Spondylurus turksae, Hedges & Conn, 2012

Hedges, S. Blair & Conn, Caitlin E., 2012, A new skink fauna from Caribbean islands (Squamata, Mabuyidae, Mabuyinae) 3288, Zootaxa 3288 (1), pp. 1-244 : 211-214

Spondylurus turksae sp. nov.

Turks Islands Skink

( Figs. 73G , 83 , 84 )

Mabuya sloanii — Barbour, 1916:219 (part).

Mabuya mabouya sloanii — Dunn, 1936:544 (part).

Mabuya mabouya — Barbour, 1937:147 (part).

Mabuya mabouya sloanei — Schwartz & Thomas, 1975:141 (part).

Mabuya mabouya sloanei — MacLean et al., 1977:21 (part).

Mabuya mabouya sloanei — Schwartz & Henderson, 1988:151 (part).

Mabuya mabouya sloanei — Schwartz & Henderson, 1991:457 (part).

Mabuya bistriata — Powell et al., 1996:82 (part).

Mabuya sloanii —Miralles, 2005:49 (part).

Mabuya sloanii — Henderson & Powell, 2009:293 (part).

Holotype. KU 242171, an adult female, collected at North Wells (1.6 km N. Cockburn Town), Grand Turk Island, Turks and Caicos, 28 January 1961, by Albert Schwartz. Original field number AS 10906.

Paratypes (n = 6). Gibbs Cay. KU 242170, Albert Schwartz, 26 March 1972 . Grand Turk Island. ANSP 3835 (no additional collection information available) ; KU 242172–73 , Albert Schwartz , North Wells (1.6 km N. Cockburn Town), 28–30 January 1961 ; MCZ R-11946–47, L. A. Mowbray, no specific locality, June 1916 .

Diagnosis. Spondylurus turksae sp. nov. is characterized by (1) maximum SVL in males, 79.3 mm; (2) maximum SVL in females, 79.1 mm; (3) snout width, 2.42–3.69% SVL; (4) head length, 15.2–16.5% SVL; (5) head width, 12.0–13.0% SVL; (6) ear length, 1.30–1.81% SVL; (7) toe-IV length, 7.05–8.90% SVL; (8) prefrontals, two; (9) supraoculars, four; (10) supraciliaries, four (86%), five (14%); (11) frontoparietals, two; (12) supralabial below the eye, five (67%), six (33%); (13) nuchal rows, two (86%), three (14%); (14) dorsals, 59–63; (15) ventrals, 59–63; (16) dorsals + ventrals, 119–126; (17) midbody scale rows, 30; (18) finger-IV lamellae, 12– 15; (19) toe-IV lamellae, 15–17; (20) finger-IV + toe-IV lamellae, 28–30; (21) supranasal contact, N; (22) prefrontal contact, N; (23) supraocular-1/frontal contact, Y (14%), N (86%); (24) parietal contact, Y; (25) pale middorsal stripe, Y; (26) dark dorsolateral stripe, Y; (27) dark lateral stripe, Y; (28) pale lateral stripe, N (or weak); and (29) palms and soles, pale ( Tables 3–5).

Within the Genus Spondylurus , S. turksae sp. nov. differs from S. anegadae sp. nov., S. culebrae sp. nov., S. haitiae sp. nov., S. monae sp. nov., S. monitae sp. nov., S. semitaeniatus , and S. sloanii by having a wider middorsal stripe (3.51–4.68% SVL versus 0.953–3.32% SVL in those other species) and a lower dark dorsolateral stripe width/middorsal stripe width ratio (0.187 –0.622 versus 0.64–3.79 in those other species; Fig. 79 ). It differs from S. macleani , S. magnacruzae sp. nov., S. martinae sp. nov., S. monitae sp. nov., S. powelli sp. nov., S. sloanii , and S. spilonotus in having fewer midbody scale rows (30 versus 32–34). It differs from S. fulgidus , S. haitiae sp. nov., and S. nitidus in having a shorter toe (toe-IV length 7.05–8.90% SVL versus 9.01–12.9% SVL). It differs from S. haitiae sp. nov., S. martinae sp. nov., and S. monitae sp. nov. in having fewer ventral scales (59–63 versus 64–72). It differs from S. anegadae sp. nov. by lacking supranasal contact (versus supranasals in contact in S. anegadae sp. nov.). It differs from S. caicosae sp. nov. in being larger (three of seven S. turksae sp. nov. > 77.7 mm SVL versus all 99 specimens of S. caicosae sp. nov. <77.6 mm SVL) and in having a higher ear (ear height 1.57–1.87% SVL versus 0.73–1.52% SVL), a wider pale dorsolateral stripe (1.98–2.33% SVL versus 1.02–1.73% SVL), and a dark lateral stripe that is irregular and extends to hindlimbs (versus straight-edged and extends only half-way to hindlimbs). It differs from S. fulgidus in having more dorsal scales (59–63 versus 52–58). It differs from S. haitiae sp. nov. in having a longer ear (ear length 1.30–1.81% SVL versus 1.19% SVL) and fewer dorsals + ventrals (119–126 versus 129–131). It differs from S. lineolatus in having a wider snout (snout width 2.42–3.69% SVL versus 1.97–2.34% SVL), a longer head (head length 15.2–16.5% SVL versus 12.9–14.4% SVL), a wider head (head width 12.0–13.0% SVL versus 9.58–11.6% SVL), more finger-IV lamellae (12–15 versus 8–11), more finger-IV + toe-IV lamellae (28–30 versus 21–26) and fewer dark stripes (four versus 10). It differs from S. nitidus in having a shorter head (head length 15.2–16.5% SVL versus 16.6–20.7% SVL).

