Disentangling vines: a study of morphological crypsis and genetic divergence in vine snakes (Squamata: Colubridae: Ahaetulla) with the description of five new species from Peninsular India
Author
Mallik, Ashok Kumar
Author
Srikanthan, Achyuthan N.
0000-0003-0570-3330
peltopelor@gmail.com
Author
Pal, Saunak P.
0000-0002-8267-4708
herps.saunak@gmail.com
Author
D’Souza, Princia Margaret
0000-0002-2185-2611
princiadsouza777@gmail.com
Author
Shanker, Kartik
0000-0003-4856-0093
kshanker@gmail.com
Author
Ganesh, Sumaithangi Rajagopalan
0000-0002-1947-8093
snakeranglerr@gmail.com
text
Zootaxa
2020
2020-11-06
4874
1
1
62
journal article
8009
10.11646/zootaxa.4874.1.1
d04aa5ef-c604-457c-92e8-e8c9a88a1eef
1175-5326
4423512
8FF98990-0E47-4BB7-82BB-098F86771271
Ahaetulla sahyadrensis
nom. nov.
Passerita mycterizans
var.
fuscus
(not of
Duméril, Bibron & Duméril, 1854
)—
Günther, 1858
;
Beddome, 1862
Dryophis pulverulentus
(not of
Duméril, Bibron & Duméril, 1854
)—
Wall, 1919: 574
Dryophis pulverulenta indica
Deraniyagala, 1955
(non
Dryophis prasinus indicus
Mell, 1931
)
Ahaetulla indica
(
Deraniyagala, 1955
)
—nomen praoeccupatum pro
Ahaetulla indica
(
Mell, 1931
)
Ahaetulla sahyadrensis
nom. nov.
—nomen substitutum
Nomenclatural remarks.
As the Western Ghats population of
A. pulverulenta
sensu lato
is diagnosed to be distinct at species rank from the
Sri
Lankan population, the available subspecific nomen
Dryophis pulverulenta indica
Deraniyagala, 1955
listed as a subjective synonym, should be conferred on it. However, in the
Ahaetulla prasina
group, there is an available subspecific nomen
Dryophis prasinus indicus
Mell, 1931
. These nomina are available names and represent taxa that are currently considered congeneric (
Wallach
et al
. 2014
). Thus,
Dryophis pulverulenta indica
Deraniyagala, 1955
becomes a primary junior homonym of
Dryophis prasinus indicus
Mell, 1931
. As
Deraniyagala’s (1955)
nomen is junior to
Mell’s (1931)
nomen and is thus permanently invalid, and as both these nomina were originally erected at the same taxonomic rank (as subspecific nomina), we consider these nomina as congeneric. As no other subjective synonym is available for the preoccupied nomen (see
Wallach
et al.
2014
), according to Art. 57.2, 59.1 and 60.3 of the Code, we herein erect a new replacement name
Ahaetulla sahyadrensis
nom. nov.
to resolve this case of primary homonymy.
Type material and type locality.
As per Recommendation 60A of the Code, the new objective replacement nomen
Ahaetulla sahyadrensis
nom. nov.
takes the same type material and type locality as that of the preoccupied nomen
Dryophis pulverulenta indica
Deraniyagala, 1955
. Since no type specimen information has been given and the type locality is implied as
India
(
de Silva 1969
), here we designate a
neotype
and neoparatypes from the collections of
BNHS
from Peninsular
India
. As per Art. 75.3 of the Code (
ICZN
1999), since we clarify the status of this available nomen and since its name-bearing types are lost (
Wallach
et al.
2014
), we designate a
neotype
that is consistent with the original description (
Deraniyagala 1955
) and is in morphological and geographical conformity with the original publication.
Neotype
.
BNHS 2015
; Castle Rock,
Karnataka
;
Coll.
Gerhardt P.
, Year Unknown.
Neoparatypes.
BNHS
2012; Nelliyampathy hills;
Coll.
Kinloch A. M, 1911.
BNHS
2016; Karwar,
Karnataka
;
Coll.
