Brachypeplus Erichson, 1842

Kirejtshuk, Alexander G. & Kovalev, Alexey V., 2022, Monograph on the Cillaeinae (Coleoptera: Nitidulidae) from the Australian Region with comments on the taxonomy of the subfamily, Zootaxa 5103 (1), pp. 1-133 : 29-30

10. Genus Brachypeplus Erichson, 1842

Brachypeplus Erichson, 1842: 148 ;

Type species Brachypeplus planus Erichson, 1842: 148 ; recent, Tasmania (designated by Parsons, 1943: 155);

= Nitidulopsis Walker, 1858: 206;

Type species Nitidulopsis aequalis Walker, 1858: 206 ; recent, Sri Lanka (by monotypy).

= Tasmus Murray, 1864: 290 ;

Type species Brachypeplus planus Erichson, 1842: 148 ; recent, Tasmania (designated by Jelínek & Audisio, 2007: 478);

= Selis Murray, 1864: 302 ;

Type species Brachypeplus cuneatus Murray, 1864: 302 ; recent, Bacan Islands (“Batchian”) (designated by Jelínek & Audisio, 2007: 477);

= Palaeopeplus Powell et Cline, 2021: 23 , syn. nov.;

Type species Palaeopeplus cascus Powell et Cline, 2021: 23 ; fossil, Miocene Dominican amber.

Diagnosis. This genus seems to have the most generalized appearance among Australian cillaines, on the one hand, and a rather great diversity, on the other, and, therefore, it is not always easy to diagnose some its members among representatives of the subfamily. Nevertheless, it is characterized by an unique set of characters making it possible to reliably identify it: elongate oval to moderately elongate body; pubescent integument with longitudinal rows of longer hairs on elytra; head moderately short and moderately narrowed posteriorly, with medium-sized eyes located at base, labrum with subtruncate anterior edge and divided by the median suture into lobes, distinct antennal grooves subrectilinearly convergent, pregenal process and hypostomal sinus moderately narrow to somewhat wide; pronotum somewhat convex, with subtruncate to bi-sinuate base, more or less distinct posterior angles, shallowly emarginate anterior one, arcuate and usually moderately widely explanate sides; elytra about as long as combined width, with truncate apices and leaving uncovered at least three abdominal segments; laterosternites V and VI widened posteriorly; prohypomeran processes narrowly closed procoxal cavities posteriorly; prosternal process slightly or moderately widened at subtruncate apex, rarely subflatened at apex and slightly curved along procoxae; premesocoxal depressions rather short and moderately expressed; posterior edges of metaventrite between metacoxae subangular; femora, tibiae and tarsi of usual shape for the family, tarsomeres 1–3 lobed; male anal sclerite usually slightly exposed from under pygidial apex and with subtruncate to widely rounded apex (usually without crenellation), dorsoventrally compressed; aedeagus of usual bilobed structure; ovipositor of rather various in structure, usually with triangular gonocoxites clearly divided into outer and inner lobes and rectilinearly outlined at sides. The genus Brachypeplus shares most mentioned characters with the genera Brittonoma , Idosoronia , Leiopeplus , Onicotis and Matthewsianus gen. nov., although it can be determined after the above key to Australian genera and subgenera.

