Aneurops daugpilensis, Bukejs, Andris & Alekseev, Vitalii I., 2015

Bukejs, Andris & Alekseev, Vitalii I., 2015, Description of the second fossil Baltic amber species of Monotomidae (Coleoptera: Cucujoidea), Zootaxa 3946 (3), pp. 445-450 : 446-449

Aneurops daugpilensis sp. nov.

( Figs 1–4 )

Type material. Holotype: Nr. “040” [white printed label], “ Holotype / Aneurops daugpilensis sp. nov. / des. Bukejs A. & Alekseev V.” [red printed label]; sex male. A complete beetle is embedded in a small suboval amber piece (length 8 mm, width 6 mm, weight 0.2 grams); other animals and plant syninclusions are absent. The amber was not subjected to any fixation.

Type strata. Baltic amber, Upper Eocene, Prussian Formation (Priabonian). Estimated age: 37.2–33.9 Ma.

Type locality. Yantarny settlement [formerly Palmnicken], the Sambian [Samland] peninsula, the Kaliningrad region, Russia.

Etymology. The species name is derived from Daugpiļs, the Latgalian name of the Latvian city Daugavpils ( German: Dünaburg, Russian: Dvinsk), the birthplace of the first author.

Differential diagnosis. Aneurops daugpilensis sp. nov. is similar to two extant members of genus, but differs from A. convergens ( Sharp, 1900) in having larger punctation on pronotum, head and abdomen (especially ventrite 5); less distinct impunctate median zone on pronotal disc; shorter and sparser setation of median plaque on ventrite 1; shorter elytra; and less convex eyes. The new species differs from A. championi Sharp, 1900 in having larger punctation on pronotum and abdomen; shorter and sparser setation of median plaque on ventrite 1; and smaller body size.

The newly described species could be compared with contemporary Europs insterburgensis Alekseev, 2014 from Baltic amber, but is clearly distinguished by the presence of a median plaque on ventrite 1, larger body size (2.1 mm in E. insterburgensis ), distinctly sparser punctation of forebody (in E. insterburgensis distance between pronotal punctures less than puncture diameter), smaller eyes, and larger temples.

Description. Body length 2.5 mm, WH = 0.65 mm, PL = 0.65 mm, PW = 0.6 mm, LE = 1.1 mm, WE = 0.65 mm; elongate, weakly convex dorsally and ventrally; unicolorous dark brown, dull; glabrous, except setae on ventrite 1, and very fine, short, erect setae on elytra.

Head prognathous, wide (WH/WP = 1.08); with small and dense punctures (punctures on neck distinctly sparser and finer) dorsally, and with moderately large and dense punctures ventrally; shagreened. Eyes moderately convex, with small facets. Frons with subtriangular depression. Temples well developed, with length of about 0.7 times longitudinal diameter of eye. Neck distinct. Antennae short, extending to anterior one-fourth of pronotum; 11-segmented with 3-segmented club (appearing 2-segmented because antennomeres 10 and 11 fused); scape large, slightly wider and longer than pedicel; antennomere 2 suboval, 1.4 times wider than antennomere 3; antennomeres 3–8 nearly equal in length and width; antennomere 9 transverse, nearly as wide as antennomere 10. Antennal grooves absent.

Pronotum weakly elongate (LP/WP = 1.08), maximal width in anterior one-fourth, slightly narrowed anteriad and posteriad; pronotal disc weakly convex; anterior and posterior margins straight; lateral margins nearly parallel, crenulate; anterior angles rounded, not protruding; posterior angles rounded. Pronotal punctures irregular (punctures on pronotal disc forming weakly regular rows), moderately large (punctures on pronotal disc distinctly larger than elytral punctures in basal half), and moderately dense (punctures on disc distinctly sparser than punctures at sides); distance between punctures varying from 1 to 4 times diameter of one puncture; interspaces shagreened. Smooth, longitudinal, median area narrow (about as wide as diameter of 2–4 punctures). Scutellum nearly round, with fine, sparse punctation, and without setae. Prothorax weakly convex, with small and very sparse punctures, shagreened; with transverse rugosity medially. Protrochantins partially exposed. Procoxae nearly round; procoxal cavities closed posteriorly. Prosternal process large, trapezoidal, distinctly widened posteriorly; covered with small, sparse punctures; posterior margin straight, length nearly 1.7 times transverse diameter of procoxa.

Elytra relatively short (LE/LP = 1.7), with nearly parallel sides, widest at middle; truncate apically, exposing last two abdominal tergites; base weakly concave, distinctly wider than base of pronotum. Elytral punctures round, small (punctures in basal one-third distinctly larger than at apex), dense, arranged in regular striae; with fine, very short erect setae (distinctly visible only in basal one-third); distance between punctures equal to 2–3 times diameter of one puncture; striae distinct throughout entire length of elytron; intervals flat, shagreened. Inflexed part of elytron with three striae of punctures. Two visible tergites covered with fine and dense punctures; with widely rounded apex. Hind wings present. Meso- and metaventrites with distinctly denser and larger punctation than prosternum; shagreened between punctures. Posterior margin of metaventrite straight with narrow excision medially (between metacoxae). Mesocoxae oval, distance between them nearly equal to 0.5 times transverse diameter of mesocoxa. Metacoxae elongate-oval.

Abdomen with five ventrites, covered with small and sparse punctures (ventrite 5 with distinctly larger and denser punctation, and distance between punctures distinctly smaller than diameter of puncture) and shagreened. Ventrite 1 in basal half with median, oval plaque more punctured than adjacent area and bearing proportionally long and distinct setae. Coxal beads on ventrite 1 triangularly produced. Ventrite 1 elongate, longest, distinctly longer than ventrites 2–4 combined. Ventrites 2–4 short, equal in length. Ventrite 5 simple, with widely rounded posterior margin. Relative length ratios of ventrites 1–5 equal to 21:4:4:4:13. Abdominal intercoxal process triangular, rounded anteriorly.

Legs relatively short and robust. Femur spindle-shaped, distinctly widened medially. Tibia gradually widened apically; about 0.75 times length of femur. Protarsus with long and dense pubescence ventrally; meso- and metatarsus with comparatively shorter and sparser pubescence ventrally. Penultimate tarsomere not bilobed; ultimate tarsomere distinctly longer than all previous tarsomeres combined. Claws simple, long and thin.

Note. The sex of the specimen is male based on the presence of the following character states which are peculiar to males in extant species of Aneurops : ventrite 1 with median, oval plaque; elytra truncate apically exposing two tergites.

Figures

FIGURES 1 – 2. Aneurops daugpilensis sp. nov., holotype, habitus: 1 — dorsal view; 2 — ventral view.

FIGURES 3 – 4. Aneurops daugpilensis sp. nov., holotype: 3 — details of prothorax; 4 — details of metathorax and ventrite 1, white arrow shows median plaque.