Cellaria calculosa, Achilleos & Gordon & Smith, 2020

Achilleos, Katerina, Gordon, Dennis P. & Smith, Abigail M., 2020, Cellaria (Bryozoa, Cheilostomata) from the deep: new species from the southern Zealandian region, Zootaxa 4801 (2), pp. 201-236 : 203

Cellaria calculosa n. sp.

( Fig. 2 )

Cellaria sp. 6: Achilleos et al. 2019: [3–5, 7, 8].

Material examined. Holotype: NIWA 128673 , cruise TAN0307, Stn 79, 49.8105º S, 175.3216º W, subantarctic slope, 887–908 m, collected 2 May 2003 . Paratypes: NIWA 128672 cruise TAN0307, Stn 79, 49.8105º S, 175.3216º W, subantarctic slope, 887–908 m, collected 2 May 2003 .

Etymology. Latin, calx, pebbles, alluding to the pebbly surface of the zooids.

Diagnosis. Colony branching dichotomously. Zooids in whorls of 3–4, their distal rims elevated. Opesia wider than long with beaded distal rim and convex proximal rim with upturned knob-like condyles. Interzooidal avicularia with triangular rostrum and narrow rounded tip; tiny transversely oval opesial foramen.

Description. Colony erect, jointed, flexible, dichotomously branched; colony fragments not exceeding 15 mm in length. Stem sturdy, more or less cylindrical (W, 300–490 μm); slightly narrower close to node.

Zooids somewhat elongate-hexagonal or rhomboidal in cystid outline, longer than wide (ZL, 328–492 μm; ZW, 236–336 μm; ratio 1.5), alternately, arranged in whorls of 3 zooids close to the nodes but increasing to 4 zooids per whorl in the middle part of the internode. Distal rims of zooids elevated, giving irregular profile to stems. Cryptocyst coarsely granular except in most depressed part proximal to opesia. Cryptocyst ridges continuous distally and more or less converging proximally. Opesia wider than long (OpL, 67–86 μm; OpW, 90–117 μm; ratio 0.7), set in the distal end occupying one-third of the total zooid length, beaded distally and smooth proximally; the proximal rim convex, flanked by upturned knob-like condyles.

Avicularia common, interzooidal, smaller than the autozooid, situated distal or distolateral of parent zooid. Rostrum triangular with concave sides and narrowly rounded tip; directed distally or distolaterally. Mandibular pivots horizontal, stout, their inner ends bent distal, typically converging and forming an irregular ligula-like process. Rostral foramen more or less transversely oval; avicularian opesia tiny, oval or a small slit. Cryptocyst triangular extensive, granular. Mandibular areas granular; foramen with a smooth proximal margin (AvCL, 245–312 μm; AvCW, 192–193 μm; ATL, 153–188 μm; ATW, 111–123 μm; AopL, 47–57 μm; AopW, 50–53 μm; RL, 135–176 μm; RW, 111–123 μm).

Ovicells not recorded.

Ancestrula not clearly distinguished. Proximal-most zooids with opesia sometimes partially occluded; frontal surface with 7–8 conspicuous rootlet pores.

Remarks. In the sum of its characters, Cellaria calculosa n. sp. resembles none of its congeners. The avicularium, in particular, while resembling in form the vicarious avicularia of a number of species, differs in being interzooidal. Only two other species have interzooidal avicularia of triangular form— Cellaria moniliorata Rogick, 1956 and Cellaria sagittula Hayward & Ryland, 1993 —but in both cases autozooids are whorled and the narrower avicularia have weakly developed or no mandibular pivots.

Because the avicularia in C. calculosa n. sp. are not vicarious, it is germane to compare the species with taxa attributed to Paracellaria Moyano, 1969 . Paracellaria elephantina Hayward & Thorpe, 1989 from the South Atlantic has similar autozooids but the avicularia are smaller and directed proximolaterally. Paracellaria elizabethae Branch & Hayward, 2005 from South Indian Ocean has similar avicularia, but the cryptocyst ridges are short and non-converging proximally (in contrast with C. calculosa n. sp., in which they converge).

Distribution. Subantarctic slope east of Bollons Seamount, New Zealand, 887–908 m depth.

Figures

FIGURE 2. Cellaria calculosa n. sp., TAN307/79. A. Internode with autozooids and avicularia. B. Opesia with condyles. C. Interzooidal avicularium. D. Distal tip of internode with rootlet pores and avicularium. E. Proximal end of internode with paired avicularia and autozooids with well-developed rootlet pores. Scale bars: A, D, 500 μm; B, C, 100 μm; E, 300 μm.