Acrocalymma medicaginis Alcorn

Acrocalymma medicaginis Alcorn View in CoL & J.A.G. Irwin, Trans. Br. mycol. Soc. 88(2): 163 (1987).

Index Fungorum IF 130085, Facesoffungi FoF07099, Fig.3 View FIGURE 3

Saprobic on dead stems of Tithonia diversifolia A. Gray. Sexual morph: Ascomata 135–180 × 155–195 µm (x̄ = 160 × 175 µm, n = 5), immersed, appearing as black spots, solitary or scattered, subglobose to obpyriform, coriaceous, dark brown, ostiolate with short papillate neck. Peridium 15–20 µm wide, consists of 4–5 layers; dark brown cells in the thick outer layer, becoming hyaline cells of textura angularis to globosa in the inner layers. Hamathecium 0.5–1.5 µm wide, cylindrical to filiform, septate, branching, pseudoparaphyses. Asci 50–80 × 8–11 µm (x̄ = 64 × 10 µm, n = 20), 8-spored, bitunicate, fissitunicate, cylindric-clavate, straight or slightly curved, with a short pedicel and an apically rounded top with ocular chamber. Ascospores 15–21 × 3–5 µm (x̄ = 19 × 4 µm, n = 40), overlapping, uni or biseriate, oblong to broadly fusiform with obtuse to slightly obtuse ends, straight or slightly curved, hyaline, smooth, uniseptate, constricted at the septum, with a hyaline gelatinous sheath at the immature stage. Asexual morph: Undetermined.

Material examined: — THAILAND. Chiang Rai Province: Nang Lae, 20°02ʹ42ʺN 99°53ʹ41ʺE, on a dead branch of Tithonia diversifolia , 6 March 2024, Gayana Oshani GO 68 ( MFLU 25-0068).

Known hosts and distribution: —Root and crown rot of Medicago sativa ( Fabaceae ) in Australia ( Alcorn & Irwin 1987, Trakunyingcharoen et al. 2014), dead stem of Chromolaena odorata ( Asteraceae ) in Thailand ( Mapook et al. 2020), dead stem of Tithonia diversifolia ( Asteraceae ) in Thailand (this study).

Notes: —Multigene phylogenetic analyses ( Fig. 1 View FIGURE 1 ) showed that our species, Acrocalymma medicaginis ( MFLU 25-0068), clustered with A. medicaginis ( MFLUCC 17-1423, MFLUCC 17-1439) isolates with 78% ML and 1.00 BPP. According to the BLASTn of ITS sequence data showed similarities to A. medicaginis ( MFLUCC 17-1423) of 98.85% similarity across 97% of the query sequence. BLASTn searches of the SSU and LSU sequence data showed that our species is 99.76% and 99.73% identical to A. medicaginis ( MFLUCC 17-1423), respectively.

Morphologically, Acrocalymma medicaginis is similar to our collection by having subglobose to obpyriform ascomata, hyaline, cylindric-clavate asci, and oblong to broadly fusiform ascospores surrounded by a hyaline gelatinous sheath ( Mapook et al. 2020). The first sexual morph of Acrocalymma medicaginis was reported on Chromolaena odorata from Thailand ( Mapook et al. 2020), whereas our new isolate was reported on fallen dead branches of Tithonia diversifolia from Thailand. Based on molecular and morphological data, we identify our isolate as A. medicaginis , and this is the first report of A. medicaginis on Tithonia diversifolia from Thailand.