Stephanollona contracta ( Waters, 1899 )

Berning, Björn, 2012, Taxonomic notes on some Cheilostomata (Bryozoa) from Madeira, Zootaxa 3236, pp. 36-54 : 50-52

Stephanollona contracta ( Waters, 1899)

( Figs 29–32 , Table 6)

Lepralia contracta Waters, 1899: 11 , pl. 3, figs 4–6; Norman 1909: 306, pl. 41, figs 5, 6. Stephanollona contracta: Souto et al. 2010: 18 , fig. 15.

Material examined. Lectotype: MMF 42044a (here designated), the larger colony fragment on a slide; material from Madeira, collected by J. Y. Johnson, colony free of substratum (no further information provided as to exact location or depth). Paralectoype: MMF 42044b, the smaller colony fragment on the same slide as holotype, also free of substratum. Other: NHMUK 2011.9.1.4, Madeira, near Funchal, colony encrusting a piece of coal, Norman collection (no further information provided as to exact location or depth); NHMUK 2011.9.1.5, from the same suite as previous specimen, colony encrusting a piece of coal.

ZL ZW OL OW OvL OvW oAL oAW spAL spAW mean 462 361 129 112 181 243 77 65 265 105 SD 45 37 5 4 14 19 6 3 9 9 min. 411 297 121 103 163 200 67 60 252 89 max. 554 459 137 122 215 273 85 70 285 123 n 20 20 20 20 12 12 12 12 12 12 Remarks. A description of Stephanollona contracta is not given here because the species was only recently redescribed in detail by Souto et al. (2010). However, there are some additional remarks to be made, based on observations of the type-specimen: 1) owing to advanced secondary calcification of the proximal ooecial margin, in ontogenetically older zooids the fenestra in the ooecium may be rather crescentic ( Figs 29, 30 ), whereas the relatively young Portuguese specimen shows only semicircular fenestrae; and 2) the anter may be variable in shape, ranging from a shallow and only slightly concave proximal orificial margin to a more deeply U-shaped anter within the same colony ( Fig. 31 ).

Another issue can be solved here. Souto et al. (2010) mentioned that the type material of S. contracta , which was originally deposited in the MMF, had seemingly been lost. However, for reasons that will be explained in more detail elsewhere, part of a loan of bryozoan specimens by the NHMUK during the 1960s were not returned to Madeira and remained in London (M. Spencer Jones, pers. comm. 2011), among them the types of Saevitella peristomata and Stephanollona contracta described and figured here. After examination of the remaining specimens with the VP SEM in London, the material will finally be returned to the MMF.

As with Plesiocleidochasma porcellanum , Stephanollona contracta is another putative species with a near-circumglobal record (cf. Cook 1964, and references therein), and in need of revision. The specimen from southern Portugal described and figured by Souto et al. (2010) marked the first true record of this species on the European continental shelf.

Figures

FIGURES 29 – 32. Stephanollona contracta (Waters, 1899). 29, surface of mature colony showing several spatulate avicularia (lectotype, MMF 42044 a). 30, close-up of proximal ovicell (paralectotype, MMF 42044 b). 31, zooids at the colony growth margin; note differences in anter shape (arrows) (NHMUK 2011.9.1.4). 32, primary orifice (NHMUK 2011.9.1.4). Scale bars: Fig. 29, 31 = 200 µm; Fig. 30 = 40 µm; Fig. 32 = 20 µm.