Micrambe Thomson, 1863

Lyubarsky, Georgy., Legalov, Andrei A., Vasilenko, Dmitry V. & Perkovsky, Evgeny E., 2024, The first fossil of subgenus Neomicrambe (Coleoptera: Cryptophagidae: Micrambe) from Danish amber, Ecologica Montenegrina 72, pp. 227-234 : 228-229

Genus Micrambe Thomson, 1863

Subgenus Neomicrambe Otero & Pereira, 2019

Micrambe (Neomicrambe) tristis sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:180ACEE2-5EC4-466E-ACFE-9E59BEB38FCB

Figs. 1–3

Type material. Holotype. NHMD-153493, “G. V. Heningsen/ 16-5-1957 ”, Danish amber, late Eocene.

Etymology. From the Latin tristis , meaning mournful.

Differential diagnosis. Micrambe tristis sp. nov. differs from M. sarnensis Lyubarsky et Perkovsky, 2010 (Baltic and Rovno amber) by long sutural stria ( M. sarnensis : sutural stria absent); callosity occupying about one-fifth of pronotum side margin ( M. sarnensis : one-third or one-fourth of side margin); callosity visible from above ( M. sarnensis : callosity invisible from above); callosity without tip ( M. sarnensis : callosity with tip); pronotum narrowed basally, not narrower apically ( M. sarnensis : pronotum narrowed basally and apically); antennomere 3 short, not longer than 2, in 1.5 times longer than 4 ( M. sarnensis : antennomere 3 long, longer than 2, in 2 times longer than 4); antennomere 7 approximately equal length to antennomere 6 and 8 ( M. sarnensis : antennomere 7 longer than 6 and 8); antennomere 11 less than twice as long as 10 ( M. sarnensis : antennomere 11 twice as long as 10.

Description. Body length 1.8 mm, maximal body length 0.8 mm, pronotum length 0.45 mm, pronotum width 0.6 mm, elytra length 1.15 mm, elytra width 0.65 mm. 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. 1 ), head strongly and densely punctured (1 diameter apart). Antennae 11-segmented, long, slender, with 3-segmented club, club reaches beyond the base of pronotum, antennomeres 1–2 elongate, 1.5x as long as wide, antennomere 3 stout, 1.5x as long as wide, equal to 2 nd in length, antennomere 4 th subquadrate, antennomere 3 in 1.5x as long as 4 th length, antennomeres 5, 6, 8 subquadrate, antennomere 7 slightly longer, antennomere 8 slightly transverse, antennomeres 9 and 10 strongly transverse, antennomere 11 obliquely oval, antennomeres 11 slightly narrower than 10, 3 in 1.5x as long as 10 length ( Fig. 1 ).

Pronotum distinctly transverse, 0.75 times as long as wide, moderately strongly and densely punctured (1 diameter apart), an individual puncture almost equal to facet diameter. Pronotum without sublateral line, somewhat convex, weakly crenulate. Anterior angles of pronotum with callosity, callosity occupying about one-fifth of side margin, with small, elongate-oval patch of bare surface visible from above; caudolateral corner obtuseangular, without tip. Lateral edge almost not crenulated, with 5 very small teeth basally. Sides finely margined, narrowed posteriorly, not narrowed anteriorly, anterior edge weakly sinuate. Posterior corners obtuse, base round, slightly sinuate, basal groove narrow. Scutellum small, transverse. Elytra oval, punctuation confused ( Fig. 2 ), humeral corners rounded, shoulders a little broader than maximum breadth of pronotum, 0.8 times as long as wide and 2.8 times as long as thorax, moderately convex, with almost parallel sides and narrowly rounded apex, puncturation as strong as, yet more sparse than, that on pronotum. Sutural stria present. Epipleura reduced, present beyond level of posterior margin of 1st ventrite. Perhaps metathoracic wings present (as far as preservation allows us to determine). Ventrite 1 longer than remaining ventrites ( Fig. 3 ).

Remarks

Micrambe tristis sp. nov. is the first species of the genus reported from Danish amber and the second from European amber. Micrambe sarnensis was previously described from Rovno amber and reported from Baltic amber ( Lyubarsky & Perkovsky 2010, 2021).

Figures

Figure 1. Micrambe tristis sp. nov., dorsal view.

Figure 2. Micrambe tristis sp. nov., head and pronotum.

Figure 3. Micrambe tristis sp. nov., ventral view.