Review of the Berosus Leach of Venezuela (Coleoptera, Hydrophilidae, Berosini) with description of fourteen new species

Abstract The species of the water scavenger beetle genus Berosus Leach occurring in Venezuela are reviewed. Thirty-six species are recorded, including fifteen new species, fourteen of which are described here as new: Berosus aragua sp. n., Berosus asymmetricus sp. n., Berosus capanaparo sp. n., Berosus castaneus sp. n., Berosus corozo sp. n., Berosus ebeninus sp. n., Berosus garciai sp. n., Berosus humeralis sp. n., Berosus jolyi sp. n., Berosus llanensis sp. n., Berosus megaphallus sp. n., Berosus ornaticollis sp. n., Berosus repertus sp. n., and Berosus tramidrum sp. n. The fifteenth new species, known from a single female, is left undescribed pending the collection of males. Twelve species are recorded from Venezuela for the first time: Berosus ambogynus Mouchamps, Berosus consobrinus Knisch, Berosus elegans Knisch, Berosus geayi d’Orchymont, Berosus ghanicus d’Orchymont, Berosus guyanensis Queney, Berosus holdhausi Knisch, Berosus marquardti Knisch, Berosus olivae Queney, Berosus reticulatus Knisch, Berosus wintersteineri Knisch, and Berosus zimmermanni Knisch.


Introduction
Berosus Leach, 1817, one of five genera that comprise the tribe Berosini, is the largest genus of Hydrophiloidea with 273 species distributed worldwide (Hansen 1999, Short andFikáček 2011). It is one of the most commonly collected groups of water scavenger beetles in the world as well as one of the most recognizable due to their typical "hunchbacked" appearance. All known species are aquatic, and generally good swimmers. They inhabit a range of "traditional" aquatic habitats, with most species occurring in lentic situations such as ponds and marshes. However, some species are known from other habitats such as stream margins and the slack waters of rivers. In the present work we describe the first species known in part from seepage-like habitats (B. asymmetricus sp. n.). The South American Berosus were comprehensively revised by , with a significant addition four years later . Since then, a handful of additional species have been described, usually one at a time as they became known (e.g. Oliva 1995Oliva , 1998Oliva , 2002Queney 2006). Up to now, 85 species were known to occur in continental South America, not counting species incertae sedis.
In the present work, we raise the total number of species known from Venezuela from 9 to 36, including the description of 14 new species. For comparison, that is twice the eighteen species that are known from all of North America.

materials and methods
More than 2400 specimens of Berosus from Venezuela were examined for this study. A large portion of this material was the result of recent survey efforts for aquatic insects in Venezuela. In addition to this newly collected material, we examined the large holdings of Berosus from the US National Museum of Natural History, and the two largest insect collections in Venezuela, the Universidad Central de Venezuela and the Universidad del Zulia. A few additional incidental collections were also examined. Oliva, 2002 http://species-id.net/wiki/Berosus_apure Fig. 1 Berosus apure Oliva, 2002: 98. Material examined (6): VENEZUELA: Guárico State: Corozo Pando (8 km N.), 17-18.vi.1984, blacklight, leg Distribution. Venezuela (Apure, Guárico).

Berosus aragua
Diagnosis. This species appears to be closely related to B. alternans Brullé, 1841 (Argentina), by the shape of the male genitalia and the metaventral process not produced at the posterolateral angles. Berosus aragua has a much longer row of hairs on the paramera and a slightly shorter basal piece. Additionally, this new species has more deeply impressed elytral striae; the mesoventral process has the posterior tooth rounded, the posterior angle of the metaventral process is not raised and the apical notch of the fifth ventrite is produced into a pair of acute teeth. In B. alternans, the elytral striae are reduced to rows of punctures in anterior half, the posterior angle of the mesoventral process is not rounded, the posterior angle of the metaventral process is carinate and the apical notch of the fifth ventrite is produced into a pair of rounded (not acute) projections.
Pronotal punctures dense and coarse, with punctures on disc about the same size as those on frons, on posterolateral areas polygonal. Pronotum between punctures very sparsely micropunctate, shining. Scutellum coarsely punctate, shining. Elytral striae well-impressed, with small round punctures about the same size as pronotal ones, not overflowing outwards except on striae 4-6, the intervals between punctures lower than interstriae. Interstriae flat, wide, three times or more as wide as striae, the fourth, fifth and sixth slightly step-shaped at disc due to overflowing strial punctures; tenth weakly convex on anterior half; eleventh flat, but raised with respect to spaces between strial punctures. Inner interstriae with punctures about half the size of the strial ones, 1-2 seriated; outer interstriae with much finer punctures. Surface of elytra smooth and shining in males, reticulate in females. Elytral apices simple; spine-like hairs absent.
Mesoventral process with large curved anterior tooth pointed downwards and backwards, behind this the ventral margin concave, describing a quarter of circle; posterior angle rounded, less prominent than anterior tooth. Metaventral process narrow; posterolateral angles not produced, posterior angle not raised. First ventrite carinate between metacoxae and a little behind them. No lateral depressions. Ventrites 2-4 without carinate or teeth. Fifth ventrite with a wide, shallow apical notch, which is set medially with two distinct sharp teeth. Margins of all abdominal ventrites smooth.
Maxillary palpi short, apical palpomere about twice as long as penultimate, slender, subcylindrical. Basal pubescence on basal half of mesofemora and three-fifths of metafemora, limit convex towards apex. Protarsus of male with adhesive soles on the two basal tarsomeres, the first of which is thickened, as long as the second and third combined; fourth tarsomere thickened, as long as the first and second taken together. Claws slender, weakly arched, toothed at base.
Male genitalia laterally compressed (Fig. 5D). Basal piece two-fifths of total length. Parameres long, narrow, gradually acuminate, weakly curved towards the sternal side. Row of hairs on the parameres long, taking up about half the total length. In sternal view the parameres parallel-sided taken together, gently rounded distally, not broadened, with apices turned inwards. Median lobe shorter than parameres, subcylindrical, slender, straight.
Variation. This species exhibits a wider range of color variation than typical for most other Venezuelan Berosus, ranging from very pale to very dark, although some of the more darkened specimens appear to be so due to specimen preservation. Most material from Falcón State, the dorsal coloration is very pale, with some specimens entirely lacking pronotal maculae.
Regardless, the apical abdominal and aedeagal morphology are identical in these various color morphs. Etymology. The name refers to the Venezuelan region of Aragua, one of the states where this species was found.
Remarks. This species has been taken along the densely vegetated margins of ponds, in the gravel sidepools of rivers, and at lights. Diagnosis. The males of this species resemble B. festivus Berg in the thin carina in front of the apical notch. They differ in the unique asymmetrical genitalia and in the coarsely serrate edge of the mesoventral process.

