Genus Diaurora Cockerell, 1903

Figs 3A, B, 4, 5

Type species.

Unio auroreus Heude, 1883, by original designation.

Diagnosis.

Shell small size, symmetric, flat, sub-glossy, triangular-ovate to reniform, orangish to brownish, with broken blackish-green rays. Zigzag sculpture present. Posterior ridge absent.

Remarks.

Aurora Simpson, 1900 was originally described as a subgenus of Parreysia based on shell morphology. Simpson (1900) indicated uncertainty regarding the taxonomic placement of Unio auroreus and whether it merited a generic rank. As a result, he provisionally designated it as a new subgenus. Cockerell (1903) renamed Aurora as Diaurora due to the former being a junior homonym of Aurora Ragonot, 1887 ( Insecta: Lepidoptera: Pyralidae) and Aurora Sollas, 1888 ( Porifera: Demospongiae: Ancorinidae). Haas (1924) elevated Diaurora to an independent genus, but this viewpoint was not widely accepted. Wu et al. (1999) recombined Parreysia aurorea as Acuticosta aurorea based on shell morphology and marsupium type. While Diaurora shares some similarities in shell morphology with Acuticosta, it can be differentiated from Acuticosta by its distinct shell shape and the absence of a posterior ridge (Fig. 3).