Enterographa ducouretiana Lebreton & Ertz, 2023

Lebreton, Elise, Carriconde, Fabian, Brouste, Damien, Lespagnol, Antoine, Stenger, Pierrelouis, Sérusiaux, Emmanuël & Ertz, Damien, 2023, Enterographa ducouretiana sp. nov. (lichenized Ascomycota, Roccellaceae), a new foliicolous species from New Caledonia, Phytotaxa 609 (3), pp. 247-252 : 248-249

Enterographa ducouretiana Lebreton & Ertz , sp. nov. MycoBank No.: MB849332

( Figs. 1 & 2 )

Foliicolous Enterographa with lirelliform ascomata immersed in pseudostromata, a dark purple hypothecium, (3–)5-septate ascospores measuring (16–)20.5(–24) × (2.5–)2.9(–3.5) µm and PD+ yellow pseudostromata.

Type:— NEW CALEDONIA. Province Sud, Col de Mouirange, in rainforest patch surrounded by shrubland vegetation, called ‘maquis’, 22°12’9.216” S, 166°40’11.244” E, November 18, 2022, Lebreton 1787a (holotype: PC0779840 ; isotypes: LG11991-ETR00A , NOU, BR) .

Thallus continuous, smooth, thin, c. 15–30 µm thick, pale yellowish green, sometimes with a whitish tinge, matt, esorediate. Photobiont trentepohlioid; cells elongated and irregular in outline, 7–11 × 3.5–9 µm, in irregular plates.

Ascomata immersed in pseudostromata covered by the thallus, distinctly elongate-lirellate, usually sparsely branched; disc dark brown to black in young and older ascomata (with a purplish tinge when fresh), slit-like, 0.12–0.9 mm long and 0.02–0.04 mm broad, epruinose; pseudostromata solitary, prominent, with ± gentle flanks not constricted at base, 0.23–1 × 0.18–0.35 mm, smooth, pale yellowish green with an orange tinge (more strongly pronounced in fresh material), or white where the thallus is abraded; in section white and incrusted with hyaline, tiny crystals that dissolve in K. Exciple indistinct, c. 3–5 µm wide, I-, KI-. Subhymenium very thin, c. 5 µm high, colorless, I-, KI-. Hypothecium 12–17 µm tall, dark purple, K+ becoming black. Hymenium 55–65 µm tall, colorless, clear, I+ orange-red, KI+ persistently dark blue; epihymenium poorly defined, hyaline, I+ orange-red, K-. Paraphysoids branchedanastomosing, c. 1 µm thick, slightly enlarged at their apex, c. 1.5 µm thick. Asci narrowly clavate, 54–59 × 12–13 µm (n = 3), KI- except for a KI+ blue, ring-shaped structure surrounding a tiny ocular chamber. Ascospores hyaline, narrowly fusiform, (3–)5-septate, (16–)20.5(–24) × (2.5–)2.9(–3.5) µm, with a 1.5–2 µm thick gelatinous sheath.

Pycnidia not observed.

Chemistry: thallus: K-, C-, PD-, UV-, but pseudostromata PD+ yellow (probably due to the presence of psoromic acid); thin-layer chromatography not performed.

Etymology: This new species is named after Emilie Ducouret due to her essential role in coordinating the fieldwork in New Caledonia that led to its discovery.

Distribution and habitat: Enterographa ducouretiana is known only from the type collection in rainforest near a creek.

Notes: The new species fits well in the genus Enterographa because of its trentepohlioid photobiont, ascomata with an inconspicuous exciple, branched paraphysoids, clavate asci with a KI+ blue ring structure in the tholus, and hyaline, narrowly fusiform, septate ascospores. The new species is unique within the genus by the presence of a dark purple hypothecium. It is also characterized by the continuous thallus with narrowly lirelliform ascomata that are immersed in PD+ yellow pseudostromata covered by the thallus, a dark brown to black hymenial disc, and (3–)5-septate ascospores. Enterographa membranacea P.M. McCarthy & Elix (2018:49) resembles E. ducouretiana in having simple to sparsely branched lirelliform ascomata that are immersed in PD+ yellow pseudostromata covered by a thallus layer and (5–)6- septate ascospores of 18–25 × 2–3 µm. It differs from E. ducouretiana in having larger pseudostromata (0.4–1.5(–2) × 0.4–0.8(–1) mm) with plate-like crystals of calcium oxalate. The hymenial disc are pale to medium brown and the hymenia are taller (65–85 µm). Unlike E. ducouretiana , it lacks a dark purple hypothecium and instead has a hyaline to pale yellowish-brown hypothecium, K- and 15–22(–25) µm thick. Enterographa membranacea also differs in having a corticolous habit, even though growing on the smooth trunk of a palm tree, a substrate with a texture similar to leaves. The photobiont cells are much broader (7–10 µm), solitary or in very short filaments and not arranged in plates ( McCarthy & Elix 2018). Among the foliicolous species of Enterographa with a PD+ yellow thallus and somewhat similar ascospores, E. bartlettii Sérus. (1984:292) differs from the new species in having a thallus dispersed in patches, much shorter ascomata (0.15–0.3 mm) with a pale orange brown disc, a thalline margin densely filled with calcium oxalate crystals, an algiferous layer next to the excipulum and (6–)7-septate ascospores that are broader (3.5–5 µm); E. bella R. Sant. (1952:106) has a photobiont with cells arranged in radiating plates, a thallus dispersed in patches, a deep orange-brown hymenial disc and 7-septate ascospores that are longer (22–29 µm); E. foliicola Lücking & Matzer (1996:111) has a photobiont with cells arranged in radiating plates, ascomata slightly constricted below with oxalate crystals in the thalline margin and 7(–9)-septate ascospores that are broader (3.5–5 µm); E. multiseptata R. Sant. (1952:108) , E. perez-higaredae Herrera-Campos & Lücking (2002:213) and E. vezdae Sparrius (2004:63) have longer ascospores with notably more septa (7, 7–10(–14), 7–9 septate, respectively; Sparrius 2004, Lücking 2008). All these species also differ from the new species by the absence of a dark purple hypothecium. Among the corticolous and saxicolous species of Enterographa , E. elixii Sparrius (2004:39) is somewhat similar to the new species in having ascomata immersed in well-defined pseudostromata and in having dark hymenial discs, but this lichen has notably rounded to short lirelliform ascomata, a thick thallus (100–300 µm) and 3-septate ascospores ( Sparrius 2004).

Figures

FIGURE 1. Enterographa ducouretiana sp. nov. A–B. Fresh specimen, photographed on collection day. C–D. Herbarium specimen (holotype), three months after collection. Scales: A-D = 0.5 mm. Photos A and B by Damien Brouste; C and D by Damien Ertz.

FIGURE 2. Enterographa ducouretiana sp. nov. (three months old herbarium specimen). A, B & E. Cross-sections of ascomata showing the purple tinge of the hypothecium and the thallus layer covering the surface of the pseudostromata (in water). C. Cross-section of an ascoma in K (note the color of the hypothecium that became black and the dissolution of the crystals in the margin that became more transparent). F. Thallus with trentepohlioid photobiont in irregular plates (in water). D. Ascus with spores (in water). G. Ascospores (in water). Scales: A–C, E–F = 20 μm, D & G = 5 μm. Photos by Damien Ertz & Elise Lebreton.