Dixonius minhlei Ziegler, Botov, Nguyen, Bauer, Brennan, Ngo & Nguyen, 2016, sp. nov.
Creators: name: Ziegler, Thomas
name: Botov, Andreas
name: Nguyen, Tao Thien
name: Bauer, Aaron M.
name: Brennan, Ian G.
name: Ngo, Hanh Thi
name: Nguyen, Truong Quang
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Gekkonidae
Dixonius
Dixonius minhlei

description: Dixonius minhlei sp. nov.
Holotype (Figs. 3–5): IEBR A.0802 (male) collected between 28th and 29th of December 2007 by Tao Thien Nguyen and Cuc Thu Ho in Vinh Cuu Nature Reserve, Dong Nai Province, Southern Vietnam (11°22'40"N, 107°03'37"E, 70 m a.s.l. elevation).
Paratypes (Figs. 5–6): IEBR A.0801 (female), VNMN R.2016.1 (female), VNMN R.2016.2 (female), ZFMK 97745 (female), and ZFMK 97746 (male), same data as for the holotype.
Diagnosis. A small gecko with up to 47.5 mm SVL; 7–9 supralabials; 14–15 rows of keeled tubercles on dorsum; 20–23 ventral scale rows; 7 or 8 precloacal pores in males; a canthal stripe running from rostrum through the eye and terminating at back of head; lateral second pair of postmentals maximum one quarter the size of first pair; dorsum olive gray with more or less discernible brownish olive blotches.
); minimum and maximum measurements do only refer to adult individuals.
IEBR VNMN ZFMK IEBR VNMN ZFMK 97748 IEBR R.2016.4 ZFMK 97749 Min Max ZFMK 87273 R.2016.3 R.2016.3 97747 R.2016.1 R.2016.4
male male male female female female female juvenile female juvenile female
juvenile
39.0 39.6 34.1 43.5 43.7 45.2 31.2 29.2 39.0 43.7 42 partly 48.1 43.9 - broken - 38.5 30.7 48.1 49 regenerated
2.2 3.8 3.4 - - - 2.6 1.9 1.9 3.8 3.4 6.5 7.8 4.7 7.6 8.6 10.3 5.2 4.8 4.7 10.3 8.3 6.9 7.2 6.2 7.6 7.7 8.5 5.7 5.2 6.2 8.5 6.9 6.8 7.0 5.7 6.9 7.7 8.2 5.8 4.8 5.7 8.2 6.5 4.2 4.7 4.1 4.7 4.7 5.7 3.7 3.1 4.1 5.7 4.4 1.1 0.8 0.9 1.0 1.1 1.3 0.9 0.9 0.8 1.3 1.2 2.8 2.5 2.3 2.7 2.8 2.9 2.4 2.5 2.3 2.9 2.9 2.9 3.4 2.7 3.1 3.4 3.8 2.4 2.1 2.7 3.8 3.2 3.9 4.6 3.6 4.5 4.7 5.4 3.4 2.9 3.6 5.4 4.0 3.1 3.3 2.5 2.7 3.6 4.3 2.4 2.3 2.5 4.3 3.0 1.1 1.3 1.2 1.3 1.3 1.5 1.0 1.0 1.1 1.3 1.2 1.6 1.7 1.3 1.6 1.8 2.7 1.2 1.2 1.3 2.7 1.5
r 4.7 5.2 4.2 5.0 5.5 5.5 3.1 3.1 4.7 5.5 4.7
r 6.5 6.5 5.9 6.2 6.3 6.6 4.8 4.9 6.2 6.6 5.6
r 14.8 16.6 12.3 19.2 18.2 19.2 11.9 11.1 14.8 19.2 17.2
/ED 0.39 0.32 0.39 0.37 0.39 0.44 0.38 0.36 0.32 0.44 0.35
r/l 8/8 7/8 8/7 7/7 8/7 8/7 8/8 7/7 7 8 7
r/l 6/6 6/6 6/6 6/6 7/7 6/6 7/7 6/7 6 7 6 6/5 5/6 6/5 6/5 6/6 6/6 6/6 6/5 5 6 5/ 6 10 9 10 8 9 8 7 8 7 10 7 25 23 24 22 25 23 25 26 22 26 29 19 19 15 18 20 20 21 19 15 21 20 15 15 13 16 15 17 16 17 13 17 14
r/l 12/15 14 /13 14/13 14/13 13/13 14/14 13/12 13 / 14 12 15 17/ 16 6 5 7 - - - - - 5 7 -
canthal stripe + + + + + + + + + Taxon A
Dixonius aaronbaueri ZFMK 87274 A 0 B
Dixonius cf. siamensis VU 0 0 23 B 0.1588 0.0000 C
Dixonius cf. vietnamensis ZFMK 87273 C 0.1719 0.1331 0.0000 D
Dixonius melanostictus VU 0 0 22 D 0.1583 0.1066 0.1291 0.0000 E
Dixonius siamensis LLG 7328 E 0.1617 0.1271 0.1306 0.1274 0.0000 F
Dixonius siamensis LLG 7378 F 0.1603 0.1263 0.1306 0.1274 0.0042 0.0000 G
Dixonius vietnamensis ZFMK 97747 G 0.1712 0.1304 0.0521 0.1237 0.1203 0.1194 0.0000 H
