Oocyclus thrixdiastematus, Alencar & Short & Hamada, 2022

Alencar, Janderson Batista R., Short, Andrew Edward Z. & Hamada, Neusa, 2022, New species and new distributional records of the hygropetric water scavenger beetle genus Oocyclus Sharp (Coleoptera, Hydrophilidae) from the Brazilian Shield, Zootaxa 5087 (2), pp. 275-305 : 293-295

publication ID

https://doi.org/ 10.11646/zootaxa.5087.2.3

publication LSID




persistent identifier


treatment provided by


scientific name

Oocyclus thrixdiastematus

sp. nov.

Oocyclus thrixdiastematus View in CoL sp. n.

( Figs. 8a–d View FIGURE 8 , 11h View FIGURE 11 , 12b View FIGURE 12 , 14 View FIGURE 14 )

Type material. Holotype (male): “ BRASIL: MINAS GERAIS, PARNA Serra do Cipó, Waterfall Capão dos Palmitos, long -43.6096, lat -19.3775, 830 m a.s.l., rock-face seepage, 8.vi.2019, leg. J.B. R. Alencar ” ( INPA, Coleoptera , in alcohol) . Paratypes (30 exs.): BRAZIL: Minas Gerais: Same data as holotype (5 exs. INPA , in alcohol); except: “Waterfall of Andorinhas, long -43.4915, lat -19.2376, 577 m a.s.l., rock-face seepages, 10.vi.2019, leg. J.B. R. Alencar” (1 ex. INPA , in alcohol);”Canyon of the Bandeirinhas, long -43.5627, lat -19.4239, 880 m a.s.l., seepage habitat, 11.vi.2019, leg. J.B. R. Alencar” (3 exs. INPA , in alcohol); “ PARNA Serra do Gandarela, Waterfall of Mingu, long -43.7596, lat -20.0622, 1006 m a.s.l., rock-face seepages, 15.vi.2019, leg. J.B. R. Alencar” (2 exs. INPA , in alcohol); “ Parque Estadual Serra do Cabral , Waterfall of Demir , long -44.212 lat -17.9204, 833 m a.s.l., rock-face seepages, 14.iv.2019, leg. J.B. R. Alencar” (2 exs. INPA , in alcohol); “ Diamantina, Waterfall of Andorinhas, long -43.5949 lat -18.2309, 1168 m a.s.l., 11.iv.2019, leg. J.B. R. Alencar” (1 ex. INPA , in alcohol); “Lassance, Waterfall of Palmeiras , long -44.5042, lat -17.8343, 520 m a.s.l., vertical surfaces with water, 1.v.2019, leg. J.B. R. Alencar” (8 exs. INPA , in alcohol); Goias: “Alto Paraíso de Goiás, Waterfall da muralha, long -47.7507, lat -14.2774, 957 m a.s.l., 2.VII.2019, leg. J.B. R. Alencar” (4 exs. INPA ; 4 exs. SEMC, in alcohol) .

Diagnosis. Medium-sized species. Pronotum with rounded posterolateral margins. Elytra surface even, with rows of systematic punctures present, but merging with ground punctation, both (ground punctures and systematic punctures) bearing fine setae, appearing pubescent in dorsal view and each elytron with two small pale circular spots. Elytra sutural interval not raised ( Fig. 12b View FIGURE 12 ). Prosternum with two anteromedial spine-like setae. Abdominal ventrites dark brown, not paler than thoracic ventrites.

Adult. Body length 4.0– 4.7 mm (n= 10, mean= 4.55, SD= ±0.23); TL/GW 1.65± 0.09 mm. General body shape broadly oval, slightly convex.

Color. Dorsum black ( Fig. 9a View FIGURE 9 ), covered with dense, irregular green or bronze sheen. Anterolateral margins of pronotum with pale strip, extending to ca. 2/3 of lateral margin length. Elytra with irregular patches of bronze or green iridescence; with row of rounded black [=without sheen] spots along suture. Each elytron with two small circular pale spots: anterior spot on distal third, about twice as far from suture than posterior spot; posterior spot situated on distal quarter. Antennae yellowish brown. Maxillary palps and labial palps yellow. Ventral face of head dark brown to black. Lateral margins of prosternum; pseudoepipleura and epipleura yellowish brown. Thorax dark brown to black ventrally. Legs light brown to yellow, except for dark brown coxae and basal region of femora. Abdominal ventrites dark brown, with slightly lighter posterior margins on ventrites1–4, sometimes with pale patches laterally on ventrites 2–3.