Berosus asymmetricus
Description. Body length 2.1-2.6 mm; (holotype: total length: 2.3 mm; humeral width: 1.0 mm). Shape depressed. Head testaceous with a melanic triangle taking up a small part of the clypeus and the greater part of the frons. Pronotum testaceous with a strongly melanic band on the anterior margin behind the head; a pair of elongate paramedial discal spots; a less deeply melanic posterior band taking up one-third of the pronotum excepting the lateral margins. Scutellum dark. Elytra testaceous with small dark spots. Venter of thorax and abdomen dark brown in typical series. Maxillary palpi with distal palpomere darkened on apex. Femora with pubescent portion darkened, glabrous portion testaceous.
Punctures on clypeus fine and regular, coarser on frons, irregularly spaced, polygonal rather than round, rather sparse except along inner margin of the eyes, where they are contiguous. Pronotum with moderate-sized punctures (about twice the size of ommatidia), elliptical, with irregular spaces 1-4 times their diameter, which are shining, not micropunctate. Scutellum shining, with a few punctures similar in size to those on the pronotum. Elytral striae with round punctures, twice as large as those on the pronotum, contiguous, on the basal stria spaced by a whole diameter or a little more.
Interstriae flat on elytral disc, not step-shaped, 1.5-2 times as wide as striae, sparsely and finely punctate (punctures smaller than those on pronotum); between punctures shining, not micropunctate. Interstriae 10 convex, overhanging the eleventh between humeral humps and stridulatory patch. Eleventh interstria flat, about 1.5 times as wide as the tenth. Spine-like hairs absent.
Mesoventral process with curved anterior tooth directed downwards and backwards; behind this, the ventral margin concave and irregularly serrate, in some specimens forming a small, acute second tooth; posterior angle weakly raised. Metaventral process rather wide, posterolateral angles raised into rounded lamellae, posterior angle carinate, not raised. First ventrite with carina thick between metacoxae, behind thin, reaching the posterior margin of the ventrite. Lateral depressions absent. Fifth ventrite with shallow apical notch, the bottom of the latter with two contiguous rounded teeth, in front of these a thin carina.
Maxillary palpi short and thick in both sexes, darkened at apex of fourth palpomere. Basal pubescence on half of mesofemora and three-fifths of metafemora, limit transverse. Protarsus of male short and thick, with basal tarsomere about 1.5 times as long as second, both weakly thickened, bearing small soles of adhesive hairs. Claws weakly arched.
Male genitalia (Fig. 7A): basal piece four-fifths of total length, three times as long as wide. Parameres with basal two-thirds encased in apical half of basal piece, asymmetrical. In lateral aspect, the unencased part of the parameres evenly curved towards the sternal side, describing nearly a quarter of a circle; apices narrowed. Row of hairs rather long. In tergal aspect, parameres strongly and regularly curved inwards. Median lobe longer than parameres, but strongly curved towards one side, subcylindrical, acuminate at the apex which is directed to one side.
Remarks. This species, remarkable for its unusual genitalia, is apparently restricted to granite outcrops. All specimens have been collected in rock pools and small streams that occur on the bare rock of the numerous outcrops along the northwestern margin of the Guiana Shield region of Venezuela (Fig. 27). Several longer series have been collected in small seasonal streams that form on the outcrops which drain water during the wet season, as well as in small rock pools adjacent to the streams.  Calabozo, 9-13.ii.1969  Diagnosis. Large species without metallic luster on dorsum. Abdomen black. Elytral apices bispinous, sutural angle not produced. Mesoventral process with curved anterior tooth, posterior angle strongly raised. First ventrite with lateral depressions: fifth with smooth margins, with apical notch produced at bottom into a pair of contiguous rounded teeth. Basal tarsomere of males about twice as long as second. Male genitalia compressed, parameres long, narrow, with short subapical row of hairs (Fig. 8).

Berosus brevibasis
Description. Body length 5.0-6.7 mm (holotype: total length: 5.6 mm; humeral width: 2.2 mm). Shape elongate, humeral humps weakly prominent. Labrum and clypeus testaceous, frons melanic at base, in some specimens entirely black except on the angles between each eye and the frontoclypeal suture. Pronotum testaceous with a narrow central melanic spot divided by a testaceous median line. Scutellum diffusely melanic. Elytra testaceous with melanic spots. Venter of thorax reddish in typical series. Abdomen black. Maxillary palpi with fourth palpomere darkened on apical onefourth. Femora with pubescent portion darkened, glabrous portion testaceous. Punctures on clypeus moderately dense, about the same size as ommatidia; on frons coarser and denser; micropunctation between punctures; frontal carina well-marked. Pronotal punctures about twice the size of an ommatidion, on disc spaced by 2-4 times their diameters, on sides contiguous. Elytra micropunctate between punctures, shining. Scutellum reticulate, with a few punctures. Elytral striae fine and well-incised, bearing punctures about the same size as the pronotal ones. Interstriae wide, flat, even the external ones, bearing punctures as coarse as the serial ones, 2-3 seriated. Elytral apices emarginate almost in a semicircle, with sutural angle not produced, parasutural tooth triangular, sharp. Spine-like hairs on all the interstriae on posterior third of elytra.
Mesoventral process laminar, with large, curved anterior tooth directed downwards and backwards, behind this the ventral margin straight, posterior angle strongly raised but much less so than anterior tooth. Metaventral process narrow, posterolateral angles produced into small triangular laminae; posterior angle not raised. First ventrite carinate only between metacoxae, with lateral depressions. Fifth ventrite with small apical notch raised at the sides, the bottom bearing a blunt bifid tooth (Fig. 8A). Maxillary palpi long, with fourth palpomere ensiform, longer than third; second palpomere as long as third and fourth together. Basal pubescence on three-fifths of meso-and metafemora, limit transverse. Protarsus of male with small adhesive soles on the two basal tarsomeres, which are weakly thickened, the basal one about twice as long as the following one. Claws slender, toothed at base.   Male genitalia (Fig. 8B) compressed: basal piece one-third of total length. Parameres long, narrow, weakly sinuate, with apices turned towards the sternal side, rounded; rows of hairs rather short, subapical. Median lobe shorter than parameres, subcylindrical, moderately thick, regular in thickness, weakly curved.
Etymology. The name refers to the river Capanaparo, near which the new species was found.

