Verrucaria mundula P.M. McCarthy (Verrucariaceae, Ascomycota) – a new record for the Northern Hemisphere Carlos Pérez Valcárcel1, M. Eugenia López de Silanes2,3, and Graciela Paz-Bermúdez2 1 I.E.S. Adormideras, Juan Sebastián Elcano 28 A Coruña, España; 2 E.U.E.T. Forestal, Campus A Xunqueira, Universidade de Vigo, 36005 Pontevedra, Spain ABSTRACT. Verrucaria mundula P.M. McCarthy var. mundula is recorded for the first time for the Northern Hemisphere. Differences between Iberian specimens and the Australian type material are indicated, and the species is compared to other freshwater Verrucaria species found in Europe. KEYWORDS. Freshwater lichens, saxicolous, Iberian Peninsula. ¤ In the continental waters of Europe, lichens that withstand immersion have, in general, little studied. Significant treatments include those by Zschacke (1927, 1933–34), Wirth (1972), Keller (2000), Thüs (2002), and Thüs and Schultz (2009) for Central Europe, by Swinscow (1968), Hawksworth (1989), Gilbert (1996), Gilbert and Giavarini (1997), and Orange (2004) for the British Isles and by Asta et al. (1973), Ménard (1997), and Coste (2005) for France. The Iberian species were studied by Pereira (1992), Pereira and Llimona (1986–87, 1992) who focused on NE part of the Peninsula, or by Valcárcel et al. (1999) and Valcárcel & Carballal (2002) that dealt with the taxa occurring in the NW. The genus Verrucaria is frequent in freshwater habitats; 11 aquatic species belonging to this genus sensu lato have so far been collected in the Iberian Peninsula, namely Verrucaria aethiobola, V. aquatilis, V. elaeomelaena, V. funckii, V. hydrela, V. latebrosa, V. margacea, V. pachyderma, V. praetermissa, V. rheitrophila (Hydropunctaria rheitrophila by Gueidan 3 Corresponding autor e-mail: esilanes@uvigo.es DOI: 10.1639/0007-2745-113.2.267 The Bryologist 113(2), pp. 267–271 ¤ ¤ et al. 2009) and V. submersella. All of them are widespread throughout Europe. Most of the authors cited above regarded ascospore size as an important character to distinguish these species. To date, species in Europe with the smallest ascospores (less than 15 mm) include, in freshwater habitats, V. aquatilis, V. madida, V. rheitrophila and V. scabra. During work for the ‘‘Flora liquenológica Ibérica’’ project, the first author sampled many freshwater sites in all parts of the Iberian Peninsula. An additional species with small ascospores was collected in seven Spanish provinces; it is reported here as V. mundula McCarthy, the first record of this species from the Northern Hemisphere. MATERIAL AND METHODS Specimens in SANT (recently collected material of Verrucaria mundula, and comparative material of other species) and MEL were studied. Microscopical measurements were made on hand-cut sections, which were mounted in water or KOH. An optical microscope was used to study samples by bright field, dark field or phase contrast. Dark field was considered a suitable method to 0007-2745/10/$0.65/0 268 The Bryologist 113(2): 2010 Figure 1. Verrucaria mundula: A. vertical section of perithecium; B. asci and subcylindrical ascospores. C. V. rheitrophila, vertical section of thallus with carbonaceous spots. D. V. aquatilis vertical section of perithecium. Scale bars: A, B, D 5 10 mm and C 5 100 mm. photograph and observe involucrellum growth, while phase contrast proved useful for observation of asci, ascospores, excipulum and periphyses. THE SPECIES Verrucaria mundula P.M. McCarthy Fig. 1A&B TYPE: AUSTRALIA. NEW SOUTH WALES: Chichester State Forest, 19 km W of Stratford, Karuah R., by a ford on the Karuah Valley Road, off Wards River-Berrico Trig. Road, on moderately exposed aquatic slate, 9 Feb 1991, P.M. McCarthy 517 (MEL 1055304 - holotype!). Description of specimens from Spain. Thallus, crust-like, epilithic, subgelatinous, light to dark brown, sometimes almost black, smooth, 24.5–60 (–80) mm thick, ecorticate. Most of the specimens with abundant colorless crystals on the thallus of substratum. Photobiont green, 5–7 mm