Phycological Research 1998; 46: 131-137 Cau/erpa sedoides f. geminata (Codiales, Chlorophyta) from Papua New Guinea, and a reappraisal of the different forms of C. sedoides Eric Coppejans, Olivier De Clerck and Frederik Leliaert Laboratory of Botany, Department of Biology, Gent University, K.L. Ledeganckstraat, 35-9000 Gent, Belgium SUMMARY Study of the type specimen of Caulerpa sedoides f. geminata shows that the original description and illustrations of this taxon are not correct and induce confusiono The type specimen is compared with recent collections from Papua New Guinea. A corrected and more complete description, as well as illustrations are given and a comparison is made with other Caulerpa species with opposite ramuli. Other forms of C. sedoides (f. crassicaulis, f. tasmanica, f. mixta) as well as the biogeographical distribution of this species, are discussed. Key words: Caulerpa sedoides, Caulerpales, Chlorophyta, Papua New Guinea, South Pacifico INTROOUCTION Our research on seaweeds from Papua New Guinea started in 1980 with biennial field trips. Collecting is mainly carried out along the north coast (Madang Province). The south coast (area around Motupore Island) was visited on two occasions, resulting in 520 herbarium numbers of marine macroalgae including 51 different species of Chlorophyta, 32 of Phaeophyta and 156 of Rhodophyta. Annotated and ilIustrated checklists of this area (including a map of the region) have been published (Coppejans et al. 1995a,b; Leliaert et al. 1997) or are in preparation (M illar et al. 1998). This field work led to the discovery of a peculiar species of Caulerpa from the Port Moresby area (Motupore Island) which did not fit any species known from Papua New Guinea (Coppejans and Meinesz 1988; Coppejans 1992). Apart from this species, 11 species of Caulerpa were collected in the Motupore Island area (some incl ud ing different growth forms or ecads, Coppejans et al. 1995a): C. biserrulata Sonder, C. elongata Webervan Bosse, C. lentillifera J. Agardh, C. manorensis Nizamuddin, C. microphysa (Weber-van Bosse) J. Feldmann, C. opposíta Coppejans and Meinesz, C. racemosa (ForsskElI) J. Agardh (incl. ecad laetevirens, ecad peltata, ecad racemosa) , C. serrulata (Forsskal) J. Agardh emend. B0rgesen, C. sertularioides (S.G. Gmelin) Howe, C. taxifolia (Vahl) C. Agardh, C. webbiana Montagne (incl. ecad disticha). In an early study phase, the presumed new species had provisionally been named C. micropposita (Coppejans and De Clerck 1996) beca use of its similarity to C. opposíta, differing from the latter by its smaller size. However, after comparison with other species, it beca me apparent that C. micropposíta actually represents a growth form of C. sedoides C. Agardh. In the present study, critical examination of type specimens of several growth forms of C. sedoides allowed us to give a clear circumscription of this variable species. MATERIALS ANO METHOOS Field work was carried out from 4 to 6 July 1986 (by Coppejans) and from 18 July to 5 August 1994 (by Coppejans and De Clerck) from the Motupore Research Station (Port Moresby area, Coppejans et al. 1995a; map 1). The specimens of C. sedoides f. geminata (Harvey) Weber-van Bosse were collected by snorkeling and SCUBA diving. Most of them were pressed and dried as herbarium specimens, part of them was preserved-in 5% formal in/seawater. The internal structure was observed on the preserved as well as on rehydrated herbarium fragments; line drawings were made with the aid of a camera lucida mounted on a Wild M7 dissecting microscope. The following type specimens were studied: C. sedoides f. geminata (Iectotype: Rottnest Island 1854, Harvey n0214, TCD), C. sedoides f. crassicaulis (Iectotype: Friendly Islands, Harvey n072, LD 16818, syntype: Whitsunday Island, Qld, Kilner s.n., LD 16823), C. sedoides f. tasmanica (holotype: ad oras Tasmania, Gunn s.n., LD 16821). RESULTS The numerous specimens from the Motupore region have an extremely homogeneous morphology, hardly showing variation (Figs 1,3) and being very similar to Communicating editor: K. Okuda. Received 3D November 1996; accepted 13 February 1998. 