Ahaetulla nasuta ( Lacépède, 1789 )

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 : 12-13

publication ID	https://doi.org/ 10.11646/zootaxa.4874.1.1
publication LSID	lsid:zoobank.org:pub:8FF98990-0E47-4BB7-82BB-098F86771271
DOI	https://doi.org/10.5281/zenodo.4567185
persistent identifier	https://treatment.plazi.org/id/353C523C-140C-2636-FF50-96F0FDE8F8D7
treatment provided by	Plazi
scientific name	Ahaetulla nasuta ( Lacépède, 1789 )
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Ahaetulla nasuta ( Lacépède, 1789)

Coluber nasutus Lacépède, 1789

Coluber nasutus (not of Shaw, 1802)

Ahaetulla mycterizans (non Coluber mycterizans Linnaeus, 1758 ) Link, 1807 —nomen praeoccupatum

Drijinus nasutus — Bleeker, 1856 (nomen emendatum)—after Wallach et al. (2014)

Dryophis mycterizans rhodonotus Wall, 1921

Dryophis mycterizans View in CoL (not of Linnaeus, 1758)— Wall, 1921: 291

Comments. The type locality of Coluber nasutus was originally mentioned as “à Malabar, à Ceylan, à Pondichery, au Bengale, à Java, aux îles Philippines et aux Mariannes”, but restricted to Ceylon by Smith (1943) (fide Wallach et al. 2014). But the only Asian country with an Ahaetulla population mentioned by Lacépède (1789) in his text dealing with this taxon as ‘La Nasique’ in Ceylon, barring New Guinea and Carolina ( USA). The type locality of the synonym Dryophis mycterizans rhodonotus is also in Sri Lanka (see Wall 1921; David & Dubois 2005) ( Fig. 8 View FIGURE 8 & 9 View FIGURE 9 ).

Coluber nasuta Lacépède, 1789 [as Ahaetulla mycterizans Link, 1807 ] is the type species of the genus Ahaetulla Link, 1807 by subsequent designation ( Meise and Hennig 1932) (see Savage 1952; Savage & Oliver 1956).

Link’s (1807) concept of A. mycterizans was different from that of Linnaeus’ (1758) Coluber mycterizans , a predominantly Malayan species. Linnaeus’ (1758) name being a senior nomen takes precedence over Link’s (1807) junior nomen. Thus Coluber mycterizans Linnaeus, 1758 becomes a senior secondary homonym of A. mycterizans Link, 1807 . Therefore, as these two nominate taxa are now considered congeneric ( Wallach et al. 2014; this work), in accordance with Art. 59.1 and Art. 60.2 of ICZN, 1999 Ahaetulla nasuta ( Lacépède, 1789) is deemed to be the subsequent available nomen for this population. Historically, Shaw (1802) under his accounts of Coluber ‘nasutus’ remarked that, according to Seba, the type locality of the taxon ‘Serpens viridis’ is Java. Therefore, Seba’s taxon from Java refers to Ahaetulla mycterizans ( Linnaeus, 1758) , an Indomalayan species.

The type of the subjective junior synonym Dryophis mycterizans rhodonotus Wall, 1921 was presented by Mr. Drummond-Hay, and Wall examined it only in preservative and still named it as new, relying on the presenter’s words that it was of a reddish colour in life.

Referred material. BNHS1987; adult female; Loc. Colombo, “ Ceylon ” (Present day Sri Lanka); Coll. J.H. Stone; 1912.

Type locality. ‘ Ceylon’ currently Sri Lanka .

Etymology. Latin, nasuta = ‘of the nose’ an adjective alluding to its elongate snout.

Diagnosis.

1. Ahaetulla nasuta (L2) is phylogenetically basal to the clade comprising 4 other new lineages (L3, L4, L5 & L6) from the Western Ghats and separated from the Indian lowland A. oxyrhyncha clade (L1).

2. The Western Ghats cluster of Ahaetulla are genetically divergent from A. nasuta—Ahaetulla isabellina comb. nov. (L5) (7.5 % & 9.9 %), A. farnsworthi sp. nov. (L4) (7.9 % & 9.7 %), A. malabarica sp. nov. (L6) (7.4 % & 10.3 %) and A. borealis sp. nov. (L3) (8.9 % & 10.8 %) at Cytb and ND4 genes, respec-tively.

