Mesosperchus, Ponomarenko, 1977

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 : 120

† ‘ Mesosperchus ’ angulatus Ponomarenko, 1985

( Figs. 100 , 114 )

Mesosperchus angulatus Ponomarenko, 1985b: 63 .

Mesosperchus angulatus: PERKOVSKY (1998: 114 , synonymized with Mesecanus communis (Ponomarenko, 1977)) .

Type locality and age. Russia, Buryat Republic, Novospasskoye village (current GPS coordinates 51.3°N 108.1°E). Ichetuy Formation, Late Jurassic, Oxfordian, 161.2–155.7 mya ( CLAPHAM 2011d).

Material examined. HOLOTYPE: PIN 3000/921 (piece only).

Taxonomic note. The holotype, which is the only preserved specimen, is a rather well-preserved fossil in ventral view, which however does not bear any apomorphy or combination of characters indicating its placement in the Hydrophiloidea . The apical emargination of the abdominal ventrite 5 resembles that present in some groups of the Hydrophilidae but is not enough to justify the placement of the species to this family. At the same time, the presence of the abdominal emargination excludes the placement in the helophorid lineage of the Hydrophiloidea irrespectively to the real placement of the fossil, as abdominal ventrite 5 is entire on posterior margin in all modern and fossil groups of the lineage. Based on the comparison with other fossils from the locality of Novospasskoye, PERKOVSKY (1998) synonymized Mesosperchus angulatus with Mesecanus communis (Ponomarenko, 1977) (considered as belonging to the Agyrtidae by PONOMARENKO (1977b) and NEWTON (1997), and to Leiodidae by PERKOVSKY (1998)). We are not able to comment on the correctness of the species synonymy or family assignment of Mesosperchus angulatus , but we can confirm here that the species does not belong to the Hydrophiloidea . The species may possibly belong to the Elateriformia according to Ch.-Y. Cai (pers. comm. to M. Fikáček, 2012).

Figures

Figs. 94–103. Taxa excluded from the hydrophilid lineage. 94–99 – ‘Mesohelophorus’ mongolicus Ponomarenko, 1986 (94–95 – PIN 3152/4355, holotype, piece and counterpiece; 96, 99 – PIN 3152/4312, piece and counterpiece; 97 – same specimen, detail of head in dorsal view; 99 – head and prosternum of the holotype). 100 – ‘Mesosperchus’ angulatus Ponomarenko, 1985, holotype; 101 – ‘Mesosperchus’ schultzi Ponomarenko, 1985, holotype, piece; 102–103 – ‘Mesosperchus’ notatus Ponomarenko, 1977, holotype (102 – general view; 103 – detail of elytral structure). Scale bars: 0.5 mm.

Figs.113–119.Taxa excluded from the helophorid lineage. 113 – Helo- phoropsis brodiei (Giebel, 1856), holotype; 114 – ‘Mesosperchus’ angulatus Ponomarenko, 1985, holotype; 115 – ‘Mesosperchus’ notatus Ponomarenko, 1977, holotype; 116 – Tychon antiquum (Giebel, 1856), holotype; 117–118 – ‘Mesosperchus’ schultzi Ponomarenko, 1985, holotype, piece and counterpiece; 119 – Zetemenos sexlineatus Bode, 1953, holotype. Scale bars: 1 mm.