Morphometric analysis ofBatrachospermumsectionBatrachospermum(Batrachospermales, Rhodophyta) type specimens

Abstract

Type and historically important specimens of 46 species and infraspecific taxa from Batrachospermum sect. Batrachospermum were examined. Of these, 48 specimens of 33 taxa were compared using multivariate morphometrics and image analysis. Nine species from the cluster analysis and one other species are recognised: B. anatinum, B. arcuatum, B. boryanum, B. carpocontorum, B. confusum, B. fluitans, B. gelatinosum, B. heterocorticum, B. pulchrum and B. skujae. B. ectocarpum is considered to be synonymous with B. anatinum, rather than with B. boryanum or B. arcuatum as has been proposed by previous authors. The illegitimately named species B. helminthosum Sirodot (non Bory) is referable to B. confusum as are B. crouanianum and B. fruticulosum. No varieties of B. gelatinosum could be supported and numerous taxa including B. pyramidale, B. densum and B. decaisneanum are synonymised within this species. The taxa in sect. Batrachospermum are separated on the basis of whether they are monoecious or dioecious, carpogonium size, and the presence or absence of (I) spermatangia on the involucral filaments, (2) irregular cortication, (3) monosporangia, (4) well-curled fascicles and (5) secondary fascicles. Other qualitative characteristics previously used to separate taxa in this section, such as carposporophyte position, hourglass-shaped cells of the carposporophyte-bearing branch and brown cortication, were found to be too variable for use as taxonomic criteria. Additionally, the quantitative characteristics overlapped among specimens and were only useful in distinguishing B. fluitans from B. anatinum. Revised descriptions and a synoptic key of the species are provided.

Distribution and systematics ofBatrachospermum(Batrachospermales, Rhodophyta) in North America. 8a. SectionBatrachospermum:Batrachospermum gelatinosum

“…One distinguishing characteristic of B. gelatinosum is monoecious plants (Vis et al, 1995). The populations described by Necchi (1990) have dioecious thalli and those of Kumano (1979) are polyoecious, so that these populations cannot be referred to B. gelatinosum as circumscribed by Vis et al (1995). Geographic trends in morphological characteristics of B. gelatinosum populations were not evident among individual locations.…”

“…In comparison with the type specimen, the North American populations are similar in qualitative features, i.e. monoecious thalli and main axis with cylindrical cortical cells, and the ranges in morphometric characteristics overlap (Vis et al, 1995). Of the previous studies reporting measurements for at least a few features, the ranges in morphometric characteristics for the North American populations of this species are similar to those given for populations in Brazil (Necchi, 1990) Japan (Mort, 1975, Japan and Malaysia (Kumano, 1979) and Sweden (Israelson, 1942).…”

“…However, Necchi (1990) gives a greater maximum carpogonium length than that observed in the North American populations (75 vs 55 btm, respectively). One distinguishing characteristic of B. gelatinosum is monoecious plants (Vis et al, 1995). The populations described by Necchi (1990) have dioecious thalli and those of Kumano (1979) are polyoecious, so that these populations cannot be referred to B. gelatinosum as circumscribed by Vis et al (1995).…”

“…Batrachospermum (~-Moniliformia Sirodot, 1873) of the freshwater red algal genus Batrachospermum is generally characterized by the following features: welldeveloped whorls, undifferentiated and straight carpogonial branches arising from both fascicle and pericentral cells, non-pedicellate carpogonia with club-to urn-shaped trichogynes and relatively small globose, pedicellate carposporophytes at various distances from the whorl axis (Mori, 1975;Starmach, 1977;Kumano, 1993). The type species of the genus, B. gelatinosum (L.) deCandolle (= B. moni[iforme Roth), is contained within this section and is differentiated from other species of the section on the basis of monoecious thalli and cylindrical cortical cells covering the main axis (Vis et al, 1995).…”

Leveilleites hartnageli Foerste, 1923 (Rhodophyta?) from the Ordovician of Laurentia and Silurian of Baltica: Redescription and designation of a neotype

“…Similarities can be seen in their uniaxial branched body and position of reproductive structures (Vis et al, 1995).…”