Taiwanasteridae, Wang, 1984

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 : 155

Taiwanasteridae

This family is here represented by two species in the genus Sinaechinocyamus . The data show that Gregory’ s diverticulum is present in Sinaechinocyamus mai ( Fig. 3f–j ) and Sinaechinocyamus planus . In S. mai , the organ was found to be fully distended with sand up to a test length of 9 mm, while traces of diverticular sand could still be seen in a specimen of 10 mm test length. In 32 out of 34 specimens of S. mai (94 %), sediment was found inside the diverticulum.

Figures

Fig. 3 Absence of Gregory’s diverticulum in the Rolutidae (a–e) as well as presence and shape of the organ in the Taiwanasteridae (f–j) and Echinarachniidae (k–t). The figure shows selected X-ray images. a, b Heliophora orbicularis (15, 46 mm test length); c–e Rotula deciesdigitatus (17, 22, 50 mm); f–j Sinaechinocyamus mai (1.5, 3.5, 6, 6.5, 7.5 mm); k–o