views of the trunk, (E) ventral
view of the right foot and (F) precloacal region of the
holotype Cyrtodactylus camortensis sp. nov.
AJCB Vol. 9 No. 1, pp. 78–89, 2020
precloacal pores in males; presence of 4 enlarged inter-
nasals; 46–50 transverse rows of imbricate ventrals (vs.
juxtapos ed in C. rubidus and C. camortensis sp. nov. );
20–23 transverse rows of keeled triheadral dorsal tuber-
cles ; two pairs of rounded cloacal spurs in males; 18–20
subdigital lamellae under the IV toe; absence of a nuchal
loop formed by post ocular streaks extending and joining
at the nape and a dorsal colour pattern of dark vertebral
spots, bounded by lateral streaks (vs. 5–6 dark transverse
bands on a dark brown ground colour in C. rubidus and
C. nicobaricus sp. nov.).
Des cription of a topotype (DOSMB05024):
An adult male, measuring 55.93 mm SVL. Head large,
(HL:SVL 0.28); longer than broad(HL:HW 1.57) with a
rounded snout tip. Eyes large (ED:HL 0.2); with a verti-
cally elliptical pupil. Habitus depressed with a long trunk
(AG 22.67). Supralabials 10/10; infralabials 9/9; mental
short, as broad as long. Post-mentals in two pairs , inner
pair larger and in contact with each other, outer pair
small and separated. Dors al tubercles large and triheadral
with a longitudinal keel; in 18 transverse rows at mid-
body. Ventrals imbricate, in 48 transverse rows, rhom-
boidal in shape and imbricate, overlapping with each
other. Precloacal groove absent, but a pale patch of dis-
tinctly enlarged precloacal scales present, within which
six precloacal pores occur. Two small, rounded colacal
spurs pres ent. Femoral pores abs ent. Thigh short
(FEL:SVL 0.2); s lightly longer than the tibia (TBL:SVL
0.18); foot s horter than thigh. Toes curved and bear 18
subdigital lamellae under toe IV, of which the basal eight
are slightly dilated. Relative length of toes
V>IV>III>II>I . Upper arm slightly shorter than lower
arm (UAL:LAL 0.91); palm a little shorter, with curved
fingers bearing undilated subdigital lamellae. Relative
length of fingers IV>V>III>II>I. Dorsum grey brown
with dark brown spots along the vertebra. A ‘V’ shaped
mark on the nape bordered by two dark longitudinal
streaks till the axilla. Tail annulated with dark bands.
Variation: Males larger than females, which lack preclo-
acal pores. Gravid females had two eggs discernible in-
side the belly. Measurements of the examined specimens
are in table 2.
Distribution: Recorded from Great Nicobar and Little
Nicobar Islands during this study and could potentially
occur on small, adjacent is lands such as Pilo Milo, Kon-
dul and Menchal.
Natural His tory: A common species found in forests as
well as human habitation. Nocturnal and feeds on insects.
Observed frequently in the forests, mos tly on stems of
shrubs.
DISCUSSION
The present study reveals an underestimated diversity of
Cytrodactylus geckos within the Andaman and Nicobar
archipelago until now, which is in line with the vast num-
ber of new species discoveries made throughout most
T wo new species from the Nicobar Islands
86
Figure 8. Cyrtodactylus adleri from Great Nicobar
(above); Little Nicobar (below).
Figure 9. (A) dorsal and (b) ventral views of head, (c)
dorsal and (d) ventral views of the trunk, (e) ventral view
of the left foot and (f) precloacal region of Cyrtodactylus
adleri DOSMB05024.
AJCB Vol. 9 No. 1, pp. 78–89, 2020
parts of the range of this genus (e.g. Pauwels et al. 2016;
Oliver et al., 2019; Quah et al., 2019; Grismer et al.,
2015; Zeigler et al., 2013; Grismer et al., 2008; Grismer
et al., 2018b, Nazarov1 et al., 2018; Grismer et al.,
2019). Since Blyth (1861) described C. rubidus from the
Andaman Is lands, there had been a vast gap of 136 years
in-between until the description of the s econd species, C.
adleri by Das (1997). The pres ent discovery of two new
species from other parts of these islands after a gap of 22
years , despite several surveys for herpetofauna con-
ducted here in the past (e.g. Das, 1999; Vijayakumar,
2005; Harikrshnan and Vas udevan, 2018) is significant.
