New records of Pennatulacea ( Anthozoa : Octocorallia ) from the African Atlantic coast , with description of a new species and a zoogeographic analysis *

Marine benthic fauna from the area between 20 and 30°S off Namibia is one of the poorly studied in the world oceans. Unlike many other regions, it was not visited by the early oceanographic expeditions, except for a few samples collected offshore by the Deutsche Tiefsee Expedition (Zibrowius and Gili, 1990). the study of the area underwent considerable expansion in the 1970s and 1980s, when the area was one of the world’s most important fisheries regions (Shannon, 1985). Studies that monitored the fisheries in the region commenced in 1979, under the project entitled “Estudio de las Pesquerías del África Austral (EPAU)” [Southern African Fisheries Studies] funded by the Spanish Fisheries Administration. For over 10 years fisheries surveys were carried out using midwater trawls, purse seines, and other pelagic sampling gear. However, given the interest in the area and the dearth of information on biodiversity in the area, the Programme Director, Dr. E. Macpherson [Instituto de Ciencias del Mar (ICM), Barcelona] arranged for a series of bottom trawls to be carried out on each survey. These trawls yielded one of the best biological collections in existence for the Namibian region. Following the termination of this programme, the fisheries studies were continued, but other biological studies almost ceased. Therefore, the ICM’s biological collections from the SCI. MAR., 65 (1): 59-74 SCIENTIA MARINA 2001


INTRODUCTION
Marine benthic fauna from the area between 20 and 30°S off Namibia is one of the poorly studied in the world oceans.Unlike many other regions, it was not visited by the early oceanographic expeditions, except for a few samples collected offshore by the Deutsche Tiefsee Expedition (Zibrowius and Gili, 1990).the study of the area underwent considerable expansion in the 1970s and 1980s, when the area was one of the world's most important fisheries regions (Shannon, 1985).
Studies that monitored the fisheries in the region commenced in 1979, under the project entitled "Estudio de las Pesquerías del África Austral (EPAU)" [Southern African Fisheries Studies] funded by the Spanish Fisheries Administration.For over 10 years fisheries surveys were carried out using midwater trawls, purse seines, and other pelagic sampling gear.However, given the interest in the area and the dearth of information on biodiversity in the area, the Programme Director, Dr. E. Macpherson [Instituto de Ciencias del Mar (ICM), Barcelona] arranged for a series of bottom trawls to be carried out on each survey.These trawls yielded one of the best biological collections in existence for the Namibian region.Following the termination of this programme, the fisheries studies were continued, but other biological studies almost ceased.Therefore, the ICM's biological collections from the area afford a unique opportunity to examine biodiversity in this region of biogeographic interest.
In addition to the upwelling that occurs, the southward flowing Angola Current and the northward flowing Benguela Current converge in the Namibian region.
The studies carried out to date in the framework of the EPAU programme have made significant contributions to existing knowledge of benthic fauna (see Macpherson, 1984;Uriz, 1988, Gili et al., 1989) and plankton (see Olivar and Fortuño, 1985;Pagès et al., 1992).These studies have revealed the special characteristics of the Namibia region together with its biological richness and high level of biodiversity.
The present study reports on the pennatulacean fauna (Cnidaria, Anthozoa) collected in the EPAU programme in the region off Namibia and Guinea Bissau.Pennatulaceans are one of the most common zoological groups in moderately deep and deep waters in all oceans but are still not sufficiently well known from a geographical point of view (Williams, 1995).

