Spondylurus monitae, 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 : 182-186

Spondylurus monitae sp. nov.

Monito Skink

( Figs. 70C , 73A , 74 )

Mabuya mabouya sloanii — Rolle et al., 1964:322 (part).

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

Mabuya mabouya sloanei — MacLean et al., 1977:27 (part).

Mabuya mabouya sloanei — Heatwole et al., 1981:34 (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 — Henderson & Powell, 2009:293 (part).

Holotype. USNM 576301 , an adult female, collected on Isla Monito, Puerto Rico, United States, 12–13 February 1993, by Manuel Leal and Richard Thomas. Field tag USNMFS 192877.

Paratypes (n = 6). Isla Monito , Puerto Rico. RT 11377–79, 11427, Manuel Leal and Richard Thomas, 3–4 April 1993 ; RT 11391, Miguel Garcia , Manuel Leal, and Richard Thomas, 13–14 April 1993 ; and RT 11430, Richard Thomas , November 1993 .

Diagnosis. Spondylurus monitae sp. nov. is characterized by (1) maximum SVL in males, 90.3 mm; (2) maximum SVL in females, 94.5 mm; (3) snout width, 2.42–3.16% SVL; (4) head length, 16.2–17.8% SVL; (5) head width, 11.5–13.8% SVL; (6) ear length, 1.35–1.59% SVL; (7) toe-IV length, 8.34–10.7% SVL; (8) prefrontals, two; (9) supraoculars, three (43%), four (57%); (10) supraciliaries, three (29%), four (43%), five (29%); (11) frontoparietals, two; (12) supralabial below the eye, five; (13) nuchal rows, two; (14) dorsals, 62–64; (15) ventrals, 64–69; (16) dorsals + ventrals, 126–132; (17) midbody scale rows, 32–34; (18) finger-IV lamellae, 12–15; (19) toe-IV lamellae, 16–17; (20) finger-IV + toe-IV lamellae, 29–32; (21) supranasal contact, N; (22) prefrontal contact, N; (23) supraocular-1/frontal contact, Y (86%), N (14%); (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. monitae sp. nov. is separated from all other species by having concave (versus parallel) dark dorsolateral stripes on the parietal scales, forming a constriction on the top of the head ( Fig. 73A ). It differs from S. caicosae sp. nov., S. fulgidus , S. haitiae sp. nov., S. magnacruzae sp. nov., S. martinae sp. nov., S. nitidus , S. powelli sp. nov., S. spilonotus , and S. turksae sp. nov. by having a higher dark dorsolateral stripe width/middorsal stripe width ratio (0.874–1.27 versus 0.115 –0.805 in those other species). It differs from S.

anegadae sp. nov. and S. semitaeniatus by having a lower dark dorsolateral stripe width/middorsal stripe width ratio (0.874–1.27 versus 1.35–3.79 in those other species). It differs from S. lineolatus and S. turksae sp. nov. by having more midbody scale rows (32–34 versus 26–30). From S. anegadae sp. nov., it differs by lacking supranasal contact (versus contact in S. anegadae sp. nov.). It differs from S. lineolatus by having a longer head (head length 16.2–17.8% SVL versus 12.9–14.4% in S. lineolatus ). It is distinguished from S. macleani by having lateral dark and pale stripes. From S. monae sp. nov., it differs by having a higher rostral scale ( Fig. 61 ). Spondylurus monitae sp. nov. further differs from S. monae sp. nov. in being larger: four of the six adult specimens are larger (88.5–94.5 mm SVL) than all of the 35 specimens of S. monae sp. nov. examined (87.0 mm SVL, maximum).

Spondylurus monitae sp. nov. also differs from other species in slightly overlapping characters. From S. culebrae sp. nov., S. magnacruzae sp. nov., S. monae sp. nov., and S. spilonotus , it is distinguished by having fewer supralabials (supralabial five below the eye versus supralabial six or seven below the eye in 84–91% of specimens belonging to those other species). From S. nitidus , it differs by having a higher frequency of supraocular-1/frontal contact (contact in 86% of specimens versus no contact in 93% of specimens belonging to S. nitidus ). It is separated from S. semitaeniatus and S. sloanii by lacking supranasal contact (versus contact in 95– 96% of specimens belonging to those other species).

Description of holotype ( Figs. 70C , 74 ). An adult female in excellent state of preservation, without injuries and with an abdominal slit. SVL 89.3 mm; tail length not measured (complete); HL 15.3 mm; HW 11.3 mm; SW 2.45 mm; EL 1.34 mm; and toe-IV length 7.97 mm; ear-opening small 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 supraoculars, first supraciliary (right side only), and frontal. Frontal mostly tetragonal and shield-shaped, 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; parietal eye distinct. Parietals in contact with upper secondary and supralabial. Anterior loreal squarish and posterior loreal rectangular with posterodorsal projection on latter. One upper preocular and two lower preoculars. Seven supralabials, the fifth being the widest and forming the lower border of the eyelid. Three 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 with a small scale between infralabials six and seven on right. Mental scale wider than long, posterior margin straight. Postmental scale and one pair of adjoining chin shields in contact with anterior infralabials. First two pairs of chin shields in contact medially; third pair separated by a smaller cycloid scale.

