New Taxonomic Arrangement of Dicranella s.l. and Aongstroemia s.l. (Dicranidae, Bryophyta)

Abstract

The recent molecular phylogenetic study of the families Aongstroemiaceae and Dicranellaceae, which resolved the genera Aongstroemia and Dicranella as polyphyletic, indicated the need for changes in their circumscription and provided new morphological evidence to support the formal description of newly recognized lineages. Following up on these results, the present study adds another molecular marker, the highly informative trnK-psbA region, to a subset of previously analyzed taxa and presents molecular data from newly analyzed austral representatives of Dicranella and collections of Dicranella-like plants from North Asia. The molecular data are linked with morphological traits, particularly the leaf shape, tuber morphology, and capsule and peristome characters. Based on this multi-proxy evidence, we propose three new families (Dicranellopsidaceae, Rhizogemmaceae, and Ruficaulaceae) and six new genera (Bryopalisotia, Calcidicranella, Dicranellopsis, Protoaongstroemia, Rhizogemma, and Ruficaulis) to accommodate the described species according to the revealed phylogenetic affinities. Additionally, we amend the circumscriptions of the families Aongstroemiaceae and Dicranellaceae, as well as the genera Aongstroemia and Dicranella. In addition to the monotypic Protoaongstroemia that contains the newly described dicranelloid plant with a 2-3-layered distal leaf portion from Pacific Russia, P. sachalinensis, Dicranella thermalis is described for a D. heteromalla-like plant from the same region. Fourteen new combinations, including one new status change, are proposed.

Keywords: Haplolepidous mosses; biodiversity; morphological convergence; nad5 G1 intron; phylogenetics; polyphyly; trnK; trnS-trnF region.

Figure 1

Maximum likelihood tree, inferred from the concatenated data matrix from the chloroplast trnF–trnS and trnK–psbA and mitochondrial nad5 intron 2 sequence data (LTRKN dataset) of selected species of Dicranidae, focused on the genera Dicranella and Aongstroemia, rooted with Pseudoditrichum mirabile. Bootstrap support values higher than 60 inferred from ML analyses, without and with indel coding, and posterior probabilities higher than 0.7 inferred from BI, without and with indel coding, are shown above the branches; hyphens in place of support values denote lower support of the node, while a blank space indicates that the node is absent from the topology inferred from the particular analysis; maximally supported nodes are indicated by solid lines and asterisks. Newly studied terminals, as well as terminals for which at least one marker was obtained de novo, are printed in bold, and terminals for which the trnK–psbA sequence is available are underlined. For details, see Appendix A.

Figure 2

Sporophytes and peristome of Dicranella staphylina (from North Siberia, MW9117945, FDt107). (A) fragment of specimen with sporophytes, (B) wet opening capsule with dehiscent annulus, (C–E) dry capsules, (F) SEM image of peristome, (G) outer surface of the lower part of segment, (H) spore. Scale bars: 1 mm for (A); 0.5 mm for (B–E); 100 μm for (F); 10 μm for (G); 2 μm for (H).

Figure 3

Line drawings of gametophyte and sporophyte of Siberian plants of Rhizogemma staphylina (from Russia: Krasnoyarsk Territory, Putorana Plateau, MW9117945, isolate FDt107): (A) fertile plant, wet, (B) fertile plant, dry, (C–E,O) capsules, dry, (F) exothecial cells, (G–J) leaf transverse sections, (K,P) perichaetial leaves, (L,M,Q,R,T,U,V) stem leaves, (N,W) upper-leaf cells, (S,X) mid-leaf cells, (Y,BB) basal leaf cells, (Z,AA) gemmae. Scale bars: 2 mm for (A,B); 0.5 mm for (C–E,O); 1 mm for (K–M,P–R,T,U,V); 100 μm for (F–J,N,S,W–BB).

Figure 4

Line drawings of gametophyte of Dicranella thermalis (from: Holotype, isolate CF1-1): (A–C) leaf transverse sections, (D,E) view of sterile plants, (F–H) leaves, (I) upper-leaf cells, (J) mid-leaf cells, (K) basal leaf cells. Scale bars: 5 mm for (D); 2 mm for (E); 1 mm for (F–H); 100 μm for (A–C,I–K).

Figure 5

Line drawings of gametophyte and sporophyte of Calcidicranella obtusifolia (from: Russia, Krasnoyarsk Territory, Anabar Plateau, MW9031184, isolate RF42): (A,D) view of fertile plants, dry, (B) view of fertile plant, wet, (C) capsule, dry, (E) mid-leaf cells, (F) upper-leaf cells, (G,H) leaf transverse sections, (I) exothecial cells, (J–N) stem leaves, (O) perichaetial leaf, (P) basal leaf cells. Scale bars: 5 mm for (A,B); 2 mm for (C,D); 1 mm for (J–O); 100 μm for (E,F,I,P).

Figure 6

Line drawings of gametophyte and sporophyte of Protoaongstroemia sachalinensis (from: Holotype, isolate FDt122): (A) capsule, dry, (B) perichaetial leaf, (C,H,I) stem leaves, (D) mid-leaf cells, (E) upper-leaf cells, (F) view of fertile plant, wet, (G) fertile plant, dry, (J) basal leaf cells, (K–M) leaf transverse sections. Scale bars: 2 mm for (F,G); 1 mm for (B,C,H,I); 0.5 mm for (A); 100 μm for (D,E,J–M).