Trachylepis principensis Ceríaco, Marques & Bauer, 2016, sp. nov.

Trachylepis principensis sp. nov. (Figs 5–7) Lygodactylus [sic!] maculilabris (Henriques 1917: 81) Mabuia maculilabris (Gray) (Bocage 1903: 53; Boulenger 1906: 205) Mabuya maculilabris, Gray (Manaças 1958: 184; 1973: 223; Schätti & Loumont 1992: 29; Hofer 2002: 82) Trachylepis cf. maculilabris – Príncipe (Ceríaco 2015: 512) Holotype. MB03-000957, adult male collected on a tree near Santo Cristo (N: 1.63822, E: 7.43317; WGS-84), Príncipe Island, Republic of São Tomé and Príncipe by Luis M.P. Ceríaco, Mariana Marques and Pedro Ceríaco on 11 February 2015 (Figs 6). Paratypes. All specimens from the Island of Príncipe, Republic of São Tomé and Príncipe. Twelve specimens: MB03-000909, adult male collected in Roça Pincaté (N: 1.63205, E: 7.39869; WGS-84) by Luis Ceríaco and Mariana Marques on 20 March 2013; MB03-000951 adult female collected in Roça Porto Real (N: 1.624324, E: 7.405327; WGS-84), by Ostelino da Silva on 1 March 2014; MB03-000955, adult female, MB03-000956, collected in the same locality, same date and by the same collectors as the holotype; MB03-000979, adult female collected in Torre de Comunicação Sundy (N: 1.00000, E: 7.37924; WGS-84), by Hélio Vicente on 12 February 2015; CAS 219172, adult female collected south of Roça Sundy (N: 1.66239, E: 7.38550; WGS-84) by R.C. Drewes and R.E. Stoelting on 21 April 2001; CAS 219188, adult male, CAS 219189, adult female, CAS 219190, adult female, all collected in Nova Estrela (N: 1.62050, E: 7.43036; WGS-84) by R.C. Drewes and R.E. Stoelting on 21 April 2001; CAS 219358, adult male, CAS 219361, adult female, both collected in Praia Abade (N: 1.63075, E: 7.45600; WGS-84) by R. E. Stoelting on 16 May 2001; CAS 238898, adult female collected at Bom Bom resort (N: 1.69817, E: 7.40267; WGS-84) by K. Monson on 3 May 2008. Diagnosis. An elegant medium-sized skink (SVL 58.5–88.3 mm), tail length usually twice SVL (TL/ SVL169.3–230.9%, mean 202.2%). Moveable eyelids with a yellow border clearly contrasting with the brown facial colouration, the lower eyelid with a translucent palpebral disk. Supraciliaries usually 5, sometimes 6; four labials anterior to subocular; rectangularly-enlarged subocular, in contact with the lip and not reduced basally by the intrusion of adjacent supralabials; snout slender and acuminate; infralabials bluish and supralabials bluish at the base but brown at the top; mental pale blue. Supranasals usually in broad contact, or in contact at a point. Parietals always in contact. No distinct longitudinal or transverse dorsal bands. Back uniformly brownish, sometimes with a few scattered dark speckles and a dorsolateral line composed of white spots starting in the temporal area and extending to mid-body, and belly light blue in alcohol, and bluish to green in live specimens. Midbody scale rows 31–33, paravertebral scales 47–51, with 5–6 keels on vertebral and dorsal scales, paraventral scales 57–63. Lamellae beneath fourth finger 16–18, beneath fourth toe 21–22. Description of holotype. Adult male in perfect condition. Arrangement and relative size of head, body, and tail scales typical for Trachylepis. Delicate and cylindrical body with robust legs. Fore- and hind-limbs overlap when pressed against the body. SVL 83.4 mm, TL 156.1 mm, HL 16.5 mm, with relatively acuminate snout (HL/ HW 163.3%). Other relevant measurements are presented in Table 5. Rostral visible from above, large nostrils set posteriorly so that postnasal effectively borders nostril. Supranasals separated, frontonasal wider than long, laterally in contact with loreal scale. Prefrontals hexagonal, separated, in medium contact with the following head shields: frontonasal, loreal, first supraocular, first supraciliary and frontal. Two loreals, the posterior and dorsal areas of the largest loreal borders an enlarged pre-ocular. Frontal length the same as distance between anterior tip of frontal and tip of snout, frontal in contact with three supraoculars on either side. Frontoparietals two, in contact with each other and the frontal, third and fourth supraoculars, parietal and interparietal. Frontoparietal plus interparietal length equal to frontal length. Interparietal three times longer than wide, with visible parietal foramen, parietals about five times larger than frontoparietals and in contact at the anterior point of the interparietal. Parietals in contact. A pair of large, broad nuchals collectively bordered by a total of six dorsals. Supraciliaries five, second largest. Supralabials seven, the fifth being the subocular. Infralabials six. Postmental borders seven scales. Transparent scale present in lower eyelid, as is usual for Trachylepis. Pre-temporals two. Tympanum visible, approximately as high as the mouth is long. Rostral wider than deep. Dorsal scales have 5–7 keels. Ventral scales smooth. MSR 33, SAD 48, SAV 58. Limbs with five digits; scales on soles of hands and feet smooth. Relative length of fingers IV>III>II>V>I, relative length of toes IV>III>V>II>I. Finger-IV