Cylindrophis slowinskii, Bernstein & Bauer & Mcguire & Arida & Kaiser & Kieckbusch & Mecke, 2020

Bernstein, Justin M., Bauer, Aaron M., Mcguire, Jimmy A., Arida, Evy, Kaiser, Hinrich, Kieckbusch, Max & Mecke, Sven, 2020, Molecular phylogeny of Asian pipesnakes, genus Cylindrophis Wagler, 1828 (Squamata: Cylindrophiidae), with the description of a new species from Myanmar, Zootaxa 4851 (3), pp. 535-558 : 540-545

Cylindrophis slowinskii sp. nov.

( Fig. 4 )

Holotype. CAS 241554 (field number: CAS-MHS 26113 ), an adult specimen from Indawgyi Wildlife Sanctuary in the vicinity of Lwe Mon Village , west of Indawgyi Lake, Mohnyin Township, Kachin State, Myanmar (ca. 25.1787° N, 96.2917° E, elevation 245 m), collected by J.A. Wilkinson, K.T. Kyaw, and J.V. Vindum on 26 July 2008 ( Fig. 4 ).

Paratype. USNM 590030 (field number: CAS-MHS 26114 ), an adult specimen, collection data as for the holotype .

Diagnosis. A species of the genus Cylindrophis , identified by a combination of the following characteristics: (1) small size: 297–333 mm SVL; (2) 17-19-17 dorsal scale rows; (3) 216–220 ventrals; (4) eight subcaudals; (5) 65–69 very narrow diffuse pale ventral blotches that are branching, creating the impression of a diffuse reticulum; and (6) a pale bar running along the posterior border of the prefrontals ( Fig. 4 ). These morphological characters are sufficient to distinguish C. slowinskii from all other species of Asian pipesnakes.

Description of the holotype. Metrics. A relatively short body, 333 mm SVL + 7 mm TL = 340 mm TTL (336 mm in life), tail blunt and very short (2% of SVL); BD 7.4 mm (2.2% of SVL); head not wider than body, HL 7.4 mm (2.2% of SVL), HW 4.9 mm (66.2% of BD); snout rounded in dorsal and lateral views, relatively long, 2.7 times as long as diameter of the eye, SL 3.4 mm (45.9% of HL), SW 2.8 mm; a small eye, ED 0.9 mm (12.1% of HL); IOD 3.3 mm; IND 2.0 mm; rostral height 1.2 mm, width 1.6 mm; paired nasals, length of a single nasal 1.1 mm, width 1.8 mm; paired prefrontals, length of a single prefrontal 1.6 mm, width 1.9 mm; frontal length 2.0 mm, width 1.6 mm; paired parietals, length of a single parietal 1.7 mm, width 1.5 mm; paired supraoculars, length of a single supraocular 1.9 mm, width 1.5 mm; postocular length 0.7 mm, height 0.8 mm; anterior temporal length 1.2 mm, height 1.6 mm, upper posterior temporal length 1.5 mm, height 0.8 mm; mental height 0.7 mm, width 1.3 mm; two pairs of chin shields, anterior chin shield length 1.8 mm, width 1.6 mm, posterior chin shield length 1.5 mm, width 1.0 mm; mental groove length 3.1 mm. The holotype weighed 12.5 g in life.

Scale counts and qualitative pholidosis. 17-19-17 dorsal scale rows; 220 ventrals; eight subcaudals + terminal spine; postnasal, loreal, preocular, and subocular absent; temporal formula 1 + 2; six supralabials, 3 rd and 4 th contacting the eye; six infralabials; cloacal scute divided; scales on head, trunk, and tail smooth; apical pits absent.

