Myanophis thanlyinensis, Köhler & Khaing & Than & Baranski & Schell & Greve & Janke & Pauls, 2021

Köhler, Gunther, Khaing, Khin Pa Pa, Than, Ni Lar, Baranski, Damian, Schell, Tilman, Greve, Carola, Janke, Axel & Pauls, Steffen U., 2021, A new genus and species of mud snake from Myanmar (Reptilia, Squamata Homalopsidae), Zootaxa 4915 (3), pp. 301-325 : 308-311

Myanophis thanlyinensis gen. nov., sp. nov.

Gunther Köhler, Khin Pa Pa Khaing, Ni Lar Than

ZOOBANK urn:lsid:zoobank.org:act:68106D4B-425B-4094-A6D3-81C4C42FEFB7

Figs. 5–6 ; Table 2

Holotype. SMF 100707, an adult male from wetlands near campus of East Yangon University (16.74255, 96.28307; 6 m a.s.l.), Thanlyin, Yangon, Myanmar, collected on 5 of November 2019 by Ni Lar Than and Gunther Köhler. Original field tag GK-7730.

Paratypes. EYU PaPa-0023 and SMF 100709 (original field tag PaPa-0019), two adult females from wetlands near campus of East Yangon University (16.740297, 96.285184; 6 m a.s.l.), Thanlyin, Yangon, Myanmar, collected on 14 of September 2018 by a local fishermen and received by Khin Pa Pa Khaing. SMF 100708 (original field tag GK-7731), an adult male from wetlands near campus of East Yangon University (16.74275, 96.31250; 6 m a.s.l.), Thanlyin, Yangon, Myanmar, collected on 15 of October 2019 by a local fishermen and received by Ni Lar Than.

Diagnosis. A species of the genus Myanophis that differs from all other homalopsid species by the following combination of characters: (1) dorsal scales smooth, row formula 21–21–19 or 21–21–17; (2) tail short, ratio TaL/SVL 0.185 –0.204 in males, 0.160 –0.167 in females; (3) nasal scales separated; (4) 125–126 ventral scales in males, 120–122 in females; (5) 38–39 subcaudal scales in males, 32–34 in females; and (6) hemipenis bilobed. Phylogenetically, (based on analyses of 16S and MT-CYB sequences), Myanophis thanlyinensis gen. nov. , sp. nov. differs from its closest relatives, Myrrophis and Gyiophis , by having a bilobed hemipenis (vs. unilobed). Further, Myanophis thanlyinensis gen. nov. , sp. nov. differs from the species of Myrrophis by having 125–126 ventral scales in males, 120–122 in females (vs. 137–162, 137–164, respectively), and 38–39 subcaudal scales in males, 32–34 in females (vs. 39–55, 37–52, respectively). Myanophis thanlyinensis gen. nov. , sp. nov. differs further from the species of Gyiophis by lacking dark blotches along flank (vs. having blotches), and by having 21 dorsal scales rows at midbody (vs. 25 scales). The following other homalopsid species share with M. thanlyinensis gen. nov., sp. nov. the combination of having smooth dorsal scales in 21 rows at midbody, reducing to 17 or 19 rows anterior to vent and fewer than 130 ventral scales: Enhydris chanardi , E. innominata , E. jagorii , and E. longicauda . However, all species have more than 50 subcaudal scales in males and more than 40 in females (vs. 38–39, 32–34, respectively, in M. thanlyinensis gen. nov., sp. nov.), and a TaL/SVL of> 0.22 in males, and> 0.17 in females (vs. 0.185–0.204, 0.160–0.167, respectively).Also, Enhydris jagorii and E. longicauda have 23–27 dorsal scales rows on neck (vs. 21 in Myanophis Thanlyinensis gen. nov. , sp. nov.).

Description of the holotype ( Figs. 5 & 6 ). Adult male, indicated by fully developed everted hemipenes; head depressed, distinct from neck; snout short and rounded, rostrum tapers downwards; rostral scale pentagonal, nearly as broad as tall, visible from above; eye moderate in size, pupils round; nasals divided with nasal groove contacting first supralabial; internasal squarish, not in contact with loreal; loreals 1/1, quadrangular, contacting first three supralabials; preocular 1/1; supraocular 1/1; postoculars 2/2; prefrontals 2, in broad contact with each other, frontal, internasal, loreals, preoculars, supraoculars, and nasals; frontal roughly pentagonal, 1.4 times longer than supraocular; parietals elongate; temporal scale formula 1 + 2 + 3; supralabials 8/8, 4th supralabial entering orbit; infralabials 10/10, first five in contact with anterior chin shield; anterior pair of chin shields larger than second pair, the former in contact with each other, the latter separated medially from each other by two smaller scales; 21 ASR, 21 MSR, 19 PSR; dorsal scales smooth without scale pits; 126 ventrals; cloacal plate divided; subcaudal scales 39. Body short, somewhat stocky; tail short (TaL/SVL 0.2038); SVL 260 mm; TaL 53 mm.

