オリーブニガイグチ

Tylopilus neofelleus f. olivaceus Har. Takah., Trans. Mycol. Soc. Japan 27(1): 95 (1986)

傘が黄味がかったくすんだ黄緑色(olive yellow)を帯びる ニガイグチモドキの一型です。東京、神奈川、長野のサンプルに基づきニガイグチモドキの1品種として記載されました。

形質の安定性にやや疑問があり、T. neofelleus の一時変異として扱うのが妥当かもしれません。ちなみに、オリーブニガイグチについて本郷先生はオクヤマニガイグチ(Tylopilus rigens Hongo)に似ていると仰っておられました。 

Tylopilus neofelleus Hongo, J. Jap. Bot. 42: 154. 1967.

　forma olivaceus H. Takahashi, Trans. mycol. Soc. Japan 27(1) : 95-97, 1986.

A typo differt pileo olivaceo (2E8-3E8)* dein olivaceo-brunneo (5E5-5E8).

Pileus 4-12 cm broad, convex to plano-convex, with incurved margin when young; surface dry, minutely tomentose, when young evenly colored olive (2E8-3E8), at last yellowish brown (5E5-5E8). Tubes 4-14 mm deep, depressed around the stipe, at first whitish then pinkish; pores minute, 2 to 3 per mm, subangular, when young whitish then greyish ruby (12E4) to greyish Magenta (13E4). Stipe 4-10 cm long, 1-2.5 cm thick, subequal or slightly thickened toward the base, solid; surface reddish brown (8E6-8F6), paler or whitish at the apex, minutely reticulated on the extreme apex; basal mycelium white. Flesh firm, thick, white, unchanging when injured; odor slight, taste bitter.

Basidiospores 6.5-9 x 4-5 μm, with or without a slight suprahilar depression in profile, elliptic to subfusoid, smooth, thin-walled, melleous in KOH. Basidia 25-40x7-10 μm, 4-spored. Cheilocystidia 20-50×4-6 μm, subcylindrical to subfusoid with an acute or obtuse apex, thin-walled, pale yellow in KOH. Pleurocystidia similar to the cheilocystidia. Hymenophoral trama bilateral of the Boletus-subtype. Pileal surface a trichodermium, composed of interwoven, cylindric umbrinous hyphae, 25-40×4.5-6μm, end cells cylindrical to subfusoid with an acute apex, thin-walled. Caulocystidia 20-40×4-6 μm, subcylindrical to subfusoid with an acute apex, thin-walled, pale yellow to pale brownish in KOH. Clamp connections absent.

Habitat: Solitary on the ground under Quercus serrata Thunb. and Quercus acutissima Carruthers, Mt. Jinba, Tsukui-gun, Kanagawa, Aug. 12, 1981 (TUAT 88); under Pinus densiflora Sieb. et Zucc. and Q. serrata, Mt. Omine, Nagano-shi, Nagano, Aug. 4, 1983 (TUAT 195); under Q. serrata, Q. acutissima, Abies firma Sieb. et Zucc. etc., Mt. Takao, Hatiozi-shi, Tokyo, July 30, 1984 (TUAT 242, holotype).

Distribution: Japan (Tokyo, Kanagawa, Nagano).

This fungus agrees with the Hongo's original description of T. neofelleus except for the color of its pileus. In appearance it closely resembles Tylopilus rigens Hongo (Hongo, 1979), but that species differs mainly in having much longer basidiospores of (7.5-)8.5-14(-19)×(3-)3.5-4.5(-5.8) μm.

Literature cited

Hongo, T. 1967. Notes on Japanese larger fungi (19). J. Japanese Bot. 42: 151-159.

＿＿＿＿＿. 1979. Notes on Japanese larger fungi (22). J. Japanese Bot. 54: 301-310.

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* Color notations are from Kornerup and Wanscher, "Methuen Handbook of Colour," 2nd ed., London (1967).