Body and limb scalation. Two rows of nuchal scales, both paired. Other scales on nape similar to dorsals. On lateral sides of neck, scales slightly smaller. Dorsal scales cycloid, imbricate, smooth, 63 in a longitudinal row; ventrals similar to dorsals; 69 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. 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 17 under toe-IV. Four preanals larger than adjacent ventral scales. No enlarged median subcaudal scales on tail.

Pattern and coloration. Dorsal ground color medium grayish-green with small dark brown spots uniformly distributed on body. Dark dorsolateral stripes present, narrow (2.19 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. Pale middorsal stripe present, wide (2.51 mm), grayish-green, extending from tip of snout to first third of body. Pale dorsolateral stripes present, whitish-blue, extending from loreal region to midbody. Pale lateral stripes present, whitish-blue, extending from loreal region to last third of body, not bordered below by a narrow dark line. Forelimbs pale blue and hindlimbs medium gray-green, all with small brown spots on dorsal surfaces and without pattern on ventral surfaces. Ventral surface of body without pattern except for small brown spots. Palmar and plantar surfaces unpigmented. No information is available on color of the holotype in life.

Variation. In coloration and scalation, the paratypes resembled the holotype ( Tables 4–5).

Distribution. The species is distributed on Monito Island, 0.147 km 2 ( Fig. 10B ). The highest elevation on the island is 63 m.

Ecology and conservation. No ecological information is available for this species. Monito Island is a very small, uninhabited island located about 5 km NW of Mona Island. It is similar to Mona in being a raised limestone block and flat-topped, although vegetation is more limited in diversity. It has been described as xeric scrub vegetation consisting primarily of cacti, shrubs, and stunted trees growing from cracks in the limestone ( Rolle et al. 1964). As with Mona, it is a Natural Reserve administered by the Puerto Rico Department of Natural Resources. The mongoose is not present on Monito. Black rats were present until the 1990s, at which time concern was expressed that they were responsible for declines in the endemic gecko population ( Sphaerodactylus micropithecus Schwartz ). An eradication program for the black rat was successful ( Garcia et al. 2002).

One threat to the survival of Spondylurus monitae sp. nov. is from human disturbance, now at an all-time high. Monito Island is being used by immigrants, especially Cubans (passing through Hispaniola), who use it (and Mona Island) as a point of first contact on U.S. soil (see "Ecology and Conservation" for S. monae sp. nov.). In 2010– 2011, dozens of immigrants claimed Monito as home until they were rescued by the U.S. Coast Guard. Typically, a dozen persons will stay on the small island at one time, often over one or more nights, until they are picked up by the Coast Guard. Presumably some habitat is disturbed, and perhaps campfires are built with some of the few trees on the island. This also raises the possibility that black rats could be brought to the island, unintentionally, on those boats carrying immigrants. A reintroduction of black rats could be devastating for the populations of endemic lizard species. At the time of this writing, nothing is being done to prevent these activities, and it is not known how much disturbance is taking place and its effects on the biodiversity.

Based on IUCN Redlist criteria ( IUCN 2011), and because of this threat and small area of the island, we assess the conservation status of Spondylurus monitae sp. nov. to be Critically Endangered (CR A2ace). It, and Sphaerodactylus micropithecus , both face a primary threat from the potential introduction of invasive predators (black rats) as a result of unauthorized human activities on the island, and a major secondary threat from habitat alteration as a result of those same activities. Studies are needed to determine if the species still exists, the health of

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

Etymology. The species name ( monitae ) is a feminine genitive singular noun referring to the distribution of the species on the island of Monito (it is feminine despite the masculine diminutive Spanish island name).

Remarks. The first mention of a skink from Isla Monito was a sighting of a single specimen by Rolle et al. (1964). We have been unable to locate additional specimens of the species besides the seven examined here, all collected in 1993. It is remarkable that the small island of Monito supports an endemic species of skink ( Spondylurus monitae sp. nov.), distinct from the species inhabiting the nearby island of Mona ( S. monae sp. nov.). Besides non-overlapping scale and pattern differences, S. monitae sp. nov. is significantly larger than S. monae sp. nov. Based on morphology we suspect that the skinks from Mona and Monito may have been independently derived from Puerto Rico and are not closest relatives.

Figures

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 61. Graph of rostral height versus rostral length in seven species of the Genus Spondylurus.

FIGURE 70. Head scalation in species of the Genus Spondylurus (left, side view; right, dorsal view). (A) S. martinae 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 74. Spondylurus monitae sp. nov., from Monito Island, Puerto Rico. (A–B) USNM 576301, holotype, Isla Monito (no specific locality). (C) USNM 576301, holotype (live individual, photographed by S. B. Hedges).