Octostruma iheringi

Longino, John T, 2013, A revision of the ant genus Octostruma Forel 1912 (Hymenoptera, Formicidae), Zootaxa 3699, pp. 1-61 : 35-36

Octostruma iheringi (Emery, 1888)

(Figs 1D, 2, 3C, 5E, 10A, 11, 14C, 26, 43)

Rhopalothrix iheringi Emery 1888: 361. Holotype queen: Brazil, Rio Grande do Sul [MCSN] (not examined). Combination in Octostruma : Brown, 1949: 92.

Rhopalothrix godmani Forel , 1899: 41, pl. 3, fig. 4. Holotype queen: Panama, Chiriqui, David (Champion) [BMNH?] (not examined). Combination in Octostruma : Brown, 1949: 92. Junior synonym of Octostruma iheringi : Brown & Kempf, 1960: 187.

Rhopalothrix simoni Emery , 1890: 67. Holotype worker: Venezuela, Caracas (Simon) [MCSN?] (not examined). Combination in Octostruma (Octostruma) : Forel, 1912: 196. Combination in Octostruma : Brown, 1949: 92. Junior synonym of Octostruma iheringi : Brown & Kempf, 1960: 187.

Rhopalothrix simoni r. spei Forel , 1912: 196. Syntype workers: Colombia, Magdalena, "Hacienda de l'Esperanza," base of Sierra Nevada de Santa Marta, in rotten wood (Forel) [MHNG] (not examined). Combination in Octostruma : Brown, 1949: 92. Junior synonym of Octostruma iheringi : Brown & Kempf, 1960: 187.

Rhopalothrix simoni var. wighti Wheeler , 1908: 161. Syntype workers: Jamaica, road to Shot-over, 2 miles west Port Antonio, about 500ft altitude, under stone (Wight) [AMNH?, MCZC] (MCZC syntypes examined). Combination in Octostruma : Brown, 1949: 92. Junior synonym of Octostruma iheringi : Brown & Kempf, 1960: 187.

Rhopalothrix simoni st. spei var. sulcata Santschi , 1936: 201; unavailable name. Worker: Panama, "Puebloviejo" (Bierig). Material referred to Octostruma iheringi : Brown & Kempf, 1960: 187.

Geographic range. Southern Mexico to southern Brazil, Jamaica.

Description. Worker. HW 0.70-0.79, HL 0.63-0.73, WL 0.75-0.84, CI 106-111 (n=11). Labrum as in Fig. 1D and 2, sides slightly concave, strap-like lateral portions converging from base to near apex, joined by thin translucent cuticle medially but leaving distinctly bilobed apex, with median notch; mandible triangular, in profile view with mandible closed, in same plane as clypeus, apex of mandible not strongly down-turned; with mandible fully open, dorsal face tilted obliquely relative to clypeus; mandible with 8 teeth (Fig. 3C), tooth 1 continuous with basal rim of dorsal surface, teeth 1-5 acute, tooth 1 smaller than tooth 2, teeth 2-5 similar in size, a minute denticle between 4 and 5, teeth 5-8 forming an apical fork, with 5 and 8 large, 6 and 7 small partially confluent denticles; dorsal surface of mandible roughened; ventral surface flat and parallel to clypeus apically, twisting basally to nearly perpendicular orientation basally, smooth and shining; interior surface concave, smooth and shining; scape flattened, with pronounced anterobasal lobe, dorsal surface faintly sculptured; clypeus with broad, shallow emargination anteriorly; clypeus shallowly punctate or punctatorugulose; face shallowly longitudinally rugulose with shiny surface, median ruga sometimes stronger than others; frontal carinae faint, nearly obsolete; antennal socket deep, dorsal rim of socket continuous with pronounced dorsal margin of antennal scrobe; antennal scrobe deep, strongly delimited dorsally, posteriorly, and ventrally with sharply defined, translucent foliaceous cuticular rim; compound eye small, circular, composed of about 5 ommatidia; distinct carina extends from ventral margin of antennal socket across floor of scrobe to compound eye; scrobe floor faintly foveolate anteroventrally, smooth and matte to feebly shining elsewhere; vertex margin anterior to occipital carina smooth (top of head, not visible in face view); occipital carina distinct, extending anteriorly on ventral surface of head to beyond level of compound eye but not reaching hypostoma; undersurface rugulose.

