Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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SEM images of specialized setae (Figure 11 of Hoelldobler and Wilson 1986): original, reduced.
Range
Brazil (AM), Suriname (type locality), Panama, Costa Rica (lowland rainforest areas below 500m), Honduras.
Identification
Color orange red; sides of head above eyes weakly angular; face uniformly punctate; scapes with differentiated, longer setae on leading edge; anterior lobe of scape moderately developed (SLL/SL 0.21); face with 18 specialized setae, 8 forming a double arc from eye to eye, behind this a straight row of 4, and behind this a row of 6 on the posterior vertex margin; specialized setae on face pompon-like, uniform in size, erect, distinct from smaller ground pilosity; ground pilosity evenly distributed on face; promesonotal dorsum evenly arched, propodeal suture distinctly impressed, propodeal dorsum subhorizontal, not forming a continuous curve with promesonotum; promesonotum with three pairs pompon setae (rarely with posteriormost pair or posterior 2 pairs reduced or absent); propodeal spines well developed, broadly triangular; first gastral tergite with several pairs of pompon setae; HW 0.64, HL 0.62, SL 0.39, SLL 0.08, WL 0.69 (n=1).
Very similar to JTL-002; differs in propodeal suture more impressed, propodeal dorsum more horizontal and differentiated from promesonotum, sides of head more angular above eyes, size slightly larger, and color slightly darker.
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.
In Costa Rica, I know this species from (1) 2 Berlese samples from La Selva Biological Station; (2) a worker on rotten wood at La Selva; (3) a Winkler sample from wet forest at C.A.T.I.E. near Turrialba; (4) workers in a rotten log at Hitoy Cerere Biological Reserve; and (5) a Winkler sample from wet forest near the headquarters at Carara Biological Reserve.
Type data
Rhopalothrix bolaui Mayr 1870:415. Holotype (unique syntype) queen: "Surinam/M. Hamb." [NHMW].
Rhopalothrix (Rhopalothrix) amoena Mann 1922:39. Syntype worker, queen: Honduras, La Ceiba and Cecilia [USNM, MCZC]. Synonymy by Brown and Kempf (1960).
Taxonomic notes
Costa Rican material of bolaui matches Brown and Kempf's (1960) description and figure of bolaui in all respects.
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.
Mann, W. M. 1922. Ants from Honduras and Guatemala. Proc. U. S. Natl. Mus. 61:1-54.
Mayr, G. 1870. Formicidae novogranadenses. Sitzungsber. Kais. Akad. Wiss. Wien Math.-Naturwiss. Cl. Abt. I 61:370-417.
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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