Steginoporella magnifica Harmer, 1900

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 : 349-350

Steginoporella magnifica Harmer, 1900

( Figs 5 , 10–19 , 31–33 )

Membranipora magnilabris: Hutton 1880: 190 . Non Steginoporella magnilabris ( Busk, 1854) .

Steganoporella neozelanica [Lepralia -stage]: Waters 1887: 50, 51. Non Steginoporella neozelanica ( Busk, 1861) .

Steganoporella magnilabris: Hamilton 1898: 195 ; Hutton 1891: 105.

Steganoporella neozelanica var. magnifica Harmer, 1900 (part): 260, 264, pl. 12, fig. 5, pl. 13, fig. 26; Levinsen 1909: 168, pl. 5, fig. 4a–c; Brown 1952: 123, figs 70–71;? Brown 1954: 419.

Steganoporella neozelanica var. typica: Gordon 1967: 52 .

Steginoporella neozelanica var. magnifica: Gordon 1970: 313 , fig. 4 (part); Ryland 1975: 386.

Steganoporella magnifica: Pouyet & David 1979a (part): 570.

Steginoporella magnifica: Pouyet & David 1979b (part): 783, text-fig. 2; Uttley & Bullivant 1972: 25; Gordon 1984 (part): 56; Gordon 1986: 73; Gordon et al. 2009: 290.

Material examined. Lectotype: NHMUK 1899.7 .1.400, Busk Collection , ‘ Tongataboo’ (i.e. Tongatapu Island), Kingdom of Tonga.

Other Recent: NIWA 75440, Stn TAN 1108/233; NIWA 98542, Stn KAH0907/15; NIWA 120076, 122579, Stn M797; NIWA 122574, Stn Z8662; NIWA 122669, Stn B224. Plus unregistered (non-separated) specimens in multispecies samples from NIWA Stations B480, B484, B488, B498, B611, B616, C754, C759, C857, C867, C869, D262, D269, D272, D273, M773, M774, M776, M780, M782, M791, M793, M795, O608, Q686, Z9665, Z9672, Z9676, Z9677, Z9678, Z9679, Z9680, Z9681, Z9684, Z9685, Z9686, Z9687, Z9688, Z9692, Z9694, Z9695, Z9696, Z9697, Z9701, Z9703, Z9705, Z9706, Z9708, Z9710, Z9712, Z9713, Z9715, Z9716 and KWB. NHMUK 2017.7.31.1, RV Munida , 80–100 m, Otago Shelf, South Island.

Fossil: NHMUK BZ3433 , Pliocene or Pleistocene,? Napier ; NHMUK BZ 7840 , Pliocene, Late Opoitian– Waipipian (= Zanclean–Piacenzian ), Whenuataru Tuff , Flowerpot Bay , Pitt Island , Chatham Islands ; IGNS BZ 337 , Pleistocene, Castlecliffian, Tainui Shell Bed , The Pinnacles , Castlecliff , Whanganui.

Redescription (Stn M797). Colony large, encrusting, multiserial, forming circular or irregular sheets 50–60 mm across on rocks and large shells, sometimes multilamellar through self-overgrowth. Colour in life pale brownish beige. Zooids monomorphic, roundly subhexagonal, longer than wide (mean L/W = 1.45), widest at level of median process. Cryptocyst granular-tubercular, occupying about half length, or slightly less, of frontal surface, shelf densely pitted with occluded pseudopores. Opercular opening defined proximally by edge of median process, with reduced ‘wings’ that do not meet lateral margin; proximomedial pore variable, ranging from more or less occluded to quite large. Operculum reinforced on inner side by variable reticulate pattern of sclerites, these generally defining about six peripheral areas surrounding 1–2 central areas. Feeding crown with 24 tentacles. Ancestrula smaller than other zooids but resembling them, deep-bodied, the sides interior-walled and granular; smooth thin margins of frontal cryptocyst on both sides converging and meeting proximally, descending to substratum. First daughter zooid budded laterally, followed near-simultaneously by distolateral pair from ancestrula.

Measurements. Milford Sound, Stn M797: ZL 1128±75, 1009–1233 (1, 10); ZW width 778±73, 678–867 (1, 10); OpL 310±25, 267–350 (1, 10); OpW 499±35, 443–539 (1, 10).

