Hydrodessus latotibialis Miller, 2016 (Figs 3, 4, 7, 8, 12–14, 17) Material examined. Holotype (♀) labeled: “ PERU: Madre de Dios: Rio Tambopata Res: 30 km SW Pto. Maldo- nado, 290 m a.s.l., 16–20 XI 1979 J.B. Heppner subtropical moist forest / HYDRODESSUS sp. P.J.S. [handwritten] / HOLOTYPE Hydrodessus latotibialis Miller, 2016 [red label with black line border].” Paratype (♀) same data as holotype, except for having only locality label. (holotype and paratype deposited in USNM). Additional material examined: 2 ♂, 1 ♀: Brazil: Pará State, Paragominas County (03º46’55”S 048º30’43”W), 22.vii.2011, leg. J. Brito and V. Oliveira (INPA). Description. Measurements. TL = 2.9–3.2 mm, GW = 1.4–1.5 mm, PW = 1.2–1.3 mm, HW = 0.8–0.9 mm, EW = 0.5–0.6 mm, TL/GW = 2.0–2.1, HW/EW = 1.5–1.7. Male genitalia. Median lobe bilaterally symmetrical; in lateral aspect (Fig. 12) with basal portion broad, medially evenly and broadly curved, subapically strongly narrowed, then sinuate to sharply pointed apex; in ventral aspect (Fig. 13) robust and broad, lateral margins slightly divergent to broadened apical third, then converging towards slightly convex apex. Lateral lobes (Fig. 14) broad basally, distally gradually narrowed, apex rounded with series of short setae. Sexual dimorphism. Male pro- and mesotarsi I–III slightly broader than in female, ventrally with several large adhesive setae; male mesotibia apically broader than in female. Variation. Little variation was observed among specimens, mainly in pronotal and elytral coloration and in elytral maculae which are stronger in some specimens from Brazil. Distribution. Hydrodessus latotibialis is known from Brazil (Pará) and Peru (Madre de Dios) (Miller 2016) (Fig. 17). Habitat. Type specimens were collected from subtropical moist forest (Miller 2016). Specimens from Brazil were collected in a shaded forest stream, at 107 m a.s.l. Discussion. According to Miller (2016) this species has indistinct pale areas on elytra. However, we examined the holotype and the single paratype of H. latotibialis and found that the elytra have pale, somewhat diffuse but distinct yellow maculae basally, laterally, subapically and at apex, similar to H. maculatus Miller, 2016. Hydrodessus latotibialis is similar to H. maculatus, H. phyllisae Spangler, 1985 and H. tenuatus Miller, 2016 but differs from these species in the shape of the male median lobe, which in lateral view is medially evenly and broadly curved, subapically strongly narrowed, then sinuate to sharply pointed apex; in ventral view with lateral margins slightly divergent to broadened apical third, then converging towards apex. In addition, H. latotibialis differs from H. maculatus, H. phyllisae and H. tenuatus in having the apices of metaventrite carinae located well mediad to the anterior apices of metacoxal lines (metaventrite carinae and metacoxal lines approximately continuous in those species). The distance between the type locality from Peru and the new record from Brazil is surprising but not uncommon, since a similar distribution pattern is observed in other Hydrodessus species (e.g. H. keithi Miller, 2016).

Published as part of Benetti, Cesar J., Michat, Mariano C. & Hamada, Neusa, 2020, Hydrodessus ducke sp. n. and new records of other species of the genus (Coleoptera, Dytiscidae, Bidessini), pp. 47-60 in Zootaxa 4743 (1) on pages 49-50, DOI: 10.11646/zootaxa.4743.1.4, http://zenodo.org/record/3687626