Calamaria yunnanensis Chernov, 1962

Lee, Justin L., 2021, Description of a new species of Southeast Asian reed snake from northern Laos (Squamata: Colubridae: Genus Calamaria F. Boie, 1827) with a revised diagnosis of Calamaria yunnanensis Chernov, 1962, Journal of Natural History 55 (9 - 10), pp. 531-560 : 548-555

Calamaria yunnanensis Chernov, 1962

Calamaria yunnanensis: Chernov 1962: 383 , in: ‘On one yet unknown snake in the genus Calamaria from Yunnan (Scientific results of the Chinese–Soviet expeditions in 1955–1957 to South-Western China)’. Proceedings of the Zoological Institute, Academy of Science of the USSR, Leningrad, 30, 382–384, Inger and Marx (1965: 238), Yang and Inger (1986: 10), Zhao and Adler (1993: 232), Ziegler and Quyet (2005: 36), Zhao (2006: 184), Stuart and Heatwole (2008: 98 in part), Yang and Rao (2008: 275), Ziegler et al. (2008: 78), Orlov (2009: 152), Nguyen et al. (2009: 3), Koch et al. (2009: 20), Zaher et al. (2009: 138), Orlov et al. (2010: 239), Vogel and Luo (2011: 36), Yang and Zheng (2018: 485 in part), Ziegler et al. (2019: 23), Poyarkov et al. (2019: 341 in part), Wallach et al. (2014: 142, in part), Weinell et al. (2021: 3 in part).

Holotype. NZMC, original catalogue number ZISP 17073 ( Figure 1 (b)), collected ‘ in the vicinity of Tszindun, in the gorge of monsoon forest 1100–1200 meters’ [= in the vicinity of Jingdong, Jingdong Yi Autonomous County, southern Yunnan Province, China] a male specimen (maturity unknown) collected on 31 May 1956 by Soviet Researcher Alexei K. Zaguliayev, as part of the joint Soviet–Chinese field expeditions to Yunnan Province, China. A translation of the original description can be found in the Supplementary data. Topotypic specimens. ( Figure 5 ). KIZ 054176 (alternate catalogue: 75II0198 ), an adult female collected from Jingdong Yi Autonomous County, southern Yunnan Province, China (same locality as the type specimen) on 11 May 1975 (collector unknown); KIZ 056010–011 (alternate catalogues: 75II0224–225 , respectively), two males from the same locality collected on 10 June 1975 (collector unknown); and KIZ 056009 , sex unknown, from the same locality and date as KIZ 056009–010 .

Referred specimen. ROM 41547 ( Figures 4 and 6 ), a male specimen (maturity unknown) found 8.8 km west of Simao , Yunnan Province, China (22° 46 ʹ 47.928 ʹ ’ N, 100° 54 ʹ 24.0372 ʹ ’ E; ~1270 metres above sea level) collected by Robert W. Murphy and Nikolai L. Orlov on 14 June 2002.

Diagnosis

A species of Calamaria distinguished from all other members of the genus found in mainland Southeast Asia by having the following combination of morphological characters: (1) rostral scale wider than high; (2) portion of rostral scale visible from above less than half the length of the prefrontal suture; (3) six scales and shields surrounding the paraparietal scale; (4) absence of a preocular scale; (5) four supralabials, with the second and third touching the eye; (6) five or six infralabials, the first pair separating the mental scale from the anterior chin shields; (7) 167–184 ventrals in males, 199 in female, three gular scales; (8) 15–20 subcaudals in males, 19 in female, all paired; (9) dorsal colour pattern variable, usually bluish-grey or olive-brown with indistinct dark brown longitudinal stripes across each dorsal scale row forming a network-like pattern, sometimes restricted to the flanks; (10) ventral surface red or yellow usually with dark brown margins on the ventral scales and a black midventral stripe under the tail, completely immaculate in some specimens; and (11) a light yellow nuchal collar posterior to the head usually present, absent in some specimens. A summary of diagnostic characters and comparisons is given below and in Tables 3–4 .