MATERIAL AND METHODS
The pennatulacean material studied in the present report is from nine cruises off the west coast of Africa, one of them in the Guinean Gulf, and the remainder in the Southeast Atlantic.The equipment used was a large commercial fisheries trawl.More than 350 specimens of 13 species (one of them here considered at the generic level only) were collected from 54 stations.These are as follows: -14 stations off Guinea Bissau coast, near Bissagos Islands, 25-256 m deep (cruise GUINEA BIS-SAU, December 1984-February 1985).
-1 station on the Walvis Ridge (on Valdivia Bank, the shallowest part of the ridge), 1112 m deep (cruise BENGUELA VI, 1984).
The specimens collected from these cruises are deposited in the California Academy of Sciences (CASIZ), South African Museum (SAM) Cape Town, Instituto de Ciencias del Mar (ICM) of Barcelona, and Laboratorio de Biología Marina (LBM) of the University of Sevilla, Spain.Diagnostic descriptions included in this paper are from these specimens.
Some pennatulacean specimens from adjacent areas have been used for comparisons.These speci-PENNATULACEA FROM THE AFRICAN ATLANTIC COAST 61 All material was preserved in 70% ethanol.Sclerites from different parts of the colonies were prepared for study by scanning electron microscope, and permanent mounts were made for observation by light microscope.
The list of stations including the different location features and the species collected is indicated in Table 1.
Diagnosis: Colonies elongated and cylindrical, preserved specimens up to 250 mm in length.Rachis 73% of colony length, peduncle 27% of colony length.Autozooids relatively large and distributed on the rachis in all directions.Siphonozooids in longitudinal rows on the rachis.Axis short.Sclerites of the rachis platelet, 0.08 mm in length.Sclerites of the peduncle similar to the rachis, 0.09 mm in length.
Remarks: All specimens examined are from off the coast of Guinea.However, this species has been reported from the Atlantic south of the Bay of Biscay, the Mediterranean, the south-west African coast (Kükenthal, 1915;Molander, 1929;Broch, 1958), and even a single locality reported from southern Mozambique, Indian Ocean (Tixier-Durivault, 1960).Williams (1990) reported the bathymetric distribution of this species to be between 13 and 91 m.The colonies studied here were from 25 to 188 m.
Remarks: This species has been recently described as part of a revision of some Cavernularia species from the eastern Atlantic and western Pacific Oceans (López-González et al., 2000).In that paper, additional material belonging to this species and previously deposited at the MNHN and ZMH was also re-examined.All known colonies of C. kuekenthali are from the Gulf of Guinea, from 5 to 32 m in depth.For additional details about the external and internal anatomy of this species see López-González et al. (2000).
Remarks: This pennatulacean is the type species of the recently described genus Amphibelemnon (López-González et al., 2000).These authors also re-examined additional material previously deposited at the SAM.This species is known only from off the Namibian coast, between 91 and 304 m depth.For additional details about the external and internal anatomy of this species see López-González et al. (2000).
Diagnosis: Colonies elongate, cylindrical and clavate, gradually widening distally, up to 290 mm in length.Rachis 64% of colony length, peduncle 36% of colony length.The whole colony is very rigid because of the high density of sclerites.Autozooids relatively large and distributed on the rachis in two longitudinal rows.Siphonozooids with two-toothed calyces Axis thin.Sclerites of the rachis three-flanged spindles with tuberculate ends, 0.21-0.57mm in length.Sclerites of the peduncle rods of similar shape to those of the rachis, 0.10-0.21mm in length.
Remarks: Nine species of Kophobelemnon have been considered valid in the last synopses of the living genera of Pennatulacea (Williams, 1995).Four Kophobelemnom species are exclusive to Indo-Pacific areas, two are from Atlantic plus Pacific localities, one from the Caribbean, one from the Mediterranean, and the ninth from the Antarctic Peninsula (Kükenthal, 1915;Keller, et al., 1975;Parternak, 1975;Williams, 1990).The known bathymetric range of the genus is very wide, between 36-4400 m.
Diagnosis: Colonies elongate, whip-like, up to 220 mm in length.Rachis 73% of colony length, peduncle 27% of colony length.Autozooids mainly arranged in oblique rows of 4-5 polyps, in two longitudinal rows on the rachis, fused at bases, and relatively large.Siphonozooids minute and numerous.Sclerites absent, except for minute ovals in the inner region of peduncle.
Remarks: Anthoptilum grandiflorum has been recorded from several western, eastern and southern Atlantic localities, between 238-2500 m in depth, and was recently considered cosmopolitan (Williams, 1990(Williams, , 1995)).
Diagnosis: Colonies elongate, whip-like, up to 160 mm in length.Rachis 69% of colony length, peduncle 31% of colony length.Autozooids arranged in two longitudinal series, facing upward, adaxial side of calyces appressed to lateral margin of the rachis.Siphonozooids contained on the rachis, two per autozooid.Sclerites of the rachis are threeflanged spindles, 0.38-0.90µm in length.Sclerites of the peduncle are three-flanged rods.Preserved colonies have orange calyces and whitish coenenchyme.
Remarks: The single variable valid species of this genus has a cosmopolitan distribution, with a wide bathymetric range of 793-4300 m (Kükenthal, 1915;Williams, 1990Williams, , 1995)).This record confirms the presence of D. gracile in southern African Atlantic waters, reported by Williams (1990).

