Agaricales of the Hawaiian Islands

Key to Hawaiian Hygrophoraceae

The following artificial dichotomous key is designed to aid in the identification of hygrophoroid species occurring in the Hawaiian Islands. Data presented in the key pertain strictly to Hawaiian populations.

1. Hymenophoral trama divergent.......... Hygrophorus (no species in the Hawaiian Islands)
1. Hymenophoral trama regular to subregular.......... 2

2. Pileipellis hymeniform, composed of broadly clavate to sphaeropedunculate cells.......... Camarophyllopsis hymenocephala
2. Pileipellis not hymeniform, composed of a cutis, an ixocutis, a trichodermium or an ixotrichodermium.......... 3

4. (3) Pileus < 10 mm diam, convex to plano-convex or plano-umbilicate, deep red, not blackening in age or where bruised; lamellae broadly adnate; stipe 4-10 X 0.5-1 mm, deep red.......... Hygrocybe mexicana f. defibulata
4. Pileus > 10 mm diam, conic, expanding to conico-campanulate, red when young but soon developing orange and yellow tones, blackening in age or where bruised........... 5

5. Basidiospores cylindrical to phaseoliform-oblong, mean = 11.6 X 4.9 µm, Q = 2.0-2.6; lamellae salmon-orange when dried.......... Hygrocybe conicoides
5. Basidiospores variable but typically ellipsoid to ovoid, mean = 9.9 X 7.1 µm, Q = 1.2-1.7; lamellae black when dried.......... Hygrocybe conica

6. (3) Pileus and stipe viscid to glutinous.......... 7
6. Pileus and stipe dry to lubricous or greasy.......... 11

7. Pileus pink to pale greyish red, lacking deep red, orange, yellow, or olive tones; cheilocystidia abundant, filamentous.......... 8
7. Pileus deep red, orange, yellow or with olive tones; cheilocystidia absent............. 9

8. Clamp connections present; cheilocystidia 16-45 (-55) µm long.......... Hygrocybe noelokelani var. noelokelani
8. Clamp connections absent; cheilocystidia 38-80(-100) µm long.......... Hygrocybe noelokelani var.defibulata

9. (7) Pileus and stipe deep red to reddish orange; hymenophoral trama composed of hyphae 100-300 µm long.......... Hygrocybe aff. minutula
9. Pileus and stipe orange, yellow or with olive tones, lacking red tones; hymenophoral trama composed of hyphae 28-160 µm long.......... 10

10. Pileus and stipe glutinous when young, viscid at maturity; stipe 2-3 mm thick; pileus deep orange, often with olive tones; basidiospores with mean range = 8.4-9.0 X 5.0-5.4 µm ; pileipellis and stipitipellis an ixotrichodermium.......... Hygrocybe pakelo
10. Pileus and stipe viscid when young, merely subviscid at maturity; stipe < 1 mm thick; pileus orange to pale orange, lacking olive tones; basidiospores with mean range = 6.2-7.5 X 3.9-4.7 µm; pileipellis and stipitipellis an ixocutis.......... Hygrocybe hapuuae

11. (6) Clamp connections absent in most tissues, present only at base of basidia, large and medallion-like, basidia often proliferating from clamps; pileus obtusely conical to campanulate, becoming broadly campanulate to plano-umbonate..........Humidicutis spp. ............ 12
11. Clamp connections present in all tissues, not medallion-like; pileus convex to plano-convex, often depressed to umbilicate.......... 13

12. Pileus deep orange to orange, becoming pale orange in age; lamellae bright orange; basidiospores with mean range = 6.6-7.4 X 4.6-4.8 µm.......... Humidicutis peleae
12. Pileus deep yellow, becoming yellow in age; lamellae light yellow; basidiospores with mean range = 8.3-8.7 X 5.4-5.7 µm.......... Humidicutis poilena

13. (11) Pileus and stipe dark grey to black overall.......... Hygrocybe waolipo
13. Pileus and stipe red, orange or yellow.......... 14

14. Pileus and stipe deep red to reddish orange; basidiospores with mean width range = 3.9-4.7 µm.......... Hygrocybe constrictospora
14. Pileus and stipe orange or yellow, lacking red tones; basidiospores with mean width range = 5.2-6.9 µm........... 15

15. Lamellae decurrent to deeply decurrent; basidiospores not constricted, mean range = 8.1-9.8 X 6.0-6.9 µm; caulocystidia common.......... Hygrocybe puaena
15. Lamellae broadly adnate, sinuate or emarginate, never decurrent; basidiospores 50-70% constricted, mean range = 7.6-8.2 X 5.2-5.3 µm; caulocystidia absent.......... Hygrocybe lamalama

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