Schizomavella mystacea, 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 : 288-293

Schizomavella mystacea sp. nov.

( Figures 4 , 5 ; Table 3)

Schizomavella auriculata var. cuspidata (Hincks) : Gautier 1962: 135 (in part or whole).

Schizomavella cuspidata: Reverter-Gil and Fernández-Pulpeiro 1996: 267 (in part: only fig. 4F).

Schizomavella cornuta: Novosel 2007: 62 (in part).

? Schizomavella auriculata var. cuspidata: Zabala 1986: 466 , pl. 12, fig. D; Zabala and Maluquer 1988: pl. 16, fig. B.

? Schizomavella cornuta: Hayward and McKinney 2002 : fig. 26D.

Not Schizomavella cornuta: Hayward and McKinney 2002: 57 , fig. 26 A – C; Novosel 2007: 62 (in part).

Not Schizomavella cuspidata: Hayward and Thorpe 1995: 665 , pl. 2; Hayward and Ryland 1999: 286, fig. 131.

Type material

Holotype. CNHM Inv. br. 34: St. 8, Jabuka Shoal (PJ-2), 43°06.060 N, 15°26.210 E, 28 August 2001, 32 m, several fragments on algae ( Figures 4A – C , 5 B – D, F ).

Paratypes. CNHM Inv. br. 35: St. 8, Jabuka Shoal (PJ-2), 43°06.060 N, 15°26.210 E, 28 August 2001, 32 m, two fragments .

MNCN 25.03/3900: Armaçao de Pêra (Algarve, S. Portugal) two ovicellate colonies (marked in red and black) on a stone collected in fishing nets (together with 21 species more; Figures 4D and 5A, E, G ).

NHMUK 2015.3.4.1: St. 11, Biševo (B1-01), 42°57.312 N, 16°00.261 E, 25 September 1998, 30 m.

Other material examined

MNHN 11176 : St. 222, 15 December 1951, Cap Caveaux (Marseille), Gautier Coll .

MNHN 11218 : St. 125, 2 June 1950, Entre Saunet et Carry (Marseille), Gautier Coll .

MNHN IB-2013 – 558 : Cassidaigne Canyon, PU 4 B 2, 230 m. Harmelin Coll . Two dead ovicellate colonies on a shell fragment.

Diagnosis

Primary orifice short, with very conspicuous proximal notches, surrounded by an even gymnocystal rim including the distalmost part of the suboral avicularium; three to five oral spines; subrectangular suboral avicularium, proximally directed, sometimes slightly laterally displaced, with a distalmost calcified ‘ hood ’; palatal foramen Y-shaped; nonovicellate zooids with a projecting arch distal to the orifice, formed by the secondary calcification of the distal/succeeding zooid(s), rarely developing a small avicularium; ovicell imperforate, with a central umbo and three large, elongate pores just above the orifice; ovicellate zooid developing lateral lapets.

Etymology

From Latin mystax (= moustache), alluding to the shape of the proximolateral notches in the primary orifice.

Description

Colony encrusting, unilaminar to multilaminar, developing as small, irregular crusts.

Autozooids rectangular or irregularly polygonal, in radial series, separated by fine, raised sutures; frontal shield nodular, irregularly perforated by 10 – 20 pores, plus a row of conspicuous areolar pores. A smaller obvious pore either side of the suboral avicularium, placed just below the rim of the primary orifice, sometimes partially concealed by secondary calcification. In young, marginal autozooids, the frontal wall is slightly convex, distally raised to form a slight suboral umbo with which the avicularian cystid is associated; in older, more heavily calcified, zooids, the frontal wall thickens until it reaches the same level as the top of the peristome, so flattening the zooid ’ s appearance.

Primary orifice deeply immersed, the poster tilted basalwards in well-calcified zooids; horseshoe-shaped, much wider than long, its greatest width at midlength; median sinus small, U-shaped, occupying one third of the proximal border. Lateral borders of the primary orifice distinctly curved inwards, describing deep, sharp notches in the proximal corners, accentuated by the edges of the thick, broad, triangular condyles which extend medially beyond the bounds of the sinus. Primary orifice surrounded by a smooth, fine and slightly raised rim, which encompasses the distal end of the suboral avicularium. Nonovicellate zooids with a projecting arch distal to the orifice, formed by the secondary calcification of the succeeding zooid, rarely developing a small avicularium ( Figure 5A ). Three to five (usually four) oral spines, as long as an autozooid, but frequently broken. Zooid lateral walls with small uniporous septula, placed in rows near the basal wall.

Avicularium median suboral, just proximal to the sinus and sometimes concealing it, or occasionally slightly displaced laterally; elongate, subrectangular, proximally directed, inclined at an angle or even perpendicular to the plane of the orifice; edge of the rostrum sometimes finely denticulated; complete crossbar with a median columella. The distalmost part of the avicularium (the opesia) is placed within the rim of the primary orifice, and covered by a raised, calcified, opesial ‘ hood ’. Rostrum with Y-shaped palatal foramen, with several sharp denticles on the inner edges.

