On Powellithecidae fam . nov . , a new Pliocene to Recent bryozoan family endemic to New Zealand , with the description of Powellitheca gen . nov . ( Bryozoa , Cheilostomata )

A new cheilostome bryozoan genus, Powellitheca gen. nov., is erected here for three species from New Zealand, one of which has been previously assigned to Emballotheca Levinsen, 1909, but which differ significantly from the Australian type species of Emballotheca, E. quadrata (MacGillivray, 1880). Notably, whereas Emballotheca has a cormidial orifice (i.e., formed by numerous neighbouring zooids), and lepralielliform ooecia, the orifice of Powellitheca gen. nov. is formed by single zooids and ooecia are of the microporelliform type. The introduction of a new family, Powellithecidae fam. nov., becomes necessary because of the nonconformity of Powellitheca gen. nov. with other known families having microporelliform ooecia. In addition to the Recent type species Powellitheca terranovae gen. et sp. nov., one other new Recent species, P. labiosa gen. et sp. nov., and a Plio-Pleistocene fossil species, Monoporella waipukurensis Waters, 1887, are assigned to the new genus.


Introduction
Since its first description by Waters (1887) as Monoporella waipukurensis Waters, 1887, the common New Zealand Plio-Pleistocene species currently known as Emballotheca waipukurensis has caused problems for taxonomists, who have placed it in various genera, always with a degree of uncertainty.Brown (1952) excluded the species from Monoporella Hincks, 1881, as defined by Harmer (1926), but had difficulties in choosing an alternative genus, thus assigning it to "Hippoporina?"Neviani, 1895, pending the availability of better material to confirm his identification.Powell (1967) found, for the first time, several infertile specimens of what seemed to be the same species in Recent material obtained by the 'Terra Nova' Expedition in 1910.He discussed Brown's tentative assignment of M. waipukurensis to Hippoporina, noting that the dimorphic orifices, gigantic ooecia and randomly occurring lateral avicularia were features associated with Emballotheca Levinsen, 1909.Although Powell noted that the New Zealand species was clearly related to the Australian type species of Emballotheca, E. quadrata (MacGillivray, 1880), he observed some significant differences between the two taxa in the development of condyles and the arrangement of avicularia on the fertile zooids, as well as discrepancies among fossil and modern specimens with regards to the presence/absence of the lyrula and suboral mucro and in the size of colonies.
Images obtained by Scanning Electron Microscopy (SEM) of a Recent specimen of Emballotheca quadrata in the Zoological Collection of the Natural History Museum, London (NHMUK) have allowed us to investigate further the differences between E. quadrata and ostensibly congeneric species from New Zealand, leading to the introduction of the new genus, Powellitheca gen.nov., for the New Zealand species.Furthermore, comparison of SEM images of fossil and present-day specimens assigned to E. waipukurensis confirm the morphological differences first pointed out by Powell (1967).We consider the dissimilarity to be sufficient to justify the proposal of a new species for Recent material, P. terranovae gen.et sp.nov., which is chosen as the type species of Powellitheca gen.nov.A second new Recent species of Powellitheca gen.nov., P. labiosa gen.et sp.nov., is described from northern New Zealand.As Powellitheca gen.nov.does not conform to any of the other five families with microporelliform ooecial structure, the new family Powellithecidae fam.nov. is also introduced here.

Material and methods
This study is based on both fossil and Recent material from New Zealand.Fossil specimens of Powellitheca waipukurensis comb.nov.were collected from the Pleistocene Nukumaru Limestone by one of us (PDT) in March 1996 at Waiinu Beach, west of Wanganui in the North Island of New Zealand.Recent material of P. terranovae gen.et sp.nov.was collected on 2 Dec. 1981, using a rock dredge in Stephens Hole, Cook Strait, at NIWA's New Zealand Oceanographic Institute (NZOI) Station Q686 (40˚41.3'S, 174˚03.8'E), at a depth of 205 m.Both fossil and Recent colonies are commonly found encrusting mollusc or brachiopod shells.Four specimens of the new species P. labiosa gen.et sp.nov.were collected on 29 Mar.2011 by epibenthic sled, South Maria ridge, NE of Three Kings Islands, at NIWA Station TAN1105/53 (33˚57.5'S, 171˚47.7'E -33˚57.6'S, 171˚47.6'E), at 107-171 m depth, as an epibiont of the erect cheilostome bryozoan Malakosaria sinclairii (Busk, 1857), partly wrapping around the host branch.
The fossil specimens used in this study are deposited in the palaeontological collections of the NHMUK, while the Recent ones are housed in the NIWA Invertebrate Collection of the National Institute of Water and Atmospheric Research in Wellington.
European Journal of Taxonomy 207: 1-17 (2016) Uncoated specimens were studied and imaged using a LEO 1455VP SEM at the NHMUK and a Hitachi TM3000 Tabletop SEM at NIWA.Linear measurements were made using optical eyepiece micrometers and from SEM images using the image processing ImageJ.They are given as the total number of measurements made (N), mean in microns plus/minus standard deviation (SD), and observed range (Min and Max).

Diagnosis
See genus diagnosis below.

