Breoganipora, Souto, Javier, Berning, Björn & Ostrovsky, Andrew N., 2016

Souto, Javier, Berning, Björn & Ostrovsky, Andrew N., 2016, Systematics and diversity of deep-water Cheilostomata (Bryozoa) from Galicia Bank (NE Atlantic), Zootaxa 4067 (4), pp. 401-459 : 441-442

Genus Breoganipora n. gen.

Type species: Breoganipora bicanalifera n. sp.

Diagnosis. Colony erect, rigid, formed from a biserial encrusting runner. Frontal shield lepralioid, uniformly pseudoporous; basal pore-chambers present, communication via uniporous septula. Primary orifice round, with condyles and concave proximal margin, oral spines absent. Peristome well developed, its proximal and lateral walls formed by the frontal shield, its distal portion by the distal vertical wall; proximal part of peristome with broad peristomial tooth that merges laterally with a pair of short peristomial ridges to form a pair of proximolateral compensation channels (peristomial spiramina) between these structures.

Avicularia adventitious, dimorphic; a single suboral avicularium positioned terminally in peristome, directly associated with and on top of central tooth; a spatulate avicularium occasionally present on zooidal surface near its distolateral margin.

Ovicells hyperstomial, peristomial (opening into peristome). Ectooecium with pseudopores.

Ancestrula similar to autozooids but smaller.

Etymology. Named after the mythical King of Galicia and purported ancestor of the Gaels, Breogán, in conjunction with - pora, a typical ending of bryozoan generic names alluding to the porous frontal shield. Gender feminine.

Remarks. A new genus is established here for an erect smittinid species that lacks a lyrula associated with the primary orifice. Instead it develops a long peristome with a central tooth fusing with a pair of peristomial ridges. Moreover, the ancestrula in the new species is similar to, albeit slightly smaller than, an autozooid in morphology ( Fig. 107 ), whereas in the other smittinid genera it is tatiform. The remaining characters are in accordance with the existing diagnosis of the family Smittinidae (e.g. Gordon 1984, p. 90; Hayward & Ryland 1999, p. 250). The frontal shield in the new taxon is lepralioid and uniformly pseudoporous, condyles are present whereas oral spines are absent, an adventitious avicularium is incorporated terminally in the peristome, spatulate frontal avicularia are occasionally present and the ovicell is typical for smittinids, i.e. with a calcified ectooecium bearing numerous pseudopores.

Whereas the zooids are superficially similar to Smittina species, the orifice in Breoganipora reveals the most distinct differences. The archetypical orificial denticle (lyrula) in smittinids is usually produced from a fold in the proximal gymnocystal margin of the primary orifice (Soule & Soule 1972, fig. 14), and is positioned directly above the operculum (cf. Berning et al. 2014, fig. 2). In the new taxon from Galicia Bank, on the other hand, the proximal orificial margin is broadly concave and has no such structure. Whether the peristomial tooth has moved away from the orifice and upwards within the peristome, and is thus homologous to the smittinid orificial lyrula is difficult to tell at present. Similarities in the formation of this structure and the association with the avicularium, however, suggest that this may be the case.

The large, central, peristomial tooth in Breoganipora is also formed of gymnocystal calfication although it is positioned at about mid-distance in the peristome. Although its shape differs drastically from the true smittinid lyrula by forming a broad, star-shaped and vertically aligned structure with a flat distal surface, it may fulfil the same function. It seems to be in reach of the opened operculum to keep it and the tentacles from obstructing the proximal peristomial margin during tentacle eversion and, particularly, retraction (see Berning et al. 2014). Water compensation during this process takes place via two proximolateral channels formed by the merging of the lateral processes of the central tooth with two proximolateral peristomial ridges. Similar ridge-and-channel structures are present in many other smittinid species that form a considerable peristome, e.g. Smittina kukuiula Soule & Soule, 1973 (their figs 11E, F) and Parasmittina spp. (Berning et al. 2014, figs 7B, 8A).

The adventitious avicularium, which is usually positioned suborally in Smittina species, is incorporated terminally into the proximal peristomial margin in Breoganipora . The mode of formation of the avicularium is, again, similar in the new taxon and some Smittina species. The fold of the proximal orificial margin, which forms the smittinid lyrula, and the walls of the suboral avicularian cystid are continuous. The avicularium thus forms subsequent to, and is situated directly on top of, the proximal part of the lyrula. This close association between lyrula and suboral avicularium can be observed in, for example, Smittina bella (Busk, 1860) (see Hayward & Ryland 1999, fig. 115D), or S. kukuiula (Soule & Soule, 1973, fig. 11F). The process of formation of the peristomial tooth and avicularium in Breoganipora is identical, in the same locus of the peristome.

In contrast, the autozooid-like ancestrula in the new taxon ( Fig. 109 ) is distinctly different from the ones hitherto known in smittinid species. The genera Smittina (cf. Hayward & Ryland 1999, fig. 113C), Smittoidea (cf. Hayward & Ryland 1999, fig. 118D), and Parasmittina Osburn, 1952 (cf. Tilbrook 2006, 148) all have simple tatiform ancestrulae with a variably developed cryptocystal shelf.

Figures

FIGURES 104 – 107. Breoganipora bicanalifera n. sp.: 104, autozooid with peristomial and latero-oral avicularia (SMF 40.022); 105, 106, autozooids with ovicells (SMF 40.021, 40.022); 107, ancestrula, with flared aviculiferous peristome (SMF 40.023).

FIGURES 108 – 113. Placidoporella insperata: 108, holotype specimen (light microscopy); 109, general view of colony (MNCN 25.03 / 3974); 110, 111, autozooids with ovicells (MNCN 25.03 / 3974); 112, general view of autozooid (MNCN 25.03 / 3975); 113, interior view of frontal shield.