Capitellum parvicruzae, 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 : 67-70

publication ID	https://doi.org/ 10.11646/zootaxa.3288.1.1
persistent identifier	https://treatment.plazi.org/id/39191A7F-074B-FFB8-2DA9-E80A7F4CFA44
treatment provided by	Felipe
scientific name	Capitellum parvicruzae
status	sp. nov.

Treatment

Capitellum parvicruzae sp. nov.

Lesser Saint Croix Skink

( Figs. 18C View FIGURE 18 , 19C View FIGURE 19 , 22 View FIGURE 22 )

Holotype. ZMUC-R 99 , an adult female from St. Croix (no specific locality), U. S. Virgin Islands, collected by " Mr. Eggers " and accessioned on 10 July 1875.

Diagnosis. Capitellum parvicruzae sp. nov. is characterized by (1) maximum SVL in males, not available; (2) maximum SVL in females, 68.1 mm (only known specimen); (3) snout width, 3.04% SVL; (4) head length, 16.3% SVL; (5) head width, 13.0% SVL; (6) ear length, 1.38% SVL; (7) toe-IV length, 10.4% SVL; (8) prefrontals, two; (9) supraoculars, four; (10) supraciliaries, six; (11) frontoparietals, two; (12) supralabial below the eye, 6–7; (13) (22) prefrontal contact, N; (23) supraocular-1/frontal contact, N; (24) parietal contact, N; (25) pale middorsal stripe, N; (26) dark dorsolateral stripe, N; (27) dark lateral stripe, Y; (28) pale lateral stripe, Y; and (29) palms and soles, dark ( Tables 3–5).

Within the Genus Capitellum , C. parvicruzae sp. nov. differs from the other two species ( C. mariagalantae sp. nov. and C. metallicum ) in having six (versus five) supraciliaries, a larger number of total digital lamellae (190 versus 167–169), separation of the parietals (versus contact), a wider snout (3.04% SVL versus 2.41–2.55% SVL), a longer head (16.3% SVL versus 15.5–15.8% SVL), and a wider head (13.0% SVL versus 11.5–12.3% SVL). Comparison of pattern differences is made difficult by the poor condition of the specimens of C. mariagalantae sp. nov. and C. metallicum (pattern information for C. mariagalantae sp. nov. is based primarily on developing fetuses and that for C. metallicum is based on the original description and figures because the lectotype has faded). Nonetheless, C. parvicruzae sp. nov. also appears to differ in pattern from the other two species in having narrow pale dorsolateral stripes present in the first third of the body, ending just beyond the forelimb insertion (versus wider pale dorsolateral stripes that extend more than two-thirds of body in C. mariagalantae sp. nov., and no pale dorsolateral stripes in C. metallicum ; Fig. 19 View FIGURE 19 ). Additionally, C. parvicruzae sp. nov. differs from C. metallicum in having a higher number of supralabial scales (supralabial six below the eye versus supralabial five below the eye in C. metallicum ), and supranasal contact (versus no contact).

Capitellum parvicruzae sp. nov. is the only member of the Genus Capitellum in the northern Caribbean, including the Bahamas and Greater Antilles. Thus it differs from all other species of skinks in that region, including the Virgin Islands, in generic-level characters. The combination of small hands and feet, a short head, six supraciliaries, a single row of nuchals, and absence of dark dorsolateral stripes will distinguish it from other skinks in the region.

Description of holotype ( Figs. 18C View FIGURE 18 , 22 View FIGURE 22 ). An adult female in moderate state of preservation, with an injury in the nuchal area and with an abdominal slit. SVL 68.1 mm; tail length 26.7 mm (broken); HL 11.1 mm; HW 8.83 mm; SW 2.07 mm; EL 0.94 mm; and toe-IV length 7.09 mm; ear-opening large 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 roughly 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 and second supraoculars, and frontal. Frontal heptagonal, in contact with the second supraoculars and paired frontoparietals. Frontoparietals also in contact with parietals and interparietal. Interparietal tetragonal and acorn-shaped, not 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. Six supraciliaries, the third the longest. Nostril in posterior part of the nasal. A small postnasal, bordered by supranasal, anterior loreal and first supralabial. Anterior and posterior loreals squarish with posterodorsal projection on latter. Two or three upper preoculars and two (right) or three (left) lower preoculars. Eight (left) or nine (right) supralabials, the sixth (left) or seventh (right) being the widest and forming the lower border of the eyelid. Six 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. Mental scale wider than long, posterior margin curved slightly away from tip of snout. Postmental scale and two pairs of adjoining chin shields in contact with anterior infralabials. First pair of chin shields in contact medially; second and third pairs separated by smaller cycloid scales.

