Cacomorphocerus bentifabrici, Fanti & Damgaard, 2018

Fanti, Fabrizio & Damgaard, Anders Leth, 2018, Fossil soldier beetles from Baltic amber of the Anders Damgaard amber collection (Coleoptera Cantharidae), Baltic Journal of Coleopterology 18 (1), pp. 1-32 : 2-4

Cacomorphocerus bentifabrici n. sp.

( Fig. 1 ABC)

Holotype. Female, in Baltic amber, accession No. ALDC0057 /ALD. Ba.Can. 8

Type locality. Russia, Kaliningrad Region, Sambian Peninsula, amber quarry near Yantarny (previously known as Palmnicken).

Type horizon. Middle Eocene (Lutetian) (47.8- 41.2 MY) to Late Eocene (Priabonian) (37.8- 33.9 MY).

Differential diagnosis. The genus Cacomorphocerus is known for three species in Baltic amber: C. cerambyx Schaufuss, 1892 , C. jantaricus ( Kuśka & Kania, 2010) and C. wiszniewskii Fanti & Kupryjanowicz, 2018 and cited, at the generic level, also for the coeval Rovno amber ( Kazantsev & Perkovsky 2014). It is characterised by antennae 12-segmented with antennomeres III-IX dilated and saucer-shaped. This genus seems to be very uniform in the habitus and only the pronotal shape seems to be, in some cases, quite diagnostic. In fact, C. cerambyx shows a quadrate pronotum, with apical margin narrower, all angles roundish and surface with longitudinally impression, while C. jantaricus shows a rectangular pronotum, concave to the sides, with basal angles slightly protruding laterally and a small denticle near the apical angles. Furthermore, the surface is rough with deep punctation and two oblong tubercles ( Schaufuss 1892; Kuśka & Kania 2010). Finally, C. wiszniewskii shows a subrectangular pronotum with concave sides from after the base to the apical third and with a small denticle. The new species herein described, instead, has a pronotum slightly longer than wide, with apical margin and strongly rounded sides in the anterior part, and the surface is rough with two oblong thickenings in the middle. In addition, C. bentifabrici n. sp. is entirely dark brown, while C. jantaricus has black-brown elytra with yellow elongate spots on humeri and pale brown margin at apex ( Kuśka & Kania 2010), C. cerambyx is probably entirely black ( Schaufuss 1892) and C. wiszniewskii is dark brown with blackish sternites ( Fanti & Kupryjanowicz 2018).

Description. Adult, winged, robust and stocky habitus, female, entirely dark brown. Body length 8 mm (from front margin to elytral apex). Head rounded, very slightly narrower than pronotum and posteriorly strongly covered by pronotum, surface with shallow punctation. Eyes mediocre, roundish, strongly prominent. Maxillary palps 4-segmented with last palpomere securiform. Antennae short, few pubescent, reaching only the basal third of the elytra, 12-segmented, inserted in the inner anterior part at short distance from the eyes; scape elongated, stout, club-shaped; pedicel very short and cylindrical, about one-third as long as scape; antennomeres III-VI stout, slightly saucer-shaped and asymmetrically inflated; antennomere VII saucer-shaped; antennomere VIII strongly saucer-shaped and asymmetrically dilated; antennomere IX slightly narrower than antennomeres VII-VIII, subquadrate; antennomeres X-XII elongated and filiform. Pronotum slightly longer than wide; surface with setae and shallow punctation; angles roundish; lateral and particularly the apical margin strongly round and protruding to covering the head, two evident and parallel thickenings in the posterior half and close to the basal margin, which is flat. Scutellum triangular, elongated and with roundish apex. Elytra long, surpassing the last abdominal segments, parallel-sided, with rounded apex, as wide as the pronotum, covered with numerous and short setae and with rugose surface. Posterior wings covered by elytra. Sternum and abdomen pubescent (covered by milky emulsion); last ventrite wide and not triangular. Legs slender and fairly short; coxae massive; trochanters elongated; femora slightly enlarged and cylindrical with apex thin and completely fitted with short pubescence; tibiae with pubescence, cylindrical slightly longer than femora. Tarsi 5-segmented, short and massive; first tarsomere elongated; second about 1.5 times shorter than first tarsomere; third and fourth tarsomere triangular and shorter than second; fifth elongated and thin; claws simple, not well visible but probably with a delicate denticle at base.

Etymology. This new species is named in honour of the Danish musician Bent FabriciusBjerre, internationally known as Bent Fabric, in recognition of his career as a pianist and composer.

Syninclusions. Numerous wood remains (also botanical masses), stellate trichomes, and some air bubbles.

Remarks. The specimen is a female based on the relatively short antennae compared with other Cacomorphocerus species, and particularly for the last ventrite that is large and not triangular.

The piece of amber (that measures 37 x 28 x 9 mm) is not particularly transparent (lacquered). The inclusion is ventrally strongly covered by a white cotton-like cloud (emulsion, milky substance) making it impossible to get a clear vision of the ventral side of the beetle.

Figures

Fig. 1. ABC: Cacomorphocerus bentifabrici n. sp. in Baltic amber. A: Holotype, dorso-lateral view, bar = 1.0 mm; B: Holotype, detail of head and pronotum, bar = 300 μm; C: Drawing of pronotum, bar = 500 μm; D: Cacomorphocerus madseni n. sp. in Baltic amber. Drawing of pronotum, bar = 500 μm.