The First Occurrence of the Green Alga Paralella Nova-Zealandiae (Chlorophyta, Tetrasporales) From MichiganSkip other details (including permanent urls, DOI, citation information)
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Page 105 ï~~2007 THE MICHIGAN BOTANIST 105 THE FIRST OCCURRENCE OF THE GREEN ALGA PARALELLA NOVA-ZEALANDIAE (CHLOROPHYTA, TETRASPORALES) FROM MICHIGAN Daniel E. Wujek Department of Biology Central Michigan University Mt. Pleasant, MI 48859 ABSTRACT The green alga Parallela nova-zealandiae is described from two Michigan locations. A comparison with and its possible relationship to the genus Radiofilum are discussed. KEYWORDS: Parallela, Tetrasporales, Radiofilum, green algae INTRODUCTION There are numerous genera of green algae (Chlorophyta) living in freshwater habitats. Reports of their distribution in North America have been scattered throughout the algal literature for a long time including the work of Prescott (1962) for the western Great Lakes. These reports been summarized only recently for North America (Wehr & Sheath 2003). This paper reports the occurrence in Michigan of the green alga Parallela novae-zealandiae Flint, a species first described from New Zealand (Flint 1974). METHODS AND MATERIALS Oak leaves and small twigs with attached Parallela were collected from Stoney Lake, Kalamazoo Co. and the north arm of Lake Geneserath, Beaver Island, Charlevoix Co., Michigan in late June 1968 and early July 1990, respectively. Observations were made with an AO or Zeiss Photoscope II microscope from both freshly collected material and from short term cultures grown in soil water extract or Bold's Basal Medium (Bold 1967) with additional soil water extract. Attempts to maintain cultures for extended periods failed; cultures no longer survive. RESULTS AND DISCUSSION An alga, first determined as Homospora transversalis de Br6bisson (1839, 1844) was collected in late June 1968 from Stoney Lake. The algae grew attached to the under surface of a floating dead oak leaf. The largest plant was visible to the unaided eye and smaller ones with a hand lens. The alga was later identified as Parallela novae-zealandiae Flint, an organism first described from the South Island, New Zealand (Flint 1974). It was later reported from the North Island, New Zealand (Taylor 1975). Subsequent reports include Denmark (Chris
Page 106 ï~~106 THE MICHIGAN BOTANIST Vol. 46 tiansen 962) as Radiofilum transversale (de Brdbisson) Christiansen, the States of Minas Gerais and Rio de Janeiro, Brazil, South America (Santa Anna et al. 1979), Kansas, U.S.A. (Reinke 1983), and most recently Australia (Entwisle 1989; Entwisle & Skinner 2001). The alga is filamentous to slenderly clavate and gelatinous. Young plants have a uniseriate arrangement of cells enclosed by a continuous gel equal in thickness to the cell diameter (Fig. 1). The attached end appears to remain uniseriate for a length of six to eight cells during early growth. Above this area longitudinal divisions produce a biseriate condition (Fig. 2) and still higher additional longitudinal divisions produce a tiered arrangement of four cruiciately arranged cells (Fig. 3). Continued intercalary divisions in which each cell and its progeny accomplish three planes of division produced tiered packets of 16 or more cells. Through secretions of gel by each cell they eventually spread apart, at first laterally in the plane of the tier, then through further division and gel secretion the displacement becomes irregular. At the apex of the plant, cells and small groups of cells are scattered irregularly throughout (Fig. 4). During this growth, the outer gel of the plant may become two to three cell-diameters thick and the plant as a whole becomes clavate in shape (Fig. 5). Each cell has a continuous, thick wall distinct from the surrounding gel (Fig. 6). Within is a parietal, bowl-shaped chloroplast that closely encloses the protoplast but leaves a small open area interpreted as the morphological anterior pole of the cell. The chloroplast is thin at the margin. It is split into several lobes so closely appressed that the sinuses between the lobes are scarcely discernable. As seen in optical section, each lobe