Trichothelium epiphyllum Mull. Arg.

Trichothelium cf. epiphyllum Müll. Arg., Bot. Jahrb. Syst. 6: 418. 1885. Fig. 19 A – C Type. CUBA • Unknown locality, Wright (holotype: G). Notes. Trichothelium epiphyllum has traditionally been regarded as a pantropical species, and specimens attributable to the current concept have previously been reported from Madagascar (Lücking 2008; Aptroot 2016). The present taxon is represented by seven specimens collected from northern and southern Madagascar (20271 F, 20272 I, 20279 F, 20279 J, 20279 K, 25340 B, and 25409 B). These specimens broadly agree with the description of T. epiphyllum reported by Lücking (2008), although they exhibit some morphological variation. Ascospores are 7 - septate and measure (28 –) 32.5–42 (– 50) × (3.7 –) 4.7–6.3 (– 7.3) µm (n = 125), broadly corresponding to the reported range of 35–45 × 4–5 µm. Both ascospore length and, particularly, width vary among specimens, with some producing distinctly broader spores. Perithecial morphology is likewise variable, especially in the form of the setae, which range from brush-shaped to lanceolate or acute, accurately matching the reported description. Perithecia are subglobose, black, and ca. 0.15–0.25 mm (n = 19) in diameter, while the setae measure ca. 0.2–0.4 mm (n = 32) in length. Altogether, these characters correspond closely to the published morphology of T. epiphyllum with perithecial ranges of 0.15–0.3 mm and 0.3–0.5 mm for setae. Phylogenetically, however, none of the mtSSU sequences cluster with the Neotropical T. epiphyllum lineage (Fig. 2). Instead, they are recovered in two distinct, well-supported subclades within the Trichothelium clade. This demonstrates that morphologically similar material occurs in multiple phylogenetic lineages and highlights the poor correspondence between phenotype and phylogeny within the clade. In the absence of sequences from type material, it remains impossible to determine whether the examined lineage represents T. epiphyllum s. str. or an undescribed species. Moderate genetic divergence is present within the Paleotropical lineage in both the mtSSU and ITS datasets, but no corresponding phenotypic differences could be identified. The taxon exhibited high photobiont selectivity and was exclusively associated with algal haplotype 33: 1 (Figs 4, 5). Overall, pending type-linked sequences, these specimens are therefore retained as T. cf. epiphyllum. Specimens examined. MADAGASCAR – Diego Suarez Prov. • Antsiranana, Region: Diana, District: Diego II, Commune: Joffreville, Forontany: Morafeu, National Park of Montagne d’Ambre, along trail from Gîte des Roussettes, across stream at small dam to dirt road, moist but not wet lower montane forest, with tall trees and tree ferns, 12°31'55"S, 49°10'33"E, alt. 1119 m, 7 Oct. 2014; Ertz 20271 F (BR, TAN). • ibid., across stream at small dam to dirt road and trail down to Lake Mahasarika, moist but not wet lower montane forest, with tall trees and tree ferns, 12°32'03"S, 49°10'28"E, alt. 1177 m, 7 Oct. 2014; Ertz 20272 I (BR, TAN). • ibid., West of Sambava, Marojejy National Park, along trail from Camp Simpona down to Camp Marojejia, rather dense humid montane forest, 14°26'20"S, 49°45'08"E, alt. ca. 1200 m, 23 Oct. 2014; Ertz 20279 F, 20279 J, 20279 K (BR, TAN). – Toliara Prov. • ca. 25 km Northwest of Fort-Dauphin (Tolagnaro), National Park of Andohahela, South part of parcel 1, ca. 5 km West of the village of Malio, 24°55'58"S, 46°44'07"E (ca. 200 m), 600–730 m, humid forest on the slopes of an inselberg, 29 Nov. 2019; Ertz 25340 B (BR, TAN). • ibid., South part of parcel 1, ca. 6.5 km West of the village of Malio, 24°56'24.1"S, 46°43'26.2"E, alt. 1000 m, dense humid forest, 01 Dec. 2019; Ertz 25409 B (BR, TAN).