3D-anatomy and systematics of cocculinid-like limpets (Gastropoda: Cocculiniformia): more data, some corrections, but still an enigma

Abstract

New material and new methodologies substantially widen the anatomical knowledge on cocculinid limpets. We first provide 3D-anatomies of Fedikovella caymanensis and Teuthirostria cancellata based on serial sections. Both species differ in several major points (mainly the gill-type and several features of the alimentary tract) from typical cocculinids, accordingly they are classified in a new clade, Teuthirostriidae fam. nov. Specimens studied by McLean and Harasewych (LA County Mus Contrib Sci 453:1–33, 1995) under “Fedikovella beanii” probably represent another species new to science. Additional investigations of original (type) section series of Cocculina laevis Thiele, 1904 (type species of Paracocculina Haszprunar, 1987) and of Cocculina radiata Thiele, 1904 (type species of Coccocrater Haszprunar, 1987) imply some nomenclatorial revisions: Cocculina cervae Fleming, 1948 is designated as type species of Pedococculina gen. nov. Anatomical characters confirm the subsequent placement of Cocculina viminensis Rocchini, 1990 into Coccopigya Marshall, 1986, whereas the original generic status of the whale-fall inhabitant Cocculina craigsmithi McLean, 1992 is confirmed despite the unusual habitat. The latter species probably has symbiotic bacteria in the midgut gland; if so this might be due to the environmental and feeding conditions at whale cadavers or hydrothermal vents. Contrary to Lepetelloidea, the Cocculiniformia cannot be included in Vetigastropoda. Recent molecular data support a sistergroup relationship of Cocculiniformia with Neomphalida, and we add the phenotypic perspective on this so-called “Neomphaliones”-hypothesis. In particular, more phylogenomic data are needed to specify the position of Cocculinida among the rhipidoglossate Gastropoda.

Integrative taxonomy of a new cocculinid limpet dominating the Aurora Vent Field in the central Arctic ocean

“…Remarks. The position of the copulatory organ at the right side of the oral lappet, the strongly bend posterior oesophagus at the left side of the body, a single pair of epipodial tentacles, reticulate protoconch sculpture, and simple radial teleoconch sculpture without spinose periostracal hair combined to place the present new species in genus Cocculina [22][23][24]. Cocculina aurora n. sp.…”

“…Similar to C. enigmadonta , the anatomy of the alimentary tract in C. aurora n. sp. was not significantly modified from the typical Cocculina formula [22,23].…”

“…Although the tall, cap-like shell morphology of C. aurora n. sp. differs substantially from typical low, flat shells of other species in this clade [24], cocculinid shell form is known to be variable across species and both the radula and the anatomy provide more reliable taxonomic characters [22,23].…”

“…There are currently six described genera in the family: Cocculina, Coccopigya, Coccocracter, Paracocculina, and Macleaniella, distinguishable by shell sculpture and shape, as well as the condition of the copulatory organ and epipodial tentacles [21][22][23][24]. Two genera, Fedikovella and Teuthirostria, were traditionally considered to be cocculinids, but were recently transferred to a new family, Teuthirostriidae, based on anatomical and protoconch characters [23]. The nominal genus of Cocculinidae is Cocculina, containing about 30 named species around the globe, primarily inhabiting sunken wood.…”

“…The majority of the species are associated with organic falls, most commonly with sunken wood, although how they obtain nutrition from these substrates remains debated [18][19][20]. There are currently six described genera in the family: Cocculina, Coccopigya, Coccocracter, Paracocculina, and Macleaniella, distinguishable by shell sculpture and shape, as well as the condition of the copulatory organ and epipodial tentacles [21][22][23][24]. Two genera, Fedikovella and Teuthirostria, were traditionally considered to be cocculinids, but were recently transferred to a new family, Teuthirostriidae, based on anatomical and protoconch characters [23].…”