Achalinus tranganensis Luu & Ziegler & Ha & Lo & Hoang & Ngo & Le & Tran & Nguyen 2020, sp. nov.
Creators: name: Luu, Vinh Quang
name: Ziegler, Thomas
name: Ha, Nghia Van
name: Lo, Oanh Van
name: Hoang, Tuoi Thi
name: Ngo, Hanh Thi
name: Le, Minh Duc
name: Tran, Dung Hoang
name: Nguyen, Truong Quang
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Xenodermatidae
Achalinus
Achalinus tranganensis

description: Achalinus tranganensis sp. nov.
Figs. 2, 3
Holotype. VNUF R.2018.21 (field number TA.18.21), adult female, from limestone forest (20°15.266’N, 105°53.677’E, 9 m a.s.l.), near Tran Temple, Trang An Landscape Complex, Ninh Binh Province, northern Vietnam, collected by V. Q. Luu, O. V. Lo, N. T. Nguyen on 31 May 2018.
Diagnosis. Achalinus tranganensis sp. nov is characterized by the following combination of morphological characters: 1) maxillary teeth 29; 2) suture between the internasals distinctly longer than that between the prefrontals; 3) loreal distinctly wider than high, extending from the nasal to the eye; 4) dorsal scales in 25–23–23 rows, keeled; 5) two pairs of prefrontals; 6) supralabials six; 7) infralabials six; 8) temporals 2+3, the two anterior temporals in contact with eye; 9) ventrals 171; 10) subcaudals 73+, entire; 11) cloacal entire; 12) dorsum in preservative reddish to greyish brown above; 13) the lower part of head side and chin region somewhat paler than remaining head; 14) venter greyish cream, with the anterior region of each ventral and subcaudal somewhat darker.
Description of the holotype. Total length 448 mm (SVL 334 mm, TailL 114 mm); tail long, tail tip lost, tail length/ total length ratio 0.25; body slender, cylindrical; head length 9.9 mm; head slightly distinct from neck, dorsally covered with large shields; eye small, with vertically subelliptic pupil; left maxilla with 29 equally sized, curved teeth.
Rostral small, triangular, not visible from above; suture between internasals (2.3 mm) longer than that between prefrontals (1.6 mm); nostril in anterior part of nasal; frontal heptagonal, heart-shaped, slightly broader than long, pointed backwards, much shorter than parietals; parietal bordered behind by an elongated nuchal, nuchals separated from each other by three small, elongated scales; one loreal, distinctly longer than high, extending from nasal to eye; medial pair of prefrontals elongated, in broad contact with larger lateral prefrontal; lateral prefrontals in contact with nasal, internasal, medial prefrontal, frontal, supraocular, and loreal; one supraocular; two anterior temporals, both touching eye; two large posterior temporals (a minute scale present between upper anterior and posterior temporals on right); supralabials six, first smallest, fourth and fifth in contact with eye, sixth longest; one curved rectangle mental; six infralabials, first pair in contact with each other, first pair of chin shields larger than posterior, in contact with first three infralabials; posterior pair of chin shields smaller, in contact with third and fourth infralabials.
Dorsal scales elliptical, keeled from the neck region posteriorly, in 25-23-23 rows; ventrals 171 (no preventrals), approximately 3 times wider than long, laterally rounded; subcaudals 73+, unpaired; cloacal entire.
Colouration in preservative. Reddish to greyish brown above with weakly iridescent colouration in all scales; lower sides of head somewhat paler; venter greyish cream, with anterior region of the ventrals and subcaudals somewhat darker; underside of the tail somewhat darker than belly and the chin region somewhat paler than remaining head (Fig. 4).
Colouration in life. Dorsum iridescent reddish to greyish brown; underside of head light brown; venter greyish cream; under tail dark brown.
