Revision of Mesozoic fossils of the helophorid lineage of the superfamily Hydrophiloidea (Coleoptera: Polyphaga) Author Fikáček, Martin Department of Entomology, National Museum, Kunratice 1, CZ- 148 00 Praha 4, Czech Republic; e-mail: mfikacek @ gmail. com & Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, CZ- 128 44 Praha 2, Czech Republic; e-mail: jprokop @ natur. cuni. cz Author Prokin, Alexander Papanin Institute for Inland Water Biology, Russian Academy of Science, Borok, Russia; e-mail: prokina @ mail. ru & Voronezh State University, Research-Educational Centre “ Venevitinovo ”, Voronezh, Russia Author Angus, Robert B. Department of Entomology, The Natural History Museum, London, UK; e-mail: r. angus @ rhul. ac. uk Author Pono, Alexander Author Marenko Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, Russia; e-mail: aponom @ paleo. ru Author Yue, Yanli School of Life Science, Ningxia University, Ningxia, China; e-mail: yueyanli 0407 @ yahoo. cn Author Ren, Dong Author Prokop, Jakub Department of Zoology, Faculty of Science, Charles University in Prague, Viničná 7, CZ- 128 44 Praha 2, Czech Republic; e-mail: jprokop @ natur. cuni. cz text Acta Entomologica Musei Nationalis Pragae 2012 2012-06-30 52 1 89 127 journal article 10.5281/zenodo.5330604 0374-1036 5330604 † Laetopsia mongolica ( Ponomarenko, 1987 ) comb. nov. ( Figs. 10–11 , 58–60 ) Hydrophilopsia mongolica Ponomarenko, 1987: 97 . Type locality and age. Mongolia , Shin Khuduk, Middle-Gobi province . Lower Cretaceous , Hautervian to Barremian, ca. 136–125 mya ( DURANTE & BAKULBEKOV 2009 ; Vasilenko , pers. comm. to A. Prokin , 2011) . Material examined ( 17 spec. ). HOLOTYPE : PIN 3664/1567 (piece only). PARATYPES : PIN 3664/1480 (piece only); PIN 3664/1493 (piece only); 3664/1569 (piece only); PIN 3664/1573 (piece only); PIN 3664/1574 (piece only); PIN 3664/1583 (piece only); PIN 3664/1587 (piece only); PIN 3664/1642 (piece only); PIN 3664/1650 (piece only); PIN 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. 3664/1655 (piece only); PIN 3664/1661 (piece only); PIN 3664/1663 (piece only); PIN 3664/1672 (piece only); PIN 3664/1683 (piece only); PIN 3664/1771 (piece only); PIN 3664/1772 (piece only); PIN 3664/1784 (piece only). Redescription. Body elongate oval, 8.0– 9.5 mm long ( holotype 9.5 mm ). Head with protruding eyes, frontoclypeal suture Y-shaped, with grooved median portion; anterior margin of clypeus straight; labrum transverse, tightly attached to anterior margin of clypeus. Gula slightly constricted but gular sutures still widely separate. Pronotum with median longitudinal groove, pronotal flanks narrow, widest anteriorly, narrowing posteriad; prosternum long anterior to procoxae. Elytral striae 1–8 darkened; scutellary stria absent. Mesocoxae contiguous, metaventrite much longer than mesoventrite, metepimeron wide. Abdomen with 5 ventrites. Note. The specimens examined show a wide variation in body proportions which are likely the result of deformations during the fossilization process. Besides these differences, we did not find any indication that more species should be present at the locality. Therefore, in agreement with the original description, we treat all specimens as a single species. Laetopsia mongolica clearly differs from both Laetopsia species from the Yixian formation which is considered as roughly of the same age as Shin Khuduk by some authors ( SWISHER et al. 1999 ) and was/is moreover rather close to it geographically – it has continually arcuate lateral margins of pronotum (in contrast to angulate margins in L. hydraenoides ) and rather narrow prosternum in front of procoxae (in contrast to long precoxal portion of prosternum in L. shatrovskiyi ).