Sphenomorphus senja Grismer & Quah, 2015, sp. nov.
Creators: name: Grismer, L. Lee
name: Quah, Evan S. H.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Scincidae
Sphenomorphus
Sphenomorphus senja

description: Sphenomorphus senja sp. nov.
Titiwangsa Forest Skink Figure 2
Holotype. Adult male (LSUHC 11688) collected from Gunung Brinchang, Cameron Highlands, Pahang, West Malaysia (04° 31.105 N 101° 22.571 E; at 1811m) on 26 April 2014 by Evan S. H. Quah.
Paratype. BM 1911.12.5.10. As noted by Boulenger (1912) the specimen was collected by Mr. J. N. Sheffield at 6,900 feet on Gunong Grah [=Gunung Gerah] in the Titiwangsa Mountain Range, Perak during August 1905.
Diagnosis. Adults reaching 65.0 mm SVL; body slender, elongate; limbs separated when adpressed; 32 smooth, midbody scale rows; 72 or 73 paravertebral scales; 68 ventral scale rows; four supraoculars; prefrontals in narrow contact or slightly separated; two loreal scales; 13–17 smooth, lamellae beneath Toe IV; enlarged, preanal scales; dorsal body bands absent; numerous dark markings on back and flanks.
Description of holotype. Adult male, SVL 60.0 mm; head moderate, snout rounded in dorsal and lateral profile, indistinct from neck; rostral wider than long, in broad contact with frontonasal; frontonasal wider than long, not divided anteriorly; prefrontals large, separate or in narrow contact; frontal elongate, diamond-shaped, in contact with first two supraoculars; four supraoculars; frontoparietals in contact posterior to frontal, contacting posterior portion of second, all of third, anterior one-half of fourth supraocular, parietals, and interparietal posteriorly; interparietal diamond-shaped, large, slightly projecting posteriorly; parietal eyespot absent; parietals large, in contact posterior to interparietal, contact posterior corner of fourth supraocular anteriorly; nuchal scales not enlarged; nasals large, widely separated, trapezoidal, contacting rostral anteriorly, frontonasal dorsally, first loreal posteriorly, first supralabial ventrally; nostril in center of nasal; supranasals absent; two loreals, posterior broader than anterior, anterior tallest; two preoculars in contact with posterior margin of second loreal, ventral preocular largest; eight supraciliaries, posteriormost elongate, projecting dorsomedially; two pretemporals; discontinuous row of five suboculars contacting supralabials; seven supralabials, fifth below center of eye and interrupting subocular row; two postsupralabials; one primary temporals; two secondary temporals, uppermost contacting parietals; small, granular scales at posterior corner of eye; lower eyelid transparent, scaly, lacking an enlarged central disc; mental twice as wide as long, rectangular; postmental large, single, contacting first and second infralabials; two pairs of enlarged sublabials following postmental, anterior pair contacting medially, posterior pair separated by a single scale, both pairs contacting infralabials; six infralabials, first smallest; external ear opening large, lacking anterior lobules; tympanum deeply recessed.
Body scales smooth, cycloid, imbricate; ventral scales slightly larger than dorsal scales; 32 longitudinal, scale rows around midbody; 72 paravertebral scale rows; 68 ventral scale rows; two enlarged, medial, preanal scales; limbs small, separated when adpressed; scales of dorsal surface slightly larger than those of ventral surface; palmar and plantar scales rounded; supradigital scales on hand in multiple rows proximally, in a single, enlarged, row distally; supradigital scales on foot in multiple rows throughout digit; 17 smooth, subdigital lamellae on fourth toe; first digit of hand not vestigial; tail robust, not constricted at base, approximately 1.3 (not original) SVL, cylindrical; subcaudal scales slightly larger than dorsal caudal scales.
Coloration in life (Fig. 2). Ground color of dorsal surfaces of head, body, limbs, and tail brown, overlain with numerous darker flecks giving it a speckled appearance; a wide, diffuse, black, lateral stripe extends from posterior margin of eye to where it is most prominent on flanks thence becoming more diffuse and terminating on anterior portion of tail; lateral stripe bordered dorsally by a faint, lighter colored stripe extending from eye to axilla after which it transforms into a series of whitish flecks on trunk; lateral stripe is bordered ventrally by numerous, irregularly shaped, brown and white spots on neck; small whitish spots occur within the stripe; the lower portion of flanks below lateral stripe vermillion orange; gular region, throat and neck beige; pectoral region, abdomen, and undersides of limbs yellow; anterior two-thirds of subcaudal region orange, posterior one-third mottled in orange and black.
