Supercytis gracilis, 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 : 51-52

Supercytis gracilis n. sp.

( Fig. 5 A–D )

Material examined. Holotype: NIWA 61244 , from cruise TAN0104, Stn 130, 42°42.60’ S, 179°58.09’ W, lower northwest slope of “Morgue” Seamount, Chatham Rise, 1067 m depth, collected 17 April 2001 . Paratype: NIWA 61245 , same locality as holotype . Other material: TAN0104 Stns 3, 80, 149, 150, 194, 288, 289, 333, 389, 399.

Distribution. “Graveyard Seamount Complex”, north-central Chatham Rise, New Zealand, 757–1181 m.

Etymology. Latin gracilis , slender, alluding to the form of the colony and the sparsely fascicled branches.

Description. Colony erect, up to 4 mm high and 3.3 mm wide, infundibuliform; the proximal end tapering to 0.26 mm diameter and anchored by a short encrusting base and the expanded distal end with a funnel-like whorl of irregular fascicles of zooidal peristomes; one or more subcolonies may originate from individual fascicles. Colony anchored by a small attachment base to a hard substratum (rocks, encrusting bryozoans), the stem comprising a bundle of long zooidal peristomes that are partly or wholly enveloped in a thin calcareous layer; peristomes with transverse growth lines, all exterior walls pseudoporous, with more pseudopores visible in transparency in transmitted light than externally by SEM. Ancestrular protoecium transversely oval, evident in young colonies, the peristome long, extending the full length of the stem; daughter and later zooids budded behind the peristome, their proximal ends cemented to the substratum and to each other by common calcification. Stem becoming infundibuliform distally as more zooids are budded axially.

Colony centre concave, comprising obliquely polygonal zooidal apertures that face the colony periphery; these can become calcified over. Radial fascicles numbering 6–7, slender, the zooidal peristomes not connate through their length, the terminal portion free with circular aperture 0.10–0.11 mm diameter, some of the more proximal openings with very short apertures that can be calcified over as the colony becomes older.

Brood chamber 0.7–1.11 mm in diameter, occupying much of the colony centre, ventricose, not pierced by zooidal peristomes, its densely pseudoporous exterior-walled surface initially with a clear perimeter that can become less discrete as a layer of thin surface calcification develops across it; ooeciostome 0.33 mm wide, set in the margin of the brood chamber, transversely oval, sometimes adjacent to an autozooidal peristome.

Remarks. The generic and family attributions of this species are uncertain. There are two genera whose species have a similar colony form — Supercytis d’Orbigny, 1853 , with the Late Cretaceous type species S. digitata d’Orbigny, 1853 , and Telopora Canu & Bassler, 1920 , with the Recent type species Supercytis watersi Harmer, 1915 (see Taylor & Grischenko 1999). The major obvious difference is in the brood chamber, which is traversed by zooidal peristomes in Telopora . The New Zealand shallow coastal/shelf species Supercytis lobata ( Tenison-Woods, 1880) has been attributed to Telopora ( Gordon et al. 2009) because, while zooidal peristomes do not open above the brood chamber as in T. watersi , they nevertheless pass through the brood chamber to the level of the roof, where they are sealed. Similarly, Supercytis savii Ramalho, Muricy & Taylor, 2009 from Brazil was attributed to Supercytis by its authors mainly because the gonozooid is simple and not traversed by peristomes; unlike S. digitata , however, the brood chamber in S. savii is inflated, lacking a clear boundary, and apparently located at a branch bifurcation, not in the colony centre. The brood chamber of S. gracilis is more like that of S. digitata in having a clear boundary, and, in all three species, the ooeciopore is against the margin of the brood chamber; that in S. digitata lacks an ooeciostome (raised rim).

Historically, Supercytis was included in the cancellate family Cytididae (d’Orbigny 1853, Harmer 1915, as Cytisidae ; Bassler 1953) but Cytis d’Orbigny, 1854 has a very different colony form and non-feeding surfaces of kenozooids. In contrast, Canu & Bassler (1920) included Supercytis watersi (i.e., Telopora ), in their family Tretocycloeciidae (= Heteroporidae ) (suborder Cerioporina ) — a taxon with which it has little in common. The family attribution of both Supercytis and Telopora remains to be clarified.

Figures

FIGURE 5. Supercytis gracilis n. sp. (TAN0104 Stn 3). A, B, profiles of the same fertile colony; C, surface view of the brood chamber of the colony in A, B; D (TAN0104 Stn 150) brood chamber of a smaller colony.