Calamaria nebulosa, Lee, 2021

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 : 539-547

Calamaria nebulosa sp. nov.

Zoobank Registration: http://www.zoobank.org/ urn:lsid:zoobank.org:act:13AC3177-FFBD-4C12-9132-A9BA5ED7BB48

Calamaria yunnanensis : Stuart and Heatwole (2008: 98), Quah et al. (2019: 3 in part)

Calamaria cf. yunnanensis : Weinell et al. (2021: 3)

Holotype. FMNH 258666 (field tag: HKV 64382), an adult female ( Figures 3 and 6 ) collected dead on the road ( DOR) on the mountainous road to Udomxai [= Oudomxai] about 25 km from Phongsaly City , Phongsaly District, Phongsaly Province, Laos (21.483333°N, 102.2°E; ~1000 metres above sea level). Collected by Mr Bounthavy Phommachanh on 6 October 1999.

Diagnosis

A species of Calamaria distinguished from all other members of the genus from 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 approximately 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 infralabials, the first pair separating the mental scale from the anterior chin shields; (7) 179 ventrals and three gular scales; (8) 22 paired subcaudals; (9) dorsal colour pattern in preservative bluish-grey with five indistinct dark brown longitudinal stripes; (10) ventral surface of tail in preservative uniform yellow, immaculate; and (11) absence of a distinct white nuchal collar posterior to the head. A summary of diagnostic characters and comparisons is given below and in Tables 3–4 .

Description of the holotype

Adult female in good condition, with some original layers of scales sloughed away on the head and midbody, small incision at base of tail and at midbody. SVL 326 mm, TailL 28 mm, TotalL 354 mm; HeadL 8.8 mm (7.3 mm measured from the parietal tip); HeadW 5.6 mm; SnL 2.8 mm; SnW 2.1 mm; EyeD 1.3 mm; NarEye 2.0 mm; IOD 3.5 mm. Body height at midbody 5.6 mm, at tail base 4.6 mm; eye-–mouth distance 1.1 mm; rostral scale width 2.0 mm, height 1.6 mm; prefrontal scale length 2.3 mm, suture 1.8 mm; frontal scale length 2.7 mm, width 1.9 mm; parietal scale length 4.0 mm, suture 2.5 mm. TailL/TotalL 0.079; HeadL/W 1.58; HeadL/SVL 2.25; SnL/HeadL 0.32; EyeD/SnL 0.46; NarEye/SnL 0.71; SnW/IOD 0.60; IOD/HW 0.63.

Body elongate and vermiform, ellipsoid in cross section; tail thick, equal in diameter to rest of body anteriorly and medially; posterior portion of tail gradually tapering to the tip, which appears obtusely pointed in dorsal view, rounder in lateral view; head ovate in dorsal view, indistinct from neck; snout blunt, somewhat depressed posteriorly; nostrils small and elliptical; eyes small, round, diameter slightly larger than eye–mouth distance; pupil indistinct, round; rostral scale subtriangular in frontal view, wider than high, portion visible from above approximately 1/2 the length of the prefrontal suture, suture bordering prefrontal and rostral scale shallow-‘V’-shaped; prefrontal scales subhexagonal, shorter than frontal; frontal scale shield-shaped, subhexagonal, 1.4× longer than wide, around 1.1× 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, scale length 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 broad obtuse, pointing laterally (~130°); supraoculars subrectangular, width of frontal around 2.4× maximum width of supraoculars; paraparietal shaped like a temporal scale with 6/6 scales and shields in contact; postocular rectangular, not as high as eye diameter; preocular absent; nasal scale small, 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 truncate-tipped; three gular scales before first ventral scale, all rhomboid.

Table 3. (Continued).

Table 4. (Continued).

