Coniarthonia megaspora Aptroot, Mendonça & M. Cáceres, 2015

Aptroot, André, Ertz, Damien, Silva, Jeanne Dos Reis, Grube, Martin & Cáceres, Marcela Eugenia Da Silva, 2015, The phylogenetic position of Coniarthonia and the transfer of Cryptothecia miniata to Myriostigma (Arthoniaceae, lichenized ascomycetes), Phytotaxa 218 (2), pp. 128-136 : 130

Coniarthonia megaspora Aptroot, Mendonça & M. Cáceres , sp. nov. ( Fig. 1 )

Mycobank #811664

Corticolous Coniarthonia similar to C. pulcherrima but with ascospores 23–26 × 9–10 μm, hyaline but becoming violet in tap water after the hamathecium is squashed.

Type: — BRAZIL. Sergipe: Parque Nacional Serra de Itabaiana, S slope ; alt. c. 400 m; on bark of tree; 10 May 2014, M.E.S. Cáceres, C. Mendonça & A. Aptroot 21759 (holotype ISE!; isotype ABL!) .

Thallus spreading, covering an area of up to 5 cm diam., brown to dark brown, very thin and mostly visible near the ascomata, dull, without prothallus. Algae trentepohlioid. Apothecia irregular in outline with linear or branched shapes, only slightly raised above the thallus, 0.2–0.6 mm diam., occasionally confluent, dark pink throughout, without differently coloured pruina, margins not differentiated. Excipulum not developed. Epihymenium blood red. Hymenium without gel, IKI+ blue, hyaline with red streaking; paraphysoids anastomosing. Asci ellipsoid, IKI-negative, dispersed in the hymenium, 63–76 × 20–26 μm diam, wall c. 5 μm. Ascospores 8/ascus, hyaline but becoming violet in tap water when squashing a section, probably by taking up one of the pigments of the hamathecium, clavate, 1-septate, 23–26 × 9–10 μm, slightly constricted at the septum, ends broadly rounded, wall and septum c. 1 μm thick. Pycnidia not observed.

Secondary chemistry: —Apothecia UV-, C-, P-, K+ purple red, pigment dissolving and colour becoming orange before vanishing. TLC: chiodectonic acid.

Ecology and distribution: —On smooth bark of trees in primary Atlantic rain forest. Known only from Brazil.

Remarks: —This species differs from other Coniarthonia species by large, 1-septate ascospores; see key below.

Figures

FIGURE 1. Coniarthonia megaspora, isotype (ABL). A. habitus. B. ascospores. C. asci. D. section through apothecium. Scale: A = 0.5 cm, B = 10 μm, C = 20 μm, D = 50 μm.