Bolbaoeer, Vulcano, Martinez and Pereira

Gussmann, S. M. V. & Scholtz, C. H., 2001, Systematic revision of the Afrotropical genus BolbaOEer Vulcano, Martinez and Pereira (Coleoptera: Scarabaeoidea: Bolboceratidae: Bolboceratinae), with descriptions of eight new species, Journal of Natural History 35 (7), pp. 1013-1084 : 1016-1031

Genus BolbaOEer Vulcano, Martinez and Pereira

BolbaOEer Vulcano, Martinez and Pereira, 1969: 169 ; Nikolajev 1979: 189; 1982: 35; Krikken, 1984: 39.

Type species. Bolboceras princeps Kolbe, 1894 , by original monotypy.

The genus BolbaOEer was erected by Vulcano, Martinez and Pereira (1969) as a monotypic genus with Bolboceras princeps Kolbe designated as the type species. Although the etymology of the name`BolbaOEer’ was not explained by Vulcano, Martinez and Pereira (1969),`BolbaOEer’ was obviously assumed to be of neutral gender as evident from the usage of neutral endings of species names in all subsequent literature ( Nikolajev, 1979, 1982; Krikken, 1984). In our opinion, this constitutes an error for the following reasons:`BolbaOEer’ is clearly composed of two words, the stem word`bolb’ which is derived from the noun `b o lb o f ’, Greek for`swelling, bulb’ and referring to the bulbous, onion-shaped outline of the beetles, and the word`aOEer’. The latter word might be a misspelling of the Latin adjective`afer’ which means`African’. It might, on the other hand, simply be a shortened or modi®ed version of`BolbocaOEer’, a genus name also erected in Vulcano, Martinez and Pereira (1969).`CaOEer’ is a Latin adjective and translates to`pertaining to the Ka rs’, referring to the inhabitants of`CaOEraria’. In both cases the endings of the Latin adjectives are masculine and the gender of the species names should have been adjusted accordingly. We therefore perform the required gender adjustments in the present paper and furthermore wish to indicate that the same gender adjustments need to be made in any future papers dealing with the genus BolbocaOEer Vulcano, Martinez and Pereira.

With only the type species included in the genus BolbaOEer , the generic description by Vulcano, Martinez and Pereira (1969) is of somewhat limited use because many detailed features mentioned by the authors represent speci®c characteristics of the type species that are not applicable to all the other, later included, members of the genus and thus do not de®ne the genus as such. The simultaneous appearance of a paper by Petrovitz (1969) was obviously unknown to Vulcano, Martinez and Pereira and vice versa. Petrovitz (1969) described four new species and the so far unknown females of one species but placed them all in the genus Bolboceras Kirby. It was not until Nikolajev (1979, 1982) and Krikken (1984) that those and other species were ®nally transferred to BolbaOEer . Nikolajev (1979) proposed and described BolbaOEroides as a subgenus of BolbaOEer and designated Bolboceras validum Klug as type species of the new subgenus. Besides the existing type species Bolboceras princeps Kolbe , he included Bolboceras splendidum Petrovitz in the nominal subgenus BolbaOEer . But interestingly enough Nikolajev seemed to have abolished, i.e. failed to mention this concept in the subsequent revision of BolbaOEer ( Nikolajev, 1982) . Shortly afterwards Krikken (1984) accorded BolbaOEroides generic rank. We support Krikken’s decision as we believe that the two genera are not that closely related. Some of the diOEerences between BolbaOEer and BolbaOEroides are explained below under`Comments and general morphology’.

