Juraniscus majeri, Kolibáč & Huang, 2019

Kolibáč, Jiří & Huang, Diying, 2019, New cleroid beetles from the Middle-Late Jurassic of China, Acta Palaeontologica Polonica 64 (1), pp. 143-155 : 148-151

Juraniscus majeri sp. nov.

Figs. 2B , 4B .

ZooBank LSID: urn:lsid:zoobank.org:act:6E188F79-0922-46BE-88CB-748A6ECBA438

Etymology: Named in memory of Karel Majer (1950–2000), an eminent researcher of the melyrid lineage of Cleroidea , for his contribution to the systematics and morphology of the group.

Type material: Holotype NIGP168479 ; male, counterpart absent; perfect dorsal side of specimen preserved, elytra semitransparent (abdomen and metathorax partly visible).

Type locality: Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China.

Type horizon: Haifanggou Formation, Callovian, Middle Jurassic.

Diagnosis.—Antennomeres symmetrical including three terminal ones, progressively dilated from the fifth onwards; pronotum approximately 1.4 times as wide as long; anterior corners of pronotum weakly projecting; meso- and metatarsi with tarsomere 1 conspicuous, slightly shorter than tarsomere 2; tarsal lobes present in tarsomeres 1–4; tarsal claws without denticles.

Description.— Body length (from elytral apex to clypeus): 4.25 mm. For other measurements of visible body parts see Table 3 .

Coloration and sculpture: body elongate, weakly convex; body surface unicolorous, without distinct colour stripes or patches, merely remnants of dark pigmentation. Head with very fine sculpture composed of round punctures; interspaces between punctures as large as puncture diameter. Pronotum with similar fine sculpture but interspaces larger than puncture diameter; pronotal punctures without seta at centre. Elytron without carinae, with sparse sculpture composed of small, round punctures; interspaces the same size as, or larger than, puncture diameter; punctation appears irregular. Body completely without pubescence, short, sparse setae observed only on tibiae and labrum.

Head: frons flat; clypeus not extended anteriorly, distinctly separated by arcuate frontoclypeal suture; antennal socket visible from above; eye relatively large (space between eyes approximately three times eye diameter), distinctly elevated, not emarginate, elliptic, finely facetted; head inconspicuously narrowed behind eyes.

Mouthparts: mandibles medium-sized (not unidentate, slender and sharp), bidentate, acuminate; labrum oblong, weakly emarginate along anterior margin; maxillary palps 3-segmented, terminal palpomere slender, conical.

Antenna: 11-segmented; scape longer and wider than pedicel but not larger than two following antennomeres together; antennomeres symmetrical, progressively dilated from the fifth onwards; whole antenna reaches approximately as far as posterior margin of prothorax. Both antennae recognised in the fossil specimen.

Prothorax: pronotum weakly transverse, approximately 1.4 times as wide as long; anterior margin straight, not emarginate, anterior corners weakly projecting; lateral edge present, evenly rounded; carina along lateral margin of pronotum absent; posterior margin of pronotum arcuate, posterior corners conspicuous but not projecting.

Mesothorax: mesonotum transverse; mesocoxal cavities narrowly separated; membranous wing present.

Metathorax: metaventrite flat and wide, transverse; metacoxal cavities narrowly separated. Elytron with rounded humeral corner, without carinae.

Legs: mesocoxae distinctly oval, metacoxae extended to lateral margin of metathorax; femora very weakly clavate. Meso- and metatibia and meso- and metatarsus clearly visible: tibia without row of distinct spines along outer margin but with conspicuous edge along outer side; metatibia with two apical spines (not visible in mesotibia); tarsomere 1 conspicuous, slightly shorter than tarsomere 2; tarsomere 4 approximately as long as 3; tarsomere 5 as long as 1–4 combined; tarsal lobes distinctly present in tarsomeres 1–4; claws without denticles; empodium probably small (not observed in well-preserved tarsi); tarsal formula unknown, meso- and metatarsi 5-segmented.

Abdomen: six ventrites distinctly visible; cucujoid tegmen with separated parameres present.

Remarks. —Habitus similar to that of Mauroniscidae ( Fig. 4C ), Rhadalidae , Dasytidae , and Malachiidae , with tendency to soft-bodiedness. Sparse sculpture of elytra irregular, composed of fine punctures as in members of above mentioned families. Structure of antenna ( Fig. 2B 4 ) closely comparable with non-serrate but progressively dilated antennomeres in Mauroniscidae (e.g., Amecomycter Majer, 1995 , Mauroniscus Bourgeois, 1911 , Scuromanius Majer, 1995 ), Dasytidae : Danaceinae (e.g., Danacaea Laporte de Castelnau 1836 , Hylodanacaea Pic, 1926 ), and Dasytidae : Chaetomalachiinae (e.g., Dasytiscus Kiesenwetter, 1859 , and Eutrix Majer, 1996). Antennomeres from fourth or fifth distinctly asymmetrical in dasytids and weakly asymmetrical in mauroniscids (cf. Majer 1994a, 1995, 1996, 1999). Tarsomeres 1–4 with small, non-membranous lobes and long, distinct setae directed forwards as in Prionoceridae and some Dasytidae and Malachiidae . Claws simple, without denticles as in mauroniscids; membranous appendages of claws absent or not preserved. Abdomen with six ventrites as in all members of the melyrid lineage apart from Phycosecidae (ventrites I and II connate in Rhadalidae , see Peacock [1987], but their suture is clearly visible). Tegmen with separated parameres as in mauroniscids ( Majer 1995) and exceptionally also in dasytids ( Constantin and Menier 1987; Majer 1999).

Stratigraphic and geographic range. —NE China: Inner Mongolia, Daohugou; Middle Jurassic, Callovian.

Figures

Fig. 2. Melyrid beetle Sinomelyris praedecessor gen. et sp. nov. (A) and cleroid beetle Juraniscus majeri gen. et sp. nov. (B) from the Middle Jurassic Haifanggou Formation of Daohugou Village, Inner Mongolia, China.A. Paratype, NIGP168478; head (A1), dorsal habitus (A2). B. Holotype, NIGP168479; mouth parts dorsally (B1), metatarsus dorsally (B2), dorsal habitus (B3), antenna dorsally (B4). Abbreviations: f1, front femur; l, labrum; m, mandible; p, terminal palpomere of maxillary palp.

Fig. 4. Melyrid beetle Sinomelyris praedecessor gen. et sp. nov. (A), cleroid beetle Juraniscus majeri gen. et sp. nov. (B) from the Middle Jurassic, Haifanggou Formation of Daohugou Village, Inner Mongolia, China, and extant mauroniscid beetle Mauroniscus titschacki Pic, 1954 (C) from Cuzco, Peru. A. NIGP168477; reconstruction of body shape (A1), mesotarsus laterally (A2). B. NIGP168479; reconstruction of body shape (B1), assumed apex of aedeagus dorsally (B2). C. MMBC-SC, dorsal habitus.