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. austrogeorgicum (Card.) Seppelt, D. lewis-smithii Ochyra and D. gemmiferum Ochyra & 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 papillose leaf subulae and the frequent occurrence of small, pale yellowish or 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 distributions 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 & Lewis-Smith. Lectotype is selected for Pseudodistichium austrogeorgicum Card., and P. austrogeorgicum fo. brevifolium Card. and P. austrogeorgicum var. longifolium Broth. in Card. & Broth. are reduced to synonymy with Ditrichum austrogeorgicum.