Scandinavian Oncophorus (Bryopsida, Oncophoraceae): species, cryptic species, and intraspecific variation

Lars Hedenäs

doi:10.5852/ejt.2017.315

Abstract

Scandinavian members of the acrocarpous moss genus Oncophorus were revised after field observations had suggested unrecognized diversity. Based on molecular (nuclear: internal transcribed spacers 1 and 2, ITS; plastid: trnGUCC G2 intron, trnG, rps4 gene + trnS-rps4 spacer, rps4) and morphological evidence, four morphologically distinguishable species are recognized, Oncophorus elongatus (I.Hagen) Hedenäs, O. integerrimus Hedenäs sp. nov. (syn. O. virens var. elongatus Limpr.), O. virens (Hedw.) Brid., and O. wahlenbergii Brid. (O. sardous Herzog, syn. nov.). Oncophorus elongatus was earlier recognized, but much of its variation was hidden within O. wahlenbergii. Its circumscription is here expanded to include plants with long leaves having mostly denticulate or sharply denticulate upper margins and with long and narrow marginal cells in the basal portion of the sheathing leaf lamina. The new species O. integerrimus sp. nov. differs from O. virens in having more loosely incurved leaves and entire or almost entire upper leaf margins. Besides these characters, the species in the respective pairs differ in quantitative features of the leaf lamina cells. Several cryptic entities were found, in several cases as molecularly distinct as some of the morphologically recognizable species, and phylogeographic structure is present within O. elongatus and O. virens.

Highlights

A significant proportion of species diversity is either not yet recognized, such as undescribed species, or hidden within morphologically closely similar or virtually identical species (Hawksworth 2001; Bickford et al 2006; Crawford & Stuessy 2016)
The morphological analysis was based on specimens of O. elongatus-O. wahlenbergii and O. virens s. lat. that were included in the molecular analysis, whereas the geographical distribution of the species that were recognized for Scandinavia was mapped based on all Scandinavian material present in the Swedish Museum of Natural History (S)
Neither in the internal transcribed spacers and 2 (ITS)- nor chloroplast-based analyses, O. crispifolius, O. dendrophilus, and O. rauei were found in positions that suggested that they are especially closely related to any of the Scandinavian species

Summary

Introduction

A significant proportion of species diversity is either not yet recognized, such as undescribed species, or hidden within morphologically closely similar or virtually identical species (Hawksworth 2001; Bickford et al 2006; Crawford & Stuessy 2016). Species of Oncophorus are frequent in many wet or humid habitats in arctic to temperate regions of the Northern Hemisphere, and in addition some species occur in Sri Lanka or temperate areas of the Southern Hemisphere (Frahm et al 1998; Frey & Stech 2009). Since additional species were distinguished or described (Hedenäs 2005; Hedderson & Blockeel 2006), and Frey & Stech (2009) recognized nine species in the genus. Some of the Scandinavian material considered by Frahm et al (1998) as belonging to O. wahlenbergii has later been recognized as a species of its own, O. elongatus (I.Hagen) Hedenäs, restricted mainly to the mountains and the far north (Hedenäs 2005). Hagen (1899) originally distinguished this taxon by its large, yellowgreen, incoherent tufts, leaves 5.3 mm long and 1 mm wide, and a long-excurrent leaf costa

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Conclusion