Description of holotype ( Figs . 83, 84A–C ). An adult female in good state of preservation, without injuries and with an abdominal slit. SVL 77.8 mm; tail length 74.0 mm (regenerated); HL 11.8 mm; HW 9.47 mm; SW 2.62 mm; EL 1.21 mm; and toe-IV length 6.09 mm; ear-opening average in size and round; toe length in the following order: I <V <II <III <IV.

Head scalation. Rostral wider than high, contacting first supralabials, nasals and supranasals. Paired supranasals not in median contact, contacting anteriormost loreal. Frontonasal diamond-shaped, wider than long, laterally in contact with anterior loreal scale (on the left side only due to anomalous head scale configuration on the right). A pair of quadrilateral prefrontals, separated medially, and in contact with frontonasal, both anterior (left side only) and posterior loreals, first and second supraoculars, and frontal. Frontal heptagonal, in contact with the second supraoculars and paired frontoparietals. Frontoparietals also in contact with parietals and interparietal. Interparietal tetragonal and lanceolate, separated from nuchals by parietals; parietal eye distinct. Parietals in contact with upper secondary and tertiary temporal scales. Four supraoculars (supraoculars three and four fused on the left), the second one being the longest and largest. Four supraciliaries (supraciliaries two and three fused on the left), the second the longest. Nostril in posterior part of the nasal. A small postnasal, bordered by supranasal, anterior loreal and first supralabial. Anterior and posterior loreals squarish with posteromedial projection on latter. Two upper preoculars and two lower preoculars. Seven supralabials, the fifth being the widest and forming the lower border of the eyelid. Six moderately enlarged scales behind eye comprising the postoculars; similar to temporal scales but smaller. One primary temporal, two secondary temporals, and three tertiary temporals; all imbricate, smooth, cycloid, not distinctly delimited from the scales on the nape and the sides of the neck. Seven infralabials. Mental scale wider than long, posterior margin straight. Postmental scale and one pair of adjoining

Body and limb scalation. Two rows of paired nuchal scales and one additional right nuchal scale. Other scales on nape similar to dorsals. On lateral sides of neck, scales slightly smaller. Dorsal scales cycloid, imbricate, smooth, 60 in a longitudinal row; ventrals similar to dorsals; 62 in a longitudinal row; 30 scales around midbody. No distinct boundaries between dorsals, laterals and ventrals. Scales on tail and limbs similar to dorsals, except smaller on limbs. One enlarged dorsal scale row and one enlarged ventral scale row on regenerated tail with rows similar to ventrals on each side. Palmar and plantar regions with small tubercles, subequal in size and delimited by a surrounding region of flatter scales. Subdigital lamellae smooth, single, 14 under finger-IV and 15 under toe-IV. Four preanals larger than adjacent ventral scales. Enlarged median subcaudal scales on tail.

Pattern and coloration. Dorsal ground color medium greenish-brown without dark brown spots. Dark dorsolateral stripes present, narrow (0.69 mm), dark brown, extending from top of head to first third of body. Dark lateral stripes present, dark brown, extending from loreal region to last third of body and breaking into a series of spots around midbody. Pale middorsal stripe present, wide (3.36 mm), medium greenish-brown, extending from top of head to first third of body. Pale dorsolateral stripes present, pale gray, extending from behind eye to first third of body. Pale lateral stripes absent. Ventral surface of body without pattern. Palmar and plantar surfaces unpigmented. No information on color in life of the holotype.

Variation. In coloration and scalation, the other specimens closely resembled the holotype ( Tables 4–5). The forelimbs were mottled with dark brown and hindlimbs had small dark brown spots. The tails of all specimens were pale (orangeish in preservative) distally.

