Marginoproctus

Ziegler, Alexander, Lenihan, Jennifer, Zachos, Louis G., Faber, Cornelius & Mooi, Rich, 2016, Comparative morphology and phylogenetic significance of Gregory’s diverticulum in sand dollars (Echinoidea: Clypeasteroida), Organisms Diversity & Evolution (New York, N. Y.) 16 (1), pp. 141-166 : 157

Marginoproctus , taxon incertae sedis

Although Gregory’ s diverticulum was reported present in this miniaturized genus by Mooi and Chen (1996), we were unable to duplicate this finding with either radiographic or dissection data from Marginoproctus djakonooi ( Fig. 4a–e ). Therefore, we conclude that Gregory’ s diverticulum is absent in Marginoproctus .

Figures

Fig. 4 Absence of Gregory’s diverticulum in Marginoproctus (a–e) as well as presence and shape of the organ in the Scutellidae (f–o) and Dendrasteridae (p–t). The figure shows selected X-ray images and a photograph of a dissected specimen. a–e Marginoproctus djakonooi (3, 3, 5, 6, 9 mm test length); f–j Scaphechinus griseus (2, 6, 9.5, 35, 36 mm);