Diagnosis:
The single fragment studied is 130 mm in length.Rachis slender, peduncle missing.Autozooids fused at the base forming short polyp leaves.These are more-or-less paired, each with 6-8 polyps retractile into fleshy calyces with smooth distal border.Siphonozooids difficult to observe, contained on the rachis.Sclerites absent.The fragment of the rachis is cream in colour.
Diagnosis: Colonies elongate, preserved specimens up to 180 mm in length.Rachis slender, 64% of colony length, peduncle 36% of colony length.Autozooids fused at the base forming short polyp leaves.These are positioned alternately, with 5-6 polyps per polyp leaf.Autozooids retractile into fleshy calyces with slightly tuberculate distal border.Siphonozooids difficult to observe, contained on the rachis.Sclerites absent.The colonies are brownish in colour.
Remarks: This species is easily distinguished from the other Virgularia species by having a small number of autozooids per polyp leaf (3-6) and small tubercles on the distal borders of the fleshy calyces.Virgularia tuberculata is a well known pennatulacean species from North Atlantic and Arctic waters (see Kükenthal, 1915).However, there are some reports (Tixier-Durivault, 1961, 1963)  External morphology: Colonies examined up to 115 mm long, very slender, but moderately rigid and straight, brittle.The rachis is 72-42 mm long (63% of the colony length) and 2.5 mm in maximum width, while the peduncle is 43 mm in length (37% of colony length) and 3 mm in width (the peduncle was broken in the paratype).The rachis with polyp leaves projecting upward, adnate, up to 6 pairs in 2 cm of rachis.Pairs of polyp leaves small and not crowded distally, and more crowded on the lower part of the rachis.Polyp leaves placed alternately in the lower part of the rachis, and more-orless oppositely in the upper part.The large needles of the supporting armature slightly reaching the fused basal part of the autozooids, but never covering the free bodies.Three autozooids per leaf, increasing slightly in size from the inner to the outer polyps.Autozooid bodies are cylindrical, not fused laterally.The tentacles with one row of 12-14 pinnules on each side.Lateral body walls of the autozooids and aboral side of tentacles with visible sclerites.Peduncle elongate with a moderate bulb on the distal mid-portion.Colour: Preserved specimens are white to grey in colour.

Distribution:
The species is currently known only from off the Namibian coast, between 245 and 318 m depth.

Etymology:
The specific epithet is dedicated to Dr. Enrique Macpherson, head of the Spanish Programme "The study of Austral African Fisheries" for making available the octocoral collections from Benguela cruises in South Africa and Namibia, where the new species of Stylatula was found, and specially for his relevant contribution to the knowledge of Namibian marine biodiversity.
Stylatula diadema is clearly distinguished from the other Stylatula species listed above because it has siphonozooids placed in rosettes on the lower ventral surface of the polyp leaves, while in the other species the siphonozooids are placed on the rachis, in the polyp leaf axils (Bayer, 1961).
Within the remaining nine Stylatula species, only S. elegans, S. brasiliensis, and S. macphersoni sp.nov.have less than 15 autozooids per polyp leaf (Kükenthal, 1915;Bayer, 1961).However, S. brasiliensis is easily distinguished from the other two species by the fact that the autozooids of each polyp leaf are fused together, except for a short distal calycular part, while in S. elegans and S. macphersoni sp.nov., the body walls of autozooids are distinctly separate, and joined only in their lowest parts (Kükenthal, 1915; present account) (Figs.1C-D, and 2A-B).

Remarks:
The present report confirms the presence of this species off the Namibian and South African coasts, reported by Williams (1990).The PENNATULACEA FROM THE AFRICAN ATLANTIC COAST 69 species is present in the southeastern Atlantic, from the Senegal-Guinea coast to South Africa.The systematic position of this species was discussed by Williams (1990).
Diagnosis: Colonies bilateral, up to 118 mm in length, with 29-33 polyp leaves on the rachis.Rachis is 63% of the colony length, and has a narrow naked dorsal tract, up to 78 mm long.Peduncle 37% of the colony length, with a distinct medial bulb.Autozooids 39-45 per polyp leaf placed in 1-2 rows.Autozooid calyces with 4-8 marginal teeth.Mesozooids on the dorsal region of the rachis and on the basal dorsal region of the polyp leaves (only one or two mesozooids).Siphonozooids on the rachis dorsally, and between the polyp leaves ventrally.Sclerites are usually three-flanged spindles, minute ovals in the interior of peduncle.

