Megalomyrmex nocarina Longino

Longino, John T., 2010, A taxonomic review of the ant genus Megalomyrmex Forel (Hymenoptera: Formicidae) in Central America, Zootaxa 2720, pp. 35-58 : 51-53

Megalomyrmex nocarina Longino , new species

( Figs 5 A, 5C, 10A, 10B)

Type material. Holotype worker. COSTA RICA, Heredia: Estación Biológica La Selva, 10°26'N 83°59'W, 40–125 m, 16 Sep 2005 (Proyecto TEAM AMI–1–W–044–03) [ MCZ, unique specimen identifier INB 0003678142]. Paratypes: Same data as holotype, except 4 Sep 2007 (Proyecto TEAM AMI–1–W–091–04), 1 worker [ CAS, INB 0003695485]; 12 Jun 2006 (Proyecto TEAM AMI–1–W–080–04), 1 worker [ INBC, INB 0003694200]; 7 km SW Pto. Viejo, 10°24'14"N, 084°02'22"W, 160 m, 20 Jan 2006 (Proyecto TEAM AMI–2–W–059–03), 1 worker [ LACM, INB 0003680680]; same except 24 Oct 2006 (Proyecto TEAM AMI–2–W–105–06), 1 worker [ USNM, INB 0003697094]; same except 23 Apr 2007 (Proyecto TEAM AMI–2–W–131–10), 2 workers [ UCD, CASENT 0613301; INBC, INB 0003699639]; 16 km SSW Pto. Viejo, 10°19'03"N, 084°02'56"W, 500 m, 16 Oct 2006 (Proyecto TEAM AMI–3–W–100–09), 1 worker [ MCZ, INB 0003696577]; Cantarrana, 11 km ESE La Virgen, 10°20'43"N, 084°03'28"W, 300 m, 26 Feb 2007 (Proyecto TEAM AMI–4–W–123–09), 5 workers [ CAS, CASENT 0613296; LACM, CASENT 0613297; MCZ, CASENT 0613298; USNM, CASENT 0613299; MZSP, CASENT 0613300; INBC, INB 0003646495].

Geographic range. Costa Rica.

Diagnosis. Worker differing from M. mondabora and M. mondaboroides as follows: (1) foraminal carina absent dorsally; (2) anterior clypeal margin more strongly produced and subangular, not evenly rounded.

Description. Worker. Measurements (holotype): HW 0.701, HL 0.830, SL 0.822, EL 0.234, ML 1.217, CI 84, SI 99.

Measurements (n=9): HW 0.662–0.706, HL 0.799–0.859, SL 0.786–0.876, EL 0.222–0.259, ML 1.159–1.253, CI 82–85, SI 98–102.

Palp formula 3,2; mandible with large apical and subapical teeth, 7–9 smaller basal teeth of uniform size and spacing; dorsal surface of mandible smooth and shiny; clypeus convex, bulging medially but not obscuring anterior clypeal margin in full-face view; anterior clypeal margin projecting and somewhat angular; occipital carina forming a distinct rim visible in full-face view, anterior ends extending a short distance onto ventral surface of head, not much beyond level of foramen; face, clypeus, and ventral surface of head smooth and shiny, piligerous puncta very small, resulting in overall smooth and highly polished appearance; mesosoma smooth and shiny throughout, with a few short, coarse carinae on posterior margin of katepisternum, a few longitudinal carinae over metapleural gland; foraminal carina absent, dorsal metapleural lobe curves slightly onto posterior face of propodeum but ends abruptly; petiole and postpetiole smooth and shining; ventral margin of petiole flat, with a low transverse flange anteriorly that forms a blunt tooth in lateral view, a few faint transverse costulae variably present immediately posterior to anterventral tooth; ventral margin of postpetiole with a thin transverse costa anteriorly, a shallowly convex lobe, and 2–3 transverse costulae posteriorly; gaster smooth and shining; all dorsal body surfaces and appendages with abundant flexuous setae; color dark red brown.

Queen and male unknown.

Biology. Megalomyrmex nocarina occurs in mature wet forest habitats of the Atlantic slope of Costa Rica. It occurs from near sea level to 1110 m elevation. It is known exclusively as isolated workers in Winkler samples of forest floor litter.

Etymology. The name of this species refers to the lack of a foraminal carina. It is a noun in apposition and invariant.

Comments. This species is very easy to confuse with mondabora and mondaboroides , but the lack of a strong foraminal carina is reliably diagnostic. Also, the basal mandibular teeth are slightly larger and fewer in number. The nesting and feeding habits of nocarina remain to be discovered, but the similarity to mondabora and mondaboroides suggest that nocarina , too, might be a specialized predator or social parasite of Attini .

Additional material examined. COSTA RICA: Alajuela: Casa Eladio, Rio Penas Blancas, 10°19'N, 084°43'W, 800 m, primary wet forest, 26 Apr 1987 (J. Longino); Laguna, Penas Blancas Valley, 10°20'N, 084°43'W, 1000 m, wet forest, 29 Apr 1988 (J. Longino); Guanacaste: Estacion Pitilla, Guanacaste Cons. Area, 10°59'N, 085°26'W, 700 m, 24 Jan 1991 (J. Longino); Heredia: 16 km N Vol. Barba, 10°16'N, 084°05'W, 1020 m, 9 Jul 1986 (J. Longino).

Figures

FIGURE 5. Foraminal carina (viewing posterior face of propodeum) of (A) nocarina and (B) mondaboroides. The foraminal carina is a distinct, elevated rim around the foramen in the posterior face of the propodeum, above the insertion of the petiole. It varies in completeness and may be absent dorsally, as in nocarina. Anterior clypeal margin of (C) nocarina and (D) mondaboroides.