Spirogyra salmonispora sp. nov. (Zygnematophyceae, Chiorophyta), a New Freshwater Species of the Section Conjugata

Arch. Protistenkd. 146 (1995): 101-106

ARCH IV

© by Gustav Fischer Verlag Jena

FUR

PROTISTEN KUNDE

Spirogyra salmonispora sp. nov. (Zygnematophyceae, Chlorophyta), a New Freshwater Species of the Section Conjugata N.

C. FERRER

& E. J.

CACERES

Departamento de Biologfa, Universidad Nacional de Sur, Bahia Blanca, Argentina Summary: Details of the morphology and life history of Spirogyra salmonispora sp. nov. from the south of the province of Buenos Aires, Argentina, are described. This species has scalariform conjugation and produces two morphologically different types of zygospores. The mesospore is salmon-colored with a fine and irregularly reticulate surface. Key Words: Spirogyra salmonispora sp. nov.; Diagnosis; Life cycle; Morphology.

Introduction The section Conjugata was created by HANSGIRG in 1886 (see KADLUBOWSKA 1984) by segregating the species of Spirogyra with plane end walls and cells not joined by means of rings. KADLUBOWSKA (1984) divided the section into four groups: Longata, Nitida, Punctata and Maxima, based on zygospore characteristics and the number of chloroplasts per cell. The present work describes in detail the morphology and biology of Spirogyra salmonispora sp. nov., a new member of the section Conjugata, group Maxima. To date, 293 species have been described for this section throughout the world (KADLUBOWSKA 1984).

Material and Methods The study was carried out on natural popUlations growing in an artificial shallow lake situated in Parque de Mayo, Bahia Blanca, Province of Buenos Aires, Argentina (38° 41'S, 62° 15'W). The lake receives water from the Naposta Creek and covers approximately 3 hectares. The cli-

mate can be described as arid temperate (Zonobiome VII) according to the climate classification of WALTER et al. (1975), with mean air temperatures ranging from 4.3-15.9 °C in winter and 16.6---42.5 °C in summer (DONNARI & TORRE 1974). Observations were carried out during 1989-1991 on recently collected plants and those in culture. Strains of S. salmonispora are regularly maintained in Woods-Hole medium (SIMONS et al. 1984) at 20-21 °C under 12:12 h LD regime or 10-12 °C under 8:16 LD regime by illumination with 20 W cool-white fluorescent lamps providing 67 !lmol . m-2 • S-l. Clonal cultures were started from small pieces of recently collected filaments 3 to 5 cells long. Cultures were transferred regularly each 30 ± 10 days. The growth pattern of the species was defined by periodic observation of undisturbed young replicates. A holotype and paratypes of S. salmonispora have been deposited in the Laboratorio de Plantas Avasculares, Departamento de Biologia, Universidad Nacional del Sur, Bahia Blanca, Argentina and the Bahia Blanca Biologia Herbarium (BBB). Preparation of zygospores for scanning electron microscopy (SEM) was performed using the methods described by HULL et al. (1985). Removal of the exospore was carried out mechanically.

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N. c.

FERRER

& E. 1. CACERES

Spirogyra saimonispora sp. nov.

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Results

Description of the new species

Spirogyra salmonispora sp. nov.

Vegetative cells 66.3-93.6 /lm in diameter (x =78.84, S =5.02, n = 67); 187.2-468 /lm long (x =279.52, S = 71.32, n = 67), with plane end walls; (4) 5 (6) chloroplasts with midrib and irregularly spaced pyrenoids (5-15 /lm in diameter) making 1.5 to 3 turns in each cell. Conjugation scalariform, tubes well developed and formed by both gametangia; fertile cells cylindric. Zygospores ellipsoid or cylindric with rounded ends, 81-92 x 101-188 /lm, exospore smooth and colorless, mesospore thick and salmon-colored, fine and irregularly reticulate. Interphasic nucleus square in optical

Latin Diagnosis Cellulis vegetativis 66.3-93.6 /lm latis, 187.2-468 /lm longis; dissepimentis planis; chromatophoris (4) 5 (6), anfractibus 1.5 ad 3, pyrenoideis irregulariter dispositis; conjugatione scalari; cellulis fructiferis cylindricis; zygosporis ellipsoideis vel cylindricis apice rotundatis, 81-92 x 101-188 /lm, mesosporio crasso, salmoneo, subtiliter et irregulariter reticulato.

