Tytthoscincus keciktuek, Grismer & Wood Jr & Ahmad & Baizul-Hafsyam & Afiq-Shuhaimi & Rizal & Quah, 2018

Grismer, L. Lee, Wood Jr, Perry L., Ahmad, Amirrudin B., Baizul-Hafsyam, B. S., Afiq-Shuhaimi, M., Rizal, Syed A. & Quah, Evan S. H., 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 : 100-102

Tytthoscincus keciktuek sp. nov.

Suggested common names: Sungai Peres Forest Skink and Mengkarung Hutan Sungai Peres

( Fig. 6 )

Holotype. Adult female ( LSUHC 13859 ) collected along a small tributary of the Sungai Peres, Sekayu, Hulu Terengganu, Terengganu State, Peninsular Malaysia (4.9596° N, 102.9596° E; 74 m in elevation) by Murni- Azima, Amirrudin B. Ahmad, and M. Afiq-Shuhaimi. on 17 September 2017.

Diagnosis. Tytthoscincus keciktuek sp. nov. can be differentiated from all other species of Tytthoscincus in the upland clade by having the combination of 7`1, superciliaries; a deeply set, unpigmented tympanum; enlarged pectoral scales; 30 midbody scale rows; 66 paravertebral scales; 60 ventral scales; keeled, subdigital lamellae; seven subdigital lamellae on the third finger; 11 subdigital lamellae on the fourth toe; EO/HL = 0.12; HL/SVL = 0.21; AXG/SVL = 0.54; FL/SVL = 0.25; HDL/SVL = 0.37; and a maximum SVL of 36.2 mm (Tables 5,6). All non-ratiometric 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 female, SVL 36.2 mm; broken tail length 31.1 mm; axilla-groin length 19.7 mm; head length 7.5 mm; head width 4.4 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, first loreal posteriorly, first supralabial ventrally; nostril in center of nasal; supranasals absent; two loreals; upper and lower preocular present; lower preocular followed by a series of six suboculars; seven superciliaries, posterior superciliary elongate and projecting dorsomedially; one postsuperciliary; two postoculars; 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 0.9 mm, circular, lacking anterior lobules; and tympanum deeply set, non-pigmented.

Body scales smooth, cycloid, imbricate; ventral scales slightly larger than dorsal scales; 30 longitudinal scale rows around midbody; 66 paravertebral scale rows; 60 ventral scale rows; slightly enlarged median precloacal scales overlapping outer precloacal scales; tail round in cross-section; subcaudals slightly larger than dorsal caudals anteriorly; limbs relatively robust, short (FL/SVL = 0.25; HDL/SVL = 0.37), 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, 11 on fourth toe.

Coloration in life ( Fig. 6 ). Overall dorsal ground color of head, body, limbs, and tail brown, generally patternless and lacking light-colored speckles; top of head weakly speckled with dark-colored markings; rostrum light-colored; diffuse, immaculate, dull-orange, dorsolateral stripe extends from parietal region to anterior margin of flank before fading; supralabials and infralabials alternately banded with light and dark bars; dorsal portion of flanks slightly lighter than dorsum; all ventral surfaces dull-yellow to beige, generally immaculate; distal portions of forelimbs and palmer surfaces dark; planter surface dark; and wide, dark, diffuse lateral strip on tail.

Distribution. Tytthoscincus keciktuek sp. nov. is known only from the type locality along the Sungai Peres, Terengganu, Peninsular Malaysia ( Fig. 2 ), however, it is likely to range throughout the entire riparian system of the Sekayu region.

Natural history. Tytthoscincus keciktuek sp. nov. (LSUHC 13859) is a leaf-litter species inhabiting riparian systems in lowland dipterocarp forest ( Fig. 7 ). The holotype (captured in a pitfall trap) is a gravid female indicating that September falls within the reproductive season of this species.

Etymology. The name " keciktuek ", is a colloquial word in the local dialect of rural Terengganu that means “small, small things” and refers to all small animmals. It is used here in reference to the small size of all the species of the upland clade of Tytthoscincus .

Comparisons. Tytthoscincus keciktuek sp. nov. is most closely related to the undescribed species from the Tembak Reservoir area from which it differs by an uncorrected pairwise sequence divergence of 5.3%. Unfortunately, the Tembat specimen was so badly damaged by insects in a pitfall trap that no morphological data were unobtainable. Differences between T. keciktuek sp. nov. and T. monticolus sp. nov. are presented above. Differences between T. keciktuek sp. nov. and all other species of the upland clade are presented in Table 6.

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Figures

FIGURE 2. Type localities for Tytthoscincus keciktuek sp. nov. and T. monticolus sp. nov. and their closest relatives T. perhentianensis and Tytthoscincus sp. nov., respectively, in Peninsular Malaysia.

FIGURE 6. Upper: type specimen (LSUHC 13858) of Tytthoscincus monticolus sp. nov. collected from a hilly area near Sungai Bubu, Sekayu, Hulu Terengganu, Terengganu State, Peninsular Malaysia. Photograph by A. B. Ahmad. Middle: type specimen (LSUHC 13859) of Tytthoscincus keciktuek sp. nov. collected along a small tributary of the Sungai Peres, Sekayu, Hulu Terengganu, Terengganu State, Peninsular Malaysia. Photograph by A. B. Ahmad. Lower: Tytthoscincus butleri (LUSHC 13860) from a new lowland locality at Bukit Mertajam, Penang, Peninsular Malaysia. Photograph by E.S.H. Quah.

FIGURE 7. Left: General habitat of Tytthoscincus monticolus sp. nov. and T. keciktuek sp. nov. from the Sekayu region of Hulu Terengganu. Photograph by L. L. Grismer. Upper right: microhabitat at the type locality of T. monticolus sp. nov. near Sungai Bubu, Sekayu, Hulu Terengganu, Terengganu State, Peninsular Malaysia. Photograph by M. Afiq-Shuhaimi. Lower right: microhabitat at the type locality of T. keciktuek sp. nov. from Sungai Peres, Sekayu, Hulu Terengganu, Terengganu State, Peninsular Malaysia. Photograph by M. Aqmal-Naser.