Arthoniaceae with reddish, K + purple ascomata in Japan Author Frisch, Andreas Department of Ecology, Swedish University of Agricultural Sciences, P. O. Box 7044, 750 07 Uppsala, Sweden. Author Grube, Martin Author Kashiwadani, Hiroyuki Author Ohmura, Yoshihito text Phytotaxa 2018 2018-06-13 356 1 19 33 http://dx.doi.org/10.11646/phytotaxa.356.1.2 journal article 10.11646/phytotaxa.356.1.2 1179-3163 13706056 Arthonia sanguinaria Frisch & Y. Ohmura sp. nov. MycoBank MB823125 Diagnose .—This species differs from the similar A. meissneri Müll. Arg. by the larger ascospores (15–21 × 5–8 μm, 4–5-septate vs 10–14 × 4.5–5.5 μm, 2-septate). Arthonia picea Vain. has thick-walled ascospores, 26–35 × 9–12 μm, turning brown with granular ornamentation in the perispore at late maturity, and a different chemistry (pigments A4, A5, A6). Arthonia ferruginea Vainio (1890: 165) has a distinct K+ blue pigment in the ascomata and slightly larger ascospores (20–24 × 5–8 μm, 5-septate). Etymology .—The new species is named after the blood red colour of the ascomata. Type.— Japan , Ogasawara Islands ( Tôkyô Metropolis): Chichi-jima, Mt Tsutsuji ( 27°03′33.7″N , 142°13′15.6″E ), on bark of Livistona chinensis var. boninensis , elev. 250 m . 28. vi. 2009 , Y. Ohmura 6609 (TNS holotype ). FIG . 3C, 3D , 4C THALLUS pale olivish grey to pale buff(almost whitish),thin,matt, smooth to granular-warty, coherent to fissured-areolate, up to 0.1 mm tall, partly endophloeodal; prothallus line not observed; photobiont trentepohlioid, the cells rounded to elliptical, 6–18 × 4–8 μm, in short chains or single cells; mycobiont hyphae 1.5–2.5 μm wide, with thick (0.7–1.0 μm) walls, hyaline, weakly conglutinated; calcium oxalate crystals not observed. ASCOMATA dispersed, maculate, immersed, flat, irregularly rounded to elliptical to shortly lobed, 0.5–3.0 × 0.4–1.3 mm , often separated from the thallus by a thin fissure, margin not differentiated; disc dark red, flat, level with the thallus, epruinose; proper exciple not differentiated, the margins of the ascomata without asci and with more closely netted paraphysoids; epithecium deep orange, 7–12 μm tall; hymenium deep orange-red, 40–45 μm tall, strongly conglutinated, the asci distantly spaced; hypothecium brown to olive-brown, 15–25 μm tall, conglutinated, of short-celled, densely branched and netted prosoplectenchymatic hyphae (cells 2–5 × 0.7–1.0 μm); quinoid pigments mainly as amorphous pigmentation in the gelatinous matrix of epithecium, hymenium and hypothecium, and to a lesser degree as ca 1 μm wide granular crystals attached to the hyphal walls; paraphysoids densely branched and netted, 1.0–1.5 μm wide, somewhat wavy; paraphysoid tips only slightly widened to 1–2 μm, without pigmentation of the walls. ASCI of the Arthonia-type, with broadly triangular ocular chamber, 40– 48 × 20–24 μm (n=10), lateral walls 0.5–1.0 μm thick, base not abruptly deflected, 8-spored (spores in 2–3 irregular rows). ASCOSPORES narrow elliptical with capitate upper cell, (15.0–)16.8–19.4(21.0) × (5.0–)6.1–7.5(–8.0) μm (n=40; STDV: l=1.30, w=0.66), hyaline, 4–5-septate, slightly constricted at the septa, overaged collapsed spores with pale brownish walls lacking a clear granular ornamentation in the perispore. PYCNIDIA not observed. Chemistry.— Confluentic acid (major), ± psoromic acid (minor), pigment A7 (major) in solvents B′ and C detected by TLC. Thallus hyphae I+ pale blue, KI+ blue; ascomatal gels I dil –, I+ blue, KI+ blue; asci with small KI+ blue ring structure in the tholus; ascospore walls and septa I–, KI–. The pigments change to purple in K but do not dissolve. Ecology and distribution.— On the trunk of Livistona chinensis var. boninensis in dense humid forest. The species is known from a single locality on Chichi-jima in the Osagawara Islands. Notes.— A distinctive species with almost whitish, pale olive grey thallus, dark red maculate apothecia, and hyaline, 4–5-septate ascospores with enlarged apical cell, 15–21 × 5–8 μm. The thallus margins show a distinct but rather weak zonation of brownish pigmentation. The pigments in the apothecia dissolve in LCB with precipitation of stellate clusters of red prism-shaped crystal needles ( Fig. 4B ), a character not observed in the other species treated in this study. A. meissneri Müll. Arg. (type: G!) is a fairly similar widespread species in the tropics. The ascospores of A. meissneri , however, are distinctly smaller (10–14 × 4.5–5.5 μm, 2-septate) and this species does not contain psoromic acid. Superficial similarities also exist with the neotropical A. ferruginea Vain. (TUR-Vain 28914!, holotype ), but that species differs by a distinct K+ blue pigment in the ascomata and slightly larger ascospores (20–24 × 5–8 μm, 5- septate). Additional specimen examined: — Japan , Ogasawara Islands ( Tôkyô Metropolis): Chichi-jima, Mt Tsutsuji ( 27°03′33.7″N , 142°13′15.6″E ), on bark of Livistona chinensis var. boninensis , elev. 250 m . 19. iii. 2013 , A. Frisch 13/Jp59 (TNS).