Some deep-water cheilostome Bryozoa from the south coast of South Africa

· · · · · · · · · · · · · · · · · · · · · 5 Introduction · · · · · · · · · · · · · · · · · · · 5 Materials and methods· · · · · · · · · · 5 Systematics · · · · · · · · · · · · · · · · · · · 5 Order Cheilostomata · · · · · · · · · · · 5 Suborder Neocheilostomina · · · · · 5 Family Calloporidae · · · · · · · · · · · · 5 Genus Amphiblestrum · · · · · · · · · · · 5 Family Candidae · · · · · · · · · · · · · · · 6 Genus Menipea · · · · · · · · · · · · · · · · 6 Family Aspidostomatidae· · · · · · · · 6 Genus Aspidostoma · · · · · · · · · · · · · 6 Family Adeonellidae · · · · · · · · · · · · 6 Genus Adeonella · · · · · · · · · · · · · · · 6 Family Romancheinidae· · · · · · · · · 8 Genus Escharoides· · · · · · · · · · · · · · 8 Family Microporellidae · · · · · · · · · · 8 Genus Flustramorpha · · · · · · · · · · · · 8 Family Petraliellidae · · · · · · · · · · · · 8 Genus Mucropetraliella · · · · · · · · · · · 8 Family Lacernidae· · · · · · · · · · · · · · 8 Genus Arthopoma· · · · · · · · · · · · · · · 8 Family Phidoloporidae · · · · · · · · · · 9 Genus Schizoretepora · · · · · · · · · · · 9 Genus Reteporella · · · · · · · · · · · · · 10 Acknowledgements · · · · · · · · · · · 10 References· · · · · · · · · · · · · · · · · · · 10 African Natural History 12: 5–11 — ISSN 2305-7963 [Afr. nat. history] Online only DOI: http://dx.doi.org/10.17159/2305-7963/2016/v12n1a2 — ZooBank: urn:lsid:zoobank.org:pub:AE33E453-01D8-46CF-BC41-7E6EE57BD1BB (http://www.zoobank.org) Published on the 6th of June 2016 at Sabinet, Pretoria (http://reference.sabinet.co.za/sa_epublication/afnathist) Amphiblestrum inermis Hayward & Cook, 1983: 12, fig. 1D–F. not Membranipora inermis Kluge, 1914: 663, pl. 34 fig. 6. Material examined Current material: SAMC-A28657, station ANO183 (33°56’S, 18°22’E), depth 95 m, collected by G. Harkins, 30 May 2000. Other material: SAMC-A28569, Bakoven (33°56’S, 18°22’E), depth 8 m, collected by W. Florence, 5 May 1999. Remarks The confused synonomy of Amphiblestrum triangularis (O’Donoghue, 1924) with A. inermis (Kluge, 1914) was resolved by Florence et al. (2007). The current specimens agree closely with a specimen from Bakoven (SAMC-A28569) described by Florence et al. (2007). Family CANDIDAE d’Orbigny, 1851 Genus Menipea Lamouroux, 1812 Menipea ornata (Busk, 1852) Cellularia ornata Busk, 1852: 20 pl. 20, figs 3–4. Menipea ornata: Harmer, 1923: 34; Hayward & Cook 1983: 39; Florence et al. 2007: 21, figs 7 F–I. Menipea flabellum Marcus, 1922: 13, fig. 7. Cellularia infantae O’Donoghue, 1924: 30, pl. 1 (fig. 6); O’Donoghue & de Watteville 1935: 30; O’Donoghue & de Watteville 1937:12. Material examined Current material: SAMC-A28658, station ANO183 (33°56’S, 18°22’E), depth 95 m, collected by G. Harkins, 30 May 2000. Other material: SAMC-A28588, Justin’s Caves, Oudekraal (33°58’90”S, 18°20’65”E), depth 15 m, collected by W. Florence, 24 April 1999. SAMC-A28589, Homestead Plateau, Oudekraal (33°58’90”S, 18°21’30”E), depth 10 m, collected by W. Florence, 30 April 1999. Remarks The confused synonomy associated with this species has been cleared up by Hastings (1943: 332). The current specimens