Dixonius vietnamensis IEBR R. 2016.3 H 0.1713 0.1305 0.0522 0.1238 0.1204 0.1195 0.0000 0.0000 I Dixonius vietnamensis VNMN R. 2016.3 I 0.1722 0.1296 0.0530 0.1247 0.1212 0.1204 0.0008 0.0008 0.0000 J Dixonius vietnamensis VNMN R. 2016.4 J 0.1713 0.1305 0.0522 0.1238 0.1204 0.1195 0.0000 0.0000 0.0008 0.0000 K Dixonius taoi CAS 257300 K 0.1616 0.1240 0.0797 0.1184 0.1215 0.1208 0.0546 0.0547 0.0555 0.0547 0.0000 L Dixonius taoi IEBRA 2014 26 L 0.1664 0.1281 0.0867 0.1222 0.1267 0.1260 0.0622 0.0622 0.0631 0.0622 0.0065 0.0000 M Dixonius taoi IEBRA 2014 27 M 0.1592 0.1393 0.1039 0.1201 0.1433 0.1417 0.0573 0.0574 0.0574 0.0574 0.0145 0.0162 0.0000 N Dixonius taoi ZFMK 96680 N 0.1637 0.1280 0.0829 0.1200 0.1230 0.1223 0.0588 0.0589 0.0597 0.0589 0.0050 0.0093 0.0145 0.0000 O Dixonius sp.FMNH 263003 O 0.2064 0.1737 0.1912 0.1754 0.1583 0.1583 0.1785 0.1786 0.1794 0.1786 0.1712 0.1759 0.1223 0.1725 0.0000 P Dixonius minhlei sp. nov. ZFMK 97745 P 0.1601 0.1205 0.1538 0.1288 0.1078 0.1078 0.1371 0.1372 0.1380 0.1372 0.1323 0.1374 0.1254 0.1345 0.1284 0.0000 Q Dixonius sp.LSUHC 9466 Q 0.1244 0.0446 0.0994 0.0801 0.0884 0.0877 0.0816 0.0816 0.0808 0.0816 0.0825 0.0850 0.1142 0.0843 0.1316 0.0826 0 Description of the holotype. Adult male, snout-vent length 43.9 mm, body dorsolaterally flattened, tail length 53.2 mm (tail regenerated), trunk length 18.7 mm. Head almost as long as wide, depressed, distinct from slender neck. Head length 7.3 mm, head width 7.7 mm, eye of moderate size 2.7 mm, ear opening oblique (EL 1.5 mm), naris-eye length 3.7 mm, snout-eye length 5.0 mm, internarial distance 1.6 mm.
Rostral very large, wider (1.8 mm) than high (1.2 mm), with a distinct suture; supralabials 8 (sixth in midorbital position), smaller in subocular rictus; nostril in contact with rostral, first supralabial, supranasal, and two nasals posteriorly on each side; supranasals in contact anteriorly; internasals absent; snout flat, covered with granular scales; pupil vertical; ear opening oblique, oval, approximately one half of the eye diameter, without bordering enlarged scales; mental triangular, wider (2.2 mm) than high (1.7 mm); infralabials 6 on both sides, decreasing gradually in size; mental triangular, wider (2.2 mm) than high (1.7 mm); two pairs of enlarged postmentals, first pair very large and in narrow contact, second pair about less than one quarter the size of first, in contact with first and second infralabials and separated from each other by four gular scales; 12 keeled dorsal scale rows at midbody separated from one another by one or two smaller scales which are keeled or at least conical shaped; three to four rows of small scales along vertebrae; ventral scales larger than dorsal scales, in 22 rows at midbody, with distinct posterior serration; dorsal surface of fore- and hindlimbs covered with shallowly-keeled scales, area around limb insertions covered with small granular scales; 14 lamellae on fourth toe; no femoral pores; 7 precloacal pores in an angular series; pore bearing scales not enlarged; no precloacal depression; caudal scales keeled and covered with scales of different sizes, like on dorsum; 61 enlarged and undivided subcaudals on regenerated tail.
