OOSPORE VARIATION IN CLOSELY RELATED CHARA TAXA¹

Abstract

Charophytes produce a thick-walled zygote, the so-called oospore, the characters of which (size, shape, and structure) are used as taxonomic determination criteria. In the present study, the variation of length, width, length-to-width ratio, and number of striae of oospores collected both from the field and after cross-fertilization experiments was compared within and among taxa, populations, and individuals belonging to the Chara baltica Bruzelius "species complex." Although the oospore characteristics differed significantly among the taxa, the variations among populations belonging to the same taxon and even among individuals belonging to the same population were still higher. Oospores developed by means of allogamy were not significantly different from oospores developed by autogamy. Oospores were 5% shorter and 27% narrower when measured dry compared with wet material. Information about this treatment is unfortunately lacking in charophyte monographs and oospore determination keys. We concluded that oospore descriptions of different charophyte taxa should be based on a larger amount of data material collected from different populations and individuals and accompanied by a detailed method description, and that a determination of closely related taxa by means of oospores should be interpreted carefully. Ecological aspects of oospore size variation are discussed.

DNA barcoding the genus Chara: molecular evidence recovers fewer taxa than the classical morphological approach

“…Indeed, taxa included in cluster I cannot be differentiated by oospore traits (Blume et al. ), while other species are different (Holzhausen et al. ), thus supporting the results summarized in Figure .…”

Taxonomical analysis of closely related species of Chara L. section Hartmania (Streptophyta: Charales) based on morphological and molecular data

“…Such results can also be helpful in explaining the phylogenetic relationships between species (Sakayama et al 2002(Sakayama et al , 2004(Sakayama et al , 2005Urbaniak 2010). The large amount of data collected during this study seems to confirm the considerable variety in oospore size among populations of the same species, as has been reported previously (caSanova 1997;bLUme et al 2009;Urbaniak 2010;Urbaniak & combik 2017).…”

“…In order to allow for the morphological analysis of oospore differences (length, width, number of striae and fossa width) between taxa and single populations, min-max (haaS 1994;veddeR 2004;bLUme et al 2009), however, only little is known about the influence of oospore cleaning (acetolysis) procedures on these features. This was checked in an additional study which evaluated the entire preparation procedure with chemical treatment during cleaning and showed how this procedure influenced oospores.…”

“…4-8). This indicates that C. baltica can be clearly distinguished from the other four species (C. hispida, C. polyacantha, C. rudis and C. intermedia) based on oospore wall ornamentation (mannSchreck et al 2002;bLUme et al 2009;boegLe et al 2010). C. baltica is a truly brackish water species and occurs in the enclosed area of the Baltic Sea, with some disjunctive localities in Southern France (bLUemeL 2003).…”

Caracteres estructurales y ultraestructurales de la gametogénesis de Chara hydropitys (Charophyceae)

“…Ambos gametangios poseen células estériles conocidas como células escuderas que los rodean y protegen (Pickett-Heaps, 1968;John et al, 1990;Leitch et al, 1990;Graham et al, 2009;Lee, 2008;Sakayama, 2008;Sato et al, 2014). A pesar de que la microarquitectura de la pared externa de la oosfera reviste gran importancia taxonó-mica, sistemática y evolutiva, son escasos los trabajos encontrados en la literatura científica encaminados a describir la variabilidad de estos patrones Leitch et al, 1990;Casanova, 1991Casanova, , 1997Ray et al, 2001;Blume, Blindow, Dahlke, & Vedder, 2009;Urbaniak, 2011, Schneider et al, 2015. Algunos autores también han indicado que la microestructura interna de la pared oosporangial compuesta (POC) podría aportar datos importantes para el entendimiento de la biología reproductiva y sistemática de las Charophyceae en general (Leitch, 1986(Leitch, ,1989John & Moore, 1987;Leitch, 1989;Leitch et al, 1990;Sakayama et al, 2005).…”