Schizotheca serratimargo ( Hincks, 1886 )

Reverter-Gil, Oscar & Fernández-Pulpeiro, Eugenio, 2007, Species of genus Schizotheca Hincks (Bryozoa, Cheilostomata) described in the Atlantic-Mediterranean region, with notes on some species of Parasmittina Osburn, Journal of Natural History 41 (29 - 32), pp. 1929-1953 : 1943-1944

Schizotheca serratimargo ( Hincks, 1886)

Schizoporella serratimargo Hincks 1886, p 268 , Plate 10, Figure 6 .

Schizotheca serratimargo (Hincks) : Zabala 1986, p 535, Figure 190, Plate 17, Figures C–F; Zabala and Maluquer 1988, p 150, Figures 393, 394, Plate 22, Figures E, F; McKinney 1989, p 35 –48, Plate 1–3; Hayward and McKinney 2002, p 98, Figures 45A–H, 46.

Not Schizotheca serratimargo (Hincks) : Canu and Bassler 1925, p 48.

Material examined

MNHN-12866: Corfu. MNHN-(Paléontologie): Adriatic. NHM-1899.5.1.280: Adriatic. Co-type. NHM-1899.5.1.1088: Adriatic. Part of type. NHM-1996.2.14.1: English Channel ? MM-5371: Golfo di Taranto. MM-5372: Golfo di Taranto. MM-5373: Golfo di Taranto. MM-5374: Golfo di Taranto. MM-8192: Reggio , Calabria. Pliocene. MM- 8193: Messina. MM-8194: Rametto , Sicily. Pliocene. MM-8195: Messina, Sicily .

Remarks

Schizotheca serratimargo is characterized by erect bilaminar colonies with flat branches; the autozooids have a prominent periorbital region (which does not form an actual peristome) that masks a primary orifice, which has a semielliptical finely denticulated anter and concave poster with median sinus. Each zooid bears a triangular, inconstant avicularium, whereas the vicarious avicularia, similar to the adventitious avicularia in structure but larger, are generally situated at the lateral extreme ends of the branches and on the axils of the dichotomies; the vicarious avicularium is three times the size of the adventitious avicularium. The ovicell has a wide proximal fissure.

Schizotheca serratimargo appears to be a fundamentally Mediterranean species, from where it has been cited by different authors. It is abundant in the western Mediterranean and in the Adriatic Sea, extending at least to Corfu. Only two prior reports place this species in the Atlantic.

Canu and Bassler (1925) cited the species from the Atlantic coast of Morocco. However, these authors ( Canu and Bassler 1925, p 48) indicated that the appearance of the zoaria of S. serratimargo may vary, and they may be ‘‘encroûtantes, rampantes, unilamellaires, plurilamellaires et libres, à deux lamelles adossées’’. However, other authors such as Hincks (1886), Gautier (1962), and Hayward and McKinney (2002) indicated that the zoarium of this species is erect and branched, with flat, bilaminar branches; McKinney (1989) indicated the presence of an eschariform portion in a colony collected from the Adriatic. The opinion of Canu and Bassler (1925) on the variability of this species appears to be due to erroneous identifications; we have examined material identified by Canu as S. serratimargo and have found that, with the exception of one sample, from the Adriatic, the material actually corresponds to S. tuberigera and S. aviculifera . Although we were not able to locate all of the original material, we believe that the report of S. serratimargo in the Moroccan Atlantic by Canu and Bassler (1925) should not be considered as valid. In fact, Gautier (1962, p 225) noted this Moroccan citation with a ‘‘?’’.

Schizotheca serratimargo has also been reported from the English Channel by Hayward and Ryland (1999). However, Dr P. J. Hayward has informed us (personal communication, December 2005) that the colony, currently deposited in the Natural History Museum, London, with registration number 1996.2.14.1, had been part of the old exhibition collection at the NHM, and was only labelled ‘‘English Channel’’. As Dr Hayward could not be certain that it was actually from the Channel, the species was excluded from the Synopsis ( Hayward and Ryland 1999).

Figures

Figure 6. Schizotheca aviculifera. (A) Group of zooids (MNHN-14754); (B) view in perspective, showing the position of adventitious avicularia (MNHN-14748); (C) two ovicellate zooids, one of them with three spines (right) (MNHN-14748); (D) two orifices, showing poorly developed proximal teeth, and condyles with wavy distal edge (MNHN-14754); (E) orifice with well-developed proximal teeth (MNHN-14748); (F) a vicarious avicularium, showing Y-shaped foramen (MNHN-14754).