agree closely with specimens from Oudekraal (SAMC-A28588, SAMC-A28589) described by Florence et al. (2007). Menipea marionensis Busk, 1884 Menipea marionensis Busk, 1884: 21, pl. 4, figs 3, 3a; Harmer 1923: 341, pl. 17, fig. 22; pl. 19 figs 43–45. Hayward & Cook 1983: 40. Florence et al. 2007: 23, figs 8E–I. Material examined Current material: SAMC-A28659, station ANO183 (33°56’S, 18°22’E), depth 95 m, collected by G. Harkins, 30 May 2000. Other material: SAMC-A28655, Castle Rock, False Bay (34°14’S, 18°29’E), depth 15 m, collected by G. Isaacs, 2 March 2000. Remarks This species is very similar to Menipea triseriata but differs from it by having a more prominent gymnocyst, one distolateral spine per outer zooid and nine zooids per internode as opposed to 15. The current specimens agree closely with a specimen from False Bay (SAMC-A28655) described by Florence et al. (2007). Family ASPIDOSTOMATIDAE Jullien, 1888 Genus Aspidostoma Hincks, 1881 Aspidostoma livida (Hayward & Cook, 1983) Fig. 1A–C Aspidostoma livida Hayward & Cook, 1983: 36, fig. 10. Material examined Current material: SAMC-A28660, station ANO183 (33°56’S, 18°22’E), depth 95 m, collected by G. Harkins, 30 May 2000. Description Colony erect, bilaminar and reticulate, forming broad plates. Deep blue-grey in colour when alive and when dried. Fenestrulae long and oval occurring frequently throughout the colony. Autozooids large and hexagonal, convex, frontal surface granular and separated by distinct grooves. Frontal wall convex but becoming concave towards the opesia; proximal edge of opesia with thick ‘axehead-shaped’ lip with thick median edge extending proximally from it. Distal end of zooid raised as a prominent hood. Ovicell globose, flattened frontally and coarsely granular; opening via a hooded aperture located distal to the zooid operculum. Vicarous avicularia sparsely scattered over the colony; rostrum acute triangular and directed distolaterally. No spines were observed. Substratum, depth range and ecology May be found encrusting rocks and stones in sublittoral waters. The older or worn parts of the colony usually colonized by other bryozoans and entoprocts. Depth range: 95–700 m. Geographic distribution This species has been reported only from South Africa and is distributed from deeper waters of Mossel Bay to the Wild Coast along the South African coastline. Remarks This species is easily identified and is unique from other congeneric species in that the only other erect species of Aspidostoma develop cylindrical colonies as opposed to the reticulate anastomosing form of the current specimen. The specimen is consistent with the description and figured specimen of Hayward & Cook (1983). Family ADEONELLIDAE Gregory, 1893 Genus Adeonella Busk, 1884 Adeonella pluscula Hayward, 1988 Adeonella pluscula Hayward, 1988: 181, fig. 28A–D; Florence et al. 2007: 12, fig. 4A–B. Material examined Current material: SAMC-A28661, station ANO183 6 African Natural History, Volume 12, 2016 Florence: Deep-water cheilostome Bryozoa from the south coast of South Africa 7 Fig. 1. A–C, Aspidostoma livida (Hayward & Cook, 1983). D–F, Flustramorpha marginata (Krauss, 1837). G–I, Arthopoma lioneli sp. nov.


