Powellitheca waipukurensis ( Waters, 1887 ) Waters, 1887

Emanuela Di Martino, Paul D. Taylor, Dennis P. Gordon & Lee Hsiang Liow, 2016, On Powellithecidae fam. nov., a new Pliocene to Recent bryozoan family endemic to New Zealand, with the description of Powellitheca gen. nov. (Bryozoa, Cheilostomata), European Journal of Taxonomy 207, pp. 1-17 : 10-15

Powellitheca waipukurensis ( Waters, 1887) comb. nov.

Figs 4 , 5 A–D, 6, Table 3

Monoporella waipukurensis Waters, 1887: 50 , pl. 6, fig. 11.

Hippoporina ? waipukurensis – Brown 1952: 272, figs 203–204.

Emballotheca waipukurensis – Gordon et al. 2009: 296. — Rust & Gordon 2011: 156.

Material examined

Lectotype

NEW ZEALAND: NHMUK D32522, Mangapanian,?Pliocene, Hawkes Bay, Waipukurau Gorge.

Additional figured material

NEW ZEALAND: NHMUK BZ 7744 and BZ 7745, Nukumaruan, Pleistocene, Nukumaru Limestone, Waiinu Beach; NHMUK D36986, same details as lectotype.

Other material

NEW ZEALAND: NIWA 98228, 15 colonies from Hatuma Quarry, Waipukurau.

Description

Colony large, encrusting, multiserial, unilaminar ( Figs 4 , 5 A, 6A). Ancestrula minimally calcified, comprising a thin rim of granular cryptocystal calcification with the outline shaped as a matryoshka doll, about 250–450 μm long by 250–355 μm wide, budding one distal and two distolateral zooids ( Fig. 6 D–E). First three budded zooids smaller than later ones, about 230–360 μm long by 240–300 μm wide, hexagonal ( Fig. 6 D). Zooids developed from ancestrular buds are irregularly polygonal and angled at 90˚ to 180˚ to encircle the ancestrula ( Fig. 6 D). Later autozooids arranged in well-defined rows, distinct, boundaries marked by very narrow furrows, quadrate to rectangular, generally with squared corners, longer than broad, with a highly variable length/width ratio (mean L/W = 2.23), some appearing squat and others slender ( Figs 5 , 6 A–B). Frontal shield lepralioid, slightly convex, granular, regularly and evenly perforated by 40–50 small, circular pores about 10–15 μm in diameter ( Fig. 6 A–C). Frontal septula not distinguishable, probably because of obliteration by the growth of diagenetic cement. Orifice placed distally, generally broader than long, with the proximal lip gently convex and two tiny condyles placed proximal to the midlateral position ( Fig. 6 F); an imperforate, smooth, scarcely raised peristomial rim lateral and distolateral to the orifice, terminating in a flat, suboral umbo, palette-shaped, often broken and leaving an oval depression ( Figs 5 C–D, 6F). Lyrula and oral spines absent ( Fig. 6 G). Ovicells hyperstomial. Ooecia globular, large, occupying almost the entire frontal shield of the next distal zooid forming the ooecium. Ectooecium membranous. Endooecium calcified, tubercular like the frontal shield, with deep pits and tubercles radially aligned in alternating ridges and furrows, the frontal rim imperforate and smooth, slightly upturned ( Figs 5 A–C, 6C). Primary orifice of fertile zooids larger than that of autozooids, rounded quadrangular, about as long as wide; secondary orifice slit-like with a tongue-shaped, suboral umbo ( Figs 5 A–C, 6C). Avicularia uncommon, adventitious, placed lateral to the orifice or at zooid midlength, usually single, rarely paired, when paired one smaller, semielliptical or 8-shaped with a spatulate, rounded rostrum, distolaterally directed ( Figs 5 C, 6C, F), no crossbar. Kenozooids budded at junctions between colonies growing on same substratum, similar to autozooids in size and in the appearance of the frontal shield but lacking apertures ( Fig. 6 B). Oval, multiporous (at least six pores) septula visible on vertical walls ( Fig. 6 H), about 40 μm long by 20 μm wide. Intramural, reparative budding also observed ( Fig. 6 C).

