Lecidea aptrootii M. Khan, A.N. Khalid, H. T. Lumbsch

Khan, Memoona, Khalid, Abdul Nasir & Lumbsch, H. Thorsten, 2018, A new species of Lecidea (Lecanorales, Ascomycota) from Pakistan, MycoKeys 38, pp. 25-34 : 27-31

Lecidea aptrootii M. Khan, A.N. Khalid, H. T. Lumbsch sp. nov. Figures 3, 4

Type.

PAKISTAN. Khyber Pakhtunkhwa Province, Swat district, Gabin Jabba valley, 1600 m alt., 37.1706°N, 72.3711°E, 18 Aug 2016, AN Khalid, GB-1 (Holotype LAH-35505).

Diagnosis.

Saxicolous, thallus irregularly areolate, apothecia epruinose, lecideine with persistent margin, asci with tholus, I+ blue, ascospores simple, ellipsoid with average size of 8-10 × 4.5-5.5 µm.

Description.

Thallus crustose, irregularly areolate, subcontiguous; prothallus usually indistinct, black when present; areoles flat, up to 1.2 mm in diameter and 300 µm thick, uniformity in colour from centre to edge; surface rough, not shiny, greenish-grey to light brown; Cortex not clearly differentiated, up to 31.5 μm in thickness; medulla I-, medullary hyphae thin walled, compactly arranged, 2.4-3.2 µm in diameter; photobiont layer up to 63 µm thick, algal cells 12.8-14.4 µm; apothecia black, round to irregular in outline, up to 1.5 mm in diameter, lecideine, epruinose with slightly raised, black, thin and persistent margin, frequently present, disc black, flat to slightly convex, proper exciple thin, dark brown to black; epihymenium light brown to dark brown, 8-16 µm; hymenium hyaline to olivaceous brown, (60)-70-98 µm tall; subhymenium light brown to dark brown, Hypothecium darkly pigmented throughout, Asci clavate with distinct tholus, the tip I+ blue, 8-spored, 50-68 × 12.30-16.70 µm; Ascospores simple, ellipsoid, (7)8-10(11) × (4)4.5-5.5(6) µm; paraphyses branched and net-like, 1.6-2.4 µm wide, not expanded at tips; vegetative propagules and conidiomata not seen.

Chemistry.

Thallus K-, KC+, C+ Red, P-, UV-. Gyrophoric acid, schizopeltic acid and 2'-O-methylperlatolic acid were detected with HPTLC.

Distribution and ecology.

The species is so far only known from two collections in the Swat district in Pakistan, where the species occurs on exposed siliceous rocks between 1600 and 1900 m altitude.

Etymology.

The epithet " aptrootii " refers to the lichenologist André Aptroot who has contributed to the knowledge of lichen diversity in Pakistan (e.g. Aptroot and Iqbal 2012) and has indicated to the first author that the material from Pakistan might represent an undescribed species.

Notes.

Lecidea aptrootii belongs to Lecidea sensu stricto ( Hertel 2006). The new species is a member of Lecidea subgen. Lecidea , according to the generic sub-classification as suggested by Rambold (1989). In the field, it looks like L. fuscoatra with an areolate thallus and black apothecia. A microscopic study revealed it differs from that species in having smaller ascospores. Another similar species in the complex is L. grisella , which, however, is readily distinguished by having a rimose rather than areolate thallus ( Aptroot and Van Herk 2007). Recently, Lecidea grisella has been reported from China, which might belong to L. aptrootii and has ascospores 8-12(13) µm in length ( Zhao et al. 2017) that overlap with an average spore length for L. aptrootii i.e. 8-10 µm. Additional studies are necessary to determine whether the Chinese material belongs to L. aptrootii or represents an additional lineage in this complex. Molecular data in Lecidea are helpful to interpret morphological features previously considered as intraspecific variation (Schmull 2011).

The areoles of L. fuscoatra have a differentiated black or grey margin, in contrast to the black cortex, whereas in L. aptrootii , the margins of areoles are concolorous with the areoles. This is a common feature of L. aptrootii and the recently described L. uniformis from North America ( McCune et al. 2017). However, the two species differ in the branching of paraphyses and presence of tholus in the asci. Further, molecular data support that they represent distinct lineages (Figs 1-2).

In addition, L. oreophila K. Knudsen & Kocourk. with irregularly areolate thallus, light to dark grey upper surface and epruinose apothecia, might be confused with L. aptrootii but the former has apothecia that are usually higher than areoles and rarely branched paraphyses with expanded apices up to 5 µm ( Knudsen and Kocourková 2014).

Molecular analyses of ITS and two ribosomal loci (ITS & nuLSU) dataset (605 and 1433 unambiguously aligned positions in ITS and two loci dataset, respectively) support the fact that the Pakistan collections are phylogenetically distinct from the morphologically similar L. fuscoatra and L. uniformis (Figs 1-2). In fact, the morphologically different L. grisella forms a well-supported sister-group relationship with L. aptrootii .

Additional specimen examined.

Pakistan, Khyber Pakhtunkhwa province, Swat district, Malam Jabba valley, 1900 m alt., on rock, 20 Aug 2016, AN Khalid, MJ-3 (LAH-35506).