Pennatula inflata
Diagnosis: Colonies bilateral, up to 275 mm in length, with 29-31 polyp leaves on the rachis.Rachis is 70% of the colony length.Rachis with wide naked dorsal tract up to 13 mm long.Peduncle 30% of the colony length, with a distinct medial bulb.Autozooids 50-54 per polyp leaf placed in 1-2 rows.Autozooid calyces with 8 marginal teeth.
Mesozooids on the basal dorsal margin of the polyp leaves and on two narrow longitudinal bands along the dorsal rachis.Siphonozooids on the rachis, between the polyp leaves.Sclerites are usually three-flanged spindles, minute ovals in the interior of the peduncle.
Remarks: This species, originally described from off Somalia, was reported for the first time from the west South African coast by Tixier-Durivault (1954, as Pennatula phosphorea), and recently reported from the south Namibian coast by Williams (1990).These three specimens were the first records of P. inflata in the Atlantic Ocean (Tixier-Durivault, 1954) and two additional ones were collected in Lambert's Bay (32º6'S 18º18'E) (Williams, 1990).The present account, based on a larger number of colonies, 35 in total, confirms the distribution of this species along the west African coast, and extends its known range north to off Walvis Bay (23º8'S-13º5.6'E).
Remarks: Three colonies belonging unquestionably to the genus Pteroeides were collected from the Guinea-Bissau cruise.However, according to Williams (1990:107) this genus is in need of revision.The study of the type material of the over 87 species reported in the literature (if they are still available) is necessary to recognise an unknown number of valid species (at least 25 after Williams, 1995).We prefer to identify this material only at a generic level, as more information about the species of this genus from the African Atlantic coast is needed.ZOOGEOGRAPHY Williams (1992) provided a biogeographical analysis of the southern African octocoral fauna, including the Pennatulacea.The distribution of this fauna extends along part of the Atlantic coast of Africa (Williams, 1992: Figs.1, 2, 5).Williams (1999) listed literature citations relevant to the biogeography of the Pennatulacea, as well as taxa inhabiting the eastern Atlantic.
The West African coast is defined here as the region between Tangier (Morocco) in the north and Cape Point (Cape of Good Hope, South Africa) in the south (Fig. 6), and is synonymous with the African Atlantic coast.
The West African pennatulacean fauna can be divided into three geographic regions largely associated with the prevailing coastal currents (Fig. 6).The cold water Canary Branch of the North-Eastern Atlantic Current flows southward along the coasts of the Iberian Peninsula and the western bulge of Africa as far south as Liberia.The warmer nearequatorial Guinea Current flows eastward from Liberia to Gabon, while the cold water Benguela Current sweeps northward from Cape Point to Angola.
Zoogeographic regions, defined here for the purposes of the present study are as follows: Northern Atlantic -widespread in the Arctic and/or North Atlantic; found in the Atlantic outside of the Canary region.
Canary -including the southern Bay of Biscay, Iberian Peninsula, western Mediterranean Sea, western Canary Islands, and along the northwest African coast to Liberia.
Gulf of Guinea -along the African coast between Liberia in the west and Gabon in the east.
Benguela -along the southwest African coast from Angola in the north to Cape Point in the south.
Cape Endemic -the coastal region of the Cape Province and Natal, South Africa (delimited by Williams, 1992: 361).
Widespread -scattered distribution; taxa found in various parts of the world's seas; widespread to nearly cosmopolitan.

Analysis
The data in Table 2, show that the shallow water biogeographic affinities of western Africa can be divided into three components: (1) West African [Canary 22.22% + Gulf of Guinea 14.81 % + Benguela 18.52%], representing 55.5% of the fauna; (2) North Atlantic [representing more widespread Atlantic taxa, 3.7% of the fauna]; (3) Cape Endemic [representing the southern African region, 7.4% of the fauna].
The North Atlantic and Canary regions can be viewed as cold water boreal, the Gulf of Guinea region as tropical, the Benguela region as cold water austral, and the Cape Endemic as primarily warm water temperate.
These shallow water taxa account for 66.6% of the fauna.The remainder (33.3%) is comprised of widespread faunal taxa elements.These are species with ranges that extend outside of the Atlantic PENNATULACEA FROM THE AFRICAN ATLANTIC COAST 71 Ocean, ranging from those with relatively limited distributions to nearly cosmopolitan ones.These widespread taxa are species that have deep water bathymetric distributions (Fig. 7).In the Octocorallia, taxa with limited geographic ranges (endemics) tend to inhabit shallow waters of coastal regions, while many of those with widespread to cosmopolitan distributions inhabit deeper waters of the continental slope to abyssal plains (Williams,1992).

records of Pennatulacea (Anthozoa: Octocorallia) from the African Atlantic coast, with description of a new species and a zoogeographic analysis*
2001New

TABLE 1 .
(Cont.)-The station code, date, coordinates, depth, geographical area, and the species collected for each cruise.
FIG. 6. -Map of Africa showing various regions of western Africa.