Tychon antiquum ( Giebel, 1856 )

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 : 123-124

† Tychon antiquum ( Giebel, 1856)

( Figs. 92 , 116 )

Helephoridae ? [sic!]: BRODIE (1845: 117, Pl. vi: Fig. 13 ). Helophorus antiquus Giebel 1856: 51 . Tychon antiquum: HANDLIRSCH (1908: 563 , Pl. XLV: Fig. 76 ; transferred to Tychon ). Helophorus antiquus: HANSEN (1999: 318) .

Type locality. United Kingdom, Wiltshire, Vale of Wardour, Middle Purbeck. Early Cretaceous, Middle Berriasian, 145.5–140.2 mya ( CLAPHAM 2011a).

Type material: HOLOTYPE: NHM I-11967 (piece only).

Taxonomic note. The holotype, which is the only available specimen of the species, is a badly preserved fossil with partly preserved elytra in dorsal view, whereas all remaining body parts are missing. Hence, the fossil does not bear any apomorphy or combination of characters indicating its placement within the Hydrophiloidea . The assignment to the Hydrophiloidea was supposed as unjustified even by HANDLIRSCH (1908) who also considered the species to be of an unclear placement within Coleoptera . We are confirming this opinion here and exclude the species as well as the monotypic genus Tychon Handlirsch, 1908 to which it belongs from the Hydrophiloidea to Coleoptera incertae sedis.

Figures

Figs. 89–93. Representatives of Helophorus, subgenus Mesohelophorus Ponomarenko, 1977 (89–90) and taxa excluded from the helophorid lineage (91–93). 89–90 – Helophorus palaeosibiricus nom. nov., PIN 3063/841, holotype, piece and counterpiece; 91 – Helophoropsis brodiei (Giebel, 1856), holotype. 92 – Tychon antiquum (Giebel, 1856). holotype. 93 – Zetemenos sexlineatus Bode, 1953, holotype. 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.

Figs.9–13. Laetopsia gen. nov. 9 – L. hydraenoides (Prokin, Ren & Fikáček, 2010), holotype. 10–11 – L. mongolica (Ponomarenko, 1987) (10 – PIN 3664/1567, holotype; 11 – PIN 3664/1661). 12–13 – L. shatrovskiyi (Prokin, Ren & Fikáček, 2010) (12 – CNU 2010199; 13 – CNU 2010242, holotype). Scale bars: 2 mm (a: Figs. 9, 12–13; b: Figs. 10–11). Abbreviations: ant – antenna; sct – scutellum.

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).