Capitellum metallicum ( Bocourt 1879 ) 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 : 64-67

Capitellum metallicum ( Bocourt 1879) comb. nov.

Lesser Martinique Skink

( Figs. 18B , 19B , 21 )

Mabuya metallica — Bocourt, 1879:400 (new lectotype designation: MNHN 5424 , from " Martinique," coll. Auguste Plée, ca. 1820) .

Mabuya agilis — Boulenger, 1887:190 (part).

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

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

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

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

Mabuya mabouya mabouya —Peters & Donoso-Barros, 1970:200 (part).

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

Mabuya mabouya mabouya — Schwartz & Henderson, 1988:150 (part).

Mabuya mabouya mabouya — Schwartz & Henderson, 1991:457 (part).

Mabuya bistriata — Powell et al., 1996:82 (part).

Mabuya bistriata — Malhotra & Thorpe, 1999:34 (part).

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

Mabuya mabouya — Breuil, 2002:267 (part).

Mabuya mabouya — Henderson & Powell, 2009:292 (part).

Material examined (n = 1). Martinique. MNHN 5424 (lectotype), an adult female, collected on " Martinique " by Auguste Plée in ca. 1820. The only known surviving specimen of the type series .

Other material (n = 2). Martinique. MNHN (unknown numbers), paralectotypes, one of which was figured by Bocourt (1879, Plate 22B, Fig. 1 ), both apparently lost .

Diagnosis. Capitellum metallicum is characterized by (1) maximum SVL in males, not available; (2) maximum SVL in females, 74.0 mm (only known specimen); (3) snout width, 2.41% SVL; (4) head length, 15.5% SVL; (5) head width, 11.5% SVL; (6) ear length, 1.53% SVL; (7) toe-IV length, 10.6% SVL; (8) prefrontals, two; (9) supraoculars, four; (10) supraciliaries, five; (11) frontoparietals, 2; (12) supralabial below the eye, five; (13) nuchal rows, one; (14) dorsals, 62; (15) ventrals, 66; (16) dorsals + ventrals, 128; (17) midbody scale rows, 30; (18) finger-IV lamellae, 10; (19) toe-IV lamellae, 14; (20) finger-IV + toe-IV lamellae, 24; (21) supranasal contact, N; (22) prefrontal contact, N; (23) supraocular-1/frontal contact, N; (24) parietal contact, Y; (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. metallicum differs from C. mariagalantae sp. nov. by having a lower number of supralabial scales (supralabial 5 below the eye versus supralabial 6 or 7 below the eye in C. mariagalantae sp. nov.), a longer toe (toe-IV 10.6% SVL versus 9.5% SVL in C. mariagalantae sp. nov.), and a narrower head (head width 11.5% SVL versus 12.3% SVL in C. mariagalantae sp. nov.). In pattern, C. metallicum is a less boldly stripes that extend the full length of the body and onto the tail. In scalation, C. metallicum differs from C. parvicruzae sp. nov. in having five supraciliaries (versus six), parietal contact (versus no contact), absence of supranasal contact (versus contact), and 167 (versus 190) total digital lamellae.

Capitellum metallicum also differs from species in other genera inhabiting nearby islands in the Lesser Antilles (see Tables 3–5). In form it differs from most in being small-headed and gracile, with a tubular-shaped (versus dorsoventrally flattened) body. From the species on the same island, Mabuya mabouya , C. metallicum differs by having five supraciliaries (not 3–4); four supraoculars (not three); fewer finger-IV (10 versus 13–16), toe-IV (14 versus 17–19), and combined (24 versus 30–34) lamellae; a shorter head (head length 15.5% SVL versus 16.2– 19.2% in M. mabouya ); a narrower head (head width 11.5% SVL versus 12.1–14.9% SVL in M. mabouya ); and no supraocular-1/frontal contact (present in M. mabouya ).

Description of lectotype ( Figs . 18B, 21 ). An adult female in poor state of preservation (soft), without injuries and with an abdominal slit. SVL 74.0 mm; tail length 113 mm (complete); HL 11.5 mm; HW 8.52 mm; SW 1.78 mm; EL 1.13 mm; and toe-IV length 7.85 mm; ear-opening average in size and oval; toe length in the following order: I <V <II <III <IV.

