The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species Colobocephalus costellatus M. Sars, 1870

Abstract

Diaphanidae has traditionally been considered the basal family of the heterobranch gastropod clade Cephalaspidea with 14 species present in Europe ascribed to five genera. The monophyletic status of the family is controversial because of lack of sound synapomorphies. In this paper we present a review of the diversity of Diaphanidae in Europe and give new data on the morphology and anatomy of 50% of the species together with a synopsis of the relevant systematic characters to distinguish between all European species and genera. The rare species Colobocephalus costellatus is redescribed and shown alive for the first time.Further evidence supporting the non-monophyly of Diaphanidae is given; no synapomorphies were found to unite traditional Diaphanidae taxa, but three groups can be recognized: (1) Diaphaninae with genus Diaphana is united by a globose external, thin, and umbilicate shell and radulae with a bilobed rachidian tooth; (2) Toledoniinae, with genera Toledonia and Bogasonia share the presence of a shell with elevated spire and radulae with a unicuspid rachidian tooth; and (3) an unnamed group, with Colobocephalus and Colpodaspis which are the only genera with internal shells, sculptured and globose with short but protruding spires, and radulae lacking rachidian tooth and with smooth hook-shaped lateral teeth.

A new Antarctic heterobranch clade is sister to all other Cephalaspidea (Mollusca: Gastropoda)

“…presents some shared morphological characters to the genera originally assigned to the family Diaphanidae (see Table ). The new family bears a globose shell similar to that of Colpodaspis , Colobocephalus , and some species of the genus Diaphana , although it is internal only in the Colpodaspididae (Ohnheiser & Malaquias ; see Fig. S2a, b) and in N. joani n. sp.…”

“…The genera Colpodaspis M. Sars, 1870, with two nominal species, and the monotypic Colobocephalus M. Sars, 1870 were included into Diaphanidae based on shell characters (Garstang ; Odhner ). Lately, a more accurate description of live specimens of these three species (Brown ; Ohnheiser & Malaquias ), together with phylogenetic analyses, placed both genera in the new family Colpodaspididae Oskars et al . ; far away from Diaphanidae s. s .…”

<p class="HeadingRunIn"><strong>Northeast Pacific benthic shelled sea slugs</strong></p>

“…Chaban (1996) reviewed the family in the northwest Pacific and Arctic oceans. Diaphanid snails are small (typically <5 mm), found from the intertidal zone to abyssal depths (4,500 m) across all ocean basins from the Artic to the Antarctic (Ohnheiser & Malaquias 2014). Species live on soft substrates, algae, bryozoans, and hydroids, but their diet is unknown (Schiøtte 1998).…”

“…Remarks. Schiøtte (1998) and Ohnheiser & Malaquias (2014) reviewed the taxonomic status and diversity of Diaphana.…”

Οικολογικά Πρότυπα Και Πρότυπα Ποικιλότητας Της Ταξοκοινωνίας Των Μαλακίων Σε Ενδιαιτήματα Σκληρού Υποστρώματος Στις Ακτές Της Κρήτης

“…These are: i) Diaphana globosa (Lovén, 1846), reported from Crete by . It has been originally described from Norway and is currently known with certainty from the Atlantic Ocean only (Schiøtte, 1998;Ohnheiser and Malaquias, 2014); ii) Cylichnium africanum (Locard, 1897), first reported from the Mediterranean based on 4 specimens from Crete deepwaters (Janssen, 1989). This species was described from north-west African shores and is widely distributed in the Atlantic Ocean (Bouchet, 1975).…”