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Key to Lachnomyrmex species known from Costa Rica

10a. Gaster with long flexuous setae at least on anterior third, usually over entire surface: 20

10b. Gaster devoid of erect setae: 30

20a. Weber's length around 0.7mm; metanotal groove not impressed: scrobiculatus

20b. Weber's length about 1.0mm; metanotal groove impressed; erect setae very dense and relatively shorter on first gastral tergum: JTL-005

20c. Weber's length about 1.0mm; metanotal groove impressed; erect setae relatively sparser and longer on first gastral tergum: JTL-004

30a. Dorsum of postpetiole irregularly rugose, without a raised triangular boss medially, and with more than 10 evenly distributed erect setae; dorsum of mesosoma with irregular short rugae: plaumanni

30b. Dorsum of postpetiole with a raised, subtriangular boss medially, and with a single row of about 6 long flexuous setae along anterior margin; dorsum of mesosoma with rugae organized into somewhat continuous wavy rugae, transverse on anterior pronotum, grading to longitudinal on rest of promesonotum: haskinsi

Queens: (the queen of JTL-005 is unknown)

10a. Weber's length about 1.3mm: JTL-004

10b. Weber's length less than 1mm: 20

20a. First gastral tergum uniformly covered with long flexuous setae: scrobiculatus

20b. First gastral tergum with erect setae sparse to absent on posterior half: 30

30a. First gastral tergum with about 50 long erect setae on anterior half; postpetiole dorsum irregularly rugose, without raised subtriangular boss medially: plaumanni

30b. First gastral tergum with about 10 long erect setae, in an anterior band near the postpetiolar insertion; postpetiole dorsum with a raised subtriangular boss medially: haskinsi

Some relevant papers:

Borgmeier, T. 1957. Myrmecologische Studien, I. Anais da Academia Brasileira de Ciencias 29:103-128.

Smith, M. R. 1944. The genus Lachnomyrmex, with the description of a second species. Proceedings of the Entomological Society of Washington 46:225-228.

Weber, N. A. 1950. New Trinidad myrmicinae, with a note on Basiceros Schulz (Hymenoptera, Formicidae). American Museum Novitates 1465:1-6.

Page author: John T. Longino longinoj@evergreen.edu