Fenestrulina littoralis, Gordon, 2009

Gordon, Dennis P., 2009, New bryozoan taxa from a new marine conservation area in New Zealand, with a checklist of Bryozoa from Greater Cook Strait, Zootaxa 1987, pp. 39-60 : 44-46

Fenestrulina littoralis n. sp.

( Figs 13–15 )

Fenestrulina sp. Gordon 1968: 3 et seq.

Fenestrulina malusii var. thyreophora: Gordon 1970: 307 et seq.; Gordon 1971a: 342; Gordon 1971b: 453. Non Busk 1857.

Fenestrulina ? disjuncta: Gordon 1980: 2 et seq., fig. 4D.

Fenestrulina cf. disjuncta: Gordon 1989: 62 , pl. 34A, B. Non Hincks, 1885.

Material examined. Holotype: NIWA 46356 . Paratypes: NIWA 46357 , 46358 . All types from Echinoderm Reef, Goat Island Bay , Leigh, collected D.P. Gordon, February 1977 .

Etymology. Alluding to the species’ solely intertidal distribution.

Description. Colony encrusting, hyaline, circular, attaining c. 22 mm diameter (380 mm 2, comprising c. 1280 zooids). Zooids 0.39 (periancestrular) – 0.46 mm long and 0.23 (periancestrular) – 0.37 mm wide. Lepralioid frontal shield translucent; a single row of areolar pores around margin and between orifice and ascopore; these pores simple in zooids at colony margin, becoming largely or completely occluded by radii and associated calcification in mature and neanic zooids; radii of pores mostly comprise 3 or 4 short struts that together support tiny subcircular ring in centre. Orifice transversely D-shaped, 0.08 (periancestrular) – 0.11 mm wide, bordered by 4 unbranched oral spines that are basally articulated; a reticulated pore between each pair of oral-spine bases. Ascopore crescentic, slightly elevated; bordered on its proximal side by distinctive crest-like umbo that is a shallow V or transverse. Ovicell occupying entire frontal shield of distal zooid up to rim of ascopore, supplanting umbo; ovicellular endooecial calcification typically slightly irregular, with low apical ridge around its summit, distal margin of ovicell with series of small foramina inside rim; an oral spine remains on each side of maternal orifice. Three relatively large basal pore-chambers in distal half of zooid, each with long transverse opening. Ancestrula tatiform, with 11 spines around opesia.

Remarks. Fenestrulina littoralis is possibly widely distributed around North Island shores but it is known with certainty only from Goat Island Bay in the Cape Rodney to Okakari Point Marine Reserve (“Leigh Marine Reserve”), Northland, Tatarimaka and Oaonui, Taranaki, and the Taputeranga Marine Reserve on the Wellington South coast. Gordon (1968) made numerous observations on this species (attributed to Fenestrulina malusii var. thryeophora ) at Goat Island Bay where it is abundant. So long as it is always submerged, the species can come a long way up the shore, such that colonies can be found under rocks in runnels and rock pools within a metre or so of a beach. Colony astogeny and zooidal budding were described in detail by Gordon (1971a, b). Gordon (1970) described reproduction in this species. The minimum colony size in which embryos (coloured strong orange-yellow) were observed was 80 zooids. Peak production of embryos is November through March in the Leigh area; during this period, almost all colonies above 25 mm 2 in area contained embryos, which were found in about 25% of zooids on average. The ancestrular lophophore has 10 or 11 tentacles; that of autozooids 10–13.

Nine other described species of Fenestrulina are known from New Zealand waters ( Gordon 1984, 1989). Fenestrulina littoralis is distinguished from all of them in the sum of its characters, in particular the distinctive and persistent umbo on the frontal shield and the crest on the ovicell. A very similar congener in the marine reserve is F. disjuncta ( Hincks, 1885) . Zooids are similarly translucent but the ascopore, though set in a raised area, is not associated with a proximal umbo and the ovicell is smooth. Zooids are slightly disjunct, with small gaps at the corners, and the proximal pair of oral spines is sometimes forked. A species from the Kermadec Ridge attributed by Gordon (1984) to F. disjuncta has instead 5 or 6 spines, the orifice is more high-arched, and the ovicell is more elongate; it requires a new name.

Figures

FIGURES 13–15. Fenestrulina littoralis n. sp. 13, Ovicelled and non-ovicelled zooids; notice the distinctive crest on the frontal shield and the ovicells; note also that the proximal pair of oral spines in one zooid is forked. 14, Zooids at the colony margin showing pore-chambers; 15, Distal end of an autozooid showing orificial condyles and the double sets of radiated pores between each pair of spine bases. Scale bars: Figs 13–15 = 100 µm.