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 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 largest. Five 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. Three upper preoculars and two lower preoculars. Seven supralabials, the fifth being the widest and forming the lower border of the eyelid. Five moderately enlarged scales behind eye (three on the left) 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 fairly straight. 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 row of paired nuchal scales. Other scales on nape similar to dorsals. On lateral sides of neck, scales slightly smaller. Dorsal scales cycloid, imbricate, smooth, 62 in a longitudinal row; ventrals similar to dorsals, 66 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, 10 under finger-IV and 14 under toe-IV, 38/37 (L/R) on hands, 46/46 on feet, 167 total lamellae. Four preanals larger than adjacent ventral scales. No enlarged median subcaudal scales on tail.

Pattern and coloration. Pattern and coloration are mostly not determinable because of fading with age and the poor state of preservation of the specimen, which appears uniformly grayish-brown. The loss of pattern is likely from exposure to light during the last two centuries because the concealed areas (palms, and behind arms and legs folded against side of body) show original brown pigment, indicating that the palms and soles were dark and the limbs were finely mottled. No information is available on color in life of the lectotype.

Variation. Bocourt (1879) described three specimens (two now lost) and figured one of them (her Plate 22B, Fig. 1 ). Based on subtle details of the head scalation (e.g., narrower separation of prefrontals and different overlap of nuchals), her illustrated specimen is clearly not the lectotype but agrees with the lectotype in two diagnostic characters (four supraoculars and five supraciliaries) and in other general characters (separation of supranasals, separation of prefrontals, contact of parietals). In the text description she states that there are 26–28 midbody scale rows (we count 30 in the lectotype); supralabial 5 is below the eye; and one row of nuchals, 55–60 dorsals (we count 62 in lectotype), and four supraoculars (she notes three on one side of one specimen) are present. She also mentions four supraciliaries, but her illustration shows five, and we count five in the lectotype, so the mention of four is unexplained. Also the measurements given of a large (98 mm SVL) unsexed specimen ( Bocourt 1879) are consistent with Mabuya mabouya in size and head shape, and not with the lectotype, and therefore we have not incorporated those measurements here. In pattern, the species is noted as having "the upper region of the body tinged with sienna metallic greenish reflections." A brown lateral stripe, bordered below by a yellow stripe, is described on the head and anterior of the body, disappearing behind the forearms. The venter is described as having "metallic tones of a greenish yellow." Bocourt's figure shows two dark lateral stripes and a lack of dorsal striping, consistent with that description. Mabuya mabouya , also from Martinique, differs only slightly from that description, in having some evidence of pale dorsolateral stripes and dark dorsal flecks. Otherwise Boucourt's description (and figure) of the pattern of Capitellum metallicum is similar to that of M. mabouya .

Distribution. The species is known only from a single specimen collected at an unknown locality on Martinique ( Fig. 11C ).

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). Multiple individuals of two species of ticks are attached in concealed areas behind the left arm. The lectotype was collected nearly two centuries ago, and there are no other existing specimens. The mongoose was introduced to Martinique, and rats are present as well ,

Based on IUCN Redlist criteria ( IUCN 2011), we consider the conservation status of Capitellum metallicum 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. There are islets of Martinique that do not have mongooses and might sustain populations of this skink.

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

Etymology. The species name is a feminine adjective referring to the coppery, metallic color of the preserved specimens described by Bocourt (1879).

Remarks. Shortly after Capitellum metallicum was described, it was synonymized with Brasiliscincus agilis ( Boulenger 1887) and later with Mabuya mabouya ( Dunn 1936) , where it has remained in synonymy until now. However, this is quite surprising considering how different this species is from M. mabouya , the other species on Martinique.

