LIRONOBIDAE PONDER, 1967

FAMILY LIRONOBIDAE PONDER, 1967 View in CoL

This clade is made up of Merelina and one species attributed to Lironoba . Regrettably only shell characters are known for the New Zealand type species of Lironoba , L. suteri (Hedley, 1904) , and it is by no means certain that the species attributed to Lironoba in this analysis ( L. australis ) is congeneric ( Ponder, 1985a). If L. suteri should prove to belong to a different group, the family name Merelinidae Golikov & Starobogatov, 1975 is available. Species of Merelina and Lironoba australis share some unusual anatomical characters, including a penis with an open seminal groove ( Fig. 4C View Figure 4 ) and a long slit-like opening in the capsule gland ( Fig. 4G View Figure 4 ), features not known in Rissoidae as here recognized.

In most other anatomical features the group resembles the Rissoidae to which they were assigned (in the subfamily Rissoinae ) by Ponder (1985a). Shell features in the group include strong spiral cords, sometimes also with axial ribs, as in Merelina , and usually the protoconch is sculptured with one or more spiral ridges that are gemmate in Merelina . The radula of members of this group has two pairs of basal cusps on the central tooth whereas most rissoids and rissoinids have only one pair.

Another poorly known Australasian genus, Attenuata Hedley, 1918 , may be related to, or included in, this taxon. It shares the gemmate protoconch spirals with Merelina but has a very distinctive radula (Pon- der, 1967, 1985a) with a very wide central tooth lacking basal cusps. It is unknown anatomically.