Asthenodipsas jamilinaisi, Quah & Grismer & Lim & Anuar & Imbun, 2019

Quah, Evan S. H., Grismer, L. Lee, Lim, Kelvin K. P., Anuar, M. S. Shahrul & Imbun, Paul Y., 2019, A taxonomic reappraisal of the Smooth Slug Snake Asthenodipsas laevis (Boie, 1827) (Squamata: Pareidae) in Borneo with the description of two new species, Zootaxa 4646 (3), pp. 501-526 : 508-515

Asthenodipsas jamilinaisi sp. nov.

Sabah Mountain Slender Slug Snake

Fig. 4 & 5 .

urn:lsid:zoobank.org:act:FE0ABCEE-6DD3-449E-A828-057CFB16639A

Amblycephalus laevis (in part): Boulenger 1896: 441 & 442; de Rooij 1917: 276.

Asthenodipsas laevis (in part): Das 2010: 344; Stuebing et al. 2014: 82.

Asthenodipsas vertebralis (in part): Stuebing et al. 2014: 82.

Internatus laevis (in part): Malkmus et al. 2002: 343.

Pareas laevis: Stuebing 1991: 330 & 331 (in part); Stuebing & Inger 1999: 87 (in part); Haile 1958: 766 (in part).

Pareas vertebralis (in part): Stuebing & Inger 1999: 87.

Holotype. Adult male, SP 04076 collected by Paul Yambun Imbun and other unspecified members of Sabah Parks on 14 May 1991 from Mount Trusmadi , Tambunan, Sabah, East Malaysia (estimated: N 5.552776, E 116.516667, 2612 m a.s.l.).

Paratypes. Juvenile male ( ZRC 2.2742 ) collected by F.N. Chasen and H.M. Pendlebury in May 1929 from Marei Parei , Mount Kinabalu, Sabah, East Malaysia (estimated: N 6.080644, E 116.519022, 1668 m a.s.l.) .

Diagnosis. Morphological examination of the type series determined their placement in the genus Asthenodipsas owing to their possession of smooth dorsal scales; absence of preoculars and suboculars; one or more supralabials in contact with the eye; a single anterior inframaxillary, followed by two or three pairs of inframaxillaries which are wider than long ( Grossmann & Tillack 2003)—character states that diagnose Asthenodipsas from other genera of the family Pareidae . Asthenodipsas jamilinaisi sp. nov. can be differentiated from its congeners by the following combination of characters: a maximum SVL of 378 mm; 15/15/15 dorsal scale rows; 173–175 ventrals (males); 52–53 subcaudal scales (male); postoculars; 1–2(+0–1)+2 temporals; 6–7 supralabials, 3 rd & 4 th touching the eye; 5–6 infralabials, 3 rd pair in contact; a sharp vertebral keel; dorsum of adults dark-brown with 44–48 indistinct dark bands that are more prominent on the lower dorsal rows along the flanks and extend onto the corners of the ventrals; chin & throat dark-brown; ventrals cream to light-yellow; and iris and pupils black ( Tables 4–6 ; Fig. 4 & 5 ).

Description of holotype. Adult male SVL 378 mm and Tal 78 mm; rostral wider than tall; head narrow, elongate, somewhat bulbous, longer than wide; nasals undivided; internasals shorter than prefrontals; posterior margin of prefrontals contact eye; frontal hexagonal, slightly wider than long; loreals present, longer than tall; supraoculars subpentagonal, approximately half the length and a third the width of frontal; preoculars absent; two postoculars present on both left and right side of head, lower postocular extending to below orbit; suboculars absent; supralabials 6/6 with 3rd and 4th contacting orbit and 6th elongate; temporals 1+2/2(+1)+2, i.e. on left side of head, upper anterior temporal is fused with parietal resulting in a single lower anterior temporal and two posterior temporals, while on right side of head there are two anterior temporals and two posterior temporals but between lower anterior and lower posterior termporal is an additional scale resulting in two upper temporals and three lower temporals; mental triangular wider than long; anterior inframaxillary hexagonal, in contact with infralabials 1–3; two pairs of posterior inframaxillaries following anterior inframaxillary, first pair of posterior inframaxillaries slightly squarish, rhomboid-shaped, second pair more heaxagonal, elongated; infralabials 6/6 with 3 rd pair in medial contact. Body long, slender, laterally compressed, bearing a prominent keel-shaped vertebral region; dorsal scales smooth, in 15/15/15 rows, vertebrals greatly enlarged; 173 ventrals; 53 divided subcaudals; cloacal scute entire; tail tapering to a point.