3. This is a species of Ahaetulla with a rostral appendage (vs. absent in A. dispar , A. perroteti , A. travancorica sp. nov.; vs. long multi-scaled rostral appendage in A. pulverulenta , A. sahyadrensis nom. nov. & A. ano-mala), possessing a white ventrolateral stripe (vs. absent in A. pulverulenta , A. sahyadrensis nom. nov.); lacking a loreal scale (vs. present in A. dispar and A. travancorica sp. nov.); 6 pre-diastemal and 6 post-diastemal maxillary teeth (vs. 7 and 9 in A. isabellina comb. nov., vs. 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.); having usually green body colouration (vs. usually grey-brown in A. sahyadrensis nom. nov.; adult females usually brownish in A. anomala , A. dispar and A. perroteti ) ( Fig. 6e View FIGURE 6 & 7 View FIGURE 7 , Table 2 View TABLE 2 ).

4. Ahaetulla nasuta is endemic to the central and southwestern wet zone of Sri Lanka, which is the type local-ity ( Ceylon), separated from India by the Palk Strait. Within Sri Lanka, the presence of multiple species is possible, given the intrinsic heterogeneity of this island (also see Deepak et al. 2019). We herein revise and restrict the nomen to the wet hilly zone of Sri Lanka.

Description of Referred material. Adult female of total length 1055 mm; broken in its current state of preservation; very slender, partially laterally compressed body with snout to vent length 651 mm; tail length 404 mm; relative tail length 0.63; ventrals 182 notched with keels; subcaudals 158 (with a part of the tail missing), divided; cloacal scale divided; relatively long and slender tail; dorsal scale rows in 14(forebody)-15(midbody)-13(hindbody) rows of smooth, obliquely disposed scales; head very distinct from neck with head length 27.2 mm; transversely oval eyes with horizontal pupil; with a horizontal diameter of 6.3 mm and vertical diameter of 4.1 mm; distance from nostril to eye 8.4 mm; distance from snout tip to eye 11.6 mm; supralabials 9 (both left and right) with the 5 th supralabial being the largest, in contact with the eye; 4 th supralabial divided; infralabials 7 (both left and right); 1 st, 2 nd and 3 rd infralabials in contact with anterior genials; 3 rd and 4 th infralabials in contact with the posterior genials; mental scale wedged in between 1st pair of infralabials; nasal scale 1 (both left and right), entire; loreals absent; pre-subocular 2 (both left and right); pre-ocular 1 (both left and right); post-oculars 2; sub-oculars absent; temporals 2+2+2 (both left and right); prefrontal scale in contact with the pre-oculars; preventral 1; rostral appendage with 2 scales.

Maxillary arch dentition (dissected from BNHS1987). Arched with a dip in the arch towards the diastema; 12 teeth perpendicular to maxilla, curving inwards; prediastemal teeth 6; postdiastemal teeth 6, observable gradual tooth size increase in prediastemal tooth set with the largest teeth precursing the last tooth behind the diastema; diastema about 3 tooth-sockets wide; suffixed with a set of 4 smaller teeth followed by the last grooved pair of large teeth ( Fig. 6e View FIGURE 6 ).

Colour in preservative. Body with a non-uniform dark bluish violet colour; rostral and infralabials dark bluish violet with white blotches and speckles; a white temporal streak starting from the 6 th supralabial scale that runs along the side with the row of dorsal scales that is in contact with the ventrals, white ventral stripe along the ventrals, close to the centre of the ventrals with a gap of 1.5mm between the stripes; slight discolouration in the supralabials; yellow clouded with white eyes.

Distribution and habitat. Ahaetulla nasuta is endemic to Sri Lanka, being found in the central and southwestern parts, in the wet zone (also see Das & de Silva 2005; Somaweera 2006) ( Fig. 4 View FIGURE 4 ). However, further sampling is needed to resolve the systematics of the Sri Lankan Ahaetulla including the montane forms (see sample in Pyron et al. 2013).

The status of extralimital populations of the Ahaetulla nasuta group is beyond the scope of the present study and will be addressed elsewhere.