Jurodes ignoramus Ponomarenko, 1985

Yan, Evgeny V., Strelnikova, Olesya D. & Ponomarenko, Alexander G., 2021, Jurodidae (Coleoptera: Archostemata) from Transbaikalia: new findings and redescription of type material, Palaeoentomology 4 (6), pp. 604-613 : 605-607

Jurodes ignoramus Ponomarenko, 1985

( Figs 1–3 )

Material. Holotype PIN, 3000/908, part and counterpart of almost fully-preserved beetle; most tibiae and tarsi as well as the abdominal apex are missing . Paratype PIN, 3000/911 from the same locality .

Diagnosis. Pronotum shorter than head; antennomere 10 0.7 times as wide as apical one; antennomere 9 beadshaped, its length and width subequal.

Type locality and horizon. Novospasskoe locality, Middle Jurassic, Ichetui Formation, Russian Transbaikalia.

Description. Head (including mandibles) as long as pronotum and almost as wide; maximum width behind eyes (at the level of the postocular extensions, Fig. 3H —po.e). Medial portion of frons and occiput bear X-shaped elevation, formed by posteromesal protuberance (P3) and posterolateral protuberance (P4). Postocular extensions prominent. Neck region well defined. Mandibles very slightly curved inwards at midlength, apices sharp, preapical tooth present, located very close to apex; median mandibular ridges present, molar areas absent. Labrum trapezoidal, anterior angles widely rounded, anterior margin slightly emarginated, posterior margin with triangular median depression. Clypeus lenticular, anterior margin with elevated anterior half. Frons with anterior margin concave; genae carinate. Supraocular protuberances present (P2), stretches along anterior half of inner ocular margin. Antennal sockets located at anterior arms of posteromesal protuberance (P3). Each antennomere with narrow base, separated from main part by fine sulcus. Compound eyes lateral, moderately protruding laterally.

Pronotum as long as wide, its anterior margin not wider than posterior one; sides distinctly curved and carinate; dorsal surface with pair of lenticular median protuberance with longitudinal depression in-between. Pronotal anterior angles acute, protruding anterolaterally. Propleuron distinctly narrowed anterior, not reaching anterior margin of pronotum.

Mesoscutellar shield subtriangular with slightly concave anterior margin and widely-rounded posterior margin. Metanotal alacrista X-shaped, heavily sclerotized.

Elytra carinate; epipleuron narrow, as wide as average distance between at least 13 elytral punctate striae on dorsal surface.

Mesoventrite rhomboid, its anterior margin with semicircular depression. Metaventrite widening posteriorly, its posterior angles protruding laterally beneath metanepisternum posterior margins; anapleural clefts distinct. Metatrochantins very thin, indistinct.

At least pro- and mesofemora with longitudinal keels.

Measurements (in mm). Body length, 6.8, width, 2.6, elytral length, 4.3, elytral width, 1.2.

Remarks. Postocular extensions on holotype bear symmetrical circular structures, which could be remnants of laterally protruding compound eyes.

Mandibles are usually very strongly sclerotized, outlines thus visible below labrum (appearing semitransparent) and filled with grey ( Fig. 3H ).

Epipleuron on Fig. 3A–D drawn as a solid line; even though it is normally invisible in dorsal view, this option was chosen to highlight the distinction between the epipleuron and elytral stria.

In addition to the type series, there are new findings of full-body impressions of J. ignoramus from Khasurty locality (Lower Cretaceous, Buryatia Republic ): PIN, 5026/956 and 957 .

All jurodids display a visible suture between the mesoventrite and mesanepisternum, which results in a rhomboid shape of the former in J. ignoramus . This character differentiates them from Sikhotealinia , which have only the mesepimeron separated by a suture (see Beutel et al., 2008: fig. 13).

Figures

FIGURE 1. Jurodes ignoramus Ponomarenko, 1985. A, Holotype PIN, 3000/908 wetted with 96% ethanol. B, Holotype, counterpart wetted with 96% ethanol. C and D, Paratype PIN, 3000/911 part and counterpart.Scale bars = 1 mm.

FIGURE 2. Jurodes ignoramus Ponomarenko, 1985. А and В, Specimens PIN, 5026/957 and 5026/956 respectively, wetted with 96% ethanol. Scale bars = 1 mm.

FIGURE 3. Jurodes ignoramus Ponomarenko, 1985 interpretative line drawings. A and B, Holotype. C and D, Paratype. E–G, Original line drawings of the holotype from Ponomarenko, 1985 with minor changes. H, Details of holotype’s head. I, Details of holotype’s pronotum. K and J, Specimens from Khasurty locality. Abbreviations: alc, alacrista; an.cl, anapleural cleft; ant.g, antennal groove; ant.s, antennal socket; c.e, compound eye; clp, clypeus; cx3, metacoxae; em3, metepimeron; epl, epipleuron; eps2, mesanepisternum; es3, metanepisternum; fm1,2,3, pro-, meso-, metafemur; gen, genae; lbr, labrum; lts, laterosternite; md.p, pronotal median protuberance; P2, supraocular protuberance; P3, posteromesal protuberance; P4, posterolateral protuberance; po.e, postocular extension; ppl, propleuron; SIII, third abdominal sternite; sc2, mesoscutum; scl2, mesoscutellum; s.prc, paracoxal suture; TIX-X, abdominal tergites; tb1, protibia; tr1,2,3, pro- meso-, metatrochantin; trc1, protrochanter; v2, mesoventrite.All scale bars are equal to 1 mm.