Buellia vizagensis R. Ngangom & Nayaka, 2025

Ngangom, Roshinikumar, Nayaka, Sanjeeva, Mohabe, Satish & Reddy, A. Madhusudhana, 2025, New and interesting saxicolous species of Buellia De Not. (Caliciaceae, lichenized ascomycota) from India, Phytotaxa 681 (3), pp. 265-276 : 268-271

Buellia vizagensis R. Ngangom & Nayaka , sp. nov. MycoBank No.: MB856019

Type:— INDIA. Andhra Pradesh, Vishakhapatnam, Simhachalam area near Cashew plantation, on siliceous rock 06 March 1986, D.D. Awasthi, G. Awasthi, R. Mathur & P. Srivastava 86.256 (holotype LWG-LWU, isotype LWG).

( Fig. 3 )

Thallus saxicolous, crustose, epilithic, usually warm white to whitish grey, rimose to areolate, thin to moderately thickened up to 0.15 mm; prothallus visible as black margin only around thallus; medulla white, I+ blue, lacking calcium oxalate (H 2

SO 4

−).

Apothecia numerous, lecideine, initially adnate soon becoming sessile, round, single or in groups, 0.3–0.8 mm diam., margin thick and distinct, black or color masked by greyish necrotic layer; disc black, flat becoming convex at maturity, finely covered with yellowish brown pruina, which are more prominent in younger apothecia; exciple leptocline - type, 50–60 µm thick, dark brown, with aeruginose pigments (K−, HNO 3 + violet); epihymenium brown, 8–9 μm thick (K–, HNO ₃–); hymenium hyaline 50–60 µm high, not inspersed with oil droplets; paraphyses simple to moderately branched, apically swollen (3–4.5 µm diam.), with brown pigment cap (cf. elachista brown) and diffuse aeruginose pigment absent; hypothecium dark brown, 100–130 μm high; asci clavate, Bacidia- type, 8-spored. Ascospores 1-septate, brown at maturity, oblong to ellipsoid, usually not constricted at septum, Buellia - type, proper septum and spore wall thin, not thickening during spore ontogeny, ornamentation absent, (7–)8.2–11(–12) × (4–)4.3– 5.3(–6) µm, l/w= (1.5–)1.6–2.2(–2.6) (n = 30).

Pycnidia not observed.

Chemistry: Spot tests: K+ yellow turning red (forming crystals), P+ yellow, C−. Thallus UV + orange. TLC: norstictic acid (major), 4,5-dichlorolichexanthone (major), connorstictic acid (minor).

Etymology: The specific epithet “ vizagensis ” refers to the old name (Vizag) of the type locality.

Distribution: The new species is known only from the type locality in the hilly, coastal region of Southern India. It was growing on siliceous rock near a cashew plantation at elevations up to 300 m.

Notes: Buellia vizagensis is closely related to B. nilgiriensis S.R. Singh & D.D. Awasthi (1981:187) in having UV + orange thallus but distinguished from B. vizagensis by smaller (0.2–0.7 mm) immersed to adnate apothecia with epruinose disc, larger ascospores (9–16 × 5–7 µm) and lacking connorstictic acid. Morphologically, Buellia vizagensis shares similarities with B. halonia however, the later species is distinguished by occasionally having a bright red pigment (eumitrin) in the medulla. Further, Buellia halonia has a leptocline- type exciple that contains an aeruginose HNO ₃+ violet pigment which extends up to the epihymenium, whereas in B. vizagensis , the pigment is restricted to the outer exciple only. Additionally, B. halonia has larger ascospores (12.4–15.7 × 6.8–8.0 µm) ( Bungartz et al. 2007). Buellia mamillana (Tuck. 1868:226) W.A. Weber (1986:493) also has a rimose areolate, UV + orange thallus, but latter species can be distinguished by its distinctly different mamillana - type exciple (initially lecanorine, transitioning to lecideine), epruinose apothecia, larger ascospores (12–15 × 6–8 µm) and the presence of atranorin along with other xanthones ( Bungartz et al. 2007). Buellia lepidastra (Tuck. 1858:429) Tuck (1888:90) . is another species with aeruginose pigmentation usually confined to outermost exciple, but it differs in having granular to verrucose thallus, aethalea - type exciple and lacking xanthones ( Bungartz & Nash 2004a).

Figures

FIGURE 3. Buellia vizagensis (holotype LWG-LWU).A-B.Thallus and habitat,C. Section showing leptocline -type exciple after applying KOH and then cleaning crystal with distilled water, D. ascospores. Scale bars:A. 2 mm, B. 1 mm, C. 50 µm, D 15 µm.