Micrambe sarnensis Lyubarsky et Perkovsky, 2010

Lyubarsky, G. Yu. & Perkovsky, E. E., 2021, New findings of Cryptophagidae (Coleoptera: Clavicornia) from Baltic amber in the unbiased collection of the Paleontological Institute of RAS, Russian Entomological Journal 30 (3), pp. 282-287 : 283

Micrambe sarnensis Lyubarsky et Perkovsky, 2010 Figs 1–4 .

MATERIAL. PIN 964 /1324, Baltic amber, Late Eocene. Sex: ♂. A new specimen of the recently described species Micrambe sarnensis was found. This allows for a more accurate description of the species, taking into account the variability .

RE-DESCRIPTION.Body broadly elongate ( Fig.1 ), slightly convex; head, pronotum, and elytra reddish brown. Elytra slightly convex, covered with almost appressed pubescence.

Head transverse, of normal size, with prominent, hemispherical, somewhat coarsely facetted eyes ( Fig. 4 ), strongly and sparsely punctured. Antennae 11-segmented, long, slen- der, with 3-segmented club, with club reaching beyond the base of pronotum, antennomeres 1–2 elongate, twice as long as wide, 3 th slender, elongate, twice as long as wide, joint 4 th subquadrate, antennomeres 5–6 1.5 times as long as wide, joint 7 th almost equal in length, antennomere 8 slightly transverse, 9 th and 10 th transverse, 10 th 1.2 times as long as wide, 11 th obliquely oval, antennomeres 9–11 equal in width.

Pronotum distinctly transverse, barely 1.8 times broader than long, moderately strongly and densely punctured (0.5–1 diameter apart), an individual puncture almost equal to facette diameter. Pronotum without sublateral line, somewhat convex, slightly rounded at sides, weakly crenulate. Sides finely margined, anterior edge weakly sinuate, posterior edge with broad median lobe, emarginated.

Anterior angles of pronotum with callosity, callosity occupying about one-third or one-fourth of side margin, with a small, elongate-oval patch of bare surface invisible from above; caudolateral corner acute angular, with tip. Lateral edge crenulated, with 7–9 small teeth. Posterior corners obtuse, base round, slightly sinuate, basal groove narrow.

Tarsal formula 5–5–4, claw simple, without tooth ( Figs 2–3 ). Last of tarsal joints longest.

Scutellum small, transverse. Elytra oval, punctuation confused, humeral corners rounded, shoulders a little broader than maximum breadth of pronotum, 1.4–1.5 times as long as wide and 2.8–2.9 times as long as thorax, moderately convex, with moderately strongly rounded sides and a narrowly round- ed apex, puncturation as strong as, yet more sparse than, that on pronotum. Epipleura reduced, present beyond level of posterior margin of 1 st ventrite. Ventrite 1 longer than remaining ventrites.

Length 1.6–2.2 mm.

REMARKS. Micrambe sarnensis was described from Rovno amber and now found in Baltic amber. The new specimen belongs to this species. The Micrambe species are very variable, the most important characters (in addition to the structure of the genitalia) are the structure of the antennae, the structure of the callosity, the relative length and width of the pronotum, and size and number of teeth on the lateral edge. This specimen slightly differs from the holotype of M. sarnensis , and is within the range of variability that can be observed, for example, in the very widespread M. abietis (Payk., 1798) , distributed throughout the Palaearctic.

The most noticeable differences between specimens:slight differences in the structure of antenna, antennomeres 1–2 elongate not transverse; callosity larger than in the holotype of M.sarnensis , occupying 1/3 of lateral edge. Size of body smaller, length of the holotype of M.sarnensis 2.2 mm.

Micrambe sarnensis is widespread in the late Eocene and in the Rovno and Baltic amber.

Figures

Figs 1–4. Photo of a new specimen of M. sarnensis from Baltic amber: 1 — dorsal view; 2 — lateral view; 3 — ventral view; 4 — head and pronotum, ventrolateral view. Рис. 1–4. ВнеШний вид M. sarnensis иЗ балтийского ЯнтарЯ: 1 — габитус, сверху; 2 — габитус, сбоку; 3 — габитус,сниЗу; 4 — голова и переднеспинка, сниЗу и сбоку.