Symphora pollocki, Alekseev & Bukejs, 2021

Alekseev, Vitalii Igorevich & Bukejs, Andris, 2021, Fossil Melandryidae (Coleoptera: Tenebrionoidea) from Eocene Baltic amber of the Sambian peninsula: new genus, six new species, new records and key to described taxa, Zootaxa 4965 (1), pp. 142-166 : 154-156

Symphora pollocki sp. nov.

( Fig. 6 , 8D )

Type material. Holotype: No 6713 [ MAIG] (ex. coll. Jonas Damzen JDC 9407), “ Holotype / Symphora / pollocki sp. nov. / Alekseev et Bukejs des. 2021” [red printed label]; adult, male. A complete beetle with partially exposed aedeagus included in a transparent, small, yellow amber piece with approximate dimensions of 10 mm × 5 mm and a maximum thickness of 4 mm; preserved without supplementary fixation. Organic syninclusions: one stellate fagacean trichome.

Type stratum. Baltic amber from Eocene amber-bearing blue Earth layers, mostly Bartonian age is interpreted for the extinct central European resin-producing forests ( Bukejs et al. 2019).

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

Description. Measurements: body length 2.1 mm; pronotum length 0.4 mm, pronotum maximum width 0.5 mm; elytra length 1.4 mm; elytra maximum width 0.8 mm. Body oblong, subparallel, slightly convex dorsally and ventrally; dark brown, unicolorous; distinctly punctate and pubescent; pubescence semierect dorsally and almost recumbent ventrally, with additional very sparse, erect setae on elytra.

Head prognathous, visible in dorsal view, sparsely covered with shallow punctuation; frons and vertex slightly convex. Fronto-clypeal suture distinctly impressed, arcuate. Compound eyes small, slightly emarginate at antennal base, prominent, rounded, almost hemispherical; facets distinct and fine, without intrafacetal setae; interocular distance at upper margin of eyes about 1.7× as diameter of one eye. Clypeus with small angulate projection. Maxillary palpi about 0.3× as long as antenna; with 4 palpomeres: palpomeres 1–3 small, subequal in size, nearly as long as wide, palpomere 4 largest and widest, subtrianqular, with slightly rounded angles. Antennal insertions concealed from above. Antennae filiform, with 11 antennomeres, inserted close to anterior margin of eyes, pubescent, reaching posteriorly to one-fourth of elytra; scape subcylindrical, about 1.4× longer than wide; pedicel cylindrical, narrower than scape and wider than antennomere 3; antennomeres 3–10 gradually widened to antennal apex; antennomeres 3–6 conical, elongate, slightly dilated apically; antennomeres 7–10 trapezoidal, elongate, distinctly dilated apically; antennomere 11 spindle-shaped with pointed apex. Ratio of relative lengths of antennomeres 1–11 = 10:?7:?8:8:8: 7:7:7:10:10:10.

Pronotum transverse, 1.3× wider than long, widest at base; densely covered with rough punctuation. Pronotal disc evenly convex, with two small, distinct, rounded impressions basally. Anterior pronotal margin weakly convex (in dorsal view); posterior margin narrower than elytral anterior margin, weakly bisinuate, finely margined; lateral margins gradually narrowed anteriad. Lateral pronotal carina present in form of short carination laterally discernible at posterior pronotal angles only. Anterior pronotal angles rounded; posterior angles almost right-angled. Prohypomera weakly convex, sparsely covered with distinct punctuation. Procoxal cavities without fissure (trochantin not visible). Scutellar shield small, oval, strongly transverse, about 2.3× wider than long.

Elytra elongate, about 1.8× longer than wide, almost parallel-sided in anterior two-third, gradually narrowed in posterior one-third, about 3.5× longer than pronotum; elytral apices rounded separately; elytral punctuation irregular, distance between punctures 0.5-2.0× as one puncture diameter, punctuation denser and coarser anteriorly and medially. Epipleura narrow, widest at humeri and gradually narrowed posteriad, reaching posterior margin of abdominal ventrite 1. Metaventrite convex, with sparse punctuation, distance between punctures larger to diameter of one puncture. Metepisternum rather wide, slightly not dilated anteriorly, with subparallel lateral sides, about 4× longer than maximum wide.

Legs moderately long. Procoxae contiguous, conical; mesocoxae roundish, apparently separated; metacoxae elongate oval, transverse, apparently narrowly separated. Femora weakly flattened. Tibiae subcylindrical, almost straight, slightly dilated apically, subequal in length to femora; paired metatibial spurs short, equal in size, about 0.6× as long as metatibial width at apex. Tarsi long and slender; tarsal formula 5-5-4; penultimate tarsomere of all legs bilobed; tarsomeres 1–4 of fore and middle legs slightly dilated (sexually dimorphic character showing that specimen is male); metatarsus nearly as long as metatibia, metatarsomere 1 about 0.5× as long as metatibia length; ratio of relative lengths of metatarsomeres 1–4 = 17:7:6:4. Pretarsal claws simple, falcate, symmetrical.

Abdomen with five visible ventrites of subequal length, sparsely punctate, distance between punctures distinctly larger than one puncture diameter; ventrite 5 with rounded apical margin.

Apical portion of aedeagus as in Fig. 8D .

Etymology. The epithet of this new species is patronymic. The species is named in honor of a coleopterist and specialist in Tenebrionoidea, our colleague Dr. Darren A. Pollock (Portales, USA) for his numerous contributions to the study of Melandryidae , Mycteridae , Pythidae , Salpingidae , Tetratomidae , Trictenotomidae , and other beetles.

Differential diagnosis. The extant representatives of Symphora are rather uniform and can be distinguished by minute details of body punctuation and coloration. Dark and unicolorous Symphora pollocki sp. nov. differs from extant Holarctic species in distinctly lesser body size (in contrast to S. flavicollis , S. rugosa and S. atra , which are longer than 3.8 mm). This new species from Baltic amber differs from S. brunnea in transverse scutellar shield (quadrate in S. brunnea ) and wider interocular distance. Additionally, S. pollocki sp. nov. differs from S. atra in antennomeres 10 and 11 of equal length.

Figures

FIGURE 6. Symphora pollocki sp. nov., holotype, No 6713 [MAIG], habitus:A—dorsal view; B—left lateral view; C—ventral view. Scale bars represent 1.0 mm.

FIGURE 8. Apical portion of aedeagus in ventral view: A—Electroxylita chronographica gen. et sp. nov.; B—Phloiotrya inmarinata sp. nov.; C—Madelinia capillata sp. nov.; D—Symphora pollocki sp. nov. Not reproduced to the same scale.