Spondylurus nitidus ( Garman 1887 ) Hedges, S. Blair & Conn, Caitlin E., 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 : 186-190

Spondylurus nitidus ( Garman 1887) comb. nov.

Puerto Rican Skink

( Figs. 70D , 73B , 75 )

Mabuya fulgida — Cope, 1868:311 (part).

Euprepes (Mabuia) spilonotus — Peters, 1876:708 (part).

Mabuia nitida — Garman, 1887:51. Lectotype: MCZ R-6050, San Juan , Puerto Rico, April 1879, Samuel Garman.

Mabuia sloanii — Boulenger, 1887:193 (part).

Mabuya sloanii — Stejneger, 1904:608 (part).

Mabuya sloanii — Barbour, 1914:320 (part).

Mabuya sloanii — Schmidt, 1928:121 (part).

Mabuya sloanii — Schmidt, 1928:121 (part; syntype from Hispaniola removed from type series of Mabuia nitida ).

Mabuya sloanii —Barbour, 1930:105 (part).

Mabuya sloanii — Grant, 1931:217 (part).

Mabuya sloanii — Grant, 1932a:162 (part).

Mabuya sloanii — Grant, 1932b:39 (part).

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

Mabuya mabouya sloani — Rivero, 1978:71 (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 mabouya sloani — Rivero, 1998:394 (part).

Mabuya sloanii — Mayer & Lazell, 2000:883 (part).

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

Material examined (n = 16). Puerto Rico. MCZ R-6050 (lectotype), Samuel Garman, San Juan , Puerto Rico, April 1879 ; MCZ R-176078–79 (paralectotypes), A. Stahl, San Juan, 5 February 1880 ; AMNH R-6462, R. W. Miner, Ensenada, June 1915 ; AMNH R-14007, B. A. Wall, Bayamón, 5 October 1919 ; CAS 54952, K. P. Schmidt, Ensenada, 22 September 1919 ; RT 4215, Richard Thomas, North Descalabrado , 4 February 1967 ; RT 8594, Jorge Moreno and Richard Thomas, Cerro del Muerto , 2 August 1980 ; UMMZ 73828 , Chapman Grant, vicinity of Bayamón, 5 April 1931 ; UMMZ 73829 , Chapman Grant, Cape San Juan, 2 August 1931 ; UPRRP 5401 , Julio Garcia Díaz, Barrio Coto, Isabela, 11 June 1966 . Cayo Luis Peña. UMMZ 73827 , Chapman Grant, 20 April 1931 . Cayo Norte. UPRRP 5055 , Cayo Norte, 13 April 1965 (no collector information available) . Culebra. UMMZ 239581 , C. Grant, no specific locality, April 1932 . Icacos. MCZ R-36624, Chapman Grant, 6 March 1932 ; UPRRP 2702 , Frank Torres, 9 April 1963 .

Diagnosis. Spondylurus nitidus is characterized by (1) maximum SVL in males, 87.1 mm; (2) maximum SVL in females, 95.5; (3) snout width, 2.38–3.57% SVL; (4) head length, 16.6–20.7% SVL; (5) head width, 12.5–14.6% eye, five (27%), six (73%); (13) nuchal rows, one (7%), two (80%), three (13%); (14) dorsals, 55–63; (15) ventrals, 60–66; (16) dorsals + ventrals, 117–129; (17) midbody scale rows, 28–33; (18) finger-IV lamellae, 12–15; (19) toe- IV lamellae, 14–19; (20) finger-IV + toe-IV lamellae, 26–33; (21) supranasal contact, Y (53%), N (47%); (22) prefrontal contact, N; (23) supraocular-1/frontal contact, Y (7%), N (93%); (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. nitidus 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 lower dark dorsolateral stripe width/middorsal stripe width ratio (0.292 –0.619 versus 0.64–3.79 in those other species). It is distinguished from S. haitiae sp. nov., S. lineolatus , and S. martinae sp. nov. by having a wider head (head width 12.5–14.6% SVL versus 9.58–12.3% SVL in those other species). From S. haitiae sp. nov., S. lineolatus , and S. turksae sp. nov., it is distinguished by having a longer head (head length 16.6–20.7% SVL versus 12.9–16.5% SVL in those other species). From S. lineolatus and S. turksae sp. nov., it is distinguished by having a longer toe-IV (toe-IV length 9.45–12.7% SVL versus 7.23–9.16% SVL in those other species). It differs from S. magnacruzae sp. nov. and S. spilonotus by having a lower number of midbody scale rows (28–33 versus 34 in those other species). From S. caicosae sp. nov., it is distinguished by having dark lateral stripes continuous to the hindlimbs (versus dark lateral stripes that are discontinuous or absent at the hindlimbs in S. caicosae sp. nov.). It is separated from S. haitiae sp. nov. by having a larger ear (ear length 1.32–2.36% SVL versus 1.19% in S. haitiae sp. nov.). It differs from S. macleani by having a darker middorsal stripe (versus middorsal stripe similar in color to pale dorsolateral stripes in S. macleani ). It is distinguished from S. martinae sp. nov. by having a lower number of ventrals (60–66 versus 68–71 in S. martinae sp. nov.). It is separated from S. monitae sp. nov. by having parallel dark dorsolateral stripes on the parietal scales, versus concave stripes that form a constriction on the top of the head in S. monitae sp. nov. ( Fig. 73 ).

Spondylurus nitidus also differs from other species in slightly overlapping characters. It differs from S. monae sp. nov. by having a longer toe (toe-IV length 10.1–12.7% SVL versus 8.09–10.0% SVL in 86% of specimens of S. monae sp. nov.). From S. caicosae sp. nov., it differs by having a higher number of finger-IV lamellae (13–15 in 80% of specimens versus 9–12 in 89% of specimens belonging to S. caicosae sp. nov.). From S. fulgidus , it is separated by having a lower number of supraciliaries (four in 93% of specimens versus five in S. fulgidus ) and by having a higher number of dorsals (57–63 in 80% of S. nitidus versus 52–56 in 88% of S. fulgidus ). It is distinguished from S. monitae sp. nov. by having a lower frequency of supraocular-1/frontal contact (no contact in 93% of specimens versus contact in 86% of specimens belonging to S. monitae sp. nov.). It differs from S. powelli sp. nov. by having a lower number of dorsals (55–61 in 93% of specimens versus 62–65 in 87% of specimens belonging to S. powelli sp. nov.) and by having a higher number of finger-IV + toe-IV lamellae (29–33 in 80% of specimens versus 25–28 in 81% of specimens belonging to S. powelli sp. nov.). Additionally, S. nitidus is a larger species than S. anegadae sp. nov., S. caicosae sp. nov., S. fulgidus , S. haitiae sp. nov., S. lineolatus , S. macleani , S. martinae sp. nov., S. monae sp. nov., S. monitae sp. nov., S. powelli sp. nov., S. semitaeniatus , S. sloanii , and S. turksae sp. nov. (maximum adult SVL 95.5 mm versus 63.7–94.5 in those other species). In coloration, individuals from Puerto Rico (= S. nitidus ) have been described as being "considerably darker" than those from Mona (= S. monae sp. nov.) ( Rivero 1998).

Description of lectotype ( Figs . 70D, 75A–C ). An adult female in moderate state of preservation, without injuries and with an abdominal slit. SVL 84.5 mm; tail complete (length not measured); HL 15.3 mm; HW 11.2 mm; SW 2.87 mm; EL 1.89 mm; and toe-IV length 9.32 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 in median contact, contacting anteriormost loreal. Frontonasal hexagonal, semi-diamond-shaped, wider than long, laterally in contact with anterior loreal scale. A pair of quadrilateral prefrontals, barely separated medially, and in contact with frontonasal, both anterior and posterior loreals, first supraciliary, first supraoculars, and frontal. Frontal tetragonal, lanceolate, in contact with the first supraoculars and paired frontoparietals. Frontoparietals also in contact with parietals and interparietal. Interparietal triangular, separated from nuchals by parietals; parietal eye distinct. Parietals in contact with upper secondary and tertiary temporal scales. Three and posterior loreals squarish with posteromedial projection on latter on the right; anterior and posterior loreals rectangular with posterodorsal projection on latter on the left. Two upper preoculars and two lower preoculars. Eight supralabials, the sixth 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. Eight infralabials. Mental scale wider than long, posterior margin curved slightly toward tip of snout. Postmental scale and two pairs of adjoining chin shields in contact with anterior infralabials. First and second 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, 55 in a longitudinal row; ventrals similar to dorsals; 63 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. 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. Preanal scales similar to ventrals. No enlarged median subcaudal scales on tail.

Pattern and coloration. Dorsal ground color medium brown with small dark brown spots, distributed on body, tail, and limbs. Forelimbs with dark brown mottling. Dark dorsolateral stripes present, narrow (1.52 mm), dark brown, extending from top of head to just behind ears. Dark lateral stripes present, dark brown, extending from loreal region to last third of body. Pale middorsal stripe present, wide (4.35 mm), medium brown, extending from eye to last third of body, not bordered below by a narrow dark line. Ventral surface of body without pattern. Palmar and plantar surfaces unpigmented. No information is available on color of the holotype in life.

Variation. In coloration, the pale dorsolateral stripes of S. nitidus have been described as "iridescent bluish" ( Grant 1931). However, bluish lines were not seen in a live S. nitidus described later ( Rivero 1998). Because Grant (1931) did not specifically say that his specimens of S. nitidus were alive, it is likely they were preserved. The pale (whitish) areas in mabuyines often become greenish-blue in preservative. A narrow, dark ventrolateral stripe (or line of spots), as shown in Fig. 73B , is present in some individuals but not the holotype. Variation is presented in Tables 3–5.

