Pyxine mexicana Kalb

Data Set Maintenance: Data set compiled (from Sonoran Desert Lichen Flora). Data set author(s): Bungartz F. (02-04-08). Data set to be published after submission; February 2002.

Nomenclature: Current taxonomic status: accepted. Taxonomic rank: species. Currently accepted name Pyxine mexicana Kalb. Pyxine. Physciaceae Zahlbr. (1898); Lecanorineae.

Type Information: Type: Pyxine mexicana Kalb; protologue: Similis P. coralligerae, sed differt medulla alba, marginibus
apotheciorum pruinosis et terpenis aliis.; type specimen label data: Mexico. Baja California Sur: Sierra La Laguna just above Rancho La
Victoria, oak forest, on Quercus devia; c. 1200m, 23°36'43" N,
109°54'43"W, 6. Jan 1998, leg.: T.H. Nash III 39585 (ASU -
holotype, hb. Kalb - isotype).

Taxonomic Literature: Nash III, T.H., Ryan, B.D., Gries, C. & Bungartz, F. (ed.)
(2002): Lichen Flora of the Greater Sonoran Desert Region. - Lichens
Unlimited, Tempe, page 439.

Biogeography: Mediterranean; montane. Continent: Northern America. Checklist records: Mexico and Sonoran Desert (probably a Sonoran endemic).

Ecology: Biotroph; lichenized; lignicolous or corticolous; episubstratic; growing sun-exposed or partially shaded; under conditions which are dry or moist; substrate non-calciferous.

Thallus: Foliose (firmly appressed), subdivided into main parts, lobed (firmly appressed); lobes horizontal; subconcave, usually plane, or subconvex; separate thallus parts.8-2 mm wide. Thallus Size and Differentiation: Up to 5 cm in diameter. Thallus Outline: Orbicular. Upper Surface: Grey, almost white, or grey-brown; pruinose; pruina scarce or abundant (punctiform, rarely confluent); pseudocyphellate; pseudocyphellae sometimes reticulate, usually peripheral or laminal (later spreading laminal accross the surface), submarginal; eciliate; without hairs; isidiate (polysidiangia); isidia laminal (later), submarginal; with isidiomorphs (polysidiangia according to Kalb); sorediate (bursting from polysidiangia); soralia laminal (later) or subperipheral, linear, isidiate (developing from polysidiangia); not blastidiate; not schizidiate; not lobulate. Lower Surface: Present, black or grey, black in the centre, grey (towards the lobe tips) along the margin, firmly attached attached; attached by holdfasts (true rhizines); rhizinate; rhizines black, branched, sparsely furcate; not sorediate; not tomentose.

Upper Cortex: Present; outer cortical layer paraplectenchymatous (formed by anticlinal hyphae); inner cortical layer prosoplectenchymatous or scleroplectenchymatous (formed by periclinal hyphae). Lower Cortex: Present.

Reproduction Strategy: Rarely with sexual (and possible asexual) stages. Ascocarps: Apothecioid (obscurascens-type), orbicular, forming all across the thallus surface, soon sessile or substipitate (on a distinct internal stipe), sparse, .6-2 mm in diam.. Margin: Lecideine/biatorine (when margin excluded), smooth (pruinose), excluded, distinct; not sorediate; not isidiate; not ciliate; not hirsute. Disk: Plane; black; epruinose. Exciple: Carbonized (when margin excluded). Epithecium: Apical cells brownish blue (not brown: bluish black), cell pigment reacting with 10% KOH (K+ purple). Hypothecium: White (entire stipe unpigmented).

Asci: Dehiscence lecanoralean.

Ascospores: Dirinaria-type, c. 8 per ascus, spores 8 per ascus, ellipsoid, 17-21 µm long, 5.5-7 µm wide; septa present; transversally septate; 1-transversally septate; wall apically thickened, subapically not thickened, thickened at the septum, becoming pigmented, dark brown or middle brown (at maturity).

Conidiomata: Present.

Conidiophores: Vobis-type VI. Conidia: Bacilliform; 3-4 µm long; 1 µm wide.

Secondary Metabolites: Present; only in the upper part of the cortex, atranorin, metabolite(s) of unresolved identity: present (medulla with terpenes of characteistic array).

Spot Tests: Present reactions. Upper surface: K + deep yellow, C –, KC –, PD + yellow; cortex: KC + deep yellow (upper cortex), – or + deep yellow (upper cortex), PD + yellow (upper cortex); medulla: K – (stipe, upper and lower cortex); C – (stipe, upper and lower cortex), KC – (stipe, upper and lower cortex).

(report generated 13.Nov.2007)