Mathesius liaoningensis Kolibáč & Huang, 2011, sp. nov.
Creators: name: Kolibáč, Jiří
name: Huang, Di-Ying
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Nitidulidae
Mathesius
Mathesius liaoningensis

description: Mathesius liaoningensis sp. nov.
(Figs 1–16)
Type specimen. Holotype (male) NIGP 152355. Unique specimen housed in Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China.
Type locality and stratigraphic horizon. Huangbanjigou Village, Beipiao City, Liaoning Province, NE China; Lower Cretaceous Yixian Formation (ca. 125 Ma).
Description. Measurements: body length without mandibles (from elytral apex to clypeus) 12.1 mm; head length (visible part without mandibles) 2.3 mm, width 3.8 mm; pronotum length 2.1 mm, width 3.8 mm; elytra length 7.7 mm; width of each elytron 2.1 mm. See Fig. 1 for review of measurements.
Coloration and sculpture not preserved, punctation of head and pronotum probably very fine or their dorsal surface smooth; elytral punctation and carinae not observed. See Remark 1 for a note on preservation.
Head prognathous, as wide as rest of body, perfectly fitted in prothorax, widest behind eyes (nearly twice as wide as long); cranium dorsally without wrinkles or grooves (medial groove in Fig. 3 artificial); frontoclypeal suture conspicuous, incurvate backwards; anterior margin of cranium with distinctly projecting horn at each side; antennal sockets situated between eyes and horns, partly visible from above, i.e., only weakly covered by edge of cranium; eyes relatively small, not elevated, their facetation inconspicuous; space between eyes more than five times as wide as eye diameter; clypeus large, oblong, probably free; labrum distinctly narrower than clypeus, its anterior margin straight but small anteriorly situated projection present in center; mandible relatively large, sharp, probably unidentate or very weakly bidentate (see Fig. 14: two small sharp teeth observed in left mandible; position of teeth is unclear—see Remark 2, they may be partly situated in horizontal axis or side by side), probably without mola, without medial tooth, with at least six small teeth situated along inner (cutting) edge; labial palps elongate, approximately as long as mandibles or slightly longer, terminal palpomere slender and elongate but truncate at apex; maxillary palps somewhat shorter and distinctly thinner than mandibles, their terminal palpomere elongate, coniform, base of each palpomere slender than apex of previous one; antennae 11-segmented: scapus not distinctly enlarged (as for example in Trogossitidae) but weakly wider than other antennomeres, its base partly covered by edge of cranium, pedicellus smallest than other antennomeres, third antennomere longer than each of others, antennomeres 9 and 10 dilated at apices, antennal club very weak (nearly inconspicuous), terminal antennomere evenly rounded at apex.
Prothorax distinctly transverse; nearly twice as wide as long in the widest portion; distinctly narrowed towards base; prosternal process wide, conspicuously dilated at apex (but apical margin itself not visible); procoxal cavities nearly rounded, probably not perfectly externally closed (Fig. 11).
Mesothorax: mesonotum distinctly visible, transverse, with differentiated scutum and scutellum; mesepisterna and mesepimera inconspicuous in fossil (blocked by legs); mesoventrite with acuminate mesoventral process, its outline in Fig. 15; mesocoxal cavities rounded, weakly transverse, narrowly separated; elytra oval, covering whole abdomen, the widest approximately in 2/3 of length, probably without carinae; elytral epipleure relatively thin, its width seems to be even along whole outer margin.
Metathorax: Metaventrite trapezoidal, its base wider than anterior part; metepisternum distinct, elongate; metepimeron probably also elongate, running along metepisternum as in modern cleroids; paracoxal sutures sinuate; discrimen (discriminal line) not visible—if present, coincides with elytral suture in the specimen; metathoracic wings present (Figs 9, 15): conspicuous veins, probably radius (see Remark 3), run along proximal side of metepisternum/metaventrite suture; left radius probably with part of radial cell (probably trapezoidal in shape if Rc was perfect in the species).
Legs: procoxae probably spherical and somewhat projecting, divided by wide prosternal process; mesocoxae oval in shape, not distinctly transverse, narrowly separated; metacoxae elongate, transverse, narrowly separated; all trochanters triangular, compact, relatively small; femora distinctly clavate (pro- and metafemora well visible), with projecting and elongate bases (its shape is best-visible in metafemora); tibiae not dilated or weakly dilated towards apex; large spines, hooked spurs or robust thorns along sides and at apex of tibiae not observed but metatibiae probably with row of fine spines along inner margin (Fig. 16) and protibia probably with fine straight apical spur; metatarsi (Fig. 16) 5-segmented with first tarsomere elongate, widened at apex (probably lobed), distinctly longer than the second, approximately as long as 2–4 together; the second and third tarsomeres same in size and shape, with conspicuous short lobes (see Remark 4); the fourth tarsomere thinner than previous two, as long as or little shorter than the third one and inserted into it; the last tarsomere elongate, probably slightly shorter than the first one; claws probably without denticles; tarsal pattern probably 5-5-5; tarsal length ratio approximately 4:5:6 (or 1:1.3:1.6 according to computer measuring in Fig. 2).
Abdomen probably with six visible ventrites (see Remark 5). Aedeagus (approximate outline in Fig. 12): phallobase with conspicuous robust medial apodeme and probably paired struts (see Remark 6); apical part of tegmen divided into two parameres; only slender basal part of phallus is probably observed.
Coloration and sculpture not preserved, punctation of head and pronotum probably very fine.
Remarks. Several character states mentioned above in the section „Description“ are discussed here:
1. Due to the way of preservation, the fossil is semitransparent and its structures are gradually perceptible from dorsal to ventral side. However, some of normally hidden structures are visible in as same layer as visible ones (for example margins of abdominal tergites/ventrites).
2. The shape of the mandibular apex is not perfectly visible. Probably, the mandibles are unidentate or very weakly bidentate. By all means, the mandibles are sharp, suitable for predacious way of life.
3. The depicted wing veins are distinct but incomplete, therefore, their exact identification is somewhat uncertain. Probably, they can be determined, according their shape and position in the thorax, as the radius with proximal part of the radial cell. However, the medial field veins (or their cross) can be also similar in the shape, thus, the exact identification of the both veins observed stays uncertain.
4. The lobes in the metatarsomeres 2 and 3 are distinct; the lobes in the basitarsus and tarsomere 4 are not so conspicuous in the fossil but we also suppose their presence.
5. A number of visible ventrites: there are five margins distinctly visible among abdominal segments but the margin between I–II (Fig. 2) could be a tergal (dorsal) one in fact. Therefore, although six visible ventrites are more probable in the fossil, the virtual presence of five ventrites only is not excluded.
6. The aedeagus: parameral part, shape of tegmen and medial phallobasic apodeme are conspicuous in the fossil. Three other rod-like structures are visible but their identification is uncertain. We suppose there are two phallobasic struts and slender phallus around phallobasic apodeme but the presence of two phallic struts is not excluded. In such case, the third rod-like structure is one phallobasic strut of a pair; the second phallobasic strut is artificially missing.
Etymology. The species is named after the Chinese province Liaoning where the fossil had been found.
description: Published as part of Kolibáč, Jiří & Huang, Di-Ying, 2011, Mathesius liaoningensis gen. et sp. nov. of Jehol Biota, a presumptive relative of the clerid or thaneroclerid branches of Cleroidea (Coleoptera), pp. 1-17 in Zootaxa 2872 on pages 5-6, DOI: 10.5281/zenodo.204016