Spondylurus anegadae, 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 : 139-145

Spondylurus anegadae sp. nov.

Anegada Skink

( Fig. 54A , 55A , 56 )

Mabuya sloanii — Grant, 1937:520 (part).

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

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

Mabuya mabouya sloanei — MacLean et al., 1977:33 (part).

Mabuya mabouya sloanei — Heatwole et al., 1981:34 (part).

Mabuya mabouya — Maclean, 1982:36 (part).

Mabuya sloanei — Lazell, 1983:104 (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 — Mayer & Lazell, 2000:883 (part).

Mabuya sloanii — Perry & Gerber, 2006:244 (part).

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

Holotype. UMMZ 80583 , an adult female, collected 6 April 1936 on Anegada (no specific locality), British Virgin Islands, by Chapman Grant.

Paratypes (n = 37). Anegada, British Virgin Islands. MCZ R-42381 and UMMZ 239502–528 (paratopotypes), same collection data as holotype ; CM 17357–58 , Harry A. Beatty (no additional collection information available) ; KU 242057, Albert Schwartz, vicinity of The Settlement , 18 August 1964 ; KU 242058–63 , Albert Schwartz, The Settlement , 28 March 1968 .

Associated specimens (n = 2). Anegada?, British Virgin Islands. ZMUC-R 759 , A. H. Riise, no specific locality, accessioned in 1862; AMNH R 99522, Harry A. Beatty, Tortola, East-end Hills (probable locality error, see Remarks), 6 November 1966 .

Material not examined (n = 2). Anegada, British Virgin Islands. AMNH R 99523–24, “ Anegada " (no specific locality), collected by Harry A. Beatty.

Diagnosis. Spondylurus anegadae sp. nov. is characterized by (1) maximum SVL in males, 67.8 mm; (2) maximum SVL in females, 70.4 mm; (3) snout width, 2.13–3.34% SVL; (4) head length, 15.4–18.6% SVL; (5) head width, 10.7–13.3% SVL; (6) ear length, 0.96–2.10% SVL; (7) toe-IV length, 8.34–10.7% SVL; (8) prefrontals, two (97%), three (3%); (9) supraoculars, four; (10) supraciliaries, four (95%), five (5%); (11) frontoparietals, two; (12) supralabial below the eye, five (76%), six (24%); (13) nuchal rows, one (5%), two (87%), three (8%); (14) dorsals, 58–66; (15) ventrals, 59–70; (16) dorsals + ventrals, 118–133; (17) midbody scale rows, 28–33; (18) finger-IV lamellae, 10–14; (19) toe-IV lamellae, 13–17; (20) finger-IV + toe-IV lamellae, 24–31; (21) supranasal contact, Y; (22) prefrontal contact, Y (3%), N (97%); (23) supraocular-1/frontal contact, Y (45%), N (55%); (24) parietal contact, Y; (25) pale middorsal stripe, Y; (26) dark dorsolateral stripe, Y; (27) dark lateral stripe, Y; (28) pale lateral stripe, N; and (29) palms and soles, pale ( Tables 3–5).

Within the Genus Spondylurus , S. anegadae sp. nov. is separated from all other species except S. culebrae sp. nov., S. lineolatus , S. monae sp. nov., S. semitaeniatus , and S. sloanii by having a higher dark dorsolateral stripe width/middorsal stripe width ratio (1.35–3.79 versus 0.115–1.27 in those other species). It differs from S. caicosae sp. nov., S. culebrae sp. nov., and S. sloanii by having essentially no dorsal pattern posterior to the dark contact (versus no contact in those other species). From S. magnacruzae sp. nov. and S. spilonotus , it is separated by having a lower number of midbody scale rows (28–33 versus 34 in those other species). Compared with S. culebrae sp. nov. ( maximum SVL , 98 mm), S. anegadae sp. nov. ( maximum SVL , 70.4 mm) is much smaller (e.g., Fig. 2 ) and also differs by a plot of interparietal width versus SVL ( Fig. 57 ). From S. lineolatus , it differs by having two dark dorsolateral stripes and two dark lateral stripes (versus 10 dark stripes in S. lineolatus ) and by having a larger head (head length 15.4–18.6% SVL versus 12.9–14.4% in S. lineolatus ). Spondylurus anegadae sp. nov. differs from S. semitaeniatus by having a shorter, wider nostril (Fig. 58). It differs 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.). In pattern ( Fig. 55A ), S. anegadae sp. nov. differs most distinctively from other species in having a pale face (top and side of snout) and dark dorsolateral and lateral stripes that extend only a short distance past the axila and then end abruptly, the dorsolateral stripes being distinctly darker than lateral stripes.