Description male and female

Body length 15.6±27.0 mm. Colour variable, light to dark brown, head and pronotum sometimes slightly darker than elytra. Dorsal surface of head asetose. Outer margin of male mandible variable, i.e. rounded to strongly sinuate and always anteriorly more strongly curved inward. Outer margin of female mandible as in male but sinuate curvature always less pronounced. Labrum strongly bisinuate but anteromedially steeply sloping downward to a very distinct toothlike process (e.g. arrow in ®gure 2c); with feebly (e.g. ®gure 2c) to strongly developed (e.g. arrow in ®gure 2a), continuous (e.g. ®gure 2a) or interrupted (e.g. arrows in ®gure 2e) transverse carina above toothlike process; endpoints of carina sometimes connected to carinate margin of labral lobes (e.g. ®gure 2e); anterior carinate labral margin obsolete above toothlike process. Clypeus of male with distinctly elevated, transverse anterior carina; with distinct lateral carina from endpoint of anterior carina extending to above antennal insertion in almost straight line, from there extending posteriorly in a slightly curved line past eye-canthus on frons, reaching posterior end of frons (e.g. ®gure 2a); lateral carina always distinctly raised above antennal insertion; mostly with bituberculate, feebly arcuate or feebly bisinuate transverse posterior carina; position of tubercles variable, from in line with antennal insertions (e.g. ®gure 2c) to in line with clypeo-fronta l transition; posterior carina variable in length, from much shorter to slightly longer than anterior carina; sometimes with strongly arcuate, transverse posterior carina, medially raised to single or feebly bifurcate horn which is medially connected to anterior clypeal margin (®gure 2b). Clypeus of female as in male but lacking posterior transverse carina. Frons of male more or less ¯at, but feebly depressed, rarely distinctly concave posterior to posterior clypeal carina; with small carinate process between eye and endpoint of lateral carina on frons (e.g. arrow in ®gure 2b). Frons of female with distinctly to strongly raised bituberculate, transverse carina; position of carina varying from slightly posterior to clypeo-frontal transition (e.g. ®gure 2e) to slightly posterior to postero-genal angle; carina straight and varying from half length of to as long as anterior clypeal carina; with small carinate process between eye and endpoint of lateral carina on frons, as in male. Antennal club feebly elliptical, i.e. almost circular, slightly shorter than diameter of eye; distinct glabrous area on basal segment variable in size, from one-third to one-half of exposed surface. Pronotum of male with disc ¯attened; anterior margin varying from medially very feebly raised to bituberculate / bihorned (e.g. ®gure 2a and arrow in ®gure 4o) to rarely produced into arcuate horn with bifurcate apex (®gure 3g, h), in dorsal view varying from not projecting over head (e.g. ®gure 2d) to (rarely) strongly, almost horizontally projecting over head (e.g. ®gure 2b); lateral margin entire; armature variable (see species descriptions) but usually with transverse swollen, non-carinate areas and protrusions along posterior margin only; punctation variable (see species descriptions) but always with large, often conūent punctures present towards sides; lateral margin entire. Pronotum of female with disc convex; anterior margin in frontal view medially more or less raised and more or less bisinuate, in dorsal view more or less arcuate; with transverse, feebly to strongly carinate, swelling at the median portion of disc (e.g. ®gure 6b); swelling medially variably constricted and depressed, rarely divided into two distinct, tuberculate swellings; feeble antero-lateral, longitudinal swelling always present (e.g. ®gure 6b); punctation variable but always with large, often conūent punctures lateral and posterior to median swelling; lateral margin entire. Scutellum deltoid (®gure 1d); basal width about 1.5 Ö length; lateral margin medially abruptly curved (arrows in ®gure 1d); with ®ne or large punctation. Elytron with anterior margin not upturned; striae moderately impressed, their punctures small (®gure 1d) but with variable distance between them (see species descriptions); intervals nearly ¯at, with single punctation (®ne punctures of variable density); sutural stria terminating at scutellum in a feebly arcuate line, second stria slightly curving in towards scutellum but then obsolete and not reaching scutellum (®gure 1d). Prosternum behind procoxae with shape as in ®gure 1b, c; with protruding median, longitudinal carina as in ®gure 1b, c. Metasternum (®gure 1a) with disc more or less ¯at; process anteromedially depressed and with rounded, swollen lateral parts; with longitudinal, median suture terminating very close to meso-metasternal suture, but not reaching it; mesometasternal suture present at top of concave, medially steep, sloping anterior declivity; areas anterior to lateral parts of meso-metasternal suture gradually sloping downward; distribution of setose punctures as in ®gure 1a (larger dots). Protibia of normal shape, i.e. non-dilated (as in ®gure 6a, b); ®ve- to seven-dentate. Protibial spur elongate, slightly shorter, as long as or slightly longer than ®fth tarsomere, apex sometimes modi®ed. Protarsus always with ®rst tarsomere shorter than ®fth tarsomere, about as long as tarsomere 2, 3 or 4. Metatrochante r of male of unmodi®ed shape in most (®gure 12b), of modi®ed shape in some species (e.g. ®gure 12c); surface with setation variable in distribution, density and length. Metatrochanter of female as in male but setation always sparser. Metafemur of male in ventral view with distinct longitudinal line of densely spaced setose punctures in posterior third, otherwise with setation variable in length and density. Metafemur of female as in male but with setation always sparser. Metatibia in lateral view elongate, gradually broadening apically (®gure 1f); subapical carina with one lateral distinct lobe, bilobed (arrows in ®gure 1f) or rarely trilobed, i.e. with small additional median lobe; with toothlike projections arranged in two rows above subapical carina (®gure 1f); with outer spur slightly arcuate (®gure 1e, f), sometimes hooked (®gure 7b). Metatarsus lacking subapical setae on tarsomeres 2±4. Underside with dense and long setation; abdominal sternites and pygidium (last visible tergite) in males often strongly modi®ed, but modi®ed to a lesser degree in most females.

