Leptomyrmex ramorniensis, Smith & Shattuck, 2009

Smith, Derek J. & Shattuck, Steve, 2009, Six new, unusually small ants of the genus Leptomyrmex (Hymenoptera: Formicidae), Zootaxa 2142 (1), pp. 57-68 : 66-67

Leptomyrmex ramorniensis sp. n.

( Figs 16–18 , 19–21 , 24 )

Types. Holotype worker from Ramornie State Forest, Track off T-Ridge Rd , 29°43’00”S 152°33’23”E, New South Wales, 4 Feb. to 9 Apr. 1993, M.Grey & G.Cassis ( AMSA: AMSA K 170875 ); three paratype workers, same data as holotype ( AMSA: AMSA K 170876 , AMSA K 170877, AMSA K170878 ).

Diagnosis. Head relatively short (CI greater than 80, Fig. 19 ); antennae relatively short (SI less than 150, Fig. 20 ) and extending beyond the vertex of the head by less than half their length; palps short, not reaching the posterior of the head; hind tibial spurs with barbules longer than the width of the shaft.

Worker description. With head in full face view vertex of head flat, corners rounding evenly into sides of head. Sides of head weakly curved, head widest posterior to the eyes, head relatively short and wide in comparison with other species. Eyes relatively small and placed posterior to a line drawn across the midlength of the head. Antennal scapes relatively short surpassing the vertex by about half its length. Palps relatively short, extending about ¾ the length of the underside of the head, palp formula 6, 4. Anterolateral hypostoma reduced to a thin sclerite, medial hypostoma weakly notched. Mesonotum without a raised anterior region. Dorsum of propodeum short, less than 1/3 the length of the propodeal declivity. Legs short in comparison with the other species of micro- Leptomyrmex . Hind tibial spur with well developed barbules (barbules longer than the width of the shaft), basal section smooth. Petiolar scale present, ridged and with a distinct angle dorsally, in profile acutely angular, weakly inclined anteriorly, anterior and posterior faces of the scale approximately equal in length. Head, mandibles and mesosoma uniformly brown, legs and antennae lighter, gaster darker. Erect setae found only on the clypeus and gaster. Dense white adpressed pilosity of equal length on all surfaces.

Measurements. Worker (n = 12) - CI 81–91; EL 0.16–0.19; HL 0.77–0.90 HW 0.66–0.78; MTL 0.62–0.72; SI 127–143; SL 0.87–1.05; WL 1.11–1.37.

Additional material examined. New South Wales: Ramornie S.F., track off T-Ridge Rd. (Grey,M. & Cassis,G.) (AMSA, ANIC); Ramornie SF, Headwaters of Valorem Ck., track off Mt. Tindall Rd (Cassis,G. & Grey,M.) (ASMA); Ramornie SF, Mt. Tindall Rd (Cassis,G. & Grey,M.) (ASMA).

Comments. Leptomyrmex ramorniensis is known only from Ramornie State Forest, near Grafton, northeastern New South Wales. Given the extensive trapping program undertaken in this region by NEFBS ( Grey & Cassis, 1994) and the wide distribution found for the closely related L. aitchisoni , it seems likely that this single forest represents the total range of the species.

This species is morphologically distinct from all other micro- Leptomyrmex species and is in some ways the least typical Leptomyrmex species so far known. It differs in having a shorter and wider head and relatively short antennae, palps and legs.

Figures

FIGURES 13–18. Leptomyrmex pilosus sp. n. holotype worker. Fig. 13, front of head; Fig. 14, lateral view of body; Fig. 15, dorsal view of body. Leptomyrmex ramorniensis sp. n. worker. Fig. 16, front of head; Fig. 17, lateral view of body; Fig. 18, dorsal view of body.

FIGURES 19–20. Fig. 19, graph of head length versus head width. Fig. 20, graph of scape length versus head width.

FIGURES 21–22. Distribution of material examined during this study. Fig. 21, L. aitchisoni (triangle), L. burwelli (circle) and L. ramorniensis (square). Fig. 22, L. dolichoscapus (circle), L. garretti (triangle) and L. pilosus (square). Note the restricted range of most species, especially the set in Fig. 22, where all species are essentially sympatric.

FIGURES 23–24. Fig. 23, hind tibial spur of L. burwelli. Fig. 24, hind tibial spur of L. ramorniensis.