Guestia gonetropospora G.J.D. Sm. & K.D. Hyde, Fungal Diversity 7: 109 (2001)

Index Fungorum number: IF 484503, Facesoffungi number: FoF 03044

Saprobic on dead rachis of Mauritia flexuosa L.f. Sexual morph: Pseudostromata 700–900 × 400–450 µm, erumpent, conical shaped, raised top, black, multi-loculate (1–4), solitary or clustered. Ostioles papillate, protruding through the cracks from the host, star-shaped. Ascomata 600–650 µm diam., compressed globose-globose, immersed in stromal tissue. Peridium 50–60 µm thick or more, several cell layers, composed of outermost dark brown cell layers and inner cell layers light brown, thick-walled. Paraphyses 4–6 µm wide at the base, numerous, filamentous, almost the same length as asci, septate, embedded in a gelatinous matrix. Asci 100–130 × 8–12 µm, 8-spored, unitunicate, cylindrical, tapering, short-pedicellate, with a 5–7 × 2–3 µm, barrel-shaped, J+, apical ring, bluing in Melzer’s reagent. Ascospores 22–36 × 4.5–7.5 µm, overlapping uniseriate, unicellular, inequilaterally fusoid, dark brown, with straight, full-length, germ slit, in the flattened side, inconspicuous mucilaginous sheath present, no appendages observed.

Material examined – ECUADOR, Oriente, Napo Province, Rio Cuyabeno, Cuyabeno Rain Forest, on dead rachis of Mauritia flexuosa (Arecaceae), Aug. 1993, K.D. Hyde (HKU (M) 3347, holotype).

Notes – Although originally deposited at HKU, the specimen is now housed at IFRD. The holotype material is in poor condition and has ruptured along the rachis. The asci were rarely observed after several attempts. Few immature asci were observed with the massive apical ring in Melzer’s reagent, which is also present in genera such as Rosellinia and Xylaria.

Fig. 1. Guestia gonetropospora (holotype). a Herbarium details. b Stromata in wood. c Side view of stromata d Cross section of stroma showing ascoma encased in stromal tissue. e Peridium. f Apical ring bluing in Melzer’s iodine reagent. g, h Mature ascospores (germ slit shown by arrow). i Asci. Scale bars: b = 500 µm, c = 200 µm, d = 500 µm, e = 50 µm, f =5 µm, g–i = 20 µm.