Sculptolumina conradiae H. Mayrhofer, Giralt, van den Boom & Elix, 2014

Sculptolumina conradiae H. Mayrhofer, Giralt, van den Boom & Elix sp. nov.

( Fig. 4 View FIGURE 4 ) MycoBank MB 807086

Similar to Sculptolumina japonica (Tuck.) Marbach but differs in lacking secondary metabolites, by the presence of only a few hymenial oil droplets and in having 1–3-septate ascospores (19.0–)21.0–27.2(–29.0) × (8.0–)9.4–12.7(–15.0) µm with four 4 ±rounded lumina at maturity and smooth walls. Pycnidia and conidia unknown.

Type: ― GUATEMALA. (A) Quezaltenango: WSW of Quezaltenango, San Martín, SE of village, along path to Laguna Chicabal , mixed forest on NW slope, scattered outcrops along path and at open places, on trunk of mature Alnus arguta, 2700 m , 14º 48.2’ N, 91º38.8’W, 22 July 2004, P. & B. van den Boom 32863 (holotype GZU! GoogleMaps , isotype hb. v.d.Boom! GoogleMaps ).

Thallus indeterminate, discontinuous, composed of scattered to contiguous granules, bullate (ca. 0.05 mm diam.) to minutely squamulose and sublobate (ca. 0.2 mm diam.), pale to dark brown. Prothallus absent. Medulla not amyloid, I-. Photobiont trebouxioid; algal cells up to 10 µm diam. Apothecia lecideine, 0.2–0.4(–0.7) mm diam., adnate to sessile, black. Proper margin rather thick and prominent in young apothecia, becoming thinner, usually persistent, black. Disc concave to plane, rarely becoming subconvex, epruinose, black. Proper exciple, aethaleatype, 30(–50) µm wide, composed of rounded cells 5.0–7.0 µm diam., outer part dark brown, inner part hyaline. Epihymenium brown, N-. Hymenium hyaline, without or with a few oil droplets, 90–110 µm high. Hypothecium up to 70 µm deep, dark brownish-black, upper part black-olivaceous, N-, ±inspersed with oil droplets. Asci Bacidia - type, 8-spored but often with only 4–6 well-developed ascospores. Paraphyses with apical cells 3.0–4.0 µm wide, with brown caps. Ascospores 1–3-septate, (19.0–)21.0–27.2(–29.0) × (8.0–)9.4–12.7(–15.0) µm (M= 21.1 × 11.1 µm; SD = 3.1 × 1.7 µm; n= 23), ellipsoid, with four lumina, similar to the Conradia - type; septal or central lumina ±rhomboid to rounded, apical lumina ±hemispherical to rounded; lateral walls thick; torus absent or poorly developed at central septum; walls not ornamented. At first lumina only septal, later with two additional apical lumina connected to the septal lumina by a short to indistinct canal (isthmus) which may be interrupted or not (rarely) by the insertion of an additional septum. Ontogeny type-A (the septum is inserted before apical inner wall thickenings become distinct). Pycnidia and conidia not seen.

Chemistry: ―All spot tests negative; no lichen substances detected by TLC.

Etymology: ―The epithet refers to the similarity of its ascospores to the Conradia - type of Rinodina conradii Körb. It is the first known species in the genus Sculptolumina Marbach with 3-septate ascospores.

Ecology and distribution: ―This species is known from two localities, both situated at an elevation of 2700 m. All collections were from the trunks of Alnus arguta . In the mixed forest at the type locality, S. conradiae was very abundant on several rather small trees. Adjacent lichens included Chrysothrix xanthina (Vain.) Kalb , Flavoparmelia caperata (L.) Hale, Hypotrachyna rockii (Zahlbr.) Hale , Japewiella tavaresiana (H. Magn.) Printzen , Parmotrema sorediiferum Hale , Physcia alba (Fée) Müll. Arg. , P. poncinsii Hue , Punctelia perreticulata (Räsänen) G. Wilh. & Ladd , P. subrudecta (Nyl.) Krog and Thelenella modesta (Nyl.) Nyl. All of these species were recorded previously in van den Boom et al. (2007).

Notes: ― Sculptolumina conradiae is characterized by the brownish, granulose to minutely squamulose thallus which lacked secondary metabolites, the lecideine apothecia, ± 0.5 mm diam. with black, epruinose discs, the poorly developed, carbonaceous proper exciple, the hymenium lacking or including only a few oil droplets, the dark brown hypothecium, the Bacidia- type asci and the large, smooth walled, 1–3-septate ascospores with markedly thickened lateral and septal inner walls, resulting in 4 ±rounded lumina (similar to the Conradia- type). Despite the ascospores of S. conradiae are similar to those of R. conradii , the additional diagnostic characters of the new species clearly preclude its inclusion in the genus Rinodina (Ach.) Gray , characterized by lecanorine apothecia, colourless hypothecium and Lecanora- type asci.