is thickened inwardly and is coarsely lamellated. No distinct pyrenoid is visible, but I hesitate to say none is present because of the lamellations. Starch is present (IKI test) but scattered and unrelated to the thickened areas. There are no pseudocilia present. When stained with methylene blue, the enclosing gel is seen to contain many bacteria, oriented in radiating lines. Although I did not observe asexual reproduction by zoospores, Flint (1974) has shown them to be unequally biflagellate. Evidence of zoospore production having taken place in my material is presumed since each of the plants was attached by a gelatinous disk a bit wider than the gel immediately above. The cells varied from hemispherical through broadly ellipsoidal to spherical. They measured 5-9 m in their narrowest diameter and 8-14 m in their largest diameter. Christiansen (1962) discovered in a peat digging in Denmark an alga which he initially determined as H. transversalis. On the basis of further study of this material, he transferred the species to Radiofilum transversale (de Brdb.) Christansen. Printz (1927) earlier had listed H. transversalis as a synonym of Radiofilum irregulare (Wille) Brunnthaler (1913), but did not cite this transfer in his later publication (Printz 1964). Christiansen gave a general morphological description and excellent photomicrographs of both his material and of the type herbarium material of the species H. transversalis. It is evident that Flint (1974) was not aware of Christiansen's (1962) paper as she did not cite his work. Based on Christiansen's general description and the type material of H. transversalis, I believe the Michigan alga to be the same
Page 107 ï~~2007 THE MICHIGAN BOTANIST 107 2007 THE MICHIGAN BOTANIST 107 FIGURES 1-6. Parallela novae-zealandiae. 1. Young plant with a uniseriate arrangement of cells enclosed by a continuous gel equal in thickness to the cell diameter. 2. Transition from uniseriate to biseriate filament through longitudinal divisions. 3. Additional longitudinal divisions produce a tiered arrangement of four cruciately arranged cells. 4. Apex of the plant where small groups of cells are scattered irregularly throughout. 5. Whole thallus clavate in shape. 6. Pleuriseriate filament. Scale bars: 1-4, 6 = 10 m; 5 = 10 cm.
Page 108 ï~~108 THE MICHIGAN BOTANIST Vol. 46 species. I further believe that it should not have been transferred to the genus Radiofilum. First: The morphology of the chloroplast as seen in the Michigan alga is quite different from the chloroplast morphology in Radiofilum. It almost completely lines the cell wall where that of Radiofilum scarcely covers two-thirds. Second: An obvious, distinctive pyrenoid is not discernable in the Michigan specimens. Radiofilum usually has one, sometimes two, clearly visible pyrenoids. Third: The growth pattern of Christiansen's material and of the Michigan material is clearly not that of a Radiofilum, but identical to Parallela. While Radiofilum is known to develop a palmelloid phase, it is an unorganized dispersion of cells in a common gel, contributed by each cell. It is never the regular, sometimes synchronous and parenchymoid (sarcinoid) development that is produced in H. transversalis as it grows in cellularity. Fourth: The formation of false branches in H. transversalis is a dissociation phenomenon, as Christiansen described it, and not a positive growth action as in true branching or in link formation in Radiofilum. When R. conjuctivum Schmidle does branch, it is a true branching with continued cellular contact along the main filament as well as with the branch and not a mere breaking and turning a side of a portion of the main filament as in false branching. The distribution of Parallela appears to be wide spread, but this supports previous finds that the geographical distribution of freshwater algal species is much wider than that of most marine species (Round 1981). No major group of genera seems to be confined to any one geographical area as is the case with marine forms. Lists of species from many parts of the world tend to contain large number of cosmopolitan species; some "reliable lists give between 50 and 70% as cosmopolitan" (Round 1981). Although