Porina trichocoronata Debaene & Ertz 2026, sp. nov.

Porina trichocoronata Debaene & Ertz sp. nov. Fig. 13 Type. MADAGASCAR • Diego Suarez Province. Antsiranana, Region: Diana, District: Diego II, Commune: Joffreville, Forontany: Morafeu, National Park of Montagne d’Ambre, Gîte des Roussettes, mixed open woodland, around house and picnic area, 12°31'37"S, 49°10'18"E, alt. 1068 m, 6 Oct. 2014, Ertz 20270 K (holotype: BR 5030171997880; isotype: TAN). Etymology. The epithet refers to the characteristic crown of white hairs near the perithecial apex. Diagnosis. This species differs from Porina trichothelioides R. Sant. in the septation of its ascospores (3–5 - septate in P. trichocoronata vs. 7 - septates in P. trichothelioides); in having slightly shorter and narrower ascospores (19–31 × 3.2–5 µm in P. trichocoronata vs. 28–32 × 4–5 µm in P. trichothelioides); in the overall much thicker perithecial walls which tend to be thicker in the lower part rather than the upper part; in its photobiont morphotype (rectangular and forming distinct radiate plates in P. trichocoronata vs. more or less angular in almost continuous plates in P. trichothelioides). Description. Thallus epiphyllous; dispersed to continuous with uneven margins, ca. 7 mm wide, and ca. 10–15 µm thick; slightly rugose, matt; green to yellowish green. Photobiont rectangular, arranged in radiate plates; ca. (9 –) 10–13 (– 14) × (2 –) 3–4 µm (n = 20). Perithecia superficial, well delimited from thallus, globose, constricted at base; smooth, matt; ca. 0.1–0.2 mm diam. (n = 13), and ca. 180 µm high; covered up to base with ca. 5–10 µm algiferous thallus layer; greyish black to black; crown of ca. 30 white hairs surrounding apex of perithecium, hairs thick and soft, consisting of agglutinated hyphae, sometimes fused into seta-like structures, ca. 30–100 µm in length and ca. 10–30 µm in width; ostiole inconspicuous, apex rounded, glabrous around ostiole. Crystallostratum not present. Excipulum and Involucrellum indistinguishable from one another, ca. 20–35 µm thick around the apex and ca. 40–50 µm thick at the remaining lower part; greyish blue to black, K -. Hamathecium hyaline; not inspersed; composed of thin, simple paraphyses ca. 1–2 μm diam., and ca. 80–100 µm long. Asci obclavate; 52–80 × 10–16 µm (n = 10); 8 - spored; with apical ring structure. Ascospores 3–5 - septate, broadly oblong to fusiform, often tapered on one or both sides, (19 –) 23–27.5 (– 31) × (3.2 –) 3.6–4.3 (– 5) µm, ratio L / B (4.2 –) 5.7–7.2 (– 8.3) (n = 101). Pycnidia not observed. Chemistry not tested for thallus; TLC not performed. Distribution and ecology. The species is known from only one locality in northern Madagascar. It inhabits the upper surface of leaves in mixed open woodlands at moderate elevation (ca. 1100 m). Notes. Porina trichocoronata most closely resembles the unsequenced P. trichothelioides, originally described by Santesson (1952). Both species share similarly coloured and shaped perithecia bearing a crown of white hairs, although the hairs appear somewhat longer in P. trichocoronata. Hair width was not reported for P. trichothelioides. The main differences concern the anatomy of the perithecial walls and the ascospores. In both species, the excipulum and involucrellum are not differentiated, but P. trichothelioides possesses a thicker black upper half (14–24 µm) and a thinner hyaline to light brown lower half (8–10 µm), whereas P. trichocoronata has uniformly greyish-blue to black perithecial walls that are thinner around the apex (20–35 µm) and thicker walls in the remaining lower part (40–50 µm) (Fig. 13 C). Furthermore, P. trichocoronata has 3–5 - septate ascospores that are slightly narrower and shorter than the 7 - septate ascospores reported for P. trichothelioides. The photobiont morphotype of P. trichothelioides cannot be determined with certainty. However, Santesson (1952) described the photobiont as “ more or less angular ” and arranged in “ almost continuous plates ”, which most likely corresponds to the angular-rounded, irregularly arranged morphotype recognised in the present study. This differs from the rectangular cells arranged in distinct radiate plates observed in P. trichocoronata (Fig. 13 D). The new species also resembles P. perminuta Vain. in having globose black perithecia bearing hairs (Santesson 1952). However, P. perminuta differs in having narrower perithecia with shorter greyish hairs, thinner perithecial walls throughout, and shorter 3 - septate ascospores. Although no rbc L sequence was recovered for P. trichocoronata, the photobiont morphology resembles that of algal clades 33 or 29 (Fig. 6 C – F). In the ITS phylogeny, P. trichocoronata was recovered within the Trichothelium clade (Fig. 3), whereas no mtSSU sequence was obtained. Some perithecia bear partially fused hyphal hairs forming seta-like structures. However, these structures remain soft and only sporadically developed, and are therefore interpreted as agglutinated hyphal hairs rather than true setae as in Trichothelium alboatrum Vain. (Santesson 1952). Pending a broader revision of the Trichothelium clade, the species is consequently assigned to the genus Porina. The combination of a distinct phylogenetic position and diagnostic differences supports the recognition of P. trichocoronata as a distinct species.