Tulostoma giganteum J.E.Wright nov. sp. (Fig. 68; Pl. XXXI: 5)
Etym.: the name refers to the large size of the spore-sac and of the plant as a whole.
Latin diagnosis:
Plantae e stipite peridioque compositae; peridium pengrande, usque 32 mm diam, depresso-globosum usque fere hemisphericum; exoperidium subgranulosum, hyphale vel submembranaceum, ad basim in forma calyicis glandis persistente; endoperidium non glabrum, sordide album; stipes pallidus, fibroso-lignosus, 6 mm diam, ad basim subattenuatus, squamulis fragilibus inaequalibus praeditus; os indefinitum, laceratum; collare valde umbilicatum, perconspicuum sine membrana distincta, usque 15 x 7 mm; gleba obscure ferruginea; sporae obscure brunneae, globosae, 5.4-6.6 µm diam magnopere verrucoso-tuberculatae, tuberculis nonnihil sparsis ver interdum anastomosantibus, episporio crasso; sub microscopio electronico verrucis pyramidalibus rotundatis exornatae, columniformibus, verrucis minutis anastomosantibus intermixtae; endoperidium hyphis abrupte septatis compositum, septis numerosis coloratisque, disjunctis, muris hyphalibus inaequaliter crassis, lumine evidenti, irregulari, 3.6-7.8 µm diam.
Hab. in solo arenoso humifero in silva intermixta.
Holotypus: America boreali, California, San Francisco, Golden Gate Park, leg. E. Whited, 6.XI.1934 in Herb. UC n° 628.866, sub T, campestre Morgan conservatus est.
Spore-sac very large, up to 32 x 20 mm, globose-flattened. Endoperidium formed by a very thin hyphal layer mixed with sand and soil particles, appearing in some instances submembranaceous. Endoperidium whitish, finally smooth. Mouth indefinite, appearing as a plane aperture hardly insinuated in the endoperidium. Socket very deep, up to 10 x 8 mm, with an entire membrane. Gleba dark ferrugineous brown. Stem woody, cream-coloured, up to 80 x 8 mm, with a bulbose base and pl: Wii-ded with a volviform basal structure, fragile.
Spores distinctly echinulate, dark brown, appearing with smaller verrucae among langer and more acute ones when observed under L.M., episporium thick, 5.9-7.8 µm diam. Under SEM the ornamentation appears formed by pyramidal, blunt verrucae composed of indistinct columns intermixed with smaller, anastomosed verrucae, those near the apiculus being smaller and more globose. Capillitium subhyaline, branched and sparsely septate, hardly swollen at the uncoloured, disjointable septa; 3.4-10.2 µm diam.
Habitat: In very humiferous sandy soil in mixed woods.
Distribution: North America: United States: it appears so far restricted to the San Francisco area, but no doubt further search will reveal a wider range of distribution.