Berosus parvus, Santana & Benetti & Clarkson & Pes, 2019

Santana, Larissa, Benetti, Cesar João, Clarkson, Bruno & Pes, Ana Maria, 2019, On the genus Berosus Leach (Coleoptera: Hydrophilidae) in the State of Roraima Brazil: description of three new species and new records, Zootaxa 4700 (4), pp. 445-463 : 456-457

Berosus parvus sp. n.

( Figs. 6 a–h)

Type locality. BRAZIL: Roraima State, Boa Vista municipality, pond near the “Estrada do Contorno” road (02°47’15.4’’ N / 60°46’37.3’’W) ( Fig. 3 ) .

Type material. Holotype male. BRAZIL: Roraima State: Boa Vista County (02°47’15.4’’N / 60°46’37.3’’W), 01.vi.2015, leg. K. Dias, C. Benetti. Condition of holotype: stored in 80% ethanol with the dissected male genitalia stored in microvials with glycerin, deposited at INPA . Paratypes (6). BRAZIL: Roraima State: Same data as holotype, except (02°54’36.5’’N / 60°57’30.9’’W), 03.vi.2015 [2 males stored in 80% ethanol, deposited at INPA]; same data as holotype, except (02°52’29.7’’N / 60°51’48.9’’W), 05.vi.2015 [1 male stored in 80% ethanol, deposited at MZSP]; same data as holotype, except (03°10’53.9’’N / 60°50’00.8’’W), 07.vi.2015 [1 male stored in 80% ethanol, deposited at MNRJ]; Alto Alegre County (02°59’48.7’’N / 61°07’48.7’’W), 05.vi.2015 [1 male stored in 80% ethanol, deposited at SEMC]; Alto Alegre County (02°51’13.7’’N / 60°50’32.8’’W), 02.vi.2015 [1 male stored in 80% ethanol, deposited at DZUP] .

Diagnosis. Berosus parvus sp. n. can be distinguished from other Neotropical species of Berosus by the following combination of characteristics: small size (2.40–2.50 mm); clypeus yellow with small dark brown triangle on the middle of posterior margin, frons entirely dark brown or with large dark-brown spot on the median area; pronotum yellow with one discal dark-brown spot and elytra yellow with small dark-brown spots, without metallic luster ( Fig. 6a ); pronotum with fine, round punctures ( Fig. 6a ); elytral, striae well-impressed with round punctures ca. 2× as large as those on the pronotum ( Fig. 6a ); mesoventral process laminar with very short curved anterior tooth, directed downwards and backwards, with smooth margins ( Fig. 6d ); abdominal ventrites not crenulate along lateral margins, posterior margins crenulate; first ventrite medially carinate along its whole length; fifth ventrite with apical notch ca. one-quarter the total length, bearing a single short median tooth ( Fig. 6e ).

Description. Size and form. Total length: 2.44–2.47 mm. Body short, nearly 2.2× longer than wide in dorsal view ( Fig. 6a ), moderately convex in lateral view ( Fig. 6b ).

Color. Labrum slightly yellow; clypeus yellow with small dark-brown triangle on the middle of posterior margin; frons entirely dark brown or with a large dark-brown spot on median area, without metallic luster ( Figs. 6a ); maxillary palpi yellow with fourth palpomere dark brown at apex ( Figs. 6 a–c); pronotum yellow, with one discal dark-brown spot without metallic luster; scutellar shield slightly darkened ( Fig. 6a ); elytra yellow with small dark brown spots ( Fig. 6a ); venter of thorax and abdomen dark brown ( Fig. 6c ); femora, tibiae and tarsus entirely yellow ( Figs. 6 a–c).

Head. Clypeus and frons sparsely and finely punctate, punctures ca. 2× as large as ommatidia, round in shape ( Fig. 6a ). Frontal carina absent. Eyes slightly prominent ( Fig. 6a ). Maxillary palpi short, nearly half as long as width of the head, and thick ( Figs. 6 a–c).

Thorax. Posterior margin of pronotum about as wide as basal margin of elytra, with fine, round, and moderately dense punctures, the same size as those on head, slightly coarser along sides ( Fig. 6a ). Scutellar shield densely punctate with punctures similar in size to those on elytra. Elytral striae well-impressed with round punctures ca. 2× larger than those on pronotum; interstriae flat on elytral disc, ca. 2× as wide as striae, sparsely and finely punctate (punctures smaller than those on pronotum); humeral hump not prominent ( Fig. 6a ); elytral apices rounded ( Figs. 6 a–c); spine-like hairs absent ( Fig. 6a ). Mesoventral process laminar with very short, curved anterior tooth, directed downwards and backwards with smooth margins; posterior angle of the mesoventral process weakly raised in lateral view, not prominent ( Fig. 6d ). Metaventral process narrow, carinate before median depression, posterolateral angles produced into small rounded laminae; posterior angle not raised ( Fig. 6c ). Basal pubescence on two-thirds of mesofemora and three-fourths of metafemora, limit oblique ( Fig. 6c ). Protarsus of male with adhesive soles in tarsomeres 1–2, first tarsomere ca. 1.5× longer than second, fourth tarsomere elongate, almost as long as tarsomeres 1–3 combined ( Figs. 6a, c ). Claws weakly arched ( Figs. 6 a–c).

