Spondylurus magnacruzae, 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 : 170-174

publication ID	https://doi.org/ 10.11646/zootaxa.3288.1.1
persistent identifier	https://treatment.plazi.org/id/39191A7F-07A0-FF50-2DA9-EEAA7943FA3C
treatment provided by	Felipe
scientific name	Spondylurus magnacruzae
status	sp. nov.

Treatment

Spondylurus magnacruzae sp. nov.

Greater Saint Croix Skink

( Figs. 55H View FIGURE 55 , 64D View FIGURE 64 , 68)

Mabouia aenea — Günther, 1859:212 (part).

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

Mabuya sloanii — Barbour, 1914:355 (part).

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

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

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

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

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

Mabuya sp. — Grant, 1937:512 (part).

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

Mabuya mabouya sloanei — MacLean et al., 1977:35 (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 — Henderson & Powell, 2009:293 (part).

Holotype. ZMUC-R 100 , from St. Croix , U.S. Virgin Islands, collected by " Mr. Hartmann " and accessioned 30 January 1883. An old, apparently original, label attached to the specimen with handwriting that has almost completely faded says: " Eumeces agilis, St. Croix , [Mai?] 1882, 30/1.83.v.8." This suggests that the collection date was in 1882.

Paratypes (n = 9). St. Croix , U.S. Virgin Islands . BMNH 59.3.14.18–21, collected before 14 March 1859 (no specific locality or collector available) ; KU 242174, Richard Thomas (personal communication), Green Cay, 6 August 1964 ; ZMUC-R 98 , “ Mr. Eggers,” no specific locality, accessioned 7 October 1875. See Remarks. No specific locality . ANSP 9401 View Materials , metal tag (plastic tag indicates "9410"), " West Indies ," no date, collected by Dr. H. C. Chapman (probably prior to 1862 based on accession number) ; BMNH (no number or date, but probably mid–19th century), " St. Croix ?" (no additional collection information available); ZMUC-R 95 , " West Indies," accessioned 30 March 1845 (no collector information available) .

Diagnosis. Spondylurus magnacruzae sp. nov. is characterized by (1) maximum SVL in males, 92.9 mm; (2) maximum SVL in females, 107 mm; (3) snout width, 2.29–2.97% SVL; (4) head length, 15.9–18.0% SVL; (5) head width, 11.3–14.3% SVL; (6) ear length, 1.49–1.72% SVL; (7) toe-IV length, 7.01–10.4% SVL; (8) prefrontals, two; (9) supraoculars, four; (10) supraciliaries, four; (11) frontoparietals, two; (12) supralabial below the eye, five (11%), six (89%); (13) nuchal rows, one (44%), two (56%); (14) dorsals, 60–65; (15) ventrals, 59–70; (16) dorsals + ventrals, 119–134; (17) midbody scale rows, 34; (18) finger-IV lamellae, 12–14; (19) toe-IV lamellae, 16–18; (20) finger-IV + toe-IV lamellae, 28–31; (21) supranasal contact, Y (22%), N (78%); (22) prefrontal contact, N; (23) supraocular-1/frontal contact, N; (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. magnacruzae sp. nov. is distinguished from S. anegadae sp. nov., S. culebrae sp. nov., S. haitiae sp. nov., S. macleani , S. martinae 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 (0.276 – 0.375 versus 0.500– 3.79 in those other species). It differs from S. anegadae sp. nov., S. caicosae sp. nov., S. fulgidus , S. haitiae sp. nov., S. lineolatus , S. nitidus , and S. turksae sp. nov. by having a higher number of midbody scale rows (34 versus 26–33 in those other species). It is separated from S. anegadae sp. nov., S. caicosae sp. nov., S. macleani , S. powelli sp. nov., and S. semitaeniatus by having a pale lateral stripe continuous to the hindlimbs. From S. fulgidus , it differs by having a lower number of supraciliaries (four versus five in S. fulgidus ). It differs from S. lineolatus by having a larger head (head length 15.9–18.0% SVL versus 12.9–14.4% in S. lineolatus ) and four dark stripes instead of ten.

