Neopestalotiopsis rhododendronicola Chaiwan & K.D. Hyde, sp. nov.                 Fig 5

Index Fungorum number: IF 845144; MycoBank number: MB 845144; Facesoffungi number: FoF 10475;

Etymology – Name reflects the host from which the fungus was isolated.

Holotype – KUN-HKAS 123204

Saprobic on dead leaves of Rhododendron sp. Sexual morph: Undetermined. Asexual morph: Conidiomata (on PDA) 60–80 × 50–75 μm, pycnidial, cervular, applanate to disc-like, partly immersed or superficial, globose to clavate, solitary or confluent, embedded or semi-immersed to erumpent, dark brown, exuding globose, dark brown to black conidial masses , rounded to irregular in outline, glabrous, unilocular or divided into several locules by tissue cells. Conidiophores indistinct, arising from the base, hyaline, filiform to cylindrical, smooth, often reduced to conidiogenous cells. Conidiogenous cell, appeared subcylindrical, flaskshaped, hyaline, smooth, phialidic, each producing a single conidium. Conidia 20–30 × 5–7 μm (x̅ = 25 × 6 μm, n=30), subcylindrical fusoid, ellipsoid, straight to slightly curved, 4-septate, (19–28) × 5–7 μm (x̅ = 23.5 × 6 μm, n=30), μm; basal cell conic with a truncate base, hyaline, rugose and thin-walled, with constrictions at the septa, hyaline, smooth-walled; with a long, tubular base, 2 median cells subcylindrical, second cell joined to the base 10–15 μm (x̅ = 12.5 μm) long, the third cell joined to the apex 11–15 μm (x̅ = 13 μm) long; apical cell subconical with a rounded apex; apical and basal cells each with a subapical, unbranched, filiform, straight appendage; apical appendage 9–11 μm (x̅ = 10 μm), basal appendage 20–25 μm (x̅ = 22.5 μm).

Culture characteristics – Colonies grown on PDA, with an undulating edge, reached 4–5 cm in 5 days at 25 °C, mycelium superficial, branched, septate, white mycelium with aerial on the surface, and produced black spore mass.

Material examined – China, Kunming Yunnan Province; on dead leaves of Rhododendron sp. (Ericaceae), 28 July 2018, Napalai Chaiwan, KIB008 (KUN-HKAS 123204, holotype; isolate MFLU20-0046; Ex-type living culture KUNCC22-10802; isolate MFLUCC22-0004).

Notes – Neopestalotiopsis rhododendronicola is described from a Rhododendron in China. In the phylogenetic analyses, N. rhododendronicola separate in the single clade and has a close phylogenetic affiliation to be sister to N. sonneratae  (MFLUCC17-1745T, MFLUCC17-1744), N. coffeae-arabicae (HGUP4019T, HGUP4015) and N. thailandica (MFLUCC17-1730T, MFLUCC17-1731) (Fig. 2). Meanwhile, is N. sonneratae  was reported on leaf spots on Sonneronata alba L. in Thailand [21], Neopestalotiopsis thailandica was reported on leaf spots of Rhizophora mucronata Lam. in Thailand [21] and N. coffeae-arabicae were found on leaves of Coffea Arabica in China [72].

Neopestalotiopsis rhododendricola sp. nov. resembles N. thailandica in having similar conidial size [21], but the difference is that N. rhododendricola has two to three tubular appendages on the apical cell, while N. thailandica showed only one to two tubular appendages on the apical cell. Comparison of ITS sequence differences revealed 2 base pairs, comparison of TEF sequence differences revealed 15 base pairs, and comparison of TUB differences revealed 6 base pairs of N. rhododendricola and N. thailandica. Therefore, based on morphology and phylogeny, we justify the description of N. rhododendricola as a new species in the Neopestalotiopsis genus.

Fig. 1 – Neopestalotiopsis rhododendronicola (KUN-HKAS 123204). (a) The habitat of the host plant (Rhododendron sp.); (b) Pycnidia with drops of conidial exudate on the leaf surface; (c,d) colonies growing on PDA; (e,f) culture; (g–j) conidiogenous cells and developing conidia; (k–p) conidia. Scale bars: (c) 500 µm; (d) 200 µm; (h) 20 µm; (i–p) 10 µm.