Holotype (♂): “BRAZIL: Minas Gerais: Lassance; 17.83384S, 44.50515W; 568 m; Cachoeira da Palmeira; flotation of root mats and moss from side of waterfall & seepage; 2.iii.2018; leg. Benetti & team; BR18-0302-04A” (INPA). Paratypes (7): BRAZIL: Minas Gerais: Same data as holotype (INPA, SEMC, 7 including DNA voucher SLE 1506).

Ephydrolithushamadae is very similar to E.teli. Both species can only be distinguished from each other by characteristics of the aedeagus.

Body length 2.6–3.2 mm, width 1.5–1.7 mm. Body elongate oval, moderately convex (Fig. 5B). General coloration yellowish to dark brown, slightly paler along margins of pronotum and elytra. Posterior elevation of mesoventrite with well-defined, curved transverse ridge. Elytra without striae or serial punctures. Pro- and mesofemora covered with hydrofuge pubescence along basal 2/3; metafemora with hydrofuge pubescence on tibial grooves. Apex of fifth abdominal ventrite truncate (Fig. 7C). Aedeagus (Fig. 7D) with basal piece 0.6 × the length of parameres; parameres nearly 0.5 × greatest width of median lobe, with outer margins slightly sinuate; apex of parameres rounded, obliquely directed; apex of median lobe “pinched”, narrowly rounded.

Named after Neusa Hamada from the Instituto Nacional de Pesquisas da Amazônia, Manaus (INPA), in recognition of her support on recent expeditions collecting aquatic beetles in Brazil.

Known only from the type locality (Fig. 8).

This species was collected by gathering moss and roots from bottom and margin of a seepage that was next to a large waterfall (Fig. 9C). Specimens were collected by placing the moss and roots in a pan with water, where they floated to the surface along with one specimen of E.spiculatus.