Promesonotum and dorsal face of propodeum form a continuous convexity in profile; promesonotal suture obsolete; promesonotum with shallow, longitudinal impression; metanotal groove obsolete to weakly impressed; propodeum with distinct dorsal and posterior faces; propodeal spines pronounced, in the form of acute translucent perpendicular plates, extending ventrally as broad foliaceous laminae; a single broad, translucent, transverse carina extends between propodeal spines, separating dorsal and posterior faces of propodeum; this carina broadens laterally and extends onto the propodeal spine, joining it at a right angle, forming an unusual roof-like structure over the posterior face of the propodeum and creating a thin-walled, concave propodeal spine that looks like a horse ear (Fig. 10A); propodeal spiracle large, located below propodeal spine and confluent with the ventral lamina, such that the translucent lamina can be seen as the back wall when looking through the spiracular orifice; all surfaces of mesosoma matte; dorsum of promesonotum irregularly rugose, dorsal and posterior faces of propodeum smooth, lateral pronotum faintly punctate; meso-metapleuron and side of propodeum confluent, smooth.

Petiole in profile with peduncle differentiated from node, node with distinct anterior face; node nearly triangular, with long sloping dorsal face and short vertical posterior face, dorsal and posterior faces separated by a distinct transverse carina; anteroventral margin with pronounced, anteriorly-directed peg-like tooth; postpetiole low, broad, crescent-shaped in dorsal view; dorsum of petiolar node rugose; dorsum of postpetiole faintly rugulose anteriorly, grading to punctate posteriorly; first gastral tergite and sternite uniformly punctate, interspaces subequal in width to puncta , smooth and shining.

Anterior labral lobe with radiating tuft of soft, thick, translucent, capitate setae of unequal length projecting from apex (Fig. 2); each larger mandibular tooth with fully appressed seta running length of tooth; anterior margin of scape with about 10 spatulate setae; clypeus and face with fine, sparse fully appressed ground pilosity; face typically with eight erect spatulate setae arranged as in Fig. 5E; setae on vertex margin arising from large, ringed puncta ; mesosomal dorsum lacking erect setae; mesotibia with conspicuous subdecumbent clavate ground pilosity, about 2 larger spatulate seta at apex; petiole with 2 erect setae (rarely absent); postpetiole lacking erect setae; first gastral tergite lacking spatulate setae, ground pilosity fully appressed, sparse (length of setae less than distance between them); first gastral sternite with abundant short clavate setae over most of surface; pair of distinctive, long, extremely fine setae extending perpendicularly from petiolar peduncle, anterior to spiracle; similar but shorter pair of setae extending from sides of postpetiole, a few similar fine setae on anterior first gastral sternite, a short clavate seta extending posteriorly from posterior margin of hind coxa.

Color orange red.

Queen. HW 0.84, HL 0.71, WL 0.99, CI 119 (n=1). Head shape as in Fig. 14C; labrum, mandible, scape, antennal scrobe, and head sculpture similar to worker; face with 8 erect setae distributed as in worker; ocelli distinct; compound eye large, multifaceted, about 12 ommatidia in longest row.

Mesosoma with queen-typical alar sclerites; pronotum irregularly rugose anteriorly, punctatorugose laterally; mesoscutum longitudinally rugose; axilla and scutellum irregularly rugose; scutellum with median impression; anepisternum and katepisternum separated by strong sulcus; anepisternum, katepisternum, and side of propodeum matte, mostly smooth with variable faint rugulae; propodeum and propodeal spines similar to worker, but dorsal face of propodeum much shorter than posterior face; pronotum with 2 erect setae, mesoscutum with about 6, axilla with 1, scutellum with 2, metanotum with 2, petiolar node with 2, postpetiolar disc with 0, first gastral tergite with 4. Other characters similar to worker.

Biology. Octostruma iheringi is a widespread lowland species. In Central America it occurs in wet to seasonally dry habitats, in both mature and second growth forest, from sea level to about 800 m elevation. Almost all collections are from Berlese and Winkler samples of sifted litter and rotten wood from the forest floor. Dealate queens occasionally occur together with workers in litter samples. An alate queen was taken in July 1997, in the lab clearing of La Selva Biological Station, Costa Rica, a lowland rainforest site.