The new species is far better included in the genus Sculptolumina for the following reasons: 1) the thalline and apothecial characters are consistent with those of Sculptolumina japonica ; 2) among the genera of Physciaceae segregated from Buellia s. lat. by Marbach (2000), only Sculptolumina has ascospores with very pronounced inner wall thickenings at all stages of ontogeny (rinodinoid-ascospores). The genus is also characterized by hymenia inspersed with oil droplets. Although the new species lacks or has only a few oil droplets in the hymenium, this character has proved to be variable in other genera of Physciaceae (e.g. Buellia s. str., Chrismofulvea Marbach , Cratiria Marbach , Endohyalina Marbach emend. Giralt, van den Boom & Elix , Rinodina and Stigmatochroma Marbach ). Filiform conidia are a further diagnostic feature of Sculptolumina ( Giralt et al. 2009) but, unfortunately, they have not been observed in S. conradiae .

Presently, the genus Sculptolumina includes only two taxa, the type species, S. japonica and S. serotina . They differ from S. conradiae in both their chemistry and ascospores. S. japonica contains anthraquinones and has Mischoblastia - type ascospores whereas S. serotina contains the lobaric acid chemosyndrome and has ascospores similar to those of S. conradiae but 1-septate, with only two rounded lumina (± Pachysporaria- type) instead of 3- septate, with four rounded lumina. Both grow on bark, lignum or decaying plants, mainly in subtropical to tropical regions and are also present in Guatemala.

The 3-septate ascospores of S. conradiae somewhat resemble the tetralocular but 1-septate ascospores of Orcularia placodiomorpha (Vain.) Kalb & Giralt and O. placodiomorphoides (Imshaug) Kalb & Giralt ( Kalb & Giralt 2011). However, the sequence for the differentiation of the lumina and the canals (isthmus) are clearly different. In the new species immature ascospores are 1-septate with two lumina divided by a septum and not connected by a canal (or isthmus). Later during the ontogeny, with spore maturation, each one of the two lumina differentiates an apical lumen; the apical and central lumina of each cell are connected by a short canal. Finally, a new septum is inserted in this short canal and the ascospores become 3-septate.

This ontogeny contrast with species of Orcularia (Malme) Kalb & Giralt , where at one stage of its spore ontogeny each ascospore cell has an apical lumen and both lumina are connected by a long canal. During the ontogeny, this canal differentiates by swelling a central lumen per cell. No septa are inserted between the apical and central lumina of each cell, thus the ascospores remain 1-septate. The immature, colourless, non-septate ascospores of Orcularia are also different and characteristic of this genus. They have one single lumen ± bone-shaped as the consequence of strong lateral inner wall thickenings which appear before the septum is inserted ( Kalb & Giralt 2011). This contrasts with Sculptolumina where the septum is formed early on.

The 3-septate ascospores of Rinodina conradii are also superficially similar but their development follows a type-B ontogeny (the septum is inserted after the apical thickenings become distinct). Consequently, simple, nonseptate ascospores and 1-septate ascospores always show apical thickenings (cf. Mayrhofer et al. 2001).

Finally, the Callispora - type ascospores with very strong subapical, inner wall thickenings (1-septate with four locules or 3-septate) of some species of Buellia s. str (= Hafellia Kalb, H. Mayrhofer & Scheid. in Kalb), e.g. B. fraudans (Starbäck) Elix , B. gomerana (Etayo & Marbach) Giralt & van den Boom , B. pseudotetrapla (Pusswald) Elix and B. tetrapla (Nyl.) Müll. Arg. (cf. Etayo & Marbach 2003) also resemble the ascospores of Sculptolumina conradiae .

Additional specimens examined: ― GUATEMALA. (A) Quezaltenango: WSW of Quezaltenango, San Martin, SE of village, along path to Laguna Chicabal , mixed forest on NW slope, scattered outcrops at open places, 2700 m, 14° 48.2' N, 91° 38.8' W, 22 July 2004, P.& B. van den Boom 32875 (paratype hb. v.d.Boom). GoogleMaps (A) S of Quezaltenango, S of Llano del Pinal, N slope of volcano Santa Maria , path among small agriculture fields with small forests, shrubs, trees and outcrops, 2700 m, 14° 46.6' N, 91° 33.3' W, 23 July 2004, P.& B. van den Boom 32980 (hb. v.d. Boom) GoogleMaps .