Coloration and pattern in preservative (after 11 years in ethanol). Dorsal surface Jet Black (300), with 31 transverse Pale Buff (1) to Chamois (84) blotches from nape to tail; blotches may be complete or medially interrupted, if interrupted both parts may alternate; first four blotches approximately one scale wide, blotches covering medial part of the body narrowest, covering scale margins only, last dorsal blotch broad, dorsal blotch on the tail Pale Pinkish Buff (3), merging onto the subcaudal region, tail tip dark; a pale bar runs from the border of the prefrontals with the frontal towards the upper margin of the 3 rd supralabials, leaving the margin of the prefrontals with the supraoculars dark; posterior half of 3 rd supralabial with a pale blotch, slightly connected with the prefrontal bar on the right side only; margin of 5 th labial pale; frontal with a pale median blotch; scales on ventral surface of head almost always with pale margins (except for the mental and 1 st labials); ground color of venter as for dorsum; 69 pale and very narrow diffuse ventral blotches present, branching, and therefore creating the impression of a diffuse reticulum.

Variation. The paratype (USNM 590030) differs from the holotype (CAS 241554) as follows (metrics of head scales excluded): 297 mm SVL + 8 mm TL = 305 mm TTL; 216 ventrals; 65 pale ventral blotches. In terms of color pattern, the paratype is very similar to the holotype. The bar on the prefrontals is not in contact with the pale color of the supralabials on both sides. All supralabials (except for the 1 st and 2 nd on the right side) have pale markings.

Comparisons with other species. Cylindrophis slowinskii (n = 2; characters listed in parentheses below), yet alone differs from all congeners by a combination of unique scalation characters, including 17-19-17 dorsal scale rows, a high number of ventrals (216–220), and eight subcaudals. Cylindrophis aruensis possesses 23 (19) dorsal scale rows at midbody, 173−182 (216−220) ventrals, six or seven (eight) subcaudals, 44 (65−69) pale ventral blotches, and pale stripes on the head, running from the nasals onto the posterior temporals (a pale bar on the prefrontals, no pale markings posterior to the eyes) ( Boulenger 1920; McDowell 1975; Lang 2013; Amarasinghe et al. 2015). Cylindrophis boulengeri (n = 4) possesses 195−204 (216−220) ventrals, five or six (eight) subcaudals, 48−54 (65−69) pale ventral blotches, and pale wavelike markings along the labials that may run onto the prefrontals but are never connected to form a bar (no wavelike markings on the labials, a pale bar on the prefrontals). Cylindrophis burmanus (n = 20) possesses 190− 2202 [median = 209] (216−220; median = 218) ventrals, four to seven (eight) subcaudals, and 29−61 (65−69) pale ventral blotches. Cylindrophis engkariensis (n = 1) possesses 17 (19) dorsal scale rows at midbody, 230 (216−220) ventrals, five (eight) subcaudals, rugose (smooth) dorsals on the tail, 45 (65–69) pale ventral blotches, a dorsal pattern of two paravertebral rows of dark spots (transverse pale dorsolateral blotches), a pale postocular streak (no postocular streak), and dark prefrontals (a pale bar on the prefrontals). Cylindrophis isolepis (n = 2) is a relatively large species with a maximum SVL of 500 mm (333 mm; see Amarasinghe et al. 2015) and possesses 21 (19) dorsal scale rows at midbody, five or six (eight) subcaudals, nasals that are separated by the rostral (nasals in contact), 27−35 (65–69) pale ventral blotches that are reddish in living specimens, and no markings on the dorsal surface of the head (a pale bar on the prefrontals). Cylindrophis jodiae (n = 90) is a relatively large species with a maximum SVL of 786 mm (333 mm) and possesses 21 (19) dorsal scale rows at midbody, 177−201 (216−220) ventrals, five to seven (eight) subcaudals, 30−55 (65−69) pale ventral blotches, pale wavelike markings along the labials or heavily blotched labials (labials without prominent pattern), and dark prefrontals (a pale bar on the prefrontals). Cylindrophis lineatus (n = 1) is a relatively large species with a maximum SVL of 713 mm (333 mm) and possesses 21 (19) dorsal scale rows at midbody, 210−218 (216−220) ventrals, 31 (65−69) pale ventral blotches, a dorsal pattern of stripes that are red and black in living specimens (transverse pale dorsolateral blotches), a pale dorsal surface of head and tail, both being red in living specimens (no extensively colored dorsal surface of head and tail), and dark markings on the temporals and parietals (head uniformly dark with a pale bar on the prefrontals) (see also Amarasinghe et al. 2015). Cylindrophis maculatus (n = 36) possesses 27−49 (65−69) pale ventral blotches, a dorsal pattern of large and roundish, paired pale blotches separated by a narrow dark network, with the blotches being reddish-brown in living specimens (very narrow and widely separated transverse pale blotches on a dark dorsum), and prefrontals that lack a pale bar (a pale bar on the prefrontals). Cylindrophis melanotus (n = 39) is a relatively large species with a maximum SVL of 678 mm (333 mm) and possesses 228−268 (216−220) ventrals and 38−63 dark blotches on a pale-colored venter that is reddish or white in living specimens (65−69 very narrow diffuse pale blotches on a dark-colored venter). Cylindrophis opisthorhodus (n = 6) possesses 23 (19) dorsal scale rows at midbody, 185−210 (216−220) ventrals, four to seven (eight) subcaudals, 46−61 (65−69) pale ventral blotches, a pale dorsum with dark speckles forming two paravertebral rows and occasionally a discontinuous vertebral line (very narrow transverse pale blotches on a dark dorsum), and dark speckles on the pale dorsal surface of the head (head uniformly dark with a pale bar on the prefrontals) (see also Amarasinghe et al. 2015). Cylindrophis osheai (n = 3) possesses 224–226 (216–220) ventrals, 25−28 dark ventral blotches, aligned to form a broad wavy stripe along most of the otherwise pale underside (venter almost entirely black with 65–69 diffuse pale blotches), and no pale bar on the prefrontals (a pale bar on the prefrontals). Cylindrophis ruffus (n = 244), as defined by Kieckbusch et al. (2016), is a relatively large species with a maximum SVL of 857 mm (333 mm) and possesses five to seven (eight) subcaudals and 33−66 (65–69) pale ventral blotches. Cylindrophis subocularis (n = 9) possesses a subocular scale (no subocular scale), 190−196 (216−220) ventrals, six or seven (eight) subcaudals, and 40−48 pale ventral blotches that are usually as broad as the dark blotches (65–69 very narrow diffuse pale blotches that are widely separated by dark color). Cylindrophis yamdena (n = 5) is a relatively large species with a maximum SVL of 671 mm (333 mm) and possesses 21 (19) dorsal scale rows at midbody, 183−195 (216−220) ventrals, and no pattern on the dorsal surface of the body and no ventral blotches in adults (a pale bar on the prefrontals, pale blotches on the dorsum and venter).

Geographic distribution, habitat, and natural history. Cylindrophis slowinskii might have a more isolated distribution with regard to the other species of the genus and is only known from its type locality in northern Myanmar near Indawgyi Lake ( Fig. 5 ). As the type specimens were found under logs in forests, C. slowinskii is assumed to be a secretive forest-dweller with a semi-fossorial lifestyle, as typical for most species of Asian pipesnakes. Due to the limited number of available specimens, the complete geographic distribution and biogeographic history of C. slowinskii is uncertain. However, the physiography of northern Myanmar, especially Kachin State, is characterized by scattered stretches of mountains that may act as dispersal and gene flow barriers for species of Cylindrophis . Additionally, major rivers such as the Irrawaddy River, and its largest tributary, the Chindwin River, may also largely act as barriers to gene flow. These biogeographic hypotheses, however, can only be tested using more complex analyses, divergence dating estimates, and a more complete sampling of C. slowinskii and the closely related C. burmanus (see “Remarks on the type series”, below).

Etymology. The specific epithet is a patronym to honour the American herpetologist Joseph Bruno “Joe” Slowinski (1962–2001) and his pioneering work on herpetofauna, especially in Myanmar. In 2001, Joe led a multidisciplinary expedition to Kachin State, Myanmar, the type locality of the new species described herein. For biographical details see Donnelly & Crother (2003) and James (2008).

