Lordomyrma sukuna, Sarnat, E. M., 2006

Sarnat, E. M., 2006, Lordomyrma (Hymenoptera: Formicidae) of the Fiji Islands., Bishop Museum Occasional Papers 90, pp. 9-42 : 29-32

Lordomyrma sukuna Sarnat, sp. n.

(Figs. 16, 17)

Description. Worker. TL 3.48-4.14, HL 0.78-0.91, HW 0.65-0.75, CI 0.81-0.85, SI 0.78- 0.87, REL 0.20-0.25, PSLI 0.76-1.02, MFLI 1.02-1.13, DPWI 0.81-0.95 (19 measured). A medium-sized black species with long hair, a slender petiole, short propodeal spines and reduced facial sculpture. In full face view, posterior margin of head evenly convex to slightly concave medially with rounded corners. Clypeus with one pair of carinae. Frontal carinae weakly carinate, terminating just after posterior level of eye. Antennal scrobe narrow and well defined; bordered above by frontal carinae and below by thin carinae above eye; smooth and shining with a few weak carinae near antenna insertion. Eyes of moderate size. In profile promesonotum modestly sized, convex. Propodeal spines acute, straight to slightly downcurved and divergent, in profile when measured from propodeal spiracles equal or shorter than the width of procoxa. Propodeal lobes variably sized and upturned. Petiole slender and subtriangular with steep anterior and dorsal faces. Postpetiole taller than long, smaller than petiole, apex occurring anterior to midline. Mandibles smooth and shining with sparse setigerous foveolae. Middorsum of head smooth and shining with scattered setigerous foveolae; varies from several carinae to no carinae mesad of the frontal carinae. Frontal lobes with one to two pair of carinae in addition to the frontal carinae. Sculpture surrounding eye varying from smooth and shining to patches of well developed rugoreticulum. Promesonotum smooth and shining, short longitudinal rugae present posteriorly and anteriorly. In dorsal view, propodeum smooth and shining, with a distinct transverse carina proximal to the metanotal groove. Sides of mesonotum, metapleuron, and propodeum overlain by fine, closely spaced, crenulate rugae. Petiole and postpetiole finely rugoreticulate. Gaster smooth and shining. All dorsal surfaces with very long suberect to erect acuminate yellowish hairs, the longest of which are longer than the length of the eye. Head, mesosoma and gaster black; appendages lighter.

Type Material. Holotype. Worker, FIJI: Viti Levu: Mt. Naqaranibuluti 1.3 km W Emperor Gold Mine Rest House, 17°34'10"S 177°58'20"E, 1050 m, 24.vi.2005, nesting under stone (E.M. Sarnat #2143) (FNIC). Paratypes. 15 workers, same data as holotype (ANIC, CASC, BPBM, LACM, MCZC, NMNH). Holotype will be deposited in FNIC.

Other Material Examined. FIJI: Ovalau: nr. Draiba Village 17°41'S 178°49'E, 300 m, 24.vi.2003, sifted litter (A. Rakabula). Taveuni: Qacavulo Point 16°53'S 179°57'E, 300 m, 26.ix.2003, sifted litter (M. Tokotaa & A. Caginitoba). Viti Levu: Mt. Tomaniivi, 2.4 km E Navai Village, 17°37'05"S 178°00'33"E, 950 m, 24.vi.2005, ground foraging (E.M. Sarnat #2148); Navai Forestry Camp, 11.vii.1997, in log (J.K. Wetterer #73).

Discussion. Lordomyrma sukuna can be distinguished from L. striatella by the lack of sculpturing on its face and pronotum. There is considerable variation within the material described here as L. sukuna . The most morphologically distinct specimens are the type series collected from Mt. Naqaranibuluti and a series collected from nearby Mt. Tomaniivi, both of which possess a larger size and a less sculptured face than specimens from other localities. This observation is counter to the general pattern in which sculpture tends to increase with size for individuals within a population.

Additionally, the geographic distribution of the morphological differences is counter to what one might expect. Despite being taken from the same mountain range as the two aforementioned series, the specimens from the Navai Foresty Camp share greater morphological similarity with the singletons collected from the islands of Ovalau and Taveuni. Furthermore, the Navai and Ovalau specimens exhibit sparse, short transverse carinae behind their eyes and no carinae mesad of the frontal carinae, whereas the Taveuni specimen exhibits a strongly developed network of carinae behind their eyes and posteri- or in addition to the presence of carinae immediately mesad of the frontal carinae. To further confuse matters, the Ovalau and Taveuni specimens were taken at a relatively low elevation of 300 m, whereas all of the Viti Levu series were taken from the tallest mountain range in the archipelago. Although no elevation is recorded for the Navai series, it is unlikely to be taken from below 700 m, and the other two series were collected from 950 m and 1050 m.

Considering the variability in facial sculpture observed among the Navai, Ovalau and Taveuni specimens, the unreliability of size as a discriminating character and the failure of morphometric bivariate regressions assign clear separations, I have decided to treat all of the series as belonging to a single species. Further elucidation of the morphological variability and its peculiar geographic distribution will depend upon additional evidence, such as future collections and genetic analysis.

Distribution and Biology. The Viti Levu specimens from the Navai region were taken from logs and under stones while the Ovalau and Taveuni specimens were collected from sifted litter, suggesting these ants are components of the ground fauna. The type series is from a colony collection of 30 workers that was made from a nest in soil beneath a stone, identifiable by excavated earth adjacent to the entrance.