Male genitalia with typical genital capsule, its setation moderately long, sometimes very long; aedeagus with well-developed, strongly sclerotized and apically narrowing parameres. Female genitalia not considered.

Distribution. Representatives of the genus are found in most parts of subsaharan Africa with the exception of very arid and possibly densely wooded tropical rainforest regions.

Comments and general morphology

With an average body size of about 20 mm, members of BolbaOEer are the largest Afrotropical bolboceratine taxa. Intraspeci®c variation in body size can, however, amount to as much as 6.7 mm. No obvious diOEerence in body size has been observed between the two sexes of any given species.

As in other bolboceratine taxa, the colour of the integument varies, depending on the degree of sclerotization, from light brown in freshly emerged specimens to dark brown in older specimens. It is therefore not a useful character to distinguish between species. In some BolbaOEer species , the head and pronotum might be slightly darker than the elytra but this is not always consistent for all specimens within a species.

The outline of the outer margin of the mandible varies in dorsal view interspeci®cally from rounded to strongly sinuate. While the diOEerence between a rounded and strongly sinuate outer margin (compare ®gure 2a with 2e) is clear, the diOEerence between a very feebly sinuate and feebly sinuate outer margin (compare ®gure 2b with 2c) is more di cult to detect. In addition, any sinuate curvature will always be less pronounced in the female sex.

The shape of the labrum in dorsal view is one of the important generic characters to distinguish BolbaOEer from most though not all other bolboceratine genera, but in particular from BolbaOEroides. In the former genus the labrum is consistently strongly bisinuate but antero-medially steeply sloping downward to a very distinct toothlike process. In BolbaOEroides, on the other hand, the labrum is only very feebly bisinuate and not steeply sloping downward antero-medially. The carinate anterior labral margin is, however, sometimes medially protruding a little but never forming a distinct toothlike process. The only other taxa with an almost identically shaped labrum, besides BolbaOEer , are some of the Afro-Indian Bolboceratops Krikken species (see illustrations in Carpaneto, Mignani and Piattella, 1993) but the anterior carinate labral margin is always continuous as opposed to being mostly obsolete medially as in BolbaOEer . There are many other major diOEerences between the latter two genera such as body size, cephalic and pronotal armature and punctation, shape of metasternum, male genitalia etc. A toothlike process on the labrum is de®nitely absent in all genera endemic to southern Africa. Comments are withheld on the Afrotropical genera BolbocaOEer and Mimobolbus as not all of their members have been properly examined yet.