In terms of slightly overlapping (frequency) traits, it is separated from S. monae sp. nov. by having a higher number of midbody scale rows (34 versus 28–33 in 91% of specimens belonging to S. monae sp. nov.). From S. monitae sp. nov., it differs by having a higher number of supralabials (supralabial 6 below the eye in 89% of specimens of S. magnacruzae sp. nov. versus supralabial 5 below the eye in all S. monitae sp. nov.). It is distinguished from S. powelli sp. nov. by having a lower dark dorsolateral stripe width/middorsal stripe width ratio (0.276 –0.375 versus 0.389 –0.762 in 87% of specimens belonging to S. powelli sp. nov.).

Spondylurus magnacruzae sp. nov. most closely resembles S. spilonotus , which occurs (or occurred) on St. Thomas and St. John. Both species reach 107 mm SVL in the relatively small samples available, making them the largest species in the Genus Spondylurus . They also have a similar general pattern consisting of narrow dark dorsolateral stripes in the anterior portion of the body. However, S. magnacruzae sp. nov. has fewer dorsal body spots (3–37 versus 52–99), a longer supraciliary-1 scale (supraciliary-1/supraciliary-2 length ratio 0.52–0.69 versus 0.35–0.50; Fig. 69A View FIGURE 69 ), and a smaller ear (ear length 1.49–1.72% SVL versus 1.76–2.05%; Fig. 69B View FIGURE 69 ). Also the stripe pattern of S. magnacruzae sp. nov. appears distinctly bolder and with straighter edges to the stripes, compared with that of S. spilonotus , features not obviously related to age of the specimens or differences in preservation.

Description of holotype ( Figs. 64D View FIGURE 64 , 68A–D). An adult male in good state of preservation, without injury, and with an abdominal slit. SVL 79.5 mm; tail length 128 mm (complete); HL 13.9 mm; HW 10.3 mm; SW 2.36 mm; EL 1.19 mm; and toe-IV length 6.52 mm; ear-opening average in size and round; fingers and toes clawed; 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 (right side only), first and second supraoculars, and frontal. Frontal heptagonal and lanceolate, 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, the second one being the longest and largest. Four supraciliaries, the second the longest. Nostril in posterior part of the nasal. Postnasal bordered by supranasal, anterior loreal and first the eyelid. Six moderately enlarged scales behind eye comprising the postoculars; similar to temporal scales but smaller, except primary postocular similar in size to primary 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 two pairs 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, 60 in a longitudinal row; ventrals similar to dorsals; 65 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 greenish-brown with small dark brown spots distributed sparsely on limbs and on body (posterior to the dark dorsolateral stripes). Dark dorsolateral stripes present, narrow (1.31 mm), dark brown, extending from nuchal area to first third of body. Dark lateral stripes present, dark brown with paler spots increasing from the forelimbs to the hindlimbs, extending from loreal region to hindlimbs. Pale middorsal stripe present, wide (3.49 mm), greenish-brown, extending from nuchal area to first third of body. Pale dorsolateral stripes present, greenish-white, extending from behind eye to first third of body. Pale lateral stripes present, greenish-white, extending from behind ear to midbody, bordered below by a narrow dark line. Ventral surface of body without pattern. Palmar and plantar surfaces pale or slightly gray. There is no information on color in life of the holotype.

Variation. In coloration and scalation, the paratypes resembled the holotype ( Tables 4–5), although some of the consensus pattern elements were more visible ( Fig. 55H View FIGURE 55 ).

Distribution. The species is distributed on St. Croix, U.S. Virgin Islands, 230 km 2 and its satellite Green Cay ( Fig. 10G View FIGURE 10 ).

Ecology and conservation. Spondylurus magnacruzae sp. nov. is sympatric with Capitellum parvicruzae sp. nov., apparently a much smaller species (68 mm, only specimen), on St. Croix. The fact that it co-occurred with a smaller species makes sense from an ecological (especially trophic) standpoint, although we know essentially nothing about the ecology and behavior of these species. However, the small head and digits of C. parvicruzae sp. nov. suggest that it is (or was) more ground-dwelling than S. magnacruzae sp. nov., which has a head and limbs more typical in proportion for the Genus Spondylurus . Spondylurus magnacruzae sp. nov. may have climbed trees, but it does not have the attenuate body shape and long digits of the more obviously scansorial species, S. fulgidus and Alinea pergravis . Therefore, S. magnacruzae sp. nov. probably was a species that climbed on rocks, logs, and cacti, and lived under and among them, but unlikely burrowed or lived high in trees.

