Alegorius yixianus, 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 : 717

ALEGORIUS YIXIANUS 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, Wang & Wang, 1999). An alternative dating was proposed by Zheng, Zheng & Xing (2003): Jurassic–Cretaceous boundary, Late Tithonian–Berriasian, c. 145–140 Mya. See Ren et al. (2010) for discussion on various datings of the formation.

Material examined (seven specimens): Holotype: CNU 2009079 , piece only ( Figs 2A , 7A–C ) . Paratypes: CNU 2009078 , piece only ( Figs 2B , 7D–E ) ; CNU 2009077 , piece only ; CNU 2009080 , piece only . Additional specimens examined: CNU 2010024 , piece only ; CNU 2010025 , piece only (all CNU specimens from the type locality) ; NIGP 156965 , piece only [specimen from the Lower Cretaceous Yixian Formation of Liutiaogou , Yangshuwanzi Village , Ningcheng County, Chifeng City, Inner Mongolia, China; see Wang et al. (2012) details of the locality] .

Description: Body elongate oval; for body measurements see Table 1.

Head c. as long as wide. Clypeus slightly explanate laterally, shallowly concave on anterior margin; lateral portions appear paler than central portion. Eyes moderately large, oval, divided by c. 1.8– 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 transverse, partly exposed anterior to clypeus, straight to slightly convex on anterior margin. Maxillary basistipes subtriangular, maxillary palpi probably rather long ( CNU 2009078, Fig. 2A ). Mentum subrectangular, c. 1.5× wider than long.

Prothorax. Pronotum transverse, slightly narrowing anteriad, anterolateral corners slightly projecting anteriad; lateral margins arcuate; pronotal surface flat, without grooves or distinct sculpture. Prosternum anterior to procoxae moderately long, elevated or carinate medially; prosternal process short. Procoxal cavities contiguous. Posterior prothoracic opening wide, transverse fold well developed.

Mesothorax. Mesoventrite with lateral wing-like projections, wide at anterior margin; anapleural sutures strongly curved, subparallel anteriorly, widely separated anteriorly; mesepimeron quadran- gular. 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.

Metathorax. Metaventrite evenly flat, slightly longer than mesoventrite, anteriorly narrowly projecting between mesocoxae, only weakly projecting posteriad. Metanepimeron narrow, 2.9× as long as wide, with a transverse oblique ridge anteriorly. Metacoxal cavities transverse, contiguous mesally.

Legs moderately long, apices of femora c. reaching body outline. Metacoxae transverse. Metatrochanter subtriangular. Metafemur with anteroproximal portion free, not facing trochanter. Tibiae c. as long as femora; meso- and metatibiae with longitudinal series of small spines and longer apical spurs; mesotarsus with basal tarsomere minute, tarsomere 2 much longer, subequal in length to tarsomeres 3–4 combined, tarsomere 5 longest, bearing simply arcuate claws.

Abdomen with five ventrites, posterior margin of ventrite 5 with deep narrow emargination.

Differential diagnosis: Alegorius yixianus sp. nov. differs from the unnamed below species in much larger body size (c. 10–12 mm, in contrast to 6.4 mm in Alegorius sp. ).

Etymology: The species name refers to the Yixian Formation, where the fossils of this species were excavated.

Figures

Figure 2. Alegorius yixianus gen. nov., sp. nov. from the Yixian Formation, China. Holotype, CNU 2009079 (A); paratype, CNU 2009078 (B). Abbreviations: abem, apical emargination of abdominal ventrite 5; aes3, metanepisternum; bst, maxillary basistipes; fmtta, free metatibial anterobasal angle; lb, labrum; men, mentum; mstr1, mesotarsomere 1; msv, mesoventrite; pros, prosternum; sstr, sutural stria; tf, transverse fold of prothorax.

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.