Introduction
Cape Horn, the southernmost point of South America, is probably most famous for its poor weather, which makes it frightful for sailors. Nevertheless, several early scientific expeditions travelled through the region and made collections (Galloway Reference Galloway2008), proving that the lichen flora is interesting and quite special. Galloway & Jørgensen (Reference Galloway, Jørgensen, Daniëls, Schulz and Peine1995) made a survey of the genus Leptogium in the region and recorded 16 species, with some additional unconfirmed earlier records. The second author and co-workers also collected lichens during a bryological excursion in the region, parts of which were revised by the first author who found important additions to the known Leptogium flora, bringing the total up to 19.
The Species
Leptogium adnatum P. M. Jørg. sp. nov.
MycoBank No.: MB805438
Leptogio patagonico similis sed thallo adpresso, complicato non-hirsuto, marginibus irregularibus.
Typus: Chile, Comuna Cabo de Hornos, Islas Holger, in Caleta Holger off NE coast of Isla Navarino, 27 November 2001, W. R. Buck 41478 (NY—holotypus).
(Fig.1A)
A, Leptogium adnatum, part of the holotype; B, L. auriculatum, part of the holotype. Scales: A & B=1 mm. Photographs: J. Berge.
Thallus crustaceous, spreading, composed of densely packed, irregular squamules often more or less erect, forming intricate patterns, but in outer parts developing more fully into vertical, appressed, dark greyish blue orbicular lobes, which are firmly attached to the rocks and up to 1 mm broad. In section 100–150 µm thick with a single cortical layer on both sides, non-hairy.
Apothecia sparse, sessile, 1·5–2·0 mm broad with concave, brown disc and 200–250 µm wide, dark grey-blue cellular thalline margin, often with small lobules attached, when developed among the packed squamules appearing urceolate. Asci of Leptogium-type; ascospores poorly developed, narrowly ellipsoid, colourless, sparingly submuriform, 35–45×10–12 µm.
Conidiomata not observed.
Notes
This is an unusual, rather crust-like species which covers the rocks to which it is appressed (hence the epithet) and is carpet-like. Though the type collection on closer inspection was found to consist of closely packed, intricately folded lobes, it is possibly related to L. patagonicum Zahlbr. due to the kind of lobes, in spite of the lack of hairs. Similar modifications of that species with densely packed lobes are found in Buck's collections, but they all have distinctly hairy lower surfaces. The different apothecia and spores of the material described here cannot be explained as modifications, so a new taxon is established. The ascospores rather indicate a relationship with L. australe (Hook. f. & Taylor) Müll. Arg., which is one of the hairy species though with quite different subpedicillate apothecia with blackish brown discs (Galloway & Jørgensen Reference Galloway, Jørgensen, Daniëls, Schulz and Peine1995). That species frequently occurs higher up on maritime rocks, amongst mosses and grass in the region, and is quite distinctive. A superficially more similar species is L. puberulum Hue, a rare species in the region, which is shortly hairy below, with a different ecology (non-maritime, on exposed rocks more inland) and shorter and broader ascospores.
Habitat and distribution
Leptogium adnatum was collected on coastal rocks in the supramarine zone, a rather unusual habitat for a Leptogium. However, the high rainfall in the region appears to wash the salt out and make such habitats better available for lichens. The species is as yet known only from maritime rocks in the Cape Horn region, and may be a local endemic.
Additional specimens studied. Chile: Comuna Cabo do Hornos, Parque Nacional Alberto Agostini, N shore of Isla Gordon, extreme SW end of Bahia Romanche, 2012, W. R. Buck 59091 (NY); W end of Isla Gordon, extreme SE end of Brazo Intuil of Paso Darwin, 3 ii 2012, W. R. Buck (NY); Isla Grande de Tierra Fuego, W coast of Caleta Olla, at E end of Brazo Noroeste of Beagle Chanel, 2012, W. R. Buck 58907 (NY); N shore of Isla Hoste, SE end of Estero Fouque, opposite Punta Blanco, 21 i 2012, W. R. Buck (NY).
Leptogium auriculatum P. M. Jørg. sp. nov.
MycoBank No.: MB805439
Leptogio decipiente similis sed thallo non hirsuto, lobis auriformis et marginibus incrassatis granulatis.
Typus: Chile, Comuna Cabo de Hornos, Isla Navarino, Pantalon del Este, c. 9 km E of Puerto Williams, small stream near mouth of Beagle Channel, 25 November 2001, W. R. Buck 41349 (NY—holotypus).
(Fig. 1B)
Thallus foliose, consisting of orbicular, often imbricate, 5–7 cm diam., auriform lobes 0·5–1·0 cm wide, with undulating margins. In section 150–250 µm thick with the cortex in a single row of isodiametric cells; margins thickened, bursting into soredioid clusters of granular isidia, these sometimes also roughening the otherwise quite smooth, shiny, dark grey-brown upper surface. Lower surface paler, smooth, without hairs.
Apothecia and conidiomata unknown.
Notes
Easily recognized by the auriform lobes with thickened, often granular margins, unlike any other species in the region except for the unrelated L. decipiens P. M. Jørg. which has hairs on the lower surface and more elongated lobes with cylindrical isidia. Though L. auriculatum has no hairs on the lower surface, it appears to be most closely related to L. patagonicum Zahlbr., a species which is well represented in these collections and the identity of which was first clarified by Jørgensen (Reference Jørgensen2001), a view which these collections confirm.
Habitat and distribution
The type was collected on wet rocks along a small stream in a disturbed Nothofagus forest, and the second specimen on large rock outcrops in a mostly unforested region.
Additional specimen studied. Chile: Communa Cabo do Hornos, Parque Nacional Alberto Agostini, Isla Grande de Tierra Fuego, Fiordo Garibaldi, small island just SW of where Ventisquero Pisco Azules reaches the fiord, 2012, W. R. Buck 59280 (NY).
Concluding remarks
The discovery of two new Leptogium species in this region is remarkable, even if the region is poorly accessible and it is difficult to make collections there. It adds to the number of endemics in the subantarctic element.
