Steginoporella neozelanica (Busk 1861)
- Dataset
- Living and fossil Steginoporellidae (Bryozoa: Cheilostomata) from New Zealand
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Bryozoa
- class
- Gymnolaemata
- order
- Cheilostomata
- family
- Steginoporellidae
- genus
- Steginoporella
- species
- Steginoporella neozelanica
description
Redescription. Colony erect, comprising cluster of unbranched columnar stems of varying lengths up to 80 mm, mostly in the range 40 – 60 mm, attached to hard substratum by basal tangle of rootlets. Rootlets forming as prolongations of the frontal cuticle of autozooids no longer possessing opercula; no rootlet pores. Colour in life brownish-orange. Zooids monomorphic, roundly subhexagonal but longer than wide (mean L / W = 1.37), widest at level of median process. Cryptocyst occupying about half length of frontal surface, shelf depressed, flat, densely porous, with a pair of recesses in proximal corners. Opercular opening delimited proximally by acutely triangular opercular pivots and median process, with distolateral ‘ wings’ that do not meet pivots but have narrow, delicate calcareous extension on each side meeting the lateral margin and delineating an irregular transverse opesiule; proximomedial pore longitudinally elongate. Operculum reinforced by distinctive pattern of sclerites, generally comprising a transverse strip (straight or irregular) from which an oblique pair of strips connect to the proximal margin; an I- or H-shaped sclerite occurs between these, sometimes with the crossbar and the top half of the H lacking; a short median vertical sclerite may pass from the mid-distal margin to the transverse sclerite or part or all of it is lacking or is paired. Thickness of sclerites may increase with age of zooid. Polypide with 22 – 24 tentacles. Ancestrula and early astogeny not seen. Measurements. ZL 864 ± 36, 778 – 894 (1, 10); ZW 632 ± 26, 578 – 667 (1, 10); OpL 238 ± 30, 198 – 278 (1, 10); OpW 462 ± 34, 411 – 500 (1, 10).
discussion
Remarks. Steginoporella neozelanica was the first steginoporellid to be described for New Zealand. Its colonies are large, distinctive and common enough on underwater rock faces to be noticed and photographed by divers, who refer to it as the ‘ finger bryozoan’ (Fig. 1 A). The number of stems in a clump can exceed 60; whether or not these are all part of the same genetic individual is not known. It seems likely, insofar as clumps are discrete, but the variation in stem length within a clump suggests the possibility of larval recruitment to established colonies, a hypothesis that needs to be tested genetically. In colonial morphology it is closest to Steginoporella marcusi Livingstone, 1929 (see below), which, however, comprises single stems, not clusters, often has a single bifurcation, and a different pattern of opercular sclerites. Out of the many samples of S. neozelanica that have been examined, only a single branch bifurcation has ever been seen, and it was very short and only at the base of a stem near the rootlets, unlike the distal branching in S. marcusi. Zooids of S. marcusi are, on average, larger than those of S. neozelanica and the median process, while very similar, consistently differs in detail. The reticular sclerites of the operculum of S. marcusi form somewhat of a honeycomb pattern that is closer to that in S. perplexa than to S. neozelanica. Nevertheless, it seems that S. neozelanica and S. marcusi are closely related.
distribution
Distribution. Endemic to New Zealand: Three Kings Islands, Spirits Bay, northeast coast of North Island from North Cape to Bare Island off the coast of central Hawke’s Bay at depths of 6 – 76 m on rock faces. Harmer (1900) reported the species [the ‘ Vincularian form’] from Wanganui, on the West Coast of the lower North Island, but it has never been seen in any of the many NIWA samples from this region, which suggests a possible local extinction. Waters (1887) cited Steganoporella [sic] neozelanica as a fossil in the Hawke’s Bay region of eastern North Island but, since he stated that colonies comprised “ S. neozelanica in the Lepralia - stage ”, it is apparent that he was referring to S. magnifica (see below), of which we also have seen fossil material from this area.
materials_examined
Material examined. Syntype: NHMUK 99.7.1.1530, Busk Collection, ‘ New Zealand’. Other: NHMUK: 98.6.5.2, Napier. NIWA 73096, Stn TAN 1105 / 27; NIWA 75121, Stn TAN 1108 / 179; NIWA 75193, Stn TAN 1108 / 197; NIWA 75364, Stn TAN 1108 / 213; NIWA 75401, Stn TAN 1108 / 217; NIWA 75479, Stn TAN 1108 / 233; NIWA 75496, Stn TAN 1108 / 239; NIWA 101415, Stn Z 15924; NIWA 107197, Stn E 268; NIWA 107200, no data; NIWA 107201, C. A. J. Duffy donation; NIWA 119897, Stn T 254. Plus unregistered (nonseparated) specimens in multispecies samples from NIWA Stations K 796, K 820, K 849, K 851, K 856, K 857, Z 15598, Z 15904, Z 15924, Z 1595, Z 9665, Z 9674, Z 9680, Z 9681, Z 9682, Z 9685, Z 9686, Z 9688, Z 9689, Z 9694, Z 9698, Z 9701, Z 9702, Z 9704, Z 9713, Z 9714, Z 9715, TAN 0906 / 21.