Krogia macrophylla Kistenich & Timdal

Kistenich, Sonja, Rikkinen, Jouko K., Thues, Holger, Vairappan, Charles S., Wolseley, Patricia A. & Timdal, Einar, 2018, Three new species of Krogia (Ramalinaceae, lichenised Ascomycota) from the Paleotropics, MycoKeys 40, pp. 69-88 : 78-82

Krogia macrophylla Kistenich & Timdal sp. nov. Fig. 4

Diagnosis.

The species differs from all other species of the genus in forming larger (up to 3 mm wide, vs. up to 0.3-1.5 mm wide in the other species) squamules and, except for K. coralloides , in producing an unknown compound resembling boninic acid.

Type.

New Caledonia, Province Sud, Mont Mou Nature Reserve, in low dense mist forest along foot path to the mountain summit, on tree trunk, 22°03'39.66"S, 166°20'53.54"E, 1162 m alt., 2016-09-26, J. Rikkinen 36077 (H, holotype [TLC: unknown compound resembling boninic acid; GenBank: MH174288 (ITS)]; PC, isotype).

Description.

Thallus effuse, squamulose; squamules up to 3 mm wide, at first rounded, later becoming incised and deeply divided into up to 1 mm wide lobes, ascending even when young, often imbricate, flattened or with an up-turned tip, greyish-green, with patches of purple (K+ bluish-black) spots, epruinose, glabrous; margin concolorous with upper side, not fibrillose; lower side white; isidia (present in one specimen) attached marginally to the squamules, simple or sparingly branched, up to 1.6 mm long and 0.2 mm wide. Upper cortex composed of thick-walled, irregularly orientated hyphae with angular to cylindrical lumina, 50-80 µm thick, lacking an epinecral layer, not containing crystals (polarised light!); algal layer 25-35 µm thick, filled with crystals dissolving in K; medulla composed of loosely interwoven hyphae, upper part containing crystals dissolving in K; lower cortex lacking; prothallus lacking. Apothecia up to 1 mm diam. when simple, often forming aggregates up to 6 mm diam., pale to medium brown, with purple patches, plane to weakly convex, with an indistinct, slightly paler, often flexuose margin; excipulum pale brown to colourless, composed of radiating, closely conglutinated, thick-walled hyphae with narrowly cylindrical lumina, not containing crystals; hypothecium pale brown to colourless, composed of closely conglutinated, thick-walled hyphae with narrowly cylindrical lumina, not containing crystals; epithecium colourless, not containing crystals; purple pigment occurring patchily in exciple, hypothecium and hymenium. Ascospores filiform, curved, simple, spirally arranged in ascus, ca. 20-30 × ca. 1.0 µm (estimate of curved spores). Conidiomata not seen.

Chemistry.

An unknown compound resembling boninic acid (major) and traces of additional compounds. Spot tests: all negative, except for purple patches being K+ deeper purple to bluish-black.

Distribution.

The species is known from three localities in New Caledonia.

Ecology.

The species grows on tree trunks in moist or wet tropical forests (Figs 5 A–C). Two collections are from montane mist forests and one from a low-elevation rainforest, all on ultramafic soils typical of the southern part of Grande Terre (main island of New Caledonia). It prefers shaded basal trunks that are otherwise mainly dominated by epiphytic bryophytes and/or leprarioid lichens.

Etymology.

The specific epithet refers to the large squamules.

Remarks.

In the examined material, one specimen (Rikkinen 38565) is isidiate, whereas the others are not. Our first assumption, that two species were involved, was not confirmed by the phylogeny (Fig. 1) and it appears that vegetative dispersal units, isidia, are produced occasionally in K. macrophylla . The only other isidiate species of Krogia is K. isidiata ; see that species discussion.

Krogia macrophylla has a similar secondary chemistry to K. coralloides (an unknown substance resembling boninic acid as the major constituent) but differs in lacking the boninic acid that co-occurs as the major constituent in K. coralloides ( Timdal 2002). Krogia coralloides forms smaller (up to 1 mm wide), more linear lobes with often down-turned tips.

Additional specimens examined.

New Caledonia. Province Sud: Blue River Provincial Park, dense riparian forest near camp site on river bank, on tree trunk, 22°05'54.79"S, 166°38'20.24"E, 200 m alt., 2016-09- 22, J. Rikkinen 35037 (H); locality data as for holotype, J. Rikkinen 36047 (H); Mont Humboldt Nature Reserve, close to Mont Humboldt refuge, in low dense mist forest along foot path from shelter towards the mountain summit, on tree trunk, 21°52'46.79"S, 166°24'49.17"E, 1320 m alt., 2011-11-09, J. Rikkinen 38565 (H).

Key to the species of Krogia