McMann C., 1940.
CESS
159 adult
female Bhagavathi,
Kudremukh National Park
,
Karnataka
,
Coll.
Ashok Kumar Mallik
, 2010.
Comparative material.
Ahaetulla pulverulenta
:
SRI LANKA
:
BNHS
2009; adult (sex unknown); Ceylon (present day Sri Lanka);
Coll.
E.E. Green, Year unknown.
BNHS
2010; adult (sex unknown); Matugama,
Ceylon
(present day
Sri Lanka
);
Coll.
Col. Frank Wall, Year unknown.
BNHS
2011; adult (sex unknown);
Ceylon
(present day
Sri Lanka
);
Coll.
W.W.A Phillip., Year unknown.
Type locality (by virtue of
neotype
designation).
Castle Rock (
15.393 N
,
74.332 E
), in
Northern Western Ghats
,
Peninsular
India
.
Etymology.
Latin, toponym, alluding to its distribution in the Western Ghats or Sahyadri hills.
Diagnosis.
1. Phylogenetically,
Ahaetulla sahyadrensis
nom. nov.
(L7) is nested with the clade comprising
A. pulverulenta
(L8),
A. oxyrhyncha
comb. nov.
(L1) and
A. anomala
.
It is sister to the clade comprising
A. oxyrhyncha
comb. nov.
and
A. anomala
.
2. There is a low level (3.2 % in Cytb & 0.4 % in 16S) of genetic divergence between
A. sahyadrensis
nom. nov.
and members (CESS211, CESS244, CESS506, CESS521 & CESS528) of
Ahaetulla oxyrhyncha
(
Bell, 1825
)
comb. nov.
Ahaetulla anomala
also differs from
A. sahyadrensis
nom. nov.
with a low (3.2 % in Cytb and 0.8 % in 16S) level of genetic distance. In addition,
A. sahyadrensis
nom. nov.
shows a moderate level (4.52 % in Cytb and 1.7 % in 16S) of genetic divergence from
Sri
Lankan
A. pulverulenta
. Also,
A. sahyadrensis
nom. nov.
differs from the superficially similar, brown coloured
A. laudankia
as the latter belongs to a separate clade that clusters with Southeast Asian rather than South Asian taxa.
3. This is a species of usually grey-brown coloured
Ahaetulla
having an elongate multi-scaled rostral appendage and a rhomboid crown marking (vs. rostral scale not multi-scaled in all other sympatric
Ahaetulla
spp.; except
A. anomala
and
A. pulverulenta
); lacking white or yellow ventrolateral stripe (vs. present in all regional congeners except
A. pulverulenta
,
); 7 pre-diastemal and 6 post-diastemal maxillary teeth (vs. 7 and
9 in
A. isabellina
comb. nov.
, 6 and
7 in
A. malabarica
sp. nov.
, vs. 6 and
11 in
A. farnsworthi
sp. nov.
, vs. 6 and
8 in
A. borealis
sp. nov.
, vs. 7 and
7 in
A. oxyrhyncha
comb. nov.
& 8 and
7 in
A. pulverulenta
from
Sri Lanka
, dissected from BNHS 2010); differs from the northern Indian
A. laudankia
in having much lower ventral scale counts (vs. never less than
192 in
A. laudankia
), higher subcaudal scale counts (vs. never more than
185 in
A. laudankia
); differs from
A. pulverulenta
s. str.
(of
Sri Lanka
) in ventral scale counts 182–203 [
186–202 in
our study] (vs. 179–193 [
182–186 in
BNHS specimens] in
A. pulverulenta
s. str.
) and subcaudal scale counts 169–208 [
175–208 in
our study] (vs. 151–178 [
158–159 in
BNHS specimens] in
A. pulverulenta
s. str.
). The Sri Lankan
A. pulverulenta
specimens from BNHS also have 10–11 scale rows near the vent whereas
A. sahyadrensis
has 12–13 rows near the vent (
Fig. 11
&
12
,
Table 2
).
