Hemigraphaceae D.Q. Dai & K.D. Hyde, 2018

Dai, Dong-Qin, Tang, Li-Zhou, Liu, Chao, Wang, Hai-Bo & Hyde, Kevin D., 2018, Studies on Parmulariaceae I. A phylogeny based on available sequence data; introducing Parmulariales ord. nov., and Hemigraphaceae, Melaspileellaceae and Stictographaceae fam. nov., Phytotaxa 369 (2), pp. 63-79 : 67-70

Hemigraphaceae D.Q. Dai & K.D. Hyde , fam. nov.

Index Fungorum number: IF554062; Facesoffungi number: FoF 03910

Biotrophic on thallus of lichens. Sexual morph: Ascostromata solitary to gregarious, in groups, superficial, black to dark brown, coriaceous, stellate, irregularly opening from the centre to margin, conical in section. Peridium composed of two parts; outer part, a black layer, composed of thick-walled cells of textura angularis ; inner part thin, composed of light brown cells of textura angularis . Hamathecium composed of a few brown, unbranched, filamentous, septate, pseudoparaphyses around asci. Asci 8-spored, bitunicate, clavate to cylindric-clavate, subglobose, with an ocular chamber and a short pedicel. Ascospores 3-seriate to irregularly arranged, brown, ellipsoid, 1-septate, with larger upper cell and narrower lower cell, smooth-walled. Asexual morph: Undetermined.

Type genus: Hemigrapha (Müll. Arg.) R. Sant. ex D. Hawksw., Kew Bull. 30(1): 9 (1975)

Notes:—The genus Hemigrapha , typified by H. asteriscus (Müll. Arg.) R. Sant. ex D. Hawksw (Basionym: Melanographa asteriscus Müll. Arg. ), was introduced by Hawksworth (1975). This genus is a communalistic taxon having a biotrophic life-style ( Diederich & Wedin 2000, Ertz & Diederich 2015). Inácio & Cannon (2008) revised the genera of Parmulariaceae but did not include Hemigrapha in the family. However, Lumbsch & Huhndorf (2010), Hyde et al. (2013) and Wijayawardene et al. (2014) included this genus in Parmulariaceae . The lichenicolous fungi, Hemigrapha is similar to Viegasella ( Tian et al. 2015) in having star-shaped ascomata, but differs in its smooth-walled ascospores ( Viegasella has verrucose ascospores). Hemigrapha is characterized by dark, superficial, star-shaped ascomata forming on a thallus of lichens, clavate to subglobose asci and brown, ellipsoid, 2-celled ascospores ( Diederich & Wedin 2000). Based on the morphology of the re-examined type in this paper, Hemigrapha is not similar with the family type of Parmulariaceae . Ertz & Diederich (2015) included H. atlantica in their phylogenetic analysis and indicated that this genus belongs to order Asterinales based on LSU sequence data, without assigning the family placement. In this study, Hemigrapha atlantica Diederich & Wedin forms a single clade clustering within the order Asterinales ( Fig. 1 ). Hemigrapha atlantica phylogenetically forms as a sister species with the generic type H. asteriscus , seen in Ertz & Diederich (2015). Therein a new family Hemigraphaceae is introduced to accommodate this single genus in Asterinales .

Type species: Hemigrapha asteriscus , Figure 2 .

Facesoffungi number: FoF 02312

Basionym: Melanographa asteriscus Müll. Arg. , Flora, Regensburg 65(33): 519 (1882)

Syntype:—G 00292584

Biotrophic on lichens. Sexual morph: Ascostromata 1–1.5 mm diam., solitary to gregarious, in groups, superficial, black to dark brown, coriaceous, stellate, irregularly opening from the centre to margin, conical in section, 50–115 μm diam., 30–55 μm high. Peridium 7–10 μm thick, composed of two layers; outer part, black, composed of thick-walled cells of textura angularis ; inner part thin, composed of light brown cells of textura angularis . Hamathecium composed of few brown, unbranched, 1–1.5 μm wide, filamentous, septate, pseudoparaphyses around asci. Asci 19–30 × 8–15 μm (= 24.4 × 10.9 μm, n = 20), 8-spored, bitunicate, clavate to cylindric-clavate, subglobose, with an ocular chamber and a short pedicel. Ascospores 8.5–12.5 × 3–4 μm (= 10.1 × 3.7 μm, n = 20), 3-seriate to irregularly arranged, brown, ellipsoid, 1-septate, with large upper cell and narrower lower cell, smooth-walled. Asexual morph: Undetermined.

Material examined:— AUSTRALIA, New South Wales, Mount Kosciuszko, on thallus of Peltigera dolichorrhiza (Lichen) . Müller J. 1882 (G 00292584, syntype).

Figures

FIGURE 1. Maximum likelihood phylogenetic tree generated by RAxML (GTR+G model) based on analysis of combined LSU and SSU sequence data. ML values (>50 %) resulting from 1000 bootstrap replicates and Bayesian posterior probabilities greater than 0.80 are given at the nodes. The strain numbers are noted after the species names. The tree is rooted to Dendrographa decolorans (DUKE 0047570).

FIGURE 2. Hemigrapha asteriscus (G 00292584, syntype). a. Herbarium material. b–d. Appearance of ascostromata on host surface. c, d. Ascostromata in the water. e–j. Section of ascostroma. h. Asci with hamathecial tissues. i–m. Asci. n, o. Ascospores. Scale bars: a = 20 mm, b–d = 500 μm, e–g = 50 μm, h–o = 5 μm.