Tongatapu (lectotype): ZL 1106±84, 962–1250 (1, 12); ZW 714±88, 569–816 (1, 12); OpL 426±40, 330–491 (1, 12); OpW 495±46, 368–536 (1, 12).

Whangaroa Harbour (Stn O608): ZL 908±48, 869-989 (1, 5); ZW 610±76, 531–690 (1, 5); OpL 308±13, 295– 327 (1, 5); OpW 472±13, 418–514 (1, 5);

Remarks. Harmer (1900) reported the species as occurring in both Tonga and New Zealand but illustrated only material from southern New Zealand. The epithet ‘ magnifica ’ was adopted by Harmer from a slide of material from Tonga labelled thus by George Busk, who regarded it as a variety of S. neozelanica . Because Busk’s epithet was not mentioned in any of his manuscripts we attribute authorship fully to Harmer. Subsequently Brown (1952) selected a specimen from Tongatapu, the main island of the Kingdom of Tonga, as lectotype of S. magnifica . Notwithstanding the fact that Tonga is tropical and New Zealand is not, our examination of the lectotype reveals no obvious differences from mainland New Zealand populations, which show overlapping within- and betweencolony variations in zooid size and details of the cryptocyst ( Figs 10–19 ). Above, we give key measurements for zooids from three locations—Tonga, northern New Zealand and southern New Zealand. These particular measurements were taken from zooids in the zone of astogenetic repetition and do not necessarily reflect the wider range of within-colony variation. Mean zooid size is greatest in the sample from southern New Zealand but opesia length (not width) is greater in the sample from Tonga.

Steginoporella magnifica is a common species of the lower intertidal and continental shelf, where its unilaminar planar colonies encrust mainly rocks and shells, and occasionally anthropogenic substrata like wood, stainless steel and tins. In some settings, as in current-swept tidal channels and straits, colonies may begin growth on small hard substrata that are occasionally mobile; self-overgrowth can allow multiple layers to form. Superficially, the species is very similar to Steginoporella discors n. sp. (see below), another encruster.

Steginoporella magnifica is also of reasonably common occurrence in the Early Pliocene in the Chatham Islands and in the later Pliocene and Pleistocene in the North Island.

Distribution. Kingdom of Tonga (depth unknown) and New Zealand (Kermadec Ridge, Three Kings Shelf, west coast of North Island, Spirits Bay, both coasts of North Island, Cook Strait, Chatham Rise, Fiordland, Foveaux Strait, Stewart Island; intertidal to 205 m).

Figures

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 10 – 15. Steginoporella magnifica. Tonga, lectotype, NHMUK 1899.7.1.400: 10, intramural buds and a closure (top right); 11, an opesia with the median process. New Zealand, Recent and fossil colonies at same scale as Tongan lectotype, showing variations in the expression of median process: 12, NIWA Stn O 608, Whangaroa Harbour, North Island, showing example of a zooid in which the median process lacks a pore; 13, NHMUK 2017.7. 31.1, RV Munida, 80 – 100 m, Otago Shelf, South Island, showing example in which the median process has a large pore; 14, IGNS BZ 339, Pleistocene, Castlecliffian, Tainui Shell Bed, Castlecliff, Whanganui; 15, NHMUK BZ 3433, Pliocene or Pleistocene,? Napier; opesia proportionately longer and narrower, with the pore in the median process filled by sediment. Scalebars: 10, 1 mm; 11 – 15, 0.2 mm.

FIGURES 16 – 19. Fossil Steginoporella magnifica from New Zealand. 16, NHMUK D 49859, provenance unknown, showing regular patterning of autozooids close to the growing edge; 17 – 18, IGNS BZ 340, Pleistocene, Castlecliffian, Tainui Shell Bed, The Pinnacles, Castlecliff, Whanganui, respectively showing zooids close to the growing edge, and zooids with single or multiple intramural buds; 19, NHMUK BZ 7840, Pliocene, Late Opoitian – Waipipian (= Zanclean – Piacenzian), Whenuataru Tuff, Flowerpot Bay, Pitt Id, Chatham Ids, showing eroded zooids.

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).