A generic revision of the Warnstorfia-Calliergon group

Abstract

The genera of the Warnstorfia-Calliergon group are revised taxonomically. The following genera are recognized: (1) Calliergon (Sull.) Kindb., with C. cordifolium (Hedw.) Kindb., C. giganteum (Schimp.) Kindb., C. megalophyllum Mik. and C. richardsonii (Mitt.) Kindb.; (2) Loeskypnum Paul, with L. badium (Hartm.) Paul in Europe and L. wickesii (Grout) Tuom. occurring outside Europe only; (3) Straminergon Hedenäs, gen. nov., with S. stramineum (Brid.) Hedenäs, comb. nov.; (4) Warnstorjia Loeske, with W. exannulata (B., S. & G.) Loeske, W. fluitans (Hedw.) Loeske, W. procera (Ren. & H. Arn.) Tuom., W. pseudostraminea (C. Müll.) Tuom. & T. Kop., W. sarmentosa (Wahlenb.) Hedenäs, comb. nov., W. trichophylla (Warnst.) Tuom. & T. Kop. and W. tundrae (H. Arn.) Loeske in northern Europe and W. luipichensis (Williams) Hedenäs, comb. nov., and W. pseudo-sarmentosa (Card. & Thér.) Tuom. & T. Kop. occurring outside Europe only. Type material of many other taxa was studied and their generic placement considered, but in many cases the material was too sparse for judging the exact relationships to other species. Calliergon. is defined by the probable synapomorphies ‘stem leaves broadly ovate or broadly rounded-triangular’, ‘plants large’ and ‘axillary hairs large, 2-8(-10)-celled’, Loeskypnum by ‘often golden brown or coppery brown colour’, ‘strongly incrassate cells throughout the gametophyte’, ‘early brownish or yellow-brown axillary hairs’, ‘weak and comparatively short nerve, also in the perichaetial leaves’ and ‘few and only slightly inflated and differentiated alar cells’, Straminergon by the autapomorphies ‘colour pale green, whitish green or yellow-green’, ‘axillary hairs sparse, weak, 1-2-celled’, ‘alar groups ovate or broadly ovate, along the basal leaf margin’ and ‘margin of the perichaetialleaves strongly and irregularly dentate above’ and Warnstorfia by the probable synapomorphies ‘stem leaves not decurrent’ and ‘red colours frequently present’ . Additional characteristic features of the genera are also given and the taxonomic position of Warnstorfia tundrae, which does not fit well into any of the genera is discussed. Finally, the taxonomie position of the Warnstorfia-Calliergon group is discussed and keys are given for the European species.