Dendrelaphis sinharajensis Wickramasinghe, 2016, sp. nov.
Creators: name: Mendis Wickramasinghe, L. J.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Colubridae
Dendrelaphis
Dendrelaphis sinharajensis

description: Dendrelaphis sinharajensis sp. nov.
Holotype. NMSL 2016.06.0 1 NH, adult female, SVL 672 mm, TL 323 mm, Mideripitiya, Sinharaja Forest, Deniyaya, Matara District, Southern Province (N 06º 21' 24.72’’, E 080º 29' 21.63’’), 285 m (Figure 1). Coll. L. J. M. Wickramasinghe.
Diagnosis. I assign the new species tentatively to the genus Dendrelaphis because it possesses the following characteristics: slender body; rounded pupil; enlarged vertebral scales; head distinct from body; diurnal; predominantly arboreal. Within the genus, Dendrelaphis sinharajensis has a unique colour pattern of prominent cross bars in black and white and a red neck; black bars are paired, and create the margins of the white cross bars from neck to tail; vertebral stripe, postocular stripe, and ventrolateral stripe absent; prominent white patch on lateral head over eye region and neck, upper margin outlined by a black zigzag line; parietal stripe present; throat white with black blotches; venter off-white with irregular black spots all over. It further differs from all other species of this genus in the combination of the red neck and the conspicuous red/white cross bars. In addition to its colouration, the species can be readily distinguished from its congeners by the following combination of characteristics: loreal scales absent; prefrontals large, contacting 2nd and 3rd supralabials; postoculars three, central scale smallest; anterior temporal large, contacts all three postaculars; posterior temporals three, central one largest, larger than anterior temporal, dorsally contacts parietal and ventrally contacts 8th supralabial; dorsal scale rows 13 at midbody, a small apical pit on each costal scale; ventral scales 174; subcaudal scales 139; vertebral scales slightly longer than the first costal row.
Description of holotype. Body slender, SVL 672 mm; tail long, (TL/SVL 48.1%; TL/ToL: 32.5%); head long (HL/SVL 3.36%), distinct from the neck. Eye large, ED/HL 22.6%. Pupil round. Nostril small, (ND/ED 5.88%); snout moderate (NE/HL 20.8%) (Figure 2 A). The dark purplish tongue is protruded. Internasals two; prefrontals large (Figure 2 B), contacting nasal, 2nd and 3rd supralabials and preocular; postoculars three, central one smallest; supraocular single; loreal absent. Preocular single, not reaching dorsal surface of head; postoculars three; temporals 1:3 (anterior temporal large, contacts all three postoculars; posterior temporals three, central one largest, larger than anterior temporal, dorsally contacts parietal and ventrally contacts 8th supralabial); supralabials eight, 4th and 5th contacting eye (Figure 2 A); infralabials 11, first pair in medial contact at the mental groove; 1st to 5th contacting anterior chin shield; 5th and 6th contacting posterior chinshield, 6th the largest; first sublabial short, touches infralabials 6 and 7 (L), or infralabials 6, 7 and 8 (R) (Figure 2 C); dorsals 13:13:09; dorsal scales oblique (Figure 3 A), smooth and with a single apical pit; vertebral scales enlarged (Figure 3 B), slightly larger or equal to first row of dorsals, hexagonal in shape and with clearly concave posterior margin; ventrals 174 (+2 preventrals), laterally sharply keeled with a notch on each side; anal shield divided; subcaudals 138 divided, plus one terminal scale.
Measurements (to the nearest 0.1 mm): CL 4.1; ED 5.1; HD 7.3; HL 22.6; HW 9.4; IN 4.9; IO 10.6; NE 4.7; ND 0.3; SE 7.5; SS 19.3; SN 2.6.
Colour in alcohol (holotype). Head dorsum brown, with a prominent black line between parietals. A prominent white patch on lateral head over eye region and neck, with upper margin outlined by a black zigzag line. Background body colour brown, with prominent paired narrow black cross bands (about one costal scale wide) throughout body, with a light brown band (1–2 costal scales wide) between them. Venter off-white with irregular black spots all over.
Colour in life (based on photographed unpreserved specimen). Kudawa, Sinharaja Forest, Ratnapura District, Sabaragamuwa Province (N 06º 26' 52.07’’, E 080º 24'58.33’’). Head dorsum brown, with a prominent black line between parietals (Figure 4). A prominent white patch on lateral head surrounding eye region and neck, with its upper margin outlined by a black zigzag line (Figure 5). Tongue dark purple. Dorsum background red anteriorly (Figure 6) and earthy brown posteriorly, with prominent cross bars in black and white. The black bars are paired, and create the margins of the white cross bars from neck to tail (Figure 7). Venter off-white with irregular black spots all over.
Etymology. The species epithet sinharajensis is derived from “ Sinharaja ”, referring to the forest where the species was discovered. The specific name is an adjective from the geographical name.
Suggested vernacular names. The vernacular names recommended for the species are Sinharaja haldanda, Sinharaja komberi muken, and Sinharaja tree snake in the languages Sinhala (native), Tamil, and English respectively.
