KETO E. MSHIGENI & REGINE JAHN Eucheuma (Rhodophyta, Gigartinales) in the W Indian Ocean region - notes on collections kept in Berlin-Dahlem and Hamburg Abstract Mshigeni, K. E. & Jahn, R.: Eucheuma (Rhodophyta, Gigartinales) in the W Indian Ocean region - notes on collections kept in Berlin-Dahlem and Hamburg. - Willdenowia 25: 399-407. 1995. - ISSN 0511-9618. A survey on the Eucheuma collections from the W Indian Ocean region kept at B and HBG is given; notes on the distribution of E. denticulatum, E. odontophorum and E. platycladum are added and the characters distinguishing E. odontophorum from E. platycladum listed. Introduction The red algal genus Eucheuma J. Agardh (Gigartinales, Solieriaceae) is economically the most important seaweed in the western Indian Ocean region. Some of its species are exported by Tanzania (Anderson 1953; Mshigeni 1973, 1987) and Madagascar (Mollion, Andriantsiferana & Sekkal 1990; Rabesandratana & Rabesandratana 1992) for use as a source of carrageenan (Doty 1973, 1988; Mshigeni & Semesi 1977). The commercial importance of Eucheuma in the region is likely to increase in the near future with the introduction and successful assimilation of its cultivation technology in Tanzania's rural communities along the coast (Mshigeni 1992). This Eucheuma farming technology has been pioneered by M. Doty and V. Alvarez (Doty 1973) in the Indo-Pacific region. However, the various species of Eucheuma in the W Indian Ocean region are still imperfectly known (Doty 1988; Mollion, Andriantsiferana & Sekkal 1990), and there is a need for a detailed study of their taxonomy and distribution. Most of the earlier authors, who validated the names of Eucheuma species from the region, based their descriptions on dead specimens or just fragments. Often the samples were collected by non-specialists or short-term visitors, who did not record field data and the morphological variability of the sampled plants in their natural habitats. Therefore, they could not know to what extent the morphological characters had been influenced by the environment (e.g. exposure to waves, intertidal stress, grazing) or by age phenomena. The current circumscription of the Eucheuma species of this region (Mshigeni 1984, 1987) were reached after extensive field studies of these taxa in East Africa and Mauritius, and by comparing the collections with specimens from other herbaria (listed also in Doty 1988). The present study focusses on the historical Eucheuma material from the W Indian Ocean region in the herbaria of Berlin-Dahlem (B) and Hamburg (HBG). Results and discussion Our results are summarized in two tables. Tab. 1 contains the details of all Eucheuma specimens of African origin that were found in the herbaria investigated.Tab. 2 lists published records of distribution of if cut at a distance and axiferous when cut close to the apex. He has revised the sectional arrangement of the various species of Eucheuma and separated some of the taxa into the new genus Kappaphycus Doty, which encompasses species characterised by the presence of kappa carrageenan (e.g. K. cottonii, K. inerme). But he does not place Eucheuma platycladum under Kappaphycus, even though the species produces kappa carrageenan preponderantly (see also Doty & Santos 1978; Mshigeni & Semesi 1977, Doty 1988: 204). Since the precise chemical analysis of the carrageenan types in the majority of the Eucheuma species reported in the region is still to be done, and since some findings are not adequately conclusive, we have retained the old genus name. Eucheuma denticulatum (Burman) Collins & Hervey The locality of the two specimens kept at B, i.e. Cape of Good Hope or just Cap., is doubtful, since the southern tip of Africa is believed to be too cold for Eucheuma. As shown in Tab. 2, and pointed out by Mshigeni (1979, 1984, 1987) and Jaasund (1976, 1977), the species is widely distributed in East Africa. Its range has recently been extended to Madagascar (Mollion, Andriantsiferana Eucheuma species from the western Indian Ocean region; in addition to the cited species, Doty (1988) recognises the occurrence of Eucheuma serra J. Agardh in Mauritius. The various species of Eucheuma were arranged by Weber-van Bosse (1928) into two sections: section Axifera encompasses species with a central axis of relatively small