Grimmia orbicularis Wilson

Eva Maier, Michelle J. Price & Terry A. Hedderson, 2017, A revision of Grimmia (Grimmiaceae) from South Africa and Lesotho, Candollea 72 (1), pp. 199-230 : 219-220

9. Grimmia orbicularis Wilson

in Engl. Bot. Suppl. 4: n. 2888. 1844

( Fig. 11 ).

Lectotypus (designated by Muñoz & Pando, 2000: 58): united Kingdom. England: St. Vincents Rocks , II.1837, Eagle s.n. ( BM [ BM000670185 ]!; isolecto-: BM [BM000670193]!).

5 Grimmia leptotricha Müll. Hal. in Hedwigia 38: 120. 1899.

Lectotypus (designated by Muñoz & Pando, 2000: 69): South AfriCA: “In monte ‘Boschberg’ prope Somerset-East, Promont. bon. Spei” , s.d., MacOwen s.n. ( BM [ BM000575823 ]!), synonymized by Maier (2010: 254).

Gametophyte. Monoicous. Female: innermost perichaetial leaf 1.8-2.0 mm long, sheathing to mid-leaf or two third of leaf length, concave, sheathing part transparent, costa stout in upper part, excurrent in broad, nearly smooth hair-point; male: perigonia in branches far below perichaetium as multifoliate buds on short stalks, the concave, hyaline lower part of innermost perigonial leaf sheathing, suddenly narrowed to acute apical part, costa vanishing below apex, paraphyses present. Growth-form: cushions dense, compact, strongly attached to substrate, stolons originating from mostly present tomentum, leaflets scale-like, appressed to stem, apices patent, plants erect, branched, stems to 30 mm high, central strand developed. Leaves 1.0-1.5 mm long, crowded, appressed to stem when dry, bending backwards when moistened, erecto-patent when wet, from ovate leaf base lanceolate or elongate-lanceolate, broadest at mid-leaf, tapering to obtuse apex, hair-point very short to elongated, nearly smooth; leaf form in situ, at base concave, laminal part keeled, margins on both sides from below to above mid-leaf recurved, rarely on one side only; basal paracostal cells elongate-rectangular, walls nodulose, at margin some cell rows rectangular to quadrate, transverse walls thickened, smooth, cells in transitional part short-rectangular, sinuose, in upper laminal part isodiametric, lumina rounded; seen in transverse section, leaf base and lamina unistratose throughout, margin unistratose except one bistratose cell row on one, rarely on both sides near apex. Costa, seen on dorsal side, narrowed at leaf base, gradually enlarged to laminal part, excurrent into hair-point, costa, seen in transverse section, on dorsal side rounded, at insertion and leaf base mammillose, on ventral side in basal part widely channelled, in laminal part channelled, at insertion and in leaf base 4 guide cells, occasionally the 2 outer ones contiguous with the basal cells, in laminal part 2 guide cells, a median group of hydroids, vanishing below apical part.

Sporophyte. Seta to 2.0-3.0 mm long, arcuate, vaginula 0.8 mm long, cylindrical, with ochrea. Capsule exserted, pendulous, ovoid, finely ribbed, exothecial cells elongated thin-walled, stomata large on base of capsule, neck none, annulus of two or three rows of cells, detaching easily as groups or singly. Calyptra cucullate. Operculum conical, mammillate, margin smooth, formed by a row of nearly isodiametric cells, in conical part cells irregular, walls thin. Peristome teeth erect, spreading when dry, broadly lanceolate, in upper half split into two or four divisions, occasionally imperfect or rudimentary, in places interconnected by anastomosis, separated down to the insertion, dorsal and ventral sides densely covered with fine papillae, trabeculae small, distant, in lower third sharply protruding. Spores 10-13 µm, smooth.

Diagnostic characters. – Gametophyte. Leaves broadest at mid-leaf, margins recurved on both sides at mid-leaf, unistratose except at apex on one side, rarely on both sides in one cell row, basal paracostal cells elongate-rectangular ( Fig. 11 E, F), walls nodulose. Sporophyte. Peristome teeth in upper half divided into two to four divisions, in places interconnected by anastomosis.

Distribution, habitat and ecology. – Grimmia orbicularis is a thermophilous species known from Mediterranean areas of Europe and North Africa extending northwards to the UK and the Netherlands, eastwards to Tibet and adjacent China, and also known from a scattering of localities in the southwest USA. In the southern hemisphere it is known only from South Africa, New Zealand and Uruguay.

In South Africa and Lesotho ( Fig. 2 C) Grimmia orbicularis is an uncommon species, mostly known from shales, or occasionally dolerite, in karoo (mostly succulent karoo) vegetation at low to medium elevation (300-1,000 m) in dry inter-montane valleys of the Western Cape, but with outlying populations in similar vegetation types in the Northern and Eastern Cape Provinces and the Free State.

Notes. – A total of 13 specimens were seen, one had sporophytes of which a few capsules were in a suitable state for examination. For differentiation between G. orbicularis and G. pulvinata see comments under the latter species.

Selected specimens examined. – South AfriCA. Prov.Western Cape: Cederberg, Algeria Forestry Station, N-facing side of valley behind campsite , 500-700 m. 32°19’42”S 19°05’37”E, 26.II.2000, Hedderson 13047 ( BOL); McGregor area , Riviersonderend Mountains , Boesman’s Kloof , cliffs along path below De Galg , 34°00’40”S 19°42’30”E, c. 1000 m, 28.IX.2003, Hedderson 15264 ( BOL, G); Swellendam–Ashton area , W slopes of the Langeberg at the farm Sitruspoort , 33°56’50”S 20°16’20”E, c. 350 m, 11.X.2003, Hedderson 15285 ( BOL); 14 km S of Oudtshoorn , along road to George , small kloof above road , 500 m, 18.I.1979, Magill 6097 ( PRE).

Figures

Fig. 2. – Geographic distribution of Grimmia Hedw. species in South Africa and Lesotho. A. Grimmia longirostris Hook.; B. Grimmia montana Bruch & Schimp.; C. Grimmia orbicularis Wilson; D. Grimmia pulvinata (Hedw.) Sm.; E. Grimmia pygmaea Müll. Hal.; F. Grimmia sessitana De Not. (circles) and G. tortuosa Hook. f. & Wilson (star).

Fig. 11. – Grimmia orbicularis Wilson. A. Transverse section of stem; B, C. Leaves; D. Outlines of transverse section of leaf; E, G. Cells in leaf base; F. Cells in transitional part; H. Transverse section of leaf. [A: Hedderson 15285, BOL; B, E: MacOwen s.n., BM; C, F-H: Hedderson 15264, BOL; D, Hedderson 13047, BOL]