a heterogeneous assemblage, the green algal order Tetrasporales has immobile vegetative cells that are capable of cell division, unlike those in the orders Chlorococcales and Volvocales. The colonies are never truly filamentous. Several of the Tetrasporales are so closely allied to the Volvocales (Volvox and related genera) that their cells have many characteristics of the volvocaceous cell. Recent RNA sequences have confirmed this phylogenetic position (Nozaki et al. 2003; Nakazawa 2004). Until molecular data on P nova-zealandiae are obtained, it is best retained within the order Tetrasporales, family Palmellopsidaceae (Table 1) as proposed by Entwisle & Skinner (2001). One further collection from twigs in Lake Geneserath established the alga's presence in northern Michigan. Both Stony Lake and the northern arm of Lake TABLE 1. Systematic placement of Parallela novae-zealandiae. Author Order Family Flint (1974) Tetrasporales Palmellaceae Santa Anna (1974) Chlorococcales None listed Komairek & Fott (1983) Chlorococcales Palmellaceae Entwisle (1989) Tetrasporales Tetrasporaceae Entwisle & Skinner (2001) Tetrasporales Palmellopsidaceae
Page 109 ï~~2007 THE MICHIGAN BOTANIST 109 Geneserath are nutrient enriched habitats, similar to the site of the organism's original New Zealand collection. ACKNOWLEDGEMENTS I thank Dr. James Gillingham, Director of Central Michigan University's Biological Station, Beaver Island, for providing laboratory space, the late Dr. R.H. Thompson for drawing my attention to Flint's paper, and Drs. M.J. Wynne and P.C. Silva for additional literature assistance. Brian Roberts assisted in the preparation of the plates. LITERATURE CITED Bold, H.C. (1967). A Laboratory Manual for Plant Morphology. Harper & Rowe, New York. 123 pp. Brunnthaler, J. (1913). Die Algengattung Radiofilum Schmidle und ihre systematische Stellung. Osterreichische Botanische Zeitschrift 63: 1-8. Christensen, T. (1962). Palmella formation in Radiofilum transverale (Br6b.) comb. nov. Flora 152: 74-80. de Br6bisson, A. (1839). De quelques nouveaux genres d'algues. M6moires Societe Academiquedes Falaise 3: 34-37. de Br6bisson, A. (1844). Description de deux nouveaux genres d'algues fluviatiles. Annales des Sciences Naturelles, s6ries Botanique 1: 25-31. Entwisle, T.J. (1989). Macroalgae in the Yarra River Basin: flora and distribution. Proceedings of the Royal Society of Victoria 101: 1-76. Entwisle, T.J. & S. Skinner. (2001). Non-marine algae of Australia: 4. Floristic survey of some colonial green macroalgae (Chlorophyta). Telopea 9: 725-739. Flint, E.A. (1974). Parallela, a new genus of freshwater Chlorophyta in New Zealand. New Zealand Journal of Botany 12: 357-364. Komarek, J. & B. Fott. (1983). Chlorophyceae (Grinalgen), Ordnung Chlorococcales. In: Das Phytoplankton des Si, wassers (H.-J. Elster & W. Ohne, eds.), Teil 7, Hailfte 1. E. Schweizebart'sche Verlangsbuchhandlung, Stuttgart, 1044 pp. Nakazawa, A. (2004). Phylogenetic analysis of the tetrasporalean genus Asterococcus (Chlorophyceae) based on 18S ribosomal RNA gene sequences. Journal of Japanese Botany 79: 255-261. Nozaki, H., O. Misumi & T. Kuroiwa. (2003). Phylogeny of the quadriflagellate Volvocales (Chlorophyceae) based on chloroplast multigene sequences. Molecular Phylogenetics and Evolution 29: 58-66. Prescott, G.W. (1962). Algae of the Western Great Lakes Area. W.B. Brown, Dubuque, IA. 977 pp. Printz, H. (1927). Chlorophyceae. In: Engler and Prantl, Die NarUirlichen Pflanzenfamilien, 2 Aufl., Bd. 3. Printz, H. (1964). Die Chaetophoralean der Binnengewisser. Hydrobiologia 24: 1-376. Reinke, D.C. (1983). Algae collected by Rufus H. Thompson, II. Parallela nova-zealandiae, first report from North America. Technical Publications of the State Biological Survey of Kansas 13: 22-23. Round, F.E. (1981). The Ecology of Algae. Cambridge University Press, NY. 653 pp. Santa Anna, C.L., R.M.T. Bicudo & C.E.D.M. Bicudo. (1979). The record of Parallela (Chlorococcales, Chlorophyceae) in Brazil. Rickia 8: 101-104. Taylor, M. (1975). Comments on Parallela (Chlorophyta). New Zealand Journal of Botany 13: 323-324. Wehr, J.D. & R.G. Sheath. (2003). Freshwater Algae of North America. Academic Press, NY. 918 pp.