Blackwellomyces roseostromatus Mongkols., Noisrip., Khonsanit & Luangsa-ard, Mycol. Progr. 19(9): 968 (2020)
Index Fungorum number: IF 835362; Facesoffungi number: FoF 13956
Parasitic on larva of insect cocoon. Sexual morphs: Stroma up to 10 mm long, yellowish orange, clavate, solitary, simple, fleshy, apically enlarged, stipitate. Stipe up to 5.6 mm long, 0.8 mm wide, cylindrical, orange. Rhizoids flexuous, multiple, arising from body of a lepidopteran larva. Fertile part up to 4.4 mm long, 1.3 mm wide, yellowish orange, clavate. Perithecia 260–370 × 140–200 (x̄ = 314× 164, n = 5) μm, semi-immersed, ovoid, spare, with periphyses, prominent ostioles. Peridium 10–20 (x̄ = 16, n = 30) μm in wide, two-layered, with the outermost layers comprised of yellow cells textura angularis, the inner layer comprised of hyaline cells of textura prismatica, the area near to ostioles encompassed by palisade cells. Asci 160–260 × 3–5 (x̄ = 204× 4.3, n = 20) μm, cylindrical, eight-spored, with thickened apex (measuring 2.4–3.5 × 1.5–2.9 (x̄ = 3× 2.2, n = 30) μm). Ascospores 140–200 × 0.8–1.5 (x̄ = 164× 1.1, n = 5) μm, hyaline, filiform, aseptate. Asexual morphs: Conidia arranged as evlachovaea-like.
Culture characteristics – Culture was obtained by cultivating a small piece of tissue isolated from fertile part of the natural specimen. Colony on PDA medium moderately growing, reaching 3.5 cm within 49 days, white, circular, velvety, producing reddish pigment diffusing in agar medium. Mycelium 1.5–2.9 (x̄ = 2.2, n = 20) μm hyaline, smooth-walled, branched, occasionally septate, guttulate. Phialides 5.5–13 × 1.2–3.5 (x̄ = 10 × 2.5, n = 20) μm, arising from procumbent hyphae, hyaline, cylindrical to flask-shaped to enlongated-ovoid, phialidic, smooth-walled, aseptate, solitary or in whorls of two. Sometimes, phialides reduce into small denticles (measuring 1–4 × 0.6–1.6 (x̄ = 2.1 × 1.1, n = 20) μm), which percurrently proliferate from the apex of cylindrical phialides or sympodially develop from flexuous hyphae. Conidia hyaline, aseptate, smooth-walled, ellipsoidal or cylindrical. Ellipsoidal conidia 4.2–5.6 × 1.5–2.2 (x̄ = 4.8 × 1.8, n = 40) μm, usually forming from cylindrical or flask-shaped or elongated-ovoid phialides as well as from small denticles, often aggregated in wheat ear-like. Cylindrical conidia 5.3–9.1 × 0.7–1.3 (x̄ = 6.6 × 1, n = 30) μm, typically produced from tip of small denticles, solitary.
Material examined – Thailand, Chiang Mai Province, Mushroom research center, on an insect cocoon bruied in soil, 12 August 2020, De-ping Wei, MRC0819 (MFLU 22-0274), living culture MFLUCC 22-0189.
Molecular data – LSU (OQ127379), SSU (OQ127309), ITS (OQ127345), TEF (OQ186371), RPB1 (OQ186425), RPB2 (OQ186399)
Notes – Blackwellomyces roseostromatus was introduced by Mongkolsamrit et al. (2020b) from a lepidopteran larva in Chiang Mai Province, Thailand. In this study, a new collection of B. roseostromatus was discovered on the pupa of an unidentified insect from the same area as the holotype (BBH 47570). Although our isolate (MFLU 22-0274) phylogenetically groups with extant strains of B. roseostromatus with significant support, it morphologically differs from the holotype in having straight, orange stipe, unbranched fertile part, spare perithecia and aseptate ascospores, as opposed to cream, slightly flexuous stipe and branched fertile part, crowded perithecia and septate ascospores. Our isolate resembles the ex-type of B. roseostromatus in producing reddish pigment diffusing in PDA media, but differs in producing synanamorphs, which have not been noted in Mongkolsamrit et al. (2020b).
Blackwellomyces roseostromatus (MFLU 22-0274) a Substrate. b, c Stroma growing from host. d Perithecia on stroma. e Peridium. f, g Vertical section through stroma showing perithecia. i Ascus cap. h, j, k Immature and mature asci. l, m Ascospores. n, o, t Conidiophores. p, q Conidiogenous cells. r, s Upper and reverse of culture. u, v Conidia. Scale bar: b = 5 mm, c = 2 mm, d, f, g = 200 μm, e, h = 30 μm, i, u, v = 5 μm, j–n = 50 μm, o–t = 10 μm. (m, o, p, q, t –v mounted in cotton blue solution).
Wei DP, Gentekaki E, Wanasinghe DN, Karunarathna SC, Tang SM, Hyde KD 2022 – Diversity, molecular dating and ancestral characters state reconstruction of entomopathogenic fungi in Hypocreales. Mycosphere 13: 281–351.