Morphological character C. nebulosa sp. nov. C. abramovi C. albiventer C. andersoni C. buchi C. concolor C. dominici C. gialaiensis C. ingeri C. lovii gimletii Morphological character C. strigiventris C. lovii ingermarxorum C. lumbricoidea C. thanhi C. pavimentata C. yunnanensis C. sangi C. schlegeli schlegeli C. septentrionalis

Portion of rostral scale visible from above greater than half with length of prefrontal suture (1) or less than or equal to to half its length (0) 1 0 1 1 0 0 1 1 0 Number of scales surrounding paraparietal 6 4–5 5–6 5–6 5–6 6 6 6–7 6 Prefrontal: longer than frontal scale (1) or smaller than/equal to frontal scale (0) 1 0 0 0 0 0 0 0 0 Preocular: present (1) or absent (0) 0 1 1 1 0–1 1 1 0 0 Mental touching (1) or separated from (0) anterior genials 1 1 0 1 0 0 0 0 0 Posterior genials meeting in midline (1), diverging or meeting only in anteriorly (0) 1 1 1 0 0–1 1 0 0 0 End of tail Blunt Sharp point Sharp point Obtuse point Blunt Round Abruptly to point Gradually to point Obtuse point Dorsal scales reducing to four rows above position of subcaudal anterior to tail tip 4th–5th subcaudal Last–11th subcaudal Last–13th subcaudal Last–3rd subcaudal 3rd–25th subcaudal Does not decrease Last–6th subcaudal Does not decrease 3rd-to-last subcaudal Maxillary teeth (modified = m) 8 (m) 9–11 (m) 8–9 (m) 9 (m) 9–10 (m) 8–9 (m) 9–11 (m) 9 (m) 8–9 (m) Ventrals 205 (M) 137–229 (F) 144–196 (M) 137–206 (F) 125–168 (M) 2 + 190 (?) 136–180 (F) 129–161 (M) 168–188 (F) 148–166 (M) 158–180 (F) 130–157 (M) 198 (F) 184 (M) 199 (F) 167–184 (M) Subcaudals 23 (M) 13–21 (F) 17–27 (M) 8–20 (F) 13–33 (M) 19 (?) 19–37 (F) 25–44 (M) 6–11 (F) 15–19 (M) 20–30 (F) 29–33 (M) 21 (F) 28 (M) 19 (F) 15–20 (M) Dorsum Bluish-grey Dark brown to black Brown Greyish brown Dark brown to black Dark brown to black Slate grey to grey-brown Dark blue to grey Blue-grey to olive-brown Venter Dark grey Yellow Yellow Yellow white or yellow Yellow Yellow and black Yellow Yellow or red Dorsal scales with light spots present (1) or absent (0) 0 0–1 0 0 0 1 0 0 1 Dorsum with light nuchal collar (1) or absent (0) 1 0 0–1 1 0 1 0 0 0–1 Tail with light rings: present (1) or absent (0) 0 0–1 0–1 0 0–1 1 0 1 0 Underside of tail with dark midventral stripe present (1) or absent (0) 0 0 0–1 1 0 1 1 0 0–1 TailL/TotalL ratio (given as %) 7.4 (M) 3.9–8.3 (F) 6.3–11.4 (M) 3.7–8.5 (F) 6.9–16.9 (M) 6.2 (?) 7.3–14.4 (F) 11.1–21.3 (M) 2.6–4.3 (F) 6.3–8.6 (M) 8.4–11.5 (F) 13.8–17.9 (M) 6.8 (F) 9.9 (M) 5.0 (F) 5.4–8.2 (M)

Dorsal scale rows smooth, in 13–13–13 rows across entire body; dorsal scales reducing to six rows above the 12th subcaudal scale, reducing to four scales above the last subcaudal scale; ventrals 179; subcaudals 22, all paired; cloacal plate single; total body scales 202; subcaudal ratio 0.109; maxillary teeth 9/9, modified.