Description of the referred specimen

Male (maturity unknown) in good condition, with one incision at the tail base and another along the posterior portion of body. SVL 226 mm, TailL 20 mm, TotalL 246 mm, HeadL 7.4 mm (6.4 mm measured from the parietal tip), HeadW 4.0 mm, SnL 2.6 mm, SnW 2.0 mm, EyeD 1.0 mm, NarEye 1.5 mm, IOD 3.1 mm. Body height at midbody 3.5 mm, at tail base 3.3 mm; eye–mouth distance 0.8 mm; rostral scale width 0.9 mm, height 1.1 mm; prefrontal scale length 1.8 mm, suture 1.0 mm; frontal scale length 2.4 mm, width 1.9 mm; parietal scale length 3.3 mm, suture 1.8 mm. TailL/TotalL 0.081; HeadL/W 1.6; HeadL/SVL 2.83; SnL/HeadL 0.41; EyeD/SnL 0.38; NarEye/SnL 0.58; SnW/IOD 0.66; IOD/HW 0.76.

Body elongate and vermiform, round in cross section; tail thick, roughly equal in diameter to rest of body; posterior portion of tail slightly tapering, then abruptly tapering at the tip, which appears obtusely pointed in dorsal view (weakly acute), round in lateral view; head sub-oblong in dorsal view, indistinct from neck; snout blunt, weakly depressed posteriorly; nostrils small and elliptical; eyes small, round, diameter larger than eye– mouth distance; pupil indistinct, round; rostral scale triangular in frontal view, wider than high, portion visible from above roughly 4/5 the length of the prefrontal suture, suture bordering prefrontal and rostral scale deep-‘V’-shaped; prefrontal scales subhexagonal, shorter than frontal; frontal scale shield-shaped, hexagonal, 1.3× longer than wide, around 1.4× longer than parietal suture; posterior angle formed by the frontal/ parietal sutures producing the posterior vertex of the frontal right (~90°); parietals subhexagonal, longer than wide, longer than frontal; parietal suture 1.4× longer than prefrontal suture; anterior parietal angle formed by the sutures between the parietal/frontal and the suture between the supraocular/parietal broadly obtuse, pointing laterally (~127°); supraoculars subrectangular, width of frontal around 2.7× maximum width of supraoculars; paraparietal shaped like a temporal scale with 6/6 scales and shields in contact; postocular scale rectangular, not as high as eye diameter; preocular absent; nasal scale small, subrectangular, barely surrounding nostrils; supralabials 4/4, 1st and 2nd smallest, 1st in contact with nasal, 1st and 2nd in contact with prefrontal, 2nd and 3rd in contact with eye, 4th largest and rectangular; infralabials 5/5, 1st smallest and blocking mental from contacting upper genials, 1st–3rd in contact with upper genials; 3rd–4th in contact with lower genials, 5th largest; mental triangular, unremarkable; upper genial scales paired and rectangular, completely in contact; lower genials in contact anteriorly and separated at midsection by the first gular scale, posterior portion round-pointed; three gular scales before first ventral scale, all rhomboid.

Dorsal scale rows smooth, in 13–13–13 rows across entire body; dorsal scales reducing to six rows above the 3rd subcaudal scale, reducing to four scales above the 16th (third-tolast) subcaudal scale; ventrals 167; subcaudals 19, all paired; cloacal plate single; total body scales 187; subcaudal ratio 0.102; maxillary teeth 8/8, modified.

Colouration of the referred specimen in preservative

After formalin fixation and preservation in 70% ethanol for 18 years, the dorsum is greybrown and highly iridescent; margins of all dorsal scales dark brown with faint light brown vermiculations on the medial portion of most dorsal scales; dark margins of dorsal scales forming a weak network-like pattern; along flanks, three dark brown longitudinal stripes, lower two stripes 0.5–1.0 dorsal scale rows wide, separated from each other by 0.5 dorsal scale rows; first two stripes on flanks broader (one dorsal scales wide) than highest stripe (0.5 dorsal scale rows wide) along the anterior portion of body; highest stripe two dorsal scales above lower stripes, reduced to one dorsal scale row at midbody; medial portion between stripes filled with light white vermiculations; all longitudinal stripes fade posteriorly, except for one pair that continues onto the posterior portion of tail; dorsal portion of head dark brown with occasional light brown hueing along cephalic scales; nuchal collar whitish-tan, around one dorsal scale in width at vertebrum then widening in lateral view, originating at the third and fourth row of dorsal scales; supralabials and nasal tannish, fourth supralabial mostly white; flanks along nape also white, connecting to nuchal collar; eye blue, pupil greyish-blue; underside of head cream with grey-brown mottling scattered along mental, infralabials, upper genials and nuchal region of first dorsal scales; venter white, margins dark brown; underside of tail with small dark spotting along margins and dark brown midventral stripe starting from tail tip, breaking up near the start of the cloacal plate.

