Chasmogenus ubatuba, Clarkson, Bruno & Ferreira-Jr, Nelson, 2014

Clarkson, Bruno & Ferreira-Jr, Nelson, 2014, Four new species and first nominal record of Chasmogenus Sharp, 1882 (Coleoptera: Hydrophilidae) from Brazil, Zootaxa 3765 (5), pp. 481-494 : 491-492

Chasmogenus ubatuba sp. nov.

(Figs. 7, 8, 20, 21 and 25)

Type material. Holotype (male): “ BRASIL: São Paulo, Ubatuba ,/ Parque Estadual da Serra do Mar,/ Núcleo Picinguaba/ 26.X.2000, poça na/ estrada para a casa da farinha/ 23°20'56.33"S 44°51'2.18" O / Ferreira-Jr, N. col.” ( DZRJ, Coleoptera 3177); Paratypes (23): BRAZIL: São Paulo State: Ubatuba Municipality: Same as Holotype, different dates and leg.: “ 04.VI.2000, Carvalho, A. L. col.”; “ 26.X.2000, Ferreira-Jr, N. col.”; “ 29.VI.2006, Ferreira-Jr, N. & Braga, R. B. col.” (13 ex.: DZRJ, Coleoptera 1772 , 1773, 2560; 2 ex.: SEMC; 2 ex.: MLPA; 2 ex.: MNRJ; 2 ex.: NHMW; 2 ex.: NMPC).

Diagnosis. Medium to large size species (4.80–5.50 mm). Head densely punctated. Anterior clypeal margin with narrow emargination, round to angulate shaped, exposing a gap between clypeus and labrum (e.g. Fig. 28). Anterior margin of labrum slightly concave medially. Anterocentral notch on mentum developed and subtriangular (Figs. 20 and 21). General dorsal punctures of pronotum and elytra moderately coarse, only slightly smaller than systematic punctures. Elytra with four quite indistinct longitudinal rows of systematic punctures in dorsal view (Fig. 7). Prosternum with slight carina on posterior portion (e.g. Fig. 29). Mesoventral carina very weak, restricted to posterior half (Fig. 8). Hind femora pubescent on basal nine-tenths (Fig. 8). Ventrite 5 with shallow posteromedial emargination (Fig. 8). Phallobase short, manubrium distinct, very narrow. Parameres shorter than median lobe, inner margin emarginated on apical three-tenths, outer margin sinuate. Median lobe narrow, wider at base, gradually narrowing apicad, apex slightly acuminate. Basal apophyses subparallels, within parameres (Fig. 25).

Considering the body length range among the species described in the genus, as well as C. fluminensis sp. nov., C. ubatuba sp. nov. may be considered a medium to large species. As only C. itatiaia sp. nov. presents larger specimens, the total length may help to diagnose the species. The new species can be distinguished from other Neotropical species meanly for the characteristics of the remarkable male genitalia (Fig. 25): as manubrium very narrow, parameres with inner and outer margins sinuate, median lobe narrow, wider at the base, gradually narrowing apicad with apex slightly acuminate. Concerning South American species, C. lilianae present anterior clypeal emargination narrow and rounded to angulate (e.g. Fig. 28), as well as all Brazilian new species, C. bariorum , C. occidentalis , C. yukparum and C. rufinasus , differing this species from C. australis and C. sapucay , which present this emargination wide with its mesal portion straight (e.g. Fig. 30). The absence of a strong carina raised into a “tooth” on metaventrite differ this species, as well as all described species here, from Venezuelan species C. bariorum , C. occidentalis and C. yukparum . Hind femora almost totally pubescent (on basal nine-tenths) (Fig. 6), characteristic shared with C. lilianae sp. nov., is useful to distinguish these two species from the other Brazilian species.

Description. Holotype male.

Size and form. Total length 5.40 mm; maximum width 2.90 mm; maximum width of head 1.30 mm; elytral length 3.50 mm; maximum width of pronotum 2.45 mm. Body broadly oval, moderately convex (Fig. 7).

Color. Frons dark brown, clypeus brown, labrum brown basally and pale brown on apical half; Pronotum and elytra uniformly brown with anterior, lateral and posterolateral margins of pronotum paler (Fig. 7). Maxillary and labial palpi pale brown. Antennae with antennomeres 1-5 pale brown, club brown (Fig. 8). Ventral face brown, darker in lateral portion of ventrites; legs brown, with pubescent portion of femora dark brown and tarsus pale brown apically (Fig. 8).

