When morphology and molecules tell us different stories: a case-in-point withLeptodon corsicus,a new and unique endemic moss species from Corsica

Abstract

Leptodon corsicus (Neckeraceae) is described as the first endemic moss species from Corsica. It strikingly differs from the other species of the genus by the lack of a dense and pinnate to bipinnate mode of branching; about 10 times smaller shoots that do not inroll upon drying; the lack of paraphyllia; and few, occasional small pseudoparaphyllia. Due to its small size and several leaf characters, L. corsicus shares at first glance more similarities with Homalia webbiana and Neckera besseri than with Leptodon. Yet, phylogenetic analysis of chloroplast and nuclear DNA sequences unambiguously shows that L. corsicus is deeply nested within L. smithii. The numerous morphological characters that distinguish L. corsicus from L. smithii cannot be attributed to plasticity. Consequently, we interpret the phylogenetic position of L. corsicus as the result of a recent speciation process, involving mutations at one or a few coding loci or differences in gene expression, which have tremendous consequences for phenotypic appearance, and retention of ancestral polymorphism in the non-coding sequences used for phylogenetic reconstruction. Such an explanation might also apply to other species of mosses, which exhibit a striking morphology, and yet share identical non-coding sequences with the common species they derive from. The notion of species in mosses is discussed in this context.

20,000 species and five key markers: The status of molecular bryophyte phylogenetics

“…However, Kelchner (2002) reported mutational heterogeneity, especially with respect to microstructural mutations. This has been further exemplified by Sotiaux et al (2009) who showed that the presence or absence of a 20 nt simple sequence repeat (SSR) can be of independent origin, even at species level. This example, however, also illustrates the potential of the region and its current application.…”

“…The full length region from trnS to trnF, in contrast, has been applied only recently (e.g. Hernández-Maqueda et al 2008a,b;Olsson et al 2009a,b;Sotiaux et al 2009). The following presents the different markers of the trnS-F region based on typical amplification strategies.…”

The application of molecular data to the phylogenetic delimitation of species in bryophytes: A note of caution

“…Such an explanation might also apply to other species of mosses that exhibit striking morphological difference, and yet share identical noncoding sequences with the common species they derive from (e.g., Platyhypnidium mutatum Ochyra & Vanderp. ; Stech & Frahm 1999; P. torrenticola (Ochyra, C. Schmidt & Bültmann) Ochyra & BednarekOchyra; Werner et al 2007; Thamnobryum angustifolium Nieuwland; Olsson et al 2009; Leptodon corsicus Enroth et al; Sotiaux et al 2009). As emphasised by Hedenäs & Eldenäs (2008), we still know little about molecular mechanisms of morphogenesis in mosses.…”

Biogeography of the Lost World (Pantepui region, northeastern South America): Insights from bryophytes

“…In the Canary Islands, the 1.5% of bryophyte species endemism pales in comparison with the 40% endemism rates observed in angiosperms (Vanderpoorten et al 2010b). In the western Mediterranean, Corsica and Sardinia, which harbour nearly 10% species endemism in angiosperms, a single endemic bryophyte species has been described (Sotiaux et al 2009). Even in Hawaii, one of the world's richest hot-spots of endemism, 29.4% and 48.6% of the moss and liverwort species, respectively, are considered endemic to the archipelago (Staples et al 2004;Staples & Imada 2006) and, since the liverwort flora of Hawaii has not been studied taxonomically, rate of endemism are probably much lower than indicated.…”