Hysterodifractum partisporum D.A.C. Almeida, Gusmão & A.N. Mill., 2014

Hysterodifractum partisporum D.A.C. Almeida, Gusmão & A.N. Mill. View in CoL , sp. nov. MycoBank MB 807161 ( Fig. 3 View FIGURE 3 )

Hysterodifractum partisporum is comparable to Actidiographium orientale ( Vasilyeva 2000: 5) , but differs by unbranched hysterothecia that are not densely aggregated and by ascospores disarticulating into part-spores.

Etymology:— Refering to the ascospores disarticulating into part-spores.

Type:— BRAZIL. Paraíba: Areia, Mata do Pau-Ferro State Ecological Reserve (6º58’14”S, 5º44’55”W), on twig of unidentified plant, 8 November 2011, D.A.C. Almeida s.n (holotype HUEFS 42865 GoogleMaps , isotype ILLS 71163 GoogleMaps ).

Hysterothecia superficial, black, carbonaceous, navicular, straight or sometimes flexuous, with a longitudinal slit, sulcus shallow, slightly striated laterally to smooth, gregarious, lying at irregular angles, 0.3–1.5 mm long × 0.2–0.3 mm high × 0.2–0.4 mm wide. Pseudoparaphyses hyaline, aseptate, apically branched, forming an epithecium above the asci, 1–2 µm wide. Asci bitunicate, cylindrical to clavate, 8-spored, uniseriate to partially biseriate, 77–115 × 4.5–8.5 µm. Ascospores pale brown, fusiform, smooth, straight, disarticulating into 16 partspores; part-spores ovoid or obovoid, 1-septate, 5–7.5 × 2.5–4 µm. Anamorph unknown.

Notes:— Hysterodifractum has the typical thick-walled, carbonaceous, navicular hysterothecium found in Hysteriaceae , but can be distinguished from all accepted genera in this family by the ascospores disarticulating into part-spores when mature. This is the first report of part-spores occurring in a hysteriaceous fungus.

Molecular analysis

The original LSU alignment comprised 123 taxa and 1,393 bp positions. After using Gblocks to remove ambiguous regions from the sequence alignment the final dataset consisted of 1,253 bp. PHYML analyses produced a single most likely tree ( Fig. 4 View FIGURE 4 ). Molecular analyses based on LSU sequence data indicate that these species found in the Brazilian semi-arid region occur in two distinct orders, Hysteriales and Pleosporales . Anteaglonium brasiliense occurred in a strongly supported clade with all other species of Anteaglonium in the Pleosporales (≥ 95% BPP, 97% BS). Graphyllium caracolinense occurred as a well-supported sister clade to Oedohysterium (≥ 95% BPP, 88% BS) in the Hysteriaceae . Hysterodifractum partisporum grouped within Hysteriaceae with high Bayesian PP value (≥ 95%) but without significant BS support. The Brazilian isolate of Rhytidhysteron rufulum clustered in a highly supported clade (≥ 95% BPP, 79% BS) with all other isolates of R. rufulum from Europe, Ghana and Kenya.