Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Costa Rica (Atlantic lowland wet forest).
Gastral dorsum with at most one pair of spatulate setae a little over half way back, and a cluster near the apex; labrum deeply notched with lateral lobes rounded; side of head above antennal insertions with three subequal gibbosities, nearly aligned, giving the head a subquadrate aspect.
The genus Rhopalothrix is a member of the monophyletic tribe Basicerotini (Bolton 1998). I assume that Rhopalothrix share the predaceous habits of other members of the tribe. The few basicerotines whose habits are known prey on small, soft-bodied arthropods (Wilson 1956, Brown and Kempf 1960, Wilson and Brown 1985).
I know this species from three Berlese samples from La Selva Biological Station.
JTL-004 is similar to isthmica in size and in the deeply bilobed labrum. isthmica is described with the inner surface of the mandibles having 7 acute teeth alternating in two sizes. JTL-004 has a single, large, subquadrate tooth (probably two fused teeth). isthmica is described with spatulate setae on the posterior half of the gaster; on JTL-004 there are only a few clustered at the very apex. Weber's figure of the head shape of isthmica is intermediate between JTL-004 and weberi.
Acanthidris isthmicus Weber 1941:188. Holotype worker: Panama, Barro Colorado Island [Weber collection?]. Brown and Kempf also examined a USNM specimen from the same locality.
Bolton, B. 1998. Monophyly of the dacetonine tribe-group and its component tribes (Hymenoptera: Formicidae). Bulletin of the Natural History Museum London (Entomology) 67:65-78.
Brown, W. L., Jr., Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3:161-250.
Weber, N. A. 1941. Four new genera of Ethiopian and Neotropical Formicidae. Ann. Entomol. Soc. Am. 34:183-194.
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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