Xanthoparmelia pedregalensis Barcenas-Pena , Lumbsch & Leavitt

Barcenas-Pena, Alejandrina, Leavitt, Steven D., Huang, Jen-Pan, Grewe, Felix & Lumbsch, H. Thorsten, 2018, Phylogenetic study and taxonomic revision of the Xanthoparmeliamexicana group, including the description of a new species (Parmeliaceae, Ascomycota), MycoKeys 40, pp. 13-28 : 13

Xanthoparmelia pedregalensis Barcenas-Pena, Lumbsch & Leavitt sp. nov. Figs 2C and D

Type.

MEXICO. Ciudad de México: Coyoacán, Pedregal de San Angel, 19°19'8.3"N, 99°11'25.93"W, 2321 m elev., xerophytic scrub, on rocks, November, 2017, Ruiz Cazares 1553 (MEXU-holotype), same locality and date Ruiz Cazares 1559 (MEXU-paratype).

Diagnosis.

Thallus moderately adnate to adnate, imbricate, upper surface yellow-green, lower surface tan-brown, abundant isidia subglobose to cylindrical, simple to branched and medulla containing salazinic and norstictic acids as major compounds and an unknown substance. Differing from the phenotypically similar X. mexicana by nucleotide position characters in the ITS sequence as shown in Table 2.

Etymology.

The taxon name is based on its occurrence in the Pedregal de San Angel region of Mexico.

Description.

Thallus foliose, moderately adnate to adnate, 2-7 cm in diam., irregularly lobate; lobes subirregular, elongate, plane to subconvex, 1.5-3 mm wide, not lobulate; apices subrotund, smooth, eciliate. Upper surface yellow-green, smooth, shiny, epruinose and emaculate, densely isidiate; isidia initially subglobose, becoming cylindrical to coralloid branched with age, 0.1-0.2 mm in diam., 0.1-0.9 mm tall; tips syncorticate, brown to dark brown, sometimes weakly erumpent; soralia and pustulae absent. Medulla white, with continuous algal layer. Lower surface tan to brown, plane, moderately rhizinate; rhizines pale to dark brown, simple, 0.5-0.9 mm long. Apothecia rare, sessile, 1-2 mm wide, laminal on thallus; disc cinnamon-brown to dark brown; margin smooth, pruina absent; asci: clavate, 8-spored; ascospores hyaline, simple, ellipsoid, 9-10 × 4-5 µm. Pycnidia rare, immersed conidia bifusiform, 5-7 × 1 µm.

Secondary metabolites.

Upper cortex K–, C–, KC–, P–; medulla K+ yellow then dark red, KC–, C–, P+ yellow-orange. Upper cortex with usnic acid (major); medulla with salazinic (major) and norstictic acids (submajor) and an unknown substance (minor) (Rf 28-30, brown in daylight after heating, UV brown-dark, yellow halo after heating).

Distribution and ecology.

The new species was found in xerophytic scrub vegetation, in Pedregal de San Angel south of Mexico City, growing on volcanic rocks. It is currently known only from the type locality.

Notes.

Xanthoparmelia pedregalensis is morphological and chemically similar to X. mexicana. However, the latter has more contiguous lobes and is less isidiate than X. pedregalensis . In addition X. mexicana has salazinic (major) and consalazinic acid (minor) and usually norstictic and protocetraric acids (trace) in the medulla, whereas X. pedregalensis contains salazinic (major) and norstictic acids (submajor) and an unknown substance. Distinguishing the two species is supported by molecular data.

Additional specimens examined.

Mexico. Ciudad de México: Coyoacán, Pedregal de San Angel, 19°19'8.3"N, 99°11'25.93"W, 2321 m elev., xerophytic scrub, on rocks, November, 2017, Ruiz Cazares 1552 (MEXU); 19°19'15.19"N, 99°11'15.22"W, 2311 m, Ruiz Cazares 1555, 1557 (F).