Balleriodes, Grebennikov, 2021

Grebennikov, Vasily V., 2021, Phylogenetic placement of a new paleoendemic pill scarab from the Udzungwa Mountains, Tanzania, triggers biogeographic interpretations (Coleoptera: Hybosoridae, Ceratocanthinae), Fragmenta entomologica 53 (2), pp. 283-298 : 288-290

Balleriodes gen. nov.

Type species. Balleriodes sphaera sp. nov.,

here designated.

Diagnosis. The only known species of the genus can be immediately recognized among all pill scarabs (including most similar Synarmostes ) by the unique combination of the following easily observed characters: body black, non-metallic, without prominent pubescence or punctures (although sparse fine surface sculpturing is present), in conglobate position nearly circular in dorsal view and nearly globular in 3-dimensional shape. Most notably (and uniquely with allopatric Synarmostes ), adults of the new genus have elytra with markedly developed longitudinal striation only in posterior halves. Adult beetles of the new genus additionally differ from those of Synarmostes in having a single apical outer spur on protibia apices (two in Synarmostes ), head lacking a transverse furrow on vertex, parameres with a basal projection, and relatively larger basal piece of male genitalia (Alberto Ballerio, personal communication). Additionally, the type species of this monotypic genus displays two characters seemingly unique within all of Ceratocanthinae (Alberto Ballerio, personal communication): remarkably long and dense setae on the fore tarsi (arrow in Fig. 2L ) and the transparent membrane adjacent to the ventral surface of parameres (arrows in Figs 2P–R ). Description. Body black; without pubescence; without much microsculpture; non-metallic; in fully conglobate position visible part of legs (tibiae) and elytral apical halves often covered with dirt-like coating ( Figs 3–4 ); neatly circular in dorsal view and nearly globular in 3-dimensional shape. Enrollment coaptations (ability to make a perfect ball) present. Head with interocular bridge (=“genal canthus”) completely subdividing compound eye into dorsal and ventral parts ( Fig. 2A ); dorsal eye small, ellipse-shaped, with major axis about four times greater than minor axis ( Fig. 2A ). Antennae with 10 antennomeres ( Fig. 2G ). Mandibles in apical part without teeth (in addition to mandibular apex, Figs 2E–F ). Maxillae with distal palpomere longer than combined length of both preceding ones ( Fig. 2C ). Pronotum evenly convex, sparsely, and shallowly punctured, its anterior and posterior margins not swollen ( Fig. 1D ), marginal bead complete. Elytra longitudinally striate on dorsal side in posterior half, and not striate in anterior half, with sparse shallow transverse comma-shaped punctures. Metathoracic wings absent. Protibiae with fine serration on distal third of outer side and with a larger apical outer tooth ( Fig. 2L ). Male genitalia with parameres almost symmetrical, basally with a projection ( Figs 2P–R ). Female genitalia and sexual dimorphism not studied.

Species composition and distribution. This genus is monotypic and its known distribution is limited to the type locality of its only species (see below).

Etymology. The generic name is a patronymic, derived by adding the Latin suffix - odes to the family name of Alberto Ballerio (Brescia, Italy), in recognition of his role in triggering my interest in the evolution of pill scarabs. Gender masculine.

Figures

Fig. 2 – Balleriodes sphaera gen. et sp. nov., paratypes (A-R, specimen 8969, S, specimen 8752), details. A-B, head, fronto-dorsal (A) and frontal (B); C, maxilla; D, labrum; E-F, mandibles; G, antenna; H: labium; I-J, elytron in ventral view showing phoretic mites (J, enlarged); K, prothorax, ventral view; L-N, fore, middle and hind left legs; O, pterothorax, ventral view; P-R, phallobase and parameres, right lateral (P), left lateral (Q) and dorsal (R) views; abdomen, with male genitalia in situ. Images are not to scale.

Fig. 3 – Habitus of select ingroup and outgroup pill scarabs, dorsal view; images are to scale.

Fig. 4 – Habitus of select ingroup and outgroup pill scarabs, left lateral view; images are to scale.

Fig. 1 – A, Distribution of Balleriodes sphaera gen. et sp. nov. and potentially related and/or similar pill scarabs in Africa and Madagascar. B-F: Balleriodes sphaera gen. et sp. nov., holotype, habitus (B: left lateral, C: dorsal, D: ventral; E: anterior, F: posterior).