Atlantisinidae, Berning, Harmelin & Bader, 2017

Berning, Björn, Harmelin, Jean-Georges & Bader, Beate, 2017, New Cheilostomata (Bryozoa) from NE Atlantic seamounts, islands, and the continental slope: evidence for deep-sea endemism, European Journal of Taxonomy 347, pp. 1-51 : 3-5

Family Atlantisinidae fam. nov.

urn:lsid:zoobank.org:act:17F29C69-ECAC-4D27-A3B6-DE8C96009930

Type genus

Atlantisina gen. nov.

Diagnosis

Colonies encrusting; autozooidal frontal shield umbonuloid, imperforate or pseudoporous. Orifice with condyles, oral spines present. Adventitious and/or interzooidal avicularia present in some taxa. Lateral walls with basal pore-chambers, usually well developed, interzooidal commmunication via a single or few septular pores per neighbouring zooid, budding intrazooidal. Ovicell hyperstomial, ooecium either produced by the zooid distal to the maternal one or of kenozooidal origin, not closed by the operculum, the distal pair of oral spines closely appressed to the sides of the short, tubular ooecial opening; the kenozooidal ooecium may be entirely independent of the substratum and distal zooid, and may be budded from a distinct pore in the maternal zooid’s distal wall; endooecium fully calcified, ectooecium partially calcified. Ancestrula tatiform with extensive opesia; cryptocyst absent.

Remarks

The taxa that are here combined in the Atlantisinidae fam. nov. are morphologcially somewhat similar to, and share some characters with, the families Escharellidae Levinsen, 1909 , Exochellidae Bassler, 1935 and Romancheinidae Jullien, 1888 , while the latter is occasionally considered to include the former two (D.P. Gordon, pers. comm. 2014). However, the new taxa described here share distinct traits, which can be regarded as relatively conservative in an evolutionary sense, that are not present in any of the existing families. Assigning the new genera to the Romancheinidae sensu lato would add yet another set of new characters to this large taxon, and would render the family difficult to define precisely, as well as to delimit it from other lepralielloid families, e.g., the Bryocryptellidae Vigneaux, 1949 .

Characters common to the species in all three genera presented here comprise the partial calcification of the ectooecium and the position of the distalmost pair of spines in maternal zooids, which are so closely appressed to the peristomial aperture of the ooecium as to leave a furrow on each side when the spine is missing. The species usually have extensive lateral walls composed of smooth gymnocyst, and interzooidal communication takes place via one (occasionally two) large septular pores. Moreover, all species share the same ancestrula-type (tatiform with a large opesia that is somewhat constricted in the distal oral part, while the cryptocyst is practically absent).

In contrast, the representative taxa in the Romancheinidae sensu lato are characterised by ancestrulae with a reduced oval or otherwise shaped opesia that is often bounded by an extensive cryptocyst. The ooecium is also structurally different in that the ectooecium is membranous, and the endooecium fuses with the frontal shield of the distal auto- or kenozooid ( Ostrovsky 2013). Both the relatively primitive structure of the ancestrula as well as the morphology of the ooecium in the new taxa may thus suggest that the new family forms a clade basal to the Romancheinidae sensu lato (further discussed below). Genetic studies will be needed to ultimately shed light on the phylogenetic relationships between the new taxa and the Romancheinidae , as well as among the taxa currently placed within the Romancheinidae .