Pycnomerus simukovi, Alekseev, 2015

Alekseev, Vitalii I., 2015, New cylindrical bark and ironclad beetles (Coleoptera: Zopheridae) from Baltic amber, Baltic Journal of Coleopterology 15 (1), pp. 17-24 : 18-20

Pycnomerus simukovi sp. nov.

( Figs. 1-2 )

Material examined: Holotype Nr. 731-2 [ CCHH], sex unknown. The beetle is included in a polished piece of transparent amber, orange in color, thermally processed in an autoclave. The amber piece is embedded in a block of polyester resin with dimensions 9 x 9 x 3 mm. The syninclusions are represented by numerous fagaceous stellate hairs and by three phoretic mites (Acari: Acariformes) attached to the hind femora of the beetle.

Type strata: Baltic Amber. Eocene.

Type locality: Yantarny settlement [formerly Palmnicken], the Kaliningrad region, Russia .

Differential diagnosis: The new species can be assigned to Pycnomerus due to following morphological characters: tarsi 4-segmented; procoxal process expanded at apex; procoxal cavities externally closed, pro- and metacoxae widely separated; sparse antennal setation; glabrous parallel-sided body, eyes rounded and extending onto dorsal surface of the head; elytron with 10 striae; hypomeron lacking antennal cavities; expanded outer apical angle of protibia. Pycnomerus simukovi sp. nov. differs from the recent congeners in the following combination of characters: small body size (less than 3 mm); protibiae with outer apical angle expanded into a short tooth; 2- segmented antennal club; flattened pronotum without distinct median longitudinal depressions or sulci; pronotal punctuation having more or less uniform size; anterior and posterior angles of pronotum rounded and not produced; lateral margins of pronotum finely bordered; elytral intervals broader than striae.

Description: Body: TL = 2.9 mm, EW = 0.8 mm, elongate (TL/ EW = 3.6), shiny, glabrous, subdepressed, uniformly dark brown ( Fig. 1–2 ).

Head: twice wider than long; retracted into prothorax up to hind margins of the eyes; subantennal grooves absent; anterior clypeal margin rounded; forehead with a pair of pits. Head densely an d ir r egular ly pun ctur ed; punctures 2–3 times as large as ommatidia, separated by a space approximately 0.3–1 as wide as their diameter. Eyes entire, large, welldeveloped, finely faceted. Interfacetal setae not apparent (by x56 magnification). Antennae 11- segmented, moderately long (~ 0.5 mm), reaching the basal third of pronotum, stout, with a 2-segmented distinct club and a sparse setation.

Prothorax: PL = 0.75 mm, PW = 0.7 mm, subquadrate ( PL / PW =1.1); sides weakly

converging to base from just behind frontal angles; lateral margins smooth, very finely bordered; anterior angles narrowly rounded; posterior angles rounded, nearly obsolete; anterior margin straight, unmodified; posterior margin arcuate, finely grooved. Disc flattened, with a coarse dense simple almost uniformly oval punctuation, narrowly unpunctuated medially. The flattened area in the central part of the disc with two extremely shallow and poorly discernible longitudinal depressions. Hypomeron with dense, large and rounded pun ctur es. Pr oster n um mor e scar cely punctuated, especially medially; with a dense row of long and fine hairs distally.

Scutellum: rounded, oval, transverse (1.5 times wider than long), without punctures.

Elytra: EL = 1.9 mm, EW = 0.8 mm, parallel-sided; each elytron with 10 distinct longitudinal striae, without visible punctures; scutellary striole absent; intervals smooth, broader than striae; apices not flattened. Hind wings not apparent.

Abdomen: with five visible similarly articulated ventrites having relative lengths 20-17-17-14- 11. Surface without apparent (possibly absent) setation and with irregular punctuation; punctures slightly smaller and sparser medially, intervals between punctures 1–3 times wider than their diameter. Intermetacoxal apophysis (intercoxal process of the ventrite I) widely rounded.

Legs: procoxal cavities rounded and externally closed, meso- and metacoxal cavities closed. Metacoxae widely separated, separation greater than metacoxal length. Femora strongly thickened apically (clavate); protibiae with the outer angle expanded and produced into a short tooth. Tarsal formula 4-4-4. Length of apical protarsomere equal to combined length of protarsomeres I–III; length of apical meso- and metatarsomeres slightly shorter than combined length of the respective tarsomeres I–III; tarsal claws simple, large, equal in size, one-third as long as the apical tarsomere.

Derivatio nominis: Patronymic, the speciesgroup epithet is devoted to Mikhail A. Simukov (Kaliningrad, Russia), specialist in Baltic amber.

Figures

Fig. 1. Pycnomerus simukovi sp. nov. Habitus.: a) Dorsal view; b) Ventral view; c) Lateral view.

Fig. 2. Pycnomerus simukovi sp. nov. Dorsal habitus, reconstruction