Spondylurus martinae, 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 : 174-178

Spondylurus martinae sp. nov.

Saint Martin Skink

( Figs. 55I , 70A , 71 )

Mabuya mabouia — Barbour, 1935:129 (part).

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

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

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

Mabuya mabouya mabouya — MacLean et al., 1977:36 (part).

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

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

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

Holotype. MCZ R-86418, an adult female, collected in the vicinity of Little Bay , St. Martin, by G. A. Scamon (no other data). Date of accession, 1965.

Paratypes (n = 8). St. Martin. MCZ R-86419 (paratopotype), same collection data as holotype ; ANSP 9503– 07 and 9414–15, collected by H. E. Rijgersma, no specific locality, date unrecorded, but probably 1863–77 (see Remarks) .

Diagnosis. Spondylurus martinae sp. nov. is characterized by (1) maximum SVL in males, not available; (2) maximum SVL in females, 83.1 mm; (3) snout width, 2.15–2.78% SVL; (4) head length, 15.0–17.1% SVL; (5) head width, 9.97–12.3% SVL; (6) ear length, 1.27–1.93% SVL; (7) toe-IV length, 8.22–10.5% SVL; (8) prefrontals, two; (9) supraoculars, three (78%), four (22%); (10) supraciliaries, four; (11) frontoparietals, two; (12) supralabial below the eye, five (56%), six (44%); (13) nuchal rows, one (20%), two (40%), three (40%); (14) dorsals, 56–65; (15) ventrals, 68–71; (16) dorsals + ventrals, 124–133; (17) midbody scale rows, 32–34; (18) finger-IV lamellae, 13–17; (19) toe-IV lamellae, 15–19; (20) finger-IV + toe-IV lamellae, 28–36; (21) supranasal contact, Y (11%), N (89%); (22) prefrontal contact, Y (11%), N (89%); (23) supraocular-1/frontal contact, Y (67%), N (33%); (24) parietal contact, Y; (25) pale middorsal stripe, Y; (26) dark dorsolateral stripe, Y; (27) dark lateral stripe, Y; (28) pale lateral stripe, Y; and (29) palms and soles, pale ( Tables 3–5).

Within the Genus Spondylurus , S. martinae sp. nov. differs from S. anegadae sp. nov., S. culebrae sp. nov., S. haitiae sp. nov., S. monae sp. nov., S. monitae sp. nov., and S. semitaeniatus by having a narrower dark dorsolateral stripe (1.86–2.09% SVL versus 2.12–4.64% SVL in those other species). It is separated from S. fulgidus , S. lineolatus , S. macleani , S. nitidus , S. powelli sp. nov., and S. turksae sp. nov. by having a higher number of ventral scales (68–71 versus 55–67 in those other species). It is distinguished from S. anegadae sp. nov., S. monae sp. nov., S. semitaeniatus , and S. sloanii by having a wider middorsal stripe (2.76–4.01% SVL versus 0.953–2.62% SVL in those other species). It is distinguished from S. magnacruzae sp. nov. and S. spilonotus by having a higher dark dorsolateral stripe width/middorsal stripe width ratio (0.500 –0.742 versus 0.276 –0.464 in those other species). From S. nitidus , it differs by having a narrower head (head width 9.97–12.3% SVL versus 12.5–14.6% SVL in S. nitidus ). From S. fulgidus , it differs by having a lower number of supraciliaries (four versus five in S. fulgidus ). From S. haitiae sp. nov., it differs by having a larger ear (ear length 1.27–1.93% SVL versus 1.19% in S. haitiae sp. nov.). It is separated from S. lineolatus by having a higher number of finger-IV lamellae (13–17 versus 8–11 in S. lineolatus ). From S. turksae sp. nov., it differs in having more midbody scale rows (32–34 versus 30). It is distinguished from S. monitae sp. nov. by having straighter dark dorsolateral stripes (versus dark dorsolateral stripes that bow inward on the parietal scales in S. monitae sp. nov.).

Frequency differences also separate Spondylurus martinae sp. nov. from other species within the genus. From S. anegadae sp. nov., S. culebrae sp. nov., S. semitaeniatus , and S. sloanii , it differs by having a lower frequency of supranasal contact (no contact in 89% of specimens versus supranasal contact in 80–100% of specimens belonging to those other species). It differs from S. monae sp. nov. and S. nitidus by having a shorter head (head length 15.0– 17.1% SVL versus 17.3–20.7% in 83–86% of specimens belonging to those other species). It is distinguished from S. caicosae sp. nov. by having a higher number of ventral scales (68–71 versus 56–65 in 95% of specimens belonging to S. caicosae sp. nov.) and by having a higher number of midbody scale rows (32–34 versus 27–31 in 94% of specimens belonging to S. caicosae sp. nov.). From S. powelli sp. nov., it differs by having a higher number of finger-IV + toe-IV lamellae (30–36 in 89% of specimens versus 25–29 in 94% of specimens belonging to S. powelli sp. nov.).