4. Being distributed in the Western Ghats, it is separated by a geographic barrier from
Sri
Lankan
A. pulverulenta
and is also separated from the lowland species
Ahaetulla oxyrhyncha
(
Bell, 1825
)
comb. nov.
and
A. anomala
by occupying a range in the wet hill-forest habitats.
Description of
neotype
.
Adult of total length
1765 mm
; dissected; very slender, partially laterally compressed body with snout to vent length
1054 mm
; tail length
711 mm
; ventrals 179 notched with keels; subcaudals 162 divid-ed; cloacal scale divided; relatively long and slender tail; dorsal scale rows in 15-15-11 rows of smooth, obliquely disposed scales; head very distinct from neck with head length
49.1 mm
; transversely oval eyes with horizontal pupil, with a horizontal diameter of
3.4 mm
and vertical diameter of
2.3 mm
; distance from nostril to eye
11.1 mm
; distance from snout tip to eye
18.3 mm
; supralabials 8 (both left and right) with 5
th
supralabial being the largest, in contact with the eye; 4
th
supralabial divided; infralabials 7 (both left and right); 2
nd
, 3
rd
and 4
th
infralabials in contact with the anterior genials; 4
th
and 5
th
infralabials in contact with the posterior genials; nasal 1 (both left and right); loreals absent; pre-subocular 2 (both left and right); pre-ocular 1 (both left and right); post-oculars 2; sub-oculars absent; temporal 3+3+1 (both left and right); prefrontal scale in contact with pre-oculars; preventrals 2; rostral appendage comprised of numerous smaller scales.
Variations shown by neoparatypes.
Ventrals 186–202, subcaudals 175–208, scale rows near the head 13–15, mid body 14–15 and near the vent 11–12.
Colour in life.
Dorsum with uniform light brown body with dark brown anteriorly-converging bars from nape till midbody; head with characteristic dark brown rhomboid markings, rostral appendage and eye stripe from the nostril to the nape dark brown; supralabials, infralabials and mentum white with brown spots of variable sizes; venter light brown, finely dotted with dark brown spots (
Fig. 11
h–k).
Colour in preservative.
Dorsum uniform light greyish brown body with anteriorly-converging brown bars from nape till midbody; head with dark brown rhomboid markings, rostral appendage and eye stripe from nostril to the nape brown; supralabials, infralabials and mentum white with faded brown spots of variable sizes; venter light brown, finely dotted with brown spots (
Fig. 11
a–g).
Hemipenis (everted).
Organ very short (
5.7 mm
long) and stout (
4.9 mm
wide); extending upto 2 subcaudal scales; unilobed, lobe head wide (
5.3 mm
), pedicel not quite narrow (pedicel length
3.4 mm
), barely visible through the flounces; organ beset with large spiny flounces fairly densely throughout; length of largest spine
0.9 mm
; spines largely erect and short while a few including some on proximal, distal and dorsal part of the organ curved and elongate; in asulcate view, spiny flounces cover the entire length of the pedicel, no plain smooth patch visible; in sulcate, view a mild patch of plain aspinose part visible, sulcus spermaticus mildly visible, like a groove, centripetal, turning to the right (
Fig. 11
d–f).
Maxillary arch dentition (dissected from BNHS 2015).
Arched with a dip towards diastema; 13 teeth perpendicular to maxilla, curving inwards; prediastemal teeth 7, postdiastemal teeth 6, observable gradual tooth size increase in prediastemal tooth set with the largest teeth precursing diastema; diastema smaller, about 4 tooth-sockets wide, suffixed with a set of 4 uniform, smaller teeth followed by the last grooved pair of large teeth (
Fig.
6g
).
Distribution and habitat.
Ahaetulla sahyadrensis
nom. nov.
is herein recorded from the Central Western Ghats. However, the actual distribution range will stretch across the Western Ghats (
McCann 1940
;
Das 2002
;
Whitaker & Captain 2004
), possibly distributed in moist deciduous and evergreen forests from just above sea level till 1500 msl (metres above sea level). They are primarily arboreal, occasionally terrestrial and found in the vicinity of perennial streams.