Humidicutis peleae Desjardin et Hemmes, sp. nov.

Pileus 8-25(-35) mm latus, conicus vel campanulatus, dein late campanulatus vel planoumbonatus, striatulus, glaber, siccus, aurantiacus, dein pallide aurantiacus. Lamellae adnatae, subdistantes vel distantes, latae, intervenosae, profunde aurantiaceae. Stipes 15-45 X 1.5-3 mm, aequalis, glaber, siccus, apicaliter aurantiacus vel luteoaurantiacus, deorsum alboaurantiacus vel albus. Odor et sapor nulli. Sporae (5.8-)6.4-8.0(-8.5) X (4.2-)4.5-5.0(-5.4) µm, ellipsoideae, haud constrictae. Basidia (28-)33-43 X (6.5-)7.0-8.5(-9.5) µm, tetrasporigera, pro parte 1-, 2-, vel 3-sporigera. Cheilocystidia et pleurocystidia nulla, lamellarum acies fertilis. Pileipellis cutiformis, ex hyphis 3.2-9.5 µm latis, cylandraceis, haud gelatinosis. Lamellarum trama subregularis, ex cellulis brevibus, inflatis vel cylindraceis, 24-60 X 8-24 µm. Stipitepellis cutiformis. Fibulae typi medallionei ad basidia praesentes, ceterum desunt. Holotypus: Hawai`i, Wailuku Bog off Saddle Rd. at 14 mi marker, 7 Jul. 1994, D. E. Hemmes 492 (SFSU; Isotypus: BISH).