Suggested common names. Slowinski’s pipesnake (English), Slowinski-Walzenschlange (German),

Remarks on the type series of the closely allied Cylindrophis burmanus . The Asian pipesnake Cylindrophis burmanus was originally described as a subspecies of “ C. ruffus ” by Malcolm Arthur Smith (1875–1958) based on an unspecified number of vouchers. The distributional range of this new taxon was given as “Tenasserim and Burma as far North as Myitkyina” (today’s Myanmar) without the restriction of a precise type locality. Amarasinghe et al. (2015) designated a lectotype (BMNH 1940.3.3.1) from “the presumed type series” (i.e., the syntypes) and listed five additional specimens housed in the collection of the BMNH that they designated as paralectotypes (see also Kieckbusch et al., 2016).

Although Smith (1943; probably based on Wall (1925)) listed Tenasserim, today’s Tanintharyi Region, as the southern limit for the distribution of Cylindrophis burmanus , we were not able to confirm the presence of this species south of the Irrawaddy Delta based on voucher specimens. A single, more recent record (JMB & SM, pers. obs.) for an Asian pipesnake from the Tanintharyi Region can be identified as C. jodiae .

The lectotype (definitive type) of Cylindrophis burmanus was collected from Yangon (today’s Rangoon; see Fig. 5 ), the most famous port in the Irrawaddy Delta, and capital of all Myanmar ( Burma) from 1886 to 2005. Based on its collection locality, this specimen likely belongs to the population that is found in the Irrawaddy Delta and east of the Irrawaddy River and that we identified using molecular genetic methods ( Fig. 5 ). Among all the vouchers of C. burmanus we have examined (n = 20; see “Appendix 2”), only a single specimen (BMNH 1925.12.22.4; paralectotype) was collected from the temperate hilly zone in northern Myanmar that is enclosed by the Chindwin and Irrawaddy Rivers (see Wall (1926)), and only ~ 50 km away from the type locality of C. slowinskii , the latter located at the western side of Indawgyi Lake. Indawgyi Lake is enclosed by hilly country as well, with the Loipyet Range acting as a potential barrier to the east. The collection locality of BMNH 1925.12.22.4 (Sahmaw; part of the Myitkyina District when the specimen was collected) is located in the lowlands east of this mountain range. Based on morphology (214 ventrals, seven subcaudals, 52 pale ventral blotches) this paralectotype identifies as C. burmanus .

Figures

FIGURE 4. Holotype of Cylindrophis slowinskii sp. nov. (CAS 241554) from Kachin State, Myanmar in dorsal (A) and ventral (B) view. The head is shown in lateral (C) and dorsal (D) view, the tail in ventral view (E). The 10 mm and 5 mm scale bars are for panels A+B and C+D+E, respectively. Photos by Justin M. Bernstein.

FIGURE 5. Collection localities of the specimens of Cylindrophis burmanus (green symbols) and Cylindrophis slowinskii (blue circles) used for our molecular analyses. Symbols in the maps correspond to the ones used for the different clades in the accompanying tree. Major clades of C. burmanus are distinguished by green circles and squares. The orange diamond represents the collection locality of the lectotype of C. burmanus (BMNH 1940.3.3.1 from Yangon (Rangoon); specimen not included in phylogenetic analysis). In the country map of Myanmar, higher elevations appear in brighter and lower elevations in darker shades of green; the Chindwin and Irrawaddy Rivers are marked in yellow and purple, respectively; the Arakan Mountain range is highlighted with yellow triangles. The satellite map is a detailed magnification of the area shaded purple in the country map. An arrow in the inset map indicates where the Irrawaddy splits into its delta. Note that the three green squares in the satellite image represent near-overlapping localities of the southern population of C. burmanus that appear as a single symbol in the larger map. Satellite map obtained from Google Earth v7.3.2.5776: Image © 2019 TerraMetrics Data SIO, NOAA, U.S. Navy, NGA, GEBCO. Map prepared by Justin M. Bernstein.