Remarks.
Both collecting events for this species were at the same unusual locality: a marsh and pools formed around a dune complex (the Médanos de la Soledad) in the middle of the Llanos region (  Diagnosis. This species appears close to B. sinigus Oliva, 1989 (Argentina, Brazil) and B. hispidulus Oliva, 1993 (Brazil), in the general shape of the genitalia and the color pattern. It differs from both in having spine-like hairs on the outer interstria only ant in the characters of the male genitalia, noticeably the very long basal piece (Fig. 9).
Description. Body length 4.3 mm (holotype: total length: 4.3 mm; humeral width: 1.8 mm). Shape depressed. Labrum testaceous; clypeus testaceous with a very small dark median triangle medially, frons testaceous in lateral quarters, with central half darkened. Pronotum testaceous with a median melanic parallel sided stripe divided into two lateral halves by a thin testaceous median line. Scutellum dark brown. Elytra testaceous with dark spots in the usual pattern. Venter of thorax and abdomen very dark brown. Maxillary palpi yellow with apical segment darkened at apex. Femora with pubescent portion darkened, glabrous portion testaceous.
Clypeus with fine punctures (rather smaller than ommatidia), distance between punctures 1-2 times their diameter. Frons with punctures subequal in size to an ommatidion, distance between punctures 2-3 times their diameter. Maxillary palpi slender, not elongate. Pronotal disc with fine round punctures spaced by 2-4 times their diameter; surface shining, not microreticulate. Scutellum with dense punctures the same size as those on pronotum, surface shining. Elytral striae fine, on disc bearing punctures spaced by 1-2 times their diameter; outer striae more densely punctuated. Outer stria obsolete on apical fifth. Interstriae flat, with uniseriated punctures about the same size as those on striae, outer ones with obsolete punctures, on striae 9 and 11 a few larger punctures. Elytral apices separately rounded; with spine-like hairs on interstria 11 only.
Mesoventral process with small, straight anterior tooth directed posteroventrally, behind ventral margin weakly convex, then gradually depressed to posterior end which is not raised. Metaventral process narrow, finely carinate on front of medial depression, posterolateral angles produced into triangular laminae, posterior angle not raised. First ventrite carinate only between metacoxae, and without lateral depressions. Fifth ventrite with shallow apical notch, which is set with two triangular teeth. Meso-and metafemora with pubescence on basal two-thirds, the limit transverse, convex. Protarsus of male weakly thickened at base, with basal two tarsomeres expanded and with ventral pads, first tarsomere about twice as long as second. Claws weakly curved.
Male genitalia with basal piece extending three-quarters of total length. Parameres acuminate, unencased portion divided into a sternal membranous part, which has a weakly convex sternal margin, and a more strongly sclerotized tergal part, narrow, acuminate, straight.
Row of hairs rather short, extending along subapical third. Median lobe a little shorter than parameres, straight, acuminate at the apex.
Etymology. The name alludes to the brown coloring of the dorsum, from the Latin nux castanea, "chestnut", given adjectival form.

Berosus consobrinus
Remarks. This species was collected at two localities in the Gran Sabana, as well as a series from the central Llanos region. Diagnosis. Moderate-sized species of the Berosus holdhausi complex, without metallic luster on dorsum, resembling B. marquardti Knisch, but without reddish hue on dorsum, with mesoventral process laminar, anterior tooth of this process straight, carina on first ventrite straight in lateral aspect and with median lobe of male genitalia subapically angular, apically narrow. This species is remarkable by the convex, short, broad body shape and the very coarse dorsal sculpture (Fig. 14A).

Berosus corozo
Description. Body length: 3.6-4.3 mm. (holotype: total length: 4.3 mm; humeral width: 1.55 mm). Shape convex. Dorsum entirely testaceous, yellow in the type specimens, with base of frons, paramedial bands on pronotal disc and scutellum slightly darker. Elytra with small, weak darker spots on elytral disc and apical portion; the usual humeral and lateral spots are absent.
Mesoventral process in the shape of a short, strongly raised lamina with two teeth of equal height divided by a shallow semicircular notch; anterior tooth straight, directed posteriorly. Metaventral process short, wide, with posterolateral angles rounded and produced. First abdominal ventrite with thick, high carina along its entire length medially, straight in lateral aspect. Fifth ventrite strongly raised at the sides of small apical notch, which is medially set with two contiguous, diverging teeth. Lateral margins of abdominal ventrites finely crenulate. Meso-and metaventer with pubescence on basal two-thirds, distal limit briefly oblique. Protarsus of male with two basal tarsomeres bearing stiff hairs which are not expanded to form a pad.
Male genitalia ( Fig. 15C) with basal piece about twice as long as wide, half of total length. Parameres strongly narrowed in apical third, apices weakly directed towards sternal side; sternal margin bearing a short row of long hairs on the subapical concave part. Median lobe shorter than parameres; in lateral aspect strongly curved towards the tergal side, subapically swollen with angular projection followed by a deep semicircular notch, narrowed apex directed towards the sternal side; in tergal aspect the subapical swelling spindle-shaped, with a median groove.

Remarks.
Nothing is known about the biology of this species. Most specimens were collected at light. Diagnosis. This species keys to B. consobrinus Knisch, 1921 or B. megillus d'Orchymont in the key by . The new species differs from the latter in having much finer punctation and the sides of the ventrites crenulate. From B. consobrinus it differs by the male genitalia and the extended melanization of the dorsum.

