Cladonia pyxidata

Yánez-Ayabaca, A., Ahti, T. & Bungartz, F., 2013, The Family Cladoniaceae (Lecanorales) in the Galapagos Islands, Phytotaxa 129 (1), pp. 1-33 : 23-24

Cladonia pyxidata (L.) Hoffm. (1796: 121)

( Fig. 5f )

Primary thallus persistent, of ascending squamules; esorediate, epruinose; podetia common, grayish green to brown, short; 0.4–1 cm tall; with broad scyphi shaped like a trumpet, i.e., with a wide rim tapering to a thin stalk; cups mostly simple but very rarely proliferating from their margin, forming additional scyphi; surface corticate at the base of the scyphi, becoming aereolate to granulose, but not sorediate, typically with large, corticated granules inside the cup; rarely with schizidia; esorediate and always lacking microsquamules; pycnidia with hyaline jelly; apothecia with brown jelly.

Spot tests and chemistry: P+ orange red, K−, C−, KC−, UV−; fumarprotocetraric acid.

Distribution and ecology: New to Ecuador and Galapagos; found on Isabela, and Santiago Island. Although C. pyxidata in widespread in the world, it was not reported from most of the Andes by Ahti (2000), although the very similar calciphilous species C. pocillum was found in those areas. Among the “pixie cup lichens” of Galapagos, C. pyxidata is more common than C. grayi , but much rarer than the common C. chlorophaea and the very common C. subsquamosa . Unlike the other superficially similar species, collections of C. pyxidata are quite often also found at the lower altitudes of the dry and transition zone and the species thus appears not as restricted to humid habitat.

Notes: Several species of Cladonia with broadly cup-shaped podetia can be distinguished in Galapagos; C. chlorophaea , C. subsquamosa , C. grayi and C. pyxidata . They differ by the shape of their cups, surface cortication, development of propagules and chemistry.

Cladonia pyxidata is the only species that does not form soredia , but instead only produces relatively large, corticate granules. It forms trumpet-shaped cups with a wide rim and more abruptly tapering stalk. Cups formed by C. chlorophaea are not as broad, generally more cone-shaped and thus gradually tapering towards its base. This species forms farinose soredia of more or less uniform size. Cups of C. subsquamosa are very similar but the species produces microsquamules, granules and soredia, all rather heterogeneous in size. When well developed specimens of C. subsquamosa are abundantly proliferating forming tiers of cups. Such repeated proliferations are not common in the other species but can occasionally be observed in C. grayi , which, however, is reliably distinguished by its conspicuous UV+ whitish blue reaction due to the presence of grayanic acid, a secondary metabolite absent from all other species.

Selected specimens examined: ECUADOR. GALAPAGOS: Isabela Island, Volcán Alcedo, outer SEexposed slope, ca. 500 m below the crater rim, 0°27’13”S, 91°5’46”W, 1035 m, humid zone, on bark, 3 June 2006, Aptroot, A. 64846 ( CDS 31422) . Santiago Island, summit of Cerro Gavilán , inner N- and NE-exposed crater rim, 0°12’20”S, 90°47’3”W, 840 m, humid zone, on rock, 23 Mar 2006, Aptroot, A. 65699 ( CDS 32291) , along trail to summit above Santiago Bay lava flow, 0°12’35”S, 90°47’5”W, 895 m, humid zone, on rock, 30 Apr 1971, Pike, L.H. 2722 ( OSC 54939) .

Figures

FIGURE 5. a the predominantly sorediate podetia of Cladonia macilenta (Bungartz 7758, scale 3 mm); b highly dissected, minute squamules with very short podetia, characteristic of Cladonia nana (Aptroot 64501, scale 5 mm); c–d Cladonia polyscypha. c general growth aspect (Bungartz 3970, scale 5 mm); d close-up with podetia terminating in narrow scyphi (Aptroot 64514, scale 5 mm); e podetia of Cladonia pulverulenta (Aptroot 64518, scale 5 mm); f broad, trumpet-shaped podetia with coarse corticate granules