Thanatoplagia tamutisi Alekseev et Bukejs, 2024

ALEKSEEV, VITALII, MCKELLAR, RYAN C. & BUKEJS, ANDRIS, 2024, A revision and addition to Zopheridae (Coleoptera: Tenebrionoidea) in Baltic amber: possible connections between modern Holarctic distributions and Eocene ‘ amber forests’, Zootaxa 5536 (2), pp. 201-247 : 224-226

Thanatoplagia tamutisi Alekseev et Bukejs sp. nov.

( Figs 27–29 )

Type material. Holotype: No. ABAC 063 [ ACAB] (No. 3205 ex. coll. Marius Veta); “Holotype / Thanatoplagia tamutisi sp. nov. / Alekseev et Bukejs des. 2024” [red printed label]; adult, sex unknown. A complete beetle with partially exposed distal part of metathoracic wings included in a transparent, minute yellow amber piece with dimensions of 6× 3 mm and a maximum thickness of 3 mm, preserved without supplementary fixation. Syninclusions absent.

Type stratum. Baltic amber from Eocene amber-bearing Blaue Erde deposits; estimated age: middle–late Eocene (Standke 1998).

Type locality. Yantarny settlement (formerly Palmnicken ), Sambian (Samland) Peninsula, Kaliningrad Region, Russia.

Description. Measurements: total body length (including visible part of head) 2.9 mm, maximum body width (across elytra) 1.3 mm; head length 0.5 mm, head maximum width (across eyes) 0.6 mm; pronotal length 0.7 mm, maximum pronotal width 0.8 mm, basal pronotal width 0.8 mm; elytral length (along elytral suture, including scutellum) 1.8 mm.

Body subparallel-sided, elongate, about 2.2× as long as wide, moderately convex dorsally and weakly convex ventrally, unicolorous black (as preserved). Pubescence: head, pronotum and elytra sparsely covered with uniform, short, strongly curved, semierect setae that are not forming patches; ventral side of specimen with fine, inconspicuous, semierect setae.

Head prognathous, transverse; densely granulose dorsally, with granules rather large, about 2× as wide as diameter of one eye facet, and distance between granules distinctly smaller than diameter of one granule. Anterior margin of clypeus rounded.Compound eyes oval, convex, without interfacetal setation.Antennal insertions concealed dorsally; antennal grooves ventrad eye absent. Antennae stout, gradually widened towards apex, short, extending to middle of pronotum; 11-segmented, without clearly separated antennal club; sparsely covered with short, semierect setae, antennomeres 10 and 11 additionally with fine pubescence; densely punctate; scape wide, subcylindrical; pedicel cylindrical, nearly as long as wide, slightly narrower and shorter than scape; antennomere 3 subtrapezoidal, slightly dilated apically, nearly as large as pedicel; antennomeres 4–9 trapezoidal, strongly transverse, subequal in size and shape; antennomere 10 trapezoidal, dilated apically, strongly transverse, about 2.0× as wide as long, slightly wider than antennomere 9; antennomere 11 widely oval, transverse, 1.3× as wide as long, widely rounded apically, 1.1× as wide as antennomere 10. Terminal maxillary palpomere obliquely truncate, about 2.0× as long as penultimate palpomere.

Pronotum slightly transverse, 1.14× as wide as long, subparallel, weakly narrowed posteriad, widest at anterior margin; maximum pronotal width / basal pronotal width = 1.0; pronotal disc convex, with large, deep, oval impression medially and two shallow, oval, transverse impressions laterobasally; lateral sides narrowly explanate; pronotal surface densely covered with granules. Lateral margins almost straight, crenulate; anterior margin arcuate; posterior margin rounded. Anterior pronotal angles nearly rectangular, slightly rounded; posterior angles obtuse. Prothoracic notosternal suture complete. Hypomera and prosternum densely and coarsely granulate, distance between granules smaller than diameter of one granule. Intercoxal prosternal process elongate, extending beyond posterior margin of procoxae, with rounded apical margin, about 1.2× as wide as diameter of procoxa. Procoxal cavities open posteriorly.

Scutellar shield minute, oval, transverse.

Elytra almost parallel-sided within anterior two-thirds of their lengths, tapered at apex, about 1.4× as long as wide combined, convex, 2.6× longer than pronotum, distinctly wider than pronotal posterior margin. Humeral angles rounded. Elytra striate-punctate. Scutellary striole absent. Intervals convex. Epipleura well-developed, widest in basal half of length, slightly narrowed posteriad, reaching elytral apices, densely covered with granules. Mesocoxal cavities closed. Metaventrites with disc slightly convex, densely granulate, distinctly longer than abdominal ventrite 1; discrimen distinct in posterior half. Metanepisternum narrow, 6.3× longer than maximum width, with emarginate lateral margins. Metathoracic wings developed.

Legs rather short and robust, finely pubescent. Procoxa small, nearly rounded, separated by about 1.2× diameter of procoxa; mesocoxae hemispherical, separated by 0.7× diameter of mesocoxa; metacoxae oval, transverse, narrowly separated by about 0.5× longitudinal diameter of metacoxa. Femora elongate oval in shape, slightly dilated medially; femora and tibiae subequal in length. Tibiae straight, slightly dilated apically. Tarsal formula 4-4- 4; tarsomeres not dilated, with sparse, fine setation ventrally; tarsomere 4 longest, longer than metatarsomeres 1–3 combined, slightly curved. Claws simple, large, about 0.3× as long as tarsomere 4, robust.

Abdomen with five visible, similarly articulated ventrites, abdominal sutures distinct throughout length; densely covered with granules. Relative length ratios of ventrites 1–5 equal to 35:25:20:18:15. Abdominal ventrite 1 with triangular, apically rounded intercoxal process. Abdominal ventrite 5 with widely rounded posterior margin.

Differential diagnosis. As stated above, for the new genus.

Derivatio nominis. The epithet of this new species is patronymic. The species is named in honor of the Baltic coleopterist, leading researcher of Lithuanian beetles, and our colleague Dr. Vytautas Tamutis (Kaunas, Lithuania), for his numerous contributions to the study of entomofauna of Lithuania and beetles of the Baltic Sea region.

Figures

FIGURES 27–29. Thanatoplagia tamutisi gen. et sp. nov., holotype, No. ACAB 063 [ACAB]: 27—habitus, dorsal view; 28—habitus, ventral view; 29—habitus, right lateral view. Scale bars = 0.5 mm.