Body and limb scalation. One paired row of nuchal scales. 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; 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, 11 under finger-IV and 15 under toe-IV, 41/42 (L/R) on hands, 54/53 (L/R) on feet, 190 total lamellae. Preanal scales similar to ventrals. No enlarged median subcaudal scales on tail.

Pattern and coloration. Dorsal ground color medium brownish-green with scattered dark brown spots. Dark extending from nuchal area to first third of body, with dark brown edges (0.55–0.86 mm), too thin and irregular to constitute dark dorsolateral stripes. Pale lateral stripes present, whitish, extending from below eye onto tail, bordered below by a narrow (ventrolateral) dark line. Ventral surface of body without pattern. Palmar and plantar surfaces medium brown. No information is available on color in life of the holotype.

Variation. No other specimens are known. Measurements and other morphological data for the holotype are presented in Tables 3–5.

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

Ecology and conservation. No information is available on the ecology of this species (see Remarks for the genus suggesting that the species were likely terrestrial and cryptozoic). Aside from this single specimen collected at least 135 years ago, there are no other specimens or observations of the species. The mongoose was introduced to St. Croix at about that time, thus probably explaining the subsequent lack of records. It co-occurred with the large species Spondylurus magnacruzae sp. nov. (107 mm, maximum SVL ) on St. Croix, but that species, too, has not been seen since the late 19th century. Forest habitats on St. Croix are limited because of occupation by humans and concomitant manipulation of the environment.

Based on IUCN Redlist criteria ( IUCN 2011), we consider the conservation status of Capitellum parvicruzae 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 predators, 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.

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

Etymology. The Latin species name ( parvicruzae ) is a feminine genitive singular noun referring to the smaller size of this species (parvus, small) compared with the other species on St. Croix, Spondylurus magnacruzae 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. This specimen was accessioned in the ZMUC collection after the publication of Reinhardt and Lütken (1863) and thus it was not mentioned in that treatment. We have not found evidence that it has been examined previously for taxonomic reviews of mabuyine skinks, or listed in another publication, which is why we show no synonymy. Unlike the 19th century ZMH material from "St. Thomas," some of which appears to have come from other locations (see Remarks under Marisora aurulae sp. nov. and Spondylurus fulgidus ), we are more confident with locality information associated with the ZMUC material (14 specimens) from St. Thomas, St. John, and St. Croix. Except for this one specimen, the species represented are all known from the Virgin Islands (based on material in other collections).

We immediately noticed that ZMUC-R 99 was a representative of the Genus Capitellum , otherwise known from two very poorly preserved specimens from Marie-Galante and Martinique, 180–190 years old. In contrast, this specimen is well-preserved, including its color pattern. Details of the pattern agreed with C. mariagalantae sp. nov. (the pattern on C. metallicum is no longer visible but was figured and described in the original description, before it had faded) to further convince us that it was a Capitellum . The closest mainland species that it might be confused with are in the Genus Brasiliscincus . However, ZMUC-R 99 lacks the middorsal striping of species in that genus and has a higher number of dorsals + ventrals and a smaller ear. Despite being allied with Capitellum , it was sufficiently different in scalation from C. mariagalantae sp. nov. and C. metallicum to warrant recognition as a separate species, endemic to St. Croix.

The holotype of Capitellum parvicruzae sp. nov. was collected in 1875, together with a specimen of Spondylurus magnacruzae sp. nov. (the other species on St. Croix), by "Mr. Eggers." This almost certainly refers to Henrik Franz Alexander von Eggers, a Danish army captain and naturalist of St. Croix who published a Flora of the island at about that time ( Eggers 1879). Unfortunately there are no other collection data associated with the holotype, and no other specimens are known. Besides having a broken tail, it has a large injury behind the head. A puncture wound on the throat, immediately below the dorsal wound, suggests that a knife was used to kill the lizard from above, with the point of the blade exiting the throat.