Metapogonia snizeki sp. nov. and a previously unknown female of M. elgonensis (Burgeon, 1945) (Coleoptera, Scarabaeidae, Melolonthinae, Diplotaxini)

Abstract Metapogonia snizekisp. nov. from northeastern Tanzania is described. The new species is compared with the morphologically closely similar species M. elgonensis (Burgeon, 1945). A previously unknown female of M. elgonensis is described, and the species is recorded from Uganda for the first time. Relevant diagnostic characters (parameres, shape of male protarsomeres, female pygidium) are illustrated.


Introduction
The Afrotropical diplotaxine genus Metapogonia Lacroix, 2008 (replacement name for Metagonia Kolbe, 1899) currently comprises 10 species from northwestern Africa (Senegal, Gambia) to southernmost Africa (Bezděk 2004). Nearly all of these species are known from primary descriptions only, with no comprehensive revisions and faunistic studies available. The members of Metapogonia differ from the species-rich and widely distributed genus Apogonia Kirby, 1819 mainly in the shape of the male genitalia. Parameres of Apogonia are often complex, asymmetrical, and only in some rare cases rather simple and laterally flattened, while those of Metapogonia are symmetrical and dorsoventrally flattened. This shape of the male genitalia is shared with the closely related Afrotropical genus Dichecephala Brenske, 1895. The main difference between Metapogonia and Dichecephala is in the shape of the clypeus. In both sexes of Metapogonia, the clypeus is simply rounded and slightly emarginated in the middle. The clypeus of Dichecephala is, however, strongly sexually dimorphic. The male possesses a clypeus triangularly produced anteriad, the apex of which is deeply emarginate and often bent upward. The clypeus of the Dichecephala female is less prominent and always displays two more or less visibly blunt teeth (but never broadly rounded as in Metapogonia).
The history of the generic nomenclature of this group of chafers is rather complicated. Kolbe (1899) proposed the genus-group name Metagonia as a subgenus of Apogonia. Subsequently, Moser (1918) and Burgeon (1945) elevated it to genus rank. This approach was followed by Bezděk (2004), who catalogued all Old World diplotaxine chafers. Unfortunately, all of these authors overlooked the fact that the genus-group name Metagonia Kolbe, 1899 was preoccupied by Metagonia Simon, 1893 (Aranae, Pholcidae). Nearly simultaneously, Lacroix (2008) and Özdikmen and Demir (2008) proposed replacement names for Metagonia Kolbe, 1899. Metapogonia Lacroix, 2008 was published on 4 April 2008, while Bezdekia Özdikmen & Demir, 2008 on 24 June 2008. Thus, based on the principle of priority, Metapogonia is the valid name for this group of chafers (see also Lacroix and Bezděk 2009 for a detailed discussion).
Studies of recently collected material of Diplotaxini from the northeastern part of the Afrotropical Region has revealed a new distinct species of Metapogonia as well as additional specimens of both sexes of M. elgonensis, a species previously known from the holotype male only.

Material and methods
A total of 139 specimens were studied. Specimens were examined with an Olympus SZX9 stereomicroscope; measurements were taken with an ocular grid. The habitus photographs were taken using a Canon MP-E 65mm/2.8 1-5× Macro attached to a Canon EOS 550D camera. Partially focussed images of each specimen were combined using Helicon Focus 3.20.2 Pro software. Specimens of the newly described species are provided with one printed red label: "Metapogonia snizeki sp. n. | holotypus [or paratypus with type number], sex symbol | Aleš Bezděk det. 2018". Exact label data are cited for the type material examined. Separate labels are indicated by a double vertical bar "||", lines within each label are separated by a single vertical bar "|". Information in quotation marks indicates the original spelling. My remarks and additional comments are placed in brackets, [p] -preceding data (within quotation marks) are printed; [hw] -the same but handwritten. HT -holotype, PT -paratype. The map was composed using SimpleMappr (Shorthouse 2010).
The following codes identify the collections housing the material examined:
Head. Clypeus transverse, broadly rounded, slightly emarginate in the middle, with coarse and dense punctures. Frons and vertex less densely punctate. Eye canthus prominent, largely fused with clypeus; borderline between eye canthus and clypeus invisible. Eye large, distinctly extended beyond the canthus. Antenna with 10 antennomeres; club trimerous, slightly shorter than antennal shaft. Antennomeres 1-7 with few isolated, erect setae; club sparsely covered with moderately long, erect setae. Labrum transverse, narrow, completely covered by clypeus, thus not visible from above, with coarse irregular punctures bearing moderately long, erect setae.
Pronotum transverse, convex, widest at about the middle, base broader than anterior margin. Anterior angles prominent, acute-angulate; posterior angles obtuse. Anterior margin with membranous border; anterior marginal line incomplete, interrupted in the middle. Lateral marginal line complete; basal marginal line absent. Punctation coarse, punctures separated by 0.5 or less of their diameter, but never confluent. Scutellum triangulate, approximately as wide as long; apex broadly rounded, sparsely punctate in basal half, nearly impunctate apically, completely bare.
Elytron convex, widest about at middle; sutural angle obtuse-angulate. Surface of elytron covered with coarse, irregular punctures. Basal half of epipleuron with a row of short, recumbent setae. Apical half of lateral margin of elytron with membranous border. Macropterous.
Sexual dimorphism. Female differs from male in the following characters: body length 6.8-7.8 mm (102 specimens measured); antennal club shorter, as long as 6 antecedent antennomeres. Tarsomeres without patches of macrosetae ventrally; pygidium less prominent, nearly flat, with distinct tooth in the centre of lateral margin (Fig. 10).
M. snizeki sp. nov. differ from those of M. elgonensis in the shape of the genitalia (compare Figs 6,7 and 8,9) and by the shape of protarsomeres, which are more dilated in M. snizeki sp. nov. (Figs 12, 13). The females of these two species are very difficult to differentate from the dorsal view, the best identification character seeming to be the shape of the pygidium. The tooth of the pygidium is located nearly in the middle of its lateral margin in M. snizeki sp. nov. (Fig. 10), but distinctly more basally in M. elgonensis (Fig. 11).
Collecting events. The majority of type material was captured when attracted to light (M. Snížek pers. comm.).
Etymology. The species is named after Miroslav Snížek (Homole near České Budějovice, Czech Republic), one of the collectors of the new species.