Steginoporella marcusi Livingstone, 1929

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 : 350-351

Steginoporella marcusi Livingstone, 1929

( Figs 1B , 3 , 29 )

Steganoporella neozelanica var. marcusi Livingstone, 1929: 68 , text-fig. 2b, pl. 1, figs 9, 12. Steginoporella marcusi: Pouyet & David 1979a: 569 , fig. 3B (part), 571, fig. 4D; Pouyet & David 1979b: 786; Gordon et al. 2009: 290.

Material examined. NIWA 122665, Stn D896; NIWA 122666, Stn TAN1105/42; NIWA 122667, Stn TAN1105/ 60; NIWA 122668, Stn TAN1105/70. Plus unregistered (non-separated) specimens in multispecies samples from NIWA Stations Z9713, TAN0906/154.

Redescription. Colony tall, solitary, columnar, straight, or, if long enough, with a single dichotomy (two specimens with a hint of further possible branching),> 70 mm height, 5 mm diameter but widening at bifurcation, attached to substratum by basal tangle of rootlets. Colour in life brownish-orange. Zooids monomorphic, roundly subhexagonal with convex, rounded lateral margins, longer than wide (mean L/W = 1.68), widest at level of transverse opesiules. Cryptocyst occupying about half length of frontal surface, shelf depressed, weakly concave, densely porous, with pair of pits in proximal corners. Opercular opening delimited proximally by short opercular pivots and median process, with distolateral ‘wings’ that rarely meet pivots but have narrow, delicate calcareous extension on each side meeting lateral margin and delineating an irregular transverse opesiule; proximomedial pore longitudinally elongate. Operculum reinforced on inner side by reticulate pattern of sclerites that define 26–28 areas of similar size, or, if some bars fail to develop, fewer areas (19–21) appear, of variable size. Thickness of sclerites may increase with age of zooid. Polypide, ancestrula and early astogeny not seen.

Measurements. In micrometres: ZL 1110±63, 1022–1211 (1, 10); ZW 661±36, 600–721 (1, 10); OpL 264±19, 233–289 (1, 10); OpW 431±31, 378–467 (1, 10).

Remarks. The similarities and differences between S. marcusi and S. neozelanica have been noted above. Steginoporella marcusi is a rare species, encountered mostly off the far north of North Island, with a single outlier from the eastern Chatham Rise. Collected material has not yet been found attached to a substratum.

Distribution. Endemic to New Zealand: Van Diemen Bank and Three Kings Islands to Tom Bowling Bay and North Cape, with one outlier on eastern Chatham Rise; 61– 129 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 2 – 5. Autozooids of New Zealand Steginoporella (NIWA stations in parentheses). 2, S. neozelanica (TAN 1105 / 27); 3, S. marcusi (D 896); 4, S. perplexa (Z 8662); 5, S. magnifica (M 797). All to same scale (scalebar 1 mm).

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).