Chromosome Numbers for Three Mosses from Subantarctic Macquarie Island

Abstract

Chromosome numbers are recorded for the first time for three moss species from Macquarie Island. They are the first reports worldwide for Notoligotrichum australe (Hook. f & Wils.) G. Smith n = 7, and Muelleriella crassifolia (Hook. f & Wils.) Dus. subsp. crassifolia n = ca 36, while the chromosome number n = 26 for Pottia heimii (Hedw.) Hampe confirms previous reports for this species. Subantarctic Macquarie Island, (54*30'S, 158*57'E) politically part of Tasmania, Australia, is located about 1,000 km southeast of Tasmania. Macquarie Island is oceanic in origin, an emergent portion of the ocean floor and a crest of the Macquarie Ridge. is geographically isolated, with a cool harsh climate that is relatively uniform throughout the year and buffetted by incessantly strong westerly winds. The island is elongate, 34 km long and up to 5.5 km wide and almost rectangular. It consists of an undulating plateau more than 200 metres above sea (Selkirk et al. 1990). Geographical isolation and the prevailing climate have limited the diversity of vegetation. Neither trees nor shrubs occur. Bryophytes, lichens, and lowgrowing vascular plants are important components of the vegetation. Bryophytes are found from sea level to the highest altitude (433 m) and in all habitats. In some vegetation types such as mire or feldmark, bryophytes may be the dominant component. The bryophyte flora includes some 80-85 moss species and about 50 hepatics (Selkirk et al. 1990). Many bryophytes are sterile, reproducing only asexually (Bergstrom & Selkirk 1987). MATERIALS AND METHODS Moss specimens bearing capsules were collected by D. M. Bergstrom from Macquarie Island in October 1984. These were maintained under cold conditions similar to that on the island and examined for meiosis. These were stained in aceto-carmine then slides made permanent after freezing on dry ice and mounting in euparal (Ramsay 1983). Voucher specimens are at NSW. Specimens examined. -Notoligotrichum australe--on track in exposed feldmark east of Prion Lake, 200 m elev., Ramsay 118/84; on peat exposure between overland track and Red River, 150 m Elev., Ramsay 115/84; 150 m contour mark on overland track, NW of overland track and Brothers track junction in gravel/peat Ramsay 116/ 84). Pottia heimii-in runoff area directly N of ANARE Station, 0.5 melev., Ramsay 114/84; 119/84. Muelleriella crassifolia on rock in coastal tussock SW side of Wireless Hill, 5.0 m elev., Ramsay 117/84. RESULTS AND DIScuSSIoN Chromosome numbers were obtained here for three moss species on Macquarie Island, one in each of the families Polytrichaceae, Pottiaceae, and Orthotrichaceae. The only previous chromosome count for a moss on Macquarie Island is n = 10 for Bryum argenteum cited in Seppelt and Selkirk (1984). A number of cytological studies of other subantarctic and antarctic mosses have been reported (Inoue 1976; Newton 1980; Ochyra 1985; Przywara et al. 1984). Polytrichaceae. --Notoligotrichum australe (Hook. f. & Wils.) G. Smith, n = 7, Fig. 1-4. Notoligotrichum australe is one of three members of the Polytrichaceae on Macquarie Island where it is widely distributed occurring often on gravelly substrates. also occurs along the southeastern tablelands of the Australian mainland and in Tasmania (Scott & Stone 1976; Streimann & Curnow 1989). There are no previous reports of a chromosome number for N. australe, but the chromosome number for two subantarctic species (as Psilopilum antarcticum (C. Muell.) Par. and P. trichodon (Hook. f. & Wils.) Mitt.) is n = 7 (Fritsch 1991). The chromosome number n = 7 (Fig. 1-3) was obtained for collections of N. australe from three separate localities. The sporocytes are relatively small, as are all Polytrichaceae when compared to other mosses. At metaphase I of meiosis the seven bivalents included three large and four smaller ones (Fig. 1, 2, 4). Early separation of some bivalents, 0007-2745/95/359-362$0.55/0 This content downloaded from 207.46.13.129 on Mon, 27 Jun 2016 05:25:33 UTC All use subject to http://about.jstor.org/terms 360 THE BRYOLOGIST [VOL. 98