Hygrocybe lamalama Desjardin et Hemmes, sp. nov.

Pileus (5-)10-20(-40) mm latus, semiglobatus vel convexus, dein late convexus, saepe disco depressus, haud striatus, glaber, subhygrophanus, siccus, cadmio-aurantiacus ad margine croceus, dein croceus vel pallide croceus. Lamellae late adnatae, sinuatae vel emarginatae, subdistantes, latae, pallide luteae vel luteae, dein croceae vel aurantioluteae. Stipes (10-)15-45 X 1.5-3.0(-5.0) mm, aequalis, solidus vel fistulosus, glaber, siccus, cadmioaurantiacus, croceus vel aurantioluteus. Odor et sapor nulli. Sporae 6.5-9.0(-9.5) X (4.5-)5-6.5 µm, ellipsoideae vel obpyriformes, constrictae. Basidia 31-45 X (6.5-)7.0-9.0 µm, tetrasporigera, pro parte bisporigera. Cheilocystidia et pleurocystidia nulla, lamellarum acies fertilis. Pileipellis cutiformis, ex hyphis (4-)5-16 µm latis, cylindraceis, haud gelatinosis, cellulae terminales repentes, cylindraceae vel clavatae, (24-)32-80 X 7-18 µm. Lamellarum trama subregularis, cellulis brevibus, inflatis vel cylindraceis, 58-120 X 3-14 µm. Stipitepellis cutiformis. Caulocystidia nulla. Fibulae praesentes. Holotypus: Hawai`i, Saddle Rd. at 21 mi kipuka, 13 Jan 1992, D. E. Desjardin 5505 (SFSU; Isotypus: BISH).

Pileus (Fig. 49) (5-)10-20(-40) mm diam, hemispheric to convex when young, expanding at maturity to broadly convex, often with a shallow central depression; margin incurved when young, becoming decurved, even or sometimes wavy in age, non-striate or only weakly pellucid striatulate when moist; surface dry or moist to lubricous (not viscid), subhygrophanous, dull, glabrous, sometimes in age with scattered pruinae (not scurfy, squamulose nor fibrillose); when young disc deep orange (5A6-8; cadmium orange) and margin deep yellow (4A6-8; cadmium yellow) to yellow (3A4-6), or deep yellow overall, in age often losing the orange tones and becoming deep yellow, yellow or pale yellow (3-4A2-3) overall, seldom with a hint of orange remaining on the disc, lacking red tones throughout development. Context up to 2.5 mm thick, watery-concolorous with pileus surface. Lamellae broadly adnate, sinuate or emarginate, ascending to horizontal, subdistant with 2-3 series of lamellulae, broad (2-4 mm), convex, relatively thick; when young pale yellow (3A2-3) to yellow (3A4-5), becoming deep yellow (4A5 7) to orange (5A4-6) in age, lacking red tones. Stipe (10-)15-45 X 1.5-3.0(-5.0) mm, central, terete, equal or with a flared apex, straight or curved, solid becoming fistulose at maturity, dull, dry, shiny, glabrous except at the base which is covered with white to pale yellow (3-4A2-3) tomentum; surface concolorous with the pileus, deep orange to deep yellow or orangish yellow overall. Odor not distinctive; taste not distinctive or mildly astringent.
