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Taxonomy of Coscinodon arctolimnius (Bryopsida, Grimmiaceae) including a New Subspecies from Asia

1997; American Bryological and Lichenological Society; Volume: 100; Issue: 1 Linguagem: Inglês

10.1639/0007-2745(1997)100[50

1938-4378

Ross I. Hastings, Hironori Deguchi,

Lichen and fungal ecology

Coscinodon arctolimnius subsp. higuchii, a new subspecies from Pakistan and Mongolia, is characterized by its generally cucullate leaves that have long awns and plicae with long cells proximally. In addition, the leaf lamina is shorter and narrower than that of subsp. arctolimnius, a taxon known only from the type locality in the Northwest Territories, Canada. In 1974, W. C. Steere described Grimmia arctolimnia, from Great Bear Lake, Northwest Territories, Canada. Subsequently, he transferred the species to the genus Coscinodon (Steere 1977). Until now, the species has only been known from its type locality. While studying specimens of Coscinodon cribrosus (Hedw.) Spruce for a revision of the genus, Hastings came across a curious specimen in MO collected from Mongolia labelled cf Coscinodon cribrosus (Schubert M130). Although sterile the specimen was separable from typical C. cribrosus by its dark color and strongly cucullate leaves. In these features it was similar to C. arctolimnius. However, because the specimen was sterile it could not definitively be placed in the latter species, which is characterized sporophytically by the lack of a peristome, in addition to somewhat cucullate leaves with only short or absent awns. Hastings considered the Mongolian specimen likely a form of C. arctolimnius, but without sporophytes he could not be sure. Subsequently, Deguchi prepared a manuscript describing a new species of Coscinodon from Pakistan. Upon reviewing the manuscript, Hastings realized that this new species, which was based on fertile specimens, fit the description of C. arctolimnius, but also had distinct gametophytic characters. Both authors now agree that the specimens from Asia are best considered to be a previously unknown subspecies of C. arctolimnius and represent a significant range extension of that species. COSCINODON ARCTOLIMNIUS (Steere) Steere, Jour. Hattori Bot. Lab. 42: 446. 1977. Grimmia arctolimnia Steere, THE BRYOLOGIST 77: 230. 1974. TYPE: CANADA, NORTHWEST TERRITORIES. District of Mackenzie: On face of cliff on mineralized siliceous rock, in drainage channels, Labine Point, near Eldorado Mine, Port Radium, McTavish Arm, Great Bear Lake, (66005'N Lat., 118001'W Long.), 23 July 1948, Steere 10429. (holotype, NY!; isotypes widely distributed including ALTA!, BM!, CANM!, FH!, MICH!, MO!, NICH!, TNS!, UBC!, US!). Plants small, up to 10 mm high, in dense, darkgreen to black, occasionally hoary cushions. Stems moderately branched, densely foliate, with poorly developed central strand. Stem leaves imbricate and appressed when dry, erect-patent when moist; lamina 0.8-1.8 mm long, 0.3-0.8 mm wide at broadest part of leaf base, broadly keeled above, concave below, ovate-lanceolate; apex mostly cucullate and muticous, or inrolled on awned leaves, sometimes channelled, ending in a short to moderately long 0.2-0.5 mm (10-65% of laminal length), broadly attached, smooth, often inrolled, hyaline awn; upper lamina bistratose, lower and middle lamina patchy or streaky bistratose to unistratose; lamina strongly plicate, cells of plications always longer and narrower than adjacent laminal cells near base, extending to base either as a pleat or as a row of bistratose cells, upper lamina plication cells _ shorter; costa rather thick, percurrent, grooved above, costal cells long rectangular at base and mid-leaf, becoming quadrate above; margins plane below, inrolled above shoulder; upper laminal cells mostly quadrate, with evenly thickened, slightly sinuose walls, some cells oblate near margin, 7-12 sm wide, 5-14 sm long, medial cells oblate to short rectangular, with slightly sinuose walls, 9-12 Im wide, 7-20 jxm long, basal cells quadrate to short rectangular, with evenly thickened, ? sinuose longitudinal and transverse walls, 8-13 jxm wide, 9-33 I~m long, with 1-3 rows of hyaline marginal cells. Perichaetial leaves similar to stem leaves except somewhat larger, lamina 1.4-1.8 mm long, loosely areolate, cells thin-walled at leaf base, with long hyaline hair point reaching to 1.2 mm, broadly attached. Dioicous. Perigonia bud-shaped, usually 0007-2745/97/50-55$0.75/0 This content downloaded from 207.46.13.11 on Mon, 17 Oct 2016 05:36:49 UTC All use subject to http://about.jstor.org/terms 1997] HASTINGS & DEGUCHI: COSCINODON ARCTOLIMNIUS 51 with 10-15 antheridia in a single perigonium, inner perigonial leaves with wider, loosely areolate, convolute base and short, obtuse point. Setae 0.3-0.5 mm long, straight, twisted to left when dry. Capsules immersed, ovoid, wide-mouthed when deoperculate, 0.8-1.0 mm long, 0.7-1.0 mm wide at mouth; exothecial cells oblate near mouth, elongate-oblong in mid-capsule, with