Remarks
Powellithecidae fam.nov. is erected to accommodate the new genus Powellitheca gen.nov., characterised by a unique suite of morphological characters when compared with all the known families sharing the same microporelliform ooecial structure.The microporelliform ooecium consists of an uncalcified ectooecium and a calcified endooecium separated by a narrow coelomic space in communication with the hypostegal coelom of the distal autozooid, and has been found only in the lepraliomorph families Microporellidae Hincks, 1879, Pacificincolidae Liu & Liu, 1999, Schizoporellidae Jullien, 1883, Myriaporidae Gray, 1824and Porinidae d'Orbigny, 1852(Ostrovsky 2013).Powellitheca gen.nov.cannot be accommodated in any of these families.It lacks the ascopore typical of Microporellidae and the small heterozooid (avicularium or kenozooid) placed between the orifice and the umbo seen in Pacificincolidae.In Schizoporellidae the orifice has well-defined condyles separating a distinct anter from a small sinus, while the orifice in Powellitheca gen.nov. is dimorphic, condyles are faint and a sinus is lacking.An orifice with sinus and condyles also characterises Myriaporidae from which Powellitheca gen.nov.further differs in having multiporous instead of uniporous septula.Porinidae typically have erect colonies, a primary orifice with a well-defined sinus, a well-developed aviculiferous peristome, and a short frontal spiramen.

Diagnosis
Colony encrusting, with zooids arranged in well-defined longitudinal rows.Zooids with convex, lepralioid frontal shield, regularly and evenly perforated.Lateral zooidal communication through small number of multiporous septula in vertical walls.Orifice dimorphic, wider in maternal zooids.Primary orifice with convex proximal rim and small condyles; not cormidial.Suboral umbo and lyrula present or absent; oral spines lacking.Ovicells hyperstomial.Ooecia of the microporelliform type, large, globular, occupying most of the frontal shield of the next distal zooid.Ectooecium uncalcified.Endooecium thick, granular with deep oval and round pits.Avicularia present or absent, uncommon when present.

Etymology
Named after Neil A. Powell who first described Recent specimens now attributed to this genus in the 'Terra Nova' Collection from the Three Kings Islands area, northern tip of New Zealand.

Remarks
The new genus Powellitheca gen.nov. is introduced for three species of cheilostomes from New Zealand, one of which was previously placed in the Australian genus Emballotheca.After comparing these species with a specimen of the type species of Emballotheca, E. quadrata (Fig. 1), it is clear that they differ in several respects, particularly with regard to the morphology of the orifice, ooecium and avicularia.Although both Emballotheca and Powellitheca gen.nov.have enlarged orifices in maternal zooids and a similar orificial shape with a convex proximal lip, Powellitheca gen.nov.lacks the cormidial orifice seen in Emballotheca, as well as the long and robust condyles with very characteristic downwardly directed, scaled tips (Fig. 1B-C).Ovicells in Emballotheca are hyperstomial and cleithral.The ooecium is of the lepralielliform type, large, formed by the next distal zooid and occupying its entire frontal shield.The globular ectooecium is calcified, thick-walled, with numerous oval and round pseudopores, in most cases covered by the secondary calcification formed by the four or five distal and distolateral neighboring zooids and separated by thin raised sutures (Fig. 1A, D).Secondary calcification corresponds structurally to the zooidal frontal shield and bears pseudopores that are coincident in position with those of the ectooecium.The endooecium is thin and uncalcified (A. Ostrovsky, pers. comm. 2016).Although Powellitheca gen.nov.also has hyperstomial ovicells and the ooecium is similarly large and granular, the ooecia are totally different as they have an uncalcified ectooecium and a calcified endooecium typical of the microporelliform type.
Avicularia in the type species of Emballotheca have a complete crossbar and are directed proximally and towards the midline of the autozooid (Fig. 1B, D-E), whereas in Powellitheca gen.nov., when present, they have an incomplete crossbar with short condyles and are distally and outwardly directed.In E. quadrata, avicularia occur constantly paired in female zooids (Fig. 1A, D), but in Powellitheca gen.nov.they are uncommon and less regularly placed.Another difference concerns the arrangement of zooidal communication pores in the lateral walls, with numerous, small, oval pore chamber windows in Emballotheca (Fig. 1E), but only a few large and consequently more distantly spaced multiporous septula in Powellitheca gen.nov.

Diagnosis
Colony encrusting.Zooids rectangular, arranged in well-defined rows.Frontal shield convex, regularly and evenly perforated, apart from a narrow peristomial area lacking pores, granular.Small, frontal, multiporous septula at the distolateral and proximolateral corners of the zooids.Lateral zooidal communications through multiporous septula visible on the vertical walls.Orifice with a convex proximal lip and two small, lateroproximally placed condyles, bearing an anvil-shaped median lyrula directed downwards and not visible in frontal view.Oral spines absent.Ooecium large, globular, occupying most of the frontal shield of the next distal zooid, porous and granular with the same texture as the frontal shield.Avicularia uncommon, single or paired, with short condyles and tapered rounded rostrum distolaterally directed.

Etymology
Named after the 'Terra Nova' Expedition, the source of several specimens of this species described initially by Powell (1967).