Remarks

Brown (1952: 272, fig. 204) chose NHMUK D32522 from Waipukurau Gorge as the lectotype of this species. This specimen forms part of the T. Hincks Collection and is accommodated in a cavity slide that was labelled “ Monoporella waipukurensis on Heteropora [sic]” by Eliza Jelly. Jelly traded bryozoans extensively in the late 19th century ( Torrens & Winston 2002: 307–308) and the supposition must be that this particular specimen was used by Waters when describing his new species, then passed on to Jelly who in turn gave it to Hincks. Brown figured (fig. 203) a fertile specimen (D36986; Fig. 5 ) from the same locality and collection to provide details of ooecia, which are lacking in both the lectotype and the Waters’ specimen from Napier housed in the Manchester Museum. Brown (1952, p. 274) questioned the status of the Manchester Museum specimen, describing it as a slide labelled “ Monoporella waipukurensis ” by Waters and referring to it as a “?original syntype ”. As this specimen lacks ovicells, he considered that it was not the specimen figured by Waters (1887, pl. 6, fig. 11), which does have ovicells.

Distribution

This species has been found in the Mangapanian Te Aute Limestone (Pliocene, ~ 3.1 Ma) of Waipukurau Gorge and nearby Hatuma Quarry, Hawkes Bay, and in the Nukumaruan (early Pleistocene) Nukumaru Limestone (~ 2.3–2.0 Ma) and Nukumaru Brown Sand (~ 2.0–1.9 Ma) units of Nukumaru and Waiinu beaches, Wanganui Basin, and Nukumaruan at Petane (trigonometrical station), just north of Napier, Hawkes Bay, New Zealand.

Figures

Fig. 4. Powellitheca waipukurensis (Waters, 1887) comb. nov. NHMUK BZ 7744, Nukumaruan, Pleistocene, Nukumaru Limestone, Waiinu Beach. Two colonies of P. waipukurensis encrusting a bivalve shell, competing with other bryozoan species for space. Note the band of fertile zooids with large, globular ovicells.

Fig. 5. Powellitheca waipukurensis (Waters, 1887) comb. nov. Specimen figured by Brown (1952: fig. 203), NHMUK D 36986, Mangapanian, Early Pliocene, Hawkes Bay, Waipukurau Gorge. A. General view of the colony. B. Group of autozooids and fertile zooids showing the dimorphic orifices. C. Group of zooids with avicularia. D. Autozooids. Scale bars: A = 500 µm; B – C = 200 µm; D = 100 µm.

Fig. 6. Powellitheca waipukurensis (Waters, 1887) comb. nov. Nukumaruan, Pleistocene, Nukumaru Limestone, Waiinu Beach. A – F. NHMUK BZ 7744. A. General view of two colonies encrusting a bivalve shell. B. Fusion of the two colonies shown in A and formation of kenozooids along the encountering edge. C. Group of fertile zooids and autozooids. D. Ancestrula and early ontogeny. E. Close-up of the minimally calcified ancestrula. F. Autozooidal orifice and avicularium. — G – H. NHMUK BZ 7745. G. Internal view of the proximal, convex, orificial rim lacking a lyrula. H. Multiporous septula on the zooidal vertical walls. Scale bars: A = 1 mm; B = 500 µm; C – D = 200 µm; E – F = 100 µm; G – H = 20 µm.

Tables

Table 3. Measurements in microns of Powellitheca waipukurensis (Waters, 1887) comb. nov.

	N (zooids, colonies)	Mean	SD	Min	Max
ZL	22, 4	562	± 50	469	679
ZW	22, 4	248	± 49	182	367
OL	22, 4	113	± 11	94	139
OW	22, 4	142	± 20	114	182
OL*	12, 4	203	± 19	177	203
OW*	12, 4	211	± 14	190	211
OvL	40, 4	406	± 37	339	476
OvW	40, 4	354	± 38	258	429
AvL	12, 4	149	± 17	119	177
AvW	12, 4	102	± 12	84	130