Verrucaria humida Orange, 2015

Schiavo, Lo, 2015, Revision of the Verrucaria elaeomelaena species complex and morphologically similar freshwater lichens (Verrucariaceae, Ascomycota), Phytotaxa 197 (3), pp. 161-185 : 178-181

Verrucaria humida Orange spec. nov. ( Figs. 4A–E )

MycoBank No: MB 809758

Thallus epilithicus, tenuissimus, laevis. Perithecia prominentia, 200–360 μm latae, nuda. Ascosporae (21–)22– 23.6 –25(–26) × 10– 10.9 – 11.5(–12.5) μm.

Type:— GERMANY. Baden-Württemberg, Schwarzwald, east of Altglashütten, north-west of Windgfällweiher - 47°51.35’N, 08°07.34’E, alt. 975 m, on wet stones in bed of streamlet in Picea abies forest, shaded, 15 September 2010, A. Orange 19370 (NMW [C.2010.001.133], holotype!), GenBank accession no KM243202.

Figs. 4 A–H . Prothallus not seen. Thallus very thin, c. 12–25 μm thick, smooth, continuous, grey-green or brown (at least the pale specimens green and translucent when fresh and wet). Perithecia prominent, black, forming conicalhemispherical to hemispherical projections 200–360 μm diameter, occasionally collapsed when dry, smooth or slightly roughened, ostiolar region inconspicuous, or ostiole visible as a pale dot or papilla c. 40 μm wide; thalline layer absent or present only at extreme base. Involucrellum thin (11–30 μm), appressed to exciple above, usually diverging at base, dark brown, K + darker brown, greyish brown, or dark green. Exciple 170–200 μm wide, colourless at sides and base. Periphysoids 17–26 μm long. Asci c. 58–80 × 20–35 μm, 8-spored. Ascospores oblong-ellipsoid, simple, colourless, without perispore, (20) 22– 23.4 –25(–26) × 10– 11.0 –12 (12.5) μm, length/width ratio (1.7) 2.0– 2.1 –2.3 (2.5). [36/5]. Pycnidia not seen.

Ecology and distribution. On stones in seepages and streamlets in woodland.Associated species include Verrucaria elaeomelaena s.l., V. funckii , and V. sublobulata . The stream at the type locality had a pH of 6.4 and conductivity 187 μS/cm, and the locality of Orange 19368 nearby had a pH of 7.3 and conductivity 200 μS/cm. So far known from Great Britain ( Wales), Norway, Germany (Schwarzwald) and Poland.

Notes. Important features for the recognition of this species include the small, prominent, naked perithecia, the medium-sized ascospores, a very thin, smooth, continuous thallus, and the habitat on wet rock. It differs markedly from the other taxa in the V. elaeomelaena group by the smaller, prominent perithecia without a thalline cover. It is likely to be confused with other, poorly known species with a thin thallus and small naked perithecia. It is recommended that for the time being, the identity of specimens referred to this species should be confirmed by sequencing.

This species was treated by Krzewicka (2012) under the name Verrucaria andesiatica .

Additional specimens examined. — NORWAY: Troms, Karlsøy kommune, Ringvassøya, east side of Glimvatnet - 69°50.15’N, 19°18.98’E, alt. 60 m, on stones in shaded streamlet in woodland, 9 July 2010, A. Orange 19318 (NMW [C.2012.002.111]). UNITED KINGDOM: Wales, V.C. 48, Merioneth, SE of Betws-y-coed, north side of Afon Conwy, 23/821.528, alt. 200 m, on stones in seepage in woodland, 26 April 2007, A. Orange 16783 (NMW [C.2007.001.385]). GERMANY: Baden-Württemberg, Schwarzwald, east of Altglashütten, north-west of Windgfällweiher, 47°51.278’N, 08°07.240’E, alt. 965 m, on stone in streamlet in Picea abies woodland, shaded, 15 September 2010, A. Orange 19368 (NMW [C.2010.001.132]). Schwarzwald, west of Hinterzarten, 47°54.78’N, 08°04.97’E, alt. 805 m, on wet stones in shallow ditch at side of track in forest, 23 August 2012, A. Orange 21178 (NMW [C.2012.002.165]). POLAND: Western Tatra Mountains, Dolina Chochołowska valley, Chochołowski Potok stream, alt. 1105 m, 16 July 2004, B. Krzewicka 2719a (KRAM).

Figures

FIGURE 4. Anatomy and habitus of Verrucaria humida. A. Thallus of specimen Orange 19370 (holotype, NMW), B. Thallus of specimen Orange 16783 (NMW). C–D. Cross-sections of perithecia of specimen Orange 19370 (holotype, NMW). E–F. Cross-sections of perithecia of specimen Orange 16785 (NMW). G. Cross-section of a perithecium of specimen Krzewicka 2719a (KRAM). H. Crosssection of a perithecium of specimen Orange 19318 (NMW). Scale bar: A–B = 1 mm; C–H = 100 μm.