Steginoporella lineata, Gordon & Voje & Taylor, 2017

Gordon, Dennis P., Voje, Kjetil L. & Taylor, Paul D., 2017, Living and fossil Steginoporellidae (Bryozoa: Cheilostomata) from New Zealand, Zootaxa 4350 (2), pp. 345-362 : 356-357

Steginoporella lineata n. sp.

( Figs 1F , 22, 24–25 , 35–36 )

Etymology. Latin, lineatus, pertaining to a line, alluding to the narrow, linear form of the colony.

Material examined. Holotype: NIWA22945 , TAN0205 /64, 30.162° S, 178.578° W, NW slope of Macauley Seamount , west-central Kermadec Ridge , 22 April 2002, 328 m. Paratypes: NIWA 122577 , same data as for holotype ; NIWA 122578, K795, 33.063° S, 179.567° W, southern Kermadec Ridge , 18 July 1974, 270 m.

Description. Colony small, narrow, linear, not cemented to substratum but attached by sparse rootlets issuing laterally from cuticle of interior-walled colony margin; comprising ribbon-like growths 3–5 zooids across, up to 22 mm long and 3 mm wide. Dried colonies initially light brown, darkening with age, especially the operculum.

Zooids dimorphic. All zooids roundly elongate-rectangular with arcuate distal and proximal margins (mean L/ W = 1.79); lateral margins parallel or slightly converging proximad; widest at level of median process or midlength. Cryptocystal area more than half zooid length, extensive shelf sunken, weakly concave, scattered pseudopores mostly occluded. B-zooids as large as or larger than A-zooids.

Opesial outline of A-zooids with lateral margins widening distad, the arcuate orificial shelf broad; angular articular pivots lacking; median process with distolateral ‘wings’ that do not meet lateral margin; proximomedial foramen of small to moderate size, subrounded. Inner face of operculum smooth, lacking sclerites. Opesial outline of B-zooids somewhat triangular, i.e. with lateral margins converging distad, also with broadly arcuate orificial shelf. Median process as well developed as in A-zooids or with smaller wings. Inner face of mandible with inversely V-shaped sclerites; these can also be clearly seen in frontal view as dark lines.

Polypide not seen. Ancestrula smaller and proportionally narrower than other zooids, tapering proximad, cryptocyst descending to substratum. First daughter zooid budded laterally.

Measurements. In micrometres: ZL 1238±86, 1021–1323 (3, 10); ZW 691±29, 643–744 (3, 10); OpL 201±38, 167–289 (3, 10); OpW 382±60, 221–445 (3, 10); AvL 1292±58, 1200–1389 (4, 10); AvW 746±28, 683–778 (4, 10); AvOpL 254±18, 221–278 (4, 10); AnOpW 467±32, 389–506 (4, 10). AnL 1205; AnW 561.

Remarks. Steginoporella lineata n. sp. is notable as the only species from New Zealand with both A- and Bzooids. The dried mandibles of the B-zooids are darker than those of A-zooids, also indicating pigmentation. The species is unusual in that colonies may attach wholly to a hard substratum, typically basalt, or only partly to a substratum, or not at all, having sparse lateral rootlets.

Distribution. Endemic to New Zealand, central and southern Kermadec Ridge; 270– 328 m.

Figures

FIGURE 1. Six species of Recent New Zealand Steginoporella (NIWA stations in parentheses). A, S. neozelanica (TAN 1105 / 27); B, S. marcusi (respectively from three localities, left to right, D 896, TAN 1105 / 42, TAN 1105 / 60); C, S. perplexa (small colony from Z 15617); D, S. discors n. sp. (TAN 0906); E, S. modesta n. sp. (TAN 0413 / 109); F, S. lineata n. sp. (TAN 0205 / 64). All to same scale (scalebar 25 mm).

FIGURES 20 – 25. Zooids of New Zealand Steginoporella (NIWA stations in parentheses). 20, S. discors n. sp. (Z 9743); 21, 23, S. modesta n. sp., respectively showing autozooids and an ancestrula and daughter zooid (TAN 0413 / 109); 22, 24 – 25, S. lineata n. sp., showing autozooids and larger avicularian B-zooids (TAN 0205 / 64). Figs 20 – 22 at same scale (scalebar 1 mm); scalebars 0.5 mm in figs 23 – 25.

FIGURES 28 – 36. Opercula of New Zealand Steginoporella species showing presence and absence of sclerites on the inner face of the outer layer (localities in parentheses). 28, S. neozelanica (non-NIWA locality, Bare Island, Hawke’s Bay); 29, S. marcusi (D 896); 30, S. perplexa (Stn Z 8662); 31 – 33, S. magnifica, showing variation in sclerites from the same colony (Stn M 797); 34, S. discors n. sp. (Stn Z 9743); 35 – 36, S. lineata n. sp., showing opercula of smaller autozooid and larger avicularian B-zooid (Stn TAN 0205 / 64). All to same scale (scalebar 0.2 mm).