Architrypethelium murisporum Luangsuphabool, Lumbsch & Sangvichien

Luangsuphabool, Theerapat, Lumbsch, H. Thorsten, Piapukiew, Jittra & Sangvichien, Ek, 2018, Architrypetheliummurisporum (Ascomycota, Trypetheliaceae), a remarkable new lichen species from Thailand challenging ascospore septation as an indicator of phylogenetic relationships, MycoKeys 34, pp. 25-34 : 25

Architrypethelium murisporum Luangsuphabool, Lumbsch & Sangvichien sp. nov. Figure 2

Type.

THAILAND. Ubon Ratchathani Province: Na Pho Klang, Khong Chiam District, 15°31'N, 105°35'E, ca. 130 m alt., dry evergreen forest, on tree bark, 27 November 2012, T. Luangsuphabool RAMK 031332 (holotype: RAMK).

Diagnosis.

Characterised within the genus by having small, hyaline and muriform ascospores.

Etymology.

The specific epithet refers to the muriform ascospore character of the new species.

Description.

Thallus crustose, corticate, thick, green to yellow-green, smooth to uneven, with cortex 40-125 μm thick, medulla 20-75 μm thick, prothallus black. Algae trentepohlioid, cells 18-65 μm wide. Ascomata perithecia, pyriform, black, 0.45-0.60 mm diam., erupent to prominent, fused into a pseudostroma, not covered by thallus. Ascoma wall carbonised, up to ca. 145 μm thick. Ostiole apical, black, not shared, with a white annulus surrounding the ostiolar region. Pseudostroma forming raised black lines, irregular in shape or forming a partial network on the thallus. Hamathecium hyaline, not inspersed with droplets or granules, consisting of branched and anastomosing paraphyses, 1.5-2.5 µm thick. Asci clavate to cylindrical, 150-200 × 32-50 µm. Ascospores 8 per ascus, hyaline, muriform with 6-9 transverse and 1-2 longitudinal septa per tier near centre of spore in optical section, narrowly ellipsoid, 35-50 × 13-15.5 μm. Pycnidia not observed.

Secondary chemistry.

Thallus UV–, K–, C–, KC–, PD–; pseudostroma UV–, K–, C–, KC–, PD–. TLC: no substances detected.

Distribution and ecology.

The new species was found in north-eastern Thailand, growing in a dry evergreen forest on tree bark. It is only known from the type locality.

Notes.

Architrypethelium murisporum is morphologically similar to Astrothelium keralense (Upreti & Ajay Singh) Aptroot & Lücking and A. variatum (Nyl.) Aptroot & Lücking in having hyaline, small and muriform ascospores, but differs in having ascomata fused into a pseudostroma and not covered by the thallus (ascomata solitary, covered by the thallus in A. keralense and ascomata covered by thallus except ostiole regions in A. variatum ), narrowly ellipsoid ascospores (fusiform in both Astrothelium spp.). Also the ascospore size (35-50 × 13-15.5 μm) differs from A. keralense (50-60 x 15-20 μm) and A. variatum (24-35 x 11-13 μm). The placement of the new species in Architrypethelium is supported by molecular evidence (Fig. 1), but it is unlikely to be confused with any of the currently accepted species in that genus due to the differences in ascospore size and septation ( Aptroot et al. 2008, Aptroot and Lücking 2016, Flakus et al. 2016, Lücking et al. 2016a). The new taxon has muriform and relatively small ascospores (ca. 50 µm, long) (Fig. 2), whereas other Architrypethelium species have transversely septate ascospores (3-5 septate), that are longer than 90 µm ( Aptroot 1991, Aptroot et al. 2008, Aptroot and Lücking 2016, Flakus et al. 2016, Lücking et al. 2016a).