Octostruma lutzi

Longino, John T, 2013, A revision of the ant genus Octostruma Forel 1912 (Hymenoptera, Formicidae), Zootaxa 3699, pp. 1-61 : 41

Octostruma lutzi (Wheeler, 1913) Revised Status

(Figs 1E, 3D, 5A, 5B, 30, 42)

Rhopalothrix (Octostruma) lutzi Wheeler , 1913: 241. Lectotype worker: Dominica, Laudet & Long Ditton, near Roseau (Lutz) [MCZC, MCZ-ENT00303378] (examined); non-type queen: same data as lectotype [AMNH?] (not examined). Combination in Octostruma : Brown, 1949: 92. Junior synonym of Octostruma balzani : Brown & Kempf, 1960: 194. Revised Status.

Geographic range. Dominica, Guadeloupe.

Description. Worker. Dominica: HW 0.56-0.61, HL 0.55-0.59, WL 0.61-0.64, CI 102-104 (n=3). Guadeloupe: HW 0.57-0.62, HL 0.53-0.58, WL 0.60-0.65, CI 107-109 (n=6). Face setation as in Fig. 5A or 5B; mesosoma typically with two pairs spatulate setae, one on pronotum and one on mesonotum (pronotal setae lacking in all other balzani-group species except O. batesi and O. betschi ); posterolateral margin of head subequal to or longer than anterolateral margin (posterolateral margin shorter than anterolateral margin in O. batesi and O. betschi ); color dark brown on Guadeloupe.

Queen. The Dominica queen described by Wheeler was not examined. Guadeloupe queen: HW 0.65-0.66, HL 0.61-0.62, WL 0.77-0.80, CI 105-108 (n=3). Labrum, mandible, scape, antennal scrobe, and head sculpture similar to worker; face with 8-10 erect setae distributed symmetrically around lateral and posterior margins of head, a seta on low ridge in front of each compound eye, 4 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 10-12, axilla with 1, scutellum with 2, metanotum with 2, petiolar node with 4, postpetiolar disc with 4, first gastral tergite with about 40. Other characters similar to worker.

Biology. Octostruma lutzi is an island species endemic to Dominica and Guadeloupe in the Lesser Antilles. The syntypes were collected "sifting leaves in forest and among bananas and tree-ferns along the edge of it." (Wheeler, 1913). On Guadeloupe, it occurs from sea level to 800 m elevation, in a variety of forested habitats including wet and seasonal dry forest, mahogany plantation, and cloud forest. All Guadeloupe specimens are from Winkler samples of sifted litter and rotten wood from the forest floor. Dealate queens often occur together with workers in litter samples.

Comments. The original syntype series of O. lutzi contained both O. lutzi (one of which was designated lectotype in Brown and Kempf, 1960) and Eurhopalothrix guadeloupensis Longino 2013. Wheeler's description of O. lutzi pertains to O. lutzi for the most part, but the description of pilosity better fits the Eurhopalothrix worker. The identity of the described queen remains uncertain.

The degree to which the Dominica and Guadeloupe populations are differentiated is poorly known. Examined workers from Dominica (the MCZC type series of O. lutzi ) have distinctly narrower heads than workers from Guadeloupe (CI 102-104 vs. 107-109). The Dominica workers are light orange brown and the Guadeloupe workers are dark brown, but the former are also over 100 years old and may have faded.