Telson morphology of Leanchoiliidae (Arthropoda: Megacheira) highlighted by a new Leanchoilia from the Cambrian Chengjiang biota

Abstract

HE, YY., CONG, PY., LIU, Y., EDGECOMBE, GD., HOU, XG., May 2017. Telson morphology of Leanchoiliidae (Arthropoda: Megacheira) highlighted by a new Leanchoilia from the Cambrian Chengjiang biota. Alcheringa 41, 581–589. ISSN 0311-5518.Despite being a dominant group in both the Burgess Shale and the Chengjiang biota, diversity of the family Leanchoiliidae mostly consists of monotypic genera, with one genus, Leanchoilia, however, being represented by multiple species from several Cambrian Konservat-Lagerstätten. Here we distinguish a new species of this genus from hundreds of specimens formerly assigned to the Chengjiang species Leanchoilia illecebrosa, and establish its affinity within Leanchoilia by morphology of the telson (distally pointed and fringed with spines), a widely used diagnostic character at the generic level in Leanchoiliidae. The new species, Leanchoilia obesa sp. nov., is distinguished from other species of Leanchoilia by an oval outline of the dorsal exoskeleton and a telson with a long basal region and long spines. The new species is also distinguishable from other species of Leanchoilia by sharing some distinct characters of other leanchoiliid genera such as the wide body shape of Oestokerkus and Yawunik, and tiny serrations on the spinose projection of the great appendages of Yawunik. The mosaic combination of characters at the generic and specific levels prompted a re-evaluation of telson morphology as a diagnostic character in Leanchoiliidae. A new descriptive model of the leanchoiliid telson is based on the development of Leanchoilia obesa, inferred by comparing larval, juvenile and adult specimens. The result reveals that the leanchoiliid telson is a complex morphological unit and a source of diagnostic characters at both the generic and specific levels.Yu-Yang He [heyuyang850604@126.com], Pei-Yun Cong [cong@ynu.edu.cn], Yu Liu [zac.liu@126.com], Xian-Guang Hou* [xghou@ynu.edu.cn] Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, PR China; Pei-Yun Cong [p.cong@nhm.ac.uk], Gregory D. Edgecombe [g.edgecombe@nhm.ac.uk] Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.