With the exception of two species, the clypeal and frontal armature for males of BolbaOEer is very similar (see description above). The position of the posterior transverse clypeal carina often varies more intra- than interspeci®cally. The most signi®cant diOEerences between males of BolbaOEer and BolbaOEroides are as follows: in the latter genus the lateral end-points of the anterior clypeal carina are connected to the antero-lateral clypeal corners with a short, diagonal carina while this diagonal carina is lacking in the former genus; in BolbaOEroides the posterior clypeal carina is either trituberculate or bituberculate with distinctly raised median part and always much longer than the anterior carina while, in BolbaOEer , it is bituberculate and usually shorter, at most slightly longer than the anterior carina. In females of BolbaOEer the equivalent of the transverse, posterior clypeal carina is shifted posteriad and positioned on the frons. This carina is distinctly bituberculate, strongly raised and straight. Its position is inter- and intraspeci®cally variable, from being positioned between the eye-canthi (as in ®gure 2e) to slightly posterior to the postero-lateral genal angle. The length of the carina also varies inter- and intraspeci®cally, from being distinctly shorter to as long as the anterior clypeal carina. In females of BolbaOEroides a posterior transverse carina is also absent on the clypeus but a carina is present on the frons. This carina is bituberculate but also has a distinctly raised median part.

A consistent diOEerence between BolbaOEer and BolbaOEroides in both sexes is the shape of the eye-canthus: the sides of the eye-canthi are strongly diverging caudad in the latter but subparallel or converging caudad at various degrees in the former genus. Another cephalic diOEerence is the presence of a small angular carinate process between eye and endpoint of the lateral carina on the frons in male and female BolbaOEer (as in ®gure 2b) whereas no such process is found in members of BolbaOEroides.

The antennal club is of the same, almost circular shape and of the same size, i.e. slightly shorter than diameter of eye, in all BolbaOEer species. A distinct glabrous area is present on the basal segment but varies in size inter- and often intraspeci®cally, from one-third to one-half of the exposed surface.

The shape and armature of the pronotum follows a typical pattern for the males of most BolbaOEer species. The pronotum is characterized by its relative broadness, by its ¯attened disc and by the presence of protrusions and transverse swollen, noncarinate areas along the posterior margin (e.g. ®gure 6a). The only exceptions are the males of two species, B. barbatus and B. tenuelimbatus . The male of the former species has an additional pair of horns near the anterior pronotal margin (®gure 3j), while males of the latter species lack horns / tubercles on the pronotal surface but instead possess an arcuate horn with bifurcate apex produced medially from the anterior pronotal margin (®gure 3g, h). Furthermore, the anterior pronotal margin is medially modi®ed to various degrees (see description). It is never modi®ed in male BolbaOEroides and the pronotal shape and ornamentation diOEer signi®cantly as well: pronotum not as broad, pronotal disc not ¯attened but with two to four protrusions positioned above the anterior pronotal declivity and with an additional pair of protrusions present antero-laterally. When describing the arrangement of protrusions, i.e. horns / tubercles, along the posterior pronotal margin in BolbaOEer males, we distinguish between an outer pair of horns / tubercles (e.g arrows in ®gure 4a) with each protrusion positioned approximately opposite the elytral humeral callus, and an inner pair of horns / tubercles (e.g. arrows in ®gure 4b), positioned closer to the midline. An additional median protrusion, positioned on the midline, might be present as well (e.g. arrow in ®gure 4d). While most species possess at least an outer pair of horns / tubercles, two species lack an outer pair of protrusions and only possess an inner pair of protrusions: B. splendidus as in ®gure 3d, e and B. guineaensi s as in ®gure 3o. In major males protrusions are developed the most but become progressively smaller, more approximated, i.e. shift along the posterior pronotal margin closer towards the midline, in intermediate and minor males (e.g. ®gure 4a±c). The sexually dimorphic females of BolbaOEer have an overall convexly shaped pronotum with relatively uniform armature. The anterior margin is hardly modi®ed (see description). Females of all species are characterized by a transverse, feebly to strongly carinate, swelling at the median portion of disc. This swelling is medially variably constricted and depressed. If the swelling is medially more strongly depressed, then the swelling has a distinct bisinuate outline in frontal view (e.g. ®gure 3c). Length and shape of the swelling were, often exclusively, used by Nikolajev (1982) in the identi®cation key for females. We found that in most cases the swelling as a diOEerentiating character cannot be used with con®dence as interspeci®c diOEerences are subtle and very di cult to describe or illustrate accurately. Only with su cient material of diOEerent species and with experience is it possible to depict the diOEerences. One exception are females of B. tenuelimbatus : the transverse carina is medially and laterally obsolete, dividing the swelling at median portion of disc into two strongly protruding tuberculate swellings (®gure 3i). Because of the general scarcity of morphological diOEerences between BolbaOEer females, we nevertheless included the transverse pronotal swelling as a character in all species descriptions.