Berosus ebeninus
Description. Body length: 3.6-3.9 mm. (holotype: total length: 3.9 mm; humeral width: 1.6 mm), Shape in dorsal aspect short and wide. Labrum, clypeus and frons dark brown to black with weak metallic sheen. Pronotum black in typical series, with metallic sheen, testaceous on lateral margins and, more extendedly, on anterior angles. Scutellum melanic. Elytra melanic, in the typical series deep black, shading into dark reddish brown at the sides and apices. Venter of thorax and abdomen dark reddish brown to nearly black. Maxillary palpi pale yellow with fourth palpomere darkened apically. Femora with pubescent and glabrous regions black and testaceous respectively. The remainder of the legs testaceous.
Punctures on clypeus about twice as large as ommatidia, contiguous, polygonal. Punctures on frons 3-4 times the size of an ommatidium, contiguous, polygonal, larger at the base of frons where there is a narrow median unpunctured line, not carinate. Pronotum with coarse (4-6 times an ommatidion), irregularly spaced (spaces equivalent to 1-2 diameters) punctures; surface coarsely micropunctate (micropunctures nearly as large as ommatidia). Lateral margins of pronotum serrate. Scutellum bearing a few punctures, rather smaller than those on pronotal disc. Elytral striae bearing punctures about the same size as those on pronotum, contiguous. Interstriae convex, narrower than striae, bearing punctures subequal in size as an ommatidium. Interstria 11 costate on anterior three-fourths, overhanging the elytral margin, not costate below humeral hump; the latter dentate. Elytral apices rounded; spine-like hairs absent. Mesoventral process laminar, with anterior tooth weakly curved, directed posteroventrally, behind this the free ventral margin concave, posterior angle weakly raised. Metaventral process wide, carinate before median depression, with posterolateral angles produced into rounded laminae, posterior angle finely carinate, not raised. Meso-and metafemora with pubescence on basal three-fifths and three-fourths respectively, its limit transversely oblique. Protarsus of male only slightly enlarged, the two basal tarsomeres slightly expanded and with a setal pad, which can hardly be said to form a sole. Claws weakly arched, dentate at base.
First ventrite medially carinate on most of its length, with carina faint to nearly absent at posterior margin. Fifth ventrite with small apical notch, set with two acute teeth medially. Margins of abdominal ventrites finely crenulate. Aedeagus (Fig. 15A) with basal piece about twice as long as wide, half of total length. Parameres gradually acuminate, curved, apices simply acuminate, directed towards the sternal side; row of hairs short, subapical. Median lobe longer than parameres, thick, weakly curved, abruptly swollen subapically, narrowed acuminate apex directed sternally.
Etymology. The name derives from the Latin word ebenus -i, meaning "ebony", and it alludes to the blackish dorsal coloring of this species.