INTRODUCTION
Previous studies on the deep-water (80-1300 m) bryozoan fauna by Hayward & Cook (1979, 1983) have revealed a remarkable diversity of no fewer than 159 species reported from the collections of the South African Museum's Meiring Naudé cruises of the late 1970s.The very low-effort collection reported on here revealed 12 species, one of which, Arthropoma lioneli sp.nov., is new to science.These findings reaffirm the need for targeted deep-water sampling of benthic bryozoans in order to reveal the potential regional diversity of this phylum.The focus of future surveys should be directed at the south and west coasts of South Africa where there is a paucity of knowledge of bryozoans.Following the remarkable discoveries made by Hayward & Cook (1979, 1983) future targeted work in this region is expected to yield significantly new knowledge of the deep-water fauna.

MATERIALS AND METHODS
General methods closely follow those of Florence et al. (2007).Byozoan specimens were collected from by-catch of one bottom-trawled station (ANO183 -35°40'S, 22°53'E, depth 95 m) along the south coast of South Africa during a survey of the Dr Fritjov Nansen (a demersal trawler) during May 2000.Only species that were not described in Florence et al. (2007) are here fully described and figured from the current material as all others agreed closely with the descriptions of conspecific species provided by those authors.All material has been deposited in the collections of the Natural History Collections Department, Iziko Museums of South Africa, Cape Town.Catalogue numbers are provided in the 'material examined' sections below.The following abbreviations are used for the tabulated measurements of Arthropoma lioneli sp.nov.: autozooid length (Lz), autozooid width (lz), orifice length (Lso), orifice width (lso), ovicell length (Lov) and ovicell width (lov).

Remarks
This species is very similar to Menipea triseriata but differs from it by having a more prominent gymnocyst, one distolateral spine per outer zooid and nine zooids per internode as opposed to 15.The current specimens agree closely with a specimen from False Bay (SAMC-A28655) described by Florence et al. (2007).

Description
Colony erect, bilaminar and reticulate, forming broad plates.Deep blue-grey in colour when alive and when dried.Fenestrulae long and oval occurring frequently throughout the colony.Autozooids large and hexagonal, convex, frontal surface granular and separated by distinct grooves.Frontal wall convex but becoming concave towards the opesia; proximal edge of opesia with thick 'axehead-shaped' lip with thick median edge extending proximally from it.Distal end of zooid raised as a prominent hood.Ovicell globose, flattened frontally and coarsely granular; opening via a hooded aperture located distal to the zooid operculum.Vicarous avicularia sparsely scattered over the colony; rostrum acute triangular and directed distolaterally.No spines were observed.

Substratum, depth range and ecology
May be found encrusting rocks and stones in sublittoral waters.The older or worn parts of the colony usually colonized by other bryozoans and entoprocts.Depth range: 95-700 m.

Geographic distribution
This species has been reported only from South Africa and is distributed from deeper waters of Mossel Bay to the Wild Coast along the South African coastline.

Remarks
This species is easily identified and is unique from other congeneric species in that the only other erect species of Aspidostoma develop cylindrical colonies as opposed to the reticulate anastomosing form of the current specimen.The specimen is consistent with the description and figured specimen of Hayward & Cook (1983).

Remarks
Adeonella pluscula was first described by Hayward (1988).He noted that the branches of this colony are very broad at the growing margins and consist only of autozooids and gonozooids whereas the lateral edges of the branches consist only of avicularia and kenozooids.The current specimens agree closely with descriptions in Hayward (1988) and specimens from False Bay (SAMC-A28609) and Oudekraal (SAMC-A28610) described by Florence et al. (2007).

Remarks
Although the current specimen is very worn and collected from the seabed in the region of fragments of other dead colonies it is easily recognizable as Escharoides contorta.This species is most similar to E. distincta (Hayward & Cook, 1979) but differs from it in the orientation of the oral spines and the morphology of the proximal-median lip.The current specimen agrees closely with a specimen from Oudekraal (SAMC-A28618) described by Florence et al. (2007).

Description
Colony erect, bilaminar and foliaceous.Light brown when alive and dark yellow when dry. Autozooids are hexagonal, broad and flat, arranged multiserially alternating; sepa-rated by distinct raised sutures.Primary orifice semicircular with distinct lateral condyles.Frontal shield granular with numerous small pores and a medially positioned, crescentic ascopore.Avicularium adventitious and positioned proximolaterally to the orifice; rostrum oval with a long setiform mandible.Ovicell prominent.

Substratum, depth range and ecology
Lives erect on hard substrata.Depth range: 80-450 m.

Geographic distribution
This species has been reported only from South Africa and is distributed from offshore of Mossel Bay to Sodwana Bay.

Remarks
Hayward & Cook (1983) pointed out the difficulties in distinguishing between Flustramorpha species.F. marginalis is most similar to F. flabellaris (Busk, 1854) and F. angusta (Hayward & Cook, 1979).F. marginalis has avicularia with long setiform mandibles and a palate that is orientated at anoblique, or perpendicular, angle to the frontal plane as opposed to short acuminate mandibles and a parallel palate in F. flabellaris.F. angusta has a proportionally small, narrower and depressed ovicell, which is progressively obscured by secondary calcification, and a semi-elliptical orifice with a straight proximal border that distinguishes it from F. marginalis.