132 E. Coppejans Figs 1,2. area). Caulerpa sedoides f. geminata (specimen HEC 10187). et al. 1. General habit of a specimen from Papua New Guinea (Port Moresby 2. Detail of some typical assimilators. the previously mentioned type material of C. sedoides f. geminata. These allowed us to give a detailed description of this formo Thallus epilithic, forming dense mats. Smooth rhizomes entangled, frequently branched, closely appressed to the substrate, 1 mm in diameter. Rhizoidal branches very irregularly spaced from only a few mm to several cm distant, 1-2 (-4) mm long. Assimilators (Figs 2, 4-7) dark to medium green, rather densely set: 0.5-1 (-2.5) cm apart, slightly recurved alternately (Fig. 12) to one or the other side of the rh izome, resulting in V-shaped rows; rachis simple (very rarely branched once; Fig. 8), terete to slightly compressed, unarticulated (no ring-like constrictions) but composed of successive wedge-shaped parts (Figs 10,11), fully grown rachis (1-) 1.5-2.5 (- 4) cm high (maximum 2 cm in the type material), varying in diameter by their shape (1 mm at the base of the segment, 1.75-2 mm at the insertion point of the ramuli), sometimes basally bare and terete only over a very short distance (25 mm), bearing two opposite rows of densely set vesicular ramuli, resulting in an extremely regular shape and a total frond width of 5-7 mm. Ramuli circular to broadly oval in surface view (Fig. 11), (1.5-) 2 mm in diameter (1.25-1.75 mm in the type material), subspherical to si ightly dorsiventrally compressed (Figs 12,13), basally constricted, sessile, (sub)opposite, densely set, rarely contiguous (sometimes slightly overlapping in the type specimen), slightly acropetally directed; six to 10 (but up to 16) pairs of ramuli per rachis. Chloroplasts with a single pyrenoid¡ small, elongate amyloplasts very numerous (Fig. 14). Specimens examined: lectotypus Harvey n0214, TCO: W. Australia, Rottnest Island; HEC 10187: Papua New Guinea, Port Moresby area, Motupore Island, south (seaward) coast, 2117/1994, on coral fragments on sand, outer reef slope, -3/-6 m; HEC 10280: Papua New Guinea, Port Moresby area, Loloata Island, southeast reef, 27/7/1994, on coral fragments on sand, outer reef slope, -10/-15 m; HEC 10371: Papua New Guinea, Port Moresby area, Loloata Island, western end of the reef platform, 31/7/1994, epilithic on dead coral of the outer reef slope, -5/-10 m, locally forming large, dense patches of up to 1 m 2 • DISCUSSION Harvey (1855, p. 564) originally described C. geminata based on a specimen from Rottnest Island, Western Australia. After having examined more material, Harvey (1859, pI. LXXII, figs 2,3) noticed a complete transition between C. geminata and C. sedoides C. Agardh. He, therefore, reduced C. geminata to a variety, C. sedoides varo geminata (Harvey) Harvey. In the latter publication he also iliustrated both forms. Later Weber-van Bosse (1898, p. 387) considered C. geminata as a forma of C. sedoides. The type specimen, Harvey n0214 contains two thalli (Fig. 15), the upper left one belonging to f. sedoides, the lower right one to f. geminata (Fig. 16). It is as- 133 A reappraisal of Caulerpa sedoides Figs 3-8. Caulerpa sedoides f. geminata from PNG (HEC 10187). assimilators. torso Fig.9. 6. Medium height assimilators. 3. Part of a typical specimen. 4, 5. Parts of the thallus with long 7. Apical part of a stolon with young assimilators. Caulerpa opposita. Assimilator with markedly stipitate branchlets. 8. Ramified assimila- E. Coppejans et al. 134 ' Figs 10-14. geminata. Caulerpa sedoides f. .. : ..... : : :" .... 10. Rhizome with an as- similator in front view. 11. Detail of the segmented rachis and opposite, sessile ramuli. 12. Side view of an assimilator with slightly recurved rachis. 13. Detail of the slightly dorsiventrally compressed ramuli on the rachis. 14. Plastids composed of two kinds: chloroplasts with a pyrenoid and amyloplasts (black particles). sumed that Harvey based his original description on this f. geminata specimen, which is, therefore, selected as a lectotype. Accurate study of this specimen revealed that Harvey's illustration (1859, pI. LXXII, figs 3,4) is not entirely correct. The type has subcircular ramuli (instead of obovoid) and they are inserted on slightly broadened parts of the rachis (instead of at the constrictions of the rachis), so the drawings cause confusion. Moreover the 'constrictions', which are due to the wedge-shaped parts of the rachis, not to annular constrictions, are not as pronounced as in Harvey's drawings. Because of these articulations, Weber-van Bosse (1898) placed C. sedoides in the section Opuntioideae J. Agardh. The herbarium specimen does not allow the reconstruction of the three-dimensional structure of the ramuli which could be spherical or compressed. Caulerpa sedoides f. sedoides and C. sedoides f. geminata were both described from Australia (Kent Island, Victoria and Rottnest Island, respectively) and are characterized by ovoid to somewhat elongate, vesiculate ramuli which are either placed radially or distichously on the rachis (pers. obs.). The arrangement of the ramuli is usually loose and irregular. Australian representatives of the C. sedoides complex often show intergrades between a radial and distichous arrangement of the ramuli, frequently even on the same frond. Moreover, the rachis is often branched (Womersley 1984, p. 268). Based on these characters, we originally concluded (Coppejans and De Clerck 1996) that our specimens from Papua New Guinea belonged to a new species, provisionally called C. micropposita beca use of the homogeneously circular to broadly oval surface view of the ramuli and their position on the broadened parts of the rachis (instead of at the constriction points). Study 135 A reappraisal of Caulerpa sedoides 1 cm 18 21 19 - 1 cm Figs 15-21. Different forms of Caulerpa sedoídes. right (arrow), C. sedoídes f. gemínata. an assimilator. 15. Type specimen Harvey no. 214: upper left, Caulerpa sedoídes f. sedoídes; lower 16. Detail of the lectotype. 19. Lectotype of C. sedoídes f. crassícaulís. 17, 18. Type specimen of C. sedoídes f. tasmaníca. 20,21. Syntype of C. sedoídes f. crassícaulís. 18. Detail of 21. Detail of C. sedoídes f. crassícaulís. of the type material of C. sedoides f. geminata convinced us that we had collected specimens of this taxon in its most characteristic growth formo No intermediate growth forms of C. sedoides f. sedoides were found among specimens collected from different biotopes in the Port Moresby area. This would rather confirm the first impression of Harvey (1859) who states that 'Our varo B (= geminata) in its typical state, looks so unlike the common form (= varo sedoides) that I at first took it for a distinct species; but specimens subsequently obtained showed a complete passage into the ordinary C. sedoides'. Harvey's herbarium sheet with the type specimen (n° 214 right down) contains another specimen of C. sedoides f. geminata (n° 559) with circular E. Coppejans et al. 136 to obovate ramuli; the other specimens (n° 214 left up, n° 559a and unnumbered) belong to C. sedoides f. sedoides with obovate ramuli in all directions along the rachis. No intermediates are present on this sheet. Caulerpa fergusonii Murray is similar to C. sedoides f. geminata, but the type specimen in Leiden (L 930.139-10; Ferguson Ceylon Algae n° 415) exhibits a clearly articulated rachis with marked, ring-like constrictions and ovoid to clavate ramuli (pers. obs.) which also have been described and illustrated by Murray (1891, p. 212, pI. 53, fig. 1), Weber-van Bosse (1898, p. 389, pI. 34, fig. 12), Taylor (1967, p. 48, fig.3) Kajimura (1975, p. 24) and Coppejans and Prud'homme van Reine (1992a, p. 690, figs 1D,E,13A,B). Weber-van Bosse (1913, p. 112, fig.29) illustrated specimens of C. fergusonii without articulations, the illustration showing circular, dorsiventrally compressed, paired ramuli, looking like young C. sedoides f. geminata specimens. Examination of these specimens (L 937.333-88) in Leiden confirmed their identification as C. fergusonii. Caulerpa zeyheri Kützing is markedly smaller and more elegant than C. sedoides f. geminata the erect branches being only 0.8-1.3 cm high according to Sartoni (1978, p. 412, fig. 5D), the ramuli are pyriform and successive pairs are overlapping. The specimens of C. zeyheri reported by Taylor (1967) from Mozambique correspond very well with our material from Tanzania (Zanzibar), with a marked naked basal part of the rachis and turbinate to pyriform ramuli, but are different from C. sedoides f. geminata beca use of the absence of pyrenoids. The general morphology of Caulerpa opposita Coppejans and Meinesz is quite similar to C. sedoides f. geminata but the former species is much coarser (Fig. 9). No specimens with intermediate sizes between C. opposita and C. sedoides f. geminata have been found. Both species have plastids with a pyrenoid. Caulerpa buginense Verheij and Prud'homme van Reine (1993, p. 392) also is somewhat similar to C. sedoides f. geminata, but the ramuli of the former species are flat and successive pairs of ramuli are markedly overlapping. The illustrations of C. manorensis Nizamuddin by Nizamuddin (1964, p. 216) and Shameel and Shaukat (1992) appear to be similar to C. sedoides f. geminata but the former is different from the latter by having a compressed rachis and branchlets. Apart from C. sedoides f. geminata, three more forms have been described: C. sedoides varo tasmanica J. Agardh (1873, p. 40) after material from Tasmania and later considered as a forma by Weber-van Bosse, C. sedoidesf. tasmanica (J.Agardh) Weber-van Bosse (1898, p. 387). Examination of the type specimen (Figs 