In his book on St. Croix, West (1794) mentioned skinks briefly as (in error) Lacerta sputator (= Sphaerodactylus sputator Sparrman ), noting only that the locals consider them to be "deadly." The four BMNH specimens were collected on St. Croix shortly before 1859 by Alfred and Edward Newton, and their notes on the collection were communicated by Günther ( Günther 1859). They mentioned that the locals called the species the "slippery-back," a name still used in the English-speaking islands of the Caribbean. They considered the species to be more abundant than Thecadactylus (Gekkonidae) but "not often observed." Two of the four specimens were collected while copulating. No other ecological data exist on this species, and the most recently obtained specimen of Spondylurus magnacruzae sp. nov. from the main island of St. Croix was accessioned in 1883. Considerable herpetological survey work in the Virgin Islands during the 20th century failed to turn up additional specimens. The species has been found only one other time, in 1964 on Green Cay, off St. Croix, by Richard Thomas for Albert Schwartz (KU 242174). There have been no other sightings of the species on that island either, despite herpetological survey work during the last 10 years (Claudia Lombard, personal communication). The presence of the introduced mongoose on St. Croix undoubtedly explains the absence of the skink on that island today. Black rats have been a problem on Green Cay, and that may explain its apparent absence there. Habitat alteration, another threat to the species, is a continuing problem on these islands and their islets.

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 large islands such as St. Croix, but may be possible on Green Cay.

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

Etymology. The Latin species name ( magnacruzae ) is a feminine genitive singular noun referring to the larger size of this species (magna, large) compared with the other species on St. Croix, Capitellum parvicruzae sp. nov., and to its distribution. The island was named "Santa Cruz" by Christopher Columbus in 1493 and later renamed Saint Croix by the French.

Remarks. Spondylurus magnacruzae sp. nov. is probably a close relative of S. spilonotus because it shares several traits, noted above, and occurs on nearby islands. By chance, all of the large Virgin Islands skinks that we examined initially were of S. magnacruzae sp. nov., from St. Croix, and we assumed that it was the long-confused and long-synonymized " spilonotus " of Wiegmann (1837) based on general resemblance to the ZMB holotype of that species, lacking specific locality. But we were surprised that it was given the name spilonotus ("spotted back") when there were few or no spots on the backs of the St. Croix material. Then, after seeing the more abundantlyspotted material from St. Thomas and St. John (ZMUC, ZMH), more closely examining the S. spilonotus holotype pattern (also spotted), and finding additional diagnostic scale differences, it was clear to us that two large species were involved. These two Virgin Island species, at 107 mm maximum SVL , more or less tie with Alinea luciae (107 mm) and Copeoglossum aurae sp. nov. (109 mm) in being the largest in the West Indies, surpassed only by C. margaritae sp. nov. (121 mm) and C. nigropunctatum (113 mm), in being the largest of 61 species in the Subfamily Mabuyinae .

That Spondylurus magnacruzae sp. nov. occurred on St. Croix is without dispute. Collection notes on the BMNH material were published ( Günther 1859), and two of the ZMUC specimens (ZMUC-R 98, ZMUC-R 100) are identified as being from St. Croix. Specimen ZMUC-R 98 was collected, during or before 1875, by Danish army captain and naturalist Henrik Franz Alexander von Eggers. He lived on St. Croix and published a flora of the island at about that time ( Eggers 1879). Eggers also collected the holotype of Capitellum parvicruzae sp. nov. (ZMUC-R 99) on St. Croix. The two species differ in many ways and belong to different genera. Maximum body size is not known in C. parvicruzae sp. nov., but the unique specimen (68 mm SVL) is an adult, and the genus appears to be characterized by small species based on body size and small number of midbody scale rows (see Remarks for Capitellum ). Two species listed as "probably from St. Croix," ZMUC-R 91–92, are typical of S. spilonotus , and we assign them to that species. They were collected by a St. Croix pharmacist, "P. E. Benzon" (= Peder Eggert Benzon; 1788–1848), during or before 1834, but Benzon is known to have collected plant material throughout the Danish West Indies. ZMUC-R 91–92, therefore, likely came from either St. Thomas or St. John, where S. spilonotus is known to occur. The holotype of S. magnacruzae sp. nov. was collected by a "Mr. Hartmann" on St. Croix, but we were unable to determine any additional information about him, other than the fact that the Hartmanns were prominent settlers and landholders in St. Croix in the 18th and 19th centuries.