lamellae 16, Toe-IV lamellae 20. Tail long, thin and smoothly tapering. In preservative, background color of flanks and upper side of head, neck, dorsum, legs and tail homogenous dark-brown. Venter uniformly bluish, palmar regions of hands and feet whitish. The alcohol-preserved holotype has a uniformly dark brown dorsal colouration, without speckles. Venter uniform light-blue. The palmar region of the hands and feet are whitish. Infra- and supralabials light blue. Above the labials the head is uniformly dark brown as is the dorsum. Eyelids yellowish-white. Variation. Variation in measurements and principal scale counts is shown in Table 5. Parietals always in contact. The frontoparietals are in contact with each other in all paratypes, whereas the supranasals are in broad contact in most paratypes except CAS 219361 and 219372 where they are in very narrow contact. Contact between prefrontals varies considerably: CAS 238898, prefrontals in narrow contact; CAS 219172, 219188 and 219189, broad contact; CAS 219190, 219358 and 219361, separated. Colouration of paratypes is uniform and agrees with the holotype, with the exception of a faint lighter dorsolateral stripe comprising small white spots starting at the temporals and reaching the middle of the body in CAS 219188, 219189, 219190, 219358 and 219172. Paratypes CAS 238898 and 219361 have only a few scattered small black dots on the dorsum. Colouration. Color in life is uniform greenish-brown on the entire dorsum, with no visible spots, markings or dorsolateral stripes; scales of the venter greenish-yellow, also without any other markings. The eyelids are distinctly yellow, strongly contrasting with the darker head colouration. Comparison with other Gulf of Guinea oceanic island species. Table 2 summarises the most important distinguishing characteristics between T. principensis and all other Gulf of Guinea oceanic island Trachylepis. Comparing T. principensis with T. maculilabris from West Africa, the new species has a larger SVL, lower number of scales from the nuchals to the base of the tail, a greater distance from front of the eye to tip of snout, larger relative tail length, higher numbers of lamellae under the fourth toe and fourth finger (Table 2), and absence of lateral stripes, lightly colored lines starting at the eye and reaching the forelimbs and of dorsal speckles as is usual in T. maculilabris. In terms of colouration, T. principensis lacks a yellow or white ear (usual in T. maculilabris), has greenish-yellow venter (pale yellow in T. maculilabris), and highly contrasting, vivid yellow eyelids. Comparing T. principensis with T. thomensis, the Príncipe species has a smaller SVL, greater tail length, slender and more acute tail, with a slender and shorter head, a smaller interparietal, a smaller internarial distance, a smaller distance from the front of the eye to the parietals, a smaller distance from the front of the eye to the tip of the snout, and a more acuminate head, and lower numbers of dorsal scales between the nuchals and the base of the tail (Table 2). In terms of colouration, T. principensis has a uniformly dark brown dorsum with contrasting yellow eyelids and bluishgreen venter, whereas T. thomensis typically has a brown dorsum with black and white speckles and a yellow venter, orange-brown colouration speckled with white and black dots on the back, and black and white blotches under the eye and on supralabials. Comparing T. principensis with T. adamastor, the new species has a considerably smaller SVL, higher TL/SVL ratio, lower numbers of SAV, and higher number of LUFT (Table 2), two pre-temporals (one in T. adamastor), prefrontal scales separated or in narrow contact (in contact forming a suture in T. adamastor), and the very darkbrown and white-speckled dorsum and greyish ventrum of T. adamastor contrasts with the uniformly brown dorsum and greenish ventrum of T. principensis. Trachylepis principensis is easily distinguished from the sympatric T. affinis by several morphological characters, but primarily by the absence of any dorsolateral stripes, larger size, very acuminate snout, and distinctive yellow eyelid. Trachylepis principensis has greater SVL, less bulky head, higher numbers of scales around the midbody, and greater numbers of keels on the dorsal scales (Table 2). Colouration is strikingly contrasting, whereas T. principensis has homogenous colouration (dark brown above, greenish-yellow below, no pattern) and T. affinis has a distinctive longitudinal band on the lateral sides of the body. Comparing T. principensis with T. ozorii, the newly described species has lower numbers of supraciliaries, higher numbers of keels on dorsal scales, lower numbers of scales around the midbody, and lower numbers of paravertebral scales (Table 2). The dorsal colouration is also different, with T. principensis having a uniformly dark brown dorsum, while T. ozorii has a dark brownish dorsum covered with black speckles. Distribution. Tra

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