17,18) proves it to be a rather lax growth form of C. sedoides f. sedoides and easi Iy fits in the morphological range of this variable species. Caulerpa sedoides varo crassicaulis J. Agardh was described after a Harvey specimen from Tonga (Friendly Islands) and material from Whitsunday Island, Queensland. Weber-van Bosse (1898, pp. 387-380) selected the Harvey specimen as lectotype (Fig. 19) and reduced this variety to a forma, C. sedoides f. crassicaulis (J. Agardh) Weber-van Bosse. However, re-examination of the type material revealed that this forma did not belong to the C. sedoides complex, but that it should be considered as C. lentillifera J. Agardh varo kilneri (J. Agardh) Weber-van Bosse. The most conspicuous character differentiating C. sedoides and C. lentillifera lies in the shape and placement of the ramuli. The ramuli of C. lentillifera are absolutely spherical whereas those of C. sedoides or either oblongate or dorsoventrally compressed¡ moreover, they are placed on fairly regular, dense, longitudinal rows in the former (Coppejans and Meinesz 1988, figs 39,40), whereas they are generally loosely and irregularly placed in the latter (Womersley 1984, p. 255). The variety kilneri is characterized by short, subconical pedicels, whereas the pedicels of the typical C. lentillifera specimens are much longer and subcylindrical (Cribb 1958, pp. 213-214). The morphology of the pedicel does not differentiate between C. sedoides and C. lentillifera varo kilneri, nor does the presence of a pyrenoid. It is noteworthy that the original description of C. lentillifera varo kilneri was based on a specimen collected by Kilner from Whitsunday Island, the syntype locality of C. sedoides f. crassicaulis (Figs 20,21). Svedelius (1906, pp. 139-140) reported C. sedoides f. crassicaulis from Sri Lanka, but it should be confirmed whether the specimen effectively represents C. sedoides or C. lentillifera. A fourth forma was also described by Svedelius (1906, p. 140) from Sri Lanka, C. sedoides f. mixta, which seems to be characterized by a slender thallus and ramuli of variable size and shape, as it normally is in C. sedoides. According to Silva et al. (1996) C. sedoides f. geminata has been reported from Australia and Indonesia. The collection of C. sedoides f. geminata from Papua New Guinea extends the biogeographical distribution northwards. Caulerpa sedoides f. sedoides is mentioned from Australia, India, Indonesia, Mauritius, Sri Lanka (Silva et al. 1996), but some records (e.g. from Indonesia) represent growth forms of Caulerpa racemosa (Prud'homme van Reine et al. 1996, p. 87) or C. lentillitera. Up to recently, we personally never collected it during field trips in other parts of the Indo-Pacific: Indonesia (Coppejans and Prud'homme van Reine 1989, 1992a,b), Seychelles (Coppejans et al. 1994), Kenya (Coppejans and Beeckman 1989, 1990). Its observation at Zanzibar (HEC 12019: Tanzania, Zanzibar, Paje, 23/7/1997, epi lithic, seaward slope of reef, infralittoral fringe) extends its distribution to the East coast of Africa. ACKNOWLEDGEMENTS We are very grateful to J. Rewald for the excellent local organization of our stay on Motupore Island in 1994. A reappraisal of Caulerpa sedoides 137 We are also indebted to W. F. Prud'homme van Reine for the help during our stays at the Rijksherbarium in Leiden. The curator of the Herbarium of TCD is acknowledged for the loan of the the type-specimen of C. sedoides f. geminata, Per Lassen (LD) for the loan of the type-specimens of C. sedoides f. crassicaulis and f. tasmanica, and the referees for their constructive remarks. O. De Clerck is research assistant of the Fund for Scientific Research-Flanders (Belgium) (FWO). This research was sponsored by the Fund for Scientific Research-Flanders (Belgium: research-project nos 32.9008.90, 32.0009.92 and 3G.0024.96). Coppejans, E. and Prud'homme van Reine, W. F. 1992b. Sea- REFERENCES Kajimura, M. 1975. On the fertile stage of Caulerpa fergusonii Agardh, J. 1873. Till algernes systematik. Nya Bidrag. Lunds Universitets Ars-Skrift, Afdelningen Fr Mathematik Och Naturvetenskap 9: 71 pp. Coppejans, E. 1992. Marine algae of Papua New Guinea (Madang Prov.) 2. A revised and eompleted list of Caulerpa (Chlorophyta, Caulerpales). Blumea 36: 383-410. Coppejans, E. and Beeekman, 1. 1989. Caulerpa seetion Sedoideae (Chlorophyta, Caulerpales) from the Kenyan eoast. Nova Hedwigia 49: 381-93. Coppejans, E. and Beeekman, 1. 1990. Caulerpa (Chlorophyta, Caulerpales) from the Kenyan eoast. Nova Hedwigia 50: 111-25. Coppejans, E. and De Clerek, O. 1996. 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