Chasmogenus lilianae, 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 : 489-491

Chasmogenus lilianae sp. nov.

(Figs. 5, 6, 16, 17 and 24)

Type material. Holotype (male): “ BRASIL: Rio de Janeiro,/ Nova Friburgo,/ Macaé de Cima,/ Tributário de 1a Ordem/ do Rio Macaé/ 13.IX.2009,/ Casa amarela, campo/ das hortênsias/ 22°25’36.5”S 42°31’56.4” O,/ Clarkson, B. col.” ( DZRJ, Coleoptera 3176); Paratypes (3): BRAZIL: Rio de Janeiro State: Nova Friburgo Municipality: Same as Holotype (3 ex.: DZRJ, Coleoptera 2932 ).

Diagnosis. Medium to large size species (3.80–4.55 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 developed, wide and semicircular (Figs. 16 and 17). General dorsal punctures of pronotum and elytra fine, much smaller than systematic punctures. Elytra with four weakly distinct longitudinal rows of systematic punctures in dorsal view (Fig. 5). Prosternum not carinate. Mesoventral carina restricted to posterior half, slightly raised (Fig. 6). Hind femora pubescent on basal nine-tenths (Fig. 6). Ventrite 5 with shallow apical emargination (Fig. 6). Phallobase short, manubrium distinct, narrow. Parameres as long as median lobe, inner margin slightly emarginated on apical three-tenths, outer margin slightly concave. Median lobe thick, gradually narrowing apicad, apex blunt; basal apophyses slightly convex, within parameres (Fig. 24).

The new species can be distinguished from other Neotropical species meanly for the male genitalia characteristics (Fig. 24): for the phallobase wider on apical portion, near of the junction with the parameres; parameres as long as median lobe, with outer margin slightly concave and the median lobe apex blunt (by these last two characteristics it resembles C. itatiaia sp. nov.). Concerning South American species, C. lilianae sp. nov. 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. ubatuba sp. nov., is useful to distinguish these two species from the other Brazilian species.

Description. Holotype male.

Size and form. Total length 4.05 mm; maximum width 2.15 mm; maximum width of head 1.03 mm; elytral length 2.75 mm; maximum width of pronotum 1.85 mm. Body broadly oval, moderately convex (Fig. 5).

Color. Dorsum of head and elytra uniformly dark brown, pronotum slightly paler than head with lateral and anterior margins often paler than pronotal disk (Fig. 5). Antennae with antennomeres 1-5 pale brown, club brown (Fig. 6). Maxillary palpi brown, labial palpi pale brown (Fig. 6). Ventral face dark brown, brown in the posteromedial glabrous area and behind metafemur in the metaventrite; lateral part of pronotum and epipleuron brown; legs brown, dark brown on pubescent portion of femora (Fig. 6).

Head. Ground punctation on clypeus, frons and labrum very fine, distance between punctures 2.0–3.0× the width of one puncture. Systematic punctures on labrum consisting of several scattered punctures, somewhat larger than surrounding punctures, sometimes bearing short, fine setae. Clypeus with scattered distinct systematic punctures, mainly on anterolateral portion, about twice as large as surrounding punctures, bearing short, fine setae. Frons with irregular row of distinct systematic punctures along frontoclypeal suture, about 2.0–3.0x larger than surrounding punctures and some less distinct scattered systematic punctures mesally of eyes, both 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 as long as maximun width of head; apical palpomere subequal in length than penultimate palpomere, palpomere slightly longer than penultimate palpomere (1.3× as long as penultimate one) (Figs. 5 and 6). Labial palpi about half the width of mentum; ultimate palpomere with a preapical long seta (e.g. Fig. 12). Mentum bare, with some short setae on lateral margins, rather punctuate, somewhat rugose, with deep notch on anterolateral margin and deeply depressed on anterocentral half, anterocentral noth developed, wide and rounded, semicircular (Figs. 16 and 17).

Thorax. Ground punctation on pronotum and elytra evenly distributed and very fine. Pronotum with two anterolateral and two posterolateral series of systematic punctures with short fine setae, each systematic puncture at least 2.0x the size of surrounding ground punctures: anterior series forming an irregular row curved backwards, beginning near anterolateral corners 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. 5). Pronotal margins completely rimmed; lateral margins with sparse row of short setae, on anterior half; posterior margin slightly arcuate (Fig. 5). Elytra with four weakly distinct longitudinal irregular spaced rows of systematic punctures in dorsal view, punctures about 3.0–4.0x larger than ground punctures, bearing long, fine setae; sutural stria strongly impressed on posterior two-thirds (Fig. 5); Prosternum finely pubescent, weakly convex, not carinate medialy (e.g. Fig. 27). Mesoventrite with a longitudinal carina on medial part, restricted to posterior half, well defined but only slightly raised (Fig. 6). Metaventrite with posteromedial, enlongate oval glabrous area, twice longer than wide, about two-thirds of total length of metaventrite (Fig. 6). Hind femora almost totally pubescent (on basal nine-tenths) (Fig. 6).

Abdomen. Ventrites densely and evenly pubescent. Ventrite 5 with shallow apical emargination, distinctly wider than deep, and lined with coarse yellow setae (Fig. 6). Aedeagus (Fig. 24) about 0.54 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 apical portion; manubrium distinct, narrow, rounded at base, about half the length of phallobase. Parameres as long as median lobe, evenly wide from base to apical three-tenths, were gradually narrowing apicad, inner margin slightly emarginated on apical three-tenths in dorsal view, outer margin slightly concave; apex blunt, slightly turned inwards. Median lobe thick, gradually narrowing apicad, apex blunt; corona distinct, semicircular, wider than long, subapical (in apical fifth); basal apophyses slightly convex, within parameres, almost extended into phallobase.

Variation. Body length from 3.80 mm to 4.55 mm. Significant variation on coloration and sexual dimorphism in the external morphology was not observed in the type specimens.

Etymology. This species is dedicated to Dr. Liliana Alicia Fernández in recognition of her significant contributions to South American Hydrophiloidea studies.

Biology. All type material of C. lilianae sp. nov. was collected from standing water in a narrow groove about 30 cm of width, among submerged leaf litter, in a mountainous area about 940 m a.s.l.