Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Costa Rica (Penas Blancas Valley, 800-900m).
Color dark red; sides of head above eyes moderately angular; medial face with irregular confluent puncta, not impressed; scapes with differentiated, longer setae on leading edge; anterior lobe of scape moderately developed (SLL/SL 0.19); face with 18 specialized setae, 8 forming a double arc from eye to eye, behind this a straight row of 4, lacking an outer pair near the margin at the widest point of the head, and behind this a row of 6 on the posterior vertex margin; specialized hairs of face short, usually broadly spatulate, often weakly differentiated from ground pilosity; ground pilosity suberect, conspicuous, often evenly distributed on face, at most a narrow median strip bare; promesonotal dorsum evenly arched, propodeal suture distinctly impressed, propodeal dorsum subhorizontal, not forming a continuous curve with promesonotum; promesonotum usually with one pair of specialized setae on humeri, occasionally one or two unpaired setae posteriorly; humeral setae short, broadly spatulate; several pairs of spatulate setae on gaster; propodeal spines well developed, subtriangular; HW 0.69, HL 0.64, SL 0.37, SLL 0.07, WL 0.73 (n=1).
Similar species: schmidti, JTL-001, JTL-009, JTL-010.
The genus Eurhopalothrix occurs in the Neotropics and in the Indo-Australian-southwestern Pacific area (Brown and Kempf 1960). They are members of the "cryptobiotic" fauna: small, slow ants that live in rotten wood and leaf litter. They are predators, preying on small, soft-bodied arthropods (Wilson 1956, Brown and Kempf 1960, Wilson and Brown 1985).
Workers and nests are extremely difficult to see in the field, because the workers are camouflaged and very slow moving. On disturbance they freeze, often curling into a pupal position, and remain motionless for several minutes (Wilson and Brown 1985, Hoelldobler and Wilson 1986). As a result of their cryptic nature, they were considered extremely rare until the 1960's. But increasing use of Winkler and Berlese sampling has shown Eurhopalothrix to be relatively common. I encounter them in most Winkler samples from wet forest sites in Costa Rica.
This species is known only from the Penas Blancas Valley east of Monteverde, where it is relatively abundant in Winkler samples.
This species keys to gravis in Brown and Kempf (1960).
Brown, W. L., Jr., Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3:161-250.
Hoelldobler, B., Wilson, E. O. 1986. Soil-binding pilosity and camouflage in ants of the tribes Basicerotini and Stegomyrmecini (Hymenoptera, Formicidae). Zoomorphology (Berl.) 106:12-20.
Wilson, E. O. 1956. Feeding behavior in the ant Rhopalothrix biroi Szabo. Psyche (Camb.) 63:21-23.
Wilson, E. O., Brown, W. L., Jr. 1985 ("1984"). Behavior of the cryptobiotic predaceous ant Eurhopalothrix heliscata, n. sp. (Hymenoptera: Formicidae: Basicerotini). Insectes Soc. 31:408-428.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.email@example.com
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