Dyakiidae, Gude & B. B. Woodward, 1921

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 : 101

Family Dyakiidae

Remarks. Dyakiidae was included as a tribe of Ariophantinae (then included in Helicarionidae ) by Baker (1941a); however, Solem (1966) recognised it as a separate subfamily of Helicarionidae . In Hausdorf’s (1998) phylogenetic analysis of the Limacoidea s. l., Dyakiidae appeared as the sister group to Gastrodontoidea and was placed in its own superfamily, Dyakioidea . This treatment was followed by Schileyko (2003a). A phylogenetic and biogeographic analysis of Dyakiidae was also carried out by Hausdorf (1995).

In all of our analyses this group was distinct from Helicarionoidea . It can be defined as follows:

Shell complete. Stimulator present, inserted on the atrium or vagina; stimulator section A 5 with acinose glands, two major lobes present; stimulator section A 2 with dart. Epiphallic retractor caecum and flagellum absent.

Description. Shell complete, wider than 25 mm in diameter. Mantle lobes absent. Sole undivided or tripartite; caudal apparatus formed from curled up sole ( Muratov’s 1999 helicarionid type). Kidney unilobed; minor venation on roof of mantle cavity present. Genital system oviparous; oviduct glandular. Bursa copulatrix inserted on base of stimulator. Capsular gland absent or present. Stimulator present, inserted on atrium or vagina; stimulator section A 5 with acinose glands, two major lobes present; stimulator section A 2 with dart. Penial sheath absent or present; open at distal end. Epiphallic retractor caecum absent; epiphallic flagellum absent. Presence of spermatophore not known.