Table 1. Comparison between S. salmonispora sp. nov. and S. malmeana HIRN. Characteristics of S. malmeana as given by KOLKWITZ & KruEGER (1944a), TRANSEAU (195P), RANDHAWA (1959c), GAUTHIER-LIEVRE (1965 d) and KADLUBOWSKA (1972e ;

1984~

S. salmonispora

S. malmeana

Vegetative Cells Diameter (in /lm)

66.3-93.6

76_91 a,b,c,e 83-90d 76-99 f

Length (in )lm)

187.2-468

160-300b

Chloroplasts

4-6 with midrib

3-4a, b, c, e, f

4d

Conjugation tubes

formed for both gametangia and well developed

formed for both gametangia and little developeda- f

ellipsoid and cylindric with rounded ends

ellipsoida- f

Zygospores Shape

Dimensions (in )lm)

81-92 x 101-188

52-65 x 74--98 a,e,f 65-83 x 75-100b,c 55-60 X 85-95 d

Position in the gametangia

parallel to the long axis of the cell

at an angle of 45° with the long axis of the cella- f

Mesospore color

salmon-colored

yellow-brown a- f

Mesospore ornamentation

irregularly reticulate

irregularly reticulatea- f

Figs. 1-10. Spirogyra salmonispora. Fig. 1. Vegetative filament. Fig. 2. Detail of a vegetative cell. Figs. 3-6. Conjugating filaments. Figs. 3 and 5 show successive stages of the formation of the conjugation tubes. Figs. 7, 9. Zygospores in lateral view. Figs. 8,10. Gametangia with mature zygospores. Scale bar in Fig. 1 = 100 )lm, also for Figs. 4,8 and 10 and 10 )lm in Fig. 2, also for the rest of the figures.

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N. C. FERRER & E. J. CACERES

Figs. 11-15. Spirogyra salmonispora. Figs. 11, 12. Light microscope. Fig. 11. Zygospores in lateral view. Fig. 12. Mesospore ornamentation. Figs. 13-15. SEM. Fig. 13. Zygospore in lateral view. Fig. 14. Zygospore in apical view. Fig. 15. Mesospore ornamentation. Scale bars = 10 /lm except for Fig. 15 = 1 /lm.

section, 20 x 20 /lm, with one nucleolus, 9-10 /lm in diameter. In the natural environment filaments of S. salmonispora appeared bright green and normally aggregated in very long masses, floating on the water surface and growing down to 30 cm deep. Conjugation took place during October-November with water temperatures up to 31°C and pH 7.5. In culture, filaments grew straight and tended to remain horizontal, loose and parallel to each other, thus forming initially ring-shaped and later disc-shaped masses. The diameters of the filaments were normally smaller than those in nature and the number of chloroplasts was observed to vary between 4 and 6. Conjugation could not been induced in culture.

Discussion With the sole exception of the work of SECKT (1929), the family Zygnemataceae has received little attention in phycological studies of Argentina. Although many species have been mentioned in different works (GUARRERA & KOHNEMANN 1949; TELL 1985), most of the knowledge we have on Argentine Zygnemataceae comes from studies in which they have been treated incidentally, with no precise details on their taxonomical state, morphology, biology or geographical distribution. TELL (1985) mentioned 28 species of the Conjugata section for Argentina, 4 of them belonging to the Maxima group.

Spirogyra salmonispora sp. nov.

For the description of this new species we have taken mainly into account the traits and characteristics used by KADLUBOWSKA (1983) in the treatment of the Zygnemataceae. We have emphasized the observation of the zygospore attributes in view of the dwindling relevance of other morphological traits such as filament diameter, wich is highly influenced by the level of ploidy (HOSHAW & HULL 1981; HOSHAW et al. 1985, 1987). The taxonomic significance of zygospore ornamentation as viewed with SEM has already been stressed in several works on Spirogyra and Sirogonium (HOSHAW 1980; ASHRAF & GODWARD 1980; SIMONS et al. 1982; DE VRIES et al. 1983; HULL et al. 1985). Since S. salmonispora shares with other species of the Maxima group (i.e. S. malmeana, S. anomala, S. brunnea) the reticulate ornamentation of the mesospore, we assume these three species to be the most related to the proposed new species, though no exhaustive comparisons can be made owing to the lack of SEM studies on these three species. Table 1 shows a comparison between S. salmonispora and S. malmeana, presumably the nearest relative with reticulate mesospore. S. salmonispora resembles S. malmeana in cell diameter and mesospore ornamentation, yet differs with respect to zygospore dimensions, color and position in the gametangia, the development of the conjugation tubes and the number and characteristics of the chloroplasts. Acknowledgements: This research was conducted in partial fulfilment of the requirements for the Ph.D. degree of N.F. in the Universidad Nacional del Sur, and was supported by the Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina, grant PID 3-110-500/88. N.F. was the recipient of a fellowship from the Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina and E. 1. C. is a research member of the Comision de Investigaciones Cientfficas de la Provincia de Buenos Aires, Argentina. Special thanks are given to the late Dr. ROBERT W. HOSHAW of the University of Arizona, U.S.A. and to Dr. JOANNA Z. KADLUBOWSKA of the University of Lodz, Poland, for their competent opinions with respect to the creation of this new species and for their helpful comments on the manuscript.

