Varzea, 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 : 215

Genus Varzea gen. nov.

Amazonian Floodplain Skinks

Type species. Mabuya bistriata Spix, 1825:23 .

Diagnosis. Species in this genus are characterized by (1) frontoparietals, two, (2) supraciliaries, 4–5, (3) supraoculars, four, (4) prefrontal contact, absent or (less commonly) present, (5) parietal contact, present, (6) rows of nuchals, one, (7) dorsals + ventrals, 116–126, (8) total lamellae, 208, (9) a dark middorsal stripe, absent, (10) dark dorsolateral stripes, absent (except, occasionally, as rows of broken spots), (11) dark lateral stripes, present, and (12) dark ventral striping, absent. They reach 97 mm SVL ( Table 2).

Species of Varzea are not especially distinctive among mabuyines, having the normal dark lateral stripes and most of the basic head scale conditions shared with other genera. Varzea differs from Aspronema , Brasiliscincus , Capitellum , Manciola , and Psychosaura in having more total digital lamellae (208 versus 147–201). The presence of a single nuchal row separates this genus from Exila and Panopa (2–5 nuchal rows) and from most Spondylurus (usually 2–3 rows, rarely one). The presence of two frontoparietals (unfused) separates this genus from Exila , Notomabuya , and Panopa (one frontoparietal). The absence of a middorsal dark stripe further distinguishes this genus from Aspronema and Manciola . Contact of the parietal scales distinguishes this genus from the Genus Copeoglossum (parietals rarely in contact). In having four supraoculars, Varzea is separated from two genera with three supraoculars: Aspronema (rarely four) and Mabuya (rarely two or four). From Manciola (136–141 dorsals + ventrals) and Maracaiba (127 dorsals + ventrals), it differs by having fewer dorsals + ventrals (116–126). The presence of dark dorsolateral stripes, albeit narrow, short, and sometimes absent in V. altamazonica , separates Varzea from Alinea , Capitellum , Copeoglossum , Exila , Mabuya (rarely present), Maracaiba , Marisora (rarely present), and Notomabuya . Varzea differs from Psychosaura in having a typical mabuyine head shape (subacuminate) versus a prominent, acuminate head shape in Psychosaura .

Content. Two species are placed in this genus: Varzea altamazonica and V. bistriata ( Table 1).

Distribution. This genus is distributed throughout the Amazonian basin of South America, including Bolivia, Brazil, French Guiana, and Peru, and likely to occur in Ecuador ( Fig. 8B ; Miralles 2006b; Harvey et al. 2008).

Etymology. The generic name ( Varzea ) is a feminine noun, from the Portugese várzea (a pre-Roman word, Iberian in origin) meaning "flooded river bank," in allusion to the apparent preferred habitat of these species.

Remarks. The two included species in this genus cluster as closest relatives in the current molecular phylogeny ( Fig. 5 ) and in past phylogenetic analyses ( Whiting et al. 2006, with sequences labeled differently; Miralles & Carranza 2010). However, nodal support has never been significant, probably because they diverged shortly after their shared lineage split from other clades of mabuyines. Nonetheless, the two species occur in similar floodplain ( Varzea ) habitats ( Avila-Pires 1995) and replace each other geographically, with Varzea altamazonica being the upland, western species and V. bistriata being the more lowland, eastern species. Miralles and Carranza (2011) considered them to be closest relatives and referred to them as the "Riparian" Clade.

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.