Grimmia consobrina Müll. Hal.

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 : 205-207

1. Grimmia consobrina Müll. Hal.

, Syn. Musc. Frond. 1: 785. 1849

( Fig. 3 ).

Lectotypus (designated by Muñoz, 1999: 176): Chile: sine loc., s.d., Pöppig s.n. ( NY [ NY00322587 ]!; isolecto-: BM [ BM000670949 , BM000670950 ]!).

Gametophyte. Dioicous. Female: innermost perichaetial leaf tubulose, to 3 mm long; male: plants in separate cushions with stem leaves mostly muticous, perigonia in multi-foliose buds, terminal and in leaf axils, several on a stem, innermost perigonial leaf concave. Growth form: dense cushions, adhering to substrate, plants radiculose at base, ascending, weakly branched, stems 0.5 to 1.5 mm high, capsule-bearing plants reaching up to 2.5 mm in height, central strand weak. Leaves becoming longer from stem base to tip, 1.5-3.0 mm long, of irregular length in capsule-bearing plants, imbricate, loosely arranged and slightly turned around stem, apices spreading when dry, older leaves quickly bending backwards when moistened, younger ones slowly so, patent to patulous when wet, in comal tuft patulous, from elongate-ovate, at insertion slightly narrowed, decurrent, auriculate leaf base tapering to acuminate apex, symmetric or falcate, muticous or with very short to elongate, bluntly denticulate hair-point, development of brood-bodies occurs on dorsal side of lamina in transitional part, destroying lamina cells only; leaf form in situ, at insertion and leaf base concave, lower laminal part keeled, upper part narrowly so, margin on one side recurved from insertion up to mid-leaf; basal paracostal cells elongate-rectangular, walls smooth or nodulose, towards margin several rows of shortrectangular or nearly quadrate, hyaline cells with smooth or nodulose walls reaching up to transitional part, at margin 2 rows of short- to elongate-rectangular hyaline cells with smooth walls, vanishing in transitional part or shortly above it, cells in transitional part and lower half of lamina rectangular with nodulose walls, in upper half nearly isodiametric, lumina irregular, oval or rounded; in transverse section leaf unistratose throughout, rarely bistratose in laminal part, at margin from above insertion up to below apical part one row of cells bistratose, in apex 2 or more rows bistratose. Costa, seen from dorsal side, strikingly small and thin from insertion up to broadest part of leaf compared to its stoutness in the laminal part, excurrent to hair-point, in transverse section costa weak on dorsal side at insertion, from leaf base up to apex rounded, channelled on ventral side to upper laminal part, narrowly so in apical part, at insertion 4 guide cells, the 2 outer belonging partly to paracostal cells, from leaf base up to apex 2 guide cells, a band of stereids, in upper laminal part a group of hydroids or substereids, in smaller plants stereids throughout.

Sporophyte. Seta arcuate wet, straight when dry, to 3.5 mm long. Capsule obloid, ribbed, pendent or horizontal, apophysis well-developed, stomata numerous in 2 rows in the apophysis, annulus of 3-4 rows of cells, detaching as spirals. Calyptra conical, mitrate, lobed, covering operculum. Operculum conical, rostrate, beak straight or slightly oblique. Peristome teeth erect when dry, lanceolate, in upper part slit in two small branches, lower half more or less perforate, densely covered with fine papillae, apices rarely with rounded papillae, the outer lowest plates nearly smooth or with few fine papillae, trabeculae broad throughout, distant, strongly protruding, prostome more or less developed. Spores 11-16 µm, finely granulose.

Diagnostic characters. – Gametophyte. Leaves becoming longer towards the apex of the stem ( Fig. 3B ); costa at insertion and in leaf base strikingly thin and small compared to its stout appearance in the laminal part ( Fig. 3F, G ); hydroids or substereids present in upper part of costa. Sporophyte. Capsule with well-developed apophysis; peristome teeth with trabeculae broad, distant, protruding.

Distribution, habitat and ecology. – Grimmia consobrina is essentially a south-temperate species known from southern Africa, Australia, New Zealand, and southern South America, but extending northwards along the Andes into Central America and the mountains of Mexico and California.

In South Africa and Lesotho ( Fig. 1 B) this species is common in the mountains of the Western Cape, where it occurs predominantly on nutrient-poor quartzitic sandstones in fynbos at altitudes from 450-2,000 m. It is especially common in the Cedarberg-Koue Bokkeveld-Groot Winterhoek area, extending eastward through the Cape Fold Mountains to the Swartberg, where it becomes more rare. Also known from two disjunct localities in the Drakensberg of Lesotho and adjacent South Africa, where it occurs on basalt rocks in alpine grasslands.

Notes. – A total of 64 specimens were examined, of which 16 had sporophytes, two of which had capsules in a suitable state. The nature of the costa in G. consobrina , which is strikingly thin at the insertion compared to its prominence in the laminal part, is unique among Grimmia species. The auriculate leaf base is best seen in well-developed leaves that are carefully removed, one by one, as the alar cells are very fragile. The more or less rectangular cell rows at the margins of the leaf base appear as a hyaline zone that narrows towards the broadest part of the leaf. Plants with leaves that are predominantly muticous have been named G. imberbis Müll. Hal. (a synonym of G. consobrina , see Maier, 2010).

In the study area, G. consobrina has frequently been misidentified as G. trichophylla , a species that is absent from South Africa and Lesotho.

Selected specimens examined. – South AfriCA. Prov. Western Cape: Cederberg, Zuurvlakte, c. 1150 m, 32°36’32”S 19°12’12”E”, 27.II.2000, Hedderson 13088 (BOL); Citrusdal Region, Cederberg State Forest Welbedacht Kloof, 900- 1300 m, 32°24’30”S 19°10’24”E, 17.II.2001, Hedderson 13678 (BOL); ibid. loc., E side of Langberg and slopes of Shadow Peak, 1550-1870 m, 32°23’20”S 19°10’25”E, 17.II.2001, Hedderson 13726 (BOL); Koue Bokkeveld Mountains, Twee Riviere, Suikerbossie Farm, c. 900 m, 32°40’30”S 19°16’02”E, 7.IV.2001, Hedderson 13754 (BOL).

Figures

Fig. 1. – Species richness (A) and geographic distribution (B-F) of Grimmia Hedw. species in South Africa and Lesotho. A. Distribution of species richness in the genus Grimmia Hedw. at the Quarter-Degree Square (QDS) scale; B. Grimmia consobrina Müll. Hal.; C. Grimmia donniana Sm. (stars) and G. elongata Kaulf. (circles); D. Grimmia fuscolutea Hook.; E. Grimmia kidderi James; F. Grimmia laevigata (Brid.) Brid.

Fig. 3. – Grimmia consobrina Müll. Hal. A. Transverse section of stem; B. Leaves; C. Outlines of transverse section of leaf; D. Cells in leaf base; E. Cells in transitional part of leaf; F-G. Transverse sections of leaves. [A-B, G: Hedderson 13754, BOL; C: Hedderson 13726, BOL; D - E: Hedderson 13088, BOL; F: Hedderson 13678, BOL].