Bocourt (1879) mentioned that she examined three specimens for the description of Capitellum metallicum . However, there is no record of any other specimen numbers besides MNHN 5424 ( Brygoo 1985), and therefore they appear to be lost. Fortunately she described some aspects of scalation and pattern in those three specimens and figured one of them, which was not the lectotype (see above, Variation). As noted by Bocourt (1879), at least one of the three specimens (and probably all three) was collected by Plée. Auguste Plée (1787–1825) collected in Martinique in ca. 1820 for the MNHN, and his skink material was examined by Duméril and Bibron (1839) and later by Bocourt (1879). Bocourt noted that one of the specimens of C. metallicum (the one with three supraoculars on one side) was treated by Duméril and Bibron (1839) as a variety of Eumeces mabouia (=redescription of Mabuya mabouya ). Because M. mabouya has four supraciliaries, a similar pattern, and occasionally four supraoculars, it is possible that one of Bocourt's two lost specimens was an M. mabouya , something that is impossible to confirm. The small head and small number of digital lamellae, characters that we find to be especially diagnostic, were not considered by Bocourt. We accept Bocourt's description of pattern in this species only because her figure of C. metallicum shows an animal with four supraoculars and five supraciliaries on both sides (agreeing with characters of the lectotype), and the illustrated pattern agrees with her description. Otherwise we refrain from accepting other textual information from Bocourt regarding this species because of our concerns that it may pertain to confusion with M. mabouya .

Martinique is a large island that is a composite of multiple paleoislands, and other reptiles show geographic variation within Martinique ( Breuil 2002; Hedges 2008; Thorpe et al. 2010). There is no specific locality for Capitellum metallicum , and the only specific localities for Mabuya mabouya are on the "North Island" (=northern half of Martinique). Without specific knowledge otherwise, sympatry between the two species on Martinique must be assumed, although C. metallicum may have occupied the South Island, allopatric from M. mabouya on the North Island. The size difference in the two species, and the apparent terrestrial and cryptozoic habits of C. metallicum , would have reduced competition between them in sympatry.

Figures

FIGURE 1. Map of Caribbean region. Neotropical skinks occur, or once occurred, on the islands indicated.

FIGURE 11. Map showing the distribution of mabuyine skinks occurring in the Lesser Antilles and Trinidad and Tobago. See Fig. 1 for location of the islands. The islands and species are: (A) Anguilla, Dog Island, and St. Barts (Spondylurus powelli sp. nov., squares), and St. Martin (S. martinae sp. nov., circle); (B) Guadeloupe: Basse-Terre (Mabuya guadeloupae sp. nov., square), Grande-Terre (Mabuya grandisterrae sp. nov., triangle), Îlet à Cochons (Mabuya cochonae sp. nov., star), La Désirade and Terre de Bas, Petite-Terre (Mabuya desiradae sp. nov., diamonds), and Marie-Galante (Capitellum mariagalantae sp. nov., circle); (C) Martinique (Mabuya mabouya, circles; Capitellum metallicum, triangle); (D) St. Vincent, the Grenadines, and Grenada (Copeoglossum aurae sp. nov., circles; Marisora aurulae sp. nov., triangles); (E) Redonda (Copeoglossum redondae sp. nov., circle) and Montserrat (Mabuya montserratae sp. nov., square); (F) Dominica (Mabuya dominicana); (G) St. Lucia (Alinea luciae), (H) Barbados (Alinea lanceolata); (I) Trinidad (Copeoglossum aurae sp. nov., circles; Marisora aurulae sp. nov., triangle), and (J) Tobago (Copeoglossum aurae sp. nov., circles; Marisora aurulae sp. nov., triangles). Hollow symbols in A and J are literature records (specimens not examined). Where no specific localities within an island are known for a species, a symbol is placed centrally on the island: Alinea luciae, Capitellum mariagalantae, Capitellum metallicum, and Copeoglossum redondae sp. nov. The scale in (A) applies to all islands.

FIGURE 18. Head scalation in species of the Genus Capitellum (left, side view; right, dorsal view). (A) C. mariagalantae sp. nov. (ANSP 9413, holotype); (B) C. metallicum (MNHN 5424, lectotype); and (C) C. parvicruzae sp. nov. (ZMUC-R 99, holotype).

FIGURE 19. Representative patterns in species of the Genus Capitellum (top, dorsal view; bottom, side view). (A) C. mariagalantae sp. nov.; (B) C. metallicum; and (C) C. parvicruzae sp. nov.

FIGURE 21. Capitellum metallicum, from Martinique. (A–F) MNHN 5424, lectotype, “Martinique.”