Remarks
Originally included in the 'Emballotheca waipukurensis group' together with the Plio-Pleistocene P. waipukurensis comb.nov.(see description below), the Recent specimens now assigned to P. terranovae

Distribution
This species is known from the Cook Strait area and the Three King Islands, from 75 to 205 m depth.

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.

DI MARTINO E. et al., New cheilostome bryozoan Powellitheca
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. 3A).Primary orifice of fertile zooids larger than that of autozooids, rounded quadrangular, slightly broader than long (Fig. 3E-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. 3D).

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.(Waters, 1887)   Other material NEW ZEALAND: NIWA 98228, 15 colonies from Hatuma Quarry, Waipukurau.

DI MARTINO E. et al., New cheilostome bryozoan Powellitheca
angled at 90˚ to 180˚ to encircle the ancestrula (Fig. 6D).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, 6A-B).Frontal shield lepralioid, slightly convex, granular, regularly and evenly perforated by 40-50 small, circular pores about 10-15 μm in diameter (Fig. 6A-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. 6F); 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 5C-D, 6F).Lyrula and oral spines absent (Fig. 6G).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 5A-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 5A-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 5C, 6C, F), no crossbar.Kenozooids budded at junctions between colonies growing on same substratum, similar to autozooids   European Journal of Taxonomy 207: 1-17 (2016) in size and in the appearance of the frontal shield but lacking apertures (Fig. 6B).Oval, multiporous (at least six pores) septula visible on vertical walls (Fig. 6H), about 40 μm long by 20 μm wide.Intramural, reparative budding also observed (Fig. 6C).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 19 th 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.

Discussion
The continental shelf around New Zealand supports a rich bryozoan fauna estimated to number almost 1000 species (Gordon et al. 2009).Evidence from the fossil record suggests that high diversities of bryozoans have characterized this region for at least 50 million years (e.g., Gordon & Taylor 2015).
Current research focusing on Plio-Pleistocene bryozoans from the Wanganui Basin has prompted the re-evaluation of a common cheilostome usually known as Emballotheca waipukurensis (Waters, 1887), which was originally described from Waipukurau Gorge in Hawkes Bay.Comparison of this species with the Australian type species of Emballotheca, E. quadrata (MacGillivray, 1880), reveals major differences in skeletal morphology.In particular, the autozooidal orifice in E. quadrata is cormidial, while the ooecium is of the lepralielliform type, with an uncalcified endooecium and a calcified ectooecium, covered by the sutured secondary calcification formed by several zooids distal and distolateral of the fertile zooid.These features contrast with the non-cormidial autozooidal orifice and the microporelliform ooecial structure of the New Zealand species.

Table 1 .
Measurements in microns of Powellitheca terranovae gen.et sp.nov.DI MARTINO E. et al., New cheilostome bryozoan Powellithecagen.et sp.nov.differ from true P. waipukurensis comb.nov. in having an anvil-shaped median lyrula that is difficult to observe in frontal view because it is directed either vertically downwards or only slightly distally angled.Further differences are the lack of a suboral umbo in the non-ovicellate zooids of P. terranovae gen.et sp.nov., a feature that in this species is restricted to the female zooids, and the different shape of the avicularium rostrum, which is spatulate in P. waipukurensis comb.nov.but distally tapered and rounded in P. terranovae gen.et sp.nov.They also differ in the size of the zooids, orifice and ooecia, which are slightly larger in P. terranovae gen.et sp.nov.
(Rust & Gordon 2011)terial from New Zealand previously identified as Emballotheca waipukurensis shows that it too differs from the Australian type species of Emballotheca and, although close to the fossils from New Zealand, differs in several respects, warranting its recognition as a new species.Accordingly, a new genus, Powellitheca gen.nov., is proposed for the fossil and Recent New Zealand species previously assigned to Emballotheca.Because of the future possibility of obtaining molecular sequence data from Recent Powellitheca gen.nov.andthereforeplacing it in a broader phylogenetic context, P. terranovae gen.et sp.nov. is chosen as the type species of this new genus in preference to the fossil species P. waipukurensis comb.nov.Another, rarer Recent species of Powellitheca gen.nov. is also recognized, P. labiosa gen.et sp.nov.The known distribution of Powellitheca gen.nov. is limited to the North Island of New Zealand and includes one fossil and two living species.The geologically oldest occurrence is of P. waipukurensis DI MARTINO E. et al., New cheilostome bryozoan Powellitheca comb.nov., which dates back to the Pliocene of Hawkes Bay.This species is common in the Wanganui Basin until the early Pleistocene, and is a component of a rich and abundant encrusting bryozoan fauna associated with Ostrea association and Paphies association palaeocommunity shellbeds(Rust & Gordon 2011).These shellbeds are interpreted as deposited mainly in shoreface and inner shelf environments.In contrast, the two Recent species P. terranovae gen.et sp.nov.and P. labiosa gen.et sp.nov.are found in deeper water, from 75 to 205 m.The first of these species has a broad distribution, from Cook Strait to the Three King Islands at the northern tip of New Zealand, while the second species is currently known only from Three King Islands.