Besides those non-overlapping differences, there are frequency differences that distinguish Spondylurus anegadae sp. nov. from other species. It differs from S. fulgidus by having fewer supraciliaries (four in 95% of specimens versus five in S. fulgidus ). It is separated from S. haitiae sp. nov. by having a larger ear (ear length 1.26– 2.10% SVL in 88% of specimens versus 1.19% in S. haitiae sp. nov.). It is distinguished from S. macleani by having fewer finger-IV + toe-IV lamellae (24–29 in 86% of specimens versus 30–31 in 80% of specimens belonging to S. macleani ). It is separated from S. martinae sp. nov. by having fewer ventral scales (59–67 in 94% of specimens versus 68–71 in S. martinae sp. nov.). It differs from S. monae sp. nov. by having a higher dark dorsolateral stripe width/middorsal stripe width ratio (1.82–3.79 in 85% of specimens versus 0.985–1.73 in 89% of specimens belonging to S. monae sp. nov.). It is distinguished from S. nitidus by having a shorter toe-IV (toe-IV length 8.34–10.0% SVL in 81% of specimens versus 10.1–12.7% SVL in 93% of specimens belonging to S. nitidus ). From S. powelli sp. nov., it is separated by having supranasal contact (versus no supranasal contact in 81% of specimens belonging to S. powelli sp. nov.). It is separated from S. sloanii by lacking prefrontal contact: no contact in 97% of specimens of S. anegadae sp. nov. versus contact (or near contact; <0.3% SVL separation of prefrontals), in 74% of specimens belonging to S. sloanii ). Approximately one-half of S. anegadae sp. nov. have 30 or fewer midbody scale rows, but other species of the genus Spondylurus inhabiting the Virgin Islands ( S. macleani , S. magnacruzae sp. nov., S. semitaeniatus , S. sloanii , and S. spilonotus ) all have 31 or more scale rows. Except for S. lineolatus and S. powelli sp. nov., Spondylurus anegadae sp. nov. is a smaller species than all others within the Genus Spondylurus (maximum adult SVL 70.4 mm versus 77.6–98.8 mm in other species).

Description of holotype ( Figs. 54A , 56A–C ). An adult female in good state of preservation, without injuries and with an abdominal slit. SVL 67.0 mm; tail length 95.8 mm (complete); HL 10.3 mm; HW 7.16 mm; SW 1.43 mm; EL 1.06 mm; and toe-IV length 5.59 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 in median contact, contacting anteriormost loreal. Frontonasal tetragonal, 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 (fused in holotype), first supraciliary, first supraoculars, and frontal. Frontal heptagonal, elongate, in contact with the first and second supraoculars and paired frontoparietals. Frontoparietals also in contact with parietals and interparietal. Interparietal tetragonal and acorn-shaped, separated from nuchals by parietals; parietal eye distinct. Parietals in contact with upper secondary and tertiary temporal scales. Four supraoculars, the second one being the largest. Four supraciliaries, 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 fused (rectangular) with posterodorsal projection. One upper and two lower preoculars. Seven supralabials, the fifth being the widest and forming the lower border of the eyelid. Three moderately enlarged postocular scales behind eye; 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. Six infralabials. Mental scale wider than long, posterior margin straight. Postmental scale and one pair of 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. Two rows of nuchal scales, paired. Other scales on nape similar to dorsals. On lateral sides of neck, scales slightly smaller. Dorsal scales cycloid, imbricate, smooth, 64 in a longitudinal row; ventrals similar to dorsals; 64 in a longitudinal row; 32 scales around midbody. No distinct boundaries between dorsals, laterals and ventrals. Scales on tail and limbs similar to dorsals, except smaller on limbs. Palmar and plantar regions with small tubercles, subequal in size and delimited by a surrounding region of flatter scales. Subdigital lamellae smooth, single, 12 under finger-IV and 16 under toe-IV. Four preanals larger than adjacent ventral scales. No enlarged median subcaudal scales on tail.

