Holotype (male): “PERU: Madre de Dios: Parque Manu, Pakitza/ 12°07'S 70°58'W/ R.A. Faitoute, colln 32/ 250 m, stream/ Trocha Dos, c72/ 10 Sept 1989” (USNM). Paratypes (39): PERU: Madre de Dios: Same data as holotype (14, SEMC, USNM); same, except “colln 32a, berlesed leaf litter” (12, SEMC, USNM); same, except “11–15 Sept 1989, colln 35a, Trocha uno, c 11, flight intercept trap in dry narrow stream bed” (2, USNM); same, except “16 Sept 1989, colln 42a, Trocha Dos, c.53, berlesed leaf litter” (2, USNM), same, except “18 Sept 1989, colln 46, Trocha Dos, c 14, spring seepage” (4, USNM, SEMC); same, except “19 Sept 1989, colln 47, Trocha Uno, c 14, stream” (2, USNM); same, except “colln 47a, berlesed leaf litter” (2, USNM); same, except “22 Sept 1989, coll 55a, TC 22, berlesed leaf litter & root mats” (1, USNM).

Katasophistes charynae is very similar to K. cuzco, from which it can be distinguished by its smaller size, generally darker coloration, simple curved transverse ridge on the posterior elevation of mesoventrite and characters of the aedeagal parameres.

Body length 2.6 to 3.5 mm, width 1.5 to 1.9 mm. Body elongate oval, weakly convex (Fig. 9B). General coloration uniformly dark brown, with slightly paler margins of pronotum. Each elytron with five rows of shallow enlarged systematic punctures. Posterior elevation of mesoventrite with well-defined, curved, uniformly wide transverse ridge. Apex of fifth abdominal ventrite weakly emarginate (Fig. 11D). Aedeagus (Fig. 12A, B) with basal piece 0.4 to 0.5-times the length of parameres; greatest width of parameres near base, clearly wider than pre-apical width, with inner margin sinuate, at widest point, parameres nearly 0.7-times greatest width of median lobe; apex of parameres rounded, slightly widened at apex; apex of median lobe forming an acute angle.

Named after Charyn Micheli (USNM), Coleopterist and museum specialist in charge of the aquatic beetle collection (among others) at the Smithsonian Institution who has assisted the authors on numerous occasions and diligently oversees the largest water beetle collection in the world.

Peru (Madre de Dios). See Fig. 13.

Most specimens were collected in streams.

There is variation in the relative proportions of the aedeagus and the shape of the parameres, with some specimens having a wider and shorter aedeagus (Fig. 12A), and some with a more slender aedeagus bearing slender parameres (Fig. 12B). As there are no external features to distinguish them, and both forms of aedeagi were found at the same localities, we refrain from calling them different species until more material and/or possibly molecular data are available.