Nesomyrmex vargasi, John T. LONGINO, 2006

John T. LONGINO, 2006, New species and nomenclatural changes for the Costa Rican ant fauna (Hymenoptera: Formicidae), Myrmecologische Nachrichten 8, pp. 131-143 : 136-137

Nesomyrmex vargasi sp.n. ( Figs. 11 - 12)

Holotype worker: Costa Rica: Heredia Prov., 15 km SSE La Virgen (10° 17' N, 84° 05' W), 1000 m elevation, 12.VII. 1986, leg. J. Longino #1365, specimen code INBIOCRI0 02281227 ( INBC).

Paratypes: 1 worker and 1 dealate queen on same pin, same data as holotype, specimen (pin) code INBIOCRI002 281 2 28 ( JTLC); 5 workers, same data as holotype but 9. VII. 1986, leg. J. Longino #1380-s, JTLC 000008515 ( LACM), JTLC 00000 8516 ( MCZC), JTLC 000008517 ( UCDC), JT LC000008518 ( CASC), JTLC 000008519 ( NMW); 1 worker, Costa Rica: Heredia Prov., 16 km SSE La Virgen (10°16' N 84°05' W), 1100 m elevation, leg. R. Vargas C. 11/RG/RVC/009, INB 0003225385 ( INBC); 1 worker, same data but 15 - 17.XI.2000, leg. J. Longino #4365-s, INBIOCR I0022 82019 ( USNM); 1 worker same data but 11.II.2001, leg. J. Longino #4385-s, LACM ENT 144699 ( BMNH).

Diagnosis of worker: Antenna 11-segmented; eye with about 11 ommatidia across greatest diameter; mandible smooth and shiny to weakly striate; all surfaces of body shiny; generally smooth and polished except for about 5 longitudinal rugae between eye and antennal insertion, about 6 longitudinal rugae on promesonotum, a few longitudinal rugulae on dorsal face of propodeum, about 3 longitudinal rugae on ventral half of side of pronotum, irregular rugulae on katepisternum and side of propodeum, about 4 longitudinal rugae on side and dorsum of petiole; side and dorsum of pronotum flat, meeting at carinate right angle; propodeal spiracles large, horizontal, opening dorsally; inferior propodeal lobes large, produced as an acute but rounded angle; anteroventral margin of petiole with acute, ventrally-directed tooth; scapes with abundant erect setae, these shorter than maximum width of scape, and with abundant underlying suberect pubescence; face with abundant short erect setae, these about as long as setae on scapes; in full face view abundant short suberect setae projecting from sides of head and margin of vertex; mesosomal and petiolar dorsa with abundant flexuous setae, these longer than those on face, longest about as long as propodeal spines; postpetiole, gastral dorsum, femora, and tibiae with abundant erect setae, these about as long as those on scapes and face; color red brown.

Measurements of holotype: HL 0.764, HW 0.722, SL 0.603, MeL 0.938.

Comments: This species keys to N. pleuriticus in KEMPF (1959). The two species have a parapatric distribution on the Barva Transect in Braulio Carrillo National Park, N. pleuriticus occurring at La Selva Biological Station and the 500 m site, N. vargasi occurring around the 1100 m site. Nesomyrmex vargasi differs from N. pleuriticus in the much smoother and shinier surface sculpture.

Etymology: Named for Ronald Vargas C., ALAS Parataxonomist from 1992 to 2005.

Range: Costa Rica.

Biology: This species occurs in mid-elevation wet forest habitats. So far it is known only from the Volcan Barva transect in Braulio Carrillo National Park, from 1000 - 1100 m elevation. I collected a nest in a treefall gap, in the 1.25 cm diameter live stem of a melastome vine. It contained 32 workers, 1 dealate queen, and abundant brood of various sizes. One specimen was collected in a Project ALAS sweep sample. Workers have been collected as foragers on low vegetation.