Rhopalostroma D. Hawksw., Kew Bull. 31(3): 422 (1977)

Index Fungorum number: IF 4722; MycoBank number: MB 4722; Facesoffungi number: FoF 03002; 11 morphological species (Species Fungorum 2020), 4 species with sequence data.

Type species – Rhopalostroma indicum D. Hawksw. & Muthappa

Notes – Rhopalostroma species are characterized by pedicellate, melanized stromata with often abruptly expanded convex heads. The globose to subglobose stromatal morphology of Rhopalostroma is close to Phylacia. Rhopalostroma possesses a single layer of ascomata in the stroma, asci with apical ring and ascospores with a germ slit, which differs from Phylacia with multilayers and compact ascomata in the stroma, lack of ascal apical ring and lack of germ slit in the ascospores. Rhopalostroma species are restricted to subtropical Africa and South Asia. Based on morphological affinities with Thamnomyces and Phylacia, phylogenetic analyses and secondary metabolite profiles, the genus is accepted in Hypoxylaceae (Hawksworth 1977, Stadler et al. 2010, Daranagama et al. 2014, 2018, Wendt et al. 2018).

A key to the species of Rhopalostroma
1. Ascospores greater than 12 μm long ………………………………………………….. 2
1. Ascospores less than 12 μm long ……………………………………………………….. 4
2. Stromata 8-12 mm tall; ascospores (13-) 14-16 x 6-7 (-9) μm;
on Bombaceae; Sierra Leone, Ghana, Nigeria, Zaire and
Angola ………………………………………………………………………………. R. angolense
2. Stromata 3-5 mm tall ……………………………………………………………………….. 3
3. Ascospores (10-) 14-16/4-5 (-6.5) μm; on dead wood;
Sri Lanka …………………………………………………………………. R. sphaerocephalum
3. Ascospores 12-15 x 6-8 μm; on Ficus; India …………………… R. hawksworthii
4. Stromata greater than 8 mm tall ………………………………………………………… 5
4. Stromata less than 8 mm tall …………………………………………………………….. 7
5. Ascospores 9-11.5 x 4.5-7 μm; stromata 8-16 mm tall; on dead wood;
Thailand …………………………………………………………………………………… R. gracile
5. Ascospores less than 9 μm long ………………………………………………………… 6
6. Ascospores (6-) 7-8.5 (-9) x (2.5-) 3-5 μm; stromata 10-15 mm tall;
on Artocarpus integrifolia; India ……………………………………………… R. dennissii
6. Ascospores (7-) 7.5-8.5 (-9) x4-5 μm; stromata 7-20 mm tail;
India ………………………………………………………………………………………. R. indicum
7. Stromata very small, up to 3.5 mm tall ………………………………………………. 8
7. Stromata larger, up to 8 mm tall ………………………………………………………… 9
8. Ascospores 8.5-10 × 3.5-5 μm; stromata 2-3.5 mm tall; on dead wood;
Thailand ………………………………………………………………………………….. R. kanyae
8. Ascospores 10-12 x 4-6 μm; stromata up to 2.5 mm tail; on dead wood;
India …………………………………………………………………………… Rhopalostroma sp.
9. Ascospores 7.5-10×3.8-5 μm; stromata up to 8 mm tall; on dead wood;
Thailand ……………………………………………………………………………………. R. lekae
9. Ascospores mainly exceeding 9 μm or greater in length …………………….. 10
10. Ascospores 9-11 x 3-4.5 μm; on dead wood; Philippine
Islands ……………………………………………………………………………….. R. tuzonense
10. Ascospores 9-10.5 x (3.5-) 4-5 (-6) μm; on dead wood;
Uganda ………………………………………………………………………………. R. africanum

Species