Head. Ground punctation on clypeus, frons and labrum moderately coarse, finer on labrum, about 1.0–2.0x the width of one puncture, coarser on clypeus and frons, about 0.5–1.5x the width of one puncture. Systematic punctures on labrum consisting of several punctures about twice the diameter of surrounding punctures, forming an irregular roll on median portion. Clypeus with an irregular row of distinct systematic punctures on both anterolateral portion, and some scattered ones, about 3.0x larger than surrounding punctures, bearing short, fine setae. Frons with irregular row of distinct systematic punctures along frontoclypeal suture at both sides and some scattered systematic punctures mesally of eyes, both about 2.0-3.0x larger than surrounding punctures and bearing short, fine setae. Anterior clypeal margin with narrow emargination, round to angulate shaped, exposing a gap between clypeus and labrum (e.g. Fig. 28). Anterior margin of labrum slightly concave medially. Mandibles bifid at apex. Maxillary palpi somewhat longer than maximum width of head (1.2x longer); apical palpomere slightly shorter than penultimate palpomere (1.1x shorter), palpomere 2 subequal in length to penultimate palpomere (Fig. 7 and 8). Labial palpi about 0.6x the width of mentum; ultimate palpomere with a preapical long seta (e.g. Fig. 12). Mentum bare, rather punctuate, rugose, with deep notch on anterolateral margin and deeply depressed on anterocentral half, anterocentral notch developed and subtriangular (Figs. 20 and 21).

Thorax. Ground punctation on pronotum and elytra evenly distributed and moderately coarse. Pronotum with two anterolateral and two posterolateral series of systematic punctures with long fine setae, each systematic punctures at least 2.0x the size of surrounding ground punctures: anterior series forming an irregular dense row curved backwards, beginning near anterior corners of pronotum going toward medial portion of pronutum; posterior series forming an irregular row on posterior half, perpendicular to lateral margins, beginning near of margin, restricted to lateral quarter (Fig. 7). Pronotal margins completely rimmed; lateral margins with sparse row of setiferous punctures, on anterior two-thirds; posterior margin slightly arcuate (Fig. 7). Elytra with four longitudinal irregular spaced rows of systematic punctures in dorsal view, these punctures are slightly larger than ground punctures, sometimes only distinguishable by bearing rather long, fine setae; inner row with punctures deeply impressed on posterior third; lateral portion with large irregular field of these systematic punctures; outer margin with a distinct row of systematic punctures regularly spaced; sutural stria strongly impressed on posterior half (Fig. 7). Prosternum finely pubescent, weakly convex, with a slight carina on posterior portion (e.g. Fig. 29). Mesoventrite slightly convex medially on posterior half, with a very weak, longitudinal carina on medial part (Fig. 8). Metaventrite with posteromedial, enlongate oval glabrous area, slightly longer than wide; glabrous area about two-thirds the total length of metaventrite (Fig. 8). Hind femora almost completely pubescent (on basal ninetenths) (Fig. 8).

Abdomen. Ventrites densely and evenly pubescent. Ventrite 5 with shallow posteromedial emargination, distinctly wider than deep, and lined with coarse yellow setae (Fig. 8). Aedeagus (Fig. 25) about 0.77 mm in length. Phallobase well developed, as long as wide, symmetrical, shorter than apical portion (ca. 0.30x the aedeagus in length), maximum width on medial portion; manubrium distinct, very narrow, rounded at base, about half the length of phallobase. Parameres shorter than median lobe, evenly wide from the base to apical half, where narrows abruptly, inner margin emarginated on apical three-tenths in dorsal view, outer margin sinuate; apex ronded, slightly turned inwards. Median lobe narrow, wider at the base, gradually narrowing apicad, apex slightly acuminate; corona distinct, oval, wider than longer, subapical (on apical third); basal apophyses subparallels, within parameres, almost extended into phallobase.

Variation. Body length from 4.80 mm to 5.50 mm. Significant variation in coloration and sexual dimorphism in the external morphology was not observed in the type specimens.

Etymology. The species name refers to the Ubatuba Municipality in São Paulo State, from where the type specimens were collected. Noun in apposition.

Biology. All type material of C. ubatuba sp. nov. was found among the vegetation and submerged leaf litter, in a ditch of about 1m wide, along an unpaved road in the border of the forest in the Atlantic rain forest region, at sea level.