Head. Ground punctation on clypeus and frons moderately coarse, distance between punctures 2.0–3.0× width of one puncture ( Fig. 9d View FIGURE 9 ). Ground punctation on labrum denser than punctation of clypeus, distance between punctures 0.5–1.5× width of one puncture; with few distinct systematic punctures medially. Labrum sometimes bearing short setae. Clypeus with several scattered indistinct systematic punctures laterally; and sometimes bearing short setae. Frons with irregular row of systematic punctures toward the median plane of each eye and few fine setae around ocular suture. Maxillary palps shorter than width of labrum; segment 3 shorter than segment 2; apical segment longer than penultimate segment. Labial palps about two-thirds as long as width of mentum. Mentum smooth, with scattered coarse punctures; subquadrate, anterior margin slightly convex and depressed.

Thorax. Ground punctation on pronotum and elytra evenly distributed and moderately coarse ( Figs. 9a, c, d View FIGURE 9 ). Pronotal systematic punctures with short fine setae, at least 2× size of surrounding ground punctures; the anterior and posterior series each forming an irregular field. Lateral margins of pronotum with fine setae distributed along its length, being more densely pubescent in the anterior half. Pronotal posterolateral angles rounded. Sutural interval on elytra not raised. Elytral interval with prominent pubescence on ground punctation ( Fig. 12b View FIGURE 12 ). Rows of systematic punctures on elytra present but not larger than surrounding ground punctuation and as such hardly distinguishable, blending uniformly with ground punctuation. Elytral surface without shallow longitudinal depressions medially on posterior half. Humeral region (in frontal view) without anteromedial elevation. Elytral margins with short spinelike setae situated along their length. Prosternum with a clearly defined median carina; slightly elevated anteromedially ( Fig. 9e View FIGURE 9 ); elevated region with two spine-like setae. Elevated process of mesoventrite wide and elongate, about twice as long as wide; slightly raised anteriorly; with 5–7 coarse spine-like setae. Metaventrite with posteromedial oval glabrous area ca. twice as long as wide; length of glabrous area about three-quarters length of metaventrite. Procoxae with fine short pubescence and set with coarse, short spine-like setae; grouped on basal half. Protibiae each with 6–7 spine-like setae on dorsal face. Meso- and metafemora with scattered punctures bearing short thickened, spine-like setae.

Abdomen. Ventrites covered with scattered, sparsely distributed setae of varying lengths; ventrites 1–4 with scattered, long setae, distinctly longer than longest setae on metaventrite, ventrite 5 more densely pubescent ( Fig. 9b View FIGURE 9 ). Aedeagus: outer margin of parameres weakly sinuous, gradually tapering to apex, curving inward; inner margin, straight, tapering from distal half (dorsal view); median lobe shorter than parameres, without apical hook. Gonopore located at medial half of median lobe. Basal piece tapered ( Fig. 11h View FIGURE 11 ).

Etymology. The specific epithet thrixdiastematus is a combination of the adjective thrix (G.), meaning “hairy” referring to the prominent pubescence on elytral intervals and the noun diastema (G.), meaning “space” or “interval” which refers to the location of pubescence on elytra. To be treated as a noun in apposition.

Distribution. Brazil (Bahia, Minas Gerais and Goias) ( Fig. 14 View FIGURE 14 ).

Remarks. This species shares with O. ecolab sp. n. the non-pale abdominal ventrites, elytral surface with rows of systematic punctures bearing short setae, each elytron with two small circular spots and two prosternal spines. However, both species can be distinguished by the following characters: O. ecolab sp. n. has the elytral interval with weak or non-existent pubescence in ground punctation; aedeagus with gonopore located at 4/5 the length on median lobe and the basal piece is rounded and short, while O. thrixdiastematus sp. n. has the elytral interval with dense pubescence, aedeagus with gonopore located at half on median lobe and the basal piece is tapered. The aedeagus of O. thrixdiastematus sp. n. is similar to that of O. pilosus Jordão, Clarkon & Ferreira-Jr, 2018 and co-occurs in at least some localities the same locality, but O. pilosus is easily distinguishable by the absence of the two spines-like setae in prosternum.


Departamento de Geologia, Universidad de Chile


Instituto Nacional de Pesquisas da Amazonia


University of Kansas - Biodiversity Institute













GBIF Dataset (for parent article) Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF