Berosus degallieri, Queney, Pierre, 2010

Queney, Pierre, 2010, Two new species of Berosus Leach from Brazil (Coleoptera: Hydrophilidae: Berosini), Zootaxa 2506, pp. 51-58 : 52-55

Berosus degallieri sp. n.

( Figs. 1 , 3 , 4–6 )

Type material. Holotype (male): " Brazil: Brasilia,/ Distrito Federal, 1138 m,/ XI.1999,/ 15°45'35.99''S, 47°55'11.19''W,/ N. Dégallier leg." ( DZUP). Allotype (female): same data as holotype.

Diagnosis. Within the sticticus -complex, this species belongs to a group of taxa with well-defined black spots. Among this group it combines a blackened clypeus, metasternal process with posterior angle higher than postero-lateral angles, apical notch of the fifth ventrite with bifid tooth ( Fig. 6 ), extensive metafemoral pubescence, a long basal piece compared with total length of male genitalia ( Fig. 3 ), parameres and median lobe about the same length.

Description. Holotype (male). Total body length: 2.9 mm; maximal width: 1.4 mm (at metacoxae level); humeral width: 1.1 mm; maximal height: 1.05 mm (at metacoxae level); lenght/height: 2.76; length/maximal width-humeral width: 9.66.

Form and Color. General body form rather sturdy, oval, weakly convex, widened progressively from head up to the middle of elytra ( Fig. 1 ). Dorsal surface testaceous with extensive black areas without metallic sheen, rather shiny except on clypeus; black areas wide on labrum, in the form of a median and longitudinal band on clypeus, in the shape of a broad U on frons, shaded off on pronotal disc; black spots clearly defined on the basal third of the second elytral interstriae, on the first three interstriae behind the middle of the elytra, on humeral hump of interstria 6th and towards the middle of interstriae 8th, 9th and 10th; apical segment of maxillary palps, suture, scutellum, striae except 10th, elytral and pronotal punctures also blackened. Ground punctures on head and pronotum rather large and uniform-sized but irregularly spaced in some places, fairly dense (spaced by one up to four times their diameter). Ground punctures more superficial on clypeus. Micropunctures scarce.

Head. Eyes not very prominent, ocular index OI = 2.95 [OI = S/0.5(D-S) where D = width of head and S = minimal distance between eyes in dorsal aspect; OI was used by Stys (1960) for aquatic Heteroptera]. Antenna much longer than maxillary palpi.

Thorax. Pronotum with lateral angles rounded, posterior ones more widely. Scutellum punctate on its periphery. Elytra with ten fine striae, the first seven ones well impressed; punctures on striae spaced by 1 to 3 times their own width, set most close together along inner striae, and hardly larger than those on pronotum. Interstriae broad and flat, with punctures forming rather irregular rows, sometimes two or three in number, a little finer than those of striae. Micropunctures on interstriae, chiefly inner ones, rare and very light. Scutellar stria with eight punctures. Systematic punctures larger on interstriae 3rd, 5th and 7th. Sutural angle of each elytron narrowly rounded. No spine-like hairs on outer interstriae. Long hairs on interstriae 1st, 3rd, 5th and 11th. Ventral surface glossy, pubescent, mostly punctate, blackened except labium and prosternum testaceous. Mesosternal process laminar with a strong tooth pointing downwards, followed by a low and irregular ridge and ending in rounded angle ( Fig. 4 ). Metasternal process triangular and almost flat, with the postero-lateral angles not raised and produced into a rather strong obtuse angle ( Fig. 5 ). Posterior angle forming a narrow keel, broadly rounded in lateral aspect and strongly raised above the postero-lateral angles. Legs testaceous except pubescent and blackish part of femora. Femoral pubescence (male) covering nearly 80% of the hind and 70% of the middle femora. Male protarsi with expanded pads on the two basal segments; all protarsal segments, including the apical one, weakly swollen.

Abdomen. Lateral edges of ventrites smooth, the first ventrite without lateral depressions and with a median carina gradually depressed towards the posterior edge. Apical notch of fifth ventrite rather broad with its lateral edges converging backwards and its bottom strongly bidentate ( Fig. 6 ). Male genitalia ( Fig. 3 ) subcylindrical and rather thick, ventral face straight and dorsal face strongly convex in lateral aspect ( Fig. 3 a), distal part beyond basal piece very narrow in dorsal and ventral aspect ( Fig. 3 b,c). Total length: 0.78 mm, basal piece representing three-quarters of it. Parameres very strongly bent in their terminal part, with apex curved towards ventral face ( Fig. 3 a). Median lobe almost as long as parameres. Part of parameres beyond the basal piece dilated towards ventral face.

Variation. Allotype: total length: 3.3 mm; maximal width: 1.4 mm; humeral width: 1.1 mm; maximal height: 1 mm; length/height: 3.3; length/maximal width-humeral width: 11. General female body form more elongated and depressed than for the male. Protarsi without expanded pads and not swollen; apical segment one third thinner than in male.

Discussion. As shown in Table 1, three species combine a blackened clypeus, a metasternal process with a posterior angle higher than the postero-lateral angles, and an apical notch of the fifth ventrite with a bifid tooth: B. degallieri sp. n., B. guyanensis Queney, 2006 and B. nigrinus Knisch, 1921 but the last one is the only one to have its dorsal face entirely blackened. The first two species can be separated by their metasternal process with the postero-angles, nearly acute and very strongly produced in B. guyanensis , hardly produced in B. degallieri ( Fig. 5 ). Males are easily differentiated by examination of the genitalia: the distal pieces are spindle-shaped in ventral aspect in B. guyanensis , but flat and parallel in B. degallieri ; the parameres and median lobe are about the same length in B. degallieri ( Fig. 3 ), but much longer than the median lobe in B. guyanensis .

Etymology. Named for Nicolas Dégallier, an eminent French entomologist and specialist on the Histeridae , who collected the two types of the new species described here.

Distribution. This species is only known from Brasilia ( Brazil) where it was collected at a light-trap in "Cerrado".

Figures

FIGURE 3. Male genitalia of Berosus degallieri (0.78 mm long), a) lateral aspect; b) dorsal aspect; c) ventral aspect.

FIGURES 1 – 2. Dorsal habitus: 1) Berosus degallieri (3.3 mm long); 2) Berosus spiniger (6.6 mm long).

FIGURE 4 – 6. Ventral details of Berosus degallieri. 4) Mesosternal process,; 5) Metasternal process; 6) Fifth ventrite.