Coloration in life ( Fig. 5 ; colors in parentheses according to Köhler 2012): Dorsal ground color Olive Brown (color 278), scale rows 4 and 5 slightly darker (Sepia 286) and scale rows 1 to 3 Pale Cinnamon (55) with Hair Brown (277) blotch on anterior portion of each scale; ventral scales Pale Cinnamon (55) with Hair Brown (277) suffusion of anterior portion of each scale; iris Olive Brown (278).

Coloration after about three months in preservation in 70% ethanol agrees well with the description of coloration in life.

Variation. Paratypes agree well with the holotype in general appearance, morphometrics and scalation ( Table 2 ). Strong sexual dimorphism is evident in the number of ventral and subcaudal scales that show non-overlapping values between males and females.

Etymology. The species epithet refers to the city of Thanlyin, a major port city of Myanmar, located across the Bago River southeast of the city of Yangon, where the type series of M. thanlyinensis gen. nov., sp. nov. was collected.

Natural history notes. The type locality is open grassland ( Fig. 7 ), mostly flooded during the rainy season with only a few scattered wooden houses, adjacent to the campus of East Yangon University (EYU), Thanlyin, Myanmar. The snakes were caught at night with the help of local fishermen in shallow water (<50 cm depth) with an abundance of grassy vegetation. Syntopic with M. thanlyinensis gen. nov., sp. nov. we collected the homalopsid species Enhydris enhydris and Gyiophis vorisi ( Fig. 8 ) as well the semiaquatic colubrids Amphiesma stolatum , Xenochrophis bellulus , and X. piscator . Of these syntopic species, E. enhydris was the by far most abundant snake at this site with>20 individuals encountered per night-search.

Geographic Distribution and Conservation. As currently known, Myanophis thanlyinensis gen. nov., sp. nov. is only known from the vicinity of its type locality. Given the little we know about this species, we classify M. thanlyinensis gen. nov., sp. nov. as Data Deficient based on the IUCN Red List Categories and Criteria ( IUCN 2012).

Figures

FIG. 5. Holotype (SMF 100707) of Myanophis thanlyinensis gen. nov., sp. nov. in life. Photograph by G.K.

FIG. 6. Holotype (SMF 100707) of Myanophis thanlyinensis gen. nov., sp. nov.: (A) dorsal view; (B) ventral view; (C) left lateral head; (D) right lateral head; (E) dorsal head; (F) ventral head; (G) lateral body; (H) cloacal region with everted hemipenes. Scale bars equal 10.0 mm in A and B, and 5.0 mm in C to H. Photographs by G.K.

FIG. 7. Habitat of Myanophis thanlyinensis gen. nov., sp. nov. near the type locality (near campus of East Yangon University, Thanlyin, Yangon, Myanmar). Photograph by G.K, taken on 23 June 2019.

FIG. 8. Homalopsid species in life, collected at the type locality (near campus of East Yangon University, Thanlyin, Yangon, Myanmar) of Myanophis thanlyinensis gen. nov., sp. nov.: (A) Gyiophis vorisi (SMF 100700); (B) Enhydris enhydris (GK- 7158). Photographs by G.K.

Tables

TABLE 2. Variation in selected characters of external morphology in type series of Myanophis thanlyinensis gen. nov., sp. nov. For abbreviations see main text.

	SMF 100707 Holotype	SMF 100708 Paratype	SMF 100709 Paratype	EYU PaPa-0023 Paratype
Sex	male	male	female	female
SVL	260	335	362	300
TaL	53	62	58	50
TaL/SVL	0.204	0.185	0.160	0.167
SV	126	125	122	120
ScS	39	38	34	32
PrOc	1	1	1	1
LoS	1	1	1	1
PoOc	2	2	2	2
TempA	1	1	1	1
TempP	2	2	2	2
SPL	8	8	8	8
SPL-Oc	4	4	4	4
IFL	10	10/9	10	10
ASR	21	21	21	21
MSR	21	21	21	21
PSR	19	19	17	17
ClS	entire	entire	entire	entire