Pileus (Fig. 31) 8-25(-35) mm diam, conic or obtusely conic to campanulate with incurved margin when young, expanding with maturation to broadly campanulate, plano-umbonate or depressed with prominent umbo and uplifted margin; surface moist to dry (not viscid), hygrophanous, glabrous, margin striatulate in age; deep orange (6-7A7-8) overall when young, fading overall in age and with moisture loss through orange (5A7-8 to 6A4-6) to light orange (5A3-4; 6A3), seldom orange white at maturity; lacking red, reddish brown, olive, or yellow tones. Context thin (0.5-1.5 mm), watery, white or pale orange white. Lamellae ascending to horizontal, adnate or adnate with a decurrent tooth, subdistant to distant with 1-3 series of lamellulae, broad (2-4 mm), thick, sometimes transvenose to intervenose in age; deep orange overall (6A6-8) and remaining so in age. Stipe 15-45 X 1.5-3 mm, central, terete, equal or seldom slightly enlarged near the base, straight to curved, dull, moist to dry (not viscid), glabrous above, base glabrous or minutely pruinose, fragile, hollow; when young apex orange (6A5-6) to yellowish orange (5A4-6), base orange white (5A2), at maturity apex light orange (5A3-4) or pale orange white (5A2), base pale orange white, pale yellowish white (4A2) or buff, sometimes stipe buff to nearly white overall in age. Odor not distinctive; taste not distinctive or faintly sweet.
Basidiospores (Fig. 32) (5.8-)6.4-8.0(-8.5) X (4.2-)4.5-5.0(-5.4) µm [range of means = 6.6-7.4 X 4.6-4.8 µm, mean of means = 7.1 ± 0.3 X 4.7 ± 0.1 µm, Q = 1.3-1.7, range of Q means = 1.45-1.54, mean of Q means = 1.49 ± 0.04, n = 20-25 spores per 8 specimens], rarely 10.0-11.5 X 6.0-7.5 µm from 1- or 2-spored basidia, ellipsoid, inequilateral in profile, with a prominent broad hilar appendix, hyaline, smooth, inamyloid, white in deposit. Basidia (Fig. 33) (28-)33-43 X (6.5-)7.0-8.5(-9.5) µm, predominantly 4-spored, seldom 1-, 2- or 3-spored (one specimen with numerous 1-spored basidia), clavate, hyaline, with large medallion clamp at the base. Hymenial cystidia absent. Pileipellis a cutis; hyphae 3.2-9.5 µm diam, subparallel to slightly interwoven, radially arranged, cylindrical, nongelatinous, nonincrusted, hyaline, inamyloid, thin-walled. Pileus trama of interwoven hyphae 3-16 µm diam, inflated to fusoid, otherwise like pileipellis hyphae. Hymenophoral trama subregular, many hyphae cylindrical, 2.5-6.5 µm diam, many fusoid to nearly ovoid, 24-60 X 8-24 µm, hyaline, nongelatinous; with a few oleiferous hyphae interspersed; subhymenium nongelatinous. Stipe tissue monomitic; stipitipellis a cutis; cortical and medullary hyphae undifferentiated; hyphae 2.5-10(-12) µm diam, parallel, otherwise like pileipellis hyphae. Caulocystidia absent. Clamp connections present at base of basidia, absent elsewhere.
Habit, habitat and distribution. Solitary to scattered, on bryophyte-covered soil or among bryophytes on rotten logs of ohi`a (Metrosideros polymorpha) or stems of hapu`u (Cibotium spp.) in Montane Wet Forest (Ohi`a/Hapu`u Forest) or Montane Mesic Forest (Ohi`a Forest), rarely in duff under Monterey Cypress (Cupressus macrocarpa) adjacent to Montane Wet Forest. All months. Hawai`i, Kaua`i, Maui, Moloka`i.
Specimens Examined. U.S.A. HAWAII: Hawai`i, Wailuku Bog off Saddle Rd. at 14 mi marker, 7 Jul. 1994, DEH 492 (Holotype); Hawai`i, Saddle Rd. at 18.5 mi kipuka, N 19°40.691', W 155°19.425', 26 May 1993, DED 5716; same location, 6 Jun. 1994, DEH 456; Hawai`i, Saddle Rd. at 18.5 mi kipuka, 1000 steps site, N 19°40.710', W 155°19.778', 20 Aug. 1996, DED 6526; Hawai`i, Saddle Rd. at 19 mi kipuka, N 19°40.550', W 155°20.180', 28 Nov. 1995, DEH 932; Hawai`i, Saddle Rd. at 21 mi kipuka, 13 Jan. 1992, DED 5506; same location, 2 Dec. 1990, DEH 12.2.90.1; Hawai`i, Natural Area Reserve System, Pu`u Maka`ala, N 19°29.072', W 155°16.140', 4 Aug. 1993, DED 5877; same location, 26 Sept. 1994, DEH 584; same location, 21 Aug. 1996, DED 6550. Kaua`i, Koke`e, Na Pali-Kona Forest Reserve, Pihea Trail, 4 Oct. 1994, DEH 612 & DEH 614. Maui, West Maui Mts., Pu`u Kukui, 17 Jan. 1994, DEH 407. Moloka`i, Kamakou Forest Preserve, Kamoku Flats, N 21°07.101', W 156°55.122', 11 Jan. 1994, DEH 376; same location , 9 Jan. 1995, DED 6221; Moloka`i, Kamakou Forest Preserve, Hanalilolilo Trail, N 21°07.554', W 156°54.882', 9 Jan. 1995, DED 6208; same location, 12 Jan. 1996, DED 6398.
Etymology. "peleae" - named in honor of Pele, the Hawaiian volcano goddess.
Commentary. The genus Humidicutis is distinguished from Hygrocybe by the absence of clamp connections in all tissues (except at the base of basidia where large medallion clamps occur from which other basidia may proliferate), and by the type of pigments (absence of muscaflavin; Singer, 1986; see also Singer, 1958). Humidicutis peleae is distinguished by its small delicate basidiomes with deep orange, non-viscid, hygrophanous pileus, deep orange lamellae, and pallid narrow stipe. It is closely allied with Humidicutis marginata (Pk.) Sing. from North America and H. conspicua (Horak) Horak from New Zealand. Humidicutis marginata is a more robust species with pilei averaging 20-40 mm diam and stipes 40-100 X 3-8 mm, forms larger basidiospores (range of means = 7.5-8.2 X 5.1-5.6 µm, mean of means = 7.9 ± 0.3 X 5.4 ± 0.2 µm), and has consistently narrower hymenophoral tramal hyphae (reaching only 15 µm diam). Humidicutis conspicua is also a more robust species (pilei up to 35 mm diam, stipes 15-75 X 3-15 mm) with reddish brown pileus disc, an unpleasant odor and taste (like rotten meat), and slightly smaller basidiospores measuring 6.0 7.7 X 4.0-4.5 µm (mean = 7.0 ± 0.4 X 4.3 ± 0.2 µm; Holotype ZT!).
Like most Hawaiian Hygrocybe species, Humidicutis peleae is restricted to high elevation native forests and is considered by us to represent a native Hawaiian species, possibly endemic. This species was reported by Doyle (1985, unpublished) as Hygrocybe sp.

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