Distribution. The species is distributed on Puerto Rico and its satellites of Cayo Luis Peña, Cayo Norte, Culebra, Desecheo (literature record), Icacos, and Vieques (literature record; see Remarks) ( Fig. 10A, C–D ).

Ecology and conservation. Grant (1932a) made a general comment (for the Puerto Rico area, which includes multiple species) that the favorite hiding place of mabuyine skinks was in dense clumps of Opuntia cactus. Rivero (1998) also made a general comment, perhaps applying to multiple species (as recognized here) that skinks seem "to be more partial to arid and semi-arid regions" and that most specimens have been collected at the base of coconut palms, under rocks or in rock fissures, or under clumps of cacti ( Opuntia ). Other collecting locations noted included a knot hole in a fence post, trees 1–3 m above ground, on the leaf of a terrestrial bromeliad ( Bromelia pinguin ), and inside a house. Rivero also mentions that this species, on Desecheo, emerges from retreats preferentially during cloudy days.

Even as early as 1904, Stejneger remarked about the rarity of skinks in Puerto Rico, noting "its present scarcity is probably due to the mongoose." Later, Rivero (1978) noted, "The chances of seeing this species in Puerto Rico proper are quite remote.." Intensive general herpetological survey efforts by resident herpetologists in the last halfcentury have yielded only a few specimens, which were examined here. Further evidence of the scarcity of this species is that a relatively small number of specimens could be located in museum collections (from all years), with the most recent being collected in 1980. There have been more recent observations, but confirmation (e.g., photographic) that this species still exists is needed, especially because it could be confused, in the field with both native (e.g., Diploglossus pleii ) and introduced (e.g., Gymnophthalmus underwoodi , Scincella lateralis ) species of lizards (see Remarks).

The mongoose is throughout Puerto Rico and is likely the primary reason for the rarity of this species, as surmised by Stejneger (1904), although black rats are in all habitats and elevations. These and other introduced predators do not recognize the boundaries of the so-called "protected areas" in Puerto Rico (e.g., wildlife refuges and national parks), and therefore the skinks are not actually protected.

Based on IUCN Redlist criteria ( IUCN 2011), we assess the conservation status of Spondylurus nitidus to be Critically Endangered (CR A2ae). It faces a primary threat from the introduced mongoose, which has greatly reduced its numbers. 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 the main island of Puerto Rico because of its size. Also, genetic studies are needed to confirm the taxonomic status of populations of Spondylurus on the satellite islands of Puerto Rico, here assigned to S. nitidus .

Reproduction. One female (95.5 mm SVL) contained two developing young. The date of collection for that specimen was 5 April 1931.

Etymology. Not provided in the original description. However, the species name ( nitidus ), a Latin feminine singular adjective meaning "shining" or "polished," apparently refers to the coloration, described by Garman (1887) as "bronzed."

Remarks. The earliest reference to mabuyine skinks on the main island of Puerto Rico appears to have been by Cope (1862a). Skinks were recorded by Riise from Vieques ( Reinhardt & Lütken 1863), but no specimens are known to exist. It has never been seen there since then, probably because of the presence of the mongoose, and Grant (1932b) remarked that " Mabuya was not seen or known to the natives" of Vieques when he visited in 1931. It may have been one of several nearby species— S. nitidus , S. culebrae sp. nov., S. sloanii —or an undescribed species. In the first edition of his book on the amphibians and reptiles of Puerto Rico, Rivero (1978) did not list who have visited the island in recent decades have not seen it. More out of convenience, we note this old literature record ( Reinhardt & Lütken 1863) here, under S. nitidus , but suspect that it was an endemic species that probably occurred only on the island of Vieques and was wiped out by the mongoose before a specimen made it to a museum.

Two specimens of skinks collected in southwestern Puerto Rico (CAS 175490–491), on the west side of Bahía de Ballena, are not mabuyines but rather appear to be a species from the southeastern United States, Scincella lateralis . Apparently there was no mix-up of museum numbers because the collector recalls collecting those specimens (A. Bauer, personal communication). They are 39–40 mm (SVL) and have four supraoculars, seven supraciliaries, paired frontoparietals, frontonasal-frontal contact, 2–3 rows of nuchals, 60–63 dorsals, 61–72 ventrals, 26 midbody scale rows, and 14 toe-IV lamellae. In pattern they are typical of Scincella lateralis , although their dorsal counts are a bit lower than reported in the literature ( Smith 1946). Considering that nearly all of the West Indian herpetofauna is derived from South America ( Hedges 1996b), we consider it unlikely that Scincella is native to Puerto Rico, especially since that locality has been visited by many herpetologists during the last century without turning up other specimens. The best explanation is that they were introduced, probably as released pets, at a popular beach on the island.

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 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 75. Spondylurus nitidus, from Puerto Rico. (A–C) MCZ R-6050, lectotype, San Juan. (D) AMNH R-6462, Ensenada.