Abtylopilus indonesiensis Yan C. Li, J. Li, Halling, Osmundson & Zhu L. Yang, 2025

Li, Jin, Halling, Roy E., Osmundson, Todd W., Yang, Zhu L. & Li, Yan-Chun, 2025, Global diversity of the Tylopilus alboater complex (Boletaceae, Boletales): new genus and species, and typification of the name Boletus alboater, IMA Fungus 16, pp. e 159676-e 159676 : e159676-

Abtylopilus indonesiensis Yan C. Li, J. Li, Halling, Osmundson & Zhu L. Yang sp. nov.

Figs 7 , 8 h

Etymology.

indonesiensis referring to the species being found in Indonesia.

Type.

INDONESIA • Java, Haurbentes Park , alt. ca 300 m, 6.5442°S, 106.438°E, 16 Jan 2001, Halling 8070 ( Holotype: BO; Isotype: NY 1393740 ) .

Diagnosis.

Abtylopilus indonesiensis differs from other species of Abtylopilus in its a chocolate-brown to black pileus becoming a pale pinkish brown with age, a pinkish orange stipe but deep purple to black downward, a pinkish hymenophore usually, a whitish context changing to orange-red at first and then black when injured, and trichoderm pileipellis composed of 1.5–3.5 μm wide vertically arranged hyphae.

Description.

Basidiomata medium to large sized. Pileus 4–10 cm in diameter, convex to plano-convex, subvelutinous to tomentose, dry, chocolate-brown (7 C 3-7 C 4) to black (4 F 6), fading to a pale pinkish brown; context 1–1.5 cm thick, whitish, changing to orange-red then blackish when injured. Hymenophore adnate to adnexed; surface pinkish (7 A 2-7 A 3), staining orange-red at first and then black when bruised; tubes up to 8 mm long, white initially then pinkish to flesh colored when matured, staining orange-red at first and then black when bruised; pores angular, concolorous with hymenophoral surface and staining likewise. Stipe 4–6 × 1.5–2 cm, equal, dry, subpruinose, white to pinkish orange (7 A 3-7 B 3) at apex, deep purple (13 E 5-13 E 7) to black (4 F 6) downwards, staining red initially then blackish when injured. Odor and taste mild.

Basidia 26–40 × 10–11 μm, clavate, thin-walled, 4 - spored, hyaline to yellowish in KOH. Basidiospores [60 / 3 / 1] 9.0–10.5 × 4–5 μm [Q = (1.90) 2.00–2.71 (2.86), Q m = 2.31 ± 0.22], subfusiform in profile view with slight suprahilar depression, elongated to fusiform in ventral view, smooth, slightly thick-walled (up to 0.5 μm), hyaline to yellowish in KOH, yellowish to yellowish brown in Melzer’s reagent. Hymenophoral trama boletoid; hyphae cylindrical, hyaline to yellowish in KOH, yellowish in Melzer’s reagent. Cheilocystidia 32–55 × 11–14 μm, fusiform or subfusiform, thin-walled, brownish to yellowish brown in KOH, yellow to yellow-brown in Melzer’s reagent. Pleurocystidia morphologically similar to cheilocystidia. Pileipellis a palisadoderm, composed of 1.5–3.5 μm wide vertically arranged hyphae, yellowish brown to brownish in KOH and yellow-brown to dark brown in Melzer’s reagent; terminal cells 15–35 × 2–3 μm, subfusiform to cystidioid, thin-walled. Pileal trama composed of thin-walled hyphae; hyphae 2–3 μm wide, hyaline to yellowish in KOH and yellowish to yellow in Melzer’s reagent. Clamp connections absent in all tissues.

Habitat and distribution.

Gregarious on the ground of dipterocarp forest ( Shorea , Dipterocarpus , Hopea ); currently known from Indonesia.

Notes.

Abtylopilus indonesiensis is characterized by a chocolate-brown to black pileus becoming pale pinkish brown with age; a pinkish orange stipe that is deep purple to black toward the base, staining reddish brown at first and then becoming blackish when bruised; a pinkish hymenophore usually staining reddish and then blackish when bruised; a whitish context changing to orange red at first and then black when injured; smooth basidiospores; and trichoderm pileipellis. Abtylopilus indonesiensis is phylogenetically related to Ab. scabrosus and Ab. australiensis . However, Ab. scabrosus differs from Ab. indonesiensis in its grayish red to brownish red or ruby pileus, white to dingy white stipe densely covered with dark scabrous squamules, and relatively large basidia measuring 28–55 × 16–17 μm ( Li and Yang 2021). Abtylopilus australiensis differs from Ab. indonesiensis in its reddish-brown pileus, reddish to orange-red hymenophore, and reddish brown to blackish stipe densely minute-pruinose ( Li and Yang 2021).

Figures

Figure 7. Microscopic features of Abtylopilus indonesiensis (NY 1393740, type). a Basidiospores b Basidia c Cheilo- and pleurocystidia d Pileipellis. Scale bars: 20 μm.

Figure 8. Basidiomata of “ Tylopilus alboater ” from different regions. a, b N. alboater from North America (NY 1193926, images by Halling) c, d N. atronicotianus from North America (NY 815171, images by Both) e, f Neoporphyrellus sinoalboater from China (e KUN-HKAS 145312, type; f KUN-HKAS 145313) g Abtylopilus australiensis from Australia (NY 2049854, image by Osmundson) h Ab. indonesiensis from Indonesia (NY 1393740, image by Halling) (c – h from https://sweetgum.nybg.org/science/vh/specimen-list/).