Malthodes (Malthodes) josephi, 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 : 519-521

Malthodes (Malthodes) josephi FANTI & M. K. PANKOWSKI sp. nov.

( Figs. 4–6 )

Description. Adult, winged. Male, based on the last abdominal segments modified and the long antennae. Body length: 2.8 mm; elytra: 1.2 mm; antennae: 2.2 mm. Entirely dark brown including legs and antennae, without yellow spots on elytra. Head completely exposed, strongly rounded, larger than pronotum, equipped with shallow punctation. Eyes rounded, very large and prominent, inserted laterally to the head. Mandibles elongated, falciform, large at base and thin apically, concave on the internal side. Maxillary palps 4-segmented, unequal in length, with the terminal palpomere globular and distally pointed. Labial palps 3-segmented with the last segment globular and pointed. Antennae filiform, 11-segmented, long, surpassing the elytra, not reaching the last abdominal segments; antennomere I (scape) elongated, not club-shaped; antennomeres II–III filiform and approximately 1.4 times shorter than scape; antennomeres IV–X elongated, filiform, subequal in length, slightly longer than antennomeres II–III; antennomere XI thinner and longer than previous one, apically rounded; antennomeres with small setae. Pronotum large, transverse, surface undulating and with shallow punctation, posterior margin straight, anterior margin strongly bordered, sides sinuous, corners rounded. Scutellum triangular-shaped. Elytra wider than pronotum, short, slender, parallel-sided, reaching until the fifth abdominal segment, wide at base and narrower posteriorly to the humeral zone, apex rounded, surface pubescent. Posterior wings wide and long, dark, surpassing the elytra and the abdominal segments. Anterior and median legs very short, posterior legs long; coxae robust; trochanters elongated; femora enlarged; pro- and mesotibiae as long as pro- and mesofemora, metatibiae longer than metafemora, all the tibiae cylindrical and very thin. Tarsi 5-segmented; tarsomere I long and more of two times longer than second; tarsomere III slightly shorter than second; tarsomere IV bilobed; tarsomere V slender; claws simple. Penultimate tergite (tergite 9) elongated and slightly bent at sides; last tergite (tergite 10) short and wide with the sides bent, apically the margin is straight; last sternite (sternite 9) long and flat, large at base and curved after few millimeters, from which start two elongated and separated lobes with rounded apex; two wide and irregular with rounded apex urophysis, each inserted by the penultimate sternite (sternite 8) and located on both sides of the sternite 9. Sternal surface of abdomen punctate and with pubescence.

Etymology. Species named after Joseph M. Pankowski, paternal grandfather of the second author, who always puts his family first, is generous beyond words and who is a friend to all.

Holotype. Male, adult specimen included in Baltic amber, accession No. USNM PAL 712536 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 and air bubbles.

Differential diagnosis. Characters such as the globular and pointed last palpomere, the short elytra and the strongly modified last abdominal segments (both tergites and sternites) suggest that the new species belongs to the genus Malthodes . No other fossil of Malthodes shows the same features of the terminalia of the new species ( Fanti & Vitali 2017; Fanti & Michalski 2018), and no extant species of Central-North Europe and Alps is similar. Only the group of M. alpicola Kiesenwetter, 1852 ( M. alpicola , M. guttifer Kiesenwetter, 1852 , M. spretus Kiesenwetter, 1852 , M. bertolinii Fiori, 1905 ) might be seen as similar, although not from a strictly anatomical point of view, because of the last sternite (sternite 9) that is shaped as a wide, apically forked membrane ( Liberti 2011, 2015, 2016) and possessing a similar last tergite (tergite 10). However, these species are much bigger in size, and tendentially have a yellow spot (more or less evident) on each elytral apex. The group of M. minimus ( Linnaeus, 1758) is only vaguely similar, with the last tergite lobe-shaped and little developed, and the last sternite without median membrane. The important diagnostic characters of Malthodes are based on the male’s terminalia and habitus, as the morphology of the fossils is nearly identical to the living species. It is, however, interesting to note that, out of all the fossil species known, only M. perkovskyi Kazantsev from Rovno amber ( Kazantsev 2010) has the elytra with two yellow spots apically ( Förster 1891; Kuśka & Kupryjanowicz 2005; Kuśka & Kania 2010; Kazantsev & Perkovsky 2014; Fanti 2017b; Fanti & Vitali 2017; Fanti & Michalski 2018). These are indeed present, even if sometimes difficult to see, in many living species ( Fender 1951; Wittmer 1970; Liberti 2011, 2015, 2016, 2017).

Remarks. The amber piece measures 28x22 x 10 mm, is rectangularly shaped and weighs 2.8 grams. The amber is opaque yellow and there are scratches on the surface.

Figures

FIGURE 4. Malthodes josephi sp. nov. in Baltic amber. A: Holotype, lateral view, scale bar = 0.5 mm. B: Holotype, lateral view, scale bar = 0.1 mm. C: Holotype, detail of terminalia, scale bar = 0.1 mm. D: Holotype, detail of terminalia, scale bar = 0.2 mm.

FIGURE 5. Malthodes josephi sp. nov. in Baltic amber. Line drawing of the last abdominal segments, scale bar = 0.1 mm.

FIGURE 6. Malthodes josephi sp. nov. in Baltic amber. Arrows shows cuticular vesicles extruded from the abdominal segments.