Solenopsora rhizomorpha A. Christy, Sequiera & S. Joseph

Christy, Arun, Sequeira, Stephen, Anilkumar, Aswathi & Joseph, Siljo, 2024, Solenopsora rhizomorpha (Catillariaceae): A new lichen species from India, Phytotaxa 652 (3), pp. 241-245 : 242-244

Solenopsora rhizomorpha A. Christy, Sequiera & S. Joseph , sp. nov. Mycobank No.: MB854033

( Fig. 2 )

Similar to Solenopsora elixiana Verdon & Rambold but differing in having an irregular or rosette-forming chalky white thallus with slightly larger subsessile to shortly stipitate apothecia, and lacking secondary metabolites.

Type:— INDIA. Kerala: Idukki district, Munnar , Eravikulam National Park , 10.1599° N 77.0709° E, elev. 2029 m, 22 November 2023, Arun Christy 23-40170 (holotype KFRI!, isotype MCH!)

Thallus saxicolous, small foliose, in irregular patches or rosette-forming, 1–1.5 cm wide. Lobes ca. 1–3 (–4) mm broad, 400–700 µm thick in section, corticate on both sides; upper surface chalky white, smooth, continuous, slightly convex, covered by white pruina, isidia and soredia absent; lower surface dark brown to black, attached by sparse pale to black rhizines; upper cortex filled with dull gelatinous substances, clearing in K, 40–65 µm thick; algal layer appears in irregular bundles, 100–160 µm thick; medulla of interwoven hyphae, 200–480 µm thick; lower cortex hyaline to brown, 80–140 µm thick. Photobiont chlorococcoid, cells spherical, 4.5–8.5 µm diam.

Apothecia lecanorine, ca. 0.5–1.7 mm diam., subsessile to shortly stipitate; disc plane to slightly convex, dark brown to blackish, usually slightly white pruinose when young; margin concolorous with the thallus, densely white pruinose when young, thalline excipulum eventually excluded at maturity. Epithecium pale brown. Hymenium hyaline, non inspersed, 50–70 µm high, K−, I+ dark blue; paraphyses sparingly branched, conglutinated, apices swollen, brown pigmented. Hypothecium hyaline, 70–140 µm high. Asci 8-spored, Catillaria - type, cylindrical-clavate, 33–45 × 9–13 µm, with KI+ evenly blue tholus, ocular chamber not seen.Ascospores hyaline, 1-septate, ellipsoid-elongate to slightly fusiform, 12–15 × 3–4 µm, without perispore.

Pycnidia not seen.

Chemistry: Cortex and Medulla K−, C−, KC−, P−, UV−. No chemicals detected by TLC.

Additional materials examined (paratypes): INDIA. Kerala: Idukki district, Munnar, Eravikulam National Park , 10.1599° N 77.0709° E, elev. 2029 m, 02 October 2020, Arun Christy 4237 (MCH) ; ibid., Mathikettan Shola National Park , 10.006° N 77.245° E, elev. 1740 m, 30 December 2021, Aswathi Anilkumar 5380 ( MCH) .

Etymology: The specific epithet ‘ rhizomorpha ’ refers to the presence of rhizines which is a characteristic feature in the new species.

Distribution and ecology: The species is found growing on open rocks in grasslands of Eravikulam National Park and Mathikettan Shola National Park. The species is restricted in its distribution and has only been found at these two locations so far. The specimens were collected from high-elevation areas (above 1700 m) that receive intense sunlight. In Eravikulam National Park, the specimens were found on open rocks near a stream and a waterfall, while in Mathikettan Shola National Park, they were found on open rocks near grasslands.

Notes: The new species, S. rhizomorpha is easily distinguished from most other known species of the genus by the presence of rhizines. Only the following species of Solenopsora were known to be rhizinate: Solenopsora elixiana Verdon & Rambold (1998: 401) , Solenopsora holophaea (Mont.) Sampaio (1921: 26) , Solenopsora marina (Zahlbr.) Zahlbruckner (1928: 756) . Although, the species mentioned above have rhizines, they differ from S. rhizomorpha in several taxonomically important characteristics. Table 1 provides a detailed comparison of these differences. Morphologically, S. rhizomorpha shows similarities with Solenopsora candicans (Dicks.) Steiner (1915: 288) by the presence of rosette forming, lobed marginate thallus. However, S. rhizomorpha can easily be distinguish from S. candicans with the presence of rhizines and the absence of secondary metabolites. S. candicans contains pannarin and zeorin which give the medulla a P+ orange reaction ( Dobson 2018, Guttová & Nimis 2021, Cannon et al. 2022, Nimis 2024).

Figures

FIGURE 2. Solenopsora rhizomorpha: A. Photograph of collection locality (holotype). B & C. Habits; D. An enlarged view of thallus. E & F. Cross section of thallus (E in K, F in water). G. Thallus section showing the algal layer (in water). H. Section of an apothecium (in K followed by LPCB). I. Section of hymenial region (in LPCB), inset: ascospores (in KI). Scale bars: B & C = 5 mm; D, E & H = 500 µm; F = 100 µm; G & I = 50 µm.