Description of holotype ( Fig. 71 ). An adult female in good state of preservation, with injuries and with an abdominal slit. SVL 83.1 mm; tail length 50.1 mm (regenerated and broken); HL 12.8 mm; HW 10.2 mm; SW 1.79 mm; EL 1.60 mm; and toe-IV length 6.83 mm; ear-opening large in size and oval; 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. A pair of quadrilateral prefrontals, separated medially, and in contact with frontonasal, both anterior and posterior loreals, first supraciliary, first supraoculars, and frontal. Frontal hexagonal, in contact with the first and second supraoculars and paired frontoparietals. Frontoparietals also in contact with parietals and interparietal. Interparietal tetragonal and lanceolate, separated from nuchals by parietals; nasal. A small postnasal, bordered by supranasal, anterior loreal and first supralabial. Anterior and posterior loreals rectangular except right posterior loreal, which is squarish with a posteromedial projection. Two upper preoculars and two lower preoculars. Eight supralabials, the sixth being the widest and forming the lower border of the eyelid. Five moderately enlarged scales behind eye comprising the postoculars; similar to temporal scales but smaller (except the primary postocular, which is similar in size to temporal). 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 zero pairs of adjoining chin shields in contact with anterior infralabials. First pair of chin shields in contact medially; second pair separated by a smaller cycloid scale.

Body and limb scalation. One row of paired nuchal scales and one additional left nuchal. Other scales on nape similar to dorsals. On lateral sides of neck, scales slightly smaller. Dorsal scales cycloid, imbricate, smooth, 65 in a longitudinal row; ventrals similar to dorsals; 68 in a longitudinal row; 34 scales around midbody. No distinct boundaries between dorsals, laterals and ventrals. Scales on tail and limbs similar to dorsals, except smaller on limbs. On regenerated portion of tail, one row each of enlarged middorsal and midventral scales with lateral rows on each side similar to dorsals and ventrals. Palmar and plantar regions with small tubercles, subequal in size and delimited by a surrounding region of flatter scales. Subdigital lamellae smooth, single, 13 under finger-IV and 15 under toe-IV. Six preanals similar to ventrals. Enlarged median subcaudal scales on regenerated portion of tail.

Pattern and coloration. Dorsal ground color medium brownish-green with small dark brown spots, distributed on body (mostly posterior to the forelimbs), tail, and limbs. Dark dorsolateral stripes present, narrow (1.70 mm), irregular, dark brown, extending from top of head to first third of body. Dark lateral stripes present, dark brown with small pale spots, extending from loreal region to midbody and fading from midbody to hindlimbs. Pale to midbody. Pale lateral stripes present, whitish-green, extending from behind ear to forelimbs, bordered below (anterior of forelimbs) by a narrow, dark, broken line (row of spots). Ventral surface of body without pattern. Palmar and plantar surfaces unpigmented. No information is available on color in life in the holotype.

Variation. Most specimens resembled the holotype ( Tables 3–5), except that the pattern on the older ( ANSP) specimens had faded somewhat and could not be discerned on the heads (dorsal surface) of juveniles. Nonetheless, and typical of juveniles and fetuses of mabuyines, the body stripes on the juveniles appear bolder than on the adults. In this case, the dark lateral stripes extend to the hindlimbs .

Distribution. The species is distributed on St. Martin, where it is known only from Little Bay, although it is assumed to have been island-wide when extant ( Fig. 11A ).

Ecology and conservation. The date of collection of the MCZ holotype and paratype is not known, but they were accessioned in 1965. Aside from those specimens, the only other ones that we could locate were collected in 1863–1877, prior to the introduction of the mongoose in 1885–1889 ( Horst et al. 2001). The 20th century specimens are promising, but recent authors have suggested that skinks have been extirpated from the island because they have not been seen or collected in decades ( Breuil 2002; Powell 2006). Skinks are considered to be common on the nearby islands of the same bank, Anguilla ( Hodge et al. 2003) and St. Barts ( Breuil 2002). This is almost certainly because the mongoose is absent from those islands.

Based on IUCN Redlist criteria ( IUCN 2011), we assess the conservation status of Spondylurus martinae sp. nov. to be Critically Endangered, and possibly extinct (CR A2ace). It faces a primary threat from the introduced mongoose, which has probably led to its extinction. Secondary threats include habitat destruction from agriculture and urbanization, and predation from other introduced mammals, including black rats. Studies are needed to determine if the species still exists, the health of any remaining populations, and threats to the survival of the species. Captive breeding programs should be undertaken, if the species still exists, because eradication of introduced mammalian predators is not possible on an island as large as St. Martin.