Description of the topotypic specimens and variation

Zhao et al. (1998) and Yang and Rao (2008) published descriptions of C. yunnanensis based on the same three topotypic specimens (2 males, 1 female). Although they originate from the type locality, the written descriptions of these specimens by these authors have slight differences from Chernov (1962) ’s original description and from ROM 41547. Zhao et al. (1998) indicated that the midventral stripe and nuchal collar in C. yunnanensis may be present or absent, while Yang and Rao (2008) did not note the presence of either feature. Photographs of these specimens from the KIZ collection allow me to clarify this issue ( Figure 5 ; Shuo Liu, pers. comm.) The official museum catalogue numbers for these specimens are different than those given in Yang and Rao (2008), but they can be associated with their specimen numbers based on scale counts and body measurements. In the single female specimen (KIZ 054176), the distinct nuchal collar and midventral stripe on the tail is absent. The dorsum is brown, becoming darker posteriorly near the tail, with indistinct longitudinal stripes along the edges of the dorsal scales forming a ‘net-like’ pattern. The venter is immaculate yellow, with the light pigment extending onto the first outer row of dorsal scales. Zhao et al. (1998) and Yang and Rao (2008) also provide conflicting data on the number of ventrals and subcaudals for this specimen, with the former reporting 198 ventrals and 19 subcaudals and the latter reporting 201 ventrals with 21 subcaudals. A re-count of the scales for this specimen indicates that it has 199 ventrals and 19 subcaudals, agreeing more with Zhao et al. (1998). This number is significantly higher than for the male specimens of C. yunnanensis (167–184), but sexual dimorphism in the number of scale counts is common in Calamaria , and most females in the genus have a higher number of ventrals than the males ( Inger and Marx 1965).

In the other specimens (KIZ 056009–010), both males, the midventral stripe is present on the tail and a nuchal collar is present in one of the specimens (KIZ 056010). The other specimen (KIZ 056009) is partially destroyed with only the midbody and tail remaining, so it is uncertain whether or not it had a nuchal collar. Both specimens also have some dark brown vermiculate-shaped spots present on the underside of the tail in addition to the midventral stripe (KIZ 056009–010). It is unknown whether or not the type specimen contained this characteristic, but a few small dark vermiculations are present on ROM 41547. Otherwise, the colouration of these three specimens agrees with Chernov (1962) ’s original description of C. yunnanensis and with ROM 41547, with the only differing characteristic being the presence of indistinct dark brown longitudinal stripes on the dorsum. Chernov (1962) did not note this feature in his description but stated that the margins of the dorsal scales were often dark brown and ‘continuous’, suggesting that there were indistinct stripes as described in these other topotypic specimens. Indeed, the striped pattern is barely visible on some the other topotypic specimens in the KIZ collection due to their state of preservation, and this artefact could have caused Chernov to miss this character when he was writing his description. Another characteristic shared by these specimens is the presence of dark brown margins along the ventral scales, which is shared with ROM 41547.

The scale counts for both specimens are identical to those given by Zhao et al. (1998) and Yang and Rao (2008), except KIZ 056009 has 20 subcaudal scales instead of 22 scales as reported by these authors. A fourth specimen (KIZ 056011), unreported in either study, was also found in the collection. It is an immature individual and its sex cannot be accurately determined, but it clearly possesses the same colour pattern characteristics as KIZ 056009–010 and ROM 41547. Overall, the colour polymorphism observed in these topotypic specimens agrees with the description provided by Zhao et al. (1998), while Yang and Rao (2008) ’s omission of these characteristics may have caused confusion in diagnosing the species.

Photographs of a live C. yunnanensis shown in Yang and Zheng (2018, fig. 4) and in Figure 1 offer some insight into the live colouration of this species. The specimen agrees with the colour pattern observed in KIZ 054176. However, the dorsum is predominately olive-brown, becoming dark grey-brown posteriorly, with well-defined dark brown longitudinal stripes across the body forming a network-like pattern on the dorsum. The venter in this specimen is a bright coral red, extending onto the lower flanks of the first two dorsal scale rows and on the labial region of the head and nostrils. A streak of red pigment forms a small marking posterior to the parietals but is too indistinct to be considered a nuchal collar, as it is nowhere near as pronounced as the markings present in other specimens. Red colouration may have been present on the ventral surface of other topotypic C. yunnanensis specimens and ROM 41547, but this pigment tends to fade quickly after preservation.