Remarks.
It is interesting to note that while many hundreds of specimens were collected at one locality in the central Llanos region (most at lights), not one specimen was found from recent collecting efforts.   Diagnosis. Within the sticticus-complex (small species without dorsal metallic luster), this species is remarkable by the strongly melanic labrum and by the absence of the pair of spots usually present on the elytral disc on the fourth interstria. It may be distinguished from the other new species with a similar coloring by the tenth elytral interstria wider than the eleventh, the weak anterior tooth of the mesoventral process, directed downwards and backwards, and by the apical notch in the fifth apparent ventrite, which bears a pair of teeth at bottom.
Clypeus convex in lateral aspect, sparsely and finely punctured. Frons with somewhat coarser punctures; frontal carina apparent; base of frons weakly reticulate. Pronotum very short and wide, about three times as wide as long; punctures round to polygonal, on disc about twice the size of an ommatidion, at the sides coarser, contiguous. Background micropunctate, shining. Scutellum with a few coarse punctures; ground rugulose, shining. Elytral striae fine with deeply impressed punctures about the size of those on pronotum. Interstriae moderately wide, flat except for the ninth, tenth and eleventh which are very weakly convex, step-shaped, bearing punctures much smaller than the serial ones; ground micropunctate. Elytral apices simple. No spine-like hairs.
Mesoventral process with large, weakly curved anterior tooth that points downwards and backwards; behind this the ventral margin finely serrate; posterior angle weakly raised. Metaventral process narrow; posterolateral angles produced into small rounded lamellae; posterior angle carinate, in lateral aspect convex, not more strongly raised than posterolateral ones. First ventrite carinate in anterior two-thirds, the carina thick at base, gradually narrowing backwards. No lateral depressions. Fifth ventrite with shallow apical notch; bottom of the later produced into a wide-based tooth.
Maxillary palpi short; second segment shorter than fourth, which is ensiform but very thick. Basal pubescence on two-thirds of mesofemora and three-fourths of metafemora, limit transverse. Protarsus of male with small adhesive soles on the two basal segments, which are weakly thickened; basal segment hardly longer than the following one; distal segment as long as the other three together. Claws slender, weakly arched, toothed at base.
Male genitalia: basal piece three-quarters of total length. Parameres curved towards the sternal side; apices narrow; short subapical row of hairs; sternal margin straight. Median lobe as long as parameres, nearly straight, with weakly swollen spindle-shaped apex.
Etymology. This species is dedicated to Mauricio García, who has been an ardent student of aquatic Coleoptera of Venezuela for the last fifteen years, and friend and colleague of the authors.
Remarks. This species is known from pools and streams along the northwestern margin of the Guiana Shield (Fig. 29). In a few instances during the dry season, when habitats are becoming scarce, the species was collected by the thousands in rock pools along the Orinoco River. Remarks. This species is thus far known only from a few closely-situated localities near the Caribbean coast of Falcón State where it was found in ponds and a roadside ditch. Oliva (2007) records this species from northern Brazil, French Guiana and Paraguay (Central), always in small numbers, and suggests that this species might have a widespread South American distribution, like B. patruelis Berg. The findings from Venezuela suggest this is species associated with the Orinoco basin and the coastal plains between the latter and the mouth of the Amazonas, and that Paraguay may be the southern limit of its distribution  Oliva (1989: 158).  Berosus holdhausi Knisch, 1921: 12. Berosus holdhausi Knisch: Oliva (1989   Diagnosis. Moderate-sized, broad-shaped, not very convex species with strong metallic luster on dorsum of head and often with weak metallic sheen on medial spot on pronotum. Elytra with small, well-defined black spots, including an additional pair below the humeral humps (Fig. 16A). Mesoventral process entirely laminar. First ventrite carinate in anterior half. Male genitalia as in Fig. 17A. The extended subhumeral spots distinguish B. humeralis from the closely related B. ornaticollis sp. n., besides the other characters listed in the key. There are hardly any species that may be confused with these two.
Description. Body length: 3.7-4.0 mm. Shape short and broad, with prominent humeral humps, but rather depressed. Eyes moderately prominent in both sexes. Labrum melanic at base, testaceous on the distal margin. Dorsum of head melanic with strong metallic luster. Pronotum testaceous with a median melanic spot covering approximately two-fifths of total pronotal width, without testaceous median line, in most specimens with metallic sheen. Scutellum melanic. Elytra testaceous with small melanic spots as in B. ornaticollis sp. n., but the additional subhumeral spots more extensive, taking up the interstriae 8 and 9 and about half  Head densely punctured, punctures on clypeus about the size of an ommatidion, on frons slightly larger. Pronotal punctures slightly larger than ones on head, round, moderately dense, spaced by the equivalent of 2-4 times their diameter; surface sparsely  and finely micropunctate, shining. Scutellum with a few deeply impressed punctures, smaller than pronotal ones; surface shining. Elytral striae fine on disc, the external ones a little more shallow, with dense punctures about the same size as the pronotal ones, not overflowing except on a short stretch of striae 6-8 on the posterior half of the elytra. Interstriae wide, flat, bearing punctures smaller than those on striae, irregularly uniseriated; outer interstriae slightly convex; background smooth. Elytral apices simple, slightly more pointed and outwardly deflexed in females; spine-like hairs absent.
Mesoventral process small, laminar, with curved anterior tooth pointing downwards, a little thickened; posterior tooth raised but less prominent than anterior one. Metaventral process as in B. ornaticollis. First ventrite carinate medially in the anterior half, carina broadened and lowered behind metacoxae; without lateral depressions. Ventrites 2-4 not carinate. Fifth ventrite with shallow apical notch, set with two straight, sharp teeth.
Maxillary palpi short, thick. Meso-and metafemora with pubescence on basal half and three-fifths respectively, limit oblique. Protarsus of male with basal tarsomeres strongly enlarged, with adhesive sole; second without sole. Claws fine, toothed.
Male genitalia (Fig. 17A): basal piece about two-fifths of total length. Parameres narrow, rounded at apex, in tergal aspect elbowed and curved inwards. Row of hairs rather long. Median lobe a little shorter than parameres, complex.
Etymology. The name refers to the characteristic subhumeral spots, taking up part of the striae 8-10.
Distribution. Venezuela (Amazonas, Bolívar). Remarks. This species is known only from granite outcrops in along the northwestern fringe of the Guiana Shield. It has only been found in distinctive "rock pools" that collect rainwater or in small streamlets that drain such pools (Fig. 27). Diagnosis. Within the sticticus-complex (small species without metallic luster on dorsum), this species is remarkable by the deeply melanic labrum and the absence of the pair of elytral spots on the fourth interstriae. It may be distinguished from B. garciai sp. n., which has a similar coloring, by the tenth elytral interstria not wider than the eleventh, the strong anterior tooth of the mesoventral process, directed downwards, and by the apical notch in the fifth apparent ventrite, which bears a single tooth at bottom. The parameres of B. jolyi (Fig. 18) are more strongly curved in lateral aspect than those of B. garciai (Fig. 7B).

Berosus jolyi
Description. Body length: 2.3-3.1. Shape depressed. Labrum deeply melanic; clypeus testaceous; frons testaceous darkened at base. Maxillary palpi melanic on apical one-third of apical palpomere. Head and pronotum reddish in typical series; elytra testaceous with small reddish spots, the pair of spots on interstriae fourth absent. Venter blackish. Femora testaceous in typical series. Eyes of males not prominent. Head and pronotum with moderately coarse punctures, on pronotal disc elliptical and coarser (more than twice the size of an ommatidion). Ground sparsely but deeply micropunctate. Lateral margins of pronotum entire. Elytral striae coarsely and deeply punctate, the spaces between punctures sunken with respect to interstria, so that the striae are distinctly groove-like; punctures on outer striae subquadrate. Inner interstriae about 3 times as wide as striae, flat, sparsely and finely, but deeply punctate. Outer interstriae about the same width as striae, eleventh weakly convex on middle one-third of length, elsewhere flat. Elytral apices narrowly rounded. Mesoventral process laminar; anterior tooth acute, directed downwards; posterior angle broadly rounded, as strongly raised as the anterior tooth; in between a deep semicircular notch. Metaventral process small, weakly raised, with posterolateral angles barely produced. First ventrite with a fine carina which reaches the posterior margin; fifth with a shallow apical notch bearing a single tooth at bottom; lateral margins smooth. Femoral pubescence briefly oblique, covering about two-fifths of mesofemora and half of metafemora. Protarsi of males with soles on the two basal tarsomeres, which are a little thickened.
Male genitalia: Basal piece long, more than 3 times as long as wide, taking up about three-quarters of total length. Parameres encased in basal piece for most of their length; unencased portion strongly and regularly curved towards the sternal side, bearing a short subapical row of hairs. Median lobe a little longer than parameres, subcylindrical, with apex swollen, spindle-shaped.
Etymology. This species is dedicated to Dr. Luis Jose Joly T., Curator of Coleoptera at MIZA.

