Octostruma montanis Longino

Longino, John T, 2013, A revision of the ant genus Octostruma Forel 1912 (Hymenoptera, Formicidae), Zootaxa 3699, pp. 1-61 : 43-44

Octostruma montanis Longino , sp. nov.

(Figs 1C, 3B, 5P, 32, 43)

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

Geographic range. Southern Nicaragua, Costa Rica.

Diagnosis. Face lacking transverse arcuate carina; basal five teeth of mandible acute; apex of labrum bilobed; face typically with 6 spatulate setae (8 in O. 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 ).

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

The queen is unknown.

Biology. Octostruma montanis is a cloud forest species known from two sites: Cerro Musûn in southern Nicaragua and Monteverde in Costa Rica. Cerro Musûn 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 Tilaran, 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.

Comments. Three worker series from Reserva Musûn in Nicaragua are uniform in face setal pattern, as in Fig. 5P. 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 Musûn 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 O. planities , which occurs in the nearby dry-forest lowlands. In all other characters the specimens are like other O. montanis specimens.

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