Basidiospores (Fig. 50) 6.5-9.0(-9.5) X (4.5-)5-6.5 µm [range of means = 7.6-8.2 X 5.2-5.3 µm, mean of means = 8.0 ± 0.3 X 5.3 ± 0.05 µm, Q = 1.3-1.7, range of Q means = 1.46-1.58, mean of Q means = 1.51 ± 0.05, n = 25-30 spores per 7 specimens], ellipsoid to inequilateral in profile, obpyriform in frontal view, 50-70% constricted, smooth, hyaline, inamyloid, thin-walled; white in deposit. Basidia (Fig. 51) 31-45 X (6.5-)7.0-9.0 µm, 4-spored, rarely 2-spored, clavate, clamped. Hymenial cystidia absent. Pileipellis (Fig. 52) a cutis over disc and margin (never a trichodermium); hyphae (4-)5-16 µm diam, cylindrical or slightly inflated, somewhat interwoven, repent with repent to suberect or rarely erect terminal cells (pileocystidia), nongelatinous, nonincrusted, hyaline, inamyloid; pileocystidia scattered, (24-)32-80 X 7-18 µm, cylindrical to clavate, broadly obtuse, hyaline, thin-walled. Pileus trama of interwoven hyphae nearly indistinguishable from the pileipellis, cells inflated to fusoid, 40-100 X 12-18 µm, with long-cylindrical cells 3-8 µm diam interspersed, nongelatinous. Hymenophoral trama subregular; hyphae 58-120 X 3-14 µm, cylindrical or slightly inflated, nongelatinous. Stipe tissue monomitic; hyphae 3-14 µm diam, cylindrical, nongelatinous, hyaline, inamyloid. Stipitipellis a cutis; hyphae 3-8 mm diam, slightly interwoven, terminal cells repent to erect; caulocystidia not differentiated. Stipititrama hyphae 68-120(-160) X 5.5-13.5 µm. Clamp connections present in all tissues.B>Habit, habitat and distribution. Solitary to scattered, seldom gregarious, in soil or among mosses (mainly Rhizogonium sp.) in Montane Mesic Forest (Ohi`a Forest) and Montane Wet Forest (Ohi`a Forest), or seldom in Montane Mesic Forest dominated by koa (Acacia koa A. Gray); one population (on Moloka`i) growing at the interface between Montane Wet Forest and alien conifer forest dominated by loblolly pine (Pinus taeda) and Monterey Cypress (Cupressus macrocarpa). December to January. Hawai`i, Kaua`i, Maui, Moloka`i.
Specimens Examined. U.S.A. HAWAII: Hawai`i, Saddle Rd. at 21 mi kipuka, 13 Jan 1992, DED 5505 (Holotype); same location, 2 Dec 1990, DEH 12.2.90.1; same location, 6 Dec. 1994, DEH 654; same location, 20 Dec. 1994, DEH 673; Hawai`i, Saddle Rd. at 19 mi kipuka, N 19°40.550', W 155°20.180', 14 Nov. 1995, DEH 918; Hawai`i, Saddle Rd. at 18.5 mi kipuka, N 19°40.691', W 155°19.425', 13 Jan 1992, DED 5512; same location, 6 Dec. 1994, DEH 655; Hawai`i, Natural Area Reserve System, Pu`u Maka`ala, N 19°29.072', W 155°16.140', 21 Aug. 1996, DED 6549. Kaua`i, Koke`e State Park, Kahuamaa Flat near Kalalau Lookout, 5 Jan 1994, DED 5981; Kaua`i, Koke`e State Park, Kaluhapuhi Trail, ca N 22°08.530', W 159°38.750', 9 Jan. 1996, DED 6380; Kaua`i, Koke`e State Park, Pu`u Ka Ohelo Berry Flat Trail, between N 22°07.158', W 159°38.725' and N 22°08.158', W 159°38.585', 7 Jan. 1995, DED 6196; Kaua`i, Milolii Ridge Trail off Makaha Ridge Trail, N 22°07.160', W 159°40.166', 9 Jan. 1996, DEH 963. Maui, West Maui Mts., Pu`u Kukui, 17 Jan. 1994, DEH 404. Moloka`i, Kamakou Forest Preserve (The Nature Conservancy Hawai`i), Kamoku Flats, N 21°07.101', W 156°55.122', 11 Jan. 1994, DED 6034; same location, 11 Jan 1994, DEH 380; same location, 9 Jan. 1995, DED 6219; Moloka`i, Kamakou Forest Preserve, Hanalilolilo Trail, N 21°07.554', W 156°54.882', 12 Jan. 1996, DED 6397; same location, 9 Jan. 1995, DEH 715.