Remarks
This species was first described by Hayward & Cook (1983), who discussed its similarities to M. watersi (Harmer, 1957).The current specimen agrees closely with Hayward & Cook's (1983) description as well as the type specimen and is easily recognizable.This record represents the most western occurrence of M. asymmetrica at rather a shallow depth, suggesting that this species has a wider bathymetric and geographic range than previously thought.

Description
Colony encrusting unilaminar; forming irregular patches.White when alive and when dry. Autozooids hexagonal and convex; separated by distinct grooves (ca.1.01 × 0.93 mm).Frontal shield smooth, perforated by numerous small kidney-shaped pores, becoming less distinct in later ontogeny; indistinct imperforate ridge below the primary orifice but not sufficiently developed to be considered an umbo.Primary orifice with D-shaped poster, slightly wider than long (ca.0.16 × 0.18 mm excluding sinus), proximal border straight and indented medially by a deep, narrow, sinus that is approximately longer than half the length of the poster; condyles thick, smooth, rounded towards each other thereby narrowing the entrance of the sinus.Three to six distal oral spines present.Ovicell prominent, globular and wider than long; frontal surface slightly granular and one distinct spine base on either side, distolateral, of the primary orifice.No avicularia observed.

Geographic distribution
This species is known only from South Africa and has a south-coast distribution range from False Bay to Port Alfred.

Remarks
Arthropoma is a small genus of lacernid Bryozoa that previously comprised just two valid recent species; A. cecilii (Audouin, 1826) and A. inarmata Gontar, 1993.The latter has been reported only from the Kuril Islands in Russia (Gontar, 1993).While A. cecilii has a known warmtemperate to circumtropical distribution; it has also previously been reported from South Africa by Hayward & Cook (1983).In addition, these authors also reported on two other species from South Africa; A. circinatum (MacGillivray, 1869) and an unnamed species, Arthropoma sp.During the current study a re-examination of Hayward and Cook's specimens supports the synonomic treatment of A. circinatum (BMNH 1983.11.5.49) with Phonicosia circinata (MacGillivray, 1869), in accordance with Gordon (1984).Examination of the fragmentary specimens of Arthropoma sp.Hayward & Cook 1983 (SAMC-A26845, SAMC-A26763), reveals that it is consistent in all discernible characters with the current specimens and is herein synonomized with A. lioneli sp.nov.
The narrow slit-like oral sinus, small kidney shaped frontal pores and the presence of oral spines primarily distinguishes Arthropoma lioneli sp.nov.from all other Arthopoma species; A. cecilii and A. inarmata posses a wide or U-shaped oral sinus and round frontal pores, and lack oral spines.A. lioneli sp.nov.has larger, more hexagonal, autozooids than both A. cecilii (0.7-0.8 × 0.4-0.6 mm) and A. inarmata (0.8-0.1 × 0.52-0.60mm).In addition, A. lioneli also differs from A. cecilii as its condyles are rounded towards each other rather than being flat and its ovicell frontal wall is not tessellate but rather only finely granular.The above-mentioned differences are herein considered sufficient to warrant the erection of A. lioneli sp.nov.

Remarks
This species is extraordinary in terms of its variable colony morphology.It is either unilaminar and fenestrate or bilaminar and sheet-like, or both in the same colony, with fenestrulae present at the growing edge.Hayward & Cook  1983) noted that there is variability in the width of the primary orifice in various specimens from Australia and South Africa.This was also noted in the current specimens.Furthermore the Australian specimens developed long (0.8 mm) antenniform spines, whereas the present specimens from South Africa appear to have consistently shorter spines (mean = 0.5 mm, n = 20).The avicularia and ovicells appear to be consistent with the specimens of Hayward & Cook (1983) and therefore also with the Australian specimens.

Remarks
Hayward & Cook (1983) defined the most characteristic feature of Reteporella lata to be the pear-shaped ovicell with its long labellum.These authors suggest that Busk (1884) missed this in his illustration of the type specimen of R. lata, but upon re-examination they found that the type was consistent with their Meiring Naudé specimens.The present specimens in this study are consistent with those of the above-mentioned works.