Colouration of the holotype in preservative

After formalin fixation and preservation in 70% ethanol for 21 years, the dorsum is bluish-grey, exposed areas of skin where layers of scales have been removed are dark brown; margins of dorsal scales dark grey with faint light yellow vermiculations on scales; there are five indistinct dark brown longitudinal stripes starting at the nape, fading posteriorly towards the tail; these stripes are one dorsal scale row wide, separated from each other by 1–1.5 dorsal scale rows; first three rows of nape pale yellow, immaculate; top of head same colour as dorsum, hued olive-brown on top of head shields; eye blue, pupil grey-blue; bottom half of supralabials and rostral pale yellow; underside of head and rest of venter also pale yellow, margins of ventral scales immaculate with yellow pigment extending onto the first three dorsal scale rows on nape, reducing to two rows across the rest of the body bordered by outermost row of longitudinal stripes; underside of tail the same as rest of venter. Colour in life not recorded.

Comparisons

Calamaria nebulosa sp. nov. was compared to all other members of the genus inhabiting mainland Southeast Asia. Since C. nebulosa sp. nov. is known only from a single female, morphological data from male Calamaria specimens were excluded from the comparisons. Calamaria nebulosa sp. nov. is morphologically assigned to Calamaria by having an elongate, cylindrical body, absence of a loreal scale, four supralabials, five infralabials and 13 rows of iridescent dorsal scales throughout the body. Additional morphological features that distinguish C. nebulosa sp. nov. from its congeners can be found in Table 4 .

The absence of a preocular scale in Calamaria nebulosa sp. nov. distinguishes it from all congeners inhabiting mainland Southeast Asia (i.e. Calamaria abramovi Orlov, 2009 , Calamaria albiventer ( Gray, 1834) , Calamaria andersoni Yang and Zheng 2018 , Calamaria buchi Marx and Inger, 1955 , Calamaria concolor Orlov, Nguyen, Nguyen, Ananjeva and Ho, 2010 , Calamaria gialaiensis Ziegler, Sang and Nguyen, 2009 , Calamaria ingeri Grismer, Kaiser and Yaakob, 2004 , C. lumbricoidea , C. pavimentata , Calamaria sangi Nguyen, Sang and Ziegler, 2009 , C. septentrionalis and Calamaria strigiventris Poyarkov, Nguyen, Orlov and Vogel, 2019 ) except for Calamaria dominici Ziegler, Tran and Nguyen in Ziegler et al., 2019, Calamaria lovii gimletti Boulenger, 1905 , C. lovii ingermarxorum Darevsky and Orlov, 1992 , C. schlegeli schlegeli , C. thanhi Ziegler and Quyet, 2005 and C. yunnanensis , where the condition of the preocular is either absent or variable.

Among these taxa, C. nebulosa sp. nov. is distinguished from C. schlegeli schlegeli (the only species of Calamaria in the region where the preocular can be present or absent) by having the end of the tail tapering to an obtuse point (vs blunt point), dorsal scales reducing to four rows above the last subcaudal anterior to the tail tip (vs reducing above the 3rd–25th subcaudal), and by having a bluish-grey dorsum with longitudinal stripes (vs dorsum usually black with a reddish head or a yellow nuchal collar with no light vermiculations on dorsal scales); from C. dominici by having the mental separated from the anterior genials (vs mental in narrow contact with anterior genials), dorsal scales reducing to four rows above the last subcaudal anterior to the tail tip (vs reducing above the 5th–6th subcaudal), 179 ventrals and 22 subcaudals in female (vs 174 ventrals and 17–18 subcaudals in females), tail length 7.9% of total length in female (vs 6.0% of total length in females) and a bluish-grey dorsum with longitudinal stripes (vs dark blue dorsum covered with bright yellow spots); from C. lovii gimletti by having the posterior genials meeting only anteriorly (vs meeting at midline), the end of the tail tapering to an obtuse point (vs tapering to a blunt point), 179 ventrals and 22 subcaudals in female (vs 215–249 ventrals and 10–12 subcaudals in females) and a bluish-grey dorsum with longitudinal stripes (vs dorsal colour variable, but usually with a light nuchal collar, small yellow spots on the nape and tail and no light vermiculations on dorsal scales); from C. lovii ingermarxorum by having the portion of the rostral scale visible from above roughly equal to half the length of the prefrontal suture (vs greater than half the length of the prefrontal suture), the length of the prefrontal smaller than the frontal scale (vs longer than frontal), mental separated from the anterior genials (vs in contact with anterior genials), posterior genials meeting only anteriorly (vs meeting at midline), the end of the tail tapering to an obtuse point (vs tapering to a blunt point), dorsal scales reducing to four rows above the last subcaudal anterior to the tail tip (vs reducing above the 4th–5th subcaudal), 9 modified maxillary teeth (vs 8), and a bluish-grey dorsum with longitudinal stripes (vs dorsum blue-grey with a light nuchal collar and greyish venter); and from C. thanhi by having the end of tail tapering to an obtuse point (vs tapering gradually to a point), dorsal scales reducing to four rows above the last subcaudal anterior to the tail tip (vs not reducing to four rows), 179 ventrals and 22 subcaudals in female (vs 198 ventrals and 21 subcaudals in female) and by having a bluish-grey dorsum with longitudinal stripes (vs dorsum dark blue or grey with several light body and tail rings).

