Introduction
The genus Xenolecia was erected by Hertel (Reference Hertel1984) for the single species Lecidea spadicomma Nyl. which, at that time, was known only from the type collection made by R.O. Cunningham from Isla Wellington (XII Región de Magallanes y de la Antárctica, Chile) in 1868. Hertel (op. cit.) placed the genus in the Porpidiaceae Hertel & Hafellner (now included in Lecideaceae Chevall.) on account of its Porpidia-type asci and separated it from other genera in that family by a combination of innate, immarginate apothecia and filiform conidia (Hertel op. cit., Fryday & Hertel Reference Fryday and Hertel2014). Xenolecia spadicomma has not been reported since but investigation of the rich material from southern South America, collected by Henry Imshaug and co-workers in 1968–71 (Fryday & Prather Reference Fryday and Prather2001) and housed in the herbarium of Michigan State University (MSC), revealed several collections of this species from the Falkland Islands (under the in sched. name “Lecanora falklandica Imsh.”). Subsequent fieldwork by the authors on the Falkland Islands and in northern Patagonia (X Región de Los Lagos, Chile) has further increased the known range of this species, which appears to be locally common, and permits a more detailed description than that provided by either Nylander (Crombie Reference Crombie1876 [1877]) or Hertel (Reference Hertel1984).
Also in MSC were several collections (under the in sched. name “Aspicilia campbelliana Imsh.”) from Campbell Island that were clearly congeneric with the Falkland collections but differed in having much smaller ascospores and a different thalline chemistry. These collections are described here as a second species of Xenolecia.
Materials and Methods
Specimens collected by Henry Imshaug and co-workers held in MSC, and recent collections from the Falkland Islands and Chile collected by the authors, were studied using standard microscopy techniques and reagents. Ascospore dimensions are given as mean±1SD with extremes in parentheses. Chemical constituents were identified by thin-layer chromatography in solvent C (Orange et al. Reference Orange, James and White2001).
Descriptions of ascus type follow Hafellner (Reference Hafellner1984) and nomenclature for apothecial pigmentation follows Meyer & Printzen (Reference Meyer and Printzen2000).
The Species
Xenolecia cataractarum Fryday sp. nov.
MycoBank No.: MB 819759
Differs from Xenolecia spadicomma (Nyl.) Hertel in having much smaller apothecia and ascospores, a greenish pigment in the epihymenium, a non-amyloid medulla and in the production of norstictic acid.
Type: New Zealand, Campbell Island, around waterfalls in Dracophyllum scrub on south slope of Mt. Honey, above Southeast Harbour, 21 January 1970, H. A. Imshaug 47396 (MSC0195380—holotype; CHR, BM, HO, M—isotypes).
Fig. 1 Thallus and apothecia of Xenolecia species. A, X. cataractarum (Imshaug 47396—holotype). B & C, X. spadicomma; B, collection from the Falkland Islands (Imshaug 41459); C, holotype from Chile (in BM). Scales: A–C=1 mm. In colour online.
Fig. 2 Xenolecia cataractarum, sections through apothecia. Scales: A & B=100 µm. In colour online.
Fig. 3 Xenolecia asci. A, X. cataractarum, immature ascus (Imshaug 47396—holotype); B, X. spadicomma, mature ascus (Imshaug 41889). Scales: A & B=10 µm. In colour online.
Fig. 4 Xenolecia distribution. A, world; B, Falkland Islands; C, Chile. ●=X. spadicomma; ■=type of X. spadicomma; ▲=X. cataractarum.
Thallus creamy white, with a distinct, obscurely effigurate margin with a blue-black prothallus (Fig. 1A); medulla I−. Photobiont chlorococcoid, arranged in loosely defined vertical bundles; cells globose to slightly ovoid, sometimes irregularly shaped and angular (presumably disrupted), 5–7(–9) µm across.