References ASHRAF, M. & GODWARD, M. B. E. (1980): Ultrastructure and chemistry of the zygospore wall of Spirogyra. Ann. Bot. 46: 485-487. DE VRIES, P. J. R.. SIMONS, 1. & VAN BEEM, A. P. (1983): Sporopollenin in the spore wall of Spirogyra. Acta Bot. Neerl. 32: 25-28. DONNARI, M. A. & TORRE, L. E. (1974): AmHisis de algunos aspectos del clima de Bahia Blanca. Bahia Blanca.

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GAUTHIER-LIEVRE, L. (1965): Zygnemacees Africaines. Weinheim. GUARRERA, S. A. & KUHNEMANN, O. (1949): Catalogo de las "Chlorophyta" y "Cyanophyta" de agua dulce de la Republica Argentina. Lilloa 19: 219-318. HOSHAW, R. W. (1980): Systematics of the Zygnemataceae. II. Zygospore wall structure in Sirogonium and a taxonomic proposal. J. Phycol. 16: 242-250. - & HULL, H. M (1981): Ploidy and speciation in the Zygnemataceae. 1. Arizona-Nevada Acad. Sci. Proc., Suppl. 16: 20-21. - WANG, J. c., Mc COURT, R. M. & HULL, H. M. (1985): Ploidal changes in clonal cultures of Spirogyra communis and implications for species definition. Am. 1. Bot. 72: 1005-10 11. - WELLS, C. V. & Mc COURT, R. M. (1987): A polyploid species complex in Spirogyra maxima (Chlorophyta, Zygnemataceae), a species with large chromosomes. J. Phycol. 23: 267-273. HULL, H. M., HOSHAW, R. W. & WANG, 1. C. (1985): Interpretation of zygospore wall structure and taxonomy of Spirogyra and Sirogonium (Zygnemataceae, Chlorophyta). Phycologia 24: 231-239. KADLUBOWSKA,1. Z. (1972): Chlorophyta V. Conjugales. Zygnemaceae. In: K. STARMACH & 1. SIEMINSKA (eds.), Flora Slodkowodna Polski, Vol. 12A, pp. 1-431. Krak6w. - (1983): On changes in the nomenclature of some taxa of Zygnemataceae. Acta Soc. Bot. Poloniae 52 (3-4): 315-320. - (1984): Conjugatophyceae I. Chlorophyta VIII. Zygnemales. In: H. ETTL, J. GERLOFF, H. HEYNIG & D. MOLLENHAUER (eds.), StiBwasserflora von Mitteleuropa, Bd. 16, pp. 1-532. Stuttgart, New York. KOLKWITZ, R. & KRIEGER, H. (1944): Zygnemales. In: R. KOLKWITZ (ed.), L. Rabenhorst's Kryptogamen-Flora von Deutschland und der Schweiz, Bd. 13, pp. 1-499. Leipzig. RANDHAWA, M. S. (1959): Zygnemaceae. New Delhi. SECKT, H. (1929): Estudios hidrobio16gicos en la Argentina. Conjugatae. Bol. Acad. Nac. Cs. Cordoba 31: 19-7l. SIMONS, J., VAN BEEM, A. P. & DE VRIES, P. J. R. (1982): Structure and chemical composition of the spore wall in Spirogyra. Acta Bot. Neerl. 31: 359-370. - (1984): Induction of conjugation and spore formation in species of Spirogyra (Chlorophyceae, Zygnemataceae). Acta Bot. Neerl. 33(3): 323-334. TELL, G. (1985): Catillogo de las algas de agua dulce de la Republica Argentina. Vaduz. TRANSEAU, E. N. (1951): The Zygnemataceae. Columbus. WALTER, H., HARNICKELL, E. & MOLLER-DoMBOIS, D. (1975): Climate diagram maps of the individual continents and the ecological climatic of the Earth. Berlin, Heidelberg and New York. Accepted: January 11, 1995 Authors' address: N. C. FERRER & E. 1. CACERES, Universidad Nacional del Sur, Departamento de Biologia, San Juan 670, 8000 Bahia Blanca, Argentina.