Halorosellinia rhizophorae Dayarathne, Jones E.B.G.& K.D. Hyde, sp. nov.
Index Fungorum number: IF 551858, Facesoffungi number: FoF 01811, Fig. 1
Etymology – Name referring to the host genus Rhizophora.
Holotype – MFLU 15–0183
Saprobic on dead root of Rhizophora sp. submerged in marine habitats. Sexual morph Pseudostromata 1.5 – 2.5 × 0.9 – 1 mm (x̄ = 2 × 0.8 mm; n = 10), semi-immersed, pulvinate to hemisphaerical, in clusters of up to 20 uni peritheciate pseudostromata, surface black, carbonaceous, lacking ascomatal projections. In section pseudostromata comprises host cells, filled with amorphous black fungal material. Ascomata 350 – 380 × 96 – 114 μm (x̄ = 365 × 105 μm; n = 10), immersed in pseudostroma, subglobose to hemisphaerical, black, ostioles papillate. Peridium 25 – 38 μm wide, two-layered, outer layer of cells of textura angularis, black, fusing at the outside with the pseudostromata, inner layer of elongate cells, dark brown to black. Paraphyses 1– 3 μm wide, hyaline, abundant, persistent, aseptate. Asci 165 – 270 × 12 – 18 μm (x̄ = 217.5 × 15 μm; n = 20), overlapping, 6 – 8-spored, cylindrical, long pedicellate, unitunicate, with J+, rectangular apical ring. Ascospores 24 – 36 × 10 – 15 μm (x̄ = 30 × 12.5 μm; n = 20) overlapping uniseriate, light brown when immature, dark to opaque brown when mature, more or less equilaterally ellipsoid, ventral side varying in degree of convex curvature, upper end broadly rounded, lower end slightly pointed, 1-celled, 1– 2-guttulate, without appendages, germ slit on the ventral side, straight, ¾ total length of spore. Asexual morph Undetermined.
Culture characteristics – Colonies on PDA at 25 – 28 °C reaching 5 cm in 7 days, whitish, zonate with diffuse margins, reverse at first whitish and turning light brown after 3 – 4 days.
Material examined – THAILAND, Krabi Province, Krabi, 8°25′52″ N, 98°31′42″ E, 0 m asl., on submerged root of Rhizophora sp., 7 December 2014, Monika Dayarathne, KRB018 (MFLU 15–0183, holotype, HKAS 92496 isotype); ex-type living culture, MFLUCC 15–1281, KUMCC 16-0004.
Notes – Distinctive features of Halorosellinia include a poorly developed pseudostromata which lack extractable pigments in KOH, asci with a relatively large apical apparatus, that become dark blue in Melzer’s reagent and ascospores with a prominent, straight germ slit on the ventral side (Whalley et al. 1999). The new species, Halorosellinia rhizophorae is clearly different from the type, Halorosellinia oceanica (S. Schatz) Whalley et al. in lacking ascomatal projections (Table 1). They are approximately similar in ascospore morphology being 1-celled, light brown to opaque brown, more or less equilaterally ellipsoid, with the ventral side varying in the degree of convex curvature, the upper end broadly rounded, lower end slightly pointed, and with 1 – 2 guttules. A Geniculosporium-like asexual morph was reported from the ex-type culture of H. oceanica (Whalley et al. 1999). However, an asexual morph was not found associated with H. rhizophorae on host substrate or in culture media. Halorosellinia rhizophorae also has morphological affinities to Nemania maritima having more or less inequilaterally ellipsoid ascospores with germ slits. However, ascospores of H. rhizophorae are larger than that of N. maritima [9 – 12 × 5 – 6(–6.5) μm]. When considering the differences between these taxa, in H. rhizophorae the ascomata are immersed in a pseudostroma, asci have a long stipe with a well-developed apical ring. In N. maritima ascomata are aggregated and submerged in the carbonaceous stroma and asci are short-stalked. Maximum likelihood analysis of combined ITS and LSU sequence data confirmed the placement of H. rhizophorae within the family Xylariaceae, where it forms a sister clade to the type, H. oceanica with 81 % bootstarp support (Fig. 78). However, H. rhizophorae is distantly placed from Nemania spp. in the phylogenetic analyses.
Fig. 1 Halorosellinia rhizophorae (holotype) a, b Appearance of pseudostromata on host b Horizontal section through pseudostroma c Section through pseudostromata d Peridium e Apical apparatus stained blue in Melzer’s reagent f – h Asci i Paraphyses j – m Ascospores. Scale bars: b = 200 μm, c = 100 μm, d, e = 20 μm, f – i = 50 μm, j – m = 20 μm.
