Hebius lacrima PURKAYASTHA & DAVID, 2019
Can you confirm these amateur observations of Hebius lacrima?
|Higher Taxa||Colubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||Crying Keelback|
|Synonym||Hebius lacrima PURKAYASTHA & DAVID 2019|
|Distribution||India (Arunachal Pradesh)|
Type locality: Basar (27.980559°N, 94.688496°E), West Siang District, State of Arunachal Pradesh, India, at ca. 600 metres elevation
|Types||Holotype: ZSI 610 (given as VR/ERS/ZSI), adult male. Collected by a villager, preserved in concentrated formalin and subsequently given to Jayaditya Purkayastha, 7 August 2010.|
|Diagnosis||Diagnosis. A species of the genus Hebius characterized by combination of the following characters: (1) body elongate; (2) tail amounting for 30.1 % of the total length; (3) 24 gradually enlarged maxillary teeth, followed, with a diastema, by 3 distinctly enlarged posterior teeth; (4) nostrils lateral; (5) internasals broad anteriorly; (6) 2 preoculars; (7) 1 anterior temporal, (8) 19–19–17 dorsal scale rows, distinctly keeled except scales of the 1st rows, smooth but distinctly enlarged; (9) 147 ventrals, not keeled (+ 2 preventrals); (10) anal divided; (11) 89 subcaudals; (12) a white stripe extending on the middle of supralabials from the edge of rostral and 1st SL to the anterior half of the 6th SL just below the eye; a second stripe, slightly higher on the labials and temporal regions than the first one, extends from the 7th SL to the 9th SL then beyond the angle of jaw to the nape, producing a short V-like chevron; (13) a dark area on the posterior half of 6th SL, separating the two white stripes; (14) dorsum dark greyish-brown variegated with blackish-brown blotches, without stripe or aligned dorsolateral dots; (15) venter ivory with a large, elongate blotch parallel to the body axis near the tips of each ventral, forming a discontinuous ventrolateral stripe.|
Comparisons with species of the genus Hebius. Hebius lacrima spec. nov. can be differentiated from all other species of the genus Hebius by the combination of (1) a distinctive broad, white, interrupted stripe on the supralabials, (2) each side with three rows of irregular dark blotches, not vertically aligned, (3) a short dorsolateral row made of a total of six cream, elongate spots on its anterior part, and (4) the first dorsal scale row being entirely smooth. The interrupted pale head stripe differentiates Hebius lacrima spec. nov. from all other natricid species of the Indo-Himalayan and Indochinese Region.
Hebius lacrima spec. nov. is further distinguished from Hebius annamensis (Bourret), Hebius atemporalis (Bourret), Hebius chapaensis (Bourret), Hebius groundwateri (Smith), Hebius sauteri (Boulenger) (including the subspecies H. s. bourreti and H. s. maximus), Hebius venningi (Wall) and Hebius taronensis (Smith), as well as three species present in Borneo, i.e., Hebius arquus (David & Vogel), Hebius frenatus (Dunn) and Hebius sarawacensis (Günther), by having 19 DSR vs. 17 rows in these species or sometimes 15 in H. annamensis.
Furthermore, Hebius venningi has a venter pale mesially on the anterior part of the body, clouded with darker hues of brown on the outer parts of ventrals, entirely clouded posteriorly (entirely creamish-white in Hebius lacrima spec. nov.) and a distinct dorsal pattern composed of large elongate blotches (faint series of three dark blotches in H. lacrima spec. nov.). Hebius atemporalis lacks temporal scales (present in H. lacrima spec. nov.).
Among other species of Hebius with 19 dorsal scale rows, Hebius bitaeniatus (Wall), H. parallelus (Boulenger) and H. clerki (Wall) possess distinct continuous, more or less bright dorsolateral stripes (absent in Hebius lacrima spec. nov.). A description of Hebius bitaeniatus can be found in David et al. (2005) whereas the complex of Hebius parallelus and H. clerki was reviewed in David et al. (2015). Furthermore, H. clerki has more ventrals, 158–173 (vs. 147) and scales of the 1st DSR are strongly keeled (vs. smooth). H. parallelus has more ventrals, 160–173, and fewer subcaudals, 63–77 (vs. 147 and 89 respectively). H. bitaeniatus also differs in having more ventrals, 153–177 (vs. 147) and scales of the 1st DSR are strongly keeled (vs. smooth). Lastly, among these conspicuously striped species, H. octolineatus (Boulenger) has a distinctly shorter tail, with ratio TaL/TL ranging between 0.208–0.258 (vs. 0.301).
Among Chinese species of Hebius (see Zhao et al. 1998; Zhao 2006), Hebius metusia (Inger, Zhao, Shaffer & Wu) differs by having a dorsal pattern both blotched and striped (vs. blotched), more ventrals, 159–164 (vs. 147), and a different pattern of the supralabials. Hebius optatus (Hu & Zhao) and Hebius andreae (Ziegler & Le) possess pale, transversal, narrow or wide dorsal crossbars (vs. on each side three rows of irregular, faint dark blotches, not vertically aligned). Furthermore, H. optatus has more ventrals (156–169 vs. 147) and supralabials dark with two white streaks running from the lower edge of eye. Lastly, Hebius lacrima spec. nov. differs from Hebius popei (Schmidt) by a slightly higher number of ventrals, 131–142 (vs. 147), a different dorsal pattern made of pale crossbars on dorsolateral stripes and a large, white nuchal blotch (vs. dorsolateral stripes absent and a V-like chevron present).
