Introduction
The lichen genus Enterographa Fée (Roccellaceae) has been expertly monographed by Sparrius (Reference Sparrius2004) and is characterized by the following characters: crustose growth habit, photobiont Trentepohlia or Phycopeltis, rounded to elongate or punctiform ascomata, most usually immersed in the thallus, exciple poorly developed, hamathecium of branched and anastomosing paraphysoids, ellipsoid to cylindrical-clavate asci of the Opegrapha-type, ascospores usually fusiform with thin septa and perispore, without enlarged terminal cells, conidiomata punctiform, and bacilliform or filiform microconidia. As circumscribed, the genus comprises 35 species, while the related genus Sclerophyton Eschw. includes species with macrocephalic ascospores with relatively thick septa and ascomata included in pseudostromata, with well-known and widespread species such as Enterographa elegans (Eschw.) Tuck, and E. extenuatum (Nyl.) Redinger being transferred to Sclerophyton. Since the monograph by Sparrius (Reference Sparrius2004), 8 further new species have been described in the genus Enterographa and one species transferred into it (Ertz et al. Reference Ertz, Christnach, Wedin and Diederich2005; Sparrius et al. Reference Sparrius, Saipunkaew, Wolseley and Aptroot2006; Aptroot et al. Reference Aptroot, Saipunkaew, Sipman, Sparrius and Wolseley2007; Cáceres Reference Cáceres2007; Sparrius & Aptroot Reference Sparrius and Aptroot2007; Sparrius & Björk Reference Sparrius and Björk2008; Jagadeesh Ram et al. Reference Jagadeesh Ram, Sinha and Singh2008).
In spite of several detailed studies (Grube Reference Grube1998; Myllys et al. Reference Myllys, Lohtander, Källersjö and Tehler1999; Tehler Reference Tehler1990; Tehler et al. Reference Tehler, Lohtander, Myllys, Sundin, Tibell and Hedberg1997) generic delimitation within the Roccellaceae is unsatisfactory and several genera are most probably polyphyletic or paraphyletic (D. Ertz, pers. comm.). A detailed phylogenetic study of two genes by Tehler & Irestedt (Reference Tehler and Irestedt2007) could even demonstrate parallel evolution of the fruticose growth form in the supposedly well-circumscribed genera Roccella and Roccellina. The recent inclusion of Chiodecton epiphyllum Sérus., a species growing over a foliicolous species of Coenogonium in Papua New Guinea and the Neotropics, in Enterographa as a “better solution” than its earlier assignment to Plectocarpon Fée, shows that more data should be gathered to reach a well-supported delimitation of the genus (Ertz et al. Reference Ertz, Christnach, Wedin and Diederich2005).
Santesson (Reference Santesson1952) recognized three foliicolous species of Enterographa. Since then Vězda (Reference Vězda1975), Sérusiaux (Reference Sérusiaux1984), Lücking (Reference Lücking1991), Sérusiaux (in Aptroot et al. Reference Aptroot, Diederich, Sérusiaux and Sipman1995), Lücking & Matzer (Reference Lücking and Matzer1996), Matzer (Reference Matzer1996), Lücking et al. (Reference Lücking, Sérusiaux, Maia and Pereira1998), Herrera-Campos & Lücking (Reference Herrera-Campos and Lücking2002), Lücking et al. (Reference Lücking, Wirth, Ferraro and Cáceres2003), Lücking & Henssen (in Sparrius Reference Sparrius2004) and Sparrius & Björk (Reference Sparrius and Björk2008) described further new species. A total of 15 foliicolous species of Enterographa are currently known, including 2 lichenicolous fungi on foliicolous lichens (Sparrius Reference Sparrius2004; Ertz et al. Reference Ertz, Christnach, Wedin and Diederich2005); most of them distributed in the Neotropics and eastern Palaeotropics. Only two species (E. multiseptata and E. vezdai) have so far been recorded from the African continent.
Here we describe two further foliicolous species belonging to Enterographa, discovered by the first author in Kakamega Forest (W Kenya) in August 2006. One was clearly overgrowing the thallus of a species of Coenogonium and the second most probably had the same ecology.
Materials and Methods
Morphological characters were studied on dry specimens under a dissecting microscope. Anatomical characters were measured using light and interference contrast microscopy on hand-cut sections and squash preparations mounted in water. Water solution of KOH (10%) and lactophenol-cotton blue were used for detailed observation of asci and hamathecial elements. Amyloidy of the tholus of asci and hymenium were tested with Lugol's solution.