Apothecia numerous, black, innate with a concave disc, 0·2–0·5 mm diam.; proper margin not apparent but disc often surrounded by a blue-grey border, 0·05 mm wide, that is formed by the thallus cortex overreaching the epihymenium. Proper exciple poorly developed, annular, 10–15 µm wide, very dilute orange-brown, structure unclear but apparently little differentiated from the hymenium (Fig. 2A). Hypothecium dilute brown to dark brown, upper part composed of vertically arranged hyphae, lower part ±cellular, extending into the thallus for up to 160 µm. Hymenium c. 220–250 µm tall; paraphyses slender (1 µm wide), sparingly branched and anastomosing, not or only slightly swollen at the apex (Fig. 2B); epihymenium olivaceous (N+ red, K± brown; probably Cinereorufa-green and Arnoldiana-brown). Asci cylindrical-clavate, 50–60×15–18 µm, outer wall I+ blue, immature asci initially with a distinct I+ blue cap, occasionally with a less distinct ring structure extending down into the tholus (Fig. 3A), mature asci Porpidia-type, similar to that of X. spadicomma (Fig. 3B); ascospores simple, hyaline, with a thin gelatinous sheath (halonate), broadly ellipsoid, (12–)14·84±1·65(–18)×(6–)6·91±1·02(–9)µm; l/w ratio 1·67–3·00, mean=2·20, (n=16).
Conidiomata pycnidia, black, immersed, abundant at the thallus edge when two thalli meet; conidia hyaline, filiform, 20–25×1 µm (n=10).
Chemistry. K+ red, C−, KC−, PD+ yellow, UV+ dull white; norstictic acid by TLC.
Etymology. Named after the habitat of the only collection (Latin: ‘cataractarum’=of waterfalls).
Distribution and Ecology. The new species is known only from the type locality on Mt. Honey, Campbell Island, New Zealand (Fig. 4A), where it is apparently quite frequent on siliceous rocks near a waterfall because Imshaug made four separate collections, along with several duplicates.
Additional specimens examined. New Zealand: Campbell Island: around waterfalls in Dracophyllum scrub on south slope of Mt. Honey, above Southeast Harbour, 1970, Imshaug 47386 (MSC0195381—topotype), 47395 (MSC0195382, BCRU, E, BG, HO, FH, GZU, H, OTA—topotypes), 47399 (MSC0195383—topotype).
Xenolecia spadicomma (Nyl.) Hertel
Beih. Nova Hedwigia 79: 440 (1984).
Basionym: Lecidea spadicomma Nyl., in Crombie, J. Linn. Soc. Bot. 15: 233 (1876); type: Chile, (XII Región de Magallanes y de la Antártica Chilena, Isla Wellington), Eden Harbour, in the bed of a stream, April 1868, R. O. Cunningham (BM!—holotype; BM!, E!, H —isotypes).
Fig. 5 Habitat of Xenolecia spadicomma (Patricia Luxton NNR, Chartres, East Falkland, Falkland Islands). Xenolecia spadicomma is the orange lichen just above the water line.
Fig. 6 Xenolecia spadicomma, comparison of ascospore dimensions of type specimens with other collections from NW Patagonia and the Falkland Islands. △=type collection; ●=NW Patagonia; ■=Falkland Islands.
Thallus thick, rimose-areolate, cream-brown to yellow-orange, sometimes mottled with alternating dark grey and orange parts; upper section composed of vertically orientated hyphae without an upper cortex but surface cells with a dilute brown pigmentation (Fig. 1B & C); medulla I+ violet. Photobiont chlorococcoid, 7–12 µm diam.
Apothecia 0·5–2·2 mm diam., numerous, ±regularly scattered, innate, rounded,±flat or occasionally concave; proper margin not evident; disc dark brown to black, paler brown when wet. Proper exciple annular, poorly developed, not reaching the thallus surface, dilute brown, 15–20 µm wide, composed of narrow septate hyphae. Hypothecium dark brown, 90–105 µm tall, often extending up to 350 µm into the thallus, composed of vertically arranged hyphae that merge with the hymenium, less well organized at base. Hymenium 180–200 µm tall; paraphyses slender, c. 1 µm thick, only slightly swollen at apex, branched and anastomosing; epihymenium 12–20 µm thick, pale brown (Arnoldiana-brown). Asci 70–60×20–25 µm, cylindrical-clavate, mature asci Porpidia-type (Fig. 3B; but cf. X. cataractarum for immature asci); ascospores simple, hyaline (15·4–)23·0 ±3·64 (–32·5)×(6·0–)10·7 ±2·15(–15·6) µm; l/w ratio 1·7–2·6, mean=2·20, (n=111).
