Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Range
The type locality of humilis is Panama (Barro Colorado Island). I have seen humilis-like material from Venezuela, Trinidad, Panama, and Costa Rica. In Costa Rica I have seen specimens only from the Osa Peninsula region, in spite of extensive collecting elsewhere.
Identification
Antennae 7 segmented; face somewhat shiny, not mat or punctate; interantennal lamella projecting as an acute angle between antennal insertions, descending to relatively shorter clypeal shelf, so that lamella appears triangular in lateral view; lamella relatively smaller compared to sexarticulata and JTL-005, no more than a tooth originating between antennal insertions, well above anterior margin of clypeus, such that in side view lamella is usually not visible, obscured by antennal scapes; anterior clypeal apron flat and very short compared to sexarticulata and JTL-005.
Natural History
Discothyrea are extremely small, cryptobiotic inhabitatants of forest leaf litter (see Genus Overview). In Costa Rica, I have collected workers of this species from three different Winkler samples from three different sites on and near the Osa Peninsula: Sirena, Rancho Quemado, and a site 19km S of Ciudad Neilly.
Notes
There is a complex of species around humilis. In Costa Rica there are three species: humilis, sexarticulata, and JTL-005. In P. S. Ward's collection at UC Davis I observed specimens from Colombia and Venezuela that matched Costa Rican and Panamanian humilis, although they were quite variable in size. There was also material from the Dominican Republic that had a similar clypeal structure but had a punctate face. There was a collection from Ecuador that was like a large version of sexarticulata, with punctate face and large, subtriangular clypeal projection. I examined specimens from several cloud forest sites in southern Mexico, collected by Bob Anderson; they are similar to Costa Rican humilis, but differ in larger size and having 8-segmented antennae (I have given these Mexican specimens a separate morphospecies code, JTL-007).
Type data
Discothyrea humilis Weber 1939:100. Two syntype dealate queens: Panama, Barro Colorado Island (Weber). "One female was found among decayed leaves and humus on a fallen log, the other in debris swept down by a swollen stream from the forest." [MCZC] (one syntype queen examined). Measurements: HW 0.347, HL 0.379.
The type of humilis matches very closely the Costa Rican material I identify as humilis.
Similar taxa: icta
Discothyrea icta Weber 1939:101. Two syntype dealate queens: "two dealate females taken by myself under leaves at the base of a saman tree (Pithecolobium saman) on the grounds of the Imperial College of Tropical Agriculture, St. Augustine, Trinidad, B.W.I., August 3, 1935." [MCZC] (examined). Measurements: HW 0.364, HL 0.406.
I have examined the types of humilis and icta side by side, and can find no substantial difference.
Literature Cited
Weber, N. A. 1939. New ants of rare genera and a new genus of Ponerine ants. Ann. Entomol. Soc. Am. 32:91-104.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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