Dartevellopora neozelanica, Gordon & Taylor, 2010

Gordon, Dennis P. & Taylor, Paul D., 2010, New seamount- and ridge-associated cyclostome Bryozoa from New Zealand, Zootaxa 2533 (1), pp. 43-68 : 58

Dartevellopora neozelanica n. sp.

( Fig. 9 A–H )

Material examined. Holotype: NIWA 61252 , from cruise TAN0104, Stn 3, 42°45.48– 42°45.18’S, 179°59.47– 179°59.54’ W, “Graveyard” Seamount, Chatham Rise, 943–1097 m depth, collected 15 April 2001 . Paratypes: NIWA 61253 , from TAN0104/149, 42°43.02’ S, 179°57.60– 179°57.90’ W, “Morgue” Seamount, 903–1162 m depth, collected 18 April 2001 . Other material: TAN0104 Stns 43, 150, 336.

Distribution. “Graveyard Seamount Complex”, north-central Chatham Rise, New Zealand, 750–1181 m.

Etymology. From New Zealand (in contradistinction to the provenance of the type species ― Tierra del Fuego).

Description. Colony erect, up to 3.5 mm high, with an apron-like base, columnar, devoid of zooidal apertures in the column, topped by a capitulum of open zooids that, depending on its width (up to 2.8 mm in diameter), results in a clavate or fungiform shape for the distal half of the colony.

Base of colony comprising a small circular disc (2.91 mm diameter), the lower part of the column smooth or somewhat pedunculate, the remainder generally with short rounded protuberances marking the locations of occluded apertures. All surfaces interior-walled.

Capitulum comprising short autozooidal peristomes in quincunx with kenozooids, the openings of which are of variable diameter depending on the degree of closure by calcification. Autozooids opening more or less around the periphery of the capitulum in well-formed colonies, the apertures circular, 0.10–1.12 mm in diameter. Capitulum surface relatively planar in infertile colonies, more domed in fertile colonies.

Gonozooids 1–3 per colony, produced sequentially, brood chambers ventricose, their surfaces generally with a small, flat, circular depressed area 0.72–1.12 mm in diameter, bordered by a rim, within which is the ooeciopore, 0.09 mm in diameter. Floor of brood chamber smooth.

Ancestrula not seen.

Remarks. The genus is scarcely known. Borg (1944) introduced Dartevellia monotypically for several infertile colonies of a small columnar bryozoan on a gastropod shell from 8 m depth off Ushuaia, Tierra del Fuego, Argentina. Borg’s species is illustrated only by very poor half-tone photographs. They have the general form of the Chatham Rise colonies here attributed to Dartevellopora but, although Borg’s description is comprehensive, the lack of proper illustrations makes some aspects of his description ambiguous. For example, he mentions the column in D. cylindrica as “rising from a Tubulipora -like initial growth” but that the “proximal portion of the peduncle is surrounded by at least two layers of kenozooids, one outside the other” and “the surface of the peduncle” is “marked by numerous longitudinal septal lines.” A kenozooid layer is not externally visible in D. neozelanica , which otherwise conforms to D. cylindrica in the unique colony shape, the capitulum with a relatively small number of autozooids, the occurrence of kenozooids in the capitulum, and the rarity of pseudopores.

Figures

FIGURE 9. Dartevellopora neozelanica n. sp. (TAN0104 Stn 3). A, C, profiles of fertile colonies with brood chambers in capitulum disk; B, infertile colony; D–H, apical views of brood chambers; note the smooth brood-chamber floor in G and H.