Verrucaria alpicola Zschacke

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

Verrucaria alpicola Zschacke ( Figs. 3D–E )

Hedwigia 67: 75–76 (1927).

Type:— [ SWITZERLAND, Graubünden] Rhätische Alpen: Davos im Jakobstobel, 7.1916 Zschacke 4278 [B60 0081286] (lectotype, designated here, B!). — Syntypes: Davos , im Dorfbache , 2000 m. 07.10.1916, Zschacke 4818 [B60 0081287] (B!) ; Davos 496, Drusatscha-Bach ; 26-9-1916 [B60 0086932 p.p.] (B!); “D[avos?] 410, …. [illegible] ± 2000 m 4.9.1916 ” [B60 0086932 p.p.] (B!) ; [ ROMANIA], Siebenbürgen: Bulleabach unterhalb des Sees , 29.07.1910, Zschacke [B600047110] (B!), Rhetyezat ; 9.7.1912, Zschacke 2900 [B609 086931] (B!). — Epitype (designated here) : ITALY, Bolzano, Altopiano dello Sciliar c/o rif. Bolzano , in spring on calcareous rock, 2400 m, 19.07.2007, Nascimbene JN 2130 [BM001085415] (BM!), GenBank accession no KM243213 .

Prothallus absent. Thallus smooth, distinctly subgelatinous in specimens from shaded sites, usually cracked at least around the perithecia at exposed sites, ± subgelatinous, air filled spaces around hyphae usually not visible in anatomical sections; thallus colour light to usually dark (black-) brown or greyish, thin 15–43 μm, black basal layer rarely present, up to 30 μm high. Cortex with yellowish to black-brown pigment (absent in specimens from shaded localities). Photobiont cells 4.5–10 μm in diameter. Perithecia forming distinct projections 465–675 μm wide, covered by a thin thallus mantle, rarely the area surrounding the ostioles exposed, 9–36 perithecia in an area of 25 mm 2; involucrellum 17–38 μm thick, exciple 200–350 μm wide, with brown pigment reaching the bottom of the exciple in specimens from sun exposed sites, periphyses (15) 25–35 (43) μm, asci 83–100 × 20–33 μm, 8–spored, ascospores (19.2) 24.5– 28.6 –32.6 (43.50) × (9.6) 12.4– 14.3 –16.1 (18.9) μm, length/width ratio (1.5) 1.7– 2.0 –2.3 (3.6) [164/14], halonate perispore absent. Pycnidia not observed.

Habitat and distribution: This is a typically sub-aquatic species, which often occurs in the splash water zone of turbid stretches in streams, but it is also found at temporarily inundated sites in springs. It grows on hard calcareous and siliceous rocks in sunny to moderately shaded sites. Sequenced specimens were seen from high elevations in the Austrian, Swiss and Italian Alps, Wales and from Norway.

Typification: Verrucaria alpicola is a monophyletic species that is nested within V. elaeomelaena agg., but even within V. alpicola the genetic diversity is high and the description of further segregate taxa can be expected once more sequenced specimens become available. The morphological variation in the syntypes from Romania and Switzerland may represent different taxa and a lectotypification is required to stabilise the use of this name. We have chosen Zschacke 4278 (B 60 0081287) as lectotype for V. alpicola , because the material is well developed and Zschacke has left detailed annotations and measurements of internal structures for this specimen. The lectotype agrees morphologically with the sequenced specimen JN2130 which was collected in the Italian Alps at a similar elevation as the Swiss type locality.

Figures

FIGURE 3. A. Cross-section of a perithecium of Verrucaria submersella (syntype BM). B. Cross-section of a perithecium of Verrucaria elaeomelaena (isolectotype BM). C. Thallus of Verrucaria elaeomelaena (isolectotype BM). D. Thallus of Verrucaria alpicola (lectotype B). E. Cross-section of a perithecium of Verrucaria alpicola (lectotype B). Scale bar: A, B, E = 50 μm; C–D = 5 mm.