Ovicell not closed by the zooidal operculum, recumbent on succeeding autozooid, covered by a nodular, imperforate secondary calcification, developing a median prominence, sometimes very acute and pronounced. A small, proximal area, immediately above the aperture, with three (rarely four) rounded or elongate pseudopores, frequently two proximal, horizontally orientated, and one medial, smaller, vertically orientated. Ovicellate zooids developing lateral lappets, extending to the ooecium and continuous with the ovicell outer calcification.

Ancestrula unknown.

Remarks

The set of characters of Schizomavella mystacea sp. nov. outlined above clearly differentiates this species from the others described in herein.

Schizomavella mystacea sp. nov. was first recorded by Gautier (1962) as S. auriculata var. cuspidata and by Reverter-Gil and Fernández-Pulpeiro (1996, in part) as S. cuspidata . As stated above, S. cuspidata was considered a junior synonym of S. cornuta by Hayward and McKinney (2002), who redescribed the species and designated a neotype, a conclusion with which we tentatively agree. Schizomavella mystacea sp. nov., however, differs from the redescription of S. cornuta as well as from the lectotype of S. cuspidata mainly in terms of its primary orifice morphology. The primary orifice in S. mystacea sp. nov. is much wider than long, with extremely marked lateral notches; the larger condyles, extending beyond the edges of the sinus; the development of a smooth, thin, even rim around the primary orifice, including the distalmost part of the avicularium; the projecting proximal arch of autozooids distal to the orifice of infertile zooids; the avicularium variable in length, but never enlarged or spatulate, and with its distalmost portion (opesia) covered by a calcified ‘ hood ’; finally, in well-calcified, ovicellate zooids, the rim of the orifice produces two well-developed lateral lappets ( Figure 5G ). This final character is also seen in the figures by Hayward and McKinney (2002, fig. 4D), Zabala (1986, pl. 12, fig. D), and Zabala and Maluquer (1988, pl. 16, fig. B), but as the primary orifice is not clearly seen in these illustrations we cannot be sure about the identification of the material. Finally, the number of pores in the frontal shield is higher in S. mystacea sp. nov. than in S. cornuta , while its ovicell has three large, elongate pores, against c. five in S. cornuta .

The Atlantic species S. auriculata also often has lateral lappets in ovicellate zooids, though these are less developed than in S. mystacea sp. nov., but it differs in several other characters, most notably the shape of the primary orifice and the orificial condyles.

The Mediterranean species Schizomavella gautieri Reverter-Gil and Fernández- Pulpeiro, 1997 also develops a stout suboral umbo and a very conspicuous rim around the orifice, but this species differs from S. mystacea sp. nov. mainly in the shape of the primary orifice (subquadrate, with distinct shoulders on each side of the sinus), smaller condyles and the absence of proximolateral orificial notches.

In six of the seven S. mystacea sp. nov. colonies studied, most of the zooids are ovicellate. Only in specimen MNHN 11218, a multilaminar colony with zooids chaotically arranged, are ovicells infrequent. In other species of the genus, ovicellate zooids are, in general, more scarcely produced. Non-ovicellate zooids of S. mystacea sp. nov. have a projecting arch distal to the orifice, formed by the secondary calcification of the succeeding zooid(s) ( Figures 4B , 5A ). In material from the Algarve, this projection may rarely develop a small, inner avicularium ( Figure 5A ). This morphology has not been seen in any other European species of Schizomavella .

Besides the Adriatic material, we have identified two colonies of S. mystacea sp. nov. in the Gautier Collection collected from Marseille, a dead colony collected in the Cassidaigne Canyon at 230 m depth, and a colony collected in the Algarve (S. Portugal). Therefore, S. mystacea sp. nov. is present in the western Mediterranean, extending from the Adriatic Sea to the Gulf of Cadiz. It thus follows that S. mystacea sp. nov. may have been recorded in this area previously, perhaps as S. auriculata , with which it has previously been confused (as S. cuspidata ; see Hayward and Thorpe 1995; Reverter-Gil and Fernández-Pulpeiro 1996), or as any of their varieties.

Figures

Figure 4. Schizomavella mystacea sp. nov. (A, B) Ovicellate and non-ovicellate autozooids with variably developed avicularia (CNHM Inv. br. 34, holotype, St. 8, Jabuka Shoal); (C) (same) lateral view of inclined avicularia and the calcified ‘hood’; (D) autozooids with long oral spines (MNCN 25.03/3900, paratype, Algarve).

Figure 5. Schizomavella mystacea sp. nov. (A) Non-ovicellate zooids with a projecting arch distal to the orifice (black arrows), one of them with an inner avicularium (white arrow; MNCN 25.03/ 3900, paratype, Algarve); (B) zooidal orifice with the bases of five spines, operculum and avicularian mandible (CNHM Inv. br. 34, holotype, St. 8, Jabuka Shoal); (C) (same) zooidal orifice showing the broad, triangular condyles, and Y-shaped palatal foramenof the rostrum; (D) (same) primary orifices and avicularia, holotype; (E) primary orifices and avicularia, Algarve (MNCN 25.03/3900, paratype); (F) ovicellate zooids, holotype (CNHM Inv. br. 34, St. 8, Jabuka Shoal); (G) ovicellate zooids, Algarve; note the lateral lappets and the development of the median prominence (MNCN 25.03/3900, paratype).