Colouration in preservation ( Figs. 4A & B ). The ground colour of the head, body and tail is dark-brown. The colour is darker on the back along the vertebral scale rows and lightens up to light-brown on the lower flanks. Along the body and tail are 44 dark, rhomboidal bands ranging from 1–3 dorsal scales in length starting from neck. These bands are indistinct on the dorsum and are only clearly visible along the lower flanks and extend onto the corners of the ventral scales. The chin and throat are dark-brown while the iris and pupils are black. The venter is cream to light-yellow and bears dark, lateral blotches from the extensions of the dorsal bands that meet corners of the ventral scales.

Variation ( Figs. 4 & 5 ). The juvenile paratype ZRC 2.2742 approaches the holotype in pholidosis but has seven supralabials on the right side of the head, five pairs of infralabials, 48 body bands that are more prominent than those on the adult holotype and a lighter vertebral region ( Table 4 ; Fig. 4C & D ). Based on photographs of other specimens from Mount Kinabalu, Sabah that have been tentatively identified as this species, the ground colour of some are dark-grey with nearly obscure banding ( Fig. 5A ), while in others there is a poorly defined, broken, whitish, vertebral stripe ( Fig. 5D ) and the ventral colouration is white ( Fig. 5B ). The juveniles are more contrastingly patterned than the adults with the lower dorsal scale rows white, forming a poorly-defined white stripe along the lower flanks; more prominent banding on the body and tail; and a very prominent, broken, white, vertebral stripe that appear as a series of white spots along the back ( Fig. 5C ).

A. jamilinaisi sp. nov. A. jamilinaisi A. stuebingi sp. nov.

sp. nov.

SP 04076 ZRC 2.2742 SP 04679 SP 04806 ZMB 65429 MCZ R43591

(holotype) (paratype) (holotype) (paratype) (paratype) (paratype)

Mount Trusmadi, Tam- Marei Parei, Mt. Minduk Sirung, Crocker Kg. Desa, Kundasang, Mount Kinabalu, Kadmayan Rd., Kiau,

bunan, Sabah Kinabalu, Sabah Range Park, Sabah Sabah Sabah Mount Kinabalu , Sabah

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A. jamilinaisi sp. nov. A. jamilinaisi A. stuebingi sp. nov.

sp. nov.

SP 04076 ZRC 2.2742 SP 04679 SP 04806 ZMB 65429 MCZ R43591

(holotype) (paratype) (holotype) (paratype) (paratype) (paratype)

Mount Trusmadi, Tam- Marei Parei, Mt. Minduk Sirung, Crocker Kg. Desa, Kundasang, Mount Kinabalu, Kadmayan Rd., Kiau,

bunan, Sabah Kinabalu, Sabah Range Park, Sabah Sabah Sabah Mount Kinabalu , Sabah

