Rhopalothrix apertor Longino & Boudinot

Longino, John T. & Boudinot, Brendon E., 2013, New species of Central American Rhopalothrix Mayr, 1870 (Hymenoptera, Formicidae), Zootaxa 3616 (4), pp. 301-324 : 309-310

Rhopalothrix apertor Longino & Boudinot , sp. nov.

( Figs 1 F, 2B, 3A, 6, 16)

Type material. Holotype, worker: COSTA RICA, Heredia: 7 km SW Pto Viejo, 10.40389 -84.03944 ± 500 m, 160 m, 4 Mar 2005, mature wet forest, ex sifted leaf litter (TEAM#AMI-2-W-033-01) [CAS, unique specimen identifier CASENT0629589]. Paratypes (workers): same data as holotype [USNM, CASENT0629588; MCZC, INB0003667720].

Geographic range. Costa Rica.

Diagnosis. Masticatory margin of mandible dominated by a single, blunt, peg-like tooth; tooth at base of subapical tooth, instead of being the small reclinate denticle typical of other species, is a distinct recurved tooth, directed posteriorly; first gastral tergite largely devoid of setae, with one pair of squamiform setae at posterolateral margins; first gastral sternite with pronounced median keel, this keel weak to absent in other species.

Description. Worker. HW 0.54–0.74 (n=6); masticatory margin of mandible with single large blunt, in some almost capitate, tooth at about mid-length, a tiny denticle proximad, base of subapical tooth with prominent recurved acute tooth, directed posteriorly, subapical tooth shorter than width of mandible at base, about twice as long as apical tooth, only one intercalary tooth present, outer margin of mandible broadly flattened at base; labrum about as long as broad, with two long, bluntly rounded anterior lobes, sinus between them deep, length of anterolateral lobe longer than or about equal to distance from base of sinus to transverse carina at base of labrum; arcuate promesonotal groove and metanotal groove strongly impressed; propodeal tooth small, at about midlength of posterior face of propodeum, infradental lamella very narrow; first gastral tergite largely devoid of setae, with one pair of squamiform setae at posterolateral margins; first gastral sternite with pronounced median keel.

The queen and male are unknown.

Comments. Workers of this species fall into two distinct size classes. Five specimens have HW 0.54–0.58. Four of these are from La Selva Biological Station (50–150 m elevation), all from different samples, and one is from a 500 m elevation site on the Barva Transect above La Selva. A series of three specimens from one miniWinkler sample (and thus probably from the same colony) have HW 0.74, longer and relatively thinner mesotibiae, and a more robust flattened mandibular base. These are from immediately adjacent to La Selva, at 160 m elevation. There is the potential that they are two cryptic species. The holotype and paratype were chosen from the one series of larger workers.

Biology. This species occurs in lowland rainforest, from 150–500 m elevation. All specimens are from Winkler samples of sifted leaf litter. It is rare: it occurred in three of 208 Project ALAS Berlese samples, and three of over 1500 TEAM project miniWinkler samples.

Etymology. The mandible looks like a bottle opener.

Figures

FIGURE 1. Diagrammatic representation of Rhopalothrix mandibles. A. R. andersoni, R. isthmica, R. megisthmica (part), R. therion. B. R. atitlanica, R. megisthmica (part), R. triumphalis. C. R. stannardi. D. R. nubilosa, R. subspatulata. E. R. weberi. F. R. apertor.