Cretoxenus australis, Fikáček & Prokin & Yan & Yue & Wang & Ren & Beattie, 2014

Fikáček, Martin, Prokin, Alexander, Yan, Evgeny, Yue, Yanli, Wang, Bo, Ren, Dong & Beattie, Robert, 2014, Modern hydrophilid clades present and widespread in the Late Jurassic and Early Cretaceous (Coleoptera: Hydrophiloidea: Hydrophilidae), Zoological Journal of the Linnean Society 170 (4), pp. 710-734 : 721-722

CRETOXENUS AUSTRALIS SP. NOV.

Coleoptera indet.: Jell & Duncan 1986: fig. 40I–K.

Type locality and age: Australia, Victoria State, Koonwarra Fossil Bed, road cutting on South Gippsland Highway, 1.5 miles west of Tarwin & 2.5 miles east of Koonwarra (93.5 miles south-east of Melbourne). Korumburra Group , Early Cretaceous , Late Aptian , c. 118–112 Mya (Dettmann, 1986; Jell & Duncan, 1986) .

Type material: Holotype: NMVP 103312 , piece and counterpiece, partly damaged ( Figs 3A–B , 6I–J ).

Description: Body elongate oval, body length 7.7 mm, width of head 1.5 mm, width of pronotum 2.7 mm, elytral length 4.7 mm.

Head c. as long as wide. Clypeus slightly explanate laterally, shallowly concave on anterior margin. Eyes moderately large, oval, divided by c. 2.3× the width of one eye; postocular bridge not developed. Gula slightly narrowing anteriad, weakly carinate medially in posterior portion; gular sutures widely separate from each other. Labrum rather large, well sclerotized, transverse, attached to anterior margin of clypeus. Antenna with terminal club. Maxillary palpi slender and long, probably as least as long as width of head.

Prothorax. Pronotum transverse, slightly narrowing anteriad, anterolateral corners slightly progressing anteriad; lateral margins arcuate, finely rimmed; pronotal surface flat, without grooves or distinct sculpture. Prosternum anterior to procoxae moderately short, prosternal process simply projecting between procoxae, median portion of prosternum without distinct carina. Procoxal cavities contiguous. Posterior prothoracic opening wide, transverse fold well developed.

Mesothorax. Mesothorax with narrow anterior collar; mesoventrite triangular, strongly narrowed anteriad, rather narrow on anterior margin; anapleural sutures well developed, slightly arcuate; mesepimeton quadrangular. Mesocoxal cavities only very narrowly separated from each other. Scutellar shield rather small, triangular, sharply pointed posteriorly. Elytron with deeply impressed sutural stria and weakly impressed series of fine punctures; epipleuron well developed, rather wide anteriorly, subdivided by a ridge into a narrower outer and wider inner portion.

Metathorax. Metaventrite c. as long as mesoventrite, posteriorly narrowly projecting between metacoxae, its median portion probably slightly elevated at least posteriorly. Metanepimeron narrow, 4.1× as long as wide. Metacoxal cavities transverse, contiguous mesally.

Legs moderately long, apices of femora c. reaching body outline. Procoxae globular, mesocoxae transversely oval, metacoxae transverse. Metatrochanter sinuate on inner margin. Tibiae c. as long as femora. Mesotibia with two dorsal longitudinal series of small spines, third series of spines present on its posterior face; apical portion of mesotibia with series of moderately long spurs. Mesotarsus with very short basal tarsomere, tarsomere 2 rather long.

Abdomen with five ventrites.

Etymology: The species name refers to Australia, i.e. the country of origin of the fossil.

Figures

Figure 3. Early Cretaceous representatives of the Hydrobiusini. Cretoxenus australis gen. nov., sp. nov., Koonwarra, Australia, NMVP 103312, piece and counterpiece (A, B). Baissalarva hydrobioides gen. nov., sp. nov. from Baissa, Russia: paratype PIN 3063/6977 (C); holotype PIN 3063/6975: piece, detail of the head (D), counterpiece, detail of the head (E), whole specimen, counterpiece (F). Abbreviations: absc, abdominal dorsal sclerite; absc4, absc7, abdominal dorsal sclerite of segment 4 or 7; aes3, metanepisternum; apls, anapleural suture; cersc, cervical sclerite; dpl8, dorsal plate on abdominal segment 8; epl, epistomal lobe; md, mandible; men, mentum; mssc, mesoscutum; mstr1, mesotarsomere 1; msv, mesoventrite; mxp, maxillary palpus; mtsc, metascutum; ns, nasale; occf, occipital foramen; pros, prosternum; sbm, submentum; scsh, scutellar shield; sstr, sutural stria; ttr, tracheal trunk.

Figure 6. Fossil and recent representatives of the Hydrobiusini and Hydrophilini. Baissalarva hydrobioides sp. nov.: holotype PIN 3063/6975, anterior part of the piece (A), detail of the head of the piece (B), detail of the head of the counterpiece (C); paratype PIN 3063/6977 (D). Larva of extant Limnoxenus niger (Hydrobiusini): whole larva in dorsal view (E), detail of head (G). Larva of extant Sternolophus rufipes (Hydrophilini): whole larva in dorsal view (F), detail of head (H). Holotype of Cretoxenus australis sp. nov. NMVP 103312, piece and counterpiece (I, J). Extant hydrobiusine Limnoxenus zealandicus in ventral view, whole beetle (K) and detail of meso- and metaventrite (L). Abbreviations: md, mandible; mtvpr, metaventral process.