Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Range
Costa Rica (north slope Volcan Barba at 1000m, Penas Blancas Valley east of Monteverde, Monteverde at 1500m on Pacific slope, Volcan Cacao in Guanacaste Conservation Area).
Identification
Color red black; sides of head above eyes moderately angular; face with distinct median sulcus, punctate with smooth interspaces; scapes with differentiated, longer setae on leading edge; anterior lobe of scape moderately developed (SLL/SL 0.14); face with 16-18 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 4-6 on the posterior vertex margin, medial 4 larger and distinct, outer 2 barely discernable; specialized hairs of face spatulate, small, weakly differentiated from ground pilosity; ground pilosity dispersed on face except for medial strip, suberect; promesonotal dorsum evenly arched, propodeal suture distinctly impressed, propodeal dorsum subhorizontal, not forming a continuous curve with promesonotum; promesonotum with one pair of specialized spatulate setae on humeri; propodeal spines well developed, subtriangular; first gastral tergite with at least a few specialized erect setae, often a row of 4 at posterior margin and a pair at mid-disk, occasionally a pair anteriorly; HW 0.70, HL 0.67, SL 0.38, SLL 0.05, WL 0.75 (n=1).
Similar species: schmidti, JTL-001, JTL-008, JTL-009.
Natural History
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 from Winkler samples from scattered mid-montane wet forest sites on the central cordilleras, from Braulio Carrillo northward.
Literature Cited
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.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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