Dixonius somchanhae Nguyen & Luu & Sitthivong & Ngo & Nguyen & Le & Ziegler 2021, sp. nov.
Creators: name: Nguyen, Thuong Huyen
name: Luu, Vinh Quang
name: Sitthivong, Saly
name: Ngo, Hanh Thi
name: Nguyen, Truong Quang
name: Le, Minh Duc
name: Ziegler, Thomas
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Gekkonidae
Dixonius
Dixonius somchanhae

description: Dixonius somchanhae sp. nov.
Figs. 2–5
Holotype: Adult male, VNUF R.2020.3 (Field no. VT03) in Huaysorn-Huaysua Village, Nasaithong District, Vientiane Capital (18 o 11.450’ N, 104 o 45.926’ E, at an elevation of 285 m a.s.l.), Laos, collected by V. Q. Luu, N. V. Ha and S. Sitthivong on 26 September 2016.
Paratypes. VNUF R.2020.1 (Field no. VT01), adult male, and VNUF R.2020.2 (Field no. VT02), adult m a le; the same data as given for the holotype. VNUF R.2020.4 (Field no. VT02-14), adult female, and VNUF R.2020.5 (Field no. VT03-14), adult female, collected by V.Q. Luu and T. Calame in June 2014.
Diagnosis. A species of the genus Dixonius, characterized by a combination of the following characters: maximum SVL 47.1 mm; 19–21 longitudinal rows of dorsal tubercles at midbody; 23–26 longitudinal rows of ventrals across the abdomen; 7 or 8 supralabials, 6 in mid-orbital position; 5 or 6 infralabials; 5 or 6 precloacal pores in males, femoral pores lacking; precloacal and femoral pores absent in females; a canthal stripe running from rostrum through the eye and terminating at back of head; uniformly brown dorsum.
Description of the holotype. Adult male, SVL 43.8 mm with dorsolaterally flattened body, TaL 62.7 mm, trunk length 20.5 mm. Head longer than wide, depressed, distinct from neck. Head length 12.2 mm, head width 8.5 mm, eye of moderate size 3.4 mm, ear-opening round (EL 1.6 mm), snout-eye length 5.1 mm, internarial distance 1.3 mm.
Rostral very large, wider than high (width 1.9 mm, height 1.4 mm), with distinct suture; supralabials 7/7 (6 in midorbital position); nostril in contact with rostral, first supralabial, supranasal, and two nasals posteriorly on each side; supranasals in broad contact with each other; without intersupranasals; snout flat, covered with granular scales; pupil vertical; ear opening round, approximately one half of the eye diameter, without bordering enlarged scales; infralabials 5/5, decreasing gradually in size; mental triangular, wider than high (width 2.0 mm, height 1.6 mm); two pairs of enlarged postmentals, first pair very large and in contact with each other, second pair about one third size of first, in contact with the first and second infralabials and separated from each other by seven gular scales; dorsal tubercle rows at midbody 20, keeled, separated from each other by one smaller scale, keeled or at least almost conical shaped; ventral scales larger than dorsal scales, in 24 rows at midbody; dorsal surface of fore- and hind limbs covered by feebly keeled scales, area around limb insertions covered with small granular scales; paravertebral scales (number of scales in a paravertebral row from first scale posterior to parietal scale to last scale at the level of cloaca) 35; paravertebral scales in a row between limb insertions 21; lamellae on fourth toe 14; precloacal pores 6, in an angular series; tail covered by keeled scales, in different sizes; subcaudals 56, enlarged and undivided.
Coloration in life. Dorsum of the holotype brown in life with irregular dark marks (Fig. 2); head with dark blotches; a light brown canthal stripe running from rostrum through eyes, ending at back of head; light spots irregularly arranged from head to tail; ventral surface light beige to uniformly whitish as the belly and the throat; supralabials grey with dark grey spots; upper surface of toes uniformly light grey with dark blotches; dorsal surface of the tail light brownish-grey with cream lines.
In preservative, dorsal head, back and dorsal surface of tail brownish grey with irregular dark brown blotches; coloration on dorsal surface of fore- and hindlimbs grey brown. Canthal stripe dark brown, running from rostrum through eyes, stretching behind orbit to back of head. Round white spots arranged in two irregular rows extend from back of head along body and tail.
