Haliplus regili sp. n.

(Figs. 3–4, 13–20)

Type locality. Brazil: Roraima state, Alto Alegre county, pond near the RR-205 road (02°59'39.8"N 61°06'46.2"W).

Type material. Holotype male (INPA): Brazil: Roraima state, Alto Alegre county, pond near the RR-205 road (02°59'39.8"N 61°06'46.2"W), 05.vi.2015, leg. C.J. Benetti, K. Dias-Silva and B.G. Oliveira.

Diagnosis. Haliplus regili sp. n. can be distinguished from other neotropical species of Haliplus by the following combination of characteristics: elytra brown with extensive but not clearly defined maculation consisting of dark patches (Fig. 3); prosternal process gradually widening anteriorly, slightly narrowed in posterior part; about 1.9 times longer than wide at base (Fig. 16); metaventral process with two well-defined impressions on both sides (Fig. 4) and median lobe of aedeagus in lateral view curved, straight in the apical third, with the apex strongly truncated (Fig. 19).

Description. Habitus (Fig. 3). Body oval, tapering backwards, widest just behind the shoulders, with very narrow pronotum and shoulders pronounced.

Measurements (n=1). TL: 3.36 mm; MW: 2.13 mm; PL: 0.7 mm; PW: 1.45 mm; DE: 0.26; EW: 0.25 mm.

Head. Orange-brown with vague darkening near antennae and between eyes; strongly and densely punctured; narrower than pronotum, widest across eyes; width between eyes 0.9 × width of eye. Antennae yellow; placed anterior to eyes; with 11 antennomeres, 1st and 2nd short and broad, 3–11 long, 11th the largest (Fig. 13). Palpi yellow; maxillary palpi with four palpomeres, the last shorter than penultimate. Genal lines behind eyes double.

Pronotum. Reddish-brown, with two vague dark spots at base; strongly and densely punctured, more strongly impressed along base; widest at base, narrow towards apex; lateral sides convex, not margined; base without plicae.

Elytra. Brown, with extensive but not clearly defined maculation consisting of dark patches; dark marks along suture and base not darkened (Fig. 3). Primary puncture rows strongly impressed at base and finely impressed at apex; about 33 punctures in first row; fifth elytral puncture row not extended along base; secondary puncture rows dense and moderately strong, along suture strong, in two irregular rows; all punctures darkened (Fig. 14). Lateral margin completely bordered; shoulders weakly serrate; apical margin not serrate.

Ventral side. Reddish-brown, darkened towards coxae. Epipleura reddish-brown, with double row of strong punctures in anterior part and single row of weaker punctures in posterior narrowed part, reaching to the end of fifth sternite. Prosternum bordered anteriorly, strongly punctured in the middle. Prosternal process gradually widening anteriorly, slightly narrowed in posterior part; about 1.9 times longer than wide at base; anterior edge margined, laterally grooved; moderately strongly and densely punctured (Figs. 4, 16, 17). Metaventral process with two well-defined, but slightly confluent impressions on both sides, not impressed in the middle; moderately punctured (Fig. 16). Metacoxal plates reaching to the fifth sternite, densely punctured. Fifth and sixth sternites densely punctured; last sternite punctured only at base (Fig. 4).

Legs. Orange-brown to brown. Fore- and mid legs: femur basally narrowed, medially enlarged, surface covered with dense, coarse micropunctures; tibia with long hairs on inner margin, apically with two equal spurs; tarsi with 5 tarsomeres, the 5th longest, tarsal claws of equal length. Hind legs: coxal plates enlarged covering trochanter and most of the femoral region; femur broadest at apex; tibia slender with unequal apical spurs, setiferous striole on dorsal face of 1/5 × length and longer apical spur as long as the length of first tarsomere (Fig. 15); tarsi with 5 tarsomeres, 1st the longest, with a pair of equal claws.

Male. First three tarsomeres of fore- and midlegs widened and ventrally with a tuft of sucker hairs. Aedeagus: Median lobe in lateral view curved, straight in the apical third, wider at base, narrowed towards the apex and slightly widened at tip; apex strongly truncated (Fig. 19). Left paramere in lateral view short and broad, subtriangular, almost as long as wide, with basal process narrow, and with apex angular; with a series of long setae and some sparse setae at the apex (Fig. 18). Right paramere in lateral view slender, moderately curved, base bilobed, apex rounded; inner margin with a series of large setae in the apical two thirds (Fig. 20).

Etymology. This species is named in honor of Juan Antonio Régil Cueto, the PhD supervisor of the first author, a good friend and colleague, in gratitude for all the shared moments during our long friendship and in recognition of his contribution to the knowledge of water beetles.

Distribution and habitat. Northern Brazil, currently only known in the state of Roraima (Fig. 21). Specimen was collected in a shallow pond with macrophytes covering the entire surface (Fig. 23).

Taxonomic comments. Haliplus regili sp. n. can be distinguished from other neotropical species of Haliplus by the combination of characteristics of elytra, prosternal and metaventral processes and the male genitalia shape. The new species resembles H. langleyi Vondel & Spangler, 2008 and H. triplehorni Vondel & Spangler, 2008, but differs from these species in the shape of prosternal process (Fig. 16), gradually widening anteriorly (almost parallel in H. langleyi and H. triplehorni); male median lobe (Fig. 19), shorter and less curved downward in H. langleyi and H. triplehorni and right paramere (Fig. 20), without distal appendage (with distal appendage in H. langleyi and H. triplehorni .