Page  149 ï~~2003 THE MICHIGAN BOTANIST 149 A NEW SPECIES OF CHAETONEMA (CHLOROPHYCEAE) Daniel E. Wujek Rufus H. Thompson1 Department of Biology Department of Botany Central Michigan University University of Kansas Mt. Pleasant, Michigan 48859 Lawrence, Kansas 66045 ABSTRACT A description of a new species of the green algal genus Chaetonema, C. minima, is presented. A key to the species of Chaetonema now recognized is given. INTRODUCTION Chaetonema Nowakowski (1877), a green alga placed in either the Chaetophoraceae (Smith 1950) or Aphanochaetaceae (Bourrelly 1966), grows epiphytically on other algae, especially those which produce large amounts of mucilage, e.g., Batrachospermum, Chaetophora, Tetraspora. It is because of the mucilage of its "host" that this genus is often overlooked. The thallus consists of irregularly twisted main branches which bear short lateral branches terminating in long hyaline unicellular setae. In addition to the type species, C. irregulare, one other species has been described, C. ornatum (Transeau 1943). In North America, C. ornatum has been observed from Alabama and Nova Scotia (Transeau 1943), while C. irregulare has been reported from the New England area (Collins 1918; Prescott & Croasdale 1942) and Michigan and Wisconsin (Prescott 1962). This paper reports the description of a new species of Chaetonema observed initially in several northern Minnesota locations, and subsequently observed from various Michigan sites. METHODS AND MATERIALS Samples containing Chaetonema minima were collected from the following sites: Michigan: Charlevoix County-Greene's Lake, July 1990-94, Montcalm County-Vestaburg Bog, June to July-sporadically 1970-95; and in Minnesota: Becker, Clearwater, and Hubbard County lakes and ponds in the Itasca State Park and adjoining waters, June-July 1960, 1964-1965 (waters described in Meyer & Brook 1968). Observations were made from both freshly collected material and from stock cultures grown in 1Deceased 3 June 1980. Dr. Thompson is included as an author as he first directed my attention to this organism in 1964 when he was teaching a freshwater algae course at the University of Minnesota's Biological Station and I was his teaching assistant and graduate student. He was the source for some of the descriptive data included in this paper. I 'rediscovered' the organism many years later in Michigan. He had never taken the time to formally describe the organism as new to science.

Page  150 ï~~150 THE MICHIGAN BOTANIST Vol. 42 150 THE MICHIGAN BOTANIST Vol. 42 FIGURES 1-6. Chaetonema minima. Fig. 1. Filaments (arrows) in mucilage of a Batrachospermum vagum thallus. Figs. 2-3. Oogonia at two different focal planes. Figs. 4-5. Oogonia. Fig. 6. Short filament and single cells on a Desmidium baileyi filament. Scale bars = 10 pm. soil water extract or Bold's Basal Medium (Bold 1967) supplemented with additional soil water extract. Material was abundant enough to permit the observation of a number of characters and something of its reproduction. Cultures no longer survive. RESULTS AND DISCUSSION Chaetonema minima Thompson et Wujek sp. nov. (Figs. 1-6) Diagnosis: Alga heterothallica, planta feminea 1-4 cellularum, planta mascula ramificans, usque ad 16 cellularum; amba, una pila unicellularis per cellulam, basi bulbositer intrusus. Omnis cellula plastida partiale continens uno ad pluribus pyrenoidibus fere obtectante parietis.