Comparison. Asthenodipsas jamilinaisi sp. nov. can be differentiated from Aplopeltura boa by its higher number of mid-dorsal scale rows (15 vs. 13) and divided subcaudals ( de Rooij 1917; Grossmann & Tillack 2003; Stuebing et al. 2014). Asthenodipsas jamilinaisi sp. nov. can be differentiated from members of the genus Pareas by its possession of preocular and subocular scales (absent vs. present), supralabials in contact with orbit (3 rd & 4 th contact orbit vs. no supralabials in contact with orbit) and anterior single inframaxillary (present vs. absent) ( Grossmann & Tillack 2003). Asthenodipsas lasgalenensis , A. tropidonotus and A. vertebralis can be differentiated from A. jamilinaisi sp. nov. by their possession of more pairs of posterior inframaxillaries (three vs. two) and pairs of infralabials in contact (1 st vs. 3 rd). In addition, A. vertebralis and A. tropidonotus can be differentiated A. jamilinaisi sp. nov. by their higher number of ventrals (195–215 vs. 173–175) ( Loredo et al. 2013). A. jamilinaisi sp. nov. can be differentiated from A. malaccana by its lower number of supralabials (6 vs. 7–8) and colour pattern (dark dorsum with indistinct banding vs. light-grey to brown body with distinct banding or blotches and a prominent dark patch on the neck) (Chan-ard et al. 2015; Das 2010; de Rooij 1917; Stuebing et al. 2014). Asthenodipsas jamilinaisi sp. nov. can be distinguished from A. laevis by its larger adult length, (max SVL 378 mm vs. 373 mm), higher number of ventral scales (173–175 vs. 148–173), dorsal scales rows (15/15/15 vs. 15/15/13) and sharp vertebral keel (present vs. absent) ( Figs. 4E & 4F ) ( Tables 3–6 ). A. jamilinaisi sp. nov. can be differentiated from A. stuebingi sp. nov. by its higher number of subcaudals (52–53 vs. 35–47), higher number of ventrals in males (173–175 vs. 165), size of vertebral scales (greatly enlarged vs. slightly enlarged), colour pattern (dark overall colouration of dorsum with indistinct banding vs. light-coloured head and dorsum with a dark neck patch and distinct bands) and body form (gracile and laterally compressed vs. robust and stout) ( Tables 3–6 ). A key to the family Pareidae of Borneo is presented below.

Distribution ( Fig. 8 ). Asthenodipsas jamilinaisi sp. nov. is only known from the highlands of Sabah, East Malaysia at Mount Trusmadi and Mount Kinabalu. It may possibly be found at other montane areas in Borneo.

Etymology. The specific epithet jamilinaisi is a patronym in honour of Dr. Jamili Nais, the Director of Sabah Parks for his contributions to the research and conservation of biodiversity in the state and the first Malaysian to be appointed as a member of the World Heritage panel of the International Union for Conservation of Nature ( IUCN).

Natural History. Little is known about the natural history of A. jamilinaisi sp. nov. except that it is a montane species that has only been found from 1500 to 2500 m a.s.l. in Sabah. Similar to other slug snakes it is nocturnal and has been found crawling in the vegetation. The paratype and another juvenile ( Fig. 5C ) were found during May which indicates that breeding takes place in the earlier half of the year. Presumably it also feeds on snails and slugs like other members of the family.

Figures

FIGURE 4. A & B. Dorsum and venter of holotype of Asthenodipsas jamilinaisi sp. nov. (SP 04076). C & D. Dorsum and venter of paratype of A. jamilinaisi sp. nov. (ZRC 2.2742). Photographs by Kelvin Lim. E. Sharp vertebral keel of the holotype of A. jamilinaisi sp. nov. (SP 04679) as indicated by arrow. F. Absence of sharp vertebral keel on A. laevis (SP 04138) from Borneo as indicated by arrow.

FIGURE 5. Variation in Asthenodipsas jamilinaisi sp. nov. from Mount Kinabalu, Sabah. A & B. Dorsum and venter of same adult individual. C. Juvenile. D & E. Adults. (Photographs by Björn Lardner [A–B], Kurt H.P. Guek [C & E] & Steven Wong [D]).

FIGURE 8. Distribution of Asthenodipsas jamilinaisi sp. nov. (yellow), A. stuebingi sp. nov. (red) and reported localities of A. laevis (blue) in Borneo. Star = type locality.