diam.; cyanobacteria often present in addition. Perithecia black, 0.14–0.18 mm in diameter, solitary, scattered, hemispheric, varying from half-immersed in the thallus to more or less superficial, covered by a thin layer of thallus or naked. Excipulum colourless. Involucrellum dark, dark brown in thin section, 25– 40 mm thick, contiguous with the exciple, extending up to two-thirds of the distance from apex to base of the perithecium. Hymenial gel I+ brown-orange. Paraphyses absent. Asci fissitunicate, clavate, (25–) 35–40(–50) 3 12–15 mm. Ascospores simple, colorless, narrowly ellipsoid to subcylindrical, 7.5– 12.5(–14) 3 4–6(–7.5) mm (45 measured). Ecology. On granite and schist rocks in river banks, from 0 to 30 cm above minimum water level, thus totally submerged for most or all of the year. It belongs to the Submerged to the Fluvial mesic zone of Gilbert (1996). It is always found in shady sites, and grows on surfaces of various inclinations. This species has been found accompanied only by Verrucaria aquatilis Mudd and also sometimes by a poorly developed lichen material, belonging in Verrucaria. Observations. The specimens from the Iberian Peninsula coincide with those described by McCarthy (1995) to a great extent, although some of our specimens have a thicker thallus, but in any case correspond to the V. mundula var. deminuta also described by McCarthy (1995) characterized by smaller asci (28–35 3 10–15 mm) and broadly ellipsoid or subglobose ascospores (6–)8.5(–10.5) 3 (4.5–)5.5(–6.5) mm. All the Iberian Peninsula samples are light to dark brown in color with a smooth Valcárcel et al.: Verrucaria mundula new to Northern Hemisphere 269 Table 1. Differences between the holotype material of Verrucaria mundula and the Iberian specimens. Verrucaria mundula Thallus Perithecium Excipulum Involucrellum Ascospores Type material Iberian Peninsula Green to greenish black (15–)20–30(–40) mm thick Not covered by a thallus layer 0.12–0.18(–0.2) mm diam. Colorless to light brown 25–35 mm thick (8.5–)11(–14.5) 3 (3 .5–)5(–7.5) mm Light to dark brown 24.5–60(–80) mm thick Covered or not by a fine thallus layer 0.14–0.18 mm diam. Colorless 25–40 mm thick 7.5–12.5(–14) 3 4–6(–7.5) mm thallus surface, whereas the Australian specimens are medium green to greenish black and some of them have a sparingly rimose thallus. Some perithecia are covered by a fine thallus layer, a feature that is not seen in the type material (Table 1). However, we do not believe that these minor differences justify the description of the Iberian specimens as a new species. The ecology of the specimens of both hemispheres is similar as McCarthy (1995) indicates that this is a saxicolous, aquatic or semi-aquatic taxon that grows in shaded or very shaded places on schists, slate, sandstone, basalt and rhyolites. The same can be said of the specimens from the Iberian Peninsula, but they are located only on acid rocks. Only four species of Verrucaria s.l. with ascospores less than 15 mm long are known from freshwater habitats in Europe; these are readily distinguishable from V. mundula (Table 2). Verrucaria aquatilis differs in the black thallus, larger perithecia and more immersed in the thallus, involucrellum diverging from the excipulum below (Fig. 1D), and smaller, broadly ellipsoid ascospores. Verrucaria madida Orange differs in the consistently dark green-coloured thallus, with green pigment in the cortex, larger perithecia, and in the asci with 4 (–5) ascospores are apparently unique in the genus Verrucaria s.l. (Orange 2004). Verrucaria rheitrophila Zsch. (5Hydropunctaria rheitrophila (Zsch.) Keller, Gueidan & Thüs) is distinguished by its greenish thallus (pigment in the cortex, if present, is brown) with carbonaceous spots (Fig. 1C), typical of the genus Hydropunctaria (Gueidan et al. 2009), which are only visible microscopically at times, but usually present in section, by its irregular involucrellum that Table 2. Differences between Verrucaria mundula and similar European