A new podotreme crab, Necrocarcinus christinae sp. nov., from the Woodbine Formation (Cenomanian) of Texas (USA); the first example of spermathecal apertures in a necrocarcinid brachyuran

Abstract

A new necrocarcinid crab, Necrocarcinus christinae, is described from the Cenomanian deposits (Woodbine Formation) of Irving, Texas. Only a handful of decapod species are known from this formation but N. christinae sp. nov. remarkably represents the third palaeocorystoid crab. The size of the sole specimen known is much larger than usual for the genus; only the larger size of N. woodwardii is more or less comparable, and this species is morphologically most similar to this species. The closely allied genus Elektrocarcinus is reviewed and its diagnostic characters are discussed; its composition is here revised.The sole specimen of Necrocarcinus christinae sp. nov. retains a complete female thoracic sternum, with well-preserved spermathecal apertures. These are the first of such structures known from the Necrocarcinidae; they are conspicuously large compared with similar structures in other palaeocorystoid families such as Cenomanocarcinidae and Palaeocorystidae and likely represent the more basal, plesiomorphic character state. In that respect, this new material contributes to a more complete knowledge of the morphology and diversity of the extinct palaeocorystoid stock.