Though Vijayakumar (2005) reported unidentified popu-
lations of Cyrtodactylus spp. on islands of the northern
and central group of the Nicobar Islands, no attempt has
been made towards attaining a systematic resolution until
now. On the other hand, Harikrishnan and Vasudevan
(2018) referred the northern and central Nicobar popula-
tions to C. adleri without any justification. The present
study has revealed that C. adleri is in fact, restricted to
the southern group of the Nicobar Is lands and the species
occurring to the north of its range represent hitherto un-
described populations as evidenced by their differing
morphology and allopatric distribution, as detailed above.
This has a direct impact on the implications drawn by
Harikris hnan and Vas udevan (2018) who presumed
‘positive co-occurrence’ of other lizard species such as
Bronchocela rubrigularis, Dasia nicobarensis and Gekko
nicobarensis with C. adleri while dealing with its niche.
Because of their mis conception of C. adleri, such errone-
ous conclus ions have been drawn. Likewis e, Agarwal et
al. (2014:147) in their study on biogeography of
Chandramouli
87
Figure 10. Map of the Andaman & Nicobar archipelago showing the distribution of: Cyrtodactylus rubidus (red:
Andaman Is lands); C. nicobaricus sp. nov. (yellow: Car Nicobar); C. camortensis sp. nov. (central Nicobars : blue)
and C. adleri (black: Little & Great Nicobar).
AJCB Vol. 9 No. 1, pp. 78–89, 2020
naked-toed geckos, referred a sample of Cyrtodactylus
from Nancowry Island to C. adleri, which is now refer-
able to C. camortensis sp. nov.
Among these, C. rubidus, the earliest known
species from the Andaman archipelago shows the widest
distribution within these islands occurring throughout
most parts of the Andaman archipelago. The newly de-
scribed Cyrtodactylus nicobaricus sp. nov. probably has
the most narrow geographic distribution range within the
archipelago, being restricted only to Car Nicobar, situ-
ated at the northern region of the Nicobar archipelago
(Figure 10). The other species, C. camortensis sp. nov.
and C. adleri, although restricted to a few small islands,
have a relatively wider distribution range in comparison
to C. nicobaricus sp. nov. Though spatially compact and
proximate, lots of intrinsic biogeographic variations
within the Nicobar archipelago have been well estab-
lis hed (Das , 1999; pers. obs ). The distribution pattern of
Cyrtodactylus geckos in the Nicobar archipelago roughly
reflects the distribution pattern of agamids of the genus
Bronchocela in this region, with B. cf. cristatella being
restricted to Car Nicobar; B. rubrigularis to the islands
of the central group and B. danieli in Great Nicobar Is-
land, situated to the south. Among these, conservation
status has been assessed only for C. adleri as Least Con-
cern (Böhm and Dewhurst, 2010). Going by the IUCN
criteria B1 and B2, the two new species described here
would fall under the category of endangered species
(extent of occurrence < 5000 km
2 and area of occupancy
< 500 km2). The Andamanes e species C. rubidus would
fall under the least concerned category as it occurs on
most of the is lands throughout the Andaman archipelago.
Although fairly common within their respective distribu-
tion ranges , these geckos face competition for space and
resources from other nocturnal, insectivorous species
with similar body sizes but relatively wider geographic
ranges such as Hemidactylus spp. and Gehyra mutilata.
Thes e species often tend to get introduced easily to new
areas by transportation through human agency (e.g.
Chandramouli, 2015; Gokulakris hnan et al., 2019) and
therefore, pose a threat to the native Cyrtodactylus
geckos.
Key to Cyrtodactylus species of the Andaman and
Nicobar Islands:
A) Precloacal groove pres ent
1. ventrals juxtaposed, 17-19 subdigital lamel-
lae under toe IV…... C. rubidus
2. ventrals imbricate, 14-15 subdigital lamellae
under toe IV……. C. nicobaricus sp. nov.
B) Precloacal groove absent
1. ventrals juxtaposed, 19-21 subdigital lamel-
lae under toe IV, 16-18 transverse
rows of small, rounded tubercles on mid-
dorsum………………C. camortensis sp. nov.
2. ventrals imbricate, 18-20 subdigital lamellae
under toe IV, 18-20 transverse
rows of large, keeled tubercles on mid-
dorsum…………………C. adleri
ACKNOWLEDGEMENTS
I thank the Department of Environment and Forests, An-
daman and Nicobar Islands for permiss ion (permit nos:
CWLW/WL/134/(J)/Folder/417 and CWLW/WL/134
(L)/ 60) to conduct this study and for the infrastructure
provided. I am thankful to Prof. K. V. Devi Prasad and
the faculty of the Dept. of Ecology and Environmental
Sciences and the Dept. of Ocean studies and Marine Bi-
ology, Pondicherry University for the lab space and sup-
port extended. Constructive comments by Lee Grismer
are appreciated.
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