Dorsum olive gray in life, with round brownish olive blotches. A stripe of the same colour running from rostrum through eyes and ending at back of head. Dorsum of head with blotches of same colour. Dorsum and dorsal part of original tail covered with brownish olive blotches. Two specimens with a very pale, almost indiscernible pattern. Venter cream and regenerated tail without blotches. In preservative, dorsum light brown with dark greybrown blotches on head and body; colouration of tail and on dorsal surface of fore- and hindlimbs similar, but with less contrast.
Variation of paratypes: Blotches on head, dorsum and tail may appear very pale or almost absent in some individuals (Figs. 5–6). Variation in scalation is shown in Table 6.
Comparisons. Dixonius minhlei sp. nov. differs from all known Dixonius as follows: from D. aaronbaueri by having more ventral scale rows at midbody (20–23 versus 18–19 in D. aaronbaueri); more dorsal tubercle rows (14–15 versus 11 in D. aaronbaueri), more precloacal pores in males (7–8 versus 5 in D. aaronbaueri) and different color pattern (olive gray ground color on dorsum, with more or less discernible brownish olive blotches versus an unpatterned dorsum in D. aaronbaueri); from D. hangseesom by having fewer ventral scale rows at midbody (20–23 vs 22–26 in D. hangseesom); more dorsal tubercle rows (14–15 versus 12–14 in D. hangseesom) and coloration of tail same as the dorsum (versus orange tail in D. hangseesom); from D. melanostictus by having more dorsal tubercle rows (14–15 versus 10–11 in D. melanostictus); fewer precloacal pores (7–8 versus 9 in D. melanostictus), and canthal stripe continues behind orbit to back of head (versus canthal stripe extending along flanks in D. melanostictus); from D. siamensis in smaller size (47.5 mm max. SVL versus 57 mm in D. siamensis), more precloacal pores (7–8 versus 6–7 in D. siamensis) and in having a distinct canthal stripe (versus absence of canthal stripe in D. siamensis); from D. taoi by having more precloacal pores (7–8 versus 5–6 in D. taoi) and different dorsal pattern (dorsum olive gray with more or less discernible round brownish olive blotches versus presence of one or two irregular rows of yellowish marks running from head along flanks in D. taoi); from D. vietnamensis by having more precloacal pores (7–8 versus 5–7 in D. vietnamensis) and in dorsal head and body pattern (blotches on head and dorsum round, more or less discernible vs. dark transversal bands on the occiput and irregular blotches or reticulation on dorsum in D. vietnamensis).
Etymology. The new species is named after our friend and colleague Dr. Minh D. Le from the Faculty of Environmental Sciences, Hanoi University of Science, Vietnam National University, Hanoi, for his continuous and significant contributions towards a better understanding of the diversity and phylogenetic relationships of species from Vietnam and surrounding countries.
Distribution. Dixonius minhlei sp. nov. currently is only known from the type locality (Fig. 7). Natural history. The type series of Dixonius minhlei sp. nov. was collected at night, between 19:00 and 23:00, on the ground of the evergreen forest (Fig. 8). Further reptile species observed at the type locality were Acanthosaura lepidogaster, Calotes emma, and Cyrtodactylus cattienensis.
description: Published as part of Ziegler, Thomas, Botov, Andreas, Nguyen, Tao Thien, Bauer, Aaron M., Brennan, Ian G., Ngo, Hanh Thi & Nguyen, Truong Quang, 2016, First molecular verification of Dixonius vietnamensis Das, 2004 (Squamata: Gekkonidae) with the description of a new species from Vinh Cuu Nature Reserve, Dong Nai Province, Vietnam, pp. 553-566 in Zootaxa 4136 (3) on pages 556-562, DOI: 10.11646/zootaxa.4136.3.7, http://zenodo.org/record/260618