Diphasiastrum oellgaardii (Lycopodiaceae, Pteridophyta), a new lycopod species from Central Europe and France

Abstract

A Diphasiastrum taxon being morphologically intermediate between D. alpinum and D. tristachyum is described as D. oellgaardii. During gel isoenzyme analyses, glucose‐6‐phosphate isomerase and esterase turned out to be electrophoretic markers testifying the hybrid origin of D. oellgaardii. In Europe, where three parental species (D. alpinum, D. complanatum and D. tristachym) occur, D. oellgaardii is the third taxon of hybrid origin besides D. issleri and D. zeilleri. Problems of reproductive biology of these taxa are discussed.

Resolving maternal relationships in the clubmoss genus Diphasiastrum (Lycopodiaceae)

“…Polyploids have been reported, but are considered rare (Wilce, 1965;Wagner, 1992). The few chromosome counts obtained from putative hybrid specimens would support a homoploid origin, as they show the expected diploid chromosome number 2n ≈ 46 (Wagner, 1992;Stoor & al., 1996).…”

“…American D. issleri is hypothesized to have the same parents as European D. oellgaardii (Wilce, 1965;Stoor & al., 1996). The two remaining species, D. sabinifolium (Willd.)…”

“…From then onwards, homoploid hybridization has been almost universally accepted as an important mechanism of species formation in Diphasiastrum. Yet what exists of molecular evidence for their hybrid origin (Stoor & al., 1996) has been shown to be inconclusive (Vogel & Rumsey, 1999).…”

“…These are necessary initial steps in order to further investigate reticulate events and putative homoploid hybrid speciation in Diphasiastrum. Two of the European hybrid taxa, D. oellgaardii and D. issleri, were represented by accessions from their type localities in the Vosges mountains (France), Champ du Feu and Le Tanet (Lawalrée, 1957;Stoor & al., 1996). The third hybrid species described from Europe, D. zeilleri, was represented by an accession from a well-known locality in northern Austria; Zwieselberg, Oberösterreich (Horn & Bennert, 2002).…”

“…Some species are described from tropical highlands with temperate climate, and a number of endemics have also been described from islands in both the Atlantic and the Pacific Ocean (Wilce, 1961(Wilce, , 1965. A unique feature, contributing to the species count in Diphasiastrum, is that at least five diploid hybrid species are commonly recognized in the genus (Wilce, 1965;Holub, 1975;Stoor & al., 1996). These have been reported as results of independent crosses involving different combinations of five putative parent species (Fig.…”