Notes on composition and synonymy. Murray (1864) included in this genus the following subgenera: Leiopeplus , Liparopeplus , Onicotis , Selis and Tasmus . Later Kirejtshuk (2001) erected the rank of Leiopeplus and Liparopeplus to two separate genera, and Onicotis is also regarded as a separate genus after Kirejtshuk (2008). Besides, Jelínek & Audisio (2007) treated Selis and Tasmus as synonyms of Brachypeplus . Kirejtshuk (2008) also considered Tasmus as synonym of Brachypeplus s. str. Erichson (1942) initially included two species in the genus Brachypeplus : B. planus and B. basalis . Later Murray (1864) both these species included in the subgenus Tasmus of the genus Brachypeplus . Parsons (1943) designated Brachypeplus planus as the type species of Brachypeplus and Jelínek & Audisio (2007) designated the same species ( B. planus ) as the type species of Tasmus . The characters indicated by Murray (1864) for distinguishing the species of Tasmus (mostly the raised ciliation of pronotal sides and very short abdominal ventrites 1 and 2) are, indead, rather variable and scarcely allow to discriminate a group of related species among congeners. As shown above, the Brachypeplus and Tasmus have the same type species. A recent more detailed comparison of Selis demonstrates that this taxon is also reasonable to regard as a synonym rather than separate subgenus, although after publications of Murray (1864), Grouvelle (1897, 2017), Gillogly (1962), and some others it recognized as a subgenus of Brachypeplus . Murray (1864) proposing the subgenus Selis emphasized on its 2–3-dentate mandibles and longer pygidium which is more narrowing apically than in other congeners, however these characters are rather variable as among some groups of the closely related species as sometimes even within one species. A further wide comparison could show more stable group difference for a reliable fixation of relationship between groups of the genus under consideration and make it possible to find a clear reason to split this genus into subgenera ( Brachypeplus and Selis ).

Murray (1864) put in the subgenus Selis only three species: Brachypeplus (Selis) apicalis , B. (S.) caudalis Murray, 1864 and B. (S.) cuneatus . In the catalogue by Grouvelle (1913) and later Brachypeplus (Selis) decoratus Grouvelle, 1917 , B. (S.) dorsalis Grouvelle, 1897 and B. (S.) ornatus Grouvelle, 1914 were added in this subgenus. They have a characteristic pattern of darkened spots and infuscations on their body and elytra, and also characteristic but not unique sculpture of integument. Later Gillogly (1962) described Brachypeplus kusaiensis which according to the opinion of the describer could be assigned to both Tasmus and Selis , coloration pattern and sculpture of the latter is completely different from six above-mentioned species, and recently two names of B. aequalis and B. dubreuili without clear relationship to initial members of Selis were interpreted in composition of this “subgenus ” (see below). In this monograph for “ Selis ” sensu Murray (1864) and “ Tasmus ” sensu Murray (1864) the terms apicalis -group of species ( Brachypeplus apicalis , B. cuneatus , B. dorsalis and B. nypicola sp. nov.) and basalis - group of species ( B. basalis , B. binotatus , B. blandus , B. macleayi , B. planus and probably B. wattsensis ) are used.

Palaeopeplus cascus described as a cillaeine by Powell & Cline (2021) from the Miocene Dominican amber without mention of any subfamiliar or generic diagnoistic character, however, one picture of the holotype of this species (“ Figure 2 , A”) published by these authors shows that this fossil species is a true member of the tribe Cillaeini s. str. because of its rather widened laterosternites V and VI. As the authors of Palaeopeplus cascus did not indicate any character making it possible to assign it to any genus or any subfamily (except “all abdominal tergites fimbriate”: p. 25), as well as a proper diagnosis or comparison with cillaeines and also as the pictures of the holotype of this species has only characters of the genus Brachypeplus (shape of head, pronotum and other observable upper sclerites, position of the medium-sized eyes, structure of the antennae and exposed abdominal laterosternites, traced sculpture of integument), it has no reason to consider it as a separate genus and it would be better to treat it as Brachypeplus cascus comb. nov. and respectively the generic name “ Palaeopeplus ” should be accepted as a junior synonym of Brachypeplus .

Figures

FIGURE 2. Adocimus (Belonotus) bartenevi sp. nov., orig. Holotype, male from QLD (“… 11 km W of Bald Hill, Mcllwaith Range…”); A: body, dorsal; B: head and thorax, ventral; C: head, dorsal; D: drawing of anterior part of frons, dorsal; E: lateral side of abdominal segments 5 and 6, dorsal; F: male anal sclerite and spiculum gastrale, ventral; G: tegmen, ventral; H: penis trunk, dorsal; I: proximal part of inner sac with armature. Scale bars: a = 1.0 mm to Fig. A; b = 1.0 mm to figs B–C and E–F; с = 0.25 mm to Figs G–I.