Schizomavella aff. linearis ( Hassall, 1841 )

Ramalho, Laís V., Rodríguez-Aporta, Raquel & Gofas, Serge, 2022, Preliminary account on the bryozoans of the Alboran platform (Western Mediterranean), with description of two new species, Zootaxa 5094 (1), pp. 53-91 : 76

Schizomavella aff. linearis ( Hassall, 1841)

( Fig. 11 )

aff. Schizomavella linearis: Reverter-Gil et al. 2015: 27 , fig. 11c–e

Material examined. MNCN 25.03/4309 : BV12, 112– 120 m; coll. UMA; two living and one dead fragments encrusting a polychaete tube and a shell fragment; MNCN 25.03/4310 : BV15, 96 m; coll. UMA; one dead fragment on shell.

Description. Colony encrusting ( Fig. 11A ). Zooids longer than wide [L 358–428–539 (N 6, SD 63), W 225– 272–320 μm (N 8, SD 37)], very variable in size, flat, separated by distinct grooves, with frontal shield irregularly perforated by some circular pores ( Fig. 11A ). Orifice circular [L 60–81–91 (N 9, SD 9), W 84–93–103 μm (N 9, SD 5)] with a small U-shaped sinus, and frequently bearing three distal spines ( Fig. 11B ). Suboral avicularium triangular, placed on a large umbo, with serrated rostrum directed upwards ( Fig. 11C ). Ovicell recumbent, smooth, broader than long [L 145–174–191 (N 5, SD 19), W 191–224–250 μm (N 6, SD 27)]; ooecial surface with a frontal line of pores irregularly shaped and variable in size, sometimes forming an arch ( Fig. 11D ). Ancestrula not observed.

Remarks. Reverter-Gil et al. (2015) have separated Schizomavella linearis into three morphotypes (“typical”, “ hastiformis ” and “ pseudolinearis ”). The “ pseudolinearis ” morphotype has a longer than wide primary orifice and large avicularia, often distally oriented instead of medially as it occurs in the “typical” morphotype. Specimens from the Alboran platform are more similar to the “ hastiformis ” morphotype, due to the single suboral avicularium placed on a large, conical umbo proximal to the sinus. Despite the similar morphology, the Alboran specimens are smaller compared to the Adriatic material figured by Reverter-Gil et al. (2015) (zooids: L 400–583, W 285–504 μm; orifice: L 95–1222, W 110–142 μm; ovicell: L 218–239, W 244–266 μm).

This Alboran morphotype is also similar to Schizomavella (Schizomavella) hastata (Hincks, 1862) in having a suboral avicularium but differs in the shape of the orifice morphology, which in the latter species is characterised by a broad and shallow sinus ( Hayward & Thorpe 1995; Reverter-Gil et al. 2015).

Figures

FIGURE 11. Schizomavella (Schizomavella) aff. linearis (Hassall, 1841) (MNCN 25.03/4310). A. General view of a colony part showing fertile and infertile zooids. B. Detail view of the orifice. C. Detail of a suboral avicularium on the suboral umbo base, showing serrated rostrum. D. Detail of the distal part a fertile zooid showing a large ovicell with a proximal line of large pseudopores. Scale bars: A, 300 µm; B, 40 µm; C, 60 µm; D, 100 µm.