Most specimens of C. yunnanensis can be distinguished from C. nebulosa sp. nov. by having a distinct nuchal colour posterior to the head and a dark brown midventral stripe under the surface of the tail (vs nuchal collar and midventral stripe absent) and by having dark brown margins on each of the ventral scales (vs ventral scales immaculate). However, some specimens of C. yunnanensis do not share these colour pattern traits. In specimens where the colouration is difficult to interpret in preservative or is variable, C. nebulosa sp. nov. can be differentiated from C. yunnanensis by having 179 ventrals in female (vs 199), subcaudal/total body scale ratio of 10.9% in female (vs 8.7%), tail length approximately 7.9% of total length in female (vs 5.0%), dorsal scales reducing to six rows above the 12th subcaudal (vs 3rd to 5th subcaudal) and reducing to four rows above the last subcaudal (vs third-to-last subcaudal). All specimens of C. yunnanensis have narrow dark brown longitudinal stripes present on the margins of each dorsal scale row, occasionally restricted to the flanks in some specimens (vs five, wider dark brown longitudinal stripes, not present on every margin of each dorsal scale row), but these characters can be difficult to interpret on some specimens and should be treated with caution.

Distribution and natural history

The only known specimen was collected DOR on a mountainous road to the city of Udomaxi, Phongsaly Province, northern Laos ( Figure 7 ). The type locality is approximately 1000 metres above sea level, where the surrounding habitat is dominated by dry evergreen forests and tropical montane deciduous forests ( MacKinnon and MacKinnon 1986). The climate surrounding Phongsaly Province is monsoon influenced and humid subtropical (Cwa in the Köppen climate classification), with a rainy season starting in the spring around May and ending in the fall around October ( Peel et al. 2007; Geiser and Nagel 2013). Nothing else is known about the natural history of the new species. It is presumed to resemble other Calamaria in being an oviparous species 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 nebulosa sp. nov. is known from only a single specimen and has not been recorded since its discovery in 1999. The full extent of its distribution is unknown but the habitat around the type locality is relatively continuous across most of northern Laos, as well as adjacent Vietnam, northern Thailand, eastern Myanmar and southern China . It is likely that C. nebulosa sp. nov. also occurs in these countries, but until additional specimens are found, I recommend that this new species be listed as ‘ Data Deficient’ following the International Union for Conservation of Nature ( IUCN) Red List categories ( IUCN 2019) .

