Powellitheca labiosa, Emanuela Di Martino, Paul D. Taylor, Dennis P. Gordon & Lee Hsiang Liow, 2016

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 : 8-10

Powellitheca labiosa gen. et sp. nov.

urn:lsid:zoobank.org:act:081F29FC-4C82-4F0D-A537-1AC61EE8E93B

Fig. 3 A–F, Table 2

Diagnosis

Colony encrusting. Zooids polygonal, arranged in well-defined rows. Frontal shield markedly convex, regularly and evenly perforated, smooth. Small, frontal, multiporous septula at the distolateral and proximolateral zooidal corner. Lateral zooidal communications through small multiporous septula visible on the vertical walls. Orifice with a weakly convex proximal lip and two small latero-proximally placed condyles; lyrula and oral spines absent. Primary orifice hidden by a flat, imperforate, finely granular, projection of the peristome present in both ovicelled zooids and autozooids. Ooecium large, globular, occupying most of the frontal shield of the next distal zooid, porous and granular. Avicularia absent.

Etymology

The name of the species derives from the Latin adjective labiosus, -a, -um meaning ‘with a large lip’, and refers to the flat, labrum-like projection of the peristome covering the primary orifice.

Material examined

Holotype

NEW ZEALAND: NIWA 11828, Recent, 29 Mar. 2011, South Maria ridge, NE of Three King Islands, NIWA Station TAN 1105/53, 33˚57.5’ S, 171˚47.7’ E–33˚57.6’ S, 171˚47.6’ E, 107– 171 m.

Paratypes

NEW ZEALAND: NIWA 98229, 98230, same data as for holotype.

Description

Colony encrusting, multiserial, unilaminar ( Fig. 3 A, D). Maximum colony size about 4 mm long by 2–4 mm wide, fan-shaped. Ancestrula not observed. Zooids arranged in well-defined rows, distinct, boundaries marked by thin furrows, polygonal, longer than broad (mean L/W = 1.36). Frontal shield lepralioid, markedly convex, smooth, regularly and evenly perforated by 30–40 small, circular pseudopores, about 20–35 μm in diameter, sometimes funnel-shaped ( Fig. 3 C). Small, multiporous frontal septula, bearing three very small (about 5 μm wide) semicircular pores, placed at distolateral and proximolateral zooidal corners ( Fig. 3 C) in both ovicellate and non-ovicellate zooids. Orifice of autozooids placed distally, generally broader than long, with the proximal lip weakly convex and two small, proximolaterally placed condyles ( Fig. 3 B). A large, flat, imperforate, finely granular, projection of the peristome hides the orifice in both autozooids and maternal zooids ( Fig. 3 A); lyrula and oral spines absent ( Fig. 3 B). Ovicells hyperstomial. Ooecia globular, large, occupying almost the entire frontal shield of the next distal zooid forming the ooecium. Ectooecium uncalcified. Endooecium granular with deep oval and round pits that are smaller (15–20 μm in diameter) and more numerous than pseudopores of the frontal shield ( Fig. 3 A). Primary orifice of fertile zooids larger than that of autozooids, rounded quadrangular, slightly broader than long ( Fig. 3 E–F). Avicularia absent. Multiporous septula small, about 30–35 μm long by 20–25 μm wide, very distant to each other, bearing two to four tiny pores visible in lateral vertical walls ( Fig. 3 D).

Remarks

This species is similar to Powellitheca terranovae gen. et sp. nov. and P. waipukurensis comb. nov. (see description below) in having a convex, porous frontal shield with small, multiporous frontal septula at the distolateral and proximolateral zooidal corners (these cannot be seen in studied fossils of P. waipukurensis comb. nov.), large, globular, porous and granular ooecia, dimorphic orifices with a convex proximal lip and tiny proximolateral condyles, and oval, multiporous septula on the vertical lateral walls. It differs from P. terranovae gen. et sp. nov. and P. waipukurensis comb. nov. (see description below) in having a well-developed, labrum-like projection of the peristome, and also in having a smooth, non-granular frontal shield with larger pseudopores. The septula in vertical walls are fewer and much smaller with a reduced number of pores, circular in P. terranovae gen. et sp. nov., but semicircular in P. labiosa gen. et sp. nov. In addition, P. labiosa gen. et sp. nov. lacks a lyrula and avicularia.

Distribution

This species is known only from the South Maria ridge, NE of the Three King Islands.

Figures

Fig. 3. Powellitheca labiosa gen. et sp. nov. NIWA 98320 (A – C, E – F), 98229 (D), Recent, Three King Islands, New Zealand. A. Group of fertile zooids and autozooids. B. Tilted view of the primary orifice of an autozooid. Note the lack of a lyrula. C. Close-up of the frontal, multiporous septula on the distolateral corners and the funnel-shaped pseudopores on the frontal shield. D. Lateral, multiporous septula on the zooidal vertical walls. E – F. Tilted view of the orifice of fertile zooids. Scale bars: A = 500 µm; B – C = 100 µm; D = 200 µm; E = 250 µm; F = 150 µm.

Tables

Table 2. Measurements in microns of Powellitheca labiosa gen. et sp. nov.

	N (zooids, colonies)	Mean	SD	Min Max
ZL	20, 4	594	± 53	500 722
ZW	20, 4	438	± 112	311 678
OL	10, 4	124	± 16	103 158
OW	17, 4	218	± 24	170 256
OL*	3, 2	218	± 17	200 234
OW*	4, 2	269	± 21	249 289
OvL	8, 2	473	± 64	333 533
OvW	8, 2	461	± 24	443 500