Hydroyixia latissima, 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 : 727-728

HYDROYIXIA LATISSIMA SP. NOV.

Type locality and age: China, Liaoning Province, Shangyuan County, Chaomidian Village, Huangbanjigou, Yixian Formation, Early Cretaceous, Lower Cretaceous, Aptian, 124.6 Mya ( Swisher et al., 1999). An alternative dating was proposed by Zheng et al. (2003): Jurassic–Cretaceous boundary, Late Tithonian to Berriasian, c. 145–140 Mya. See Ren et al. (2010) for discussion on various datings of the formation.

Material examined (three specimens): Holotype: CNU COL LB 2009074, piece only ( Figs 5F–G , 7M–O ). Paratypes : CNU COL LB 2009107, piece only ( Fig. 5I ); CNU COL LB 2010014, piece only, with detached posterior leg ( Fig. 5H ).

Description: Body widely oval. For body measurements see Table 1.

Head. Clypeus large; frontoclypeal sutures very distinct, reaching lateral margin of head closely before eyes; anterior margin excised, excision angular laterally. Eyes rather large, separated by 2.3× the width of one eye. Labrum transverse, partly exposed anterior to clypeus, slightly narrowing posteriad, weakly convex on anterior margin. Gula narrowing anteriad, with longitudinal ridge mesally, gular sutures widely separated. Mentum rather small, subrectangular, c. 2.4× wider than long.

Prothorax. Pronotum transverse, slightly narrowing anteriad; lateral margin arcuate. Prosternum probably rather long, with median elevation or carina. Procoxae contiguous.

Mesothorax. Mesoventrite subtriangular, extremely narrow at anterior margin. Anapleural sutures well developed, slightly curved, converging anteriad, joint at anterior margin of mesoventrite. Mesepimeron large, subtriangular. Mesocoxae only narrowly separated. Scutellar shield small, triangular, pointed posteriorly. Elytra combined widest anteriorly; each elytron with sharply impressed sutural stria; elytra with coarsely punctate elytral series; epipleuron well developed anteriorly, moderately wide.

Metathorax. Metaventrite much longer than mesoventrite, probably not elevated mesally, narrowly projecting between mesocoxae anteriorly; only slightly projecting posteriad. Anepisternum 4.4× as long as wide.

Abdomen with five ventrites; ventrite 5 with shallow wide apical emargination.

Differential diagnosis: For differential diagnosis from H. elongata see above under that species.

Etymology: The species name refers to the wide body of this species.

Figures

Figure 5. Well-preserved specimens of Hydroyixia gen. nov., Yixian Formation, China. Hydroyixia elongata sp. nov.: holotype CNU 2010005, piece and counterpiece (A, B); paratype CNU 2009075, whole specimen (C), detail of head and pronotum (D); detail of elytral apices (E). Hydroyixia latissima sp. nov.: holotype, CNU 2009074, whole specimen (F), detail of abdominal apex (G); posterior leg of paratype CNU 2010014 (H); paratype CNU 2009107 (I). Abbreviations: abem, apical emargination of abdominal ventrite 5; aes3, metanepisternum; apls, anapleural sutures; cl, clypeus; fcs, frontoclypeal suture; gs, gular suture; lb, labrum; men, mentum; msv, mesoventrite; mtv, metaventrite; mttr1, metatarsomere 1; pros, prosternum; sstr, sutural stria; trich, trichobothrium.

Figure 7. Hydrophilid fossils from Early Cretaceous Yixian Formation, China. Alegorius yixianus sp. nov.: holotype CNU 2009079, whole specimen (A), detail of meso- and metaventrite (B), detail of abdominal apex (C); paratype CNU 2009078, whole specimen (D), detail of mesoventrite (E). Hydroyixia elongata sp. nov.: paratype CNU 2009075, detail of head and pronotum (F), whole specimen (G); holotype CNU 2010005: whole beetle, piece and counterpiece (H, I), detail of head (J), detail of meso- and metaventrite (K), detail of abdominal apex (L). Hydroyixia latissima sp. nov.: holotype CNU 2009074, detail of abdominal apex (M), whole specimen in dry condition (N) and under alcohol (O). Abbreviations: apls, anapleural suture; abem, apical emargination of abdominal ventrite 5.