Cretaceous Research 86 (2018) 53e59 Contents lists available at ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes Short communication New Scarabaeoidea (Coleoptera) from the Lower Cretaceous Yixian Formation, western Liaoning Province, China: Elucidating the systematics of Mesozoic Hybosoridae ** Yuanyuan Lu a, b, 1, Ruie Nie a, 1, Chungkun Shih c, d, Dong Ren c, , Xingke Yang a, * Ming Bai a, a Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, 92 Box, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China b University of Chinese Academy of Sciences, Yuquan Road, Shijingshan District, Beijing, 100049, China c College of Life Sciences, Capital Normal University, Beijing, 100048, China d Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, USA article info abstract Article history: Two new genera are created to accommodate two new Hybosoridae (Coleoptera: Scarabaeoidea) species: Received 18 September 2017 Sinohybosorus cheni gen. et sp. n. and Sinochaetodus tridentatus gen. et sp. n.. The new species are Received in revised form described and illustrated based on two nearly complete fossil specimens from the Lower Cretaceous 2 January 2018 (Barremiane lower Aptian) Yixian Formation of western Liaoning Province, China. A key of described Accepted in revised form 6 February 2018 species of Hybosoridae from the Mesozoic and a catalog of extinct Hybosoridae are provided. Based on Available online 7 February 2018 the morphological characters, Fortishybosorus ericeusicus Yan, Bai et Ren, 2013 is transferred back to Fortishybosorus instead of Lithohypna in Glaphyridae. The discovery and description of these two new Keywords: fi Fossil taxa provide further evidence for the Jurassic and Cretaceous diversi cation of lineages of Hybosoridae. Yixian Formation Although the extant Hybosoridae constitute a relative small group in Scarabaeoidea, Hybosoridae are a Sinohybosorus relatively old group of scarab beetles with relative high diversity in the Mesozoic. Sinochaetodus © 2018 Elsevier Ltd. All rights reserved. China New genus 1. Introduction information: Appendix B, including 24 fossil species belonging to 18 genera (three extant genera and 15 fossil genera) (Krell, 2000, The Hybosoridae, a cosmopolitan family of Scarabaeoidea, are 2006, 2007; Ocampo & Ballerio, 2006; Ocampo, 2006a, 2006b; very diverse in the tropics. However, some researchers consider the Nikolajev, 2007a, 2007b, 2008, 2010a, 2010b; Nikolajev et al., group as a subfamily Hybosorinae of the family Scarabaeidae 2010, 2012; Kirejtshuk et al., 2011; Yan et al., 2012; Bai et al., 2016). (Allsopp, 1984; Martínez, 1994). We follow Gardner (1935), Paulian The Hybosoridae are a diversity group of relatively small (1939), Lawrence & Newton (1995), Jameson (2002), and Bouchard scarabs. The antenna has nine to ten antennomeres, with a three- et al. (2011) and consider the group as a family. The Hybosoridae segmented club. Some species, particularly in the Australian comprise six subfamilies (five extant subfamilies and one fossil genus Liparochrous Erichson, 1848 and those of the subfamily subfamily) with more than 550 described extant species. In recent Ceratocanthinae, are capable of rolling up their body to form a years, a number of fossil species belonging to Hybosoridae have compact ball. Larvae are known for only several species, and they been described. A catalog of extinct Hybosoridae are provided in were collected in decomposed plant material or under bark. Larvae supplementary information: Appendix A. Additionally, we sum- and adults of some species are known to stridulate (Ocampo, marize a list of the known fossil hybosorids in supplementary 2006a). Recently, we collected two well-preserved fossil scarab beetles from the Yixian Formation of the Lower Cretaceous in Chaomidian * Corresponding author. Village, City of Beipiao, Liaoning Province (detailed locality see Tang ** Corresponding author. et al., 2015, Fig. 1. Map). The complete preservation of the speci- E-mail addresses: [email protected] (D. Ren), [email protected] (M. Bai). mens enabled us to determine the characters of the body of these 1 Contributed equally. https://doi.org/10.1016/j.cretres.2018.02.005 0195-6671/© 2018 Elsevier Ltd. All rights reserved. 