Brasiliscincus, 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 : 57-58

Genus Brasiliscincus gen. nov.

Brazilian Small-headed Skinks

Type species. Scincus agilis Raddi, 1823:62 .

Diagnosis. Species in this genus are characterized by (1) frontoparietals, two, (2) supraciliaries, 5–6 (usually five), (3) supraoculars, four, (4) prefrontal contact, absent, (5) parietal contact, present, (6) rows of nuchals, one, (7) dorsals + ventrals, 113–124, (8) total digital lamellae, 157–194, (9) a dark middorsal stripe, absent, (10) dark dorsolateral stripes, usually present (rows of dark dots bordering a light mid-dorsal stripe two half-scales wide), (11) a dark lateral stripe, present, and (12) dark ventral striping, absent ( Table 2). Maximum body sizes in this genus range from 88–96 mm SVL ( Vrcibradic & Rocha 2011).

Brasiliscincus differs from others in having a combination of dorsolateral dark and pale stripes, small hands and feet, short heads, and pale palms and soles. It differs from Alinea , Copeoglossum , Mabuya , Notomabuya , Psychosaura , and Varzea in having fewer total digital lamellae (<195). It differs from Manciola in having more total lamellae (> 156), fewer dorsals + ventrals (113–124 versus 136–141), and more supraciliaries (5–6 versus four). From Maracaiba , Orosaura , and Exila (dark palms and soles) it differs in having pale palms and soles. From Aspronema (rarely four) and Mabuya (rarely two or four). The presence of a single nuchal row (versus> 1) separates this genus from Exila , Panopa , and Spondylurus . The presence of contact between the parietals separates this genus from Copeoglossum . It differs from Alinea by having fewer finger-IV + toe-IV lamellae (24–27 versus 28–36), having dark lateral stripes (present as a trace in only one species of Alinea , A. berengerae ), and lacking ventral striping. It is distinguished from Marisora by its 5–6 supraciliaries (versus four in nearly all Marisora ). Brasiliscincus shares with Capitellum small hands and feet (as reflected in similarly low counts of finger-IV + toe- IV and total lamellae). Brasiliscincus differs from Capitellum in having pale (versus dark) palms and soles and fewer dorsals + ventrals (113–124 versus 125–128).

Content. Three species are placed in this genus: Brasiliscincus agilis , B. caissara , and B. heathi ( Table 1).

Distribution. This genus is distributed in eastern and southern Brazil ( Vrcibradic et al. 2006) ( Fig. 8C ).

Etymology. The generic name ( Brasiliscincus ) is a masculine noun derived from the Latin scincus (skink) and refers to the distribution of this genus of skinks, centered in Brazil (Portuguese: Brasil).

Remarks. This genus corresponds closely to group "three" defined by Rodrigues (2000), except that we exclude Manciola guaporicola and Aspronema dorsivittatum . Rodrigues (2000) noted that these species share "vertebral stripes" on the body, although we would describe the dorsal stripes of Brasiliscincus more as "dorsolateral" rather than vertebral. Vrcibradic et al. (2006) also noted the similar pattern in these three species, describing it as consisting of a dark lateral band bordered below by a vivid white stripe, and a middorsal (pale) stripe with irregular dark borders, but acknowledging that it could be referred to as a pair of irregular dark (dorsolateral) stripes. The molecular phylogeny ( Fig. 5 ) strongly supports the clustering of these three species. This group was found in that earlier study as well ( Vrcibradic et al. 2006). The paraphyletic nature of clustering in phylogenetic trees of the species of Brasiliscincus has led to speculation that they represent a single species ( Vrcibradic et al. 2006), and recent authors have treated them as such ( Miralles & Carranza 2010). It is clear that some sequences obtained in earlier studies have been misidentified (e.g., there are low levels of sequence divergence between sequences labeled as different taxa). However, levels of sequence divergence among some of the sequences ( Fig. 5 ) are greater than among morphologically distinct species of Mabuyinae recognized elsewhere in this classification. It is for this latter reason that we consider the three species to be valid (although in need of revision). Furthermore, those levels of sequence divergence suggest that there may be additional species within Brasiliscincus . One character not scored by us was body shape. The species of Brasiliscincus have a more tubular body shape than most species of skinks, which are more dorsoventrally flattened. This was noticed by Vrcibradic & Rocha (1996) in their comparison of B. agilis and sympatric Psychosaura macrorhyncha . The species of Capitellum have a similar body shape to those of Brasiliscincus , suggesting, along with other character data, a close relationship.

Figures

FIGURE 5 (continued on the next page)

FIGURE 8. Distribution of the 16 genera of Neotropical skinks, Family Mabuyidae, Subfamily Mabuyinae. (A) Genera occurring in the greater Caribbean region. (B) Genera occurring exclusively in South America. (C) Additional genera occurring in South America, including one with representatives on Caribbean islands.