and densely packed cells (e.g. E. denticulatum, E. serra, E. horridum); section Anaxifera embraces taxa (e.g. E. cottonii, E. platycladum) whose fronds lack a definite central axis. But Doty (1988: 204-205) has cautioned that transverse sections of the same thallus may appear anaxiferous & Sekkal 1990; Rabesandratana & Rabesandratana 1992). In addition we found a box with dried specimens of E. denticulatum which lacked a label; this might be some of the material which Schmitz (1895: 139) referred to as E. spinosum. E. odontophorum Børgesen The record from Lamu in Kenya (Fig. 1) represents the northernmost locality of this species. Doty (1988) has also documented its occurrence in Mauritius but writes: "... Not enough is known about E. odontophorum to circumscribe it in detail. The type specimen ... and the only other collection seen ... is of thin axiferous, strap-shaped fragmentary blades, ornamented only by lateral teeth, so as to look like a juvenile form of E. platycladum". He points out that the placement of E. platycladum in the sections is unsatisfactory, since there are mixed reports of their axes being anaxiferous as well as axiferous. Earlier Weber-van Bosse (1928: 417) was not sure of the placement of this species in the section Anaxifera since she was unable to locate the type specimen in Berlin. E. platycladum Schmitz In our search for Eucheuma specimens in Berlin, we detected a small cardboard box containing a dried specimen (Fig. 2A) with spinulose and compressed, anastomosed axes, which perfectly fitted our conception of E. platycladum Schmitz. The handwritten label bears the collectors name, the number and type locality indicated by Schmitz (1895: 152) for E. platycladum: Holst 1340, Dar es Salaam. But the species is labelled Eucheuma spinosum (L.) J. Agardh as Schmitz (1895: 152) explains: "This Eucheuma species is quite a big plant of peculiar habit. I have already seen several specimens of it, and I am astonished that nobody has described it as a separate species. I found it [the type specimen] named E. spinosum, but it has no similarity to this species; it rather resembles the Southwest-Australian E. speciosum (Sond.) J. Ag., but differs also slightly from this species". Since Schmitz died unexpectedly (see footnote in Schmitz 1895: 137), the label on the specimen was apparently not changed. The cardboard box as well as the printed label with the locality "D.[eutsch] Ostafrika" (German East Africa) indicates that this specimen was used as exhibition material, some of which survived the 1943 bombing of the Botanical Museum Berlin-Dahlem. This would also explain why Weber-van Bosse (1928: 417) was unable to locate the type. If duplicates mounted on herbarium sheets with correct labels had existed, she would have seen them; but they would have been destroyed together with those of E. inerme. What a coincidence that the re- discovery date, December 1992, was exactly a century after Holst had collected the material in December 1892 (Schmitz 1895: 138)! Besides material used for exhibition purposes in the Botanical Museum Berlin- Dahlem before the Second World War most of the wet collections remained extent; among them we found another specimen of E. platycladum collected by A. Voeltzkow in 1903 from the "Tamatave Riff", Madagascar (Fig. 2B, Tab. 1) which confirms the recent report by Mollion, Andriantsiferana & Sekkal (1990) on the existence of E. platycladum in Madagascar, thus extending its geographical range beyond East Africa. Not a single specimen of this species was found pressed onto herbarium sheets. This might be due partly to the inherent difficulties with drying its thalli, because of the cartilaginous nature of its fronds, the anastomosing habit, and the high phycocolloid content. The coastal inhabitants in Tanzania refer to the seaweed as mwani-mkate, meaning bread-like seaweed, or mwani-kisahani, referring to its plate-like appearance. Fronds of the alga form expansive cake- like masses over the substrata, sometimes forming cushions which weigh several kilogrammes. We do not share the view that the morphological differences of E. odontophorum and E. platycladum are not clear-cut (Doty 1988: 198). Both species have dorsiventrally compressed fronds and are spinulose, but there are differeces: the axes of E. odontophorum are