Philonotis angustiretis Broth. ex T.J. Kop., 2015

Koponen, Timo, 2015, Notes on Philonotis (Bartramiaceae, Musci). 14. Philonotis angustiretis, species nova, from N. W. Himalaya, Arctoa 24 (1), pp. 24-26 : 24-25

Philonotis angustiretis Broth. ex T.J. Kop. , species nova ( Fig. 1 )

Holotype: N. W. Himalaya, [Kashmir], leg. J. F. Duthie 5 914 (H-BR, as Philon . angustiretis Broth. n. sp.).

Plants brownish, tiny and slender, to 6 mm tall; habitus that of a typical Philonotis . Rhizoids brown, minutely papillose. Stems slender, green. In cross-section the outer wall of epidermal cells thin, colorless, other parts of the wall thick; below the epidermis are one or two layers of brownish cells with thick walls, inner cortical cells thin-walled, larger. Central strand present. Deciduous propagules with a stalk and a few acute leaves present on stems. Leaves on stem below perichaetium erect to erect spreading and slightly secund when dry, erect spreading when wet, slightly concave and widest at the insertion, ca. 0.2 mm wide and ca. 1 mm long, tapering gradually to an acuminate apex. Leaf margins smooth at base, minutely geminate at mid-leaf, and serrulate near the apex, also revolute at proximal leaf base. Innovations 4 mm long, leaves of innovations similar to stem

1 – Finnish Museum of Natural History LUOMUS, Botany Unit (Bryology), P. O. Box 7, FI-00014, University of Helsinki, Finland; and Finnish-Chinese Botanical Foundation, Mailantie 109, FI-08800 Lohja, Finland; e-mail: [e-mail]

leaves but smaller. Leaf alar cells ± quadrate, smooth and thin-walled, 10–15 µm wide; cells between alar cells and costa short rectangular, 7.5–10 u 17–27 µm, smooth. Cells at mid-leaf thick-walled, 5–7.5 u 15–27 µm, with a distinct papilla at the distal cell end. Distal laminal cells gradually narrower, thick-walled with a papilla on the distal cell end. Leaf costa not reaching the apex, 37 µm broad near base, distally with a few protruding cell ends. In cross-section nearly all cells are stereidal, thick-walled. Dioicous. Perichaetia terminal, innovations below perichaetial leaves numerous, up to 7. Perichaetial leaves gradually long acuminate from a convex base, erect, up to 1.2 mm long; basal leaf cells of innermost leaves thin-walled, wider and longer than basal leaf cells of vegetative leaves, cells on proximal leaf base linear; leaf margins nearly smooth or minutely serrate, costa fading below apex, paraphyses few. Perigonia terminal, bud-like, below perigonium one innovation continuing the growth. Perigonial leaves brownish concave at base, abruptly acuminate, erect, up to 1.3 mm long, cells in concave leaf base thin-walled; leaf margins serrulate at narrow proximal part; costa excurrent; paraphyses numerous. Seta slender, smooth, up to 1 cm long. Capsule striate when dry, 1.5 mm long and 1 mm wide, gibbous, horizontal to slightly nodding. Operculum short convex. Peristome complete, double. Spores 17–25 µm, minutely papillose.

The diagnostic characters of Philonotis angustiretis are: (1) the small size of the plants with a tiny capsule, (2) ± quadrate, thin-walled, leaf alar cells, (3) basal leaf cells near costa elongate and smooth, and (4) distal laminal cells thick-walled with distinct papilla at the distal cell end. These characters and ± horizontal capsule with a complete peristome show that it is a species of Philonotis section Philonotula . In that section, Philonotis thwaitesii Mitt. has quadrate basal leaf cells forming a broad area of several cells extending from the border to the costa. P. lancifolia Mitt. and P. runcinata Ångstr. have similar leaf shapes, revolute leaf borders with geminate teeth and distinct papillae on laminal cells. These three species seem to be the closest relatives of P. angustiretis . However, they are larger plant species, the angular alar group of thin-walled, quadrate cells is lacking, and proximal laminal cells are mamillose/papillose.

A key to southeast Asiatic species of Philonotis sections Bartramidula and Philonotula and a discussion on how to distinguish them is in Koponen (2010b), while a key and discussion of the species of the section Philonotis was published by Koponen et al. (2012).

The exact type locality of Philonotis angustiretis is not known. On the basis of Duthie’s tour reports (1893, 1894) it was collected somewhere in Kashmir. Duthie gave the collecting localities of some vascular plants, but mentioned mosses only once: “The whole of the mosses, of which a large collection was made, have been sent to Dr. Brotherus at Helsingfors in Finland for determination” ( Duthie, 1893) .

Brotherus’ study (1898) of N. W. Himalayan mosses confirms that Duthie collected them in 1892–93. Duthie (in Brotherus, 1898) also gave an account of the characteristics of the nature within his study area, Kashmir and the “countries” Astor, Baltistan and Gilgit. Brotherus had listed specimens from these areas and, in addition, from Kájnág, Srinager and Pamir. Duthie’s collector numbers in Brotherus (1898) run from 10830 to 17799. Since the number of the type of P. angustiretis is 5913, it probably was collected from an early phase of Duthie’s excursions. Later, Brotherus and Duthie corresponded, and Duthie sent 17 letters to Brotherus in 1892–1902 ( Koponen & Piippo, 2002).

Figures

Fig. 1. Philonotis angustiretis T.J. Kop. (from the type). 1: Leaves. 2: Perichaetial leaf. 3: Old and young capsules. 4: Leaf border and laminal cells at mid-leaf; 5. Leaf base.