The study site
Kakamega Forest is located in Shinyalu Division of the Kakamega District in the Western Province of Kenya. It is situated about 40 km north-west of Lake Victoria between 0°10′ and 0°21′ N latitude and 34°47′ and 34°58′ E longitude and is made up of a main forest block covering 8500 ha surrounded by five forest fragments of various sizes (130–1400 ha; Farwig et al. Reference Farwig, Böhning-Gaese and Bleher2006). The vegetation consists of a mosaic of primary rainforest, secondary forests at different stages of development, swamp and riverine forest, selectively logged forest, plantations of indigenous and exotic tree species, natural glades, and clearings resulting from anthropogenic disturbance (Tattersfield et al. Reference Tattersfield, Seddon and Lange2001; Althof Reference Althof2005). Kakamega Forest is the easternmost patch of the equatorial forests distributed over the Congo basin and the only tropical rainforest with a mixture of Guineo-Congolian and afromontane species in Kenya (Althof Reference Althof2005).
The Species
Enterographa fellhaneroides Yeshitela, Eb. Fisch., Killmann & Sérus. sp. nov
Differt ab omnibus speciebus foliicolis generis Enterographa ascomata apothecioideis vel breve lirelliformibus, disco fusco cum margine albido et ascosporibus 6-septatis fusiformibus apicibusque rotundatis. Enterographa brezhonega differt ab E. fellhaneroides ascomata longe lirelliformibus saepe ramificatis et disco atrofusco. Enterographa seawardii differt sporibus 7–11-septatis anguste fusiformibus et thallo cum Pd+ luteo.
Typus: Kenya, Western Province, Kakamega Forest, 00°21′.276″ N and 034°51′.519″ E, 1609 m, on living leaves of Dracaena fragrans, 14 August 2006, Yeshitela 349 (LG—holotypus).
(Figs 1 & 2)
Enterographa fellhaneroides (holotype). A–C, habit of apothecia; D, section through the apothecium. Scales: A–C = 0·2 mm; D = 50 μm.
Enterographa fellhaneroides, ascospores. Scale = 3 μm.
Thallus absent, ascomata overgrowing the thallus of a non-filamentous Coenogonium which is continuous, smooth, greyish green, usually with a whitish prothallus, photobiont Trentepohlia with cells angular-rounded, 12–20 × 5–8 μm.
Ascomata sessile, ±aggregated, rounded to shortly lirelliform, constricted at base, 0·2–0·8 mm diam., rarely up to 0·6 mm long, 50–60 μm high; disc exposed, pale to dark brown; margin 40–50 μm thick, slightly raised, whitish. Excipulum 10–15 μm wide, formed by densely interwoven hyphae filled with large crystals, hyaline or pale straw in section. Hypothecium 120–155 μm high including a 100–130 μm socle (formed by densely intricate hyphae filled with large, angular and hyaline oxalate crystals), hyaline, K–. Hymenium 50–75 μm high, light brown in the upper part (c. 25 μm), otherwise hyaline, I+ blue, rapidly turning red, KI+ blue. Epithecium 5–8 μm high, orange-brown; K–. Hamathecium of branched and anastomosing paraphysoids, c. 1·5 μm thick, not swollen apically. Asci of the Opegrapha-type, ellipsoid to clavate, bitunicate, 30–35 × 7·5–10 μm, with apical KI+ blue ring. Ascospores 4–6 per ascus, fusiform, with rounded ends, 6-septate, not constricted at the septa, the median cell usually slightly enlarged,hyaline, 15–18 × 2·5–3 μm, perispore up to 0·5 μm thick.
Conidiomata not found.
Chemistry. No compounds detected by TLC.
Etymology. When we first observed the apothecia of this species, we considered it to be a poorly developed specimen of Fellhanera Vězda until the anatomical features pointed to Enterographa. Hence, the specific epithet is chosen to indicate this resemblance.
Notes. Enterographa fellhaneroides is easily distinguished from other foliicolous species assigned to the genus by its apothecioid or short lirelliform ascomata, with a pale brown disc and a whitish margin, and 6-septate, fusiform ascospores with rounded ends. Its closest related species appears to be the recently described E. brezhonega (Sparrius & Aptroot Reference Sparrius and Aptroot2007), overgrowing the thallus of epiphytic Porina rosei in W France, and reported from the New Forest (S England) on the same host (Hitch Reference Hitch2008). This species is distinguished by its lirelliform, often branched ascomata with a dark brown to black disc. Otherwise both species are very similar, especially the ascospores.
Morphologically, Enterographa fellhaneroides looks similar to E. seawardii Lücking & Henssen, a recently described foliicolous species (in Sparrius Reference Sparrius2004) and only known from the Seychelles, because of similar prominent, open, angular-rounded to shortly lirellate ascomata with pale orange discs. However, Enterographa seawardii is easily distinguished by its 7–11-septate, narrowly fusiform ascospores, 30–40 × 3–4 μm