Cryptothecia aleurodes (Nyl.) Makhija & Patw., 1985

Borgato, Luca & Ertz, Damien, 2020, Cryptothecia aleurodes (Arthoniaceae), a misunderstood species, Phytotaxa 449 (1), pp. 90-94 : 91-93

Cryptothecia aleurodes (Nyl.) Makhija & Patw. ( Fig. 1 )

≡— Arthothelium aleurodes (Nyl.) Zahlbr., Cat. Lich Univers. 2: 120 (1922).

Basionym:— Arthonia aleurodes Nyl., Bull. Soc. Linn. Normandie , sér.2, v.3: 273 (1869).

Type: — GUADELOUPE, [Houelmont], 500-600 m elev., on bark, 1868, Husnot (H-NYL 5717— lectotype! selected by Makhija & Patwardhan 1985).

Thallus corticolous, crustose, epiphloedal, whitish-grey, smooth to rough, ecorticate, c. 40–80 µm thick, with calcium oxalate crystals; prothallus not seen. Photobiont trentepohlioid. Vegetative propagules absent. Ascigerous areas conspicuous, white, irregular, not raised above the thallus level, branched and very elongated, 0.1–0.5 mm wide.

Asci globose, 100–110 μm. Paraphysoids branched-anastomosing, c. 1–2 μm wide. Ascospores hyaline, I–, KI–, oblong to ellipsoid, densely muriform, 8/ascus, 12–15 × 5–7-septate, (36–)43–71 × (18–)24–34 µm (n=29); lumina ±rectangular or triangular; gelatinous sheath present (c. 1–2 µm wide).

Secondary Chemistry: —Thallus and ascomata C+ red, K–, Pd–, UV+ white. TLC (solvents A, B, C, EA and G): Gyrophoric (major) and lecanoric (trace; only in specimen ERTZ 18461) acids, an unknown substance UV+ sky blue after heating (Rf: 68 in A, 34 in B, 80 in G; major), an unknown substance UV+ greyish-white after heating (Rf: 48 in B; minor) and an unknown terpenoid (Rf: 70 in B; trace). Type specimen and specimens ERTZ 18461 and 18528 tested.

Distribution and ecology: —Littoral forest on sand, on trunk. Known from the Caribbean.

Remarks: —To our surprise, the study of the lectotype of C. aleurodes revealed a K– and C+ red thallus containing notably gyrophoric acid as major substance and lacking norstictic acid, as in the specimens from Martinique. This is in contradiction to the determination keys of Makhija & Patwardhan (1985, 1994) and Jagadeesh-Ram & Sinha (2016). Makhija & Patwardhan (1985) also analysed the lectotype but their annotation does not specify the C reaction. Jagadeesh-Ram & Sinha (2016) did not analyse it, but instead an Indian specimen from the Nicobar Islands (Jagadeesh-Ram 3270A, 30.05.2014, PBL) that probably represents a different species.

The revision of the three specimens of C. aleurodes published from the Seychelles Islands ( Seaward & Aptroot 2009) and from Thailand ( Wolseley & Aptroot 2009) revealed different species. These three specimens differ from C. aleurodes in having slightly elevated, rounded-to irregular ascigerous areas. The two specimens from the Seychelles Islands (Norkett 16166, 17018) have also larger ascospores (76–89 × 38–49 µm) and TLC revealed the absence of norstictic acid and the presence of an unknown very pale bluish-grey substance (Rf = 40 in solvent A) at the same level of norstictic acid and two unknown terpenoids (Rf = 62 and 68 in solvent A). The specimens from the Seychelles could not be identified using the world-wide key of Jagadeesh-Ram & Sinha (2016). The specimen from Thailand (Aguirre -Hudson & Wolseley 3398) has minute dark brown to blackish dots visible on its ascigerous areas, a P+ yellow thallus and our TLC analysis revealed psoromic acid. Wolseley & Aptroot (2009) have published this specimen as C. aleurodes (Fig 4, page 414, and page 416), stating that the species contains norstictic acid, which is not present in our TLC extracts. In addition, the data of the specimen on page 416 of the publication are partly incorrect (see below for the correct data). We identified the specimen from Thailand as Cryptothecia farinosa Jagadeesh, G.P. Sinha & Kr. P. Singh (2009: 608) , a species known from India. This species is very close to Cryptothecia verrucominuta Makhija & Patw. (1994: 70) , a species already reported from Thailand, which also contains psoromic acid. C. farinosa differs from the latter only by the slightly larger ascospores and the presence of an algal layer (heteromerous thallus; Jagadeesh-Ram et al. 2009).

Due to the contradictory information in the literature, we provide a description of Cryptothecia aleurodes based on the lectotype from Guadeloupe and on very similar specimens from Martinique (see above). This lichen might be restricted to the Neotropics, and perhaps even to the Caribbean islands, because the revision of specimens recently reported from the Seychelles Islands and Thailand revealed very different species. Specimens of C. aleurodes were also reported from India ( Jagadeesh-Ram & Sinha 2016) and were not revised in the framework of the present study. Because these specimens from India ( Jagadeesh-Ram & Sinha 2016) were described as having a C– thallus and as containing norstictic acid, they obviously do not belong to C. aleurodes and should be revised.

Additional specimens of C. aleurodes examined: — MARTINIQUE. North of Le Prêcheur , north part of L’Anse du Céron, 14° 50’ 05” N, 61° 13’ 22” W, alt. 25 m, littoral forest, on smooth bark, 28 September 2013, D. Ertz 18461 (BR) ; Le Diamant , Grande Anse du Diamant, 14° 28’ 35’’ N ; 61° 02’ 10’’ W, alt. 15 m, Littoral forest on sand, with big trees, 30 September 2013, D. Ertz 18528 (BR) .

Examined specimens misidentified as C. aleurodes : — SEYCHELLES ISLANDS. Mahé, Sans Souci Road , alt. 100 m, 22 August 1973, A. H. Norkett 16166 (BM) ; Mahé, Top of Brilliant River Gorge , alt. c. 330 m, on one small tree, 4 October 1973, A. H. Norkett 17018 (BM) . THAILAND. Uthai Thani, Khao Nang Rum , alt. 460 m, dry evergreen forest, 12 January 1992, B. Aguirre - Hudson & P. A. Wolseley 3398 (BM) .

Figures

FIGURE 1. Cryptothecia aleurodes (A, D–E: H-NYL5717-lectotype; B–C, F–G: Ertz 18461). A–C Thallus with elongated white ascigerous areas. D Ascus with ascospores in KOH. E Ascospores in KOH. F–G Ascospores in water. Scale bars: a=2 mm, b–c=1 mm, d–e=20 µm, f–g=10 µm (Photos A–E: D. Ertz; F–G: L. Borgato).