Schizomavella rosae, Reverter-Gil & Souto & Novosel & Tilbrook, 2015

Reverter-Gil, Oscar, Souto, Javier, Novosel, Maja & Tilbrook, Kevin J., 2015, Adriatic species of Schizomavella (Bryozoa: Cheilostomata), Journal of Natural History 50, pp. 281-321 : 293-295

Schizomavella rosae sp. nov.

( Figure 6 ; Table 4)

Schizomavella cornuta: Novosel 2007: 62 (in part), fig. 26F.

Type material

Holotype. CNHM Inv. br. 36: St. 8, Jabuka Shoal (PJ-1), 43°06.060 N, 15°26.210 E, 27 August 2001, 34 m depth, several fragments of one colony on Smittina cervicornis ( Pallas 1766) ( Figure 6 ).

Diagnosis

Primary orifice rounded trapezoidal, its greatest width across the distal quarter; sinus small, quadrate or U-shaped, occupying one quarter of the proximal border; condyles small, smooth, distal edges of which are angled towards the edges of the sinus. Orifice surrounded by a fine, even rim, describing deep, rounded notches in the proximolateral corners. Three to five long, stout, hollow oral spines; avicularium median suboral, small, close to proximal orifice rim and continuous with it.

Etymology

Named in honour of the senior author ’ s mother, Rosa Mª Gil Carnicer.

Description

Colony encrusting, unilaminar, developing as a small irregular crust.

Autozooids in radial series, separated by fine, raised sutures; rectangular to polygonal, slightly convex. Frontal shield nodular, irregularly perforated by five to 11 rounded pores, plus a row of especially conspicuous areolar pores. A smaller pore (occasionally two) on each side of the distal portion of the suboral avicularium.

Primary orifice rounded trapezoidal, slightly wider than long, its greatest width across the distal quarter; sinus small, quadrate or U-shaped, occupying one quarter of the proximal border; condyles small, smooth, distal edges angled towards the edges of the sinus. Orifice surrounded by a fine, even rim, producing deep rounded notches in the proximal corners.

Three to five (usually four) long, stout, hollow, oral spines, frequently broken.

Avicularium median suboral; small, monomorphic; slightly inclined to frontal shield on a small prominence; close to proximal orifice rim and continuous with it; rostrum subrectangular, proximally directed; crossbar complete with a small median columella; the edges of the foramen in the rostral palate with several sharp denticles on the inner edges.

Kenozooids rare; small, irregularly shaped, occupying spaces between autozooids, provided with an avicularium, similar in size, shape, and orientation to those of the autozooids.

Zooid lateral walls with small uniporous septula, placed in rows near the basal wall.

Ovicell not observed. Ancestrula unknown.

Remarks

Schizomavella rosae sp. nov. shows close similarities with two other species of the genus: the Atlantic Schizomavella hondti Reverter-Gil and Fernández-Pulpeiro, 1996 and the Mediterranean Schizomavella triangularis Reverter-Gil and Fernández-Pulpeiro, 1997 .

Schizomavella hondti has an orifice with a much narrower proximal border and a smaller sinus; the condyles are larger, rhomboidal, with faceted surfaces. The suboral avicularium in this species is smaller, oval and lacks a palate; moreover, although it is placed near the sinus it remains unattached to the orificial rim.

Schizomavella triangularis also possesses a suboral avicularium connected with the orificial rim, but it can be distinguished from S. rosae sp. nov. by its roughly triangular primary orifice with its denticulate internal borders, the large condyles extending beyond the edges of the sinus, and the frontal shield perforated by numerous pores.

Schizomavella rosae sp. nov. also shows superficial similarities to S. cornuta , such as the shape of the orifice and their proximal notches, and the Y-shaped avicularian foramen, which was considered by Hayward and McKinney (2002) as characteristic of the latter species. However, S. cornuta produces zooidal orifices that are much wider than long, widest midway, the sinus is wider, and the condyles are oval, with lateral notches and rough distal edge. Finally, S. cornuta produces polymorphic avicularia, which can either be orientated perpendicular to the frontal wall on a suboral umbo or enlarged spatulate, proximally directed and recumbent of the frontal shield, although both are directly in contact with the sinus of the orifice.

Figures

Figure 6. Schizomavella rosae sp. nov. (CNHM Inv. br. 36, holotype, St. 8, Jabuka Shoal). (A) Group of zooids; (B) development of oral spines; (C, D) primary orifices; (E) autozooids and a kenozooid with adventitious avicularium.

Tables

Table 4. Measurements (in mm) of Schizomavella rosae sp. nov. (holotype).

	Mean	SD	Minimum	Maximum	N
Autozooid length	0.504	0.0691	0.397	0.628	16
Autozooid width	0.352	0.0517	0.274	0.456	16
Orifice length	0.106	0.0061	0.095	0.118	16
Orifice width	0.115	0.0050	0.101	0.122	16
Avicularium length	0.061	0.0088	0.037	0.074	16
Avicularium width	0.037	0.0032	0.030	0.045	16

Note: SD, standard deviation; N, number of measurements.