Comparisons. The condition of the prefrontals being arranged in two pairs is unique in Achalinus and thus distinguishes the new species from all other congeners and thus is not repeated in the detailed comparisons in the following. At first glance, Achalinus tranganensis sp. nov. resembles A. juliani in color pattern and dorsal scalerow formula. However, A. tranganensis can be distinguished from A. juliani by having fewer ventrals in the female (171 versus 179); from A. ater by having more anterior temporals (3 versus 2), more dorsal scale rows anteriorly (25 versus 23 or 21), and more subcaudals (73+ versus 47–70); from A. emilyae by having more infralabials (6 ver-sus 5), more posterior temporals (3 versus 2), more dorsal scale rows anteriorly (25 versus 23), more ventrals (171 versus 157–161), and more subcaudals (73+ versus 63); from A. formosanus by having more maxillary teeth (29 versus 14–17), the internasal suture distinctly longer than prefrontal suture (versus internasal suture almost as long as prefrontal suture), the loreal unfused with prefrontal (versus fused), fewer dorsal scale rows (25–23–23 versus 25–29– 25–27–25), more posterior temporals (3 versus 2), and lacking a black mid-dorsal line; from A. jinggangensis Zong & Ma, 1983 by having more maxillary teeth (29 versus 22), loreal unfused with prefrontal (versus fused), more posterior temporals (3 versus 2), more ventrals (171 versus 156–164), and more subcaudals (73+ versus 51–64); from A. hainanus Huang, 1975 by having more infralabials (6 versus 5), more temporals (2+3 versus 1+2), more dorsal scale rows anteriorly (25 versus 23), more ventrals (171 versus 165–168), and more subcaudals (73+ versus 67–69); from A. meiguensis by having more maxillary teeth (29 versus 17), more dorsal scale rows anteriorly and posteriorly (25 versus 21 or 23; 23 versus 19, respectively), and more subcaudals (73+ versus 39–62); from A. niger by having the internasal suture being distinctly longer than that between the prefrontals (versus almost as long as or shorter), fewer midbody scale rows (23 versus 25), more subcaudals in females (73 versus 52–58), and keeled dorsal scales (versus smooth on anterior part of body); from A. pingbianensis by having the loreal unfused with prefrontal (versus fused), more dorsal scale rows anteriorly (25 versus 23), more ventrals (171 versus 164+2), and more subcaudals (73+ versus 56); from A. rufescens by having more infralabials (6 versus 5), more posterior temporals (3 versus 2), more ventrals in females (171 versus 148–158), and more subcaudals (73+ versus 54–61); from A. spinalis by having more maxillary teeth (29 versus 16–20), the internasal suture being distinctly longer than that between the prefrontals (versus as long as or shorter), more posterior temporals (3 versus 2), more dorsal scale rows anteriorly (25 versus 21–24), and more subcaudals (73 versus 39–67); from Achalinus timi by having the loreal unfused with prefrontal (versus fused), more posterior temporals (3 versus 2), and fewer scale rows at midbody (23 versus 25); from A. werneri by the internasal suture being distinctly longer than that between the prefrontals (versus almost as long as), having more posterior temporals (3 versus 2), and by lacking a black mid-dorsal line; from A. yunkaiensis by having more maxillary teeth (29 versus 20–22), the internasal suture being distinctly longer than that between the prefrontals (versus as long as), more posterior temporals (3 versus 1), more dorsal scale rows anteriorly (25 versus 23), more ventrals (171 versus 151–162), and more subcaudals (73+ versus 38–56).
Distribution. Achalinus tranganensis sp. nov. is currently known only from the type locality in the Trang An
Landscape Complex, Ninh Binh Province, Vietnam (Fig. 4).
Etymology: We name this species after its type locality, the Trang An Landscape Complex, where the new Achalinus was discovered and propose the following common names: Trang An Burrowing Snake (English), Rắn xe điếu tràng an (Vietnamese).
Natural history. The holotype was found at 2045 h, while crawling on a forest path under dry leaves, at an elevation of 9 m a.s.l. The surrounding habitat is secondary karst forest (Fig. 5). The humidity at the time of collection was approximately 78%, and the air temperature was 29 oC. Other amphibians and reptiles were observed and collected in the area such as Theloderma annae Nguyen, Pham, Nguyen, Ngo, and Ziegler; Sylvirana guentheri (Boulenger), Lycodon futsingensis (Pope), L. subcinctus Boie, Oligodon chinensis (Günther).
description: Published as part of Luu, Vinh Quang, Ziegler, Thomas, Ha, Nghia Van, Lo, Oanh Van, Hoang, Tuoi Thi, Ngo, Hanh Thi, Le, Minh Duc, Tran, Dung Hoang & Nguyen, Truong Quang, 2020, A new species of Achalinus (Squamata: Xenodermidae) from Trang An Landscape Complex, Ninh Binh Province, Vietnam, pp. 174-184 in Zootaxa 4877 (1) on pages 177-180, DOI: 10.11646/zootaxa.4877.1.8, http://zenodo.org/record/4572461