Cacomorphocerus marki FANTI & M. G. PANKOWSKI, 2020

Fanti, Fabrizio & Pankowski, Maximilian G., 2020, A new Eocene soldier beetle (Cantharidae) of the genus † Cacomorphocerus Schaufuss, 1892 from Baltic amber, Zootaxa 4869 (3), pp. 437-443 : 438-440

Cacomorphocerus marki FANTI & M. G. PANKOWSKI sp. nov.

( Figs. 1–4 )

Description. Adult, winged, robust, entirely dark brown. Female, based on the last urite rounded and having short antennae. Body length: 7.1 mm; antennal length: about 3.6 mm; pronotum: about 1.35 mm long; elytral length: 5.35 mm.

Head prognathous, transverse, short, robust, slightly convex, covered posteriorly by the pronotum, with very shallow punctation and sparce erect setae. Eyes rounded, convex, prominent, inserted in lateral part of head, interocular distance about 3.0 times greater than eye diameter. Mandibles elongate, falciform, smooth, very large and triangular at base, thin and pointed apically. Maxillary palps 4-segmented, adorned with setae, palpomere I short and robust, almost globular, palpomere II elongate, palpomere III similar to II and slightly shorter, palpomere IV very elongated, thin, securiform, with rounded apex. Labial palps 3-segmented, last palpomere strongly securiform. Antennae 11-segmented, filiform, pubescent with erect setae, rather short and not reaching middle of the elytra, insertion rather far to upper margin of the eyes; scape robust especially at apex and club-shaped; pedicel about twothirds shorter than scape; antennomere III filiform, about 0.7 times longer than II; antennomeres IV-VII filiform, slightly longer than antennomere III; antennomeres VIII-X nearly equal in length and longer than previous ones; antennomere XI very elongated, cylindrical, thinner and slightly pointed at apex. Pronotum elongated, wider than the head, without shallow punctation and equipped with sparce and erected setae, surface flat, posterior margin wider than the slightly rounded anterior margin, each side narrower at the middle and with a rounded protuberance near the apex, posterior corners slightly rounded, anterior corners strongly rounded. Scutellar shield robust, triangular. Elytra elongate, slightly longer than the last abdominal segment, parallel-sided, completely smooth but adorned with erect setae, wider than the pronotum and the head, apexes rounded, suture and sides not bordered. Hind wings slightly infuscate and slightly longer than the elytra, almost completely covered by the elytra. Metasternum sub-rectangular, robust, pubescent; ventrites strongly transverse, pubescent. Last urite short, sinuous, with lobes. Legs slender and long, densely pubescent; coxae elongate and robust; trochanters elongate, vaguely triangular with rounded apex, slightly enlarged in the middle; femora elongate, robust, slightly enlarged and slightly curved; tibiae cylindrical, long, thin, with a spur on the side near the apex, protibiae very slightly shorter than the profemora, mesotibiae very slightly longer than the mesofemora, metatibiae longer than the metafemora; tarsi 5-segmented; tarsomere I elongate with protarsomere more robust than meso- and metatarsomere; tarsomere II shorter than tarsomere I; tarsomere III shorter than tarsomere II and vaguely triangular; tarsomere IV flat, bilobed with large lobes; tarsomere V slender, very elongated and curved; claws thin, elongate, pointed at apex and with an evident and obtuse denticle basally. Male unknown.

Etymology. Species named after Mark A. Pankowski, oldest brother of the second author who gave him a deep appreciation of nature by showing him how to find rare species everywhere from rivers to roadsides.

Holotype. Female, adult specimen included in a Baltic amber piece: Catalog number USNM PAL 770863 , in the Smithsonian’s National Museum of Natural History ( USNM) in Washington, DC in the USA.

Type locality. Quarry in Yantarny, Baltic Sea Coast, Sambian Peninsula, Kaliningrad Region, Russia.

Type strata. Baltic amber, Middle-Upper Eocene, Prussian Formation, also known as the “blue earth” formation.

Syninclusions. Botanical remains, stellate hairs, gas vesicles (air bubbles), mite (Acarina), and dipteran (Nematocera Culicomorpha).

Differential diagnosis. The species of Cacomorphocerus most commonly have 12 antennomeres, with the central antennomeres dilated or strongly saucer-shaped ( Schaufuss 1892; Kuśka & Kania 2010; Fanti & Damgaard 2018; Fanti & Kupryjanowicz 2018; Bukejs et al. 2019; Fanti & Pankowski 2019). In another species with 12 antennomeres, the “central antennomeres” are very slightly dilated or almost globular ( Parisi & Fanti 2020). Cacomorphocerus endecacerus Poinar & Fanti, 2019 from Baltic amber has 11 antennomeres, and it is easily distinguishable from C. marki sp. nov. by the former’s antennomeres II–VIII that are saucer-shaped or irregular instead of totally filiform as in C. marki sp. nov. ( Poinar & Fanti 2019). Also, Cacomorphocerus meridionalis Kazantsev & Perkovsky, 2020 from Rovno amber has 11 antennomeres with the “central antennomeres” strongly modified ( Kazantsev & Perkovsky 2020). Both C. endecacerus and C. meridionalis also have a very different pronotal shape (compared to C. marki sp. nov.) without a protuberance on each side ( Poinar & Fanti 2019; Kazantsev & Perkovsky 2020).

Remarks. The oval piece of amber (approximately 28 x 22 x 4 mm) is extremely transparent and allows an excellent view of the whole inclusion. There are no surface fractures or emulsion (a white cotton-like cloud sometimes found in Baltic amber). The specimen is complete and perfectly preserved in a relaxed and horizontal position. All structures including the mandibles, palps, and claws are clearly visible.

Figures

FIGURE 1. Cacomorphocerus marki sp. nov. in Baltic amber. A: Holotype, dorsal view, scale bar = 1.0 mm. B: Holotype, ventral view, scale bar = 1.0 mm.

FIGURE 2. Cacomorphocerus marki sp. nov. in Baltic amber. A: Holotype, detail of head and pronotum, scale bar = 0.5 mm. B: Holotype, detail of elytral apex, scale bar = 0.5 mm. C: Holotype, detail of head, pronotum and metasternum (ventral view), scale bar = 0.5 mm. D: Holotype, detail of urites, scale bar = 0.5 mm.

FIGURE 3. Cacomorphocerus marki sp. nov. in Baltic amber. A: Holotype, detail of antenna, dorsal view, scale bar = 0.5 mm. B: Holotype, detail of antenna, ventral view, scale bar = 0.5 mm. C: Holotype, detail of pro- and mesothoracic leg, scale bar = 0.5 mm. D: Holotype, detail of metathoracic leg, scale bar = 0.5 mm.

FIGURE 4. Cacomorphocerus marki sp. nov. in Baltic amber. A: Holotype, detail of head, mandibles and palps, ventral view, scale bar = 1.0 mm. B: Holotype, detail of metathoracic leg and last urites, ventral view, scale bar = 1.0 mm.