Malthodes (Malthodes) gedanicus, Fanti & Sontag, 2019

Fanti, Fabrizio & Sontag, Elżbieta, 2019, A new fossil soldier beetle (Coleoptera: Cantharidae: Malthininae) from Baltic amber, Zootaxa 4629 (4), pp. 583-588 : 584-585

Malthodes (Malthodes) gedanicus sp. nov.

( Figs. 1–2 )

Description. Adult, winged, male defined on the basis of the last urites strongly modified. Body slender, length: 2.4 mm; pronotum: 0.3 mm; elytra: 1.0 mm. Entirely dark brown-blackish without yellow spots on elytra. Head exposed, small, rounded, covered by stout and short setae and small and impressed punctation on the clypeus. Eyes very large, prominent, convex, rounded, inserted in the lateral-upper part of the head. Mandibles falciform, elongated, robust at the base and thin apically. Maxillary palpi 4-segmented, first palpomere short, second palpomere triangular, third elongated, last palpomere globular and distally pointed. Labial palpi 3-segmented, last palpomere globular and distally pointed. Antennae filiform, 11-segmented, slightly surpassing the elytra; antennomere I elongated, club-shaped; antennomere II about 1.9 times shorter than antennomere I; antennomere III slightly shorter than antennomere II; antennomeres IV–VI subequal in length, longer than antennomere II; antennomeres VII–X subequal in length, shorter than previous; antennomere XI elongated, rounded at apex; all antennomeres covered by long setae. Pronotum strongly transverse, wider than head, surface slightly undulate and scarcely punctate with short setae, sides straight, posterior and anterior margin slightly bordered. Elytra short, reaching the sixth abdominal segment (tergite), slightly wider than pronotum, covered with erected setae, parallel-sided, rounded at apex. Hind wings infuscate, surpassing the elytra. Legs short, pubescent; coxae stout; trochanters elongated with rounded apex; femora enlarged; tibiae cylindrical and thin, protibiae shorter than profemora, mesotibiae as long as mesofemora, metatibiae longer than metafemora. Tarsi 5-segmented, pubescent; tarsomere I thin, elongate; tarsomere II shorter than tarsomere I; tarsomere III shorter than second; tarsomere IV bilobed; tarsomere V elongate, flat, slender; claws simple. Metasternum subquadrate, covered with sparse setae. Sternites transverse and pubescent. Penultimate tergite (tg9) wide, transverse, with the sides slightly folded; last tergite (tg10) very elongated, basally large and subsequently thinner and flat, with apex spatuliform; last sternite (st9) elongate, covered with long and fitted setae, slightly curved, apically divided into two long and flat squarish lobes with three tips of which the central is longest. Aedeagus only partially visible, with roundish tegmen sternal shield (sternal lobe) and two elongated parts (probably the laterophysis). Female unknown.

Etymology. The specific epithet refers to Gedania, the Latin name of the city of Gdańsk ( Poland), which is the type locality (its gulf), and city where the holotype is preserved.

Holotype. Male , inclusion in Baltic amber, housed at the Museum of Amber Inclusions, University of Gdańsk, Poland, under accession No. MAIG 5973 (IAA Certificate No. 14953).

Type locality. Gulf of Gdańsk, Russia, Kaliningrad region, Sambian Peninsula, Yantarny mine.

Type horizon. Middle Eocene (Lutetian) (47.8–41.2 Ma) to late Eocene (Priabonian) (37.8–33.9 Ma).

Syninclusions. Stellate hair, botanical fragments, air bubbles (of which one big) and inorganic big masses. No other animals.

Systematic placement. The last maxillary palpomere globular and pointed distally, clearly make this specimen belonging to the subfamily Malthininae . The rounded head behind eyes, the antennae filiform and the strongly modified terminalia, place the new, extinct species in the genus Malthodes .

Differential diagnosis. No other fossils of Malthodes has this combinations of characters (in particular the terminalia) shown by M. gedanicus sp. nov. The shape of the last abdominal segments, makes difficult to identify phylogenetic relationships of this fossil with extant species, both European and North American ( Fender 1951). European Malthodes trifurcatus Kiesenwetter, 1852 is distantly similar. This species has the last sternite with three tips and also much larger body: 3 or 3.8–6.1 mm ( Porta 1929; Liberti 2011, 2015). M. trifurcatus also has a very different last tergite which is not spatuliform apically and more curved.

Remarks. The original amber piece measured 35x20 x 7 mm and weighted 3.1 grams (after preparation, it has the shape of polyhedron measuring approximately 7x8x 5 mm and weight of 0.3 grams). The amber has an excellent transparency that allows an unobstructed observation of the inclusion. The specimen is complete except for the apical antennomere of the left antenna.

Figures

FIGURE 1. Malthodes (Malthodes) gedanicus sp. nov. in Baltic amber, holotype. A: dorsal view. B: ventral view. Scale bars = 0.5 mm.

FIGURE 2. Malthodes (Malthodes) gedanicus sp. nov. in Baltic amber, holotype. A: detail of the last abdominal segments, lateral view. B: detail of the last abdominal segments, ventral view. C: reconstruction of the last adbominal segments. D: detail of head. Scale bars = 0.1 mm (A–C), 0.2 mm (D).