Grimmia torngakiana
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Authority
Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.
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Family
Grimmiaceae
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Scientific Name
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Description
Latin Diagnosis - Plantae atrae vel atro-virides, pulvinas rotundatas formantes; caules graciles, partibus adultioribus denudatis. Folia caduca plus minusve uniformia, in statu sicco flexuoso-torta, 1.5-2.0(-2.3) mm longa, lineari-lanceolata, in regione superna carinata; folia superna aristis denticulatis hyalinis curtis (120-290 µm) armata, infema mutica; margines plani, omnino usque circa basem bistratosi; costae robustae, in apicem evanidae; laminae in superna 1/3 regione irregulariter bistratosae; cellulae omnes guttis oleis prominentibus gaudentes, in regione superna rotundatae vel subquadratae, 14-20 µm, in mediana 12 /µm longae, 9-10 µm latae, perincrassatae et valde sinuosae, basem versus incrassatae et juxta costam sinuosae, marginem secus seriebus cellularum hyalinarum parietibus tenuibus praeditae, marginem distinctum in forma litterae - V formantes. Antheridia archegonia sporophytaque non visa.
Species Description - Dark green to black plants, in rounded cushions or tufts; stems slender, 0.8-2.5 cm long, the older parts denuded, sparingly branched. Leaves caducous, of ± uniform size throughout, flexuose- contorted when dry, erect or erect-spreading when moist, 1.5-2.0(-2.3) mm long, linearlanceolate, keeled above; lower leaves muticous, upper leaves with short (120-290 µm), denticulate hyaline awns; leaf margins plane, bistratose nearly to the base; costae stout, ending in apex; lamina irregularly bistratose in upper 1/3; all cells with prominent oil globules, upper cells rounded to ± quadrate, not or only slightly incrassate, 14-20 µm, obscure; mid-leaf cells 12 µm long, 9-10 µm wide, very incrassate, strongly sinuose; cells toward base 30-32 µm long, 12 µm wide; basal cells 3-4 times as long as wide, incrassate and sinuose towards costa; 3-4 marginal rows of cells thin-walled and hyaline, forming a distinct V-shaped border. Sex organs and sporophytes unknown.
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Discussion
Grimmia torngakiana is described as new from high altitudes at Nachvak, northern Labrador, Canada. Its most distinctive features are caducous leaves that are contorted when dry, large leaf cells and terricolous habitat.
Type: CANADA. Labrador: Nachvak Fiord, Minaret Plateau, 58°55' N, 64°00' W, 1700 m elevation,turfs on mineral soil in seepage from late snowbeds, 22 Jul 983, Hedderson 1893 (holotype nfld; isotypes: CANM, MICH).
Additional specimens examined: Same as the type, fedderson 1892, 1898 (NFLD).
The species is named after the legendary Inuit orcerer Tomgak, rather than after the mounains (Tomgat) which the sorcerer is believed to inhabit.
In aspect, Grimmia torngakiana is quide un-like any other species of Grimmia because its leaves are readily caducous and distinctly conorted when dry. At first glance the plants even took andreaeoid, and the large cells with promnent oil globules enhance the resemblance to that genus. Grimmia torngakiana bears some microscopic resemblance to G. elongata Kaulf, which also has mid- and lower leaf cells very incrassate and somewhat sinuose, a short hair point and relatively short basal cells. However, G. elongata has much smaller cells in the upper part of the leaf (only 8 µm), a smooth hair point and leaf margins recurved on one side below. The mid-leaf cells of G. torngakiana are also much more sinuose than those of G. elongata.
In aspect G. torngakiana somewhat resembles Grimmia incurva Schwaegr., which has leaves strongly contorted, or sometimes crisped, rather than flexuose-contorted when dry. Microscopically, G. torngakiana is easily distinguished from G. incurva because ofthe leaves which are mostly pistratose above, the large obscure upper leaf cells, find the plane leaf margins. Although the midleaf cells of G. incurva are somewhat incrassate they are never as strongly sinuose as those of G. yorngakiana.
In a genus of saxicolous species (Crum & Anderson 1981; Smith, 1978) the terricolous habitat pf Grimmia torngakiana is noteworthy. All the i.:ollections are from acidic mineral soil in seepage from snowbeds, where the plants were associated with Dicranoweisia crispula (Hedw.), Brid., Kiaeria falcata (Hedw.) I. Hag., Oligotrichum falcatum Steere, Psilopilum cavifolium (Wils.) I. Hag. and Racomitrium elongatum Ehrh.) Frisv.
Grimmia torngakiana is thus far endemic to northem Labrador; the only moss that is so. The occurrence ofan endemic in the Tomgat Mountains is, however, not totally unexpected, since land surfaces in the Tomgat may have been unglaciated for a period sufficient to allow speciation. Ives (1974, 1978) presented strong geomorphological evidence for some sites having been unglaciated, and the Nachvak region is one of the most likely of these. The populations of Grimmia torngakiana all occur at the highest altitudes and well within the most highly weathered surfaces (Ives, 1974, 1978). Thus, these sites may well never have been overriden by glacier ice. The Nachvak region bryoflora includes a number of other geographically isolated moss species or forms, e.g., Grimmia atrata Hoppe & Homsch., an unusually distinct form of Mielichhoferia mielichhoferi (Hook.) Loeske (Brassard & Weber, 1978), Hydrogrimmia mollis Loeske and Andreaea nivalis Hook. (Hedderson & Brassard, 1986), and these also support isolarion of the bryoflora for a long period.