species. V. aquatilis Thallus Perithecium Involucrellum Ascospores V. madida V. mundula Black without Grey green to dark Light to dark brown without carbonaceous spots green without carbonaceous carbonaceous spots spots 36–50 (–76) mm thick 40–60 mm thick 24.5–60(–80) mm thick Immersed to 2/3 Superficial 1/3 immersed to immersed superficial 0.15–0.35 mm diam. 0.2–0.42 mm diam 0.14–0.18 mm diam Contiguous with Contiguous with Contiguous with excipulum and excipulum and excipulum, not spreading at the spreading at the spreading at the base base base Subspherical (8/ascus) Ellipsoid (4/ascus) Subcylindrical (8/ascus) (9–)10.5–13.5(–15) 7.5–12.5(–14) 3 (5–)10(–12) 3 3 6–7(–7.5) mm 4–6(–7.5) mm 4–6(–8.5) mm V. rheitrophila V. scabra Green to greenish black with carbonaceous spots 54–142 mm thick Greenish to blackish with carbonaceous spots Immersed (110–)120(–140) mm thick Immersed 0.12–0.3 mm diam 0.3–0.65 mm diam Only around the Contiguous with ostiole excipulum and spreading at the base Ellipsoid (8/ascus) Subcylindrical (8/ascus) 8.5–12(–15) 3 (9.7–)14.2(–15) 3 5–10 mm (5–)7.2 (–9.4) mm 270 The Bryologist 113(2): 2010 generally grows only around the ostiole and by the more broadly ellipsoid ascospores. Verrucaria scabra Vzda (Hydropunctaria scabra (Vzda) Keller, Gueidan & Thüs), has a thicker thallus with internal carbonaceous spots and a dark basal layer; the perithecia immersed in the thallus and much broader. It is likely that V. mundula has been overlooked previously in the Iberian Peninsula, due to its thin thallus, small perithecia, and occurrence in shady, often submerged habitats. It has previously been recorded from Australia and the South Pacific (McCarthy 1995, 2000). Selected specimens examined of V. mundula P.M. McCarthy var. mundula. AUSTRALIA. NEW SOUTH WALES: Eden District, Yurammie State Forest, Chalkhill, Rats Valley Road, off Chalkshills Road, 11 km WNW of Pambula, 55HGV4618713669, on aquatic shale, [?shaded], 1991, P. M. McCarthy (MEL 1055260); 13 km WNW of Kiama, Minnamurra Falls Park, Minnamurra River, 56HKE3534790651, on deeply shaded semi-aquatic sandstone, P.M. McCarthy 488 (MEL 1055275); Chichester State Forest, Tributary of Karuah River, 1.5 km SE of Red Cedar Creek, by Karuah Valley Road, off Wards RiverBerrico Trig. Road, 56HLK8269841560, on deeply shaded aquatic basalt, 1991, P.M. McCarhy 537 (MEL 1055324). QUEENSLAND: S of Ingham, Mount Spec National Park, Little Crystal Creek under bridge on Paluma Road, 55KDU2261597141, on aquatic and semi-aquatic basalt, 1993, P.M. McCarthy 809 (MEL 1057463). TASMANIA: 4 Km E of Little Swanport, Little Swanport River, on semi-aquatic dolerite, 1993, P.M. McCarthy (MEL 2280718). SPAIN. CORUÑA: Vimianzo, Calo, Rı́o Grande, on granite, 120 m, 1999, C. Pérez Valcárcel (SANT 11326). HUELVA: Sierra de Aracena, Alájar, Rı́o Alájar, on schist, 500 m, 2006, C. Pérez Valcárcel (SANT 11327). LUGO: Rábade, Rı́o Miño, on schist, 440 m, 1999, C. Pérez Valcárcel (SANT 11628). OURENSE: Barco de Valdeorras, Entoma, Rı́o Galir, on schist, 360 m, 2000, C. Pérez Valcárcel (SANT 11329); Barco de Valdeorras, Xagoaza, Rı́o Mariñán, on schist, 460 m, 2000, C. Pérez Valcárcel (SANT 11330). PONTEVEDRA: A Golada, Seixo, Rı́o Ulla, on granite, 300 m, 2000, C. Pérez Valcárcel (SANT 11331). ZAMORA: Parque Natural de Sanabria, Sotillo de Sanabria, Rı́o Truchas, on granite, 1000 m, 2005, C. Pérez Valcárcel (SANT 11332). ACKNOWLEDGMENTS This study has been financed by the ‘‘Flora liquenologica Ibérica’’ project DGI CGL2004-04795-C04-03. The authors are most grateful to the curators at the SANT and MEL herbaria for the material loaned. LITERATURE CITED Aptroot, A. & M. R. D. Seaward. 2003. Freshwater lichens. Fungal Diversity Research Series 10: 101–110. Asta, J., G. Clauzade & C. Roux. 1973. Étude de quelques groupements lichéniques saxicoles-calcicoles du parc national de la Vanoise. Travaux Scientifiques du Parc National de la Vanoise 3: 73–104. Coste, C. 2005. 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