Taxonomic Revision of the Ant Genus Leptomyrmex Mayr

2. (a) Head very elongate (HW 0.76–0.77 mm, CI 0.50–0.51; n=2); scape longer (SL 0.77–0.82 mm, SI 1.01–1.05) ...... puberulus Wheeler - (b) Head less elongate (HW 1.00–1.03 mm, CI 0.64–0.68; n = 2); scape shorter (SL 0.64–0.70 mm, SI 0.63–0.70) ...... flavitarsis F. Smith 3. (a) Body predominantly orange-brown to yellowish-brown, with variable infuscation of the gaster and mesosoma [Fig. 24e]...... fragilis F. Smith - (b) Body predominantly dark brown to black [Fig. 24f]...... melanoticus Wheeler and niger Emery

Species accounts

Accounts of the 21 species of macro-Leptomyrmex are given below in alphabetical order. See Smith & Shat- tuck (2009) for discussion of six recently described micro-Leptomyrmex species. The separate and cursory treatment of the latter is due to the very recent description of these taxa, and the fact that we have not had the opportunity to thoroughly review type material. Previous revisions of Leptomyrmex assigned the macro-species to species-groups (Wheeler, 1934), none of which are recognized here. Molecular phylogenetic analyses based on multiple nuclear markers reveal four well-supported clades within the genus, which we find to also be well-supported based on morphological evaluation (Fig. 43; Lucky, in press). Species relationships in these clades differ significantly from Wheeler’s previous species-group hypotheses. Three of the clades correspond to geographical regions of Australia’s east coast: a northern clade (L. darlingtoni, L. unicolor, L. varians, L. mjobergi plus all five New Guinea species), a central clade (L. rothneyi, L. ruficeps, L. rufipes, L. rufithorax plus all three New Caledonia species), and a southern clade (L. cnemidatus, L. erythrocephalus, L. nigriventris, L. tibialis and L. wiburdi). The fourth clade is comprised of the six micro-Leptomyrmex species known from Australia, and is strongly supported as the sister-group of the macro-Leptomyrmex species (Ward et al., 2010). Geographic distributions of the macro-Leptomyrmex species in Australia, New Guinea and New Caledo- nia are presented in figures 44–45.

FIGURE 43. Simplified cladogram depicting relationships within the genus Leptomyrmex. Triangles represent species complexes not fully resolved by molecular phylogenetic analyses; AU = Australia, NC = New Caledonia, NG = New Guinea (modified from Lucky, in press).