Breoganipora bicanalifera, 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 : 442-444

Breoganipora bicanalifera n. sp.

( Figs 99–107 , Table 18 )

Material examined. Holotype: MNCN 25.03/3967, locality DR09. Paratypes: MNCN 25.03/3968, locality DR09; MNCN 25.03/3969, locality DR04; MNCN 25.03/3970, 3971, locality V01; MNHN IB- 2013-631, 632, 633, locality DW117; OLL 2015/914, 915, locality DW117; OLL 2015/916, locality DR04; SMF 40.021, 40.022, locality VH-97-315; SMF 40.023, locality VH-97-65B.

Etymology. Latin canalis, channel, alluding to the two conspicuous channels formed in the peristome.

Description. Colonies consist of an encrusting biserial part producing an erect, rigid, delicate, non-branching stem, at least 1.2 cm high, cylindrical in cross-section, between c. 1 mm (tip) to 1.5 mm (basal part) in diameter. Autozooids arranged in 4–5 alternating series in stem, their orifices opening all around, zooidal peristomes in proximal parts not as prominent owing to secondary calcification during ontogeny.

The biserial encrusting part may bifurcate and is composed of alternating zooids; these large, elongatepolygonal, widest usually at midlength, separated by suture between slightly raised ridges; frontal shield slightly convex, with numerous evenly distributed pseudopores, each encircled by low indistinct rim, shield surface distally rising abruptly to form tall peristome with flaring aperture, hence proximolateral part of peristome formed by frontal shield, with suture and raised ridge separating it from distal part formed by vertical extension of distolateral vertical wall; lateral vertical walls well developed, with one or more large uniporous septula per neighbouring zooid. Inner proximal side of peristome with star-shaped flat central tooth, aligned almost perpendicular to opercular plane, its denticulate edges laterally fused with several vertically aligned lateral denticles that form a pair of ridges on internal peristomial surface, this fusion resulting in formation of paired longitudinal channels for water passage to and from ascus. Primary orifice seen only in developing zooids, with short blunt condyles and broad, shallow concave proximal margin; no oral spines.

Avicularia adventitious, dimorphic; a single small avicularium positioned terminally inside peristome on top of central tooth in every zooid; frontal area of avicularium at acute angle to zooidal frontal plane, rostrum with parallel sides proximally and widening distally, with broad, immersed cryptocystal shelf and distal edge equipped with several small teeth, palatal foramen oval, separated from slit-like postmandibular opesia by complete and relatively thick crossbar with short stout columella, distolateral mandibular edge with narrow finely toothed, downpointing fringe; 2 areolar pores associated with formation of avicularium visible in proximolateral peristome.

Spatulate avicularia observed in erect portion of two colonies, situated at distolateral zooidal margin at base of peristome, directed proximally, at slightly acute angle to frontal shield, i.e. distally raised, rostrum broadly spatulate, palate with broad, flat, immersed shelf narrowing proximally, palatal foramen semielliptical, occupying about half length of rostrum, postmandibular opesia triangular, crossbar complete but relatively slender with tiny columella.

SD, standard deviation; N, number of measurements Ovicell hyperstomial, peristomial, not closed by zooidal operculum. Oooecium formed by distal autozooid, calcified ectooecium with numerous pseudopores of varied size and shape, lateral areas covered by imperforate secondary calcification produced by surrounding zooids (2 lateral, 1 distal) during ontogeny, sutures on raised ridges demarcating contributions of different zooids.

Ancestrula with frontal shield and peristome identical to autozooid but smaller and oval in outline, vertical walls already differentiated and well developed, with several lateral and distal uniporous septula; first autozooid budding distally, second-generation zooid formed lateral to and in direct contact with ancestrula and first zooid, producing first biserial vine; budding in other directions may proceed during later stages from ancestrula.

Remarks. Together with the erect-rigid colonies of Tessaradoma boreale and Porella biserialis , those of Breoganipora bicanalifera n. sp. comprise the most conspicuous part of the bryozoan fauna of the Galicia Bank. Characteristic of this species is the absence of branching in the erect part, which forms a single stem that is either straight or bent at various angles. Ovicells and the spatulate avicularia are formed only in this erect part.

Colonies were recorded from 17 stations between 685 and 1697 m depth.

Figures

FIGURES 99 – 103. Breoganipora bicanalifera n. sp.: 99, encrusting part of colony (MNCN 25.03 / 3969); 100, erect part of colony (SMF 40.022); 101 – 103, consecutive stages of peristome growth (MNHN IB- 2013 - 631, MNCN 25.03 / 3970).

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).

Tables

TABLE 18. Measurements (in mm) of Breoganipora bicanalifera n. sp.

	Mean	SD	Minimum	Maximum	N
Autozooid length	1.080	0.1488	0.816	1.382	28
Autozooid width	0.520	0.0931	0.349	0.729	28
Spatulate avicularium length	0.247	0.0205	0.232	0.261	2
Spatulate avicularium width	0.153	0.0049	0.149	0.156	2
Ooecium length	0.304	0.0339	0.280	0.328	2
Ooecium width	0.381	0.0262	0.362	0.399	2
Ancestrula length	0.625				1
Ancestrulawidth	0.370				1