Methodology:

In October to November 2011 and January to February 2016, 83 specimens of 16 leafy liverwort species in the Adelanthaceae, Anastrophyllaceae, Cephaloziaceae, Cephaloziellaceae, Lophoziaceae, Lophocoleaceae, Plagiochilaceae and Schistochilaceae were collected from 12 sites on the Thatcher Peninsula.

The specimens, which were air dried at room temperature in clean paper packets within several hours of collection, have been deposited in the British Antarctic Survey herbarium (AAS see https://data.bas. ac.uk/metadata.php?id=GB/NERC/BAS/AEDC/00023). Dried plants were rehydrated in water and cleared in 10% KOH for 24 h at room temperature. All plants were then rinsed thoroughly with water and were bleached in a mixture of 30% hydrogen peroxide and 3% ammonium hydroxide (10:1 v/v) for up to 10 min. The plants were then washed thoroughly with water, were acidified in 5% lactic acid for 1 h and were stained with 0.01% aniline blue in lactic acid for 24 h. They were then removed from the staining solution, excess stain was drawn off on absorbent paper, and the plants were destained for at least 24 h in 80% lactic acid. From each sample, between 10 to 20 stems of each species, and at least 40 stems of Cephalozia badia, Cephaloziella varians and Clasmatocolea humilis, were then lightly squashed in 80% lactic acid on glass slides prior to observation under UV epifluorescence at x400 magnification (BX51 microscope, Olympus UK Ltd). The line intersection method described by McGonigle et al. (1990) was used to calculate the percentages of stem length colonised (SLC) by stained hyphal coils in rhizoid bases and stem epidermal cells, stained septate hyphae in stem epidermal cells, dark septate hyphae on stem surfaces, and dark septate coils in rhizoid bases and stem epidermal cells. A total of 4,442 intersections were examined, with up to 119 intersections being scored in each sample. The percentage of at least 30 rhizoids in each specimen that were colonised by hyphae was also recorded, with a total of 2,541 rhizoids being examined. Insufficient rhizoids were observed on the stems of Chiloscyphus koeppensis or Pachyglossa spegazziniana to derive means for rhizoid colonisation.

Instrumentation: BX51 compound microscope fitted with a UPlanApo x40 objective lens, a 100-W mercury short arc lamp and an ultraviolet fluorescence filter cube (U-MWU2, consisting of a BP 330-385 excitation filter, a DM 400 dichromatic mirror and an LP 420 emission filter; Olympus Life Science, Tokyo, Japan).

Data collection:

BX51 compound microscope fitted with a UPlanApo x40 objective lens, a 100-W mercury short arc lamp and an ultraviolet fluorescence filter cube (U-MWU2, consisting of a BP 330-385 excitation filter, a DM 400 dichromatic mirror and an LP 420 emission filter; Olympus Life Science, Tokyo, Japan).

Data quality:

Raw data are shown. The data have not been cleaned. Missing data in the Rhizoids colonised (%) column (indicating that no rhizoids were observed on the stems of plants) are indicated by NA.