Ochrolechia insularis Kantvilas & Elix
Mycobank MB 517802
Thallus crustose, intensely papillate, nodular or plicate, 0.3–4.5 mm thick, with upper surface white, smooth, matt to rather glossy, in places minutely speckled with white maculae, not pruinose or crystalline, forming irregular, undelimited patches to 10 cm across, not lobate or placodioid at margins; prothallus absent; individual nodules 0.5–1 mm wide, very densely crowded together in clumps to 5 mm wide, rather loosely attached, in section with a poorly developed cortex 15–30 µm thick composed of irregularly orientated, branched and anastomosing, short-celled hyphae 2–4 µm thick, overlain by a hyaline, epinecral layer; photobiont cells generally concentrated in a subcortical layer 40–100 µm thick, with individual cells globose, 6–15 µm; medullary hyphae loosely interwoven, 3–5 µm thick. Pycnidia immersed, visible as minute, pale brownish dimples or short cracks; condia bacilliform, 4–6.5 x 1 µm. Secondary chemistry: gyrophoric acid [major], lecanoric acid [minor or trace], 2’-O-methyllecanoric acid [± trace]; cortex K–, KC+ red, C+ red, P–, UV–; medulla K–, KC+ red, C+ red, P–, UV–.
In the absence of apothecia, the generic assignment of this species is tentative; however, its highly localised distribution warrants its description, and Ochrolechia is considered the most appropriate genus. Its position there is supported by its general appearance, in combination with its habitat ecology, chlorococcoid photobiont, secondary chemistry and bacilliform conidia. However, it is conceded that these characters may all be found in several other genera. From the thallus chemistry (cortex C+ red, medulla C+ red) this species appears to belong to O. africana Vain. group (Brodo, 1991), but morphologically it closely resembles O. tartarea (L.) A. Massal. Both O. tartarea and O. insularis are saxicolous and may develop an irregularly warty to nodulate-papillate upper surface. However, O. insularis differs in having a smooth and glossy upper surface (granular to powdery-tartareous in O. tartarea) and in lacking a prothallus (O. tartarea is surrounded by a paler prothallus) (Fletcher et al., 2009). In addition, the colour of the upper surface of O. tartarea varies from pale to dark grey (white in O. insularis) and the medulla of O. insularis reacts C+ red (C– in O. tartarea). At first glance, the new species is most reminiscent of members of the Pertusaria dactylina complex, which, in the southern Australian region, is well-represented on granite in such habitats (Kantvilas & Elix, 2008). However, these lichens are all isidiate rather then papillate, and contain salazinic, norstictic or hypothamnolic acids. One fragment of the new species (Kantvilas 332/08A, HO) supports a small cluster of stalked mazaedia of Sphinctrina leucopoda Nyl., a lichenicolous fungus previously unrecorded for South Australia. This widespread species is commonly known to parasitise the genera Pertusaria, as well Diploschistes and Rinodina (Tibell, 1987). It has not been reported previously from Ochrolechia.
The specific epithet refers to the habitat of the new species on Kangaroo Island off the southern coast of mainland Australia.
Ochrolechia insularis is a seemingly rare species, known only from the type locality where it occurs on large, sunny, windswept, granite boulders overlooking the sea but well above the normal extent of sea spray. It is associated with the typical community that dominates coastal granite rocks in southern Australia and Tasmania: Rinodina blastidiata Matzer & H. Mayrhofer, Tylothallia pahiensis (Zahlbr.) Hertel & Kilias, Xanthoria ligulata (Körber) P. James and species of Buellia, Caloplaca and Xanthoparmelia, especially X. conranensis (Elix) Elix and X. subprolixa (Nyl. ex Kremp.) Blanco et al. The species is extremely localised, and has been found on only a few large boulders; searches in similar habitats in the more general vicinity, as well as further afield such as on Flinders Island in Bass Strait, have failed to reveal any further localities. Thus it represents an extremely uncommon taxon of high conservation value, especially as much of the site where it grows is heavily degraded by the impact of sheep grazing and other disturbance.
Type:—AUSTRALIA: South Australia: Kangaroo Island, Cape Willoughby; 35°50’S, 138°08’E, 50 m; on sunny, exposed faces of granite outcrops overlooking the sea; Sep 2009, Kantvilas 367/09 (holotype HO; isotypes AD, CANB).
Additional specimens examined (paratypes):—AUSTRALIA: South Australia: Kangaroo Island, Cape Willoughby; 35°50’S, 138°08’E, 50 m; on sunny, exposed faces of granite outcrops overlooking the sea; Sep 2008, G. Kantvilas 332/08 (AD, HO).
Species littoralis, saxicola, thallo albido, crustaceo, usque ad 4.5 mm crasso, papillato vel nodulato vel plicato, acidum gyrophoricum continenti recognita; apothecia ignota, igitur huic generi cautione aliqua adsignamus.