Cretobrachygluta laurasiensis, Yin & Kurbatov & Cuccodoro & Cai, 2019

Yin, Zi-Wei, Kurbatov, Sergey A., Cuccodoro, Giulio & Cai, Chen-Yang, 2019, Cretobrachygluta gen. nov., the first and oldest Brachyglutini in mid-Cretaceous amber from Myanmar (Coleoptera: Staphylinidae: Pselaphinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 59 (1), pp. 101-106 : 103-105

† Cretobrachygluta laurasiensis sp. nov.

Type material. HOLOTYPE (SNUC-Paleo-0076): a well-preserved male in an approximately 7.2×5.0 mm clear,yellowish amber piece; upper Albian to lower Cenomanian, Hukawng Valley, northern Myanmar ( SNUC).

Diagnosis of male. As for the genus (vide supra), plus the following: body length 1.85 mm; mesotrochanters protuberant at ventral margin; mesotibiae with small, triangular preapical spur.

Description. Habitus ( Fig. 1 ) rather stout; total body length (combined length of head, pronotum, elytra, and abdomen) 1.85 mm. Body reddish brown, with mouthparts and tarsi paler, integument of dorsal surface densely covered with suberect fine setae. Head slightly broader than long; length from anterior margin of clypeus toward base 0.30 mm, width across eyes 0.41 mm; eyes roundly prominent, each composed of approximately 75 facets. Length of antenna 0.86 mm; antennomere I (scape) cylindrical, about 1.65 times as long as wide, antennomere II (pedicel) roundedcylindrical, much narrower than scape, 1.2 times as long as wide, and about 0.6 times as long as scape, antennomeres 3–7 almost moniliform, slightly elongate, antennomere 8 distinctly transverse, antennomeres 9–11 obconical, successively wider apically, antennomere 11 about twice as long as antennomere 10, truncate at base, broadest at near middle, and narrowing toward apex, with inner margin broadly emarginate in apical half (observable in Fig. 1A , right antenna). Maxillary palpi as in Figs 2 B–D; length of palpomere 1 0.03 mm, palpomere 2 0.12 mm, palpomere 3 0.06 mm, palpomere 4 0.12 mm. Pronotum slightly longer than wide, length along midline 0.41 mm, maximum width 0.37 mm; sides roundly expanded laterally. Elytra transverse, length along suture 0.58 mm, maximum width 0.66 mm, anterior margin broadly impressed, posterior margin truncate. Legs moderately elongate, densely setose; ventral margin of mesotrochanters projecting in conspicuous process; mesotibiae bearing small, triangular preapical spur. Abdomen broadest at tergite 1 (IV), length along midline 0.66 mm, maximum width 0.57 mm; tergites and sternites densely covered with suberect, posteriorly directed setae; tergite VIII with deep apical notch at middle of posterior margin.

Remarks. The protuberant mesotrochanters, spinose mesotibiae, and apically notched tergite VIII are interpreted as male sexual characters based on our experience in the extant brachyglutine fauna.

Etymology. The specific epithet refers to the occurrence of this species on the supercontinent Laurasia some 99 million years ago. Adjective.

Figures

Fig. 1. Habitus of †Cretobrachygluta laurasiensis gen. et sp. nov. A – dorsal view; B – ventral view. Scale bar: 0.5 mm.

Fig. 2. Morphological details of †Cretobrachygluta laurasiensis gen. et sp. nov. A – left antenna; B–D – main body parts in dorsal (B), ventral (C), and lateral (D) view, with foveal pattern and other important characters annotated. Scale bar: 0.2 mm in A; 0.5 mm in B–D. Abbreviations: a1–2, 9–11 = antennomeres 1–2, 9–11; bef = basal elytral foveae; blf = basolateral fovea; dc = discal carina; gf = gular fovea; gr = gular ridge; laf = lateral antebasal fovea; lmcf = lateral mesocoxal fovea; lmsf = lateral mesoventral fovea; lmtf = lateral metaventral fovea; maf = median antebasal fovea; mmsf = median mesoventral foveae; mp4 = maxillary palpomere 4; ms = marginal stria; mtc = metacoxa; omc = ocular-mandibular carina; p = projection; plc = posterolateral cleft; s = spur; shef = subhumeral elytral fovea; sIII–VIII = sternites III–VIII; ss = sutural stria; tIV–VIII = tergites IV–VIII; tc = pretarsal claw; ts1–3 = tarsomeres 1–3; vf = vertexal fovea.