Trimerodytes balteatus COPE, 1895
Can you confirm these amateur observations of Trimerodytes balteatus?
|Higher Taxa||Colubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||E: Hainan Mountain Keelback|
|Synonym||Trimerodytes balteatus COPE 1895: 426|
Opisthotropis balteata POPE 1935
Liparophis Bedoti PERACCA 1904: 664
Opisthotropis multicinctata FAN 1931: 82
Opisthotropis multicincta FAN 1931 (fide ZHAO & ADLER 1993)
Trimerodytes balteatus — MELL 1931 
Opisthotropis balteatus — SMITH 1943: 331
Opisthotropis balteatus — BROWN & LEVITON 1961
Opisthotropis balteata — ZIEGLER et al. 2008
Opisthotropis balteata — WALLACH et al. 2014: 508
Trimerodytes balteatus — REN et al. 2019: 117
Trimerodytes balteata — FRANCIS 2021
|Distribution||N Vietnam, China (Hainan, Guangdong, Guangxi, Hunan, Hong Kong)|
Type locality: Hainan Island, China.
|Types||Holotype: ANSP 11435; MCZ ?|
|Diagnosis||Diagnosis Trimerodytes balteatus can be diagnosed from other morphologically similar species by a combination of the following characters: (1) body cylindrical, TL 604–1 021 mm; (2) tail relatively moderate, TaL/TL 0.15–0.24; (3) head moderately distinct from neck; (4) nostrils directed dorsolaterally; (5) eyes moderate, EW/ SoL 0.86–1.38; (6) maxillary teeth mostly 16–19, slightly enlarged posteriorly, without diastema; (7) dorsal scale rows 19-19-17; (8) prefrontal single, spindle-shaped; (9) supralabials 9–10, usually 4th or 5th entering orbit; (10) ventrals 187–205; (11) dorsal scales smooth anteriorly, smooth or feebly keeled at midbody, tending to be moderately keeled rear body and on tail, outer most three or four dorsal scale rows along both sides of body smooth entirely before cloaca; (12) body brownish-red or brownish-yellow, encircled by 32–54 black bands with yellow centers, 13–28 present on tail; (13) venter yellowish-beige, with annulated or alternating black bands (Figures 2A, 3D, 4, 5A–B; Tables 3–4 in Ren et al. 2019).|
Comparison Trimerodytes balteatus can be readily distinguished from other species of Trimerodytes by having a single prefrontal (vs. paired prefrontals), and a higher number of ventral scale count (187–205 vs. less than 170). In addition, T. balteatus differs from T. yunnanensis by having a lower number of maxillary teeth [16–19 (25?) vs. 31–35] and a different dorsal color pattern (body annulated by transverse markings vs. crossed by X-shaped markings); from T. aequifasciatus by having a moderately distinct head (vs. distinct) and a higher number of trunk markings (32–54 vs. 22–28); from T. percarinatus by having moderately keeled dorsal scales at midbody (vs. strongly keeled throughout) and the presence of labial sutures (vs. absent). Lastly, T. balteatus differs from its sister species, T. annularis, in having a different head color pattern (black streaks present on dorsal surface vs. absent) and a different background color of ventral surface (uniformly yellowish vs. red or reddish-orange).
From other natricine taxa that have single prefrontal, T. balteatus differs from the genus Isanophis by its head moderately distinct from neck (vs. well distinct), eye size moderate (vs. large), and moderately keeled posterior dorsal scales (vs. strongly keeled throughout); from the genus Opisthotropis see above; from the genus Trachischium by having a different dorsal scale formula (19-19-17 vs. 13 or 15 throughout), a different maxillary condition (maxillary teeth enlarged posteriorly vs. subequal), and head moderately distinct from neck (vs. indistinct); from Hebius annamensis (Bourret, 1934) by having 19 rows of dorsal scales at the midbody (vs. 15 or 17), a lower number of subcaudals (65–102 vs. 116–146), and a higher number of ventrals (187–205 vs. 158–172); from Rhabdops bicolor by having paired internasals (vs. single), and a higher number of supralabials (9–10 vs. 5) (Table 6 in Ren et al. 2019).
|Comment||Habitat: aquatic, inhabiting flowing streams.|
Synonymy: partly after Zhao & Adler 1993.
Diet: fishes, frogs, tadpoles, freshwater shrimp and earthworms.
Type species: Trimerodytes balteatus COPE 1895: 426 is the type species of the genus Trimerodytes COPE 1895. Trimerodytes was resurrected from the synonymy of Opisthotropis as a senior synonym of Sinonatrix (which was synonymized with Trimerodytes by Ren et al. 2019).
Comparisons (genera): Ren et al. 2019: 121 (Table 6) provide a morphological comparison of natricine genera (Opisthotropis, Paratapinophis, Isanophis, Trimerodytes balteatus, Hebius annamensis, Trachischium fuscum/guentheri, Rhabdops bicolor, Atretium yunnanensis, Pseudagkistrodon rudis multiprefrontalis).
Distribution: not in Cambodia fide Ren et al. 2019.
|Etymology||The generic nomen of Trimerodytes is a noun made of three parts: (1) the Ancient Greek τρία “tría”, meaning “three”; (2) the Ancient Greek μέρος “méros”, meaning part, component, or region; and (3) the Greek “dytēs”, meaning diver or swimmer. The generic nomen refers to the three-parted (black-yellow-black) annulated markings and the aquatic life of the type species T. balteatus. The gender of this generic name is masculine (Ren et al. 2019).|
The specific epithet, balteatus, is a Latin adjective that means girded or belted. The term may be used to describe the distinctive annulated markings of this species.
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