Helophorus (Mesosperchus) gracilis ( Prokin, Ren & Fikáček, 2010 ) Fikáček & Prokin & Angus & Pono & Marenko & Yue & Ren & Prokop, 2012

Fikáček, Martin, Prokin, Alexander, Angus, Robert B., Pono, Alexander, Marenko, Yue, Yanli, Ren, Dong & Prokop, Jakub, 2012, Revision of Mesozoic fossils of the helophorid lineage of the superfamily Hydrophiloidea (Coleoptera: Polyphaga), Acta Entomologica Musei Nationalis Pragae 52 (1), pp. 89-127 : 107-108

† Helophorus (Mesosperchus) gracilis ( Prokin, Ren & Fikáček, 2010) comb. nov.

( Fig. 80 )

Hydrophilopsia gracilis Prokin, Ren & Fikáček, 2010: 178 .

Type locality and age. China, Liaoning Province, Shangyuan County, Chaomidian Village, Huangbanjigou [the name of the villige was misspelled in the original descirption]. Yixian Formation, Jurassic-Cretaceous boundary, Late Tithonian-Berriasian, ca. 145–140 mya ( REN et al. 2010). An alternative dating was proposed by SWISHER et al. (1999): Lower Cretaceous, Aptian, 124.6 mya (see REN et al. (2010) for discussion on various datings of Yixian formation).

Material examined (4 spec.). HOLOTYPE: CNU 2010018 (piece only) . PARATYPES: CNU 2010067 (piece only) ; CNU 2010068 (piece only) ; CNU 2010030 (piece only) .

Redescription. Body elongate oval, 4.2–4.9 mm long (holotype 4.9 mm). Head with distinct Y-shaped frontoclypeal suture. Anterior margin of clypeus straight, attached to well sclerotised transverse labrum. Eyes moderately large, protruding laterad, postocular bridge present. Maxillary palpus rather long, ultimate palpomere asymmetrical. Gula wide, gular sutures widely separate. Pronotum subrectangular, with weakly arcuate lateral margins and without projecting anterolateral corners. Prosternum rather long anterior to procoxae, procoxal cavities contiguous, pronotal flanks narrow, slightly narrowing posteriad. Mesoventrite with transverse ridge posteromedially. Elytron pale, with several elytral series, without dark longitudinal stripes; epipleuron well developed, narrow. Metaventrite ca. twice as long as mesoventrite. Legs rather long, protibia slightly widening apically. Abdomen with 5 ventrites.

Note. The species is known from several rather poorly preserved specimens and was originally assigned to the genus Hydrophilopsia due to its overall similarity to Hydrophilopsia shatrovskiyi and H. hydraenoides ( PROKIN et al. 2010) . In this study we transfer both latter species to the genus Laetopsia defined by characters not preserved in H. gracilis (i.e. the absence of pronotal granulation and presence of the single median pronotal furrow) and by dark longitudinal stripes on elytra which seem to be absent from H. gracilis (even though this may also be due to bad preservation of the specimens). Hence, we found that the placement of H. gracilis in Laetopsia was not justified by any preserved character. On the other hand, the species agrees in all preserved characters with Helophorus (Mesosperchus) as it is redefined here. Hence, we are tentatively transferring Hydrophilopsia gracilis to Mesosperchus , although the crucial character, i.e. the sculpture of pronotum, is not preserved and this placement will require confirmation once additional specimens of this species are available.

The species co-occured with Helophorus (Mesosperchus) yixianus sp. nov. described below, the reasons for considering them as separate taxa are given under the latter species.

Figures

Figs. 73–82. Representatives of Helophorus, subgenus Mesosperchus Ponomarenko, 1977. 73–79 – Helophorus tarsalis (Ponomarenko, 1977) (73 – PIN 3063/116, paratype; 74 – PIN 3063/2192, piece, general view; 75 – PIN 3015/1769; 76 – PIN 3063/2192, counterpiece, detail of male genitalia; 77– PIN 3063/2194. piece under alcohol; 78 – same specimen, counterpiece in dry condition; 79 – PIN 3015/367, holotype). 80 – Helophorus gracilis (Prokin, Ren & Fikáček, 2010), CNU 2010018, holotype. 81–82 – Helophorus inceptivus, PIN 4270/1008 (81 –detail of head and pronotum; 82 – general view). Scale bars: 1 mm (Figs. 73–80, 82); 0.5 mm (Fig. 81).