Herteliana australis Fryday
Bibliotheca Lichenologica 88: 131. 2004.
Thallus widespreading, thin, 0.05-0.07 mm thick, creamy white, cracked-areolate, surface scurfy without a clearly defined cortex, prothallus absent. Photobiont chlorococcoid, cells globose 8-11µm diam.
Apothecia abundant, concave, round to slightly angular, 0.2-0.25 mm across, mostly translucent pale- to red-brown, occasionally becoming darker, remaining immersed in the thallus. Excipulum thin and poorly developed, completely hyaline. Hypothecium hyaline, thin, 10-20 µm, composed of randomly orientated hyphae. Hymenium hyaline, I+ blue, 150-170 µm thick; epihymenial zone c. 30-40 µm thick, orange to pale brown (K—, N—). Paraphyses sparingly branched and anastomosing, slender 1.5-2.0 µm wide, septate, cells 10-15 µm long, apices scarcely swollen and unpigmented. Asci cylindrical to slightly clavate, c. 60-80 x 17-20 µm, Bacidia-type. Ascospores hyaline, simple, (13-)15-17(-18) x 7-8(-8.5) µm, with attenuated apices.
Conidiomata not observed.
Chemistry: C—, KC—, K+ yellow, PD—, UV—. Atranorin only detected by TLC.
Herteliana australis is known from only the type locality on Campbell Island where it is associated with an unidentified species of Verrucaria
Notes: The genus Herteliana was proposed for the western European, maritime species H. taylorii (Salwey) P. James (Hawksworth et al. 1980). More recently Laundon (2005) showed that the correct name for H. taylorii was H. gagei (Sm.) J.R. Laundon.
The genus was considered to be monospecific until the north western North American species Bacidia alaskensis Nyl. was transferred there as H. alaskensis (Nyl.) Ekman (Ekman 1996). With the addition of a third species the genus now has a remarkably disjunct distribution; NW Europe, NW North America, and subantarctic New Zealand. However, all three species occur on siliceous, maritime rocks in areas with a highly oceanic climate.
The thallus of Herteliana gagei is reported as containing atranorin, confluentic acid and two unknown substances (Hawksworth 1992). Thin-layer chromatography confirmed the presence of confluentic acid and atranorin and revealed that the two unknown substances were 2’-O-methylperlatolic acid and 2’-O-methylmicrophyllinic acid, both constituents of the confluentic acid chemosyndrome (Gowan 1989). The single specimen of Herteliana australis contained only atranorin, although there were faint signs of spots at Rf classes 3-4 in all three plates. Herteliana alaskensis lacked both atranorin and the confluentic acid chemosyndrome, although one specimen (Brodo 26943) contained an additional unidentified substance (Rf classes 6, 8, 7-8) that appeared as a pastel-pinkish-tan-beige spot, fluorescing and faintly purple-grey in daylight after developing, and was possibly a triterpenoid. This substance was also present in at least one specimen of H. gagei (Coppins 16456), and probably also present in the other specimen of H. gagei, and at least one other specimen of H. alaskensis (Brodo 13980).
Hawksworth (1992) reported the ascospores of H. gagei as measuring (16-)18-22(-25) x 8-10(-11) µm but an examination of 24 ascospores from three collections of H. gagei from the western British Isles (Coppins 2747, 16322, 16456), revealed them to be significantly smaller (12.0-)14.75 ±1.63(-19.0) x (5.5-)6.5 ±0.61(-8.0) µm), which is in good agreement with the dimensions of the ascospores of H. australis.
Herteliana australis appears to be closely related to H. gagei. It has the same pale grey, glaucous thallus that contains atranorin, and has simple ascospores. By comparison, the thallus of H. alaskensis is a darker brown, lacks atranorin and the confluentic acid chemosyndrome, and has 3-septate ascospores. Herteliana australis differs from H. gagei in having numerous, innate apothecia and a thallus lacking confluentic acid. However, species that have sessile apothecia when they occur at temperate latitudes often have innate apothecia in the subantarctic (cf. Rimularia psephota below). The single collection of H. australis also lacks pycnidia, which are a conspicuous character of H. gagei. It is possible, therefore, that only one species is involved but, given the geographical separation of the two populations, it seems reasonable to recognise the Campbell Island specimen at specific rank.
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