Several Indo-Himalayan and Indochinese species of the genus Hebius with 19 DSR have the venter partly or entirely dark brown or blackish-brown. This group includes Hebius modestus (Günther), Hebius deschauenseei (Taylor) and a species under description (David et al. in prep.). H. modestus differs from Hebius lacrima spec. nov. in having a venter pale in its centre but more or less extensively dark on its sides (vs. entirely creamish-white with lateral dark dots), supralabials creamish-yellow, yellowish-brown or pale brown, usually speckled with dark brown and all edged with dark brown or blackish-brown (vs. a broad, entirely white central area), the lack of postocular stripe (vs. present), usually a dorsolateral stripe (vs. absent) and more subcaudals, 104–122 vs. 89. Hebius deschauenseei differs from Hebius lacrima spec. nov. by the pattern of its venter, covered with three rows of large dark blotches (vs. creamish-white), a dorsolateral stripe (vs. absent), supralabials strongly powdered with olive- brown, greyish-brown or pale brown and edged with dark brown, and more subcaudals, 115–141 SC (vs. 89). Lastly, Hebius sp., currently under description, differs by its venter entirely dark (vs. creamish-white), dark supralabials, a dorsolateral series of large, orange or rusty-red blotches, a high number of ventrals, at least 159 (vs. 147), and very strongly keeled scales around the base of the tail (vs. smooth). Tentatively included in this group, Hebius xenura (Wall) differs from Hebius lacrima spec. nov. by its single subcaudals (vs. divided).
Hebius lacrima spec. nov. shares some characters with species of the “Hebius khasiensis species-group” as defined in David et al. (2013; as the “Amphiesma khasiense species-group”). This artificial group contains seven species: H. khasiensis (Boulenger), H. atemporalis (Bourret) (with 17 DSR, see above), H. boulengeri (Gressitt), H. inas (Laidlaw), H. johannis (Boulenger), H. kerinciensis (David & Das) and H. leucomystax (David, Bain, Nguyen, Orlov, Vogel, Vu & Ziegler). Both H. khasiensis and H. inas differs from Hebius lacrima spec. nov. by the pattern of their supralabials, composed of distinct, pale blotches in H. khasiensis and H. inas, at least on the posterior supralabials (vs. two consecutive white stripes), scales of the 1st DSR distinctly keeled, at least posteriorly, in H. inas and H. khasiensis (vs. smooth). Furthermore, the pattern of the neck in H. khasiensis is usually made of isolated rounded blotches, sometimes partly connected by a narrow pale line (vs. a conspicuous V- like chevron on the neck).
Although Hebius boulengeri (Gressitt) also possesses a distinct white streak on the supralabials and neck, it is narrow (vs. broad) and extends from the posterior lower margin of the eye on posterior supralabials up to the nape, without forming a strong chevron (vs. first labial stripe, before the black “tear”, extending from the snout). H. boulengeri further differs from H. lacrima spec. nov. by the presence of distinct dorsolateral stripes marked with irregular spots (vs. absent).
Regarding other species of the H. khasiensis complex, Hebius johannis is further differentiated from H. lacrima spec. nov. by the number of supralabials, 7–8 (vs. 9–10), a higher number of ventrals, 165–175 according to Zhao et al. (1998) (vs. 147). H. craspedogaster further differs from H. lacrima spec. nov. by the number of anterior temporals, usually 2 or 3 (vs. 1) (Pope 1935; Zhao et al. 1998).
The sole other species of Hebius with a broad, white stripe on the supralabials is Hebius leucomystax (see David et al. 2007). This latter species differs from H. lacrima spec. nov. by having an uninterrupted white stripe on the supralabials (vs. interrupted on the 7th supralabial), and lower numbers of ventral scales, 154–166 (vs. 147) and of subcaudals 94–103 (vs. 89).
Lastly, in the Indo-Himalayan Region, Hebius pealii (Sclater) differs from H. lacrima spec. nov. by having a single cloacal plate (vs. divided), two anterior temporals (vs. 1), 19–21 maxillary teeth (vs. 26 or 27), and a different dorsal pattern.
|Comment||Habitat: The single known specimen was obtained from a rice field alongside a hill slope in the outskirt of the city of Basar, so in a heavily disturbed area.|
Genus: In the absence of molecular data, the authors could not ascertain the generic relationships of this new species which was tentatively referred to the wide-ranging genus Hebius as defined by Guo et al. (2014) on the basis of its elongate body, of the pattern of the venter and of its dentition on the upper maxilla i.e., three enlarged teeth separated by a short diastema from anterior maxillary teeth. Such a dentition is also found in species such as Hebius clerki and H. parallelus (see David et al. 2015).
|Etymology||The species nomen derives from the Latin noun lacrima (-ae), meaning “a tear”, a reference to the dark area under the eye looking like a black tear which interrupts the white supralabial stripe. This species nomen is a noun in apposition and not an adjective.|
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