The pronotal punctation in both sexes serves as a useful character to distinguish at least between species-groups. Punctation is very similar in closely related species and some intraspeci®c variation mainly relating to the density of punctures, does occur as well. We de®ne the terms to describe pronotal punctation as follows:`®ne punctures’ are single, impressed points, appearing as pin-pricks;`small’ and`large’ punctures or any punctures of intermediate size, on the other hand, are fairly shallow, funnel-shaped depressions with a`®ne puncture’ in the centre. This is only visible under higher magni®cation but when examining the overall pattern of pronotal sculpture at lower magni®cation, all the depressions simply appear as punctures of diOEerent sizes, spaced at diOEerent densities. In a few cases we refer to`small, deep punctures’ and`large, deep punctures’. These are also funnel-shaped depressions with a pin-prick in the centre, but they are distinctly less shallow than other punctures.

No obvious diOEerences were found in the shape of the scutellum between BolbaOEer species. The deltoid shape and the medially abruptl y curved lateral margin (®gure 1d) are very similar to BolbaOEroides and the southern African genus Namibiobolbus Krikken. Only the punctation can be used to distinguish between some of the BolbaOEer species-groups.

The elytral sculpture is very uniform for all BolbaOEer species. The only diOEerences worth including in the descriptions, are the spacing of strial punctures and the spacing of the single punctation between two striae.

The prosternum behind the procoxae is shaped as in ®gure 1b, c in all BolbaOEer species. The same shape is shared by Namibiobolbus and at least some of the BolbaOEroides species.

The metasternal shape, as in ®gure 1a, is shared by the southern African genus Bolboceratex Krikken and some BolbaOEroides species but diOEers from Namibiobolbus .

While certain characters pertaining to the legs are common to all species of BolbaOEer , some characters show interesting and unusual modi®cations at species level, but are often restricted to the male sex. The average number of protibial denticles is ®ve in the majority of species, six in some species and rarely seven as an intraspeci®c variation. An unmodi®ed elongate, acuminate protibial spur is shared by most species, but a modi®ed protibial apex is found in males of two species-groups. The metatrochanter in ventral view is of unmodi®ed shape (e.g. ®gure 12b) in most, but of modi®ed shape in males and females of the B. coriaceus species-group (e.g. ®gure 12c). Setation (distribution and length) on the metatrochan - teral surface in ventral view can be used as a supportive character for identi®cation at species level. Although the length of setae is di cult to describe, even in relative terms, we refer to ®gure 12n illustrating short setation in the apical area of the metatrochanter and to ®gure 10a illustrating very long setation along the posterior margin of the metatrochanter. The basal area of the metatrochanter is the area where the metatrochante r is attached to the metacoxa while the apical area is situated at the opposite end where the metatrochanter attenuates to a pointed tip. Setation on the metatrochanter, and on other appendages for that matter, is always sexually dimorphic insofar that larger areas are covered with setae and that setation is denser in males compared to females. In a similar fashion, the setation of the metafemur also diOEers between species and the two sexes. In ventral view the parts of the metafemur are de®ned as follows: basal area is the area where the metafemur is attached to the metatrochanter while the apical area is closest to the metatibia. The anterior non-carinate rounded margin is the margin facing toward the head of the specimen whereas the posterior margin faces toward the posterior end of the abdomen. The posterior margin, level with the metafemur in ventral view, is carinate near the metafemoral apex but becomes obsolete yet still visible as a line of setose punctures toward the base. At the apex of the metafemur is a second posterior margin, directly beneath the other one, and forming the margin of the dorsal side of the metafemur. This latter margin is carinate over its entire length and becomes visible in the basal part of the metafemur. When referring to`posterior margin’, we only refer to the former not the latter margin. Common to all species of BolbaOEer , is a distinct line of densely spaced setose punctures in the posterior third of the metafemur, subparallel to the posterior margin. Likewise a line of variably dense setae is always present along the posterior margin. There is usually a broad band of randomly scattered setae, i.e. not arranged in a line, along the anterior margin, approximately covering the anterior third of the metafemur. Important for species

