Tytthoscincus monticolus

Grismer, L. Lee, Wood Jr, Perry L., Ahmad, Amirrudin B., Baizul-Hafsyam, B. S., Afiq-Shuhaimi, M., Rizal, Syed A. & Quah, Evan S, 2018, Two new Tytthoscincus Linkem, Diesmos, & Brown (Squamata; Scincidae) from Peninsular Malaysia and another case of microsyntopy between ecologically specialized, unrelated, leaf-litter species, Zootaxa 4425 (1), pp. 87-107: 98-100

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Tytthoscincus monticolus

sp. nov.

Tytthoscincus monticolus  sp. nov.

Suggetsed common names: Sungai Bubu Forest Skink and Mengkarung Hutan Sungai Bubu

( Fig. 6 View Figure )

Holotype. Adult male ( LSUHC 13858View Materials) collected from a hilly area near Sungai Bubu, Sekayu, Hulu Terengganu, Terengganu State, Peninsular Malaysia (4.9710° N, 102.9531° E; 174 m in elevation) by M. Afiq-Shuhaimi and Baizul-Hafsyam B. S. on 5 August 2017.GoogleMaps 

Diagnosis Tytthoscincus monticolus  sp. nov. can be differentiated from all other species of Tytthoscincus  in the upland clade by having the combination of 8`1, superciliaries; a deeply set, unpigmented tympanum; enlarged pectoral scales; 31 midbody scale rows; 69 paravertebral scales; 68 ventral scales; keeled, subdigital lamellae; seven subdigital lamellae on the third finger; 12 subdigital lamellae on the fourth toe; EO/HL = 0.16; HL/SVL = 0.17; AXG/SVL = 0.55; FL/SVL = 0.22; HDL/SVL = 0.33; and a maximum SVL of 36.6 mm (Tables 5,6). All characters are scored across all other Tytthoscincus  and species of Sphenomorphus  suspected of being Tytthoscincus in Grismer et al. (2016a:237)  and Karin et al. (2016:416).

Description of holotype. Adult male, SVL 36.6 mm; regenerated tail length 29.4 mm; axilla-groin length 20.0 mm; head length 6.4 mm; head width 3.8 mm; rostral wider than long, in broad contact with frontonasal; frontonasal wider than long; prefrontals large, in broad contact on midline; frontal elongate, triangular, in contact with first two supraoculars; four supraoculars; frontoparietals in contact posterior to frontal, contacting second, third, and fourth supraoculars anterolaterally and parietals and interparietal posteriorly; interparietal diamondshaped, large, slightly projecting posteriorly, eyespot in posterior projection; parietals large, in medial contact posterior to interparietal, contacting fourth supraocular anteriorly; six nuchal scales; nasals small, widely separated, trapezoidal, contacting rostral anteriorly, frontonasal dorsally, loreal posteriorly, first supralabial ventrally; nostril in center of nasal; supranasals absent; loreal single; upper and lower preocular present; lower preocular followed by a series of seven suboculars; eight superciliaries, posterior superciliary elongate and projecting dorsomedially; two postoculars; one postsuperciliary; six supralabials, third, fourth, and fifth below eye; two postsupralabials; two primary temporals; four secondary temporals, uppermost contacting parietal; lower eyelid transparent, scaly, no enlarged central window; mental twice as wide as long; single, large postmental, contacting first infralabial on each side; two enlarged pairs of chin shields posterior to postmental, anterior pair contacting medially, posterior pair widely separated posteriorly by a single scale; anterior and posterior chinshield pairs contacting first, second, and third infralabials; five infralabials; external ear opening 1.0 mm, circular, lacking anterior lobules; and tympanum deeply set, non-pigmented.

Body scales smooth, cycloid, imbricate; ventral scales slightly larger than dorsal scales; 31 longitudinal scale rows around midbody; 69 paravertebral scale rows; 68 ventral scale rows; slightly enlarged median precloacal scales overlapping outer precloacal scales; tail slightly compressed laterally; subcaudals slightly larger than dorsal caudals; limbs relatively robust, short (FL/SVL = 0.22; HDL/SVL = 0.33), widely separated when adpressed; scales of dorsal surfaces slightly larger than those of ventral and posterior surfaces; palmar and plantar scales raised; and digits moderate in length, scales on dorsal surfaces in single row, subdigital lamellae keeled, seven on third finger, 12 on fourth toe.

Coloration in life ( Fig. 6 View Figure ). Overall dorsal ground color of head, body, limbs, and tail dark-brown; hind limbs darker than forelimbs, both limbs mottled; top of head and body speckled with light-colored markings, those above the shoulder tending to coalesce to form a diffuse dull-orange stripe; supralabials and infralabials alternately banded with light and dark bars; dorsal portion of flanks dark, highlighting the light-colored dorsal spots; all ventral surfaces dull-yellow to beige, generally immaculate; distal portions of forelimbs and palmer surfaces dark; planter surface dark; and subcaudal region stippled with dark-brown.

Distribution. Tytthoscincus monticolus  sp. nov. is known only from the type locality near the Sungai Bubu, Terengganu, Peninsular Malaysia ( Fig. 2 View Figure ), however, it is likely to range throughout the entire lowland system of the Sekayu region.

Natural history. The holotype of Tytthoscincus monticolus  sp. nov. (LSUHC 13858) is a leaf-litter species inhabiting hilly areas along riparian systems in lowland dipterocarp forest ( Fig. 7 View Figure ) and was captured in a pitfall trap.

Etymology. The specific epithet monticolus  , comes from the Latin monti meaning mountain and colus meaning dweller of or within and refers to this species inhabiting hilly areas.

Comparisons. Tytthoscincus monticolus  sp. nov. is most closely related to T. perhentianensis  ( Fig. 4 View Figure ) and differs from it by an uncorrected pairwise sequence divergence of 3.5%. It is differentiated from T. perhentianensis  morphologically by having one vs. two loreal scales; 69 vs. 65 or 66 paravertebral scales; 68 vs. 61 or 62 ventral scales; seven vs. six subdigital lamellae on the third finger; and 12 vs. 10 subdigital lamellae on the fourth toe. It differs further by having a larger ear opening (0.16 vs 0.13–0.14 EO/HL); a shorter head (0.17 vs. 0.22–0.23 HL/ SVL); longer hind limbs (0.33 vs. 0.29–0.30 HDL/SVL); and a larger maximum SVL (36.2 mm vs. 30.0 mm: Table 6). It differs from T. keciktuek  (see description below) with which it is likely syntopic by an uncorrected pairwise sequence divergence of 9.8% and having one vs. two loreals; 68 vs 60 ventral scale rows; a larger ear opening (0.16 vs 0.12 EO/HL); a shorter head (0.17 vs. 0.21 HL/SVL); shorter forelimbs (0.22 vs. 0.25 FL/SVL); shorter hind limbs (0.33 vs. 0.37 HDL/SVL); and a dorsal pattern bearing white speckling vs. being nearly unicolor ( Table 5; Fig. 6 View Figure ). Differences between T. monticolus  sp. nov. and all other species of the upland clade are presented in Table 6.