Distribution. Venezuela (Anzoátegui).
Remarks. This species has been collected in standing waters. Diagnosis. This species is one of the few that have the posterior angle of the metaventral process raised into a rounded lamella higher than the posterolateral angles. This character is also found in B. nigrinus Knisch, 1921 (Brazil: Mato Grosso), B. sticticus Boheman, 1859 (Brazil: Mato Grosso, Rio de Janeiro) and B. guyanensis Queney, 2006 (French Guiana, Venezuela: Bolívar). The basal piece is longer than in B. sticticus and shorter than in B. guyanensis.  Description. Body length: 2.3-2.6. Shape depressed. Eyes not prominent. Labrum weakly melanic. Clypeus testaceous with small dark triangle on the middle of the posterior margin, frons testaceous with melanic median area. Pronotum testaceous with small discal melanic spot. Scutellum weakly darkened. Elytra with small melanic spots, the pair on the fourth interstria absent in observed material. Venter weakly melanic. Maxillary palpi with apical palpomere darkened on apex. Femora with pubescent portion darkened, glabrous portion testaceous.

Berosus llanensis
Punctures on clypeus round, sparse, on frons a little coarser, about twice the size of ommatidia. Pronotal punctures elliptical, moderately dense. Ground distinctly micropunctate, shining. Scutellum densely punctate. Elytral striae fine on disc, bearing punctures about the same size as those on pronotum; outer striae shallow. Interstriae flat, even the outer ones; odd-numbered ones with distinct punctures, even-shaped ones with fine or obsolete punctures. Lateral margin of elytra with a row of round punctures spaced by about twice their diameter. Elytral apices separately rounded. Spine-like hairs absent.
Mesoventral process with a large straight anterior tooth, directed downwards. Metaventral process small, with posterolateral angles produced into small triangular laminae, posterior angle raised into a rounded lamina, in lateral aspect convex, scarcely higher than posterolateral angles. First ventrite carinate, without lateral depressions. Fifth ventrite with apical notch shallow, bottom of notch weakly produced; the males bear in front of the notch two raised, sharp teeth, one behind the other.
Maxillary palpi short, thick. Basal pubescence on two-thirds of mesofemora and three-quarters of metafemora, limit transverse-oblique. Protarsus of male short, sturdy, with fourth tarsomere as long as the first three together; first tarsomere about one and a half times as long as the second, both weakly swollen. Claws weakly arched.
Male genitalia: basal piece about twice as long as wide, two-thirds of total length. Parameres curved towards sternal side, with narrowed apices, bearing a short subapical row of hairs. Sternal margin strongly convex. Median lobe a little shorter than parameres, moderately thick, curved, apex blunt.
Etymology. The name alludes to the fact that this species is found on the vast plains region of central Venezuela, Los Llanos.
Description. Body length: 6.0-7.7 mm. Shape elongate, depressed, not very narrow. Eyes prominent, a little more in males. Maxillary palpi slender, rather long, a little more so in males because the apical segment is longer and more slender than in females. Dorsum of head, pronotum, scutellum, and elytra testaceous, except slightly darkened on base of frons, a pair of narrow paramedial bands on pronotal disc, and small elytral spots in the usual pattern. Venter of thorax and abdomen dark brown; maxillary palpi darkened at tip of apical segment; femora with pubescent portion darkened, glabrous portion testaceous.
Dorsal sculpture moderate to fine, regular; punctures round, only on the base of frons a little elliptical. Head and pronotum with punctures about twice the size of an ommatidion; micropunctures about one-sixth the size of punctures. Elytral striae deep, well-im-pressed, finely punctured. Interstriae flat, wide, with moderate-sized punctures disposed in several series, on posterior half of elytra a little coarser and bearing spine-like hairs. Elytral micropunctures fine, on posterior half obsolete. Elytral apices emarginate, with acute parasutural spine; in males sutural angle broadly rounded, comprising the three inner striae; in females the emargination a little broader and the sutural angle produced into a short straight spine. Mesoventral process laminar, with large, curved, but not acute, anterior tooth, behind the margin obliquely lowered. Metaventral process narrow, with small median depression; posterolateral angles produced into triangular laminae, posterior angle not raised. First ventrite carinate medially only between metacoxae, with deep, moderately large lateral depressions. Fifth ventrite with shallow apical notch in females, in males raised into a disc around a narrow, very deep notch (Fig. 21B). Lateral margins of abdominal ventrites smooth. Meso-and metafemora with pubescence on basal threefifths and three-quarters respectively. Male protarsi with the two basal tarsomeres thickened, bearing adhesive soles; first about twice as long as second, fourth slender, longer than 3 basal segments taken together. All claws long, slender, very weakly curved.
Male genitalia: Basal piece about two-fifths of total length. Parameres complex, in lateral aspect with wide blunt apices, with membranous appendices in a ventral position. Median lobe much shorter than parameres, a little shorter than the appendices (Fig. 21B). Etymology. Named after the comparatively large aedeagus. Distribution. Guyana and Venezuela (Apure, Bolívar, Delta Amacuro, Monagas). Remarks. All known collecting events for B. megaphallus represent standing waters, both permanent and temporary.  probably handled this species (from Venezuela [Barinas] and Nicaragua [Zelaya]), but believed at the time that there was a gradient in the size of male genitalia of B. truncatipennis Castelnau, "with shorter, thicker organs in specimens of the Antilles area and Orinoco basin, and longer, more slender organs in those of the middle and lower Paraná." Diagnosis. Moderate-sized, broad-shaped, not very convex species with strong metallic luster on dorsum of head and often with weak metallic sheen on medial spot on pronotum. Elytra with small, well-defined black spots, including an additional pair below the humeral humps (Fig. 16B). Mesoventral process entirely laminar. First ventrite carinate in anterior half. Male genitalia as in Fig. 17B. The melanic spots below the humeral humps are most distinctive; they are shared with B. humeralis sp. n., but they are less extended, taking up only a part of the ninth interstria. This species belongs to the auriceps-complex. The shape of the median lobe is most characteristic; in B. auriceps the median lobe is narrowly rounded at the apex; in B. aulus d'Orchymont, 1941 the moderately thick median lobe is much shorter than the parameres, and in B. ethmonotus  the apices of the parameres are broader and directed outwards. The new species may be distinguished from all the others by the toothed claws.

