Octostruma montanis

Octostruma montanis is a cloud forest species known from two sites: Cerro Musún in southern Nicaragua and Monteverde in Costa Rica. Cerro Musún is an isolated mountain surrounded by largely deforested lowlands. The slopes from 700 m elevation to the peak at 1400 m are a protected reserve. The LLAMA project carried out Winkler sampling across the full elevational range of the reserve, and O. montanis was restricted to parts of the reserve above 1100 m. In Monteverde in the Cordillera de Tilarán, northern Costa Rica, O. montanis occurs in the ridge crest cloud forest at 1500 m elevation, but not lower. All collections are from Winkler samples of sifted litter and rotten wood from the forest floor. (Longino 2013)

Identification
Face lacking transverse arcuate carina; basal five teeth of mandible acute; apex of labrum bilobed; face typically with 6 spatulate setae (8 in Octostruma cyrtinotum), seta-bearing pits along vertex margin large; filiform setae lacking on petiole, postpetiole, first gastral sternite; anterior half of dorsal face of propodeum convex, demarcating impressed metanotal groove; mesonotum lacking spatulate setae (with a pair in O. cyrtinotum). (Longino 2013)

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Nicaragua.

Nomenclature

 *  montanis. Octostruma montanis Longino, 2013: 43, figs. 1C, 3B, 5P, 32, 43 (w.) NICARAGUA.

Three worker series from Reserva Musún in Nicaragua are uniform in face setal pattern. Two worker series, each of two workers, are known from Monteverde, Costa Rica, and they vary in setal pattern. One series is identical to the Musún specimens, with the same number and disposition of setae, and the same enlarged seta-bearing pits. The other has only the posteromedian seta pair and the pits are not enlarged. The seta pair at the lateral vertex angles and the pair near the eyes are missing and there are no differentiated pits at these sites, so their absence is probably not due to wear. This setal pattern is the same as Octostruma planities, which occurs in the nearby dry-forest lowlands. In all other characters the specimens are like other O. montanis specimens.

Worker
HW 0.73–0.78, HL 0.69–0.72, WL 0.80–0.85, CI 106–109 (n=4). Differing from Octostruma cyrtinotum in the characters of the Diagnosis (see the identification section above); otherwise similar in most respects to O. cyrtinotum.

Type Material
Holotype worker: NICARAGUA, Matagalpa: RN Cerro Musún, 12.97796, -85.23242, ±50 m, 1350 m, 1 May 2011, wet cloud forest, ex sifted leaf litter (R.S.Anderson#2011-008), unique specimen identifier CASENT0627340]. Paratype workers: same data CASC, CASENT0623873;, CASENT0627338; , CASENT0627339; , CASENT0627341]; same data except 12.97056, -85.23388, ±20 m, 1120 m, 2 May 2011 (LLAMA, Wm-D-01-1-06) , CASENT0639986; , CASENT0639988; CASC, CASENT0639990; , CASENT0639991.

Etymology
The name refers to its restriction to montane habitats. It is a dative plural noun and thus invariant.

References based on Global Ant Biodiversity Informatics

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