(Figs 7–12)

Material examined. Holotype: NIWA 46354. Paratype: NIWA 46355. Both types from c. 5 m depth off Siren Rocks, Taputeranga Marine Reserve, Wellington. Collected by Sheryl Miller, 7 October 2007.

Etymology. Alluding to the resemblance of the species to its congener Catenicella elegans.

Description. Colony erect, delicate, dichotomously branching, composed of jointed segments of 1 or 2 brownish zooids. Unizooidal segments 0.42–0.46 mm long and 0.22–0.26 mm wide, widest distally, tapering to proximal joint. Zooidal surface smooth, gymnocystal, with pair of relatively small, longitudinally oval or slit-like pore-chambers (vittae) proximally, each with 2–5 septular pores and facing more or less frontally; a distal pair of oval pore-chambers adjacent to proximal corners of orifice (infrascapular), 1 at the base of each distolateral tubercle or avicularium, facing more or less frontally or slightly laterofrontally. Another much smaller pair of chambers (suprascapular) between the tubercles and joint, facing distally. Orifice high-arched, with broad shallow poster bounded by proximal rim that is frontally convex; a pair of simple condyles near proximolateral corners. Distolateral corners of zooid in form of stout blunt tubercles, one or both of which may house an avicularian chamber; palatal surface distal to cross-bar facing laterally. Bizooidal internodes 0.56–0.65 mm long, distalmost zooid almost parallel-sided; proximal pair of pore-chambers smaller than in unizooidal internodes and displaced closer to orifice. Innermost infrascapular chamber of the proximal zooid of the pair subcircular, displaced towards centre of distal zooid of the pair. Fertile segments bizooidal, 0.63–0.71 mm long; zooid distal to maternal zooid angled slightly frontalward. Ovicell with circular median frontal foramen, and subcrescentic pore-chamber and typically few tiny excavations or pits laterally. Distal zooid of pair with or without aviculiferous tubercles; avicularia of proximal zooid, if present, facing more or less distally.

Remarks. This species closely resembles Catenicella elegans Busk, 1852 in the field, having the same colour and colony form. There are, however, several differences in the zooids and fertile segments ― in C. elegans, the vittae are much longer; the distolateral corners of the zooids do not project distally as blunt tubercles; the innermost infrascapular chamber of bizooidal segments is somewhat triangular and not displaced; the ovicellular vittae are longer and there are more small frontal excavations and pits in the ectooecium.

Catenicella pseudoelegans is so far known only with certainty from the Taputeranga Marine Reserve on the Wellington south coast where it attaches to fucoid seaweeds from the infralittoral fringe to about 15 m depth. A total of seven other described species of Catenicella have been reported (sometimes as Vittaticella) in New Zealand waters (Macken 1958; Powell 1967; Gordon 1984) but not all were illustrated and the repositories of some are not known. Some were infertile and their taxonomic status requires verification.