The Cambrian palaeoscolecidWronascolexfrom the Shipai fauna (Cambrian Series 2, Stage 4) of the Three Gorges area, South China

Abstract

AbstractOur understanding of fossil priapulids, and in particular the palaeoscolecids, is limited owing to the rarity of preserved anterior introverts and a general absence of detailed cuticular ornament preservation in compression material. Here we describeWronascolex yichangensissp. nov. (Cycloneuralia, Palaeoscolecida) on the basis of overall external morphology and distinctive scleritome organization in new compressed material from the Shipai fauna, Cambrian Series 2, Stage 4 in the Three Gorges area of South China. Recurrent fine‐scale features observed inSEManalysis distinguishW. yichangensissp. nov. from other species by its extremely closely spaced annulations, each with two rows ofHadimopanella‐type plates ranging from 37 to 62 μm in diameter but without platelets or microplates, and each plate adorned with a single circle of four to seven nodes and an occasional central node on the upper surface. Since the recent reassignment of some species fromPalaeoscolexintoWronascolex, the latter genus has become a fairly diverse and cosmopolitan genus ranging from Cambrian Stage 4 to Drumian in age. However, knowledge of the sclerite pattern ofWronascolexand its associated microstructure for taxonomic purposes are still poorly understood. Since the origins of the phosphatizedHadimopanella‐type sclerites are apparently quite diverse, evaluating the biodiversity and biostratigraphic utility ofWronascolexis currently problematic.