Icmadophila eucalypti Kantvilas
Mycobank MB 517787
Thallus squamulose, whitish to pale grey, sometimes with a pale bluish, creamish or beige tinge, forming extensive, irregular colonies to 50 cm wide. Individual squamules 1–3.5(–5) µm wide, unevenly 130–350 µm thick and densely inspersed with crystals that fluoresce in polarised light and dissolve in KOH, arising from an effuse, very thin and transient, white primary thallus, scattered and discrete, or imbricate, rarely fusing together, stellate, rosette-like or, more typically, flabellate and with one side tightly adnate to the substratum and the other ascending, initially with crenulate, rather thickened margins, soon becoming nodulose, lobulate or palmately lobed and ± subfruticulose, sorediate; upper surface matt, smooth or minutely granular-scabrid (lens), in section with a pseudocortex 20–30 µm thick comprising randomly orientated, short-celled hyphae 3–5 µm wide, interspersed with occasional dead algal cells; lower surface white, ecorticate; soredia coarsely granular, 40–80 µm diam., concolorous with the thallus, originating at the lower surface of the squamule margins, soon eroding the margin somewhat and spreading acrosss the upper surface. Photobiont a unicellular green alga with globose cells 5–11 µm diam. Ascomata not seen. Pycnidia not seen. Secondary chemistry: thamnolic acid; thallus K+ vivid yellow, P+ orange. KC–, C–, UV–.
Icmadophila is a small, well-circumscribed genus of four species, characterised, inter alia, by: a crustose to squamulose thallus containing thamnolic acid, a Coccomyxa-type photobiont, sessile to stipitate ascomata and Icmadophila-type asci (Rambold et al., 1993). In the absence of fertile material, the inclusion of I. eucalypti in this genus was based on an evaluation of morphological, anatomical, ecological and chemical characters. Several attempts to extract DNA for molecular confirmation of this classification (by Dr H. Döring, Kew) were unsuccessful. Thus for the time being, this classification is provisional. However, the general morphology, anatomy and chemistry of the species are all consistent with what is found in Icmadophila as exemplified by the type species, I. ericetorum (L.) Zahlbr., I. japonica (Zahlbr.) Rambold & Hertel and the Australasian endemic, I. splachnirima (Hook. f. & Taylor) D. J. Galloway. The interpretation of the primary thallus of the new species is equivocal. Thin sections suggest that it is lichenised, albeit very weakly, although it does not seem to contain thamnolic acid. There is a possibility that this feature is better interpreted as a prothallus rather than a true thallus horizontalis, although the latter is found frequently in the family Icmadophilaceae. Occasional thalli of I. eucalypti also develop pinkish, gall-like thickenings on the surface and at the margins which are highly reminiscent of the ascomatal initials of other members of this family, including Dibaeis and Siphulella; however, sections did not reveal any early development of ascomatal tissues.
The specific epithet refers to the preferred host of the new species.
Icmadophila eucalypti is widespread in Tasmania where it occurs in wet eucalypt rainforest and cool temperate rainforest from lowland to subalpine elevations. It occurs on the lower, shaded parts of trunks of very large trees with a thick, fibrous bark. Eucalyptus obliqua L'Hérit., a common dominant in many Tasmanian wet eucalypt forest communities, is by far the preferred host species, although the fire-sensitive, rainforest conifer, Athrotaxis selaginoides Don, is also sometimes colonised. The new species forms extensive patches on the moist sides of such trees, where it associates with several other lichens with a similar squamulose growth form: Cladonia rigida (Hook.f. & Taylor) Hampe, Neophyllis melacarpa (F. Wilson) F. Wilson and Cladia schizopora (Nyl.) Nyl. Its predeliction for very old trees suggests that it may serve as an old forest indicator in ecological studies.
Type:—AUSTRALIA: Tasmania: Hartz Road near entrance to the National Park; 43°12’S, 146°47’E, 570 m; on moist trunks of old Eucalytpus obliqua in mixed forest; Jul 2007, Kantvilas 285/07 (holotype HO; isotype BM).
Additional specimens examined (paratypes):—AUSTRALIA: Tasmania: Algonkian Mountain; Kantvilas 145/90 (HO); West of Tahune Bridge, Kantvilas 21/98 (BM, HO); Weindorfers Forest; Mar1998, Kantvilas s.n. (HO); Mueller Road; Kantvilas 11/98 (HO); track to Wylds Craig; Kantvilas 616/03 (HO); Lake Helen; Kantvilas 21/04 (HO, K); Florentine Road; Kantvilas 306/05 (HO, K); W of Tahune Bridge, Coupe 8I; Kantvilas 275/07 (BM, HO, MSC).
Species corticola, squamulosa vel subfruticulosa, albida, acidum thamnolicum continens, sorediata, squamis 1–3.5(–5) µm latis, flabellatis, a thallo primario effuso, ephemero, albido enatis, ascomata conidiomataque ignota sed huic generi ob materiam chemicam, anatomiam morphologiamque adsignata.