evenly thickened walls. Spores 8-11 jm, smooth. Peristome absent. Annuli imperfectly differentiated. Opercula conic, beak ca 0.6 mm long, weakly oblique to upright. Calyptrae campanulate, 1.1-1.5 mm long, covering entire mature capsule, strongly plicate. COSCINODON ARCTOLIMNIUS (Steere) Steere subsp. HIGUCHnII Hastings & Deguchi subsp. nov. (FIG. 1-19) TYPE: PAKISTAN. North-West Frontier Prov., Kaghan Valley, Batakundi; 2680 m alt., on boulder. August 26, 1990, Higuchi 19830 (holotype, TNS; isotype, HIRO). MONGOLIA. Chobd-aimak, Zaachansyn, Ulan-ul, Bergsteppe bei Chobd etwa, 11 VIII 1968, Schubert M130 (paratype, Mo). Folia caulina iis Coscinodon arctolimnius subsp. arctolimnius minora, apice plerumque cucullata aristata. Plicationis cellulae elongatae angustae costam simulantes. Lamina of stem leaves 0.8-1.4 mm long, 0.3-0.6 mm wide; apex mostly cucullate in both muticous and awned leaves, rarely just inrolled, commonly ending in a moderately long, 0.3-0.5 mm (33-65% of laminal length), smooth, hyaline awn; lamina strongly plicate throughout, plication cells longer and narrower than adjacent laminal cells, strongly resembling costal cells. Middle lamina unistratose. Medial cells oblate to quadrate, 9-12 jxm wide, 712 jxm long. Distribution and ecology.-Subspecies higuchii has been collected at two widely separated sites in Asia (Fig. 20). The holotype is from the Kaghan Valley in the Northwest Frontier Province of Pakistan. The paratype was collected in the Ulan Mountains, in Chobd-aimak Province of Mongolia. Unfortunately, due to the few collecting localities and paucity of label information, little is known about the microhabitat of this subspecies other than its occurrence on rocks. The region in Pakistan where the type was collected appears to be of arid mountains; it was collected at 2,680 m. The site in Mongolia was noted as being steppe with an elevation of 1,700 m. These general habitat conditions are typical for the genus. The discovery of this subspecies in Asia is highly significant phytogeographically in that C. arctolimnius was previously known only as an endemic to a single site on the shores Great Bear Lake, Northwest Territories, Canada (Steere 1977). A somewhat similar, widely disjunct, pattern has been oted for another memb r of the Grimmiaceae. Murray (1984) reported the first collection of the monotypic genus Indusiella in North America from a site near the Eagle River in northeastern Alaska. Previously, the species had been known only from central Asia, mostly near Mongolia in the former U.S.S.R., with a disjunct site in Chad. Murray also noted the occurrence of Coscinodon cribrosus at the Alaskan site. The latter species is rare in Alaska, but appears to be widely distributed in central Asia. COSCINODON ARCTOLIMNIUS (Steere) Steere subsp. arctolimnius (FIG. 21-33) Lamina of stem leaves 1.5-1.8 mm long, 0.6-0.8 mm wide; apex cucullate if muticous, otherwise inrolled, usually muticous but if awned short, 0.2-0.5 mm (10-25% of laminal length), smooth and hyaline; lamina strongly plicate throughout, plication cells same as adjacent laminal cells in upper and middle laminae, near base longer and more costal like. Middle laminae patchy to streaky bistratose. Medial cells quadrate to short rectangular, 8-13 jm wide, 8-20 Ipm long. Distribution and ecology.-Subspecies arctolimnius is known only from its type locality at Labine Point, on the McTavish Arm of Great Bear Lake, Northwest Territories (Fig. 20). It may be endemic to this site but given the paucity of collections in the region and the occurrence of another subspecies in Asia, it seems likely that specimens will be found outside of the type locality. Steere (1974) reported that Coscinodon arctolimnius, like the closely related Coscinodon cribrosus, grows on mineral-rich rock. The type specimen was collected within 100 meters of an extremely rich vein of native pitchblende (radium and uranium ore). Remarks.-The new subspecies is clearly placed within C. arctolimnius. Both subspecies of C. arctolimnius are characterized by eperistomate, immersed capsules. Gametophytically they have strongly plicate leaves with the plications typically extending to the base of the lamina either as a ridge or bistratose streak. The cucullate leaf habit is a feature unique to the species. The almost black color of the plants is also a striking feature. If fertile, subspecies higuchii is easily distinguished from the widespread C. cribrosus by the lack of a peristome on the former. But if the specimen is sterile, positive identification can be more problematic. The presence of a cucullate leaf apex should serve to distinguish it as a subspecies of C. arctolimnius; leaves of C. arctolimnius subsp. higuchii are almost always cucullate, while those of C. arctolimnius subsp. arctolimnius tend to be more cucullate in sterile rather than fertile specimens. All This content downloaded from 207.46.13.11 on Mon, 17 Oct 2016 05:36:49 UTC All use subject to http://about.jstor.org/terms 52 THE BRYOLOGIST [VOL. 100