Ahaetulla pulverulenta ( Duméril, Bibron & Duméril, 1854 )

Mallik, Ashok Kumar, Srikanthan, Achyuthan N., Pal, Saunak P., D’Souza, Princia Margaret, Shanker, Kartik & Ganesh, Sumaithangi Rajagopalan, 2020, 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, Zootaxa 4874 (1), pp. 1-62 : 22-24

Ahaetulla pulverulenta ( Duméril, Bibron & Duméril, 1854)

Dryinus pulverulentus Duméril, Bibron & Duméril, 1854

Dryinus fuscus Duméril, Bibron & Duméril, 1854 — Dumeril et al. 1854 part

Dryophis pulverulentus Jan, 1863

Passerita purpurascens Günther, 1864

Ahaetulla pulverulenta xanthiscuta Deraniyagala, 1955

Dryophis pulverulentus — Wall 1921; Smith 1943 part;

Ahaetulla pulverulenta — Das & de Silva 2005; Wallach et al. 2014 part

Comments: David & Dubois (2005) elaborated on the taxonomic and nomenclatural history of this species, besides redescribing its holotype. As currently understood, this species has four subjective junior synonyms. One of them Dryophis pulverulentus Jan, 1863 is, in addition, also a secondary homonym of Dryinus pulverulentus Duméril, Bibron & Duméril, 1854 (see David & Dubois, 2005).

Type Material and Type Locality. Holotype (by monotypy), MNHN 7565 coll. Louis Theodore Leschenault, collected from “Ceylan”, present day Sri Lanka.

Etymology. Latin, named after its ‘ashy’ or ‘dusty’ greyish brown colouration.

Material examined. 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.

Diagnosis.

1. Phylogenetically, Ahaetulla pulverulenta (L8) is sister to the clade comprising A. sahyadrensis nom. nov. (L7), A. oxyrhyncha comb. nov. (L1) and A. anomala .

2. A. pulverulenta shows a moderate level (4.52 % in Cytb and 1.7 % in 16S) of genetic divergence from A. sahyadrensis nom. nov. of the Western Ghats (see below).

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 Peninsular India Ahaetulla spp., except A. anomala and A. sahyadrensis nom. nov.); lacking white or yellow ventrolateral stripe (vs. present in all regional congeners except A. sahyadrensis nom. nov.); 8 pre-diastemal and 7 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. & 7 and 6 in A. sahyadrensis nom. nov. from India, dissected from BNHS 2010); differs from A. sahyadrensis nom. nov. of India in ventral scale counts 179–193 [182–186 in BNHS specimens] (vs. 182–203 [186–202 in our study] in A. sahyadrensis nom. nov.) and subcaudal scale counts 151–178 [158–159 in BNHS specimens] (vs. 169–208 [175–208 in our study] in A. sahyadrensis nom. nov.); lower posterior dorsal scale rows count 10–11 (vs. 12–13 in A. sahyadrensis nom. nov.) ( Fig. 11 & 12 , Table 2 ).

4. Ahaetulla pulverulenta is an insular endemic species, restricted to the island of Sri Lanka and separated by geographic barriers—the Palk Strait and the Indian dry zone—from A. sahyadrensis nom. nov. of the Western Ghats.

Description and Variation. Adult specimens very slender, partially laterally compressed body with a maximum snout to vent length 827 mm; tail length (253 mm for specimen of SVL 454 mm; other specimens with broken or damaged tails); ventrals 182–186 notched with keels; subcaudals 158–161 divided; 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, supralabials 8 (both left and right) with 5 th & 6 th supralabial being the largest, 5 th in contact with the eye; 4 th supralabial divided; infralabials 7 (both left and right);1 st, 2 nd, 3 rd and 4 th infralabials in contact with the anterior genials; 4 th, 5 th and 6 th infralabials in contact with the posterior genials; mental scale wedged in between 1st pair of infralabials; nasal 1 (both left and right); loreals absent; pre-subocular 1 (both left and right); pre-ocular 1 (both left and right); post-oculars 2; sub-oculars absent; temporal 2+3 (both left and right); prefrontal scale in contact with pre-oculars; preventrals 2; rostral appendage comprised of numerous smaller scales.

Colour in preservative. Specimens with light brown to grey dorsum with speckles of dark brown in the light coloured scales; anterior part of the body with hints of black to dark brown cross oblique bands facing backwards; venter light brown to grey with dark brown speckles, uniform throughout the venter, extending till the tip of the tail; head with dark brown markings on the dorsum, prominent pre-ocular and post-ocular stripe in dark brown, dotted with light grey; pre-ocular stripe extends till the nape and abruptly ends.

Maxillary arch dentition (dissected from BNHS 2010). Arched with a dip towards diastema; 15 teeth perpendicular to maxilla, curving inwards; prediastemal teeth 8, postdiastemal teeth 7, observable gradual tooth size increase in prediastemal tooth set with the largest teeth precursing diastema; diastema smaller, about 3 tooth-sockets wide, suffixed with a set of 5 uniform, smaller teeth followed by the last grooved pair of large teeth ( Fig. 6 ).

Distribution and habitat. Ahaetulla pulverulenta is endemic to Sri Lanka, where it occurs almost throughout the island except the high (> 1200 m AMSL) elevations (see Wall 1921; Das & de Silva 2005).

Figures

FIGURE 6. Ahaetulla lineages in Peninsular India and Sri Lanka showing side-by-side comparison of their superficial head morphology and maxillary dentition. (From the top) (a) Ahaetulla farnsworthi sp. nov. (b) A. isabellina comb. nov. (c) A. malabarica sp. nov. (d) A. borealis sp. nov. (e) A. nasuta (f) A. oxyrhyncha comb. nov. (g) A. sahyadrensis nom. nov. (h) A. travancorica sp. nov. (i) A. dispar & A. travancorica sp. nov. (j) A. perroteti (1) Ahaetulla farnsworthi sp. nov. (2) A. isabellina comb. nov. (3) A. malabarica sp. nov. (4) A. borealis sp. nov. (5) A. nasuta (6) A. oxyrhyncha comb. nov. (7) A. pulverulenta (8) A. sahyadrensis nom. nov. (9) A. dispar (10) A. travancorica sp. nov. (11) A. perroteti.

FIGURE 11. Images of Ahaetulla sahyadrensis nom. nov. Images of BNHS2015. (a) Head dorsal. (b) Head lateral. (c) Section of body and ventrals. (d–f) Everted Hemipenis. (g) Full specimen. Images of live, uncollected individuals, (h) Near Jog falls, Karnataka, (i) from Agumbe, (j) Kudhremukh, (k) from Agumbe (Images a & b; d, e & f to scale, other images not to scale).

FIGURE 12. Images of Ahaetulla pulverulenta, Sri Lanka. (a) Head dorsal, (b) Head lateral, (c) Whole animal (images not to scale).