Laetopsia baissensis ( Ponomarenko, 1987 ) 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 : 94-95

† Laetopsia baissensis ( Ponomarenko, 1987) comb. nov.

( Figs. 5–8 , 53–56 , 104–106 )

Hydrophilopsia baissensis Ponomarenko, 1987: 95 .

Type locality and age. Russia, Buryat Republic, Baissa outcrops [ river Vitim below the mouth of the Baissa River]. Early Cretaceous, Berriasian to Hauterivian, ca. 146–135 mya ( ZHERIKHIN et al. 1998; Vasilenko, pers. comm. to A. Prokin, 2011)

Material examined (23 spec.). HOLOTYPE: PIN 3064/6985 (piece and counterpiece). PARATYPES: PIN 3064/6979 (piece and counterpiece), PIN 3064/6984 (elytron), PIN 3064/6988 (piece and counterpiece), PIN 3064/6991 (piece only), PIN 3064/7002 (piece only), PIN 3064/7011 (piece only), PIN 3064/7018 (piece and counterpiece). OTHER MATERIAL (possibly including additional paratypes): PIN 3064/3037 (piece only), PIN 3064/6861 (fragment of an elytron), PIN 3064/6967 (piece only), PIN 3064/6968 (piece only), PIN 3064/6978 (piece only), PIN 3064/6981 (piece only), PIN 3064/6986 (piece and counterpiece), PIN 3064/6987 (piece only), PIN 3064/6989 (piece only), PIN 3064/6990 (piece only), PIN 3064/6997 (piece only), PIN 3064/7003 (fragment of an abdomen), PIN 3064/7009 (piece only), PIN 3064/7010 (piece only), PIN 3064/7017 (piece only).

Redescription. Body elongate oval, 6.7–7.7 mm long (holotype 7.4 mm). Head with narrow postocular bridge, mentum probably transverse, labrum transverse, attached on anterior margin of head, gula wide. Antenna with three-segmented club and well developed cupula, pedicel conical. Pronotum slightly narrowed basally, arcuate laterally, bearing a median longitudinal groove, lateral margins smooth. Prosternum well-developed, ca. as long as procoxal cavities, pronotal flanks narrow, slightly narrowing posteriad, ridge delimiting their inner margin sinuate. Mesanepisterna not meeting medially, mesoventrite strongly narrowing anteriad, sutures slightly arcuate, without transverse ridge posteriorly. Mesocoxal cavities only very narrowly divided from each other. Elytral series 1–8 darkened, scutellary stria absent, all elytral intervals of the same height; epipleuron subdivided into inner and outer portion, inner portion narrow. Metaventrite much longer than mesoventrite, metanepisternum with oblique transverse ridge anteriorly. Abdomen with five sparsely punctate ventrites, posterior margin of ventrite 5 with rectangular teeth.

Note. Laetopsia baissensis lacks the transverse ridge on the mesoventrite ( Fig. 107 ) which is otherwise a synapomorphy shared by all representatives of the helophorid lineage. This might indicate that L. baissensis is not congeneric with the remaining Laetopsia species and may not even belong to the helophorid lineage. However, L. baissensis shares all remaining characters with L. shatrovskiyi (type species of Laetopsia gen. nov.), including the dark stripes on the elytra and a single median groove on pronotum. For this reason, we rather consider the species as an aberrant representative of Laetopsia gen. nov. which indicates that the morphology of the mesoventrite may have varied in Laetopsia gen. nov. in similar extent as it does in some modern hydrophiloid genera (e.g., in Anacaena Thomson, 1859 , Hydrophilidae ).

Figures

Figs.5–8. Laetopsia baissensis (Ponomarenko, 1987). 5 – PIN 3064/7018; 6 – PIN 3064/7010, detail of prosternum; 7 – PIN 3064/6987; 8 – PIN 3064/6984, elytron. Scale bars 2 mm (a: Fig. 5, b: Fig. 6, c: Figs. 7–8). Abbreviations: ant – antenna; sct – scutellum.

Figs. 53–62.Representatives of Laetopsia gen.nov.53–56 – L.baissensis (Ponomarenko, 1986) (53 – PIN 3064/7016; 54–55 – PIN 3064/6987, piece and counterpiece; 56 – detail of PIN 3064/6987). 57, 61 – L. hydraenoides (Prokin, Ren & Fikáček, 2010), CNU 2010021, holotype (57 – detail of head and pronotum; 61 – general view). 58–60 – L. mongolica (Ponomarenko, 1987) (58 – PIN 3664/1661, detail of head and pronotum; 59 – PIN 3664/1772; 60 – PIN 3664/1567, holotype). 62 – L. bontsaganica (Prokin, 2009), holotype. Scale bars: 1 mm.

Figs. 104–112. Mesozoic representatives of the helophorid lineage, scanning electron micrographs. 104–106 – Laetopsia baissensis (Ponomarenko, 1986), PIN 3064/7018 (104 – general view; 105 – detail of head and pronotum; 106 – detail of meso- and metathorax). 107, 111 – Helophorus (Mesosperchus) inceptivus sp. nov. (107 – general view; 111 – detail of pronotum). 108–112 – Helophorus (Mesohelophorus) paleosibiricus nom. nov. (108 – PIN 3064/6981, general view; 109 – PIN 3063/863, holotype, 110 – PIN3064/6981, detail of prothorax, ventral view; 112 – same, dorsal view).