ANTARCTIC SPECIES IN THE GENUS DITRICHUM (DITRICHACEAE, BRYOPSIDA), WITH A DESCRIPTION OF D-GEMMIFERUM SP. NOV

There are five species in the genus Ditrichum Hampe in the Antarctic: D. heteromallum (Hedw.) Britt., D. conicum (Mont.) Mitt., D. austrogeo rgicum (Card.) Seppelt, D. lewis-smithii Ochyra and D. gemmiferum Ochy ra & Lewis-Smith. Of these, the first two are newly recorded from the region, whereas the last is described as new to science from material collected from the South Sandwich and South Shetland Islands, as well as from Marion Island in the Subantarctic and southern Chile. The new species is readily recognized by its short, rigid and strongly papillo se leaf subulae and the frequent occurrence of small, pale yellowish o r pale brownish rhizoidal gemmae. A key to determination of Antarctic species is provided and all species, except for D. lewis-smithii, are fully described and illustrated and their Antarctic and global distrib utions mapped. Ditrichum brotherusii (R. Br. ter.) Seppelt is excluded from the moss flora of Antarctica since information on its occurrence was based upon misidentification of the specimens. Blindia maxwellii Vitt from Campbell Island is briefly assessed and it is shown that it correctly belongs within Ditrichum as D. maxwellii (Vitt) Ochyra & Lew is-Smith. Lectotype is selected for Pseudodistichium austrogeorgicum C ard., and P. austrogeorgicum fo. brevifolium Card. and P. austrogeorgi cum var. longifolium Broth. in Card. & Broth. are reduced to synonymy with Ditrichum austrogeorgicum.