New Zealand Loses Another Endemic Fern Genus
Kreier & Schneider (2006) largely based on a sampling of four chloroplast genome regions (rbcL, rps4, rps4-trnS IGS and trnL-F IGS) have just reinstated Loxogramme dictyopteris (Mett.) Copel as the most appropriate name for the Polypodiaceous fern long known in New Zealand as Anarthropteris lanceolata (J.Sm. ex Hook.f.). Based on their findings from their inferred molecular phylogeny the authors argue that because Anarthropteris Copel. is firmly nested within Loxogramme (Blume) C.Presl, and that this placement does not conflict with the existing morphological distinctions of that genus, the name L. dictyopteris should be revived. In particular they note that both genera share undivided frond laminae, lack internal sclerenchyma (except within the roots), and frequently possess receptacular appendages. From Loxogramme, Anarthropteris had been separated because of its more or less round sori and unique receptacle scales. However, the authors point out that sorus shape and position is rather variable in Loxogramme, and that “filiform” receptacular appendages, which are very similar to the scale-like appendages of Anarthropteris, occur in some species. So they conclude that as there are no significantly distinctive characters on which to base the generic separation, and that the alternative based on their molecular evidence would necessitate the unwarranted splitting of an otherwise morphologically cohesive Loxogramme, the best course of action is to synonymise Anarthropteris within it.This move now leaves New Zealand with 64 endemic genera (cf. de Lange et al. 2006), two of which are the fern genera Leptolepia Prantl and Loxsoma R.Br. ex A.Cunn. Of these two fern genera, Leptolepia seems unlikely to stand the test of time with research in progress casting considerable doubt on its status, while Loxsoma – at least on present evidence - seems unassailable.
References
de Lange, P.J.; Sawyer, J.W.D.; Rolfe, J.R. 2006: New Zealand Indigenous Vascular Plant Checklist. Wellington, New Zealand Plant Conservation Network. 94pp.
Kreier, H-P.; Schneider, H. 2006: Reinstatement of Loxogramme dictyopteris, based on phylogenetic evidence, for the New Zealand endemic fern, Anarthropteris lanceolata (Polypodiaceae, Polypodiidae). Australian Systematic Botany 19: 309-314.
Posted: 06/11/2006