Conidiomata pycnidia, usually present, dark brown to black, 0·05–0·10 mm diam., immersed in the thallus, most frequent along the thallus margin adjacent to other thalli; conidia hyaline, filiform, (18–)25–30×1 µm (n=10).
Chemistry. K−, C−, Pd−, UV+ dull white. Confluentic acid (major), 2’-O-methylmicrophyllinic acid (minor) by TLC.
Distribution and ecology. The distribution of X. spadicomma, with three widely separated localities from the Falkland Islands (where it is common) to northern Patagonia (Fig. 4), suggests that it is a widespread species in the area, although its absence from the extensive collections made from western Patagonia and Fuegia (Isla Grande and Isla de los Estados) by Imshaug and co-workers (Fryday & Prather Reference Fryday and Prather2001) is surprising.
Xenolecia spadicomma is primarily a species of semi-inundated streamside rocks (Fig. 5), although it has also been collected from mountain summits (Imshaug 41549) and in rainwater-collecting depressions in otherwise dry rocks (Fryday 11355).
Additional specimens examined. Chile: X Región, Los Lagos (northern Patagonia): Comau Fjord, Huinay, Rio Lloncochaigua, 42°22'03·7''S, 72°24'26·0''W, rapids 1 km upstream of junction with Rio Huinay, on large gneiss boulders, c. 2 m above low water level in partially shaded river bank, i 2014, Thüs (BM001088488); ibid., cascades of nameless streamlet below reservoir of hydroelectric power plant for Huinay Research Station, 42°22'58·39''S, 72°24'40·59''W, on large partly shaded boulder in splash water zone, i 2014, Thüs (BM001089604); ibid., National Park Llanquihue, Calbuco Volcano, S-slope, bridge of Sendero Alerce Andino over tributary to Rio Blanco, 1 km N of CONAF checkpoint, in splash water zone of shaded rapids on permanently wet volcanic (mafic) rock outcrops, 41°22'51·3''S, 72°38'39·3''W, i 2014, Thüs (BM001085888).—Falkland Islands (all in MSC): East Falkland: Mt. Usborne, valley SW of Mt. Usborne, 21F UC 7068 (51°43·240'S, 58°52·650'W), 200 ft. (61 m), along stream in Cortaderia-heath and sandstone outcrops, 1968, Imshaug 40177, 40190, 40195 (MSC0011043, MSC0011038, MSC0011039); Stanley, headwaters of Mullet Creek Stream, 1968, 21F VC 3270 (51°42·570'S, 57°58·820'W), 200 ft. (61 m), mosaic of Empetrum-heath and peat bogs, Imshaug 41438, 41459 (MSC0011044, MSC0011037); ibid., Mullet Creek Stream, below fiord, 21F VC 3270 (51°42·970'S, 57°58·570'W), 150 ft. (45·75 m), 1968, Imshaug 41464, 41484 (MSC0011040, MSC0011042); ibid., cliffs on rock dome at summit of Mt. Kent, 21F VC 2374 (51°42·550'S, 58°0·900'W), 1500 ft. (457·5 m), 1968, Imshaug 41549 (MSC0011041). Saunders Island: Rookery Cottage, −51·306687°, −60·098780°, 44 m, pebbles in Empetrum-heath, 2015, Fryday 11355 (MSC0195384). Weddell Island: Waterfall Valley, W of settlement, 21F TC 2842 (51°54·040'S, 60°56·820'W), 300–700 ft. (91·5–213·4 m), stream bed, 1968, Imshaug 41889 (MSC0011036); ibid., −51·901456°, −60·948128°, 190 m, sloping, semi-inundated rocks, 2015, Fryday 10855 (MSC0195385). West Falkland: Chartres, Patricia Luxton NNR, −51·724676°, −59·985162°, 13 m, sloping rock by river, inundation zone, 2015, Fryday 11001 (MSC0195386).