Pattern and coloration. Dorsal ground color pale greenish-gray with only a few small dark spots or flecks, paler on top and sides of head and neck. Dark dorsolateral stripes present, wide (2.13 mm), dark brown, extending from top of head to first third of body. Dark lateral stripes present, tan, irregular (series of close blotches), extending from behind eye to first third of body. Pale middorsal stripe present, narrow (1.02 mm), bluish-white, extending from top of head to first third of body. Pale dorsolateral stripes present, bluish-white, extending from behind eye to first third of body. Pale lateral stripes absent. Forelimbs and hindlimbs slightly darker brown. Ventral surface of body without pattern except for fine tan flecks (on magnification) giving appearance of a slight gray tinge. Palmar and plantar surfaces unpigmented. No information on color in life is available on the holotype.

Variation. In coloration and scalation, other specimens resembled the holotype ( Tables 4–5). Carey (1972) mentioned that color in life was red-brown with a uniform cream venter, and MacLean (1982) noted that the dorsum was "shiny, metallic bronze." In the field notes of Albert Schwartz, KU 242058–061 were described in life as having "head brown; supraorbitals white, extending to tympanum as stripe; infralabials and gular region white. A brown stripe extends back nearly to midbody; also two chocolate stripes beginning on top of head above the eye and extending back nearly to midbody. Dorsum reddish brown; lighter on tail; sides same as dorsum. Venter uniform cream, mid-tail, forelimbs, and hindlimbs slightly darker brown." The greenish tinge of all of the UMMZ specimens contrasts strongly with the absence of any green mentioned for color in life, indicating that the greenish tinge is a preservational artifact.

Distribution. The species is distributed on Anegada, British Virgin Islands ( Fig. 10F ) ( Carey 1972; MacLean et al. 1977; MacLean 1982; Lazell 1983; Schwartz & Henderson 1991; Perry & Gerber 2006). The only specific locality that has been reported is The Settlement.

Ecology and conservation. No new information on this species has been reported since Carey (1972), who noted that "these skinks seemed to reach their greatest abundance in forested limestone areas amongst rock piles accumulated by the natives. They were occasionally seen basking on these piles" and "they were rarely found in trash piles." Several individuals examined contained nematodes and cysts in their body cavities. Maclean (1982) found one individual among loose piles of dry coral that comprised the foundation of a house in The Settlement on Anegada (no date of collection was reported). He kept it in captivity, where it ate insects and ground beef from his hand. Introduced domestic mammals are almost certainly a threat to the survival of Spondylurus anegadae sp. nov., threatened by rising sea levels in coming decades as a result of global warming. The most recent sighting of Spondylurus anegadae sp. nov. was in the late 1990s (J. D. Lazell, personal communication).

Based on IUCN Redlist criteria ( IUCN 2011), we consider the conservation status of Spondylurus anegadae sp. nov. to be Critically Endangered (CR A2ace). It faces a primary threat from predation by introduced mammals, including black rats, and a secondary threat from habitat alteration. 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 considered, if the species still exists.

Reproduction. Seven females with the following SVLs (mm) contained 1–2 (mean = 1.7) developing young: 54.5 (two young), 57.8 (two), 58.9 (one), 62.7 (two), 63.0 (one), 66.5 (two), and 68.2 (two). At least three other females (61.8–66.1 mm SVL) had recently given birth. The largest fetus was 28 mm SVL. Considering that the smallest juvenile measured was 30.9 mm SVL, the young of Spondylurus anegadae sp. nov. are approximately 28– 30 mm SVL at birth. The date of collection for all of those specimens was 6 April 1936.

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

Remarks. The earliest specimen collected was ZMUC-R 759, obtained by the Danish pharmacist Albert Heinrich Riise, with no specific locality ("West Indies"). We treat it as an associated specimen because, although it agrees mostly with S. anegadae sp. nov. in scalation and size, the dark dorsolateral stripes are narrower than typical members of that species. Although Riise's pharmacy was located on St. Thomas, he was known to travel widely in the Greater Puerto Rico Region in his collecting activities ( Schmidt 1928).