Sexual dimorphism. Morphologically, paratypes corresponded well with the holotype, except for the absence of precloacal pores in females (Table 2).
Comparisons. The new species from Vientiane Capital, Laos can be distinguished from all known Dixonius species as follows: from D. taoi from Vietnam by having more dorsal tubercle rows (19–21 versus 11–12), more ventral scale rows at midbody (23–26 versus 21–23), and different color pattern on head and tail (light spots irregular arranged from head to tail versus four to seven round yellowish spots, arranged in one or two irregular rows from back of head onwards and continuing along tail); from D. minhlei from Vietnam by having more dorsal tubercle rows (19–21 versus 14–15), fewer precloacal pores in males (5–6 versus 7–8), and more ventral scale rows at midbody (23–26 versus 20–23); from D. siamensis by its smaller size (maximum SVL 47.1 versus 57 mm), having more dorsal tubercle rows (19–21 versus 10–14), and generally fewer precloacal pores in males (5–6 versus 6–7); from D. aaronbaueri by having more ventral scale rows at midbody (23–26 versus 18–19), more dorsal tubercle rows (19–21 versus 11), and fewer paravertebral scales in a row between limb insertions (PV’ 19–27 versus 29– 32); from D. dulayaphitakorum by having more ventral scale rows at mid-body (23–26 versus 22), fewer dorsal tubercle rows (19–21 versus 22), fewer interorbital scale (7–8 versus 9–10), and fewer infralabials (5–6 versus 7); from D. pawangkhananti by having more ventral scale rows at mid-body (23–26 versus 16), more dorsal tubercle rows (19–21 versus 16), and more paravertebral scales from first scale posterior to parietal scale to last scale at the level of cloaca (PV 35–40 versus 30–32); from D. hangseesom by having more dorsal tubercle rows at midbody (19–21 versus 12–14), more paravertebral scales from first scale posterior to parietal scale to last scale at the level of cloaca (PV 35–40 versus 26), and fewer precloacal pores in males (5–6 versus 7–8); from D. melanostictus by having more ventral scale rows at midbody (23–26 versus 22), more dorsal tubercle rows (19–21 versus 10–11), more paravertebral scales in a row between limb insertions (PV’ 19–27 versus 10–11), and fewer precloacal pores in males (5–6 versus 9); from D. kaweesaki by having more dorsal tubercle rows (19–21 versus 12–13), fewer precloacal pores in males (5–6 versus 9–11), different canthal stripe (a light brown canthal stripe running from rostrum through eyes, ending at back of head versus a black canthal stripe running through the eye, joining the upper part of the flanks), and coloration of tail light brownish-grey (versus light orange); from D. vietnamensis by its larger size (maximum SVL 47.1 versus 40.8 mm), having more dorsal tubercle rows at midbody (19–21 versus 16), and more supralabials (7–8 versus 5–6); from D. lao by its smaller size (maximum SVL 47.1 versus 55.4 mm), fewer infralabials (5–6 versus 7–8), and fewer precloacal pores in males (5–6 versus 8). For further distinguishing characters see Table 3.
Distribution. Dixonius somchanhae sp. nov. is currently known only from the type locality in Huaysorn- Huaysua Village, Vientiane Capital, Laos (Fig. 6).
Natural history notes. The type series was found at night, between 19h00 and 22h00, on the rocks of sandstone area (Fig. 7). The surrounding habitat was disturbed secondary forest of small hardwoods and shrubs.
Etymology. The new Dixonius somchanhae species is named after Associate Professor Dr. Somchanh Bounphanmy, from the National University of Laos, in recognition of her support of our biodiversity research in Laos.
description: Published as part of Nguyen, Thuong Huyen, Luu, Vinh Quang, Sitthivong, Saly, Ngo, Hanh Thi, Nguyen, Truong Quang, Le, Minh Duc & Ziegler, Thomas, 2021, A new species of Dixonius (Squamata: Gekkonidae) from Vientiane Capital, Laos, pp. 351-362 in Zootaxa 4965 (2) on pages 354-360, DOI: 10.11646/zootaxa.4965.2.8, http://zenodo.org/record/4750274