Discussion
All the collections of Xenolecia cataractarum were made over 45 years ago and consequently it was not possible to confirm its generic placement by molecular methods. However, although the two species described here differ in numerous characters (size of apothecia and ascospores, epihymenium pigmentation, thalline chemistry and medulla amyloidity), they are united by their general anatomical structure (slender, branched and anastomosing paraphyses, a strongly reduced proper exciple, Porpidia-type asci, a hypothecium composed of vertical hyphae that intergrades with the hymenium without an intervening subhymenium, and filiform conidia). They are also very similar in gross morphology, having a pale creamy orange thallus delimited by a black prothallus, with innate, immarginate apothecia and producing abundant pycnidia where adjacent thalli meet (Fig. 1A). Consequently, we are confident that the new species is congeneric with X. spadicomma. Paraporpidia Hertel and Stephanocyclos Hertel are two other Southern Hemisphere genera with Porpidia-type asci and filiform conidia but species of both these genera have a well-developed proper exciple. In Stephanocyclos the proper exciple is irregular and carbonaceous whereas Paraporpidia is further distinguished by the ascospores lacking a gelatinous sheath (Hertel Reference Hertel1984; Fryday & Hertel Reference Fryday and Hertel2014).
The olivaceous pigmentation present in the epihymenium of X. cataractarum is common in the porpidioid genera of the Lecidaceae, as well as many other genera of the Lecanoromycetidae, and was previously referred to by the first author as Macrocarpa-green (Fryday 2002, Reference Fryday2005). However, we now consider this coloration to be the result of at least two separate pigments, Cinereorufa-green and Arnoldiana-brown, which are also frequent in these genera. A chemical characterization of these coloured components, however, is still outstanding.
The variation in ascospore dimensions of X. spadicomma is large (Fig. 6, Table 1), and we considered the possibility that our collections represented a separate species distinct from X. spadicomma. Unfortunately, owing to issues associated with the small sample size of our data (holotype, 1 collection; NW Patagonia, 3 collections) the results of standard statistical tests would have been invalid. However, it can be seen from a plot of the ascospore dimensions (Fig. 6) that those of the type collection, although at the upper end of the range, fall within the limits of the other collections. Consequently, in the absence of molecular data and until further material from the vicinity of the type collection becomes available, we are including our collections in X. spadicomma.
Table 1 Dimensions of ascospores from different populations of X. spadicomma given as mean±standard deviation
The ascus structure of Xenolecia was described by Hertel (Reference Hertel1984) as Porpidia-type but we found that immature asci differ from that type as described by Hafellner (Reference Hafellner1984) and have some resemblance to the Lecidea-type (Hafellner Reference Hafellner1984). Both Lecidea- and Porpidia-type asci have a KI+ pale blue tholus but whereas the Lecidea-type have a small, darker staining cap, possibly with a small ring structure beneath it, the Porpidia-type lack a cap but have a distinct darker-staining ring structure for the full height of the tholus (Hafellner Reference Hafellner1984). Initially, asci of Xenolecia have only a well-defined, dark staining cap but an indistinct ring structure the full height of the tholus develops (Fig. 3A) and only mature asci are of the typical Porpidia-type (Fig. 3B). Xenolecia was placed in the Porpidiaceae by Hertel (Reference Hertel1984), which is now included in the Lecideaceae, but the combination of Porpidia-type asci, filiform conidia and the hymenium structure, lacking a subhymenium and with the paraphyses grading directly into the hypothecium composed of vertically orientated hyphae, is anomalous for that family and preliminary molecular data (T. Wheeler, pers. comm.) indicate a placement for the genus outside the core Lecideaceae.
The first author thanks the UK Government for funding (via the Darwin Initiative) to visit the Falkland Islands and collect lichens, and Falklands Conservation, in particular Dafydd Crabtree for logistical support. The second author thanks the team at Fundación San Ignacio del Huinay and in particular Vreni Häussermann and Günter Försterra for logistical support. Fieldwork in Chile was carried out under permit number 043/2013 granted by the Corporación Nacional Forestal (CONAF) for the project “Freshwater lichens of the Valdivian temperate rainforests”. We also thank Klara Scharnagl (East Lansing) for producing the graph in Fig. 6.
