Cacomorphocerus incurvus, Sarker & Talukder, 2023

Sarker, Subir & Talukder, Saranika, 2023, Two new taxa of fossil Cantharidae from Baltic amber, Baltic Journal of Coleopterology 23 (2), pp. 233-239 : 233-239

† Cacomorphocerus incurvus sp. nov.

( Fig. 1 )

Holotype. Baltic amber, collection Fanti, access code BaA08RU (BaA = Baltic amber; 08 = sequential number; RU = Russia).

Type locality. Yantarny mine, Kaliningrad region, Russia.

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

Differential diagnosis. Compared to the new species described here, Cacomorphocerus cerambyx Schaufuss, 1892 shows a different pronotum, which is square, with narrower apical margin and a longitudinal impression on the disc ( Schaufuss 1892; Fanti & Kupryjanowicz 2018). Cacomorphocerus wiszniewskii Fanti & Kupryjanowicz, 2018 differs from the new species in the subrectangular pronotum, with sides slightly concave from base to the apical third, where a very small denticle is present, and in the less saucer-shaped antennomeres IV-VI ( Fanti & Kupryjanowicz 2018). Cacomorphocerus jantaricus ( Kuśka & Kania, 2010) shows antennomeres differently shaped and pronotum more rectangular, with sides slightly protruding laterally near the apical margin ( Kuśka & Kania 2010). The other

234 Description. Sex undefined, adult, robust, winged. Body length: about 7.3-7.5 mm (the specimen is folded), elytra 5-5.1 mm. Entirely blackish-dark brown.

Head elongated, rounded behind the eyes, covered with long setae and a shallow punctation. Eyes roundish, convex and prominent, inserted in the upper-lateral part of the head. Mandibles elongated, falciform. Maxillary palps 4-segmented; last palpomere securiform. Labial palps 3- segmented.

Antennae 12-segmented, short, reaching about the elytral half, strongly pubescent; scape short, stout, club-shaped; antennomere II very short, globular, about 2.7 times shorter than scape; antennomeres III–VII saucer-shaped and asymmetrically inflated; antennomere VIII strongly saucer-shaped and asymmetrically dilated with apical lobes, sturdier than previous ones; antennomere IX squared, thinner than previous one; antennomeres X–XII elongated, filiform, rather robust, X-XI slightly enlarged apically, last antennomere thinner and rounded at apex.

Pronotum transverse, about as wide as head; apical and basal margins straight; sides straight, without denticles; surface without impressions, covered with shallow granules and several setae. Scutellum triangular, with pointed apex which is rounded at apex.

Elytra long, covering and surpassing the last abdominal segment, parallel-sided and with rounded apex, wider than pronotum; surface smooth and pubescent. Hind wings transparent, slightly longer than elytra.

Metasternum wide, short, robust, rounded apically and pubescent. Sternites transverse and pubescent. Legs slender and short; coxae very large; trochanters elongated, rounded apically; femora cylindrical, straight, more robust than tibiae; tibiae cylindrical, pro- and mesotibiae very slightly longer than pro- and mesofemora, metatibiae longer than metafemora.

Tarsi 5-segmented, short; tarsomere I elongated, tarsomeres II and III triangular and shorter than I, tarsomere IV bilobed, tarsomere V elongated but not extremely thin and enlarged apically; claws simple with a very small and obtuse tooth at base.

Etymology. The specific epithet derives from the Latin adjective “ incurvus ” = curved, in reference to the pronotum and head bent.

Syninclusions. Enhydro and air bubbles, botanical fragments, stellate hairs.

Remarks. The oblong reddish yellow amber piece measures approximately 41x20x 10 mm. The inclusion is complete, with some folded parts and an open elytron showing the hind wing. Some parts of the body are slightly covered with white emulsion.

Figures

Fig. 1. Cacomorphocerus incurvussp. nov. in Baltic amber (code BaA08RU). A: Holotype, dorsal view, scale bar = 1.0 mm; B: Holotype, ventral view, scale bar = 1.0 mm; C: Holotype, detail of head (ventral view), scale bar = 0.2 mm.