Twenty Marine Benthic Algae New to South Africa, with Emphasis on the Flora of Kwazulu-Natal
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Botanica Marina Vol. 45,2002, pp. 413-431 © 2002 by Walter de Gruyter • Berlin • New York Twenty Marine Benthic Algae New to South Africa, with Emphasis on the Flora of Kwazulu-Natal O. D e Clerci©'*, H. R. Engledow3, J. J. Boltonb, R. J. Anderson0 and E. Coppejans" a Research Group Phycology, Biology Department, Ghent University, Krijgslaan 281 / S8,9000 Ghent, Belgium b Botany Department, University of Cape Town, Private Bag, 7700 Rondebosch, South Africa c Marine and Coastal Management, Seaweed Unit, Private Bag X2,8012 Roggebaai, Cape Town, South Africa * Corresponding author: [email protected] A total of 20 new records of benthic marine algae has been added to the flora of South Africa, consisting of 6 taxa of Phaeophyta and 14 Rhodophyta. Most species have a pantropical or Indo-Pacific distribution and are generally known from several localities in the Indian Ocean (e.g .Asteronema breviarticulatum, Ceramium cingulatum, Dictyota cervicornis, D. ciliolata, Euptilota fergusonii, Galaxaura rugosa, Halymenia durvillei, Phacelocarpus tristichus). Others are only known from a limited number of reports scattered within the Indo- Pacific region (Balliella crouanioides, Gibsmithia hawaiiensis, Predaea weldii,Hypoglossum minimum),possi bly due to their subtidal habitat or small size. Apart from those algae with a large distribution range, some species show a distinctive southern Australian - South African distribution pattern ( Carpopeltis phyllophora, Plocamium mertensii). Only Digeneopsis subopaca, originally described from Mozambique, appears to repre sent a local endemic species. Introduction coast marine provinces has been well studied and characterised by a clearly defined overlap zone The South African coastline displays a unique floral (Bolton and Stegenga 1990, Jackelmanet al. 1991), in diversity, with biota ranging from kelp beds on the contrast to the eastern border of the Agulhas (south west coast to coral reefs near the Mozambican bor coast) marine province which is less clear. Seawater der. The correlation between surface seawater tem temperature, the main defining ecological parameter peratures and shore community compositions has in the distribution of seaweeds, gradually rises from been investigated by several researchers, who have around East London to northern Kwazulu-Natal firmly established that the main defining influences (Bolton 1986). At present, it is believed that a distinct are the warm Agulhas current flowing down the east sub-tropical marine province in Kwazulu-Natal is un coast from Mozambique to the region where it meets likely, as the flora seems to comprise an eastwardly the cold Benguela current (e.g. Stephenson 1948, declining number of Agulhas-province species, these Bolton 1986, Bolton and Anderson 1990). Stephenbeing replaced largely by Indo-West pacific species son (1948) divided the South African coastline into with the increase in water temperature (Bolton and three marine provinces: the cold-temperate west Anderson 1997). It should be noted, however, that coast, warm-temperate south coast, and sub-tropical our knowledge of the marine flora of Kwazulu-Natal east coast. More recently, seaweed biogeographers, is limited. Apart from a limited number of taxa, stud although also recognising three floral provinces, have ied in detail by students of G.F. Papenfuss in Berke described them differently. The seaweed flora of the ley (California) and a field guide on the seaweeds of west coast is regarded as warm-temperate by Bolton Maputaland by Seagrief (1980), no detailed studies (1986) and Timing (1990) or cool-temperate by were available relating to Natal algae prior to 1985. Emanuel et al. (1992) and Bolton and Anderson In the eighties and early nineties R.E. Norris and co (1997), rather than cold-temperate. The presence of a authors published a series of papers on the algae of distinct sub-tropical flora on the east coast (Kwazu- Kwazulu-Natal that gave some evidence that there is lu-Natal) is not accepted by either Timing (1990) or indeed a distinct flora in the region. In total they (see Bolton and Anderson (1997). These authors consider Norris 1992 and Silvaet al. 1996 for a complete refer the seaweeds of the east coast of South Africa to be ence list) reported 63 species as new records for the westernmost extension of the large Indo-West South Africa and described 23 new species, many of Pacific tropical region, and cast doubt on the exis which are currently only known from Kwazulu- tence of a distinct sub-tropical flora in Kwazulu-Na Natal. It has also been noted that elements of the tal. Kwazulu-Natal marine algal flora have a link with The transition zone between the west and south southwestern Australia (Norris and Aken 1985, 414 O. De Clerck et al. Hommersand 1986). Kwazulu-Natal may therefore species which are newly recorded for South Africa. be more than a transition zone between the Agulhas Records on Chlorophyta