Halysestheria Zhang & Chen

LI, GANG, 2021, Taxonomy of the clam shrimp Halysestheriidae (Diplostraca: Spinicaudata) from the Upper Cretaceous Nenjiang Formation in central Dayangshu Basin of eastern Inner Mongolia, northeastern China, Palaeoentomology 4 (2), pp. 156-164 : 158

Genus Halysestheria Zhang & Chen in Zhang et al., 1976 emend.

Type species. Halysestheria biformis Zhang & Chen in Zhang et al., 1976, OD, from the Upper Cretaceous First Member of the Nenjiang Formation of Jilin, northeastern China.

Emended diagnosis. Carapace moderate in size; elliptical, oval, circular or subquadrate in outline; umbo anterior or subcentral; growth lines with serrated lower margins; growth bands in umbonal area of the carapace ornamented by long radial lirae that are relatively widely spaced with an intercalated fine reticulation; those on ventral part of carapace ornamented by dense radial lirae that are separated by cross-bars to form chain-like ornament, which appears as radially aligned, discontinuous, short, fine ridges on the external mould ( Li et al., 2009).

Locality and horizon. Heilongjiang and Jilin provinces, Inner Mongolia, northeastern China, First Member of the Nenjiang Formation; Yunnan Province, southwest China, the Luojumei Member (the lowest member) of the Jiangdihe Formation; upper Santonian.

Remarks. Intheoriginaldescriptionof Halysestheria, Zhang & Chen (in Zhang et al., 1976) overlooked the puncta on growth bands and the serration along the lower margins of growth lines, which were first seen by Li (2005) in specimens of Halysestheria yui ( Chang, 1957) from the Upper Cretaceous Taipinglinchang Formation along the Heilongjiang river in northern Heilongjiang Province. These features were also discovered in specimens from the First Member of the Upper Cretaceous Nenjiang Formation in Yaojia, Jilin Province ( Li et al., 2009).