Ptenidium gruenbergae sp.n. (Figs. 6 A–J) Length 0.80 mm. Dark, shining, appearing polished, with very short, barely visible, scattered pubescence. Antennomeres 3–8 length 0.33 mm, Fig. 6B. Head with longer pubescence and a group of much longer setae medially on the anterior margin, the central stouter ones appearing to form a bifid process, Fig. 6E. Width across eyes 0.32 mm. Mentum with rounded lateral margins, Fig. 6G. Pronotum length 0.24 mm, width 0.45 mm, with a small group of setae on the posterior margin at the corners, Fig. 6H; without any fovea on the anterior and posterior margins. Scutellum with a depression at the anterior corners and a short median keel with rounded margins, Fig. 6J. Elytra length 0.54 mm, width 0.47 mm. Proventral process parallel sided, rounded posteriorly and with a shallow median depression, Fig. 6F. Mesoventral collar and keel, Fig. 6I. Male: aedeagus Figs. 6 Ca/b. Female: spermatheca Fig. 6D. Etymology. Named after the collector Brigitte Grünberg (Berlin). Diagnosis. The only other described species in this subgenus, which is typified by the patches of setae on the pronotal posterior angles and the form of the genitalia, are from Peru. P. gruenbergae can be separated from those by the group of setae on the front margin of the head. Type data. Holotype: ♂, Costa Rica, Osa Peninsula, Road, Bahia Drake to Rincon de Osa, forest and plantations, car net devart, 8.41–42 N 83.29 –40W, 0–400m, 9.x.2012, 1500–1700 hrs, Schülke & Grünberg (INBio). Paratypes: 6 examples, same data as holotype (INBio, BMNH).

Published as part of Darby, Michael, 2016, New Species and Records of Costa Rican Featherwing Beetles (Coleoptera: Ptiliidae), pp. 41-51 in Zootaxa 4184 (1) on page 46, DOI: 10.11646/zootaxa.4184.1.2, http://zenodo.org/record/164467