Page  151 ï~~2003 THE MICHIGAN BOTANIST 151 Cellula mascula plus minusve circum, 5.7-10 tm diametro. Cellula ultima plantae feminae novam plantam faciens 15.8-20 m diametro. Gametae masculae ob cellulas terminales productae, 4 per cellulam, quadriflagellatae usque ad 7 tm latae, 10 tm longae, chloroplasto cupulato pyrenoide et stigmata anteriolaterale continente in vesiculam relicto. Ovum in oogonio libere quiescens, puncto receptivo recte sub apertura circularis in pariete dishaerenti pila unicellulari. Ovum maturum confertim amylo impletum, 15-16 tm diametro; zygota crassiparietalis laevisque 17-19 tm diametro. Zoospora aut germination zygotae non vidi. Holotypus: Fig. 2. Locus typi: West Twin Lake, Itasca State Park, Clearwater County, Minnesota, USA, 28 June 1960. Alga heterothallic, the female plant 1-4-celled, the male plant branching and up to 16-celled. Both bear unicellular hairs, one per cell, which are bulbously implanted at the base. Each cell contains a partial plastid, which lines the cell wall almost completely and contains one to several pyrenoids. Cells of the male plant are more or less rounded and measure 5.7-10 m in diameter. Each ultimate cell of the female plant becomes an oogonium 15.8-20 tm in diameter. Male gametes are produced in the terminal cells, four per cell. They are quadriflagellate, up to 7 m wide by 10 tm long and contain a cup-shaped chloroplast with a pyrenoid and an anteriolateral stigma. They are released in a vesicle. The egg lies free in the oogonium and bears a clear receptive spot directly beneath the circular opening left in the wall by dehiscence of the unicellular hair. The mature egg is densely packed with starch, 15-16 tm in diameter. The zygote measures 17-19 tm in diameter and has a smooth thick wall. Zoospores and germination of the zygote not seen. Alga originally found inhabiting the intercellular spaces in filaments of Desmidium baileyi. Initially collected in Itasca State Park, Minnesota, June 1960 and 1964. Subsequent observations were also made from acidic habitats in Kansas and Michigan. A comparison of C. minima with the other two described species is found in Table 1. Key to the species of Chaetonema. 1. Vegetative cells round, 6-10 m in length.......................................C. minima 1. Vegetative cells longer than broad, generally greater than 10 m in length (up to 5 0 m )....................................................................................................... 2 2. Oogonium 20-25 tm long x 40-45 m wide.........................C. irregulare 2. Oogonium 18-22 tm long x 32-35 m.....................................C. ornatum

Page  152 ï~~152 THE MICHIGAN BOTANIST Vol. 42 TABLE 1. Comparison of the three recognized Chaetonema species. C. irregulare C. ornatum C. minima thallus (excluding up to 30 cells; not up to 19 cells; not differentiated by sex; setae) differentiated by sex differentiated by sex male: 1-16 cells, female 1-4 cells vegetative cell 8-50 m long; 2-12 m 15-30 m long; 5.7-10 m; cells more diameter; cells 7-10 m diameter; or less globose cylindrical-barrel shaped cells barrel shaped setae 1-6, slightly bulbous up to 22, slightly 1-4, bulbous at base at base bulbous at base antheridium 10-15 m diameter 18-22 m diameter 10-12 m diameter oogonium globose, 20-25 m x globose, 18-22 m globose, 15.9 x 20 m; 40-45 m diameter occasionally ovoid up egg 15-16 m to 28 m long; wall marked with oblong pits male gametes size unknown; 8/cell, size unknown; 7 x 10 m; 4/cell, biflagellate 32-128/cell, biflagellate released in a vesicle, biflagellate hetero/homothallic homothallic apparently homothallic heterothallic zoospores 8-10 m long x 5 m 11-15 m diameter; unknown wide, oval; quadriflagellate quadriflagellate ACKNOWLEDGMENTS DEW would like to thank G. Williams and D. Dworzecki for assistance with the illustrations, Dr. Charles Ebel for the Latin translation, and Dr. James Gillingham, Director of the CMU Biological Station, for providing laboratory space. LITERATURE CITED Bold, H. C. 1967. A Laboratory Manual for Plant Morphology. Harper and Row, NY. Bourrelly, P. 1966. Les algues d'eau douce. I. Algues vertes. N. Boub6e & Compagnie, Paris. Collins, F. S. 1918. The green algae of North America. Second Supplement. Tufts College Studies, Vol. IV, No. 7. Meyer, K. J. 1930. Uber den Befruchtungsvorgang bei Chaetonema irregulare Nowak. Archiv fuir Protistenkunde 72: 147-157. Meyer, R. L. & A. J. Brook. 1968. Freshwater algae from Itasca State Park, Minnesota. I. Introduction and Chlorophyta. Nova Hedwigia 16: 257-266. Nowakowski, L. 1877. Beitrag zur Kenntnis der Chytridiaceen. Beitraige zur Biologie der Pflanzen 2: 73-100. Prescott, G. W. 1962. Algae of the Western Great Lakes, Revised Edition. Wm. C. Brown, Dubuque. Prescott, G. W. & H. T. Croasdale. 1942. The algae of New England. II. Additions to the fresh-water algal flora of Massachusetts. American Midland Naturalist 27: 662-676. Smith, G. M. 1950. Freshwater Algae of the United States. McGraw-Hill Book Co., NY. Transeau, E. N. 1943. Two new Ulotrichales. Ohio Journal of Science 43: 212-213.