axiferous, those of E. platycladum anaxiferous; the fronds of E. odontophorum show distinct segmentation (Fig. 1) those of E. platycladum lack constrictions along the axes; the younger axes of E. odontophorum are almost cyclindrical and the older sub-cylindrical, the axes of E. platycladum exhibit a stronger tendency of flattening and anastomosing, even on the relatively young branchlets; the axes of E. odontophorum are terminally downwardly arched (Mshigeni 1979, fig. 11; Mshigeni & Semesi 1977, fig. 5), this is not so distinct in the fronds of E. platycladum. Acknowledgements Thanks are due to the Institut für Allgemeine Botanik, University of Hamburg, for the use of the research facilities; to Dr. B. Zimmer for useful suggestions, and to B. Schreiber for assisting with the photographic work. The senior author is most grateful to the German Academic Exchange Service (DAAD) for financial support. References Agardh, J. G. 1892: Analecta algologica 1. - Lund. Anderson, G. W. 1953: A note on the seaweed resources of Zanzibar Protectorate. - Proc. Int. Seaweed Symp. 1: 102-103. Børgesen, F. 1943: Some marine algae of Mauritius. III. Rhodophyceae, Part. 2. Gelidiales, Cryptonemiales, Gigartinales. - Biol. Meddel. Kongel. Danske Vidensk. Selsk. 19(1). – 1950: Some marine algae of Mauritius. Additions II. - Biol. Meddel. Kongel. Danske Vidensk. Selsk. 18(11). Dickie, G. 1875: On the algae of Mauritius. - J. Linn. Soc., Bot. 1: 190-202. Dixon, P. S. 1962: Taxonomic and nomenclatural notes on the Florideae III. - Bot. Not. 115: 245-260. Doty, M. S. 1973: Farming the red seaweed Eucheuma for carrageenans. - Micronesica 9: 59-73. – 1988: Prodromus ad systematica Eucheumatoiderum: a tribe of commercial seaweeds related to Eucheuma (Soleriaceae, Gigartinales), p. 159-207. - In: Abbott, I. A. (ed.), Taxonomy of economic seaweeds, with special reference to some Pacific and Caribbean species 2. - La Jolla, Calif. – & Santos, G. A. 1978: Carrageenans from tetrasporic and cystocarpic Eucheuma species. - Aquatic Bot. 4: 143-149. Harvey, W. H. 1834: Notice on a collection of algae communicated to Dr. Hooker by the late Mrs. Charles Telfair from Cap Malheureux in Mauritius. - J. Bot. (Hooker) 1: 147-157. Jaasund, E. 1976: Intertidal seaweeds in Tanzania: a field guide. - Tromsø. – 1977: Marine algae in Tanzania VII. - Bot. Mar. 20: 415-425. 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(eds.): Proceedings of the First International Workshop on Sustainable Seaweed Resource Development in Sub-Saharan Africa, Windhoek, Namibia. - [s.l.]. – & Semesi, A. K. 1977: Studies on carrageenans from the economic red algal genus Eucheuma in Tanzania. - Bot. Mar. 20: 239-242. Rabesandratana, H. D. & Rabesandratana, R. N. 1992: Seaweeds and their uses in Madagascar, p. 297-307. - In: Mshigeni, K. E. et al. (eds.), Proceedings of the First International Workshop on Sustainable Seaweed Resource Development in Sub-Saharan Africa, Windhoek, Namibia. - [s.l.]. Schmitz, F. 1895: Marine Florideen von Deutsch Ost-Afrika. - Bot. Jahrb. 21: 137-177. Sonder, W. 1879: Algae, p. 79-85. - In: Kersten, O., Baron Carl Claus von den Deckens Reisen in Ost-Afrika in den Jahren 1859-1865 3(3). - Leipzig. Weber-van Bosse, A. 1913: Marine algae, Rhodophyceae of the Sealark- Expedition collected by Mr. J. Stanley Gardiner, M.A. - Trans. Linn. Soc. London, ser. 2, Bot. 8: 105-142. – 1928: Liste des algues du Siboga. IV. Part 3. Gigartinales et Rhodymeniales, p. 393-533. - In: Weber, M. (ed.), Siboga Exped. Monogr. 59d. Yarish, C. & Wamukoya, G. 1990: Seaweeds of potential economic importance in Kenya: field survey and future prospects. - Hydrobiologia 204/205: 339-346. Addresses of the authors: K.E. Mshigeni, Department of Botany, University of Namibia, Private Bag 13301, Windhoek, Namibia. R. Jahn, Botanischer Garten und Botanisches Museum Berlin-Dahlem, Freie Universität Berlin, Königin-Luise-Str. 6-8, D-14195 Berlin. Tab. 1: Eucheuma specimens from the W Indian Ocean region in B and HBG. Locality//Collector//Date//Voucher//Remarks Eucheuma denticulatum Cape of Good Hope//[Herb. Schiffner]//Not recorded//B: Algae 15031//Non- compressed, spinulose, verticillate Cape of Good Hope//Not recorded//Not recorded//B: Algae 23778//Non- compressed, spinulose, verticillate E. horridum Mauritius//not recorded//not