Urocyclidae (Van Mol, 1973)

Hyman, Isabel T. & Ponder, Winston F., 2010, A morphological phylogenetic analysis and generic revision of Australian Helicarionidae (Gastropoda: Pulmonata: Stylommatophora), and an assessment of the relationships of the family 2462, Zootaxa 2462 (1), pp. 1-148 : 91

Family Urocyclidae

Remarks. Urocyclidae was created for taxa from Africa ( Simroth 1889) and has often been treated since as an endemic African group (e.g., Baker 1941a; van Goethem 1977). Hausdorf (1998) defined Urocyclidae as containing taxa in which stimulator section A 5 was absent, although noted that the stimulator was missing in some taxa. Since both taxa included in the current study had no stimulator, Hausdorf’s (1998) synapomorphy could not be confirmed. The sample size was too small to allow any comments on urocyclid monophyly.

Schileyko (2002b) pointed out that there are difficulties in interpreting urocyclid taxonomy since the two major revisors ( van Goethem 1977; Van Mol 1968, 1970a,b, 1973) did not cover any common ground but instead focused on separate subsets of taxa. Schileyko (2002b) divided Urocyclidae between subfamilies and tribes of Helicarionidae and Ariophantidae , based primarily on reproductive anatomy.

Winter (2008) recently redescribed the west African helicarionoid genus Thapsia Albers, 1860 and described three new genera. Winter (2008) commented on the difficulties of assigning these taxa to a family, due in part to the paucity of information available about taxa from this region. It is possible that some African species currently assigned to Urocyclidae actually belong to the other helicarionoid families, rendering Urocyclidae polyphyletic ( Bouchet & Rocroi, 2005; Winter, 2008).

Our analysis indicated that the urocyclids can be recognised as a distinct grouping within Helicarionoidea , which is defined as follows:

Shell complete or reduced. Stimulator absent or present; where present, sections A 3, A 4 and A 5 are missing. Some fibres of the penial nerve run through the cerebral ganglion ( Hausdorf 1998). Epiphallic retractor caecum and flagellum absent or present; lime-sac absent ( Trochonanininae ) or present ( Urocyclinae ).

Description. Shell complete, partially reduced or fully internalised. Mantle laps and lobes absent or present, varying in size and degree of fusion. Sole of foot tripartite; caudal apparatus present, formed from curled up sole ( Muratov’s 1999 helicarionid type). Kidney unilobed; minor venation on the roof of the mantle cavity present. Genital system oviparous; oviduct glandular. Bursa copulatrix inserted on vagina. Capsular gland present. Stimulator absent or present; where stimulator is present, stimulator section A 5 (apical gland) is missing; dart and/or papilla in stimulator section A 2 can be absent or present. Penial sheath present; distal end fused to epiphallus. Epiphallic retractor caecum absent or present; epiphallic flagellum absent or present; epiphallic lime-sac present in some Urocyclinae . Spermatophore in form of soft capsule with long hard tailpipe, or in taxa with lime-sac in form of soft-walled tube closed at both ends.