Grimmia maido and Grimmia sanii, Two New Species from Africa

Abstract

The occurrence of Grimmia Hedw. (Bryopsida, Grimmiaceae) in Africa is insufficiently known and the recent bryological literature reports only a small number of species. Current revision of about 2400 herbarium specimens revealed many more species than so far reported. At this moment, the number of species is 32, a number that may be enlarged in course of the revision. Two taxa are described as new: Grimmia maido H. C. Greven sp. nov. is endemic to La Rdunion and Grimmia sanii H. C. Greven sp. nov. is endemic to the upper regions of the Drakensberg in South Africa. Following a revision of Grimmia Hedw. (Bryopsida, Grimmiaceae) for Europe (Greven 1995), a study of African specimens was initiated. Grimmia has been revised for Japan (Deguchi 1978) and for China (Cao & Vitt 1986), but revision of the African species has never been completed. Knowledge of the European species of Grimmia is important for the understanding of African species, especially because the occurrence of Grimmia species in northern parts of Africa (Morocco, Algeria, Libya, and Tunisia) should be linked with that in Mediterranean countries, and species from Afro-alpine habitats (Ethiopia, Tanzania, Kenya, Lesotho, etc.) should be compared with alpine European species. From the literature, there was no indication that Grimmia is richly represented in Africa. Kis (1985) listed only five recently recorded species from Uganda, Kenya, Tanzania, Zambia, Malawi, Zimbabwe, and Mozambique, whereas Magill (1981) mentioned only three for South Africa. About 2400 specimens were studied from BM, BR, E, EGR, FH, H, KRAM, L, MO, NY, PC, PRE, S, and U. After examination of these, a preliminary checklist of 32 African Grimmia species has been made; two of them are here described as new. GRIMMIA MAIDO H. C. Greven, sp. nov. (FIG. 1) Dioica. Planta laxe caespitosa, atro-viridis. Caulis usque ad 1 cm altus, erectus, parce divisus. Folia caulina sicca erecto-appressa, humectata patentia, ovato-lanceolata, acuminata, concava, canaliculata, inferiora imberbia, superiora longe pilifera, margine erecta, involuta. Cellulae laminae incrassatae, lumine haud sinuosulo, superne irregulariter bistratosae, superioribus quadrato-rotundatis, diametro 10-14 ptm, basilaribus quadratis, chlorophyllosis, rectangularibus, valde incrassatis. Fructus ignotus; a Grimmia laevigata (Brid.) Brid. difert, caule divise, foliis ovato-lanceolatis et lamina versus apicem irregularibus bistratosa. TYPE: AFRICA. LA RtUNION. View-point le Maido, at the end of RF 8, along trail to Grand B6nare, alt. 2150 m, 1995. 10.07, H. C. Greven & S. N. Khoeblal 4000.1 holotype, L; ALTA, MO, PRE isotypes; paratype same locality, R. & C.A. Crosby 8430, Mo 2226520). Plants growing in blackish, dense, flat, not very hoary, readily disintegrating patches, stems erect, branched above, 0.3-0.7 cm high; on exposed, horizontal, volcanic rock at high altitude. Dioicous. Leaves + 2 mm long, larger toward stem tips, crowded, appressed when dry, erecto-patent when moist, concave and not at all keeled, ovate-lanceolate, conspicuously narrowed at insertion, above gradually narrowing into short hair-point; margins plane, not thickened, incurved above. Areolation in basal part of leaf pellucid, unistratose, in upper part opaque, bistratose, with translucent unistratose ridges; basal marginal cells in 5-8 rows quadrate to shortly rectangular with conspicuously thickened transverse walls, 18-20 pm wide; basal paracostal cells elongate, in 3-5 rows, 40-60 pm long, with ? sinuose walls; cells above irregularly roundedquadrate, walls slightly incrassate, 10-14 pm wide in mid-leaf. Costa slender, not at all projecting on dorsal side, disappearing in upper lamina. Hairpoint 0.5-0.8 mm long, denticulate. Sporophytes unknown. Range.-La R6union. Comments.-This species was first found among a number of unidentified specimens from MO. In the autumn of 1995, we visited the locality and found the species at several places on the plateau between le Maido and le Grand B6nare, growing in flat blackish patches on exposed, horizontal, black volcanic rock. In the field, Grimmia maido is rather difficult to distinguish from blackish forms of G. affinis and G. laevigata that grow in the same habitat. It is closely related to the cosmopolitan G. laevigata and possibly derived from this species. However, there are some specific characters that distinguish it easily from G. laevigata. Most of the stems are frequently branched, and the leaf form is ovate-lanceolate, while G. laevigata usually has unbranched stems 0007-2745/96/428-432$0.65/0 This content downloaded from 207.46.13.120 on Thu, 15 Sep 2016 05:52:06 UTC All use subject to http://about.jstor.org/terms 1996] GREVEN: GRIMMIA MAIDO AND G. SANII 429