Microscapha andrzeji, Bukejs, Andris & Alekseev, Vitalii I., 2015

Bukejs, Andris & Alekseev, Vitalii I., 2015, First record of Microscapha LeConte from Baltic amber with description of a new species and list of fossil Melandryidae (Coleoptera: Tenebrionoidea), Zootaxa 4012 (2), pp. 351-360 : 352-356

Microscapha andrzeji sp. nov.

( Figs 1–8 )

Type material. Holotype: Nr. “5057”, possible male. Complete beetle with partially exposed hind wings is included in small, transparent, polished, subrectangular amber piece (length about 11 mm, width 8 mm, and maximum thickness 2 mm), yellowish in color, without supplementary fixation. Mouthparts, pro- and mesothorax of specimen partly obscured by ‘milky’ opacity; abdomen largely covered by large gas vesicle. There are also three stellate Fagaceae trichomes, small gas vesicles, and small pieces of organic material in this examined amber piece.

Type strata. Baltic amber, Upper Eocene, Prussian Formation (Priabonian). Estimated age: 37.2–33.9 Ma.

Type locality. Baltic Sea coast, Gdańsk, Poland; Baltic amber, Upper Eocene, Prussian Formation.

Differential diagnosis. Microscapha andrzeji sp. nov. has unicolorous elytra (without distinct markings or fasciae), but differs from M. akitai Ishukawa & Sakai, 2004 , M. clavicornis LeConte, 1866 , M. pulicaria Champion, 1916 , M. minuta Champion, 1889 , M. bruchi Pic, 1930 M. africana Nikitsky & Below, 1982 , M. nigronotata Pic, 1931 , and M. yamoto Ishukawa & Sakai, 2004 in its more elongate body (2.19 times as long as wide), sublanceolate shape of medial depression within posterior two-thirds of metaventrite, longer metatibial spurs (longest spur about 0.89 times as long as metatarsomere 1), and coloration of legs and antennae. Microscapha andrzeji sp. nov. differs from M. isensis Sasaji, 1987 in its longer metatibial spurs, shape of terminal maxillary palpomere, proportions of antennomeres 9–11, and coloration of legs and antennae; from M. malayana Champion, 1916 in its more elongated body, indistinct punctation of pronotum, and coloration of body, legs and antennae; and from M. nepalensis Nikitsky, 1992 in its longer metatibial spurs, sublanceolate shape of medial depression in posterior two-thirds of metaventrite, and smaller body size.

Description. Body length 1.75 mm, maximal width 0.8 mm; oblong-oval in shape, 2.19 times as long as wide, moderately convex dorsally and ventrally; dark brown, with maxillary palpomere 4 and antennomeres 9–10 rufous; dorsally covered with short, dense, recumbent, pale setae, pubescence of ventral part and legs finer and less conspicuous.

Head inflexed downwards, frons with small and relatively dense punctures (but distinctly larger than elytral punctures); vertex smooth, shiny; genae impunctate, shagreened. Eyes large, slightly prominent; inner margin shallowly emarginated; with distinct facets larger than punctures on head. Distance between compound eyes equal to 0.4 times vertical diameter of one eye. Antennae 11-segmented, clavate, inserted between and close to inner margin of eyes; rather short, about 0.22 length of body, extending to base of elytra; scape and pedicel large, subcylindrical, subequal in length; antennomeres 3–7 very short and narrow (not distinctly visible in examined specimen), antennomere 3 much shorter and narrower than pedicel; antennomere 8 distinctly wider than antennomere 7; antennomeres 9–11 forming antennal club, and nearly as long as antennomeres 3–7 combined, antennomeres 9 and 10 equal in length, antennomere 11 about 1.2 times as long as antennomere 10. Maxillary palpi large, about 0.4 times as long as antenna, 4-segmented; palpomere 4 large, nearly as long as palpomeres 1–3 combined, distinctly dilated apically, about 2.25 times as long as wide, with obliquely truncated apex.

Pronotum transverse, 1.8 times as wide as long, without impressions, widest at base, gradually narrowed anteriad; with very fine, indistinct punctures, and dense transverse microreticulation; lateral margins narrowly bordered, almost straight, posterior margin distinctly bisinuate, anterior margin arcuate; anterior angles not pronounced, widely rounded, posterior angles roundly rectangular.

Scutellum small, distinct, triangular; with fine punctures. Elytra 1.8 times as long as wide, about 4.8 times as long as length of pronotum, widest in basal one-quarter of length, slightly and gradually narrowed from base to apex; with fine, relatively dense irregular punctures (more distinct in posterior half) and dense transverse microreticulation. Sutural striae well developed. Base of elytra nearly as wide as pronotal base. Hind wings preserved in type specimen, but cannot be observed in detail.

Prohypomera without distinct punctures, with dense microreticulation. Epipleura narrow, widest in basal onequater of length and then gradually narrowing posteriorly, not extending to elytral apex; shagreened. Mesocoxae oblong, transverse, about as wide as mesofemora, narrowly separated by subtriangular process of mesothorax. Metacoxae large, transverse, distinctly wider than metafemora, covered with fine punctures and shagreened. Metaventrite finely and relatively sparsely punctured (distinctly smaller and sparser than abdominal punctures); with sublanceolate medial depression in posterior two-thirds of length. Metepisternum triangular, narrowed posteriad; about 3.4 times as long as wide at anterior margin; covered with fine, dense punctures (similar to abdominal punctures) and shagreened.

Abdominal ventrites finely and densely punctured, distance between punctures equal to 0.5–1.5 times diameter of one puncture. Ventrites 1 and 2 large, equal in length; other ventrites not visible because of gas vesicle in surrounding amber.

Forelegs short, hind legs longer and most robust; tibiae and femora flattened. Mesofemora slightly dilated medially, about 4 times as long as wide; metafemora strongly widened, about 1.5 times as wide as mesofemora. Pro- and mesotibiae almost straight, with subparallel lateral sides; mesotibiae about 5.2 times as long as wide; metatibiae distinctly dilated apically, with oblique apex. Mesotibiae with small spur apically, about 0.31 times as long as mesotarsomere 1. Metatibiae with two long serrate spurs directed perpendicularly to each other, longest spur about 0.89 times as long as metatarsomere 1. Tarsal formula 5-5-4. Protarsus subequal in length to protibia, mesotarsus about 1.1 times as long as mesotibia, metatarsus about 2.2 times as long as metatibia. Protarsi weakly dilated. Penultimate tarsomere of pro- and mesotarsi slightly bilobed; penultimate tarsomere of metatarsi simple, subcylindrical. Length ratios of protarsomeres 1–5: 6-5-5-5-7; length ratios of mesotarsomeres 1–5: 16-6-5-5-7; length ratios of metatarsomeres 1–4: 15-5-4-5. Pretarsal claws simple, small, slightly curved.

Etymology. The epithet of the new species is an honorific dedicated to Andrzej Górski (Bielsko-Biała, Poland), the type specimen’s collector.

Note. The dilated protarsi indicate that the specimen is probably male.

Figures

FIGURES 1 – 2. Microscapha andrzeji sp. nov., holotype: 1 — habitus, dorsal view; 2 — habitus, ventral view.

FIGURES 3 – 4. Microscapha andrzeji sp. nov., holotype: 3 — details of fore-body, lateral view; 4 — details of fore-body, ventral view.

FIGURES 5 – 8. Microscapha andrzeji sp. nov., holotype: 5 — habitus, lateral view; 6 — medial depression of metaventrite; 7 — foreleg; 8 — metatibial spur.