Baltodascillus, Kundrata & Gimmel & Packova & Bukejs & Blank, 2021

Kundrata, Robin, Gimmel, Matthew L., Packova, Gabriela, Bukejs, Andris & Blank, Stephan M., 2021, A new enigmatic lineage of Dascillidae (Coleoptera: Elateriformia) from Eocene Baltic amber described using X-ray microtomography, with notes on Karumiinae morphology and classification, Fossil Record 24 (1), pp. 141-149 : 142-143

Genus Baltodascillus gen. nov.

Type species Baltodascillus serraticornis sp. nov., here designated urn:lsid:zoobank.org:act:A2B037D4-8951-4BE2-8263-4891CCD03E3B ; Figs. 1–4 , Video supplements 1–4

Etymology

Derived from the words “Baltic” (referring to Baltic amber) and “ Dascillus ” (a genus name in Dascillidae ). Gender: masculine.

Diagnosis

Baltodascillus gen. nov. can be recognized among other genera of Dascillidae by the reduced mandibles ( Figs. 2a , 3d ). Additionally, the following combination of characters serves to distinguish it from all other genera: strongly serrate antennae, a fusiform terminal maxillary palpomere, large eyes, pronotum widest posteriorly and with a strongly developed lateral carina, lack of a developed prosternal process, complete elytra, confused elytral punctation, a weakly developed elytral epipleuron, and abdomen with five ventrites ( Figs. 1– 4 ).

Description

Body ( Fig. 1 ) narrowly elongate. Eyes large, strongly protuberant. Frontoclypeal suture distinctly impressed. Labrum wider than long, distinctly sclerotized, anteriorly slightly concave. Antenna ( Figs. 1–3 ) serrate, almost reaching middle of elytra; antennomeres 3–10 with prominent, acute serrations; terminal antennomere simple, elongate, apically rounded. Mandible ( Figs. 2a , 3d ) considerably reduced, very short, subtriangular, without teeth, apically narrowly rounded. Maxillary and labial palpi ( Figs. 2c, d ; 3 ; 4a, b ) each with terminal palpomere fusiform, apically flattened and narrowly rounded.

Pronotum ( Figs. 2b, c ; 3a, d ) transverse, widest near posterior angles; sides weakly arcuate; lateral carinae distinct, complete; posterior angles weakly acute; posterior edge weakly crenulate. Hypomeron with postcoxal process obtuse. Prosternal process ( Figs. 3b ; 4b, c ) not developed, forming short right-angled denticle. Elytra ( Figs. 1a ; 2a, b ) elongate, lateral edges more or less straight, widest at apical third, then gradually narrowed towards apex; elytral surface without costae or striae; elytral punctures irregular, only partially in weakly defined rows; elytral epipleuron narrow and oblique behind humeral area. Leg ( Figs. 1b ; 2d ; 4a, b ) with tibia about as long as femur in fore- and midlegs, and slightly longer than femur in hind legs; tibial spurs paired, approximately equal in length, serrate. Tarsomeres ( Figs. 2e, f ; 4f, g ) 1–4 each with membranous ventral lobe; lobes gradually larger from tarsomere 1 to tarsomere 4, those on tarsomeres 2–4 strongly bilobed.

Abdomen ( Figs. 1b ; 4d, e ) with five ventrites; ventrites 1–4 gradually shorter towards apex; ventrite 1 without delimited hind coxal cavities, and with intercoxal process indistinct; ventrite 5 slightly longer than 4, triangular, narrowly rounded apically.

Composition and distribution

Figures

Figure 1. Baltodascillus serraticornis gen. et sp. nov., holotype: (a) habitus, dorso-frontal view; (b) habitus, ventro-lateral view. Scale bar = 2.0 mm.

Figure 2. Baltodascillus serraticornis gen. et sp. nov., holotype: (a) habitus, lateral view; (b) pronotum and scutellar shield, dorsal view; (c) head and pronotum, dorsal view; (d) head and thorax, ventral view; (e) tarsus, ventro-lateral view; (f) tarsus, ventral view. Scale bars = 1.0 mm (a–d), 0.3 mm (e, f).

Figure 3. Baltodascillus serraticornis gen. et sp. nov., holotype, Xray micro-CT renderings:(a) head and thorax, dorsal view; (b) head and thorax, ventral view; (c) head and thorax, right lateral view; (d) head and thorax, left lateral view. Scale bars = 1.0 mm.

Figure 4. Baltodascillus serraticornis gen. et sp. nov., holotype, X-ray micro-CT renderings: (a) head, frontal view; (b) head and thorax, fronto-ventral view; (c) pro- and mesothorax, ventral view; (d) abdomen (ventrites 2–5), lateral view; (e) abdomen (ventrites 2–5), ventral view; (f) tarsus, ventral view; (g) tarsus, dorsal view. Scale bars = 1.0 mm.