Myrmelachista osa

Longino, J. T., 2006, A taxonomic review of the genus Myrmelachista (Hymenoptera: Formicidae) in Costa Rica., Zootaxa 1141, pp. 1-54: 42-43

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Myrmelachista osa


Myrmelachista osa   HNS   NEW SPECIES

Figures 1, 4, 7, 8, 9

Holotype alate queen: Costa Rica, Prov. Puntarenas, Rancho Quemado, Osa Peninsula , 8°42’N, 83°33’W, 200m , 15 Dec 1990 (J. Longino #2752) [ INBC, specimen code JTLC000006231]. GoogleMaps  

Paratypes: workers and queens, from same nest as holotype, specimen codes JTLC000006232 - JTLC000006236, distributed to MCZC, USNM, UCDC, LACM, BMNH. GoogleMaps  


Worker with antenna 9-segmented, maxillary palpus 5-segmented, color yellow. Queen black; mandible punctatorugose; face smooth and shining; sides of head with short appressed to suberect pubescence, no longer erect setae; maxillary palpus 6-segmented; CI 79-84.


Same as M. flavocotea   HNS   but with tendency to develop faint infuscated bands on gastral tergites.

Measurements: HL 0.518-0.521, HW 0.479-0.511, SL 0.256-0.265, EL 0.097-0.105, CI 92-98 (n=3).


Antenna 9-segmented; maxillary palpus 6-segmented; labrum short, bilobed, not covering mouthparts; dorsal surface of mandible punctatorugose; face and clypeus largely smooth, variably roughened anteriorly; in full face view, with abundant short suberect setae on rear and side margins of head, longer setae on posterolateral vertex; ventral surface of head with abundant short erect setae; scapes with abundant erect to suberect setae, longer setae subequal to width of scape; outer surface of hind tibia with abundant short subdecumbent setae, longer setae shorter than width of tibia; color solid black.

Measurements: HL 1.181-1.226, HW 0.971-0.997, SL 0.491-0.507, EL 0.283-0.303, OW 0.062-0.081, OD 0.173-0.185, CI 79-84, OI 28-31, OcI 5-7 (n=3).




The name refers to the Osa Peninsula, which is the type locality.


Costa Rica. In Costa Rica it occurs at Rancho Quemado on the Osa Peninsula.


This species is known from mature wet forest at Rancho Quemado on the Osa Peninsula. I collected it from three different Ocotea nicaraguensis   trees, and it appears to have a biology similar to M. flavocotea   HNS   and others.

Material Examined

COSTA RICA, Puntarenas: Rancho Quemado, Osa Peninsula , 8°42’N, 83°33’W, 200m (J. Longino, 3 collections). GoogleMaps  


Costa Rica, Santo Domingo de Heredia, Instituto Nacional de Biodiversidad (INBio)


USA, Massachusetts, Cambridge, Harvard University, Museum of Comparative Zoology


USA, Washington D.C., National Museum of Natural History, [formerly, United States National Museum]


USA, California, Davis, University of California, R.M. Bohart Museum of Entomology


USA, California, Los Angeles, Los Angeles County Museum of Natural History


United Kingdom, London, The Natural History Museum [formerly British Museum (Natural History)]