Rhagonycha (Rhagonycha) maryae, Fanti & Pankowski, 2018

Fanti, Fabrizio & Pankowski, Mary K., 2018, Three new species of soldier beetles from Baltic amber (Coleoptera, Cantharidae), Zootaxa 4455 (3), pp. 513-524 : 514-516

Rhagonycha (Rhagonycha) maryae FANTI & M. K. PANKOWSKI sp. nov.

( Fig. 1 )

Description. Adult, winged, slender and elongated. Female, defined on the basis of the large last sternite as wide as last tergite and apically sinuous and concave in the middle. Body length: 3.7 mm; elytra: 3.1 mm; antennae: approximately 2.8 mm. Entirely dark brown including legs and antennae. Head almost completely exposed, rounded, with thin and shallow punctation. Eyes rounded, convex, inserted laterally to the head, inter-ocular dorsal distance about 2.4 times greater than eye diameter. Mandibles not visible. Maxillary palps 4-segmented, unequal in length, with the last palpomere securiform. Labial palps 3-segmented, last segment securiform. Antennae filiform, 11-segmented and with all segments pubescent, relative short, surpassing half of elytra; antennomere I (scape) robust, elongated, club–shaped; antennomere II robust, short, 1.7 times shorter than scape; antennomeres III–V elongated, robust (particularly the third), slightly shorter than first article; antennomeres VI–IX filiform, subequal, thinner and around 0.1–0.2 times shorter than previous three articles; antennomere X filiform, approximately 0.3 times shorter than previous one; antennomere XI filiform as long as antennomeres VI–IX. Pronotum larger basally, trapezoidal, larger than head, posterior corners rounded, posterior margin strongly bordered, anterior margin and sides slightly bordered, sides concave at half length, surface irregular and equipped with short, thick pubescence. Scutellum subquadrate with apex truncate and straight. Elytra slender, parallel-sided, very elongated and completely covering and slightly surpassing the last abdominal segments, wider than pronotum, apex rounded, surface rugose and equipped with many short setae. Posterior wings present, almost completely covered by elytra. Metasternum dark brown, rounded posteriorly, equipped with setae; sternites short, transverse, wrinkled; last sternite wide, rounded and sinuous at apex with central concavity. Legs short and pubescent; coxae massive; trochanters rounded; femora slightly enlarged; tibiae thin, cylindrical, longer than femora. All tarsi 5-segmented; first segment elongated; second tarsomere elongated and longer than first tarsomere; third about 2.3 times shorter than second, straight at apex; fourth tarsomere bilobed at sides; fifth flat and elongated; claws apparently bifid at apex without denticles at base.

Etymology. Species named after Mary L. Pankowski, paternal grandmother of the second author, who provides immense love to her family, supports her community in numerous ways and inspires all with her indomitable spirit of optimism.

Holotype. Female, adult specimen included in Baltic amber, accession No. USNM PAL 712534 in the USNM.

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

Type strata. Baltic amber, Upper Eocene, Prussian Formation (Priabonian). Estimated age: 37.8–33.9 Mya. Syninclusions. Wood remains.

Differential diagnosis. The new species belongs to the genus Rhagonycha Eschscholtz, 1830 based on its bifid claws and for its anteriorly narrowed pronotum. Two species of the genus Rhagonycha have previously been described from inclusions in Baltic amber: R. kryshtofovichi ( Yablokov-Khnzorian, 1960) and R. sucinobaltica ( Poinar & Fanti, 2016) . Rhagonycha kryshtofovichi initially attributed to the genus Malchinus Kiesenwetter, 1863 was then transferred to Rhagonycha by Kazantsev (2013) based on the anteriorly narrowed pronotum, the fourth palpomere securiform and unmodified terminalia. In the genus Rhagonycha males and females possess the same pronotal shape. Thus, because the pronotal shape of R. maryae sp. nov. is different from R. kryshtofovichi and R. sucinobaltica , it can be distinguished as a new species. (It’s worth noting here that the specimen of R. maryae sp. nov. is a female because its last sternite is as wide as its last tergite, and it has an apical margin sinuous and concave in the middle. In the males of Rhagonycha , the last tergite is triangular and narrower than the last tergite.) R. kryshtofovichi is easily distinguishable from R. maryae sp. nov. based on its larger size (with a body length of 7 mm compared to 3.7 mm for R. maryae ), different pronotum and different length of the antennomeres (Yablokov- Khnzorian 1960). While the other known species R. sucinobaltica Poinar & Fanti, 2016 has similar dimensions (a body length of 3.5 mm), it possesses a different pronotum that is more curved at the sides and less bordered at the posterior margin ( Poinar & Fanti 2016). Rhagonycha maryae sp. nov. also differs from other inclusions in Baltic amber known at a generic level as well as specimens known from mold impression and compression fossils in various rocky sediments ( Fanti 2017a).

Remarks. The amber piece measures 19x19 x 4 mm and weighs 0.8 grams. It has a round shape and is rather flat.

Figures

FIGURE 1. Rhagonycha maryae sp. nov. in Baltic amber. A: Holotype, dorsal view, scale bar = 1.0 mm. B: Holotype, detail of head, pronotum and left antenna, scale bar = 0.5 mm. C: Holotype, ventral view, scale bar = 0.5 mm. D: Holotype, detail of leg and claws, scale bar = 0.2 mm.