Waidelotus hoffeinsorum, Bukejs & Alekseev & Pollock, 2019

Bukejs, Andris, Alekseev, Vitalii I. & Pollock, Darren A., 2019, Waidelotinae, a new subfamily of Pyrochroidae (Coleoptera: Tenebrionoidea) from Baltic amber of the Sambian peninsula and the interpretation of Sambian amber stratigraphy, age and location, Zootaxa 4664 (2), pp. 261-273 : 264-267

Waidelotus hoffeinsorum sp. nov.

( Figs 1–8 )

urn:lsid:zoobank.org:act:85C197A5-A166-4C50-823D-BC739E0B8214

Type material. Holotype: No. 587-4 [ CCHH], adult, male. Complete beetle inclusion with exposed genitalia in small amber piece embedded in block of GTS-polyester resin with dimensions 13×7× 5 mm. Syninclusion: absent.

Type strata. Baltic amber. Mid-Eocene (Bartonian) [see discussion below].

Type locality. Yantarny settlement (formerly Palmnicken), Sambian (Samland) peninsula, the Kaliningrad region, Russia .

Etymology. Patronymic, this new species is named in honour of Christel and Hans Werner Hoffeins (Hamburg, Germany), who provided this interesting inclusion for examination and supported the authors with advice, literature sources and enthusiasm for amber study.

Description. Male holotype. Body elongate, subparallel-sided, flattened dorsally, slightly convex ventrally; unicolorous brown. Vestiture: moderately densely covered with short, homogeneous semierect setae dorsally, and with fine, less conspicuous setae ventrally. Head and pronotum with small (nearly as large as one eye facet), dense punctures; elytra and venter with finer punctation, elytral punctation irregular. Body length 4.7 mm, pronotum length 0.7 mm, elytra length 3.7 mm.

Head prognathous, without distinct constriction behind eyes. Frons almost flat; vertex slightly convex. Compound eyes large, with vertical diameter about 2× transverse diameter, prominent, distinctly emarginate near antennal insertion, coarsely faceted, without interfacetal setae, widely separated. Clypeus transverse, convex, widely rounded apically; frontoclypeal suture distinct. Labrum free, strongly transverse, about 3× as wide as long, with almost straight anterior margin. Mandibles short, curved, with apex bifid. Maxillary palpi 4-segmented; terminal palpomere cultriform, about 2.5× as long as palpomere 3. Antennae 11-segmented, filiform; moderately long, extending about to basal one-third of elytra; bearing small setiferous punctures. Scape subcylindrical, about 1.3× as long as pedicel; pedicel cylindrical, 0.6× as long as antennomere 3; antennomeres 3–10 elongate, slightly dilated apically; antennomere 11 slightly longer than antennomere 10, about 3.1× as long as wide, pointed apically. Relative length ratios of antennomeres 1–11 equal to 12:9:16:15:15:12:12:11:11:10:13. Antennal insertions exposed, widely separated.

Pronotum transverse, about 1.3× as wide as long, with maximum width in posterior one-fourth, gradually narrowed anteriad, slightly narrower than basal width of elytra; pronotal disc slightly convex, with shallow, indistinct medial impression, without posterior pits situated near posterior angles; lateral margins smooth and slightly rounded in anterior half, but margined and oblique straight in basal half; posterior margin slightly trisinuate, with fine submarginal groove weakly developed; anterior angles weakly developed, obtusely rounded; posterior angles distinct, orthogonal.

Scutellar shield trapezoidal, slightly transverse, about 1.2× as wide as long, moderately large, with impressed anterior portion; densely covered with fine punctation and short semierect setae.

Elytra elongate, about 1.9× as long as wide, subparallel-sided, widest in posterior one-third; humeri prominent. Epipleura narrow, gradually narrowed posteriad, extending to nearly posterior margin of abdominal ventrite 3 (not reaching elytral apex), covered with fine, dense punctures.

Hypomera each with depressed posterior portion. Prosternum with anterior margin not produced anteriorly; prosternal process narrow, apparently incompletely separating prothoracic coxae. Prothoracic coxal cavities open posteriorly. Trochantins exposed. Mesothoracic ventrite with longitudinal sharp carina medio-posteriorly, and posterior margin with narrow process, separated from mesothoracic episterna by complete suture. Metathoracic ventrite wide and long, disc convex; discrimen well developed in posterior half.

Legs long and slender. All coxae narrowly separated; prothoracic coxae large, conical, projecting, mesothoracic coxae conical, slightly smaller than prothoracic coxae; metathoracic coxae transverse, elongate-oval, impressed posteriad, with transverse fine carina anteriorly. Trochanters heteromeroid. Femora slender, flattened, metathoracic femora 4.2× as long as wide; femora and tibiae nearly equal in length. Tibiae long, slender, almost straight, with two moderately long, simple paired apical spurs of equal length. Tarsal formula 5-5-4; penultimate tarsomere of all tarsi deeply bilobed (more than half of its length); antepenultimate tarsomere of each prothoracic tarsus slightly bilobed, antepenultimate tarsomere of each mesothoracic tarsus slightly bilobed ventrally, antepenultimate tarsomere of each metathoracic tarsus slightly widened apically. Pretarsal claws small and thin, symmetrical, appendiculate (with small denticle basally).

Abdomen with five visible, similar, freely articulated ventrites; ventrite 5 with posterior margin widely and shallowly emarginate. Relative length (medially) ratios of ventrites 1–5 equal to 5:8:7:6:6.

Male genitalia ( Fig. 7 ).

Remark. Exposed genitalia and ventrite 5 with emargination indicate that the specimen is male.

Figures

FIGURES 1–3. Waidelotus hoffeinsorum gen. et sp. nov., holotype, No. 587-4 [CCHH]: 1 – habitus, ventrolateral view; 2 – habitus, dorsolateral view; 3 – habitus, ventrolateral view. Scale bars = 1.0 mm.

FIGURES 4–5. Waidelotus hoffeinsorum gen. et sp. nov., holotype, No. 587-4 [CCHH]: 4 – head and prothorax, ventrolateral view; 5 – details of forebody, dorsolateral view. Scale bars = 0.5 mm.

FIGURES 6–8. Waidelotus hoffeinsorum gen. et sp. nov., holotype, No. 587-4 [CCHH]: 6 – details of venter; arrow indicates location of exposed genitalia; 7 – apical portion of genitalia; 8 – right antenna. Scale bars = 0.5 mm (Figs 6 and 8), and 0.25 mm (Fig. 7).