Variation. The paratype BM 1911.12.5.10 closely approaches the holotype in coloration except that the lateral stripe is bordered ventrally by numerous, irregularly shaped, white spots just within the lower region of the stripe, giving it a poorly defined and broken ventral margin and the lower flanks are yellow instead of vermillion (Lim 1998). This may be because the holotype was a reproductively active male (enlarged testes examined) bearing the breeding coloration. The frontonasal scale of the holotype is not divided whereas it is in the paratype; the prefrontals are separate in the holotype as opposed to being in narrow contact in the paratype; the holotype has eight as opposed to nine superciliaries; one as opposed to two primary temporals; and 17 as opposed to 13 subdigital lamellae. A discrepancy of four subdigital scales could be considered significant, however, neither Boulenger (1912) or Lim (1998) explained the method by which this count was taken. We can adjust our method of counting to bring our count down to 15 but elect not to so as to remain consistent with those counts of other Malaysian skinks (Grismer 2011). Other meristic differences are presented in Table 1.
malayanus senja Distribution. Sphenomorphus senja sp. nov. is known only from Gunung Gerah, Perak and Gunung Brinchang, Pahang in the Titiwangsa Mountain Range (Fig. 1), however, it is likely to range further to the north and south along this upland corridor.
Natural history. Sphenomorphus senja sp. nov is a upland mossy, cloud forest species (Fig. 3) ranging from at least 1811 m in elevation at Gunung Brinchang to 2200 m in elevation at Gunung Gerah (Boulenger 1912). The holotype was collected at night beneath leaf-litter along an earthen bank following several days of heavy rain.
Etymology. The specific epithet senja is the Malay word for “twilight” or “dusk” at which time the sky above Gunung Brinchang turns vermillion orange, matching the color on the flanks of Sphenomoprhus senja sp. nov.
Comparisons. Sphenomorphus senja sp. nov. is most similar to Sphenomorphus malayanus of Gunung Singgalang in West Sumatra but can be separated from it by having a larger SVL (60.0– 65 mm versus 53 mm, assuming the S. malayanus specimen is an adult); a deep, as opposed to a shallow tympanum; 72 or 73 versus 76 paravertebral scales; eight or nine superciliary scales as opposed to 10; and the posteriromost superciliary scale being large as opposed to small. The anterior subcaudal region is orange in S. senja sp. nov. and in S. malayanus is reported to be yellowish gray (“giallo suducio”, Doria [1888]) or “whitish” (de Rooij, 1915). Unfortunately the holotype of S. malayanus could not be located for direct examination (David Gower in litt. 2014). The only other species in Peninsular Malaysia with which S. senja sp. nov. might be confused with is S. cameronicus (Smith) which occurs at lower elevations (1500 m) in Cameron Highlands (Grismer 2011). We examined three specimens of S. cameronicus (LSUHC 9738, 9819–20) from its type locality at Tanah Rata, Cameron Highlands and find that S. senja sp. nov. differs from it in that the adpressed limbs do not overlap as opposed to overlapping slightly; having 32 midbody scale rows as opposed to 34–38; having 13–17 as opposed to 20 or 21 subdigital lamellae on the fourth toe; having vermillion colored flanks in breeding males as opposed to beige flanks in breeding males (Grismer 2011); having yellow as opposed to beige pectoral and abdomen regions; and that the anterior two-thirds of the subcaudal region is orange as opposed to beige.
description: Published as part of Grismer, L. Lee & Quah, Evan S. H., 2015, The Rediscovery of Sphenomorphus malayanus Doria, 1888 (Squamata: Scincidae) from the Titiwangsa Mountain Range of Peninsular Malaysia and its re-description as S. senja sp. nov., pp. 63-70 in Zootaxa 3931 (1) on pages 65-67, DOI: 10.11646/zootaxa.3931.1.4, http://zenodo.org/record/288140