Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2023 | 15(10): 24120–24124
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8612.15.10.24120-24124
#8612 | Received 24
June 2023 | Final received 26 September 2023 | Finally accepted 03 October 2023
New locality record of Forest
Spotted Gecko Cyrtodactylus (Geckoella) cf. speciosus
(Beddome, 1870) (Reptilia:
Squamata: Gekkonidae) from Thanjavur,
in the eastern coastal plains of Tamil Nadu, India
Gopal Murali 1
1 IISER-TVM Center for Ecology and
Evolution (ICREEE), School of Biology, Indian Institute of Science Education
and Research Thiruvananthapuram, Maruthamala PO,
Thiruvananthapuram, Kerala 695551, India.
2 Current address: Department of
Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85719,
United States.
Editor: S.R. Ganesh, Kalinga Foundation, Agumbe, Karnataka, India. Date of publication: 26 October
2023 (online & print)
Citation: Murali, G. (2023). New locality record of Forest Spotted
Gecko Cyrtodactylus (Geckoella)
cf. speciosus (Beddome,
1870) (Reptilia: Squamata: Gekkonidae)
from Thanjavur, in the eastern coastal plains of
Tamil Nadu, India. Journal
of Threatened Taxa 15(10): 24120–24124. https://doi.org/10.11609/jott.8612.15.10.24120-24124
Copyright: © Murali 2023. Creative Commons Attribution 4.0 International License. JoTT allows
unrestricted use, reproduction, and distribution of this article in any medium
by providing adequate credit to the author(s) and the source of publication.
Funding: None.
Competing interests: The author declares no competing interests.
Acknowledgements: I thank
Murali G. and Lakshmi M. for their help in the field.
Abstract: The study of species distributions is critical
for gaining insights into biogeographic patterns and for the protection of
threatened species. Here, I report on the new distributional record of the
Forest Spotted Gecko (Cyrtodacylus cf. speciosus) from Thanjavur
in the coastal plains of Tamil Nadu. This observation marks the first
documented occurrence of this species outside its typical hilly habitat in
southern India.
Keywords: Eachankottai
Village, Erode Gecko, population, range extension, road cruising
surveys.
The Forest
Spotted Gecko or Erode Gecko Cyrtodactylus speciosus (Beddome, 1870) was
described initially as Gymnodactylus speciosus without precise locality information from “a
tope near Erode,” in Erode District, Tamil Nadu, India (Beddome
1870). Smith (1935) listed this species as a color variant of Gymnodactylus collegalensis
Beddome, 1870 and noted that its range is
limited to low-elevation sites in the hills of southern India. Agarwal et al.
(2016) subsequently recognized this species as Cyrtodactylus
speciosus based on comparisons with the damaged
type specimen and molecular data collected from individuals at Coimbatore North
Taluk, Coimbatore District, Tamil Nadu. This species is yet to be collected
from the type locality, Erode. Cyrtodactylus
speciosus is also reported from three other
locations in the southern Eastern Ghats (Jawadhu, Shevaroy, and Kolli hills; Table
1). Further, this species or a closely related lineage is known to occur in Sirumalai Hills, Dindigul
District, Tamil Nadu (Ganesh & Arumugam 2016). However, these records were
based on photo vouchers alone, whereas persevered voucher specimens and tissue
samples for genetic data would have ideally been the preferred case. Here,
based on photo vouchers, I report the easternmost locality of Cyrtodactylus cf. speciosus
from Thanjavur, in the coastal plains of Tamil Nadu.
On 12 July
2014 at 1952 h, I encountered a live adult Cyrtodactylus
cf. speciosus crossing a road near Eachankottai Village, Thanjavur,
Tamil Nadu (10.6490oN, 79.1492oE; Figure 1). This
individual was identified to be a male (based on hemipenal
bulge) with a snout-vent length (SVL) of 47 mm. I encountered another male
gecko with a SVL 43 mm on 10 June 2022 at 2037 h from
the same road (10.6529oN, 79.1500oE; Image 1). Both
individuals were visually similar to C. speciosus,
as described by Agarwal (2016) and Agarwal et al. (2016). The characters
noted in the two individuals include two interorbital spots, an elongated interparietal streak longer than two interoccipital spots,
