Linocarpon arengae Konta & K.D. Hyde, in Konta, Hongsanan, Liu, Eungwanichayapant, Jeewon, Hyde, Maharachchikumbura & Boonmee, Mycosphere 8(10): 1963 (2017)

Index Fungorum number: IF 553960; Facesoffungi number: FoF 03844

Etymology – The specific epithet refers to the host genus Arenga.
Holotype – MFLU: 15–0306

Saprobic on rachis of Arenga pinnata (Wurmb) Merr. Sexual morph Ascomata 125–355 μm high × 878–1,368 μm diameter (x̅ = 205 × 1,094 μm, n = 10), solitary or aggregated, superficial, comprising black, dome-shaped, raised, blistering areas, subglobose, flattened at the base, with a central ostiole. Peridium 64–90 μm diameter (x̅ = 76 μm, n = 10), outer cells merging with the host epidermal cells, composed of dark brown to black cells of textura angularis. Hamathecium comprising numerous, 2–3.5 μm diameter (x̅ = 3 μm, n = 10), hyaline, hypha-like, septate paraphyses, longer than asci. Asci 132–177 × 9–15 μm (x̅ = 153 × 11 μm, n = 20), 8-spored, unitunicate, cylindrical, long-pedicellate, with a J-, wedge-shaped, subapical ring. Ascospores 91–102 × 2–4 μm (x̅ = 102 × 3 μm, n = 20), parallel when immature, becoming spiral when mature, filiform, straight or curved, hyaline, aseptate, containing numerous refringent septum-like bands, ends rounded, with polar mucilaginous appendage at the apex, smooth-walled. Asexual morph Undetermined.

Culture characters – Ascospores germinating on MEA within 3 days. Colonies on MEA reaching 6.5–7 cm diameter after 2 months at 25 °C, white at the edge, brown in the middle with strong radiations outwards. After 30 days of incubation, colonies smooth, hyphae septate, branched, smooth.

Material examined – THAILAND, Phang-Nga Province, on the dead rachis of Arenga pinnata (Wurmb) Merr. (Arecaceae), 5 December 2014, Sirinapa Konta, PHR07h (MFLU 15–0306, holotype); HKAS100700, isotype; ex-type living culture, MFLUCC 15–0331.

GenBank Accession numbers – SSU: MG366596.

NotesLinocarpon arengae is introduced as a new species based on the morphology and DNA sequence data. However, the species that were included in this genus are known to form a polyphyletic clade based on LSU sequence data (Bahl 2006). Furthermore, in this study, the phylogenetic analyses indicated that L. arengae is most closely related to L. cocois with good bootstrap support and was placed in the same clade with L. pandanicola and shown as a monophyletic clade within Linocarpaceae fam. nov., but it forms a distinct lineage (Table 1).

Fig 1. Linocarpon arengae (MFLU 15–0306, holotype). a Appearance of ascomata on host substrate. b, c Close up of ascoma. d Yellowish ascospore mass. e Section of ascomata. f, g Peridium. h Paraphyses. i–n asci. o J- reaction of apical ring. p–t Appendage. u–ab Ascospores. Scale bars: b = 500 μm, c–f = 200 μm, g = 20 μm, h = 10 μm, i–n, u–ab = 50 μm, and o–t = 5 μm.