recorded//B: Algae 15042// Spinulose, non-com- pressed, some of the spines elongated into branchlets, irregularly arranged Madagascar//herb. Wollny; herb. Th. Reinbold//Not recorded//HBG: H.H.10//Fronds slender, spinulose, non-compressed, spines not arranged in regular whorls E. odontophorum Kiu Island Lagoon, Kenya// P.J. Greenway 9388 & S.P. Rawlins//13.10.1957//B: Algae 33866, 34190//Fronds clad with spines, semi- compressed, with many constrictions along the axes E. platycladum Dar es Salaam, Tanzania// Holst 1340//12.1892//B: Algae 36507//Type; single specimen, spinulose, axes dorsiventrally compressed, constrictions along the axes not distinct Tamatave Riff, Madagascar//Voeltzkow//1903//B: Algae 37362 (wet)//Fronds clad with spines, dorsiventrally compressed, constrictions along thallus axes not distinct E. striatum Zanzibar//Stuhlmann//1889?//HBG: H.H. 21//Type (fragment) Pemba Island//Voeltzkow//1903//B: Algae 29 068//Several specimens, non- spinulose, non-compressed, with acuminate branches Tab. 2: Published records of Eucheuma species in the W Indian Ocean region (see Dixon (1962) and Mshigeni (1987) for synonymy and re-identifications), *= records need confirmation. Locality//Reference//Name recorded//Collector//Date Eucheuma cottonii Mascarene Ridge//Weber-van Bosse (1913)//E. cottonii//J.S. Gardiner//Sealark- Expedition Tanzania//Mshigeni (1973; 1979)//E. okamurai//K.E. Mshigeni//1969 Tanzania//Mshigeni & Semesi (1977)//E. okamurai//K.E. Mshigeni//1969 Tanzania//Jaasund (1976, 1977)//E. okamurai//E. Jaasund//1966-69 Kenya*//Yarish & Wamukoya (1990)//E. cottonii E. denticulatum Mauritius//Dickie (1875)//E. spinosum//Pike//1869 ? Zanzibar//Sonder (1879)//E. spinosum//A. Roscher//1859 Zanzibar//Schmitz (1895)//E. spinosum////?1885 Tanzania//Schmitz (1895)//E. spinosum//C. Holst//1892 Tanzania//Mshigeni (1973, 1979)//E. spinosum//K.E. Mshigeni//1969 Tanzania//Mshigeni & Semesi (1977)//E. spinosum//K.E. Mshigeni//1969 Tanzania//Jaasund (1976), (1977)//E. spinosum//E. Jaasund//1966-69 E. horridum Mauritius//Harvey (1834)//Sphaerococcus horrida //Ch. Telfair//18?? Mauritius//Dickie (1875)//E.horridum//Pike//1869? Mauritius//J. Agardh (1892)//E. jugatum Mauritius//Børgesen (1943)//E. serra//Th. Mortensen//1929 Mauritius//Børgesen (1943, 1950)//E. jugatum //Th. Mortensen//1929 Mauritius//Børgesen (1943, 1950)//E.horridum//Th. Mortensen//1929 Tanzania//Mshigeni (1987)//E.horridum//K.E. Mshigeni//1969 Kenya//Yarish & Wamukoya (1990)//E.horridum Madagascar*//Mollion, Andriantsiferana & Sekkal (1990)//E. denticulatum Madagascar*//Rabesandratana & Rabesandratana (1992)//E. denticulatum E. odontophorum Mauritius//Dickie (1875)//E. spinosum//Pike//1869? Mauritius//Børgesen (1943)//E. odontophorum//Th. Mortensen//1929 Mauritius//Børgesen (1943)//E. speciosum (Sonder) var. mauritiana//Th. Mortensen //1929 Tanzania//Mshigeni (1973; 1979)//E. speciosum var. mauritiana//K.E. Mshigeni//1969 Tanzania//Mshigeni & Semesi (1977)//E. speciosum var. mauritiana//K.E. Mshigeni//1969 Tanzania//Jaasund (1976, 1977)//E. speciosum var. mauritiana//E. Jaasund//1966-69 Tanzania//Mshigeni (1987)//E. odontophorum//K.E. Mshigeni//1969 Mauritius//Doty (1988)//E. odontophorum//M. Doty Eucheuma platycladum Tanzania//Schmitz (1895)//E. platycladum//C. Holst//10.1892 Tanzania//Mshigeni (1973; 1979)// E. platycladum //K.E. Mshigeni//1969 Tanzania//Mshigeni & Semesi (1977)//E. platycladum//K.E. Mshigeni/1969 Tanzania//Jaasund (1976, 1977)//E. platycladum//E. Jaasund//1966-69 Tanzania//Mshigeni (1987)//E. platycladum//K.E. Mshigeni//1969 Tanzania//Doty (1988)//E. platycladum//G.F.Papenfuss & R.F. Scagel//1962 Tanzania//Doty (1988)//E. platycladum//K.E. Mshigeni//1969 Madagascar//Mollion, Andriantsiferana & Sekkal (1990)//E. platycladum Madagascar//Rabesandratana & Rabesandratana (1992)//E. platycladum E. striatum Zanzibar//Schmitz (1895)//E. inerme////1885 Tanzania//Schmitz (1895)//E. inerme//C. Holst//1885 Zanzibar//Schmitz (1895)//E. striatum//F. Stuhlmann//1888-90 Tanzania//Mshigeni (1973, 1979)//E. striatum//K.E. Mshigeni//1969 Tanzania//Mshigeni & Semesi (1977)//E. striatum//K.E. Mshigeni//1969 Tanzania//Jaasund (1976, 1977)//E. striatum//E. Jaasund//1966-69 Madagascar//Mollion, Andriantsiferana & Sekkal (1990)//E. striatum Madagascar//Rabesandratana & Rabesandratana (1992)//E. striatum