Phaeostachys schmitzi ( Norman, 1909 ) Norman, 1909

Berning, Björn, 2012, Taxonomic notes on some Cheilostomata (Bryozoa) from Madeira, Zootaxa 3236, pp. 36-54 : 46

Phaeostachys schmitzi ( Norman, 1909) n. comb.

( Figs 19–22 , Table 4)

Schizoporella schmitzi Norman, 1909: 304 , pl. 41, fig. 2.

Material examined. Holotype: NHMUK 1911.10.1.1109, by monotypy, Norman collection, Madeira, encrusting a Glycymeris shell (no further information provided as to exact location or depth).

Description. Colony encrusting, unilaminar, multiserial. Zooids oval to hexagonal, broadest at about mid-distance, separated by shallow grooves. Frontal shield slightly convex, surface finely granular, irregularly perforated by up to 30 round pseudopores that decrease in diameter during ontogeny; occasionally with a low blunt conical umbo proximal to the sinus. Primary orifice about as long as wide, anter comprising about three-quarters of a full circle, delimited from a deeply U-shaped poster by straight horizontal or slightly sloping proximal margins, condyles fairly indistinct, broadest at proximolateral corners and thinning towards edges of the sinus; generally with 6– 7 seven spines around the lateral and distal orificial margin, rarely with 5 or even 4.

Ovicells not observed.

Avicularia adventitious, single or occasionally double, rarely absent, situated in lateral zooecial corner and/or directly suboral, directed proximally or distolaterally; rostrum elongated triangular, crossbar complete, no ligula, proximal uncalcified area semicircular, distal area subcircular.

Ancestrula tatiform, c. 420 x 310 µm, gymnocyst well-developed proximally, opesia comprising about twothirds of total length, surrounded by 10 spines.

ZL ZW OL OW AL AW mean 602 418 169 174 142 78 SD 55 44 8 12 16 8 min. 512 353 156 158 112 67 max. 725 512 182 197 173 93 n 20 20 20 20 13 13

Remarks. Phaeostachys schmitzi is remarkably similar to the type and only other known species in the genus Phaeostachys , P. spinifera ( Johnston, 1847) , which differs only in having a thinner avicularian rostrum and an ancestrula with 12 spines ( Hayward & Ryland 1999: 238). In the absence of ovicells in the type specimen, and owing to the lack of additional colonies for comparison, it is difficult to judge whether these differences represent intra- or interspecific variation, and it could well be that the two forms will have to be synonymised in a future study. In any case, the similarity is remarkable, given that P. spinifera is a cool-temperate species, ranging from Brittany to the Faroe Islands, not documented from warmer regions further south ( Hayward & Ryland 1999) apart from a single record from the north-eastern Adriatic Sea ( Novosel & Pozar-Domac 2001). Therefore, if the Madeiran Phaeostachys population is not anthropogenically introduced, its arrival on the archipelago is likely to have occurred during glacial periods, with this ‘boreal guest’ staying for good.

Figures

FIGURES 19 – 22. Phaeostachys schmitzi (Norman, 1909) n. comb., holotype, NHMUK 1911.10.1.1109. 19, overview of colony; note the presence of a central umbo in some zooids (arrows). 20, ancestrula with intramural bud and mostly damaged periancestrular zooids. 21, autozooids, some with an additional adventitious avicularium. 22, close-up of primary orifice. Scale bars: Fig. 19 = 400 µm; Figs 20, 21 = 100 µm; Fig. 22 = 20 µm.