FIG. 11. Distributional records: BolbaOEer bremeri (E); B. splendidus (_); distributional overlap: B. bremeri and B. splendidus () ; B. barbatus (+); B. tenuelimbatus (y).

identi®cation and diOEerences between the two sexes are density and length of setation, particularly in basal areas and areas between anterior setose band and mentioned distinct line in posterior third, as well as in the area between the distinct line and posterior margin. No diOEerences are apparent in shape, sculpture and setation of the metatibia between BolbaOEer species. A hooked outer metatibial spur in males of B. splendidus species-group is the only unusual exception.

Ventral modi®cations on the visible abdominal sternites and on the pygidium are typical for BolbaOEer and diOEer between species and sexes. Terminology is de®ned as follows: only six abdominal sternites are visible in Bolboceratidae and the sternites are numbered as such, i.e. sternite 2 is the second visible abdominal sternite and sternite 6 is the last visible sternite, also termed`urosternal plate’ by some of the other authors (e.g. Carpaneto et al., 1990). In the illustrations, the abdominal sternites bear the respective numbers except for the terminal sternite which is not numbered. The eighth, i.e. terminal, tergite is the pygidium and generally large in size. The gap or area between the sternite 6 and the pygidium through which the genitalia would be protruded for copulation is shaded in the detail illustrations. Both, sternite 6 and the pygidium, are normally at least partially or even fully retracted under the elytra, leaving only a greater or smaller part of the pygidium exposed in posterior view of the specimen. Whenever possible, we selected those specimens for illustrations that had the entire pygidium exposed. The sternal and pygidial modi®cations are stable and among the most important characteristics for the identi®cation of species and their sexes. Equally important are the male aedeagi which are very species speci®c and, with the exception of one species, intraspeci®cally not variable. The median lobe, between the parameres, is often partially visible (e.g. ®gures 19h, i, 22l, m) and sometimes part of the internal sac is everted too (e.g. ®gure 10c±e). If the internal sac is fully everted, the parameres are apically forced apart as shown in ®gure 8g. We should also mention here the distinct diOEerences between the aedeagal types of BolbaOEer and BolbaOEroides: the aedeagal type of the former is characterized by the strongly sclerotized, apically usually narrowing parameres while the aedeagal type of the latter is less sclerotized, broad, often with apically rounded parameres and with additional folded lobes (see illustrations in Krikken, 1978) and thus more similar to the southern African genera Namibiobolbus and Meridiobolbus Krikken. External female genitalia ®nd no mention in bolboceratine literature because of the absence of any clearly de®nable structures. At most, intertwined, folded membranes can be found when opening up the abdomen. The genus BolbaOEer might, however, be an exception. In one female of B. bidenticollis (Fairmaire) we could see a partially setose structure in the gap between sternite 6 and the pygidium that reminds one of the structure of a male genital capsule. Although not undertaken for this study, interspeci®c diOEerences that obviously exist in females, should be investigated further.

Based on a number of apomorphic character states we were able to de®ne four distinct species-groups, each consisting of closely related species. Only four species could not be grouped and have to be treated as separate entities. The identi®cation keys for males and females con®rm the groupings with members of a species-group always keying out together although the sequence diOEers between the keys. Descriptions and discussions of species under`Treatment of species’ follow the same order in which species are keyed out in the identi®cation key for males.

The brief diagnoses of the four species-groups are as follows: