Pareas sp.

Vogel, Gernot, Nguyen, Tan Van, Zaw, Than & Poyarkov, Nikolay A., 2021, A new species of the Pareas monticola complex (Squamata: Serpentes: Pareidae) from Chin Mountains with additions to the Pareas fauna of Myanmar, Journal of Natural History 54 (39 - 40), pp. 2577-2612 : 2597-2603

Pareas sp.

( Figures 4 (c) and 7; Tables 1 and 6)

Chresonymy

Pareas monticola – (in part) Vogel 2015: 07.

Material examined. CAS 224415, adult female collected on 1 April 2002, by K.S. Lwin, M. Kyaw, A. Sin and A. Di, from montane evergreen forest in Lon Nut Village, Hkakabo Razi

(Continued) NP, Nagmung Township , Putao District, Kachin State, northern Myanmar (27.768286°N, 97.818992°E; at an elevation of 1010 m asl) .

Diagnosis. Pareas sp. from Hkakabo Razi NP differs from all other members of the genus Pareas by the combination of the following morphological characters: slender yellow-brown medium-sized snake (total length 477 mm); 2 anterior temporals; frontal scale subhexagonal with the lateral sides converging posteriorly; anterior pair of chin shields longer than broad; loreal contacting the eye; prefrontal contacting the eye; preoculars present; 1 subocular, 1 postocular; temporals 2 + 3; a single median row of slightly enlarged vertebral scales; 7 infralabial scales, 2nd–5th supralabials touching the subocular; 5 slightly keeled dorsal scale rows at midbody; 182 ventrals without lateral keels; 71 subcaudals, all divided; 60 slightly billowing indistinct vertical dark bars on the trunk; head laterally and ventrally with dense, dark dusting lacking larger dark markings and postocular stripes, vertical dark blotch at nape.

Morphological chracteristics. Body slender and notably flattened laterally; head comparatively large, narrowly elongated, clearly distinct from thin neck (head more than 2 times wider than neck width near the head basis); snout blunt; eye rather large, pupil vertical and slightly elliptical ( Figure 7 (c,d)).

Body size. SVL 377 mm; TaL 100 mm; TL 477 mm; TaL/TL: 0.210.

Body scalation. Dorsal scales in 15–15–15 rows, 5 scale rows slightly keeled at midbody, without apical pits; vertebral scales slightly enlarged (1 medial row); outermost dorsal scale row not enlarged; ventrals 182 (+1 preventral), lacking lateral keels; subcaudals 71, all divided; cloacal plate single.

Head scalation. Rostral not visible from above; nasal not divided; 2 internasals, much wider than long, narrowing and slightly curving back laterally (in dorsal view), anteriorly in contact with rostral, laterally in contact with nasal and loreal, posteriorly in contact with prefrontal, not contacting preocular; 2 large irregular pentagonal prefrontals, much larger than internasals and with a slightly diagonal suture between them, prefrontal in contact with eye; single frontal shield hexagonal in shape with the lateral sides converging posteriorly, longer than wide, smaller than parietals ( Figure 7 (e)); preoculars present; single subocular crescent shaped, elongated ( Figure 4 (c)); 1 postocular; 1 loreal, narrowly contacting the eye, dorsally contacting preocular, prefrontal, internasal, anteriorly contacting nasal, ventrally contacting 2nd supralabial and subocular ( Figure 4 (c)); 7/7 supralabials, 2nd–5th SL touching subocular, none reaching the eye, 6th by far the largest, elongate; 1/1 supraocular; 2/2 anterior temporals and 3/3 posterior temporals ( Figure 7 (c,d)); 7/7 infralabials, anteriormost in contact with opposite, bordering mental, anterior 5 pairs of infralabials bordering anterior chin shields; 3 pairs of chin shields interlaced, no mental groove under chin and throat; anterior chin shields relatively large, much longer than broad, followed by 2 pairs of chin shields that are much broader than long ( Figure 7 (f)).

Colouration. In preservative, body cream with about 60 dark brown cross bands, which are more distinct in the anterior part of the body, where the bands are formed of completely brown dorsals. In the posterior two-thirds of the body cross bands are less distinct and are formed of dorsals with brownish margins. The cross bands do not reach the ventrals. The head is chocolate brown above with a triangular light-brown blotch at head basis pointing to the parietals ( Figure 7 (e)). Anterior part of the snout heavily speckled with brown. Lateral and ventrals surfaces of the head with dense brown dusting, laterally with a short dark brown streak across the lower temporal and a brown blotch on the last supralabial. Brown dusting on the ventral surfaces of the head continues to the ventrals and the subcaudals. Tail, like body, with numerous hardly countable indistinct dark transverse bands ( Figure 7 (a,b)). Colouration in life unknown.

Comparisons. See Table 6 for information on morphological comparisons of Pareas species. Pareas sp. differs from P. andersonii by loreal contacting eye (vs not in contact); by shorter temporal scales (vs elongated); by enlarged vertebral scales (vs not enlarged); by a higher number of ventrals (182 vs 141–162); by a higher number of subcaudals (71 vs 35–47); and by different colouration of body (cream vs dark grey). Pareas sp. differs from P. atayal by loreal contacting eye (vs not contacting); by a lower number of enlarged vertebral scales (1 vs 3); and by the absence of 2 dark postorbital stripes on the head (vs present). Pareas sp. can be distinguished from P. boulengeri by preoculars present (vs absent); by subocular and postocular not fused into a crescent-shaped scale (vs fused); by 5 keeled dorsal scale rows at midbody (vs all smooth); by enlarged vertebral scales (vs not enlarged); and by a higher number of cross bands on body (64 vs 38–51). Pareas sp. differs from P. carinatus , as well as from P. menglaensis , by frontal scale shape (subhexagonal with the lateral sides converging posteriorly vs hexagonal with lateral sides parallel); by the anterior pair of chin shields longer than broad (vs broader than long); by loreal contacting eye (vs not contacting); by prefrontal contacting eye (vs not contacting); by 2 anterior temporals (vs 3); by a lower number of enlarged vertebral scale rows (1 vs 3); and by the absence of 2 black postorbital stripes (vs presence). Pareas sp. differs from P. chinensis by the presence of preoculars (vs absence); by a slightly higher number of ventrals (182 vs 169–180); and by the absence of 2 black postorbital stripes (vs presence). Pareas sp. differs from P. formosensis by loreal contacting eye (vs not contacting); by a lower number of enlarged vertebral scales (1 vs 3); and by a slightly higher number of ventrals (182 vs 170–180). Pareas sp. is distinct from P.hamptoni by loreal contacting eye (vs not contacting); by a higher number of keeled dorsal scales at midbody (5 vs 0–1); by a lower number of ventrals (182 vs 195); by a lower number of subcaudals (71 vs 96); and by the absence of 2 black postorbital stripes (vs presence). Pareas sp. differs from P. iwasakii by loreal contacting eye (vs not contacting); by a slightly lower number of infralabials (7 vs 9–11); by a slightly lower number of ventrals (182 vs 189–194); by a slightly lower number of subcaudals (71 vs 76–84); and by the absence of 2 black postorbital stripes (vs presence). Pareas sp. differs from P. komaii by loreal contacting eye (vs not contacting); by a lower number of keeled dorsal scales at midbody (5 vs 9–13); by a lower number of enlarged vertebral scales (1 vs 3); and by the absence of 2 black postorbital stripes (vs presence). Pareas sp. differs from P. macularius by loreal contacting eye (vs not contacting); by a slightly lower number of keeled dorsal scales at midbody (5 vs 7–13); by enlarged vertebral scales (vs not enlarged); by a higher number of ventrals (182 vs 151–173); by a higher number of subcaudals (71 vs 39–53); and by different colouration of body (cream vs dark grey). Pareas sp. differs from P. margaritophorus by loreal contacting eye (vs not contacting); by the absence of preoculars (vs presence); by comparatively short temporal scales (vs elongated); by 5 keeled dorsal scale rows at midbody (vs all smooth); by enlarged vertebral scales (vs not enlarged); by a higher number of ventrals (182 vs 133–160); by a higher number of subcaudals (71 vs 35–54);and by different body colouration (cream vs dark grey). Pareas sp. differs from P. mengziensis by cream colouration of dorsum with indistinct darker crossbars (vs solid black marking on back of head extending to dorsum); by loreal contacting eye (vs not contacting); by preoculars absent (vs present); by a single row of enlarged vertebral scales (vs 3 rows); by a greater number of ventrals (182 vs 167–173); and by the absence of 2 black postorbital stripes (vs presence). Pareas sp. differs from P. modestus by loreal contacting eye (vs not contacting); by comparatively short temporal scales (vs elongated); by enlarged vertebral scales (vs not enlarged); by a higher number of ventrals (182 vs 151–159); by a higher number of subcaudals (71 vs 35–46); and by different colouration of body (cream vs dark grey). Pareas sp. differs from P. nigriceps by loreal contacting eye (vs not contacting); by the presence of two anterior temporals (vs single); by subocular and postocular not fusing into a crescent-shaped scale (vs fused); and by slightly lower number of subcaudals (71 vs 73–77). Pareas sp. can be distinguished from P. nuchalis by frontal shape (subhexagonal with the lateral sides converging posteriorly vs hexagonal with the lateral sides parallel); by the anterior pair of chin shields longer than broad (vs broader than long); by loreal contacting eye (vs not contacting); by 5 keeled dorsal scale rows at midbody (vs all smooth); by 2 anterior temporals (vs three); by a lower number of ventrals (182 vs 201–220); and by a lower number of subcaudals (71 vs 102–120). Pareas sp. differs from P. stanleyi by supralabials not touching the eye (vs regularly touching);by a lower number of keeled dorsal scales at midbody (5 vs 13); by preoculars present (vs absent); by vertebral scales enlarged (vs not enlarged); by a higher number of ventrals (182 vs 151–160); by a higher number of subcaudals (71 vs 48–60); and by the absence of postorbital stripes (vs presence). Pareas sp. can be distinguished from P. vindumi by the presence of preoculars (vs absence); by the absence of presuboculars (vs presence); by 5 keeled dorsal scale rows at midbody (vs all smooth); by enlarged vertebral scales (vs not enlarged); by a higher number of subcaudals (71 vs 61); by the presence of a dark collar (vs absence); and by the presence of dark bands on body (vs absence). Pareas sp. can be distinguished from the superficially similar species P. monticola by 5 keeled dorsal scale rows at midbody (vs all smooth); by eye separated from supralabials by subocular scales (vs 4th or 4th–5th SL touching eye); by the absence of postorbital stripes (vs presence); and by lateral and ventral surfaces of head with dense brownish dusting (vs head ventrally immaculate, laterally with a few dark spots). Finally, Pareas sp. differs from Pareas victorianus sp. (described above) by the presence of preoculars (vs absence); by a slightly lower number of keeled dorsal scales at midbody (5 vs 7); by a higher number of ventrals (182 vs 164); by a higher number of subcaudals (71 vs 58), by 2nd–5th SL touching the subocular (vs 3rd–5th); by the absence of postorbital stripes (vs presence); and by lateral and ventral surfaces of head with dense brownish dusting (vs head ventrally immaculate, laterally with a few dark spots).

Distribution and ecology notes. Pareas sp. is presently known from a single specimen collected in a mountain forest in the northernmost part of Kachin State, in the Myanmar portion of Eastern Himalaya ( Figure 1 , locality 19). Further records of the new species from the foothills of adjacent portions of Eastern Himalaya in south-western China (Yunnan Province) and north-eastern India (Arunachal Pradesh State) are anticipated. Ecological data on Pareas sp. are minimal. The specimen was found at elevation of ca. 1010 m asl at 21:16 h on the ground near a mountain stream; the ambient air temperature at the time of collection and the relative humidity were 19.4°C and 64%, respectively, according to the CAS specimen database (see http://portal.vertnet.org/o/ cas/herp?id=urn-catalogue-cas-herp-224415, accessed in May 2020). Habitats at these elevations comprise evergreen forests and mixed deciduous forests with a predominance of trees including Wightia gigantea (Paulowniaceae) , Dipterocarpus alatus (Dipterocarpaceae) , Elaeocarpus sp. (Elaeocarpaceae) , Nephelium sp. (Sapindaceae) , Bauhinia sp. (Fabaceae) , Schima sp. (Theaceae) , Fagraea sp. (Gentianaceae) and various Magnoliaceae , with a dense undergrowth of shrubs, such as Rhododendron simsii (Ericaceae) , Homonoia riparia (Euphorbiaceae) , Ficus spp. (Moraceae) , Camellia sp. (Theaceae) and Euonymus sp. (Celastraceae) ( Khin and Aung 2002).

Figures

Figure 1. Map showing distribution of the Pareas monticola species complex and locations of the studied populations. Circles denote localities for which both DNA and morphological data were examined; diamonds denote localities for which only morphological data were available; triangles denote populations for which only DNA data were available; a dot in the centre of an icon indicates a type locality; question marks denote unconfirmed and historical records. Abbreviations: BAN. = Bangladesh; BHU. = Bhutan. Localities. Pareas monticola: BHUTAN: 1 – Bhutan, no exact locality (Lenz 2012); BANGLADESH: 2 – Lawachara NP, Moulvibazar, Sylhet (Das and Das 2017; Hakim et al. 2020); INDIA: 3 – Darjiling, West Bengal; 4 – Khasi Hills, Meghalaya; 5 – Jampui Hills, Tripura; 6 – Mizoram; 7 – Naga Hills, Assam (type locality of Dipsas monticola Cantor, 1839); 8 – Orang, Assam (Deepak et al. 2020); 9 – Abor Hills, Arunachal Pradesh; 10 – Mishmi Hills, Arunachal Pradesh; MYANMAR: 11 – Indawgyi NR, Myitkyina, Kachin; 12 – Banmauk, Sagaing; CHINA: 13 – ‘Medog’ (= Motuo), Xizang (Guo et al. 2011; Li et al. 2020; Wang et al. 2020); 14 – Linzhi, Motuo, Xizang; 15 – Longchuan, Yunnan (Yang and Rao 2008); 16 – Pingbian, Yunnan (Wang et al. 2020); VIETNAM: 17 – ‘Chapa’ (= Sa Pa), Lao Cai (Bourret 1936); 18 – Tam Dao, Vinh Phuc (Orlov et al. 2003); Pareas sp.: MYANMAR: 19 – Hkakabo Razi NP, Putao, Kachin; Pareas victorianus sp. nov.: MYANMAR: 20 – Nat Ma Taung Mt., Mindat, Chin (type locality). Photo showing P. monticola from Sagaing, Myanmar, by N.A. Poyarkov. Abbreviations: BAN. = Bangladesh; BHU. = Bhutan.

Figure 4. Comparison of head scalation in lateral view of the type specimens of Pareas monticola complex members: a: Pareas monticola holotype (BM(NH) 1946.1.20.5, adult male); b: Pareas victorianus sp. nov. holotype (CAS 224415, adult male); c: Pareas sp. from Kachin State (CAS 235254, adult female). Drawings by L.B. Salamakha.

Figure 7. Pareas sp. from Kachin State in preservative (CAS 235254, adult female): (a–b): Dorsolateral and ventral view of body, respectively; (c–f): head in lateral right, lateral left, dorsal, and ventral aspects, respectively. Photos by G. Vogel.