Brachymenium perspinidens (Broth.) H.Rob. & G.K.Golinski, 2020

Robinson, Harold & Golinski, G. Karen, 2020, Notes on Brachymenium in Guyana with a new species from Mt. Ayanganna, PhytoKeys 154, pp. 11-17 : 11

Brachymenium perspinidens (Broth.) H.Rob. & G.K.Golinski comb. nov. Figure 1D

Bryum perspinidens Broth., Bot. Jahrb. Syst. 24: 246. 1897. Britische Ostafrika, Seengebiet: Ru- Nssóro, 3300-3600 m (Uganda: Ruwenzori, heather forest 10-12000'), Scott Elliot 266, Sterile. Rhodobryum perspinidens (Broth.) Pócs, in Bizot & Pócs, Acta Bot. Acad. Sci. Hungaricae 25: 257. 1979 [1980]. With record of species from Tanzania, also sterile. Ochi (1972) indicated the species was rather an oddity in Bryum Hedw. subgenus Rhodobryum Schimp. in which he placed it.

Notes.

Placement of the new species in Brachymenium is based on the capsules being erect with an inner peristome being a low membrane lacking segments or cilia, the traditional distinctions of the genus. Recent DNA studies ( Pedersen et al. 2003, Pedersen and Hedenas 2005; Cox and Hedderson 2003) indicate that species that have been placed in the genus Brachymenium are mostly in basal branches of the Bryaceae while Bryum species are more derived. According to such studies, the genus Brachymenium is more entangled phyletically with the genus Rhodobryum (Schimp.) Hampe, Linnaea 38: 663. 1874, a later established genus and Osculatia De Not., Mem. Reale Accad. Sci. Torino, ser 2, 18: 445. 1859 ( Robinson 1965; Ochyra et al. 2018). A survey of the illustrations in Brotherus (1904, 1925) shows an additional trend in Brachymenium that is lacking in typical Bryum , conical to rostrate opercula such is seen in the new species. In fact, within the present definition of Brachymenium , fully rostrate opercula occur in another species recently collected in Guyana.

Figures

Figure 1. Brachymenium ayangannensis H. Rob. & G. K. Golinski. A Leafy stem showing distorted leaves B distal part of leaves, showing well-developed pale margin and spiniform teeth on both margin and long-acuminate tip C remoistened erect capsule showing partially detached short-rostrate operculum D B. perspinidens (Broth.) H. Rob. & Golinski, distal part of leaf of holotype (from H) E tip of capsule mounted in Hoyer's solution showing short exostome and lack of well-developed endostome. The photographs were taken using a Leica DM 4 B Compound microscope, using a 5 x objective.