Berosus olivae
Description. Body length 3.4-4.6 mm. Shape short and wide, moderately convex. Eyes moderately prominent in both sexes. Labrum black, dorsum of head melanic with strong metallic luster. Pronotum with remarkably large central melanic spot, without a testaceous median line, in most specimens with a metallic sheen; sides of the pronotum testaceous. Scutellum black. Elytra testaceous with small melanic spot in the normal generic pattern, save for a pair of additional spots which delimit the humeral humps on their ventral side and extend over a short stretch of the ninth interstria. Venter of thorax and abdomen melanic. Maxillary palpi darkened on apical one-third of distal segment. Femora with pubescent portion darkened, glabrous portion testaceous.
Head coarsely and densely punctured, punctures on frons about twice the size of ommatidia. Pronotal punctures larger than the ones on head, round, dense, irregular in spacing. Ground sparsely and finely micropunctate, shining. Scutellum with a few deeply impressed punctures, smaller than pronotal ones; ground alutaceous. Elytral striae shallow, not distinctly impressed, with coarse punctures about the same size as pronotal ones, overflowing outwards. Interstriae wide, flattened, bearing punctures smaller than those on striae, 1-2 seriated; outer interstriae slightly convex; background smooth in males, reticulate in females. Elytral apices simple. Spine-like hairs absent.
Mesoventral process small, laminar, with curved anterior tooth pointing downwards, a little thickened; posterior tooth raised but less prominent than anterior one. Metaventral process wide, flat. First ventrite carinate in anterior half, without lateral depressions. Ventrites second to fourth not carinate. Fifth ventrite with shallow apical notch, the bottom of the latter bearing two short rounded teeth.
Maxillary palpi short, with second palpomere short and thick. Basal pubescence of mesofemora and of metafemora slightly oblique, extending to a little less than half of the femoral length on anterior margin, and a little more than half on the posterior margin. Protarsus of male with basal tarsomere weakly thickened, bearing adhesive sole, about twice as long as the second tarsomere that does not bear a sole. Claws weakly arched, angular at base, bearing a small sub-basal tooth.
Male genitalia (Fig. 17C): basal piece two-fifths of total length. Parameres acuminate, in lateral aspect almost sickle-shaped, in tergal aspect weakly and regularly curved inwards. Apices broadly rounded; short subapical row of hairs. Median lobe a little shorter than the parameres, cylindrical and rather slender in basal three-fifths, very thick and subconical in apical two-fifths, with a sternal ridge.
Etymology. The name alludes to the deeply sculptured, shining, brightly colored pronotum of this species.
Distribution. Venezuela (Amazonas, Bolívar). Remarks. As with B. humeralis sp. n., this taxon is known only from granite outcrops in along the northwestern fringe of the Guiana Shield. It has only been found in distinctive "rock pools" that collect rainwater or in small streamlets that drain such pools. The allied B. auriceps and B. aulus are found in marginal pools of streams with rocky to sandy substrates .

Remarks.
Originally described from Argentina, it was recorded from Venezuela (Barinas: Santa Barbara) by .
Punctures on clypeus about the size of ommatidia, on frons about twice that size, on the base of frons a little larger, contiguous, rather polygonal than round; surface between punctures micropunctate. Pronotal punctures elliptical, moderately coarse, about twice the size of an ommatidion, spaces equivalent to 1-3 diameters, irregular; on the sides punctures round, finer and spaced by 2-3 times their diameter; between punctures there are numerous micropunctations a little smaller than an ommatidion. Scutellum shining, bearing a few punctures. Elytral striae shallow on disc, bearing punctures smaller than those on the pronotum; striae eight, ninth and tenth reduced to rows of punctures on anterior one-third. Interstriae flat, on disc densely micropunctate and bearing punctures about the same size as those on striae; on outer interstriae punctures obsolete. Elytral apices weakly produced in line with the second interstria. Spine-like hairs on all striae (Fig. 22B).
Mesoventral process laminar, with large anterior tooth, very strongly and angularly curved, directed backwards; concave behind ventral margin; posterior angle rounded, strongly raised, but much less so that anterior tooth. Metaventral process narrow, finely carinate in front of median depression; posterolateral angles produced into rounded laminae, posterior angle not raised. First ventrite carinate only between metacoxae, with moderately large, rounded lateral depressions. Fifth ventrite with shallow apical notch, the bottom of which bears two triangular teeth. Lateral margins of abdominal ventrites smooth. Maxillary palpi elongate, slender; second palpomere longer than fourth, fourth longer than third. Basal pubescence on three-quarters of mesofemora and of metafemora, limit convex. Protarsus of male with first and second tarsomeres strongly thickened, with large adhesive soles, the first about twice as long as the second. Claws weakly arched, angular at base.
Male genitalia (Fig. 23D): basal piece three-fifths of total length, about two and a half times as long as wide. Parameres long, parallel-sided, broadly rounded at apices, with a rather short row of hairs which takes up about half of the unencased part of the parameres. Median lobe a little longer than as parameres, subcylindrical, rounded at apex, with long, fine, weakly raised tergal ridge and a rather small, but distinct sternal opening.
Etymology. From Latin reperio, "to find", alluding to the fact that this species was discovered only after dissecting out the male genitalia.
Distribution. Venezuela (Apure, Barinas, Guárico). Remarks. Most specimens were taken from standing waters. Diagnosis. This species keys to B. marquardti Knisch, 1921 in the key by . It differs by the genitalia, especially the median lobe, which in the new species is longer than the parameres and very strongly thickened at the apex (Fig. 15D), and also by the shape of the carina on the first apparent ventrite, which in the new species is much more strongly raised, very strongly convex on anterior two-thirds, behind lower but raised into a separate curve, and by the margins of the fifth ventrite, crenulate in B. marquardti, coarsely dentate in the new species (Fig. 15D). Otherwise the two species are much alike.

