NEW ZEALAND: South Island, Prov. Westland, Ahaura, Kopara, Nelson Creek, Bridge across Haupiri River, 11 II 1968, Horak 68-76 (ZT); Prov. Nelson, Murchison, Buller Gorge Bridge, 11 II 1969, Horak 69-59 (SFSU, ZT); Prov. Nelson, Murchison, Buller Bush, 14 V 1948, Stevenson in Horak 70-269 (ZT).- INDONESIA: Java, Bogor, Tjibodas, on rotting leaves of Freycinetia banksii (Pandanaceae) and Castanopsis sp. (Fagaceae), 1850 m, 15 III 1977, Horak 77-191 (SFSU, ZT).

Pi1eus 2-6 mm diam, hemispherical to convex when young, expanding with age to plano-convex; disc with or without an inconspicuous obtuse papilla; margin subplicate; surface dull, dry, glabrous to minutely innately fibrillose; disc brown, pale reddish brown elsewhere. Texture membranaceous, tough; context thin.- Lamellae subfree to adnexed, subdistant (11-13) with 1-2 series of lamellulae, narrow, white to cream with pale reddish tones; edges even, concolorous.- Stipe 15-30 x 0.3-0.5 mm, central, cylindrical, equal, glabrous, tough, insititious; orangish yellow overall, base developing pale reddish orange tones in age; with scattered yellow, wiry rhizomorphs.- Odor and taste not distinctive.
Basidiospores (5.5-)6.0-7.5 x (2.5-)3.0-3.5 µm, narrowly ellipsoid, smooth, thin-walled, hyaline, inamyloid-. Basidia 20-26 x 4-6 µm, cylindrical to subclavate, 4-spored, clamped.- Cheilocystidia common, (15)20-40 x 8-15(-25) µm, clavate, broadly clavate or sphaeropedunculate with numerous diverticula over the upper half, hyaline, thin-walled or apically thick-walled; diverticula 2-6 x 1-2 µm, cylindrical or irregular in outline, rarely forked, hyaline.- Pleurocystidia absent.- Pileipellis a subhymeniform layer of clavate to irregular, sometimes lobed cells 15-25 x 6-20 µm, densely diverticulate, yellowish brown, thin-walled; diverticula 2-7 x 1-21 µm, cylindrical or irregular in outline, rarely forked, pale yellowish brown.Pi1ea1 trama weakly dextrinoid; lamellar trama inamyloid.- Stipe tissue monomitic; cortical hyphae smooth, golden, strongly dextrinoid; medullary hyphae hyaline, dextrinoid.- Cau1ocystidia absent.- Clamp connections present.

Habit, habitat and distribution.- Solitary in groups, on rotting leaves of Nothofagus fusca (Fagaceae; holotype), Aristotelia serrata (Elaeocarpaceae), or Laurelia novaezelandiae (Lauraceae). Java, New Zealand.

Pileus 2-6 mm, convexus dein planoconvexus, rariter papilla obtusa instructus, subplicatus, glaber vel minute fibrillosus, brunneus ad discum sursum pallide castaneus. Lamellae adnexae vel subliberae, subdistantes, albae vel cremeae. Stipes 15-30 x 0.3-0.5 mm, centralis, cylindricus, glaber, insititius, pallide aurantioluteus, rhizomorphis luteis strigosis ad basim instructus. Odor saporque nulli. Basidiosporae 6.0-7.5 x 3.0-3.5 µm, anguste ellipsoideae, leves, hyalinae, inamyloideae. Basidia 20-26 x 4-6 µm, 4-spora. Cheilocystidia 20-40 x 8-15 µm, ex clavatis sphaeropedunculata, diverticulis cylindrcus vel irregularibus, 2-6 x 1-2 µm, instructa. Pleurocystidia nulla. Pileipellis subhymeniformis, ex cellulis clavatis, 1525 x 6-20 µm, valde diverticulatis, 2-7 x 1-2 µm, membrana tenuitunicata et pallide luteobrunnea instructa. Trama pilei subdextrinoideum. Hyphae stipitis corticales glabrae, aurantiacae, valde dextrinoideae. Caulocystidia nulla. Fibulae praesentes. Solitarius, ad folia putrida Nothofagi fuscae (holotypus), Aristoteliae serratae vel Laureliae novaezelandiae. Nova Zelandia. Horak 68-33 (Holotypus, PDD).