have recently been pub and Indo-West Pacific floras, in that it actually consti lished separately by Leliaert et al. (2001). tutes a distinct flora with warm-temperate south western Australian affinities and a large number of endemics. Material and Methods In a joint research project conducted by the Botany Departments of the Ghent University (Bel Approximately 2400 specimens were collected over a gium) and the University of Cape Town (South period of two years (July 1998; August 1999; Decem Africa), the seaweeds of Kwazulu-Natal are being ber 1999; July-August 2000; February 2001), as a re studied from a biogeographical perspective. Several sult of a Bilateral Scientific and Technological Coop sites along the coast from Port Edward in the south eration Project between the Flemish community to Kosi Bay near the Mozambican border were sam (Belgium) and South Africa. Specimens were collect pled mainly between July 1998 and February 2001. ed at various sites distributed along the entire Kwazu The collections are now being identified and will lu-Natal coast (see Fig. 1) and were immediately eventually serve to provide a better understanding of processed as herbarium specimens, as well as being the distribution and floristic affinities of the algae partly preserved in 4 % formaldehyde/seawater. The along the Kwazulu-Natal coast. This paper reports 20 specimens, bearing serial numbers prefixed by ‘KZN’ Mozambique O Maputo Swaziland — Rabbil Rock Kosi Bay — N23 — Sexton Reef Bhanga Nek — Linkia Reef South Africa Black Rock — Tiger Reef Island Rock Mablbi i 1/4 Mileh R eef 1— 2 .7 .9 Mile R eef Sodwana Bay f— AdlamAdlai s Reef * DeepD i i f i r Sponge Cape Vidal St. Lucia Mission Rocks Mapelane Zinkwazi Shaka's Rock Durban The Bluff Treasure Beach Umkomaas Aliwal Shoal Scottsburah — Protea Banks — Orange Rocks Shelly Beach — — Boboyi Reef — Uvongo Reef Broker Reef .Trafalgar Port Edward Palm Beach 100 km Fig. 1. The coast of Kwazulu-Natal, South Africa showing the sample sites. Twenty marine benthic algae new to South Africa 415 have been deposited in GENT and BOL. Slide mate parts of the thallus and recurved branchlets; speci rial was stained in a mixture of 1 g aniline blue pow mens from exposed habitats generally form low, der, 50 mL Karo®, 45 mL distilled water, 5 mL acetic dense mats and lack slender straps. The South acid. Collections other than our own, those of R.E. African specimens represent the typical growth form Norris and co-workers (bearing serial numbers pre from exposed habitats. A major difference to previ fixed by ‘NAT’) deposited in UN and various other ous observations is the occurrence of iridescence. collectors in BOL were also examined. Herbarium Despite the examination of over 200 specimens by abbreviations follow Holmgrenet al. (1990). Digital De Clerck (1999), mainly from the East African coast images were taken, using an Olympus DP50 digital (Tanzania), iridescence was never observed. The tax camera (Melville, USA) mounted on a Leitz Diaplan onomic value and intraspecific variability of irides or Wild M10 microscope (Wetzlar, Germany). cence, however, remains poorly understood (Gaillard 1972). Results Dictyota ciliolata Sonder ex Ktitzing, 1859:12, pi. 27, fig.l. Figs 5,6 Phaeophyta Type locality: La Guaira, Venezuela. Dictyotaceae Description: Thalli are erect, to 8 cm tali, attached Dictyota cervicornis Ktitzing, 1859:11,pi. 24, fig. 2. by means of a single stupose holdfast (Fig. 6). Figs 2-4 Stolonoidal fibres are absent. Straps, 2-3 mm wide, are slender and dichotomously branched (Fig. 5).The Type locality: Key West, Florida. margins are dentate, rarely smooth, while the surface Description: Thalli form low, dense mats (Fig. 2). is always smooth. The apices are rounded. The The individual specimens are to 5 cm tali and com medulla and cortex are uniformly one-layered. Spo posed of coarse,2-3 mm wide, subdichotomous rangia are single, scattered on both surfaces, but ab straps (Fig. 4). The margins are smooth, but the sur sent in the apical dichotomies. Sporangia, 95-110 pm face is beset with acute proliferations (Fig. 3). The in diameter, are borne on a single stalk cell and are apices are obtuse. Sporangia are scattered on both not surrounded by a conspicuous involucrum. Ga surfaces, but absent in the apical dichotomies. Spo metangia were not observed. rangia, 120-135 pm in diameter, are placed mostly Ecology: Specimens were collected in intertidal solitary and are borne on a single stalk cell, surround pools of the sublittoral fringe down to -12 m. ed by a conspicuous involucrum. Gametangia were Specimens: KZN 396 and KZN 401: Mabibi not observed. In situ the colour is brown with a blue- (9.viii.l999);KZN 2182: Mabibi (13.ii.2001). greyish iridescence. Discussion: Dictyota ciliolata is characterised by its Ecology: Specimens occur in the sublittoral fringe, stupose holdfast, dentate margins and the absence of generally on wave-exposed shores. stolonoidal fibres, although the margins of some Specimens: Simons 1262 (BOL): Kosi Bay specimens can be nearly smooth (Hornig et al.