Marisora magnacornae, 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 : 129-131

publication ID	https://doi.org/ 10.11646/zootaxa.3288.1.1
persistent identifier	https://treatment.plazi.org/id/39191A7F-0789-FF7F-2DA9-ECB278DFF841
treatment provided by	Felipe
scientific name	Marisora magnacornae
status	sp. nov.

Treatment

Marisora magnacornae sp. nov.

Corn Island Skink

( Figs. 46B View FIGURE 46 , 47B View FIGURE 47 , 51 View FIGURE 51 )

Mabuya agilis — Barbour & Loveridge, 1929:142 (part).

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

Mabuya brachypodus — Taylor, 1956:308 (part).

Mabuya brachypoda — Webb, 1958:1311 (part).

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

Mabuya unimarginata — Villa et al., 1988:54 (part).

Mabuya brachypoda — Campbell, 1998:167 (part).

Mabuya unimarginata — Lee, 1996:247 (part).

Mabuya unimarginata —Savage, 2002:503 (part).

Holotype. MCZ R-26976, an adult male collected between 10 December 1927 and 3 January 1928 on Great Corn Island , Nicaragua by James L. Peters (Peters 1929).

Diagnosis. Marisora magnacornae sp. nov. is characterized by (1) maximum SVL in males, 77.4 mm; (2) maximum SVL in females, not available; (3) snout width, 2.71% SVL; (4) head length, 18.6% SVL; (5) head width, 14.0% SVL; (6) ear length, 1.36% SVL; (7) toe-IV length, 12.4% SVL; (8) prefrontals, two; (9) supraoculars, four; (10) supraciliaries, four; (11) frontoparietals, two; (12) supralabial below the eye, five; (13) nuchal rows, one; (14) dorsals, 57; (15) ventrals, 60; (16) dorsals + ventrals, 117; (17) midbody scale rows, 30; (18) finger-IV lamellae, 12; (19) toe-IV lamellae, 17; (20) finger-IV + toe-IV lamellae, 29; (21) supranasal contact, Y; (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, pale ( Tables 3–5).

Marisora magnacornae sp. nov. differs from all other species in the Genus Marisora in having a longer toe-IV (12.4% SVL versus 7.96–11.9% in other species except M. brachypoda ; 7.43–12.2% SVL in 89% of that species). It also differs from individual species in other characters. The limbs of M. magnacornae sp. nov. are longer than most species (arm + leg length 62.3% SVL), and in this character it differs from M. aurulae sp. nov. (53.7–55.9% SVL), M. brachypoda (45.3–61.7% SVL), M. falconensis (53.5–61.6% SVL), and M. roatanae sp. nov. (54.5– 56.2% SVL; Fig. 49 View FIGURE 49 ). Marisora magnacornae sp. nov. also differs in having fewer dorsals + ventrals (117) than M. roatanae sp. nov. (122–125). From M. alliacea it differs in having 30 midbody scale rows (versus 26–29) and in lacking dark dorsolateral stripes (present in M. alliacea ). From M. roatanae sp. nov. it additionally differs in having 30 midbody scale rows (versus 32), a relatively longer supraciliary-1 scale (1.61% SVL versus 1.04–1.29%; Fig. 50A View FIGURE 50 ), and absence of pale ventrolateral stripes. From M. unimarginata it differs in having two pairs (versus one pair) of chin shields in contact with the infralabials, a narrower pale lateral stripe (1.10% SVL versus 1.43– 1.89%) and in having the pale lateral stripe passing through the lower half of the ear opening (that stripe passes through all or most of the ear opening in M. unimarginata ).

EL 1.05 mm; and toe-IV length 9.59 mm; ear-opening average 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 on the left. Frontonasal heptagonal, wider than long, laterally in contact with anterior loreal scale on the left. On the right, a small scale is present between the frontonasal and anterior loreal. 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, 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. Four supraciliaries, the second the longest. Nostril in posterior part of the nasal. A small postnasal, bordered by supranasal, anterior loreal, and first supralabial. Anterior loreal rectangular and posterior loreal squarish with posterodorsal projection on latter. Three upper preoculars (four on the left) 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 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 straight. Postmental scale and two pairs of chin shields in contact with anterior infralabials. First pair of chin

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, 57 in a longitudinal row; ventrals similar to dorsals; 60 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, 12 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 brown with small dark brown spots, distributed uniformly and in two dorsolateral bands on body, in broken lines on tail, and uniformly on limbs. Dark dorsolateral stripes absent. Dark lateral stripes present, extending from loreal region past hindlimbs and onto base of tail. Pale middorsal stripe absent. Pale dorsolateral stripes absent. Pale lateral stripes present, pale gray, extending from behind eye past hindlimbs, bordered below by a narrow dark line. Ventral surface of body without pattern. Palmar and plantar surfaces unpigmented. 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 Great Corn Island (10 km 2), Nicaragua ( Fig. 1 View FIGURE 1 ), located approximately 50 km from the Nicaraguan coast. The precise locality on Great Corn Island where the holotype was collected is unknown, and therefore no map is shown here. It is also unknown whether it or a related species occurs on Little Corn Island (2.9 km 2).

Ecology and conservation. No information is available in the original account of the expedition except that the species is called "slitch" by the islanders ( Barbour & Loveridge 1929). The only known specimen of the species was collected nearly a century ago. Recent photographs of this small island show some forest present (apparently unprotected), as well as roads, an airport, settlements, and farm animals. It can be assumed that rats are present, and these may pose the most significant threat to this species.

Based on IUCN Redlist criteria ( IUCN 2011), we assess the conservation status of Marisora magnacornae sp. nov. as Endangered (EN A2ace). It faces a primary threat from predation by introduced mammals, including black rats, and a secondary threat from habitat alteration. 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 considered, if the species still exists.

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

Etymology. The species name ( magnacornae ) is a feminine genitive singular noun, referring to the island on which the species occurs. Although formally called Great Corn Island, it is usually called simply " Corn Island," and hence the English common name, Corn Island Skink. The language of Nicaragua is Spanish, but the Corn Islands were named by the British, and the government of Nicaragua maintains the English name as the official name for the islands. Hence we use that English name as a stem for the species name.

Remarks. Although Marisora magnacornae sp. nov. has unique scale characters that distinguish it from other species, it is not particularly distinctive in pattern, and it probably was medium brown in life with dark brown markings. Marisora magnacornae sp. nov. and M. unimarginata have the longest limbs in the genus, in contrast to geographically proximal M. brachypoda (short limbs). No specimens of M. unimarginata are yet known from adjacent Nicaragua or eastern Coast Rica. However, two specimens of Marisora brachypoda from eastern Nicaragua, USNM 19872–73, are unusual in having a mixture of characters (long limbs, two pairs of chin shields in contact with infralabials, long toe-IV (11.2–12.7% SVL), and 30 midbody scale rows) that combined distinguish them from other species. They may represent aberrant specimens of M. magnacornae sp. nov., or of other species such as M. brachypoda or M. unimarginata , or they may represent an undescribed species.

Marisora magnacornae sp. nov. may have arisen as a vicariant relict of an ancestral species (a close relative of M. unimarginata ) that was more widely distributed during Pleistocene glaciations when low sea levels exposed the continental shelf. Alternatively, it may have rafted to the island at some point in the past, presumably from points south (e.g., Panama) or east based on ocean currents in that portion of the Caribbean. The highest elevation on the island is approximately 110 m, which would have meant that some land would have been emergent during Pleistocene interglacial high stands, assuming that no geological uplift has since occurred.