Octostruma megabalzani Longino

Longino, John T, 2013, A revision of the ant genus Octostruma Forel 1912 (Hymenoptera, Formicidae), Zootaxa 3699, pp. 1-61 : 42-43

Octostruma megabalzani Longino , sp. nov.

(Figs 1E, 3D, 5B, 9B, 31, 42)

Type material. Holotype worker: PANAMA, Chiriqui: 24 km W El Hato del Volcan [8.833, -82.754, ± 10 km], 1160 m, 26 Jun 1976, cloud forest, ex sifted leaf litter (A. F. Newton) [MCZC, unique specimen identifier MCZ-ENT 00511006]. Paratype queen, worker: same data [MCZC, MCZ-ENT00511004; USNM, MCZ-ENT00511005]. Geographic range. Bolivia, Peru, western Panama, southern Costa Rica.

Diagnosis. Differing from O. balzani as follows ( O. balzani characters in parentheses): petiole with a pair of erect setae (typically lacking); postpetiole with 2-4 erect setae (0-2); first gastral tergite with 16-22 erect setae, more or less evenly distributed on tergite, gastral setae stiff, flattened, but nearly linear, very weakly clavate (first gastral tergite with 4-16 erect setae, these clustered posteriorly, relatively more broadened apically); color dark brown (red brown); HW 0.61-0.66 (HW 0.50-0.63).

Description. Worker. HW 0.61-0.66, HL 0.56-0.61, WL 0.60-0.66, CI 107-111 (n=7). Similar in most respects to O. balzani except for the characters in the diagnosis.

Queen. HW 0.67, HL 0.62, WL 0.84, CI 108 (n=1). Labrum, mandible, scape, antennal scrobe, and head sculpture similar to worker; face with 8 erect setae distributed symmetrically around lateral and posterior margins of head, a seta on low ridge in front of each compound eye, 6 setae across vertex between compound eyes; ocelli distinct; compound eye large, multifaceted, about 12 ommatidia in longest row.

Mesosoma with queen-typical alar sclerites; sculpture like workers; anepisternum and katepisternum separated by strong sulcus; posterodorsal propodeum concave; propodeal spines pronounced, in the form of flattened perpendicular plates, acute in profile; pronotum with 4 erect setae, mesoscutum with 10, axilla with 1, scutellum with 2, metanotum with 2, petiolar node with 2, postpetiole and gaster missing from single queen available for examination. Other characters similar to worker.

Biology. Octostruma megabalzani is a montane species. The lowest elevation record is 950 m in Panama, and the highest record is 2000 m in southern Peru. It has been collected most often in mature cloud forest and montane oak forest habitats, but has also been collected in litter beneath cultivated coffee. All collections are from Berlese and Winkler samples of sifted litter and rotten wood from the forest floor.

Comments. The Andean and Central American specimens of O. megabalzani appear identical. Both occur in elevational parapatry with lowland O. balzani . Whether the Andean and Central American populations are members of one montane clade or convergently evolved montane forms is an open question.