Etymology. "lamalama" - Hawaiian for "to glow as if touched by the sun."
Commentary. Hygrocybe lamalama is characterized by the following features: convex, glabrous, dry, deep orangish yellow pileus; adnate to emarginate yellow lamellae; dry, orangish yellow stipe; constricted basidiospores with range of w = 5.2-5.3 µm (mean of Q means = 1.5); subregular hymenophoral trama; pileipellis a cutis composed of hyphae 5-16 µm diam with clavate terminal cells 7-18 µm diam; and habit in tropical montane wet forests dominated by Metrosideros (Myrtaceae) and Cibotium (Dicksoniaceae). In combination, these features suggest placement in subgen. Pseudohygrocybe M. Bon, sect. Coccineae Fay., subsect. Coccineae (Bataille) Singer where it is phenetically similar to a number of taxa with constricted spores, including H. obrussea (Fr.: Fr.) Wünsche from Europe [= H. quieta (Kühner) Singer sensu Boertmann], H. constrictospora Arnolds from Europe and Hawai`i, H. venusta Hongo from Japan, and Hygrophorus parvulus Pk. from North America. All of the latter four species differ significantly from H. lamalama in forming narrower basidiospores (3.5-5 µm wide; range of w = 3.7-4.7 µm; range of Q means = 1.7 2.0) and much narrower pileipellis hyphae (1.5-7 µm diam). In addition, H. obrussea differs in forming typically more robust basidiomata often with red tones in pileus and stipe and deeper orange lamellae, a strong sweet odor like Lactarius quietus Fr., and habit usually in grasslands (fide Arnolds, 1990). Hygrocybe constrictospora, which occurs in the same native forests on Hawai`i, differs in forming a deep red pileus, orange lamellae, and a reddish orange stipe. Hygrocybe venusta differs in forming pale yellow adnato-subdecurrent lamellae and habit in pine forests (fide Hongo, 1984). Hygrophorus parvulus differs in forming pale yellow decurrent lamellae, stipe tinged pinkish red, and a subgelatinous pileipellis (fide Hesler and Smith, 1963). DD>The absence of reddish tones in basidiomes, the development of broad basidiospores and especially the broad pileipellis hyphae of H. lamalama are more reminiscent of several species in subsect. Squamulosae (Bataille) Singer, viz., H. cerinolutea Horak from New Zealand, and H. miniata var. mollis (Berk. & Br.) Arnolds from Europe and North America. Because of these micromorphological congruences, H. lamalama may be better placed in subsect. Squamulosae, albeit with a pileus lacking squamules. Both H. cerinolutea and H. miniata var. mollis differ significantly from H. lamalama in having scurfy to squamulose pilei with trichodermial pileipelles (at least over the disc). In addition, H. cerinolutea differs in forming larger, non-constricted or few slightly constricted basidiospores (mean = 12.5 X 7.8 µm) and much longer basidia (50-84 µm) (Holotype ZT!), while H. miniata var. mollis forms more distinctly striate pilei and consistently narrower basidiospores (range of w = 4.0-5.0 µm) (fide Arnolds, 1974, 1986a, 1995; Largent, 1985; specimens at SFSU). It is interesting that H. cerinolutea is also associated with Metrosideros. Hygrocybe substrangulata (P. D. Orton) P. D. Orton & Watling is also superficially similar, but differs in forming deep orange to orangish red basidiomes with squamulose pilei, and much larger basidiospores (9-15 X 5-6.5 µm; fide Boertmann, 1995; Borgen and Senn-Irlet, 1995). Although H. lamalama is phenetically similar to the three aforementioned species, its pileipellis anatomy and habit in tropical insular montane wet forests is sufficiently distinctive to warrant recognition as an autonomous species.
Hygrocybe lamalama has been collected on Kaua`i, Maui, Moloka`i and Hawai`i, only in native montane forests dominated by ohi`a and hapu`u. Because of its restricted occurrence in these endemic forests, we consider H. lamalama to represent a native, possibly endemic species.

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