Distribution and natural history

So far, C . yunnanensis has been collected from three localities in south-central Yunnan Province, China ( Figure 7 ) . The type locality, Jingdong Autonomous County, is situated 1100–1200 metres above sea level, while the locality of ROM 41547 was at 1270 metres above sea level . The type specimen was found underneath a rock in a forested montane valley . The photographed individual in Yang and Zheng (2018) was located approximately 60 km north-west of the type locality in Nanjian Yi Autonomous County, Dali, Yunnan Province, China (24°48 ʹ 09.3” N, 100°32 ʹ 58.5” E; ~1700 metres above sea level) . It was found on 27 July 2011 at night between 17:00 and 18:00 UTC, attempting to climb across a rock along the road’s shoulder (Chung-Wei You, pers. comm) . The surrounding habitats in these localities include a mix of tropical montane deciduous forests near Simao, and montane evergreen broadleaf forests near Nanjing Yi and Jingdong Autonomous Counties . The climate in these regions is monsoon influenced and considered humid subtropical (Cwa) or subtropical highland (Cwb) according to the Köppen Classification ( Peel et al. 2007) . Besides this information, nothing else is known regarding its natural history, but given these observations, it is likely a nocturnal species . Similar to other species of Calamaria , it is presumed to be a fossorial species of snake that spends most of its life underground or below the forest floor, feeding on small soft-bodied invertebrates such as earthworms ( Inger and Marx 1965).

Conservation status

Calamaria yunnanensis has been recorded from two localities in southern Yunnan Province China based on a total of six to seven known specimens . The full extent of this species distribution in Yunnan Province is unknown . I recommend that C. yunnanensis be listed as ‘ Data Deficient’ following the IUCN’s Red List categories ( IUCN 2019).

Etymology

The species epithet ‘ yunnanensis ’ is a reference to the type locality situated in Yunnan Province, China . I recommend the English common name ‘ Yunnan reed snake’.

Figures

Figure 1. (a) Portrait of Soviet herpetologist Sergey A. Chernov, who would describe the type specimen of C. yunnanensis; (b) the original illustration of the holotype of C. yunnanensis (ZISP 17073) from Jingdong, Yunnan Province, China, from Chernov (1962), used with permission; (c) the left lateral view of the head of a referred specimen of C. yunnanensis (ROM 41547) from Simao, Yunnan Province, China; and (d) a photograph of a live C. yunnanensis from Nanjian Yi Autonomous County, Yunnan Province, China exhibiting a different colour pattern on the head compared to the original description. Photo of (a) from the Zoological Institute of the Russian Academy of Sciences archive published in Ananjeva and Doronin (2020), used with permission by Dr. Natalia J. Ananjeva; photo of (c) taken by Justin L. Lee; photo of (d) taken by Chung-Wei Logan You, used with permission.

Figure 4. Referred specimen of Calamaria yunnanensis (ROM 41547) with (a) dorsal and (b) ventral views of the body, along with (c) right lateral,(d) dorsal and (e) ventral views of the head.Scale bars: a, b = 10 mm; c–e = 5 mm. Photographs taken by Justin L. Lee.

Figure 5. Examples of Calamaria yunnanensis from the type locality: adult female (KIZ 054176), (a) dorsal and (b) ventral views; adult male (KIZ 056010), (c) dorsal and (d) ventral views; male (KIZ 056009), (e) dorsal view; and immature specimen, sex unknown (KIZ 056011), (f) dorsolateral view. Photographs taken by Shuo Liu, used with permission.

Figure 6. Lateral views of the tail tips of (a) Calamaria nebulosa sp. nov. holotype (FMNH 258666) and (b) Calamaria yunnanensis (ROM 41547). Scale bar: 10 mm. Photographs by Justin L. Lee.

Figure 7. Map showing the distribution of Calamaria nebulosa sp. nov. (red) and Calamaria yunnanensis (blue). Stars represent type localities. Map created using simplemappr.net.