Oracula campbelli, Nabozhenko & Perkovsky, 2023

Nabozhenko, Maxim V. & Perkovsky, Evgeny E., 2023, Oracula campbelli sp. n. - the first fossil darkling beetle (Coleoptera: Tenebrionidae Alleculinae) from the late Eocene Rovno amber (Ukraine), Zootaxa 5230 (2), pp. 245-250 : 246-248

Oracula campbelli sp. n.

( Fig. 1 )

Type material. Holotype (male): SIZK K-3503, Klesov , Rovno amber, late Eocene.

Syninclusions. SIZK K-3502 Ortheziidae , Chironomidae ; SIZK K-3503 Psychodidae , Chironomidae , Scelionidae , Theridiidae .

Description. Body light, slender, elongate, widest at elytral midlength. Legs probably yellow, because of femoral apices are clearly dark. Length 8.8 mm. Head wider, than anterior margin of pronotum. Eyes large, transverse diameter of one eye 1.3 times as long as interocular distance. Ocular index 26.Apical maxillary palpomere strongly securiform, with moderately oblique apical margin. Antennae not serrate, with strongly elongate and thin antennomeres (comparative length of antennae and the majority of antennomeres cannot be determined).

Prothorax. Pronotum weakly transverse (1.375 as wide as long), widest at base, looks bare, 1.3 times as wide as head at eye level. Lateral margins straight at least at basal third and weakly rounded and narrowed to apical margin at apical 2/3. Base of pronotum weakly bisinuate; posterior angles look weakly acute. Puncturation of pronotum dense and moderately coarse, puncture diameter subequal to distance between punctures.

Pterothorax. Scutellar shield with slightly rounded margins. Elytral base wider than pronotal base. Elytra 1.5 as wide as head and 1.13 times as wide (at maximal level of elytral basal part) as pronotum; surface looks bare (pubescence may not be visible under the white coating), at least without dense long erect pubescence; with deep striae, consisting of round deep punctures; puncture diameter slightly longer than interpuncture distance. Interstriae slightly convex.

Abdomen ( Fig. 1C ). Abdominal ventrites 1–3 beaded, 4 and 5 ones not beaded; ventrite 3 with oblique laterial margins; ventrite 5 widely rounded.

Legs ( Figs1B,C ). Femora thickened, strong, light, with dark apices.Tibiae without dense suberected pubescence. Pro- and mesotibiae clearly curved, metatibiae slightly curved. Protarsomeres 1–3 strongly widened, wider than mesotarsomeres 1–3. Preapical tarsomeres strongly widened, wider than other tarsomeres, strongly lobed. Tarsal claws large and hollow ( Fig. 1B , inset); anterior claws with 19 (9+10) teeth on both sides

Etymology. The species is named in memory of Dr. Milton J. Campbell (December 19, 1936 — August 6, 2022), the famous specialist on comb-clawed beetles of the New World.

Comparative diagnosis. The new species belongs to the subgenus Duocula Novák, 2019 in the presence of teeth on both sides of hollow claw.

The new species is most similar externally to O. amica Novák, 2019 from Nepal in the presence of dark femoral apices with more or less distinct colour borders, straight lateral margins of pronotum at least at basal third and the absence of erected or suberected long dense pubescence on elytra and tibiae. The new species differs from O. amica by the less dense puncturation of the pronotum (puncture diameter longer than interpuncture distance in O. amica ) and the shape of the pronotum with pointed at apex basal angles (narrowly rounded apices in O. amica ). The new species has darkened part only at the most distal part of femora, while femora of O. amica are darkened at the distal quarter. Oracula campbelli sp. n. differs from all species of the genus by the presence of 19 teeth on male claws (more than 30 in all extant representatives; more than 40 in Duocula)

Figures

FIGURE 1. Oracula campbelli sp. n. from Rovno amber, habitus: A—dorsal view; B—lateral view (arrow in the inset shows the dark area of hollow claw); C—ventral view.