Leptotyphlops Fitzinger, 1843

Adalsteinsson, Solny A., Branch, William R., Trape, Sébastien, Vitt, Laurie J. & Hedges, S. Blair, 2009, Molecular phylogeny, classification, and biogeography of snakes of the Family Leptotyphlopidae (Reptilia, Squamata), Zootaxa 2244, pp. 1-50 : 29-33

Genus Leptotyphlops Fitzinger, 1843

Glauconia Gray, 1845: 139 . Type species: Typhlops nigricans Schlegel, 1839 , by monotypy.

Type species. Typhlops nigricans Schlegel, 1839 , by original designation.

Diagnosis. Species of Leptotyphlops have 14 midbody scale rows, 10–12 midtail scale rows, 171–322 middorsal scale rows, 18–44 subcaudals, two supralabials, a small anterior supralabial (moderate in L. howelli ), 126–292 mm maximum adult total length, a body shape of 36–106 (total length/width), a relative tail length of 5.1–13.7 %, a tail shape of 3.4–9.2, no striped pattern, and usually a dark brown or brown dorsum and venter (Table 2). Members of Leptotyphlops can be distinguished from the other genus in the Tribe Leptotyphlopini (described below) by having a heart-shaped or subtriangular (rather than semilunate) cloacal shield, a lower number (on average) of middorsal scales (171–322 versus 241–387), and a less attenuate body shape (36–106 versus 45–142). The support for this group was 100% BP and 100% PP for the four-gene tree ( Fig. 3) and 100% BP and 100% PP for the nine-gene tree ( Fig. 4).

Content. Twenty-two species ( Table 1; Fig. 9).

Distribution. Leptotyphlops is distributed throughout South Africa, extending as far north as the Democratic Republic of the Congo in the west and Somalia in the east, including Pemba Island off Tanzania and the Bazaruto archipelago off of Mozambique ( Fig. 11).

Etymology. The generic name is masculine and derived from the Greek adjective leptos (thin) and Greek noun typhlops (blind), in allusion to the attenuate body shape and reduced vision of these snakes.

Remarks. This genus comprises the former nigricans and scutifrons groups of Leptotyphlops , most recently defined by Broadley and Wallach (2007). See "Remarks" above under the Subfamily Leptotyphlopinae and Tribe Leptotyphlopini regarding diagnostic characters used in the past for these species groups, and the reason for abandoning them.

We sampled nine of the 22 described species in the genus as recognized here. Among these, three deeplybranching clades are evident: Central Africa ( Leptotyphlops kafubi ), East Africa ( L. merkeri , L. nigroterminus , and L. pitmani ), and South Africa (all other species). The geographic concordance of these phylogenetic groups suggests that other species from the three regions will join the respective groups when sampled. However, they may not, and there is not yet clear morphological support for these three clades. Thus we refrain from recognizing species groups within Leptotyphlops until additional species are sampled genetically. Leptotyphlops merkeri and L. pitmani were most recently treated as northern races of L. scutifrons ( Broadley & Wallach 2007) , whilst L. kafubi was included in the nigricans Group and L. nigroterminus in the scutifrons Group ( Broadley & Wallach 2007). None of these arrangements are supported by molecular data. The relationships between the deeply divergent L. kafubi and other East African leptotyphlopids previously synonymized or associated with South Africa L. nigricans —i.e. L. emini , L. howelli , L. pembae , L. macrops , L. monticolus , L. mbanjensis , L. keniensis , and L. aethiopicus ( Broadley & Wallach 2007) — requires further study. The species L. pungwensis was not included in the size range for total length because the single known specimen (90 mm) is a juvenile.

An additional complication is the large sequence divergence observed among samples assigned to the same species, such as L. conjunctus , L. nigricans , L. scutifrons , and L. sylvicolus ( Fig. 3). Based on levels of sequence divergence among other valid species in the phylogeny, at least 12 unrecognized species would appear to be present among samples assigned to those four species alone. The fact that one species ( L. conjunctus ) is polyphyletic ( Fig. 3) further supports the presence of cryptic species. While we accept that L. incognitus is a valid species ( Broadley & Broadley 1999), we lack genetic material from the type locality (Umtali, Zimbabwe) and are therefore unable at this time to correctly assign any of our material of L. conjunctus or L. scutifrons to this taxon. This problem requires further study utilizing additional morphological and molecular data, especially from type localities (Branch and Hedges in prep.); we suggest that each of these species be referred to as a "complex."