Typification: OAHU, HAWAII, USA: Mokuleia Forest Reserve, 318 m, 18 April 2015, J. Hayward S13O (holotype HAW-F-00087).
Etymology: The specific epithet “uliuli” is a Hawaiian word indicating the color green as in vegetation, for the color of the mature gleba.
Basidiomata erumpent or more usually epigeous, solitary or more rarely gregarious, up to 2.8 cm in diameter × 1.9 cm in height, subglobose, sessile, with abundant white to pale yellow rhizomorphs and unaggregated basal mycelium emerging from a single point of attachment, odor not distinct. Surface with yellow-brown (5 YR 5/10 to 7.5YR 7/12) irregularly polygonal scales with 3-8 angles, at maturity 360-880 μm across the widest dimension, less than 250 μm in height, separated by veins of off-white (7.5YR 9/8) context 120-200 μm in width. Rupturing irregularly at apex at maturity with progressive loss of peridium; specimens in age frequently without peridial remnants in the upper hemisphere. Gleba white in immaturity, then briefly yellow, later gray (10YR 9/2, then 10YR 9/8, finally N1) with lighter gray veins (N7), and finally green (10GY 3/4 to 10GY to 10GY 3/6), with yellow (5Y 8/8) hyphal threads; composed in immaturity of irregular chambers 30-890 μm in diameter supported on meandering white tramal veins 8-102 μm in width, at maturity tramal veins becoming indistinct and finally absent; glebal contents in immaturity hard and waxy, at maturity dry and powdery.
Spores (9.0) 10.09-10.48-10.87 (12.51) μm in diameter including ornamentation, (6.4) 7.12-7.60-7.95-(8.9) μm excluding ornamentation, greenish (2.5G 2/2) globose; ornamentation consisting of spines 1.30-1.63 μm in length, at base 0.85-1.83 μm in diameter, separated by bare patches 0-0.54 μm in width. Glebalhyphaepale yellow,thick-walled, minutely incrusted, 2.4-5.6 μm in diameter.Basidianot evident at maturity, in immature basidiomata pyriform or with a distinct apical inflated region and a basal constricted region, the inflated region 7.0-8.5 μm in diameter, at base 2.8-4.2 μm in diameter, overall 11.7-24.5 μm in length, arising in clusters of 2-5 basidia from elongate elements, with 4 or rarely 5 cylindrical sterigmata 2.5-2.8 μm in length and 1.4-1.6 μm in diameter.
Peridium 600-880 μm thick, distinctly two-layered; the outer layer yellow (5Y 8/10), the inner layer white. Endoperidium 400-675 μm in depth, a loose trichodermium of thick-walled hyphae 2.8-3.4 μm in diameter, with occasional yellow oleiferous hyphae of similar diameter. Exoperidium 240-290in depth,pseudoparenchymatic, consisting of thick-walled pigmented cells inflated 6.0-17.9 μm, with rare uninflated elements 3.0-4.7 μm.
Rhizomorphs well-differentiated, consisting of a superficial cutis of interwoven and branching thick-walled 3.5-5.3 hyphae μm in diameter, with occasional clavate to sphaeropedunculate cystidiod terminal elements, 5.2-8.4 μm in diameter, overlaying dense bundles of parallel hyphae 3.3-4.1 μm in diameter, with occasional large inflated elements up to 12.6 μm in diameter.
Comments: This species is intermediate in commonness between Clavulina aulu and Russula kualapa. It can be found even during the dryer summer months on Oahu. The nonreticulate, aculeate ornamentation places this species in section the section Aculeatispora of Guzman (1970). Guzman (1970) placed S. cepa, S. areolatum, S. albidum, and S. laeve in section Aculeatispora; so far as we are aware, the only species described since 1970 potentially referable to this section on the basis of its morphology is S. yunnanense Y. Wang, which unlike our species possesses clamp connections, and which is not closely related to other members of the section (Zhang et al. 2013). This species is distinct from all of those species through the combination of its sessile habit, thin peridium, green (rather than yellow, umber, ochre, etc.) spores, and green gleba at maturity.
Specimens examined: OAHU, HAWAII, USA: Mokuleia Forest Reserve, 410 m, 18 April 2015 Hayward S14O; OAHU, HAWAII, USA: Mokuleia Forest Reserve, 367 m, 1 March 2015: Hayward S12O; HAWAII ISLAND, HAWAII, USA: South Kona forest Reserve, 575 m, 21 May 2014: Hayward S1H; HAWAII ISLAND, HAWAII, USA: South Kona forest Reserve, 580 m, 21 May 2014: Hayward S2H; OAHU, HAWAII, USA: Manuwai Gulch, 480 m, 6 February 2015: Hayward S14O.