Etymology

The species epithet ‘ nebulosa ’ is the nominative form of the word ‘ nebulous ’, meaning ‘misty, foggy or cloudy’ in Latin, and is given in the feminine form to match the female genitive declension of the genus name Calamaria . The species name is an allusion to both the type locality of this snake, situated in the mountainous regions of Laos, and the generally clouded appearance of its dorsal ground colour in preservative. I recommend the English common name ‘Clouded reed snake’.

Figures

Figure 3. Holotype of Calamaria nebulosa sp. nov. (FMNH 258666) 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 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.

Tables

Table 4. Morphological comparisons between Calamaria nebulosa sp. nov. (FMNH 258666), Calamaria yunnanensis and all species of Calamaria known from mainland Southeast Asia (see Materials and methods for list of literature sources). Symbols used in this table include: (M) = male; (F) = female; (m) = modified maxillary teeth.

Morphological character	C. nebulosa sp. nov.	C. abramovi	C. albiventer	C. andersoni	C. buchi	C. concolor	C. dominici	C. gialaiensis	C. ingeri	C. lovii gimletii
Portion of rostral scale visible from above greater than half with length of prefrontal suture (1) or less than or equal to to half its length (0)	0	–	1	1	1	–	0	0	0	0
Number of scales surrounding paraparietal	6	6	5	6	5	5	6	5	6	6
Prefrontal: longer than frontal scale (1) or smaller than/equal to frontal scale (0)	0	0	0	0	0	1	0	0	1	0
Preocular: present (1) or absent (0)	0	1	1	1	1	1	0	1	1	0
Mental touching (1) or separated from (0) anterior genials	0	0	1	0	1	1	1	1	0	0
Posterior genials meeting in midline (1), diverging or meeting only in anteriorly (0)	0	0	1	0	1	1	0	0	1	1
End of tail	Obtuse point	Sharp point	Sharp point	Obtuse point	Obtuse point	Obtuse point	Obtuse point	Round	Blunt	Blunt
Dorsal scales reducing to four rows above position of subcaudal anterior to tail tip	Last subcaudal	Last subcaudal	5th–8th subcaudal	2nd-to-last subcaudal	3rd–4th subcaudal	Last subcaudal	5th–6th subcaudal	Last subcaudal	Last subcaudal	Last–5th subcaudal
Maxillary teeth (modified = m)	9 (m)	8 (m)	9 (m)	9 (m)	9 (m)	8 (m)	9 (m)	9 (m)	7 (m)	8–9 (m)
Ventrals	179 (F)	174 (F) 159 (M)	147–162 (F) 143–144 (M)	171 (M)	221–236 (F)	3 + 209 (M)	174 (F)	3 + 191 (M)	213–228 (F)	215–249 (F) 161–202 (M)
Subcaudals	22 (F)	20 (F) 26 (M)	15–19 (F) 21–22 (M)	23 (M)	13–14 (F)	19 (M)	17–18 (F)	23 (M)	11–10 (F)	10–12 (F) 14–20 (M)
Dorsum	Bluish-grey	Black	Brown	Brownish	Black	Brown	Black	Grey-brown	Dark brown	Dark brown
Venter	Yellow	Black and yellow	Red	Yellow	Yellow	Cream	Yellow and black	Yellow	Yellow	Yellow
Dorsal scales with light spots present (1) or absent (0)	1	1	1	1	1	0	0	0	0	0
Dorsum with light nuchal collar (1) or absent (0)	0	0	1	0	0	0	0	0	1	0–1
Tail with rings: present (1) or absent (0)	0	0	0	0	0	0	0	1	1	0–1
Underside of tail with dark midventral stripe present (1) or absent (0)	0	0	1	1	0	1	0	1	0	0
TailL/TotalL ratio (given as %)	7.9 (F)	7.1 (F) 13.3 (M)	4.7–8.8 (F) 8.8–9.3 (M)	9.2 (M)	3.9–4.1 (F)	7.3 (M)	6.0 (F)	8.8 (M)	3.5–4.2 (F)	3.0–3.7 (F) 6.2–8.4 (M)

(Continued)