Berosus tramidrum
Description. Body length 3.3-3.9 mm. Shape short, broad, convex. Labrum, clypeus and small area of frons close to suture testaceous; most of frons melanic, in typical series reddish. No metallic luster. Pronotum testaceous with narrow median melanic spot divided by a median testaceous line. Scutellum melanic. Elytra testaceous with small spots following the usual pattern. Venter weakly melanic (light reddish in typical series). Femora with pubescent portion darkened, glabrous portion testaceous. Palpi with apical palpomere strongly melanic on distal one-fourth.
Clypeus with dense punctures about the size of one ommatidion, in lateral aspect convex, swollen. Frons even more densely punctured, the punctures twice the size of those on clypeus. Pronotum narrower than humeral humps, bearing contiguous puncture 2-3 times as large as ommatidia, round to polygonal in shape; between these a few deep micropunctures. Elytral striae with deep punctures, on elytral disc about twice as large as those on pronotum, on the sides larger and squarish. Interstriae narrower than striae, convex, the eleventh costate on most of the length, even at the elytral apex. Micropunctation fine but distinct. Humeral angle serrate. Elytral apices narrowly rounded. Spine-like hairs absent.
Mesoventral process short, strongly raised, with hood-like anterior tooth, strongly curved, directed downwards. Posterior angle raised, blunt, more weakly raised than anterior tooth. Metaventral process very wide, posterolateral angles produced into rounded laminae, posterior angle a little less strongly raised, in lateral aspect rounded. First ventrite carinate in its whole length, carina very strongly raised, convex, in anterior two-thirds of sternite further raised, therefore describing a double curve in lateral aspect. Fifth ventrite raised at each side of the deep, narrow apical notch, bidentate at bottom. Ventrites first to fourth crenulate at the sides, fifth coarsely serrate.
Maxillary palpi short, thick. Basal pubescence on two-thirds to three-quarters of mesofemora and two-thirds to three-fifths of metafemora, limit oblique. Protarsus of male almost linear, first and second tarsomeres with small tufts of adhesive hairs; first slightly longer than second. Claws slender, weakly arched, weakly toothed at base.
Male genitalia remarkably small, compressed: basal piece about twice as long as wide. Parameres broadly acuminate, apices strongly curved towards the sternal side. Row of hairs very long, extending along most of the part of the parameron not encased in the basal piece. Median lobe longer than the parameres, strongly curved towards the tergal side, with apex very abruptly and strongly thickened into a rounded club which protrudes entirely from the parameres.
Etymology. The name is an arbitrary association of letters, derived from an anagram of "marquardti".
Remarks. This species resembles B. marquardti Knisch, 1921 from which it may be distinguished by the remarkably high, very convex carina on the first apparent ventrite, which in lateral aspect describes a double curve, and by the male genitalia with the median lobe longer than the parameres. In B. marquardti, the carina is convex only on its middle portion and the median lobe is rather shorter than the parameres, with the apical swelling weaker.

Key to species of Venezuelan Berosus
Some species from neighbor countries have been added for comparison.

1
Dorsal sculpture very coarse (Figs 10, 14). Punctures on pronotum 4-6 times the size of ommatidia; punctures on elytral striae larger than those on pronotum. Interstriae on elytral disc never wider than striae. Lateral margins of ventrites crenulate in most species ( If sculpture is coarse, the elytral interstriae are distinctly wider than the striae, at least on elytral disc, and the punctures on the striae are not larger than those on the pronotum (Figs 5,16,22). Protarsus of males always with a distinct sole of adhesive hairs at least on the basal tarsomere, usually on the two basal ones; the two basal tarsomeres thickened (Oliva 1989, Figs 127, 213, 332 Inner elytral striae (on disc) narrower than interstriae (Fig. 10)  Interstriae strongly convex, except the inner one (first interstria) on the anterior half; outer (eleventh) interstria costate, overhanging elytral margin on anterior half (Fig. 10A). Mesoventral process with anterior tooth strongly curved, slightly swollen, directed downwards; posterior angle raised, much lower than anterior tooth. Male genitalia with basal piece about half of total length. Parameres gradually acuminate; median lobe with spindle-shaped apical swelling (Fig. 10C)  Dorsum blackish with weak metallic sheen on head including labrum and pronotum, the latter testaceous on lateral margins and anterior angles. Elytra shading into dark brown at the apices and outer margins (Fig. 14B). Mesoventral process with anterior tooth weakly curved, directed posteroventrally; posterior angle weakly raised. Apical palpomere of maxillary palpi dark on apical one-third. Femora with pubescent portion darkened, glabrous portion testaceous. Male genitalia as in Fig. 15A (14) Outer elytral interstriae costate (Fig. 19B). Male protarsus with very strongly thickened basal tarsomere. Male mesotarsus with inner claw shorter and more strongly arched than outer claw. Male genitalia long, basal piece about half of total length. Parameres with the free sternal margin long and nearly straight (Fig. 20B)  Antennal cupula enlarged (about twice as long as the width of club). Tenth interstria convex, more strongly raised than flat eleventh interstria on the posterior half of the elytra. Mesoventral process with anterior tooth strongly curved. Apical notch with bottom very weakly produced into a triangle. Basal piece two-thirds of total length. Parameres rounded in apical half, apices not narrowed, but with a minute emargination that determines two teeth ..  Fig. 14C. Elytra without spine-like hairs (as in e.g. Fig. 22). First ventrite carinate between metacoxae, without lateral depressions. Head entirely melanic on dorsum, with metallic luster. Dorsum of head, pronotum and elytral striae coarsely punctate. Basal piece of male genitalia encasing only the base of the acuminate parameres .......B. nervulus-complex (no species found in Venezuela to date) -Basal pubescence of meso-and metafemora with limit transverse or briefly oblique. First ventrite carinate only between metacoxae; if carina longer, then dorsum of head without metallic luster (Fig. 11) : Fig. 127). Metallic luster on dorsum of head. Body shape broad but not very convex in lateral aspect (Figs 16A-B,  25C). Spine-like hairs only on the posterior third of the elytral margins, but may be difficult to see. Metaventral process large, strongly raised ( Fig. 25A Fifth ventrite with apical notch. Elytral apices produced, rounded in males, acute and convergent in females (Fig. 24). Pronotum and elytra with moderately coarse punctures; no micropunctation. Elytra never reticulate in males. Mesoventral process with large, curved anterior tooth. Male genitalia with parameres encased in basal piece in most of their length, with large, semicircular apical emargination, the row of hairs replaced by a single thick arista. Median lobe much longer than parameres, slender, straight, greatly swollen at apex ..