Helophorus (Mesohelophorus) palaeosibiricus, 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 : 109-119

† Helophorus (Mesohelophorus) palaeosibiricus nom. nov.

( Figs. 38–41 , 87–90, 108–110, 112)

Mesohelophorus sibiricus Ponomarenko, 1977b: 113 (secondary homonym of Helophorus (Gephelophorus) sibiricus (Motschulsky, 1860)) .

Type locality and age. Russia, Buryat Republic, Baissa. Early Cretaceous, Berriasian to Hauterivian, ca. 146–135 mya ( ZHERIKHIN et al. 1998; Vasilenko, pers. comm. to A. Prokin, 2011) .

Material examined (8 spec.). HOLOTYPE: PIN 3064/841 (piece and counterpiece). PARATYPES: PIN 3064/931 (piece and counterpiece), PIN 1989/2998 (piece only). ADDITIONAL NON- TYPE SPECIMENS: PIN 3064/6983 (piece and counterpiece), PIN 3064/884 (piece and counterpiece), PIN 3064/6976 (piece and counterpiece), PIN 3064/6980 (piece and counterpiece), PIN 1989/3038 (piece only).

Redescription. Adult: Body widely elongate, 3.2–3.6 mm long (holotype 3.3 mm). Head with very distinct slightly grooved frontoclypeal suture, clypeus and frons bearing sparse but

83–88. Representatives of Helophorus , subgenera Mesosperchus Ponomarenko, 1977 (83–86) and Mesohelophorus Ponomarenko, 1977 (87–88). 83–84 – PIN 3063/735, holotype of Mesohelophorus elongatus Ponomarenko, 1990 (= Helophorus tarsalis (Ponomarenko, 1977)) (piece and counterpiece). 85–86 – Helophorus yixianus sp. nov., CNU 2010004, holotype (85 – detail of head and pronotum; 86 – general view, under alcohol). 87–88 – Helophorus palaeosibiricus nom. nov., PIN 3064/6981, piece and counterpiece. Scale bars: 1 mm.

very distinct granulation. Mentum ca. as wide as long, gula strongly constricted, gular sutures joint in a point; antenna with three-segmented club. Pronotum slightly narrowing anteriad, with slightly arcuate lateral margins; pronotal surface with three longitudinal grooves, intervals bearing strong and rather dense granulation; pronotal flanks narrow, slightly narrowing posteriad, divided from hypomeron by sinuate ridge. Prosternum moderately long, ca. half as long as procoxal cavity. Mesoventrite very narrow at anterior margin, bearing transverse ridge posteromedially. Metaventrite slightly longer than mesoventrite, metepimeron rather narrow. Elytron with 10 punctate series, scutellary stria well developed, consisting of more than five punctures; elytral intervals not elevated or costate; epipleuron wide anteriorly, subdivided in inner and outer portions of equal width. Abdomen with 5 ventrites. Legs rather short and stout.

Taxonomic note. By transferring the species to the genus Helophorus , Mesohelophorus sibiricus Ponomarenko, 1977 becomes the secondary homonym of a modern species Helophorus (Gephelophorus) sibiricus (Motschulsky, 1860) . In order to eliminate the homonymy, we are hereby proposing a new substitute name for the fossil species, H. palaeosibiricus nom. nov.

Figures

Figs. 38–41. Helophorus (Mesohelophorus) palaeosibiricus nom. nov. 38–39 – PIN 3063/841, holotype, piece and counterpiece; 40–41 – PIN 3064/6981, piece and counterpiece. Scale bars: 0.5 mm.