Euroleptochromus tuberculatus Yin & Cai, 2018

Chen, Xin-Hui & Yin, Zi-Wei, 2023, New material of Euroleptochromus tuberculatus Yin & Cai (Coleoptera: Staphylinidae: Scydmaeninae) in Eocene Baltic amber, Zootaxa 5396 (1), pp. 131-134 : 132-133

Euroleptochromus tuberculatus Yin & Cai, 2018 ( Fig. 1 )

Euroleptochromus tuberculatus Yin & Cai, 2018: 147 .

Material examined. A complete female (determined by Micro-CT observation) entombed in a 12 mm × 8 mm × 2 mm suboval amber piece; deposited in SNUC.

Supplementary description. Habitus ( Fig. 1A, B ) moderately stout, body length 2.68 mm (actual size slightly larger due to oblique orientation of the specimen). Postgenae lacking extended projection, cuticle slightly raised to form tubercles, each postgena with two long bristles ( Fig. 1C , indicated by arrow heads). Submentum strongly transverse. Antennae covered with dense, suberect setae ( Fig. 1D ), much shorter than body, length 1.96 mm, lengths of antennomeres 1–11: 0.43 mm (1), 0.15 mm (2), 0.16 mm (3), 0.15 mm (4), 0.18 mm (5), 0.13 mm (6), 0.17 mm (7), 0.13 mm (8), 0.14 mm (9), 0.13 mm (10), 0.19 mm (11); relative lengths of antennomeres: 3.3: 1.2: 1.2: 1.2: 1.4: 1: 1.3: 1: 1: 1: 1.5. Pronotum in dorsal view suboval, broadest in middle, with rounded anterior and lateral margins; posterior margin arcuate; length along midline 0.73 mm. Elytra with dense, short pubescence; humeri markedly prominent. Metathoracic wings fully developed. Mesoventrite with narrow mesoventral intercoxal carina. Sternite III long, IV–VI distinctly shorter than III and subequal in length, VII slightly longer than VI, VIII large, longer than III.

Remarks. Two most important diagnostic features of this species, i.e., the lack of an elongate projection on each postgena ( Fig. 1C ), and five (3-1-1 placed) ventral spines ( Fig. 1E, F ) of the profemur, can be clearly observed in the new specimen, which excludes the possibility of morphological distortion of the holotype and supports E. tuberculatus as a distinct species.

The presence of well-developed hindwings in the female indicates flight capability, and possibly an active predatory behavior of this species.

Figures

FIGURE 1. New material of Euroleptochromus tuberculatus Yin & Cai, 2018 in Eocene Baltic amber. A, B, Habitus, ventrolateral (A) and dorsolateral (B). C, Head venter, showing maxillary palpi and postgenal bristles. D, Antenna. E, F, Profemur, showing 3-1-1 placed ventral spines. Scale bars = 1.0 mm in A, B; 0.2 mm in C–F.