Grant (1937) was the first to report this genus on Anegada, and most of the museum specimens were collected by him. He immediately noticed that they differed in color and size from skinks that he collected on other islands in the Puerto Rico region and sent them to Helen Gaige (UMMZ) for her opinion. She concurred but could not find other differences ( Grant 1937). The size and pattern differences are striking ( Fig. 2 ), but we also identified scale differences, as noted above. No tissues were available for molecular phylogenetic analysis, but details of the color pattern (e.g., short dark dorsolateral stripes) suggest a relationship with a species distributed nearby in the U.S. and British Virgin Islands, recognized here as S. semitaeniatus (see below).

Spondylurus anegadae sp. nov. is the only skink species known from Anegada, and we have not identified specimens of this species from any other islands, except associated specimen AMNH R99522, collected in 1966 by Beatty on Tortola (East-end Hills). The specimen is quite damaged from being shot, but it has the typical characters (of those that can be scored) of S. anegadae sp. nov. and not S. semitaeniatus , the only species known from Tortola. For example, it has 30 midbody scale rows (not found in S. semitaeniatus , common in S. anegadae sp. nov.), supraciliary-prefrontal contact (rare in S. semitaeniatus , common in S. anegadae sp. nov.), and pattern characteristics of S. anegadae sp. nov. (very short dorsal stripes, pale snout, virtually no dorsal spotting). Because specimens of S. anegadae sp. nov., collected by Beatty from Anegada (AMNH R99523–24), immediately follow this specimen numerically, it is likely that there was a mix-up in specimen number and locality when the specimen was cataloged (or earlier). Thus, we consider AMNH R99522 to have an incorrectly labeled locality and that it likely came from Anegada.

Only slight ontogenetic change was observed in coloration. Fetuses look identical to adults except that the dark brown dorsolateral stripes extend to the tip of the snout, and pale lateral stripes (absent in adults) are visible ( Fig. 56D ). In the smallest juvenile (UMMZ 239525; 30.9 mm SVL), the snout tip stripe is present but reduced, whereas the adult pattern is present in a slightly larger juvenile (UMMZ 239522; 33.7 mm SVL).

Figures

FIGURE 2. Preserved museum specimens of adult male and female skinks from two islands on the Puerto Rican Bank, Culebra (left; Spondylurus culebrae sp. nov.) and Anegada (right; S. anegadae sp. nov.), currently considered to be the same species, "Mabuya" sloanii. Note consistent difference in coloration and body size (S. culebrae sp. nov. = 98 mm SVL, S. anegadae sp. nov. = 70 mm SVL, maximums). Females from both islands, shown here, contain developing young. All were collected by Chapman Grant in the 1930s and are in the collection of the University of Michigan, Museum of Zoology.

FIGURE 10. Map showing the distribution of mabuyine skinks occurring on islands in the greater Puerto Rico region. See Figure 1 for location of the islands. The islands and species are: (A) Puerto Rico (Spondylurus nitidus); (B) Mona (Spondylurus monae sp. nov., squares) and Monito (Spondylurus monitae sp. nov., circle); (C) Desecheo (Spondylurus nitidus); (D) Vieques (Spondylurus nitidus, circle), Culebra (Spondylurus nitidus, circles; Spondylurus culebrae sp. nov., squares), Cayo Luis Peña and Cayo Norte (S. nitidus, circles); (E) most of the U.S. and British Virgin Islands (Spondylurus macleani, diamond; Spondylurus sloanii, squares; Spondylurus semitaeniatus, circles; Spondylurus spilonotus, triangles); (F) Anegada (Spondylurus anegadae sp. nov.); and (G) St. Croix and Green Cay (Capitellum parvicruzae sp. nov., circle; Spondylurus magnacruzae sp. nov.,

FIGURE 54. Head scalation in species of the Genus Spondylurus (left, side view; right, dorsal view). (A) S. anegadae sp. nov. (UMMZ 80583, holotype); (B) S. caicosae sp. nov. (AMNH R-80126, holotype); (C) S. culebrae sp. nov. (UMMZ 73823,

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 56. Spondylurus anegadae sp. nov., from Anegada, British Virgin Islands. (A–C) UMMZ 80583, holotype, Anegada (no specific locality). (D) fetus of UMMZ 239508.

FIGURE 57. Graph of interparietal width versus snout-vent length in two species of the Genus Spondylurus.