Abdomen. First ventrite medially carinate its whole length, without lateral depressions; abdominal ventrites 2–4 without central carina or tooth-like projection, not crenulate along lateral margins; posterior margins crenulate; fifth ventrite with apical notch ca. one-quarter the total length, bearing a single short median tooth ( Fig. 6e ). Aedeagus compressed laterally with basal piece ca. three-quarters of total length, 2.4× longer than its greatest width ( Figs. 6 f–h); parameres symmetrical, as long as median lobe in dorsal view, subcylindrical ( Fig. 6f ); apical portion of parameres curved towards ventral face, obliquely directed regarding dorsal outline of aedeagus in lateral view, bearing a ventral row of short hairs along subapical portion ( Figs. 6g, h ); median lobe cylindrical, not swollen subapically, apex with small hole in the median region in dorsal view ( Fig. 6f ).

Etymology. The specific epithet, parvus , refers to the very small size of specimens (From Latin “ parvus ”, little, small).

Distribution. Brazil (Roraima).

Biology. The specimens were collected in ponds with abundant macrophyte cover ( Figs. 1, 2 ).

Taxonomic comments. B. parvus sp. n. can be placed in the sticticus -complex ( Oliva 1989; Oliva & Short 2012), based on the following characteristics: dorsal sculpture fine (varying from coarse to fine in the complex); elytra with humeral humps not prominent and without spine-like hairs; abdominal ventrites medially carinate behind metacoxae without lateral depressions in first ventrite; protarsus of males with soles on the two basal tarsomeres, which are weakly swollen (weakly to moderately swollen in the complex); and male genitalia on which the aedeagus is somewhat compressed laterally, with parameres parallel and acuminate, with median lobe weakly curved (strongly or weakly curved in the complex). The new species is similar to B. olivae Queney, 2006 by the body length, dorsal coloration and shape of the apical emargination of the fifth ventrite, but they can be differentiated by the shape of male genitalia. In B. parvus sp. n. the aedeagus is subcylindrical in dorsal view ( Fig. 6f ) and sigmoidal in lateral view ( Fig. 6g ); the basal piece corresponds to ca. three-quarters of the total length ( Figs. 6g, h ); the median lobe is cylindrical and has a hole at apex ( Fig. 6f ); in B. olivae , the aedeagus gradually narrows along its distal third; the basal piece corresponds to a little more than half the total genitalia length. B. parvus sp. n. is also similar to B. subandinus Oliva, 1989 by the shape of the male genitalia in lateral view and length of the basal piece, but B. parvus sp. n. has wide parameres in the distal three-quarters of its length ( Figs. 6 f–h), while in B. subandinus the parameres are narrow and have a marked notch in the distal 4/5 of its length. In addition, B. parvus sp. n. has a narrow metaventral process, which is carinate before the median depression with posterolateral angles produced into small rounded laminae ( Fig. 6c ) and the apical emargination of the fifth abdominal ventrite bears a single medial tooth ( Fig. 6e ), while B. subandinus has a wide metaventral process with posterolateral angles not produced and apical emargination of the fifth abdominal ventrite with two teeth in the medial region. The new species is similar to B. guyanensis in dorsal coloration, punctuation of the head, pronotum, elytra and shape of mesoventral process. However, B. parvus sp. n. has the first abdominal ventrite carinate along its entire length medially and apical emargination of the fifth abdominal ventrite with a single medial tooth ( Fig. 6e ), while B. guyanensis has the first abdominal ventrite carinate on anterior one-third and apical emargination of the fifth abdominal ventrite with two medial teeth. In addition, B. parvus sp. n. has a subcylindrical aedeagus with the same thickness from base to apex ( Figs. 6f, h ), basal piece reaching three-quarter of the total length ( Figs. 6 g–h) and parameres with the same length as the median lobe ( Fig. 6f, h ), while in B. guyanensis the male genitalia narrows abruptly at four-fifths of total length, the basal piece reaches four-fifths of total length and the parameres are larger than the median lobe. The species also similar to B. sticticus Boheman, 1859 , but differs from this species by the shape of the mesoventral process, carina of first ventrite and apical notch of fifth abdominal ventrite. B. parvus sp. n. has the mesoventral process with very short, curved anterior tooth, directed downwards and backwards, posterior angle weakly raised in lateral view, not prominent ( Fig. 6d ), while B. sticticus has a mesoventral process with a large and wide tooth, directed downwards and prominent posterior angle in lateral view. In addition, B. parvus sp. n. has the first ventrite medially carinate in its whole length and the fifth ventrite has apical notch with single short median tooth ( Fig. 6e ), while B. sticticus the first ventrite is carinated in the anterior third and the apical notch of the fifth ventrite has two adjacent teeth. These species also differ in the shape of the male genitalia, in B. parvus sp. n. the length of the basal piece is three-quarters of the total length ( Figs. 6g, h ) and the median lobe is as long as the parameres ( Figs. 6f, h ), while in B. sticticus the basal piece is about half of total length and median lobe shorter than the parameres.

Figures

FIGURE 6. Berosus parvus sp. n. (A–C) Habitus, A) dorsal view; B) lateral view; C) ventral view; D) Mesoventral process, ventral view, E) Abdomen, ventral view; (F–H) Aedeagus, F) dorsal view; G) lateral view; H) ventral view.

FIGURES 1–3. Habitat and type locality of the Berosus new species: 1) Brazil: Roraima State: Boa Vista County, pond near the RR-205 road, 2) detail of the habitat. 3) Type locality of Berosus andreazzei sp. n. (triangle), Berosus illuviosus sp. n. (square) and Berosus parvus sp. n. (circle).