Mendogia diffusa Thiyagaraja, Ertz, Luecking , Samarak. and K.D. Hyde, 2021

Thiyagaraja, Vinodhini, Luecking, Robert, Ertz, Damien, Samarakoon, Milan C., Wanasinghe, Dhanushka N., Karunarathna, Samantha C., Cheewangkoon, Ratchadawan & Hyde, Kevin D., 2021, Mendogia diffusa sp. nov. and an updated key to the species of Mendogia (Myriangiaceae, Dothideomycetes), Biodiversity Data Journal 9, pp. 67705-67705 : 67705

Mendogia diffusa Thiyagaraja, Ertz, Luecking, Samarak. and K.D. Hyde sp. nov.

Materials

Type status: Holotype. Occurrence: recordedBy: Milan C. Samarakoon; occurrenceID: MFLU 20-0541; Taxon: kingdom: Fungi; phylum: Ascomycota; class: Dothideomycetes; order: Myriangiales; family: Myriangiaceae; genus: Mendogia; specificEpithet: diffusa; scientificNameAuthorship: Thiyagaraja, Ertz, Lücking, Samarak. and K.D. Hyde; Location: continent: Asia; country: Thailand; stateProvince: Phayao; locality: Phu Sang ; Identification: identificationID: MFLU 20-0541; identifiedBy: Vinodhini Thiyagaraja; dateIdentified: 4 Dec 2018; Record Level: modified: 4 December 2018; institutionID: MFLU; institutionCode: Mae Fah Luang University

Description

Saprotrophic on dead leaves. Thallus absent (Fig. 1 and Fig. 2 ). Sexual morph: Ascomata scattered in dense, pseudostromatic, irregularly stellate groups over an effuse, thallus-like, dark structure, with thin covering layer, superficial, solitary or gregarious, easily removed from the host surface, carbonaceous, ovoid to sub-globose, black, abundant, with numerous external dark brown setae on the epithecium, which are branched at the end, individual loci (120-)225-410 µm wide, 250-180 µm high. Epithecium 16-33 µm thick, distinct, dark brown. Hymenium 40-95 µm high, hyaline. Hypothecium 35-75 µm thick, distinct, thicker in the centre, brownish, infrequently with free-living unicellular algae below the hypothecium. Excipulum inconspicuous. Paraphysoids 1.1-3.3 µm thick, abundant, anastomosing, branched, not or slightly enlarged at the apex. Asci 45-70 × 25-35 µm (x¯ = 57.5 × 30 µm, n = 20), 8-spored, bitunicate, fissitunicate, ovoid to clavate, tholus thickened, tip blunted, with poorly developed stipe, ascus wall apically thickened with well-developed ocular chamber, concave. Ascospores 15-25 × 6-10 µm (x¯ = 20 × 8 µm, n = 20), irregularly arranged, hyaline, oblong to elliptical, both ends bluntly tapered, muriform, with 5-6 transverse septa, 3-6 longitudinal septa, slightly constricted at each septum, smooth-walled, without gelatinous sheath, occasionally asymmetrical. Hymenium I-, KI-, Asci I-, KI-. Asexual morph: Undetermined.

Etymology

Referring to the morphology of the fungus with ascostromata that are diffuse and spread extensively on the leaves.

Distribution

Habitats and Distribution

On dead leaves of Fagales sp. Thus far, only known from Thailand, Phayao Province, Phu Sang District.

Notes

Mendogia diffusa is the first reported species in the genus from dead dicotyledonous leaves. Other species were mostly reported from bamboo culms, with the exception of M. manaosensis that is reported from palm leaves ( Vitória 2012, Dai et al. 2017) and M. philippinensis (= M. calami ) that is found on living leaves of Calamus palms ( Jiang et al. 2020). In those species, ascostromata do not penetrate the leaf surface and they also differ from M. diffusa in the sharply delimited ascostromata; and M. philippinensis further differs in the smaller ascospores. The new taxon shares morphological characteristics with Mendogia bambusina : carbonaceous peridium, paraphysoid-like filaments, similar asci and ascopores. However, M. diffusa differs in the absence of ascostromata, presence of setae ( Dai et al. 2017), the type of habitat ( Fagales leaves vs. bamboo or palms culms) and its distribution (Thailand vs. Indonesia) ( Hyde et al. 2013, Dai et al. 2017).

Figures

Figure 1. Mendogia diffusa (MFLU 20 - 0541) a, b, d-l. Ascomata on upper leaf surface; c. Ascomata on lower leaf surface; arrows point the algae. Scale bars: b = 1000 µm, g-j = 500 µm

Figure 2. Mendogia diffusa (MFLU 20 - 0541, holotype) a-e. Vertical sections of ascomata in water (upper surface); f. Vertical section of an ascoma in water (lower surface); fh, hair-like structure on leaf; g. Ascomata in trypan blue; h, i. (a 1, a 2) Algae; j. Paraphysoids in water; k-m. Asci in water; n. Asci in 5 % KOH stained with Lugol's solution; o 1 - o 8. Ascospores in water. Scale bars: (a-g) = 200 µm, (h-j) = 5 µm, (k-n) = 30 µm, (g-j) = 30 µm, (o 1 - o 8) = 10 µm