a deeply notched post-occipital collar (separated from the postorbital streak
in one of the two individuals; Image 1), and two brown dorsal bands
between limb insertions with the black border of the bands slightly notched
(Image 1). The geckos made squeaking calls when handled for the first
time, as observed in other Geckoella group
(Agarwal et al. 2016). The geckos were photographed, measured, and released at
the capture site. Other geckos observed in this location include the
widespread, common, and human-commensal ones, viz., Hemidactylus
cf. parvimaculatus, H. triedrus,
H. frenatus, and H. leschenaultii.
Hemidactylus scabriceps,
another dryland specialist that shares ecological characteristics of C. speciosus (strictly ground-dwelling and nocturnal), is
also known to occur in Thanjavur (Srikanthan
et al. 2018). However, I have not seen H. scabriceps
from this location. The only nearby sighting of H. scabriceps is about ca. 20 km from the current location
(10.7958oN, 79.0589oE).
The habitat
adjacent to the road where the geckos were found consists mainly of open arid
scrublands and thorn forests—Deccan thorn scrub forest ecoregion—according to
Olson et al. (2001). These are bordered by plantation trees along both sides of
the road (Image 2). This land area is a part of the district’s exotic cattle
breeding farm, established by the Government of Tamil Nadu in 1954, and part of
it has remained unaltered since then. Regions immediately surrounding the farm
are dominated greatly by agricultural land, mostly cashew and sugarcane fields.
I further conducted extensive road cruising surveys in nearby potentially
suitable habitats within a ca. 25 km radius surrounding the sighted locality.
However, I did not find any Cyrtodactylus spp.
This indicates that species is probably sensitive to habitat modification and
that the population is likely confined to the unmanaged arid scrublands within
the cattle farm, encompassing about 5.6 km2 in total, with native
scrubland occupying no more than 2.6 km2. The currently reported
locality does not strictly fall under any protected area network. However, the
entire farm area is fenced (Image 2), and outsiders are not allowed without
permission. Nevertheless, this region seemed to have been occasionally used by
locals for cattle grazing. The present sighting of such an apparently
habitat-specific gecko (Agarwal et al. 2016) suggests that such habitat patches
like in Eachankottai require greater protection, as
they harbor greater biodiversity than the surrounding farmlands, in as far as
is known.
Cyrtodacylus speciosus has been
assigned to the ‘Endangered’ category by the IUCN, and the species population
status is assessed to be in decline due to habitat loss and fragmentation (Achyuthan et al. 2021). This new easternmost locality for C.
cf. speciosus is ca. 112 km south-west of
the nearest known locality at Kolli Hills, Tamil
Nadu, and 173 km from the type locality Erode (Figure 1). Nevertheless, it
remains unclear if C. speciosus is actually a
single widespread species or a group of closely related species (Agarwal et al.
2023a). All members of the C. collegalensis
complex, except C. varadgirii and the recently
described C. chengodumalaensis, have been
documented only in hilly landscapes of southern India (Agarwal et al. 2023b).
The newly documented location is situated at an elevation of 24 m, about 65 km
from the nearest hillock. Further, this location is ~45 km from the nearest
coastline. The current distribution locality thus marks the first occurrence
record of this species complex outside their typical hilly terrain in
southern India in addition to imprecise type locality (‘Erode’). It is possible
that the Cyrtodactylus cf. speciosus population reported here could be an
entirely distinct lineage. Hence, further genetic sampling may help assess its
evolutionary relationship with other arid zone Cyrtodactylus
species and help resolve the biogeographic history of this species complex.
Table 1. Published locality
records and corresponding districts where Cyrtodactylus
speciosus and Cyrtodactylus
cf. speciosus have been reported from Tamil
Nadu.
|
Locality |
District |
Reference |
|
‘Tope near Erode’ |
Erode |
Beddome 1870 |
|
Coimbatore North Taluk |
Coimbatore |
Agarwal et al. 2016 |
|
Jawadhu hills |
Tiruvannamalai |
Ganesh & Arumugam 2016 |
|
Shevaroy hills |
Salem |
Ganesh & Arumugam 2016 |
|
Kolli hills |
Namakkal |
Ganesh & Arumugam 2016 |
|
Sirumalai hills (Cyrtodactylus cf. speciosus) |
Dindigul |
Ganesh & Arumugam 2016 |
|
Eachankottai village (Cyrtodactylus cf. speciosus) |
Thanjavur |
Present note |
For
figure & images - - click here for full PDF
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