Comparison. The new species can clearly be distinguished from all known congeners of the genus Dendrelaphis by the presence of a large central posterior temporal scale, and from all except D. oliveri (Taylor, 1950) by the absence of a loreal scale; prefrontals contacting 2nd and 3rd supralabials. Dendrelaphis sinharajensis sp. nov. additionally differs from D. oliveri by its prefrontals contacting the 2nd and 3rd supralabials only (vs 2nd, 3rd and 4th), three postoculars (vs two), temporals 1:3 (vs 1:1) (Figure 8 A); parietal stripe present (vs absent) (Figure 8 B), and throat white with black blotches (vs blotching absent) (Figure 8 C), ventrolateral stripe absent (vs ventrolateral stripe present) (Figure 9 & 10). Although the new species is sympatric with D. caudolineolatus, and can be confused due to; similar dorsal scale rows at midbody 13, and fairly similar body colouration (Figure 11), D. sinharajensis sp. nov. can readily be distinguished from D. caudolineolatus, by the absence of a loreal scale (vs present), prefrontals contacting 2nd and 3rd supralabials (vs prefrontals and supralabials separated by a loreal scale), three postoculars (vs two) (Figure 12 A); temporals 1:3 (vs 1:1 or 1:2) (Figure 12 A & 13B); posteriormost point of frontal and posteriormost points of supraoculars not aligning in a straight line (vs aligning) (Figure 12 B), infralabials 1st to 5th contacting anterior chin shield (vs 1st to 4th), 5th and 6th contacting posterior chinshield (vs 4th and 5th), 6th the largest (vs 5th) (Figure 12 C), combination of the red neck and the conspicuous red/white cross bars (vs oblique black stripes on anterior bronze body, that meets mid dorsally forming a ‘V’ shape) (Figure 13 A), postocular stripe absent (vs present) (Figure 13 B), parietal stripe present (vs absent) (Figure 13 C), throat with black blotches (vs blotching absent) (Figure 13 D).
Dendrelaphis sinharajensis sp. nov. can clearly be distinguished from all other Sri Lankan congeners in colour pattern, since this is the only species in the genus characterized by conspicuous red/white cross bars around its body, where the black bands appear to be paired, and with a distinct white patch on lateral head covering eye region and neck, with its upper margin outlined by a black zigzag line on all individuals.
Habitat, ecology and conservation. Dendrelaphis sinharajensis sp. nov. was first discovered from Sinharaja World Heritage Site, located in the lowland wet zone of the island. Four additional individuals of this species have been sighted, from Horagasmandiya, Palenda, Kalutara District, Western Province (N 06º 33' 51.11’’, E 080º 15' 44.23’’), Kukuleganga, Ratnapura District, Sabaragamuwa Province (N 06º 34' 27.84’’, E 080º 19' 44.28’’), Athwelthota, Ratnapura District, Sabaragamuwa Province (N 06º 32' 38.39’’, E 080º 16' 53.77’’), and Rusigala- Mannawaththa, Ratnapura District, Sabaragamuwa Province (N 06º 30' 21.89’’, E 080º 19' 00.34’’), all to the north-west of the type locality, but still in the vicinity of the Sinharaja WHS. All four individuals were identified on the basis of both its unique colour pattern, and the presence of the diagnostic features specially the absence of a loreal scale. The known localities for the species cover an area of 57.96 km 2, of which 49.25 km 2 is dense forest, 6.33 km 2 is moderately dense forest, 0.91 km 2 is pine plantation, 0.37 km 2 is scrub-land, and 1.10 km 2 is sparse open forest and tea plantation (Figure 1).
The species is rarely sighted, and may be rare. The first specimen collected was a road kill. The photographed individual was found in the canopy at around 15 m above ground level. The rarity of sightings may be due to a highly arboreal nature in the higher canopy of the lowland wet zone. Probable threats to this species are habitat loss and forest fragmentation through deforestation. The species is sympatric with D. caudolineolatus and D. schokari.
Remarks. Absence of loreal scales sometimes (but rarely) occurs as an anomaly in Dendrelaphis. However the lack of a loreal scale was consistently observed in all live individuals sighted as well as in the photographed live individual, of the new species. This suggests that it is an important characteristic feature of the species and not an anomaly of the holotype of D. sinharajensis sp. nov..
The holotype and only known specimen of Dendrelaphis oliveri (Taylor, 1950) is deposited in the Field Museum of Natural History, Chicago. Although Dendrelaphis oliveri (Taylor, 1950) lacks a loreal scale (Figure 8 A), similar to the new species, they are geographically well separated with the type locality of D. oliveri, 12 miles north of Trincomalee, Eastern Province, in the dry zone of the island. In addition to the characters mentioned above that distinguish it from D. sinharajensis, the holotype of D. oliveri has a pale ventrolateral line bordered by black lines (Figure 9 & 10), a character absent in all other known species found in Sri Lanka. Taylor’s handwritten specimen catalog (pg. 115, EHT-HMN No: 30388) notes that the original field tag on the holotype was missing (Figure 14), but has clearly mentioned in the same catalog as, “Certainly 12 km N Trincomalee Ceylon E H T Coll”. The species has not been recorded since Taylor’s 1950 description, and our studies at this locality and in its vicinity over a period of two years have also failed to locate the species. Hence, it is possible that the holotype of D. oliveri was not collected at the stated type locality, and may not even be from Sri Lanka. Further studies of this enigmatic species are needed.
description: Published as part of Mendis Wickramasinghe, L. J., 2016, A new canopy-dwelling species of Dendrelaphis (Serpentes: Colubridae) from Sinharaja, World Heritage Site, Sri Lanka, pp. 504-518 in Zootaxa 4162 (3) on pages 506-513, DOI: 10.11646/zootaxa.4162.3.5, http://zenodo.org/record/264526