Distribution. This species is distributed on Grand Turk Island (18 km 2) and the adjacent islets of Cotton Cay (see below) and Gibbs Cay ( Fig. 9C ).

Ecology and conservation. No information on the ecology or behavior of this species is available. Grand Turk is a small island that is heavily developed, supporting a relatively large human population (3,720). Most of the island is urbanized, and some large areas are comprised of saline ponds and treeless open areas. Little forest remains, and rats are present on the island. As early as 1916 skinks were reported as being "very rare" on Grand Turk ( Barbour 1916). The last record of this species on Grand Turk was in 1961, and one individual was found on Gibbs Cay, a small islet to the SE of Grand Turk, in 1972. One of us (SBH) was unable to locate the species on Grand Turk during a visit in August, 1999, although the species may still exist on Gibbs Cay. Skinks, probably belonging to this species based on distribution, were observed recently on another islet of Grand Turk, Cotton Cay (R. Graham Reynolds, personal communication). If so, and considering the apparent extirpation of Spondylurus turksae sp. nov. from Grand Turk, these skinks on the small cays of the Turks Bank are the only surviving populations of the species and should be protected.

Based on IUCN Redlist criteria ( IUCN 2011), we consider the conservation status of Spondylurus turksae sp. nov. as Critically Endangered (CR A2ace). It faces a primary threat from habitat alteration by urbanization on Grand Turk Island, and possible development and habitat disturbance on the small cays of Turks Bank where it occurs. The other major threat is predation by introduced mammals, including black rats, in all of these areas. Studies are needed to determine the health of any remaining populations, and threats to the survival of the species. Captive breeding programs should be considered.

Reproduction. No data on reproduction are available for this species.

Etymology. The species name ( turksae ) is a feminine genitive singular noun referring to the distribution of the species in the Turks Islands.

Remarks. The uniqueness of the skinks from the Turks and Caicos Islands has been hinted in earlier work. For example, Barbour (1916) commented on the collection of the two MCZ specimens from Grand Turk and how they differed from typical Spondylurus sloanii in lacking supranasal contact. All other S. turksae sp. nov. that we examined also lack supranasal contact, and that character separates it from a few of the many taxa formerly recognized as S. sloanii . Mayer and Lazell (2000) also noted some pattern differences between skinks of the Turks and Caicos and those of the Puerto Rico region. Conversely, biogeographic connections between the Turks and Caicos fauna and that of the Puerto Rico region have been noted as well ( Thomas & Hedges 2007) and are consistent with the direction of water currents which would have carried animals on flotsam ( Hedges 1996b). Spondylurus turksae sp. nov. has a larger body size and narrower dorsolateral stripes than S. caicosae sp. nov., and the dark lateral stripes extend to the hindlimbs. In these ways it resembles S. nitidus more than S. caicosae sp. nov. SVL in S. nitidus ), and low numbers of midbody scale rows (rarely> 30), suggesting a close relationship. Note added in proof: our DNA sequence analyses indicate a separate origin for S. turksae from the Puerto Rican Bank.

Figures

FIGURE 9. Map showing the distribution of mabuyine skinks occurring on islands in the central, southern, and western Caribbean region. See Fig. 1 for location of the islands. The islands and species are: (A) Jamaica (Spondylurus fulgidus; hollow circle = specimen not examined); (B) Hispaniola (Spondylurus haitiae sp. nov., circle; Mabuya hispaniolae sp. nov., triangle; Spondylurus lineolatus, squares); (C) Turks and Caicos Islands (Spondylurus caicosae sp. nov., circles; Spondylurus turksae sp. nov., triangles; hollow triangle is Cotton Cay record (see text); (D) Margarita (Copeoglossum margaritae sp. nov.); and (E) Roatán (Marisora roatanae sp. nov.).

FIGURE 73. Representative patterns in species of the Genus Spondylurus (top, dorsal view; bottom, side view). (A) S. monitae sp. nov.; (B) S. nitidus; (C) S. powelli sp. nov.; (D) S. semitaeniatus; (E) S. sloanii; (F) S. spilonotus; and (G) S. turksae sp. nov.

FIGURE 79. Graph of pale middorsal stripe width versus dark dorsolateral stripe width in 16 species of the Genus Spondylurus.

FIGURE 83. Head scalation in species of the Genus Spondylurus (left, side view; right, dorsal view). S. turksae sp. nov. (KU 242171, holotype).

FIGURE 84. Spondylurus turksae sp. nov., from the Turks Islands. (A–C) KU 242171, holotype, 1.6 km N Cockburn Town, Grand Turk. (D) KU 242170, paratype, Gibbs Cay.