Octostruma rugiferoides

The types were collected by E. O. Wilson in leaf litter of dry, rocky, tropical evergreen forest. New material collected by the LLAMA project was in scrubby wet forest of eastern Chiapas and the seasonal evergreen forests of the Tikal region in Guatemala. All specimens were from Winkler samples of sifted leaf litter from the forest floor. (Longino 2013)

Identification
Key to Octostruma workers

Distribution based on Regional Taxon Lists
Neotropical Region: Guatemala, Mexico, Mexico.

Nomenclature

 *  rugiferoides. Octostruma rugiferoides Brown & Kempf, 1960: 200, fig. 20 (w.) MEXICO.

Worker
Holotype: TL 2.0, HL 0.53, HW 0.55 (CI 104), ML 0.13, WL 0.52 mm. Closely resembles small workers of Octostruma rugifera, but the blunt lateral angles behind the eye are reduced and ventrally displaced, so as not to be visible from full-face dorsal view; mandibles also slightly shorter. The following additional differences are noted:

1. Head and promesonotum with rugulo-reticulum overlying punctulation; concave portion of head anterior to transverse arcuate carina (including clypeus) irregularly rugulose, with a fine median longitudinal carina, weakly shining, except the posterior lobe of the clypeus and the median frontal region just behind it, which are smooth and shining. Mandibles smooth and shining. Body otherwise densely granulose-punctulate and opaque, except for the weakly shining posterior half of gaster.

2. Metanotal groove nearly or quite obsolete on the dorsum, rendering the dorsal profile in side view rather even in transition from the mesonotum into the gently sloping propodeal dorsum.

3. Petiolar node seen from side more narrowly rounded over summit.

4. Erect hairs lacking on alitrunk and both nodes; 2-3 spatulate ones at tibial apices. First gastric tergite with only a single transverse row of 4 erect clavate hairs near its posterior margin, although numerous minute, curved, reclinate ground hairs are somewhat more abundant and conspicuous over this tergite than in O. rugifera.

Longino (2013) - The description of Brown and Kempf is supplemented with these new measurements: HW 0.54–0.57, HL 0.53–0.54, WL 0.52–0.55, CI 103–105 (n=3).

Queen
Longino (2013) - HW 0.59, HL 0.57, WL 0.68, CI 103 (n=1). Posterior margin of head evenly rounded; labrum, mandible, anterior clypeal margin, scape, antennal scrobe similar to worker; clypeus smooth, delimited from frons by faint clypeal suture; concave frons anterior to facial arc sublucid, very faintly rugulose; facial arc crenulate; sculpture posterior to arc irregularly rugulose, like worker; face with 10 erect setae distributed evenly on facial arc, 6 setae on posterior margin of head; ocelli distinct; compound eye multifaceted, about 6 ommatidia in longest row.

Mesosoma with queen-typical alar sclerites; pronotum mostly foveolate, with a few rugulae on humeri; mesoscutum and scutellum with faint foveolation overlain by irregular longitudinal rugae; anepisternum and katepisternum separated by strong sulcus; mesopleuron and side of propodeum foveolate; posterodorsal propodeum forming a single concave face, faintly foveolate; propodeal spines low, obtuse, laminar, continuous with an infradental lamella; on single available queen, pronotum with 2 erect setae, mesoscutum with 6, axilla with 1, scutellum with 2, postpetiole with 3, first gastral tergite with about 24.

Type Material
Holotype worker: Mexico, Veracruz: Pueblo Nuevo, near Tetzonapa, 13 Aug 1953, in leaf litter of dry, rocky, tropical evergreen forest (E. O. Wilson) ] (examined); paratype worker: same data as holotype but 7 Aug 1953.

Determination Clarification
Longino (2013) - Palacio (1997) reports Octostruma rugiferoides for Colombia, but clearly meant Octostruma rugifera, because he describes the species as occurring in Brazil and Argentina, and gives the author as (Mayr 1887).