Reproduction. No data on reproduction are available for this species. However, the five juveniles ( ANSP 9503–07 ), collected by Rijgersma, are all similar in size (39.2–41.5 mm SVL), suggesting that they share the same mother .

Etymology. The species name ( martinae ) is a feminine genitive singular noun referring to the distribution of the species on the island of St. Martin.

Remarks. No additional information is available on the holotype and MCZ paratype. The donor and probable collector of the ANSP paratypes, Hendrik E. van Rijgersma (1835–1877), was a Dutch naturalist and physician who practiced medicine on St. Martin during 1863–1877 ( Holthius 1959). He collected plants and animals and sent the latter to the Academy of Natural Sciences, Philadelphia. They were received by E. D. Cope, who acknowledged the collection ( Holthius 1959). No collection information is associated with those ANSP specimens, other than the island and the donor, and therefore the date of collection is constrained to Rijgersma's time on the island, 1863– 1877. Dunn mentioned these ANSP specimens in the first sentence of his revision of "American Mabuyas" ( Dunn 1936): "the following notes are an attempt to name Mabuyas from the islands of St. Martin, Redonda, and Marie Galante, in the collection of the Academy."

Dunn (1936) considered skinks from St. Martin, part of the Anguilla Bank in the northern Lesser Antilles, to be intermediate between his races of Mabuya mabouya . He did this because of the presence of dark dorsolateral stripes (a " M. mabouya sloanii " character) and a combination of characters from that race and " M. m. mabouya " (three and four supraoculars, one and multiple nuchal rows). However, supraoculars are frequently variable in species, and our counts of nuchals indicate a higher proportion of specimens of S. martinae sp. nov. with multiple rows of nuchals. Although no DNA data are available, the bold dorsolateral stripes (dark and pale) of S. martinae sp. nov. place that species in the Genus Spondylurus . The smaller maximum body size (83 mm SVL versus ~ 100 mm SVL in species of the Genus Mabuya ) and presence of multiple nuchals in most specimens of S. martinae sp. nov. further support its placement in the Genus Spondylurus . Subsequent researchers have interpreted Dunn's (1936) remarks differently, leading to some confusion over what skinks actually occur in the northern Lesser Antilles and whether they are sympatric or not (see Remarks for the genus Mabuya for discussion).

Figures

FIGURE 11. Map showing the distribution of mabuyine skinks occurring in the Lesser Antilles and Trinidad and Tobago. See Fig. 1 for location of the islands. The islands and species are: (A) Anguilla, Dog Island, and St. Barts (Spondylurus powelli sp. nov., squares), and St. Martin (S. martinae sp. nov., circle); (B) Guadeloupe: Basse-Terre (Mabuya guadeloupae sp. nov., square), Grande-Terre (Mabuya grandisterrae sp. nov., triangle), Îlet à Cochons (Mabuya cochonae sp. nov., star), La Désirade and Terre de Bas, Petite-Terre (Mabuya desiradae sp. nov., diamonds), and Marie-Galante (Capitellum mariagalantae sp. nov., circle); (C) Martinique (Mabuya mabouya, circles; Capitellum metallicum, triangle); (D) St. Vincent, the Grenadines, and Grenada (Copeoglossum aurae sp. nov., circles; Marisora aurulae sp. nov., triangles); (E) Redonda (Copeoglossum redondae sp. nov., circle) and Montserrat (Mabuya montserratae sp. nov., square); (F) Dominica (Mabuya dominicana); (G) St. Lucia (Alinea luciae), (H) Barbados (Alinea lanceolata); (I) Trinidad (Copeoglossum aurae sp. nov., circles; Marisora aurulae sp. nov., triangle), and (J) Tobago (Copeoglossum aurae sp. nov., circles; Marisora aurulae sp. nov., triangles). Hollow symbols in A and J are literature records (specimens not examined). Where no specific localities within an island are known for a species, a symbol is placed centrally on the island: Alinea luciae, Capitellum mariagalantae, Capitellum metallicum, and Copeoglossum redondae sp. nov. The scale in (A) applies to all islands.

FIGURE 55. Representative patterns in species of the Genus Spondylurus (top, dorsal view; bottom, side view). (A) S. anegadae sp. nov.; (B) S. caicosae sp. nov.; (C) S. culebrae sp. nov.; (D) S. fulgidus; (E) S. haitiae sp. nov.; (F) S. lineolatus; (G) S. macleani; (H) S. magnacruzae sp. nov.; (I) S. martinae sp. nov.; and (J) S. monae sp. nov.

FIGURE 70. Head scalation in species of the Genus Spondylurus (left, side view; right, dorsal view). (A) S. martinae sp. nov.

FIGURE 71. Spondylurus martinae sp. nov., from St. Martin. (A–D) MCZ R-86418, holotype, Little Bay.