Schizomavella

Souto, Javier, Reverter-Gil, Oscar & Ostrovsky, Andrew N., 2014, New species of Bryozoa from Madeira associated with rhodoliths, Zootaxa 3795 (2), pp. 135-151 : 144-145

Schizomavella sp.

( Figs 22–25 ; Table 4 )

Material examined. MNCN –25.03/3865: 32º38’30.67’’N 16º49’47.49’’W, 18 m, April 2011, on rhodolith.

Description. Colony encrusting, unilaminar, developing as an irregular subcircular crust. Autozooids in radial series, separated by fine, raised sutures; rectangular to polygonal, slightly convex. Frontal shield nodular, irregularly perforated by 6–12 large, rounded pseudopores and two lateral rows of marginal areolar pores. Suboral avicularium with a small pore on each side. Primary orifice circular, as long as wide; sinus large, U-shaped, occupying more than half of proximal border; condyles small, oval, smooth, reaching edges of sinus and difficult to see. Oral spines long, stout, 2–3, even 4, present only in early ontogeny. Orifice surrounded laterally and proximally by smooth, wide gymnocystal rim incorporating a medial suboral avicularium, occasionally slightly displaced laterally. Avicularia small, monomorphic, inclined at an angle on a small prominence. Rostrum elongate, oval-triangular, directed proximally. Palatal foramen large; crossbar complete, with very small columella. Small opesia of avicularium with raised triangular ‘hood’. Zooids with uniporous septula in vertical walls, placed in rows parallel to basal wall. Ovicells absent in colony examined. Ancestrula unknown.

SD, Standard deviation; N, number of measurements.

Remarks. Schizomavella is a speciose genus with about 36 Recent species reported from all over the world. About ten species are present in the NE Atlantic, another six are supposedly distributed in the Atlanto- Mediterranean region, and other seven species are reportedly Mediterranean endemics.

None of them has an avicularian opesia with a raised triangular rim. Some species have a smooth gymnocystal rim surrounding the zooidal orifice and median suboral avicularium. Among them, Schizomavella cristata ( Hincks, 1879) and S. subsolana Hayward & McKinney, 2002 have a triangular suboral avicularium. In S. fischeri ( Jullien, 1882) the orifice has an arch of 5–7 stout articulated spines and the smooth frontal shield is perforated by a few small pseudopores. In S. auriculata ( Hassall, 1842) the orifice is characteristically drop-shaped and the condyles are sharply cusped. Two cryptic species, S. sarniensis Hayward & Thorpe, 1995 and S. grandiporosa Canu & Bassler, 1925 , recently discussed by Souto et al. (2013), differ from Schizomavella sp. in not only lacking the elevated avicularian rim but in having a more quadrangular orifice, with the gymnocystal rim forming two marked ‘corners’ proximolaterally. They also have a shallower sinus, larger condyles (distally toothed in S. sarniensis ) and a shorter avicularium. In these two latter species the frontal shield becomes prickly in later ontogeny, with the large pseudopores deeply immersed, a character that cannot be seen in our single colony of Schizomavella sp.

As we have a single colony of Schizomavella sp., we cannot study possible variations like changes of the frontal shield with increasing calcification, or the polymorphism of avicularia, if existing; even more, ovicells are lacking. We therefore refrain from giving a specific attribution at present.

In spite of this, we believe that the characters available allow differentiating our colony from the rest of the known species of Schizomavella in the Atlantic-Mediterranean region. Only three species of this genus were previously reported from Madeira— Schizomavella discoidea ( Busk, 1859b) , S. auriculata and S. noronhai ( Norman, 1909) (see Busk 1859b; Hincks 1880; Norman 1909; Berning 2012). Furthermore, Norman (1909) indicated that some specimens of S. auriculata belonged to var. ochracea , which is now considered a separate species, placed in the genus Stephanotheca ( Reverter-Gil et al. 2012) . All of these species clearly differ from Schizomavella sp. However, taking into account the misunderstandings surrounding the identity of S. auriculata until its redescription by Hayward & Thorpe (1995), it is likely that some previous records of this species from Madeira actually correspond to Schizomavella sp.

Figures

FIGURES 22 – 25. Schizomavella sp. (MNCN 25.03 / 3865); 22, general view of the colony; 23, general view of autozooids; 24, primary orifices surrounded by a rim, and the suboral avicularia with elevated distal rims; 25, unbleached zooids with oral spines intact.

Tables

TABLE 4. Measurements (in mm) of Schizomavella sp.

	Mean	SD	Minimum	Maximum	N
Autozooid length	0.436	0.0208	0.413	0.469	6
Autozooid width	0.373	0.0722	0.255	0.440	6
Orifice length	0.095	0.0121	0.073	0.104	6
Orifice width	0.100	0.0049	0.090	0.103	6