Acarospora profusa K. Knudsen, Kocourk. & Kondrysová sp. nov. Fig. 7 Type. U. S. A. • Utah, Garfield Co., Box Death Hollow Wilderness Area, east of Pine Creek Road, on Middle Jurassic - Late Jurassic HCl-sandstone escarpments above Pine Creek, 37.862, -111,631, alt. 1940 m, 20 May 2023, S. Leavitt 23203 (BRY-C-holotype), S. Leavitt 23187 (BRY-C, topotype). Diagnosis. Similar to Sarcogyne aquatica forming structures of compound apothecia but differing in forming aggregates of subdividing apothecia on a widening mycelial base, forming elevated fascicles on the end of interconnected “ stipes ” of vertical hyphae up to 0.3 mm high, continuing to replicate by division, and with up to 70 interconnected apothecia. Etymology. Named for the profusion of thin ascospores and of interconnected apothecia. Description. Thallus endolithic, algal layer below the mycelial base of apothecia, algal cells mostly 5–7 µm wide. Apothecia 0.2–1.0 mm wide. Margin with or without distinct segmented margins, round to irregular, varying in width, 30–40 (– 100 µm), outer layer black, one cell to 30–50 µm wide, inner layer hyaline, sometimes excluded. Disc black, gyrose, no umbos, epihymenial accretions 30–40 µm tall. Apothecia solitary at first but quickly replicating by division, forming elevated fascicles up to 0.3 mm high of (2 –) 10–70 apothecia. Eventually the mycelial base replicates by division, separating one aggregate of apothecia from another aggregate of apothecia. The mycelial base is filled with crystals and formed by vertical hyphae mostly 1 µm wide becoming bundles of intertwined hyphae ca. 5 µm wide, forming “ stipes ” elevating apothecia. Hymenium (80 –) 100–120 µm tall, paraphyses 1–2 µm wide, apices in black gel caps, hymenial gel IKI + blue or red (if blue, turning red in squash), hemiamyloid. Asci thin, cylindrical to inflated, 100–90 × 10–20 µm, hundreds of ascospores, 1.0 × 1.0–1.5 µm, thin ellipsoid, sometimes with oil drop. Subhymenium indistinct, to 30 µm tall, IKI + blue. Hypothecium indistinct. No pycnidia observed. Apothecia and / or epilithic thallus. producing low amounts of norstictic acid, spot test either negative or K + faint yellow mist, not producing crystals, but positive in solvents A and C. Habitat and distribution. On non-calcareous sandstone in Utah. Notes. Acarospora profusa is easily determined by the thin ascospores and the fascicles of up to 70 elevated apothecia on a mycelial base. The elevating “ stipes ” of apothecia are formed by the vertical hyphae of the mycelial base growing upward to elevate apothecia. Eventually the mycelial base splits, forming “ two islands ” of fasciculate apothecia. Though Acarospora leavittii often has dispersed apothecia, it can sometimes form similar-looking aggregates of apothecia but differs from A. profusa in not being elevated and instead being directly attached to a communal mycelial base that is dividing. Acarospora leavittii also differs in not having thin ellipsoid ascospores but globose to broadly ellipsoid ascospores that can eventually become as large as 7 × 10 µm.

Published as part of Knudsen, Kerry, Kocourková, Jana, Kondrysová, Eva, Pušová, Tereza, Hollinger, Jason, Leavitt, Steve, McCarthy, John, Jedličková, Lucie & Westberg, Martin, 2025, Discovering the diversity of Acarosporaceae (Acarosporales, Lecanoromycetes) with carbonized epihymenial accretions in North America, pp. 123-148 in MycoKeys 122 on pages 123-148, DOI: 10.3897/mycokeys.122.162675