Robillarda mangiferae
Robillarda mangiferae Thiyag., Wanas., Phookamsak & K.D. Hyde, in Phookamsak et al., Fungal Diversity: 10.1007/s13225-019-00421-w, [162] (2019)
Index Fungorum number: IF556210 Facesoffungi number: FoF05718
Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 250–310 µm high, 300–340 µm diam., black, pycnidial, semi-immersed to erumpent, solitary, scattered, irregular in shape, uni-loculate, glabrous, minutely ostiolate, with beak-like papilla. Conidiomata walls 8–27 µm wide, thin-walled, of unequal thickness, slightly thick at the sides, composed of two types of cell layers, inner layers comprising hyaline, flattened, pseudoparenchymatous cells of textura angularis to textura prismatica; outer layers comprising dark brown to black, thick-walled, coriaceous cells, of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5–10 × 3–7 µm (x̄ = 6.9 × 4.8 µm, n = 30), holoblastic, proliferating percurrently 1–3 times, discrete, subcylindrical to ampulliform, hyaline, aseptate, smooth-walled, arising from the inner cavity. Conidia (7.5–)10–11(–12) × (2.5–)3–4(–4.5) µm (x̄ = 10.9 × 3.5 µm, n = 50), hyaline, oblong to ellipsoidal, or subfusoid, narrower towards the basal cell, straight, (0–)1-septate, thin and smooth-walled, apical cell developed into a branched appendage; appendages 25–35 × 1–2.5 µm (x̄ = 29.3 × 1.7 µm, n = 50), dividing into 2–3 branches, straight, non- flexuous, broadly tubular, narrower towards apex, inconspicuously
septate at the apex
Culture characteristics: Colonies on PDA reaching 80–85 mm diam. after 1 week at 20–25 °C, sparse to medium sparse, circular, flat, surface slightly rough with white tufts hyphae, or small granular, edge entire, floccose, forming small, black pycnidia on colony and embedded in media agar after 3 weeks; from above, white-grey to greenish grey, from below, white to cream at the margin, radiated with pale brown to black concentric ring at the middle, white-grey at the centre; not producing pigmentation in agar.
Material examined: CHINA, Yunnan Province, Xishuangbanna, Jinghong, Nabanhe, associated with leaf blight symptom on living leaf of Mangifera sp., 21 November 2015, R. Phookamsak, XB011 (KUN-HKAS 102245, holotype), ex-type living culture, KUMCC 18–0180.
GenBank Accession No: ITS = MK353084, LSU =MK353086, SSU = MK353149.
Notes: Robillarda mangiferae resembles Robillarda species in having oblong to subfusoid, septate conidia, with an apical cell modified into a branched appendage. However, R. mangiferae can be distinguished from other Robillarda species by its appendage being straight, nonflexuous, broad tubular and narrower towards the apex, with inconspicuous septa at the apex, as well as its conidiogenous cells being holoblastic and proliferating percurrently. Robillarda species have flexuous, narrow tubular, aseptate appendages and holoblastic conidiogenous cells, proliferating sympodially or percurrently near the apex (Crous et al. 2015a; Wijayawardene et al. 2016). Phylogenetic analyses of a combined ITS and LSU sequence dataset show that R. mangiferae clusters with other Robillarda species and Ellurema indica Nag Raj & W.B. Kendr. [current name = Hyalotiopsis Punith., proposed by Re´blova´ et al. (2016), and Wijayawardene et al. (2016)] in Sporocadaceae, but the species forms a distinct lineage at the base of this clade with moderate support (92% ML and 1.00 BYPP). Robillarda mangiferae differs from Ellurema indica in having oblong to ellipsoidal, or subfusoid, (0–)1-septate conidia, with straight, non-flexuous, broadly tubular apical appendages. The asexual morph of Ellurema indica (= Hyalotiopsis) has cylindrical to fusiform or obclavate conidia, with more than 1-septate and 2–3 apical bi- or tri-furcate, filiform, flexuous appendages (Wijayawardene et al. 2016, 2017a). Based on morphological characteristics and phylogenetic analyses of a combined ITS and LSU sequence dataset
(Fig. 111), we hence, introduce a new species, R. mangiferae in this study.
Figure 15. Robillarda mangiferae (KUN-HKAS 102245, holotype). a Substrate showing disease symptoms. b, c Conidiomata on substrate. d Section through conidioma. e Conidioma wall. f–h Conidiogenous cells attached to conidia. i–n Conidia. Scale bars b–d = 100 µm, e–h, i, m, n = 10 µm, j–l = 5 µm
Reference:
Phookamsak R, Hyde KD, Jeewon R, Bhat DJ (2019) Fungal diversity notes 929–1035: taxonomic and phylogenetic contributions on genera and species of fungi. Fungal Diversity 95:1–273.
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