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

Figs 6 , 8 g

Etymology.

australiensis referring to the species being found in Australia.

Type.

AUSTRALIA • Queensland, Tablelands, Mareeba, Barron Gorge National Park, Wright’s Lookout , 18.8401°S, 145.6427°W, ca 367 m, 4 Feb 2006, T. W. Osmundson 1080 ( Holotype: BRI AQ 0796293 , Isotype: NY 2049854 ) .

Diagnosis.

Abtylopilus australiensis differs from other species of Abtylopilus in its reddish-brown pileus, reddish to orange-red hymenophore staining dark red initially then blackish when bruised, orange-red, brownish red to blackish stipe, and a trichoderm pileipellis composed of 3–4 μm wide vertically arranged to slightly interwoven hyphae.

Description.

Basidiomata medium to large sized. Pileus 3.4–5.6 cm in diameter, convex to plane; surface subtomentose, dry, reddish brown (7 E 7-7 F 7); context whitish, staining dark red at first, and then becoming black when injured. Hymenophore depressed around apex of stipe; surface cream (4 A 3-4 A 4) to reddish (6 A 3-6 A 4), becoming orange-red (7 A 6-7 A 7) in age, staining dark red initially then blackish when bruised; pores nearly round, 0.3–1 mm wide, pale cream (4 A 2), becoming pale pinkish brown (7 D 5) to nearly black (4 F 6) in age; tubes up to 4 mm long, concolorous with hymenophoral surface. Stipe 4–5.9 × 0.7–1.1 cm, equal, solid, cream (4 A 2) to yellowish (4 A 4) when young, orange-red (7 A 6) to brownish red (7 D 8) at apex and reddish brown (6 D 8-6 E 8) to blackish (4 F 6) downward when mature; surface densely covered with minute-pruinose squamules; context whitish, staining dark red at first, and then becoming black when injured.

Basidia 25–30 × 8–12 μm, clavate to narrowly clavate, thin-walled, 4 - spored, hyaline to yellowish in KOH. Basidiospores [60 / 2 / 1] (8.0) 8.5–10.5 (11) × (3.0) 3.5–4.5 (5) μm [Q = (1.78) 2.11–2.86 (3.17), Q m = 2.47 ± 0.23], subcylindrical or subfusiform and inequilateral in profile view with slight suprahilar depression, oblong to fusiform in ventral view, smooth, yellowish to brownish in KOH, yellow to yellow-brown in Melzer’s reagent. Hymenophoral trama boletoid; hyphae cylindrical, hyaline to yellowish in KOH, yellowish to yellow in Melzer’s reagent. Cheilocystidia 45–56 × 12–13 μm, broadly subfusiform to fusoid-ventricose, thin-walled, yellowish to brownish in KOH, yellow to yellow-brown in Melzer’s reagent; surface without encrustations. Pleurocystidia morphologically similar to cheilocystidia. Pileipellis a trichoderm, composed of 3–4 μm wide vertically arranged to slightly interwoven hyphae, yellowish brown to brown in KOH and yellow-brown to dark brown in Melzer’s reagent; terminal cells 17–27 × 2–3 μm, subfusiform to cystidioid. Pileal trama composed of thin-walled hyphae; hyphae 2.5–4 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 soil in rainforest; currently known in Australia.

Notes.

Abtylopilus australiensis is characterized by its reddish-brown pileus; white context staining dark red at first and then becoming black when injured; reddish to orange-red hymenophore staining dark red initially and then blackish when bruised; orange-red, brownish red to blackish stipe; smooth basidiospores; and trichoderm pileipellis. Phylogenetically, Ab. australiensis clusters with Ab. scabrosus and forms a sister group with Ab. indonesiensis , and they are morphologically similar to each other. However, Ab. scabrosus differs from Ab. australiensis in its grayish red to brownish red pileus covered with tomentose squamules; gray to grayish pink hymenophore; white to dingy white stipe covered with dark scabrous squamules; and relatively large basidia measuring 28–55 × 16–17 μm ( Li and Yang 2021). Abtylopilus indonesiensis differs from Ab. australiensis in its chocolate-brown to black pileus, pinkish hymenophore, pinkish orange stipe that is deep purple to black toward the base, and relatively small basidia measuring 26–40 × 10–11 μm ( Li and Yang 2021).

Figures

Figure 6. Microscopic features of Abtylopilus australiensis (NY 2049854, type). a Basidiospores b Basidia and pleurocystidium 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/).