Marasmius aurantiobasalis is characterized by a reddish brown pileus, subdistant, non-marginate lamellae, a glabrous, orangish yellow stipe associated with yellow wiry rhizomorphs, relatively narrow basidiospores, broadly clavate and densely diverticulate cheilocystidia, a subhymeniform pileipellis of diverticulate_, terminal cells, no caulocystidia, and growth on leaves of dicotyledonous trees. The orangish yellow stipe contrasting with a reddish brown pileus is reminiscent of M. acicularis Berk. and M. straminipes Peck. Marasmius acicularis, described from the Bonin Islands, differs in forming a pileipellis composed of a hymeniform layer of Siccus-type cells and consequently belongs in sect. Sicci (Isotype, FH!). Marasmius straminipes from eastern North America differs in forming a paler pileus (often cream to pale greyish brown), slightly longer and broader basidiospores (6.5-10 x 3.2-4.5 µm), and more irregularly shaped and narrower cheilocystidia (Holotype, NYS!; see Desjardin & Petersen 1989b). A variety from New Caledonia with hispidulous stipe and numerous caulocystidia is described as M. aurantiobasalis var. hispidipes in Part I of this series on South Pacific marasmioid fungi.

NEW ZEALAND: South Island, Prov. Westland, Ahaura, Kopara, Nelson Creek, 17 I 1968, Horak 68-33 (Holotype, PDD; Isotype, SFSU, ZT)

Pileus 2-6 mm latus, hemisphaericus vel convexus, papilla obtusa vel nulla instructus, subplicatus, minute fibrillosus, pallide rubrobrunneus, ad discum obscurior. Lamellae subliberae vel adnexae, subdistantes, albae dein cremeae pallide roseae tinctae. Stipes 15-30 x 0.3-0.5 mm, aequalis, cylindricus, glaber, cartilagineus, insiticius, ochraceoaurantius, rhizomorphis luteis nonnullisque instructus. Basidiosporae (5.5-)6.0-7.5 x (2.5-)3.0-3.5 µm, anguste ellipsoideae, leves, hyalinae, inamyloideae. Basidia 20-26 x 4-6 µm, 4-spora. Cheilocystidia (15)20-40 x 8-10(-25) µm, clavata, hyalinia, diverticulis 2-6 x 1-2 µm longis, cylindraceis irregularibusque et membrana ad apicem subincrassata instructa. Pleurocystidia nulla. Pileipellis subhymeniformis ex cellulis clavatis vel irregulariter lobatis, 15-25 x 6-20 µm, membrana luteobrunnea et tenuitunicata instructa, diverticulis numerosis, 2-7 x 2 µm longis, cylindraceis vel irregularibus instructus. Trama pilei subdextrinoidea. Fibulae praesentes. Solitarius ad foliis putridis Nothofagi fuscae. Nova Zelandia. Holotypus: Horak 68-33 (PDD).

Marasmius aurantiobasalis var. aurantiobasalis is currently known only from New Zealand. A further accounting of the variety is presented in Part 2 of this series on South Pacific marasmioid fungi. As with the type variety (known only from New Zealand), var. hispidipes is easily recognized by the reddish brown pileus contrasting with a yellowish orange stipe, relatively narrow basidiospores, and growth on leaves of broad-leaved trees. Marasmius aurantiobasalis var. hispidipes differs from var. aurantiobasalis only in forming a hispidulous stipe covered with lanceolate, acute caulocystidia. The species is most closely allied with M. straminipes var. fibulatus Desjardin & Petersen, described from material collected on oak leaves in southeastern United States. The latter species differs from M. aurantiobasalis in forming a cream-colored to greyish brown pileus, slightly longer (6.5-10 µm) and broader (3.2-4.5 µm) basidiospores, and more irregularly shaped and narrower cheilocystidia (compare with #28 below; Desjardin & Petersen, 1989).