54 Y. Lu et al. / Cretaceous Research 86 (2018) 53e59 ancient scarab beetles. Based on these characters, we describe and in Yixian Age (Ding et al., 2001). Recent studies have confirmed that illustrate two new species belonging to two new Hybosoridae the Yixian Formation belongs to the Lower Cretaceous. The precise genera, Sinohybosorus cheni gen. et sp. n. and Sinochaetodus tri- range is probably 129.7e122.1 Ma (Barremian to early Aptian). dentatus gen. et sp. n.. Their phylogenetic positions are analyzed (Yang et al., 2007) and discussed. The discovery provides further evidence for the Diagnosis. In addition to the diagnosis for the genus, the species can Cretaceous diversification of Hybosoridae. be diagnosed as follows: mesotibia without transverse carinae on outer margin; metatibia with one transverse carinae on outer margin; spurs on the end of tibia prominent, the length of longer 2. Material and methods spur at the end of metatibia 0.58 times as long as metatibia. Description. Body length: 15.1 mm; width: 9.1 mm. Broadly oval, The specimens were examined using a LEICA MZ 12.5 dissecting compact and pilose. microscope and illustrated with the aid of a drawing tube Head. Clypeus finely and closely rugulose, anterior margin straight; attachment. mandible prominent, protruding beyond anterior margin of This study are based on two specimens housed in the fossil in- labrum; maxillary palp three-segmented. Pronotum: Shape para- sect collection of the Key Lab of Insect Evolution & Environmental bolic, 1.9 times as wide as long, notoriously wider than head, widest Changes, the College of Life Sciences, Capital Normal University, near 1/4 to base; anterior margin of pronotum slightly arching, Beijing, China (CNUB; Dong Ren, Curator). lateral sides round; anterior angles are acute, posterior angles Taxon sampling, character states, and a phylogenetic analysis on broadly rounded. Scutellum: Triangular, 1.3 times as wide as long. the phylogenetic positions of the two new genera are provided in Elytron: Shape parabolic, elytra 1.2 times as long as wide medially, supplementary information, Appendix C. 1.1 times as wide as prothorax. Legs: Pro- and mesocoxae close, mesocoxae round; protibia dilated apically, meso- and metatibia 3. Results with long pubes and two spurs at apex; metatibia with one trans- verse carinae on outer margin; mesotibia 2.2 times as long as wide, 3.1. Systematic paleontology metatibia 3.5 times as long as wide; mesotarsal relative length of each segment (base to apex) 6:4:3:6:12. Abdomen: 6-segmented, Order Coleoptera Linnaeus, 1758 apex slightly rounded. Superfamily Scarabaeoidea Latreille, 1802 Genus Sinochaetodus Lu, Bai, Ren and Yang gen. n. Family Hybosoridae Erichson, 1847 (LSIDurn:lsid:zoobank.org:act:8D013AE3-98B4-4250-841A- Genus Sinohybosorus Nie, Bai, Ren and Yang gen. n. B83564AA2B97) (LSIDurn:lsid:zoobank.org:act:44726F8D-77C2-465F-BF50- Type species: Sinochaetodus tridentatus sp. n. 6B0B869AD0EE) Etymology. Sino- (Latin) ¼ from China, Chaetodus is the genus to Type species: Sinohybosorus cheni sp. n. which the new fossil is most similar. Etymology. Sino- (Latin) ¼ from China, Hybosorus is the genus to Diagnosis. Sinochaetodus is similar to Chaetodus Westwood, 1845 which the new fossil is most similar. but differs from the latter by pronotum without areolateocellate, Diagnosis. Sinohybosorus is similar to Hybosorus Macleay, 1819 but meso- and metatibia slender, mesotibia outer margin without differs from the latter by scutellum bigger, the length of elytron longitudinal row of teeth, metatibia outer margin with one longi- 5.3 times as long as scutellum; pronotum widest near 1/4 to base; tudinal row of teeth. Chaetodus has the pronotum with areolateo- legs robust, mesotibia 2.2 times as long as wide, metatibia 3.5 cellate, meso- and metatibia robust, outer margin with two times as long as wide. Hybosorus has the smaller scutellum, the longitudinal rows of teeth. length of elytron at least 15 times as long as scutellum; pronotum widest at base; legs slender, meso- and metatibia at least five Sinochaetodus tridentatus Lu, Bai, Ren and Yang sp. n. (Figs. 3e4) times as long as wide. (LSIDurn:lsid:zoobank.org:act:22E017FB-8CF0-48B8-8BFE- B602BA97D690) Sinohybosorus cheni Nie, Bai, Ren and Yang sp. n. (Figs. 1e2) Holotype. A well preserved almost complete body with elytra, (LSIDurn:lsid:zoobank.org:act:C11EBF53-4724-4F0D-8F6A- registration No. CNU-COL-LB2016002, Yixian Formation, near C83319751D72) Chaomidian Village, Beipiao City, Liaoning Province, China; The Holotype. A well preserved almost complete body with elytra, type specimen is housed in the Key Lab of Insect Evolution & registration No. CNU-COL-LB2016001, Yixian Formation, near Environmental Changes, the College of Life Sciences, Capital Chaomidian Village, Beipiao City, Liaoning Province, China; the type Normal University, Beijing, China (CNUB). specimen is housed in the Key Lab of Insect Evolution & Environ- Etymology. Tridentatus (Latin) ¼ with three teeth, here referring to mental Changes, the College of Life Sciences, Capital Normal Uni- the protibia. versity, Beijing, China (CNUB). Type strata and locality.