Pickworthiidae and Aqabarellidae New Family (Caenogastropoda, Mollusca) of Aqaba, Jordan: Their Larval Shells and Remarks about Their Evolution and Relation

Abstract

Among small sized gastropods found in Aqaba (Jordan), Sansonia occurs relatively common with Sansonia cebuana which is recognized from the the fringing reef near the Marine Biological Station at Aqaba, while Mecoliotia and Chrystella are rare. Mecoliotia aqabaensis n. sp and Chrystella shinaqi n. sp are described with the later resembling Chrystella finckhi. They are compared with other members of the Pickworthiidae, of which a new species of Discrevina from Indonesia is described. A species of Aqabarella new genus resembles in shape of its teleoconch members of the Pickworthiidae but its protoconch is distinct in ornament of the larval shell and shape of the aperture and it is placed in it own family, Aqabarellidae. Aqabarella urdunensis is relatively more common than the rare Aqabarella pulchella. Similar larval shells are found in Vanikoridae, Planaxidae and Cerithiidae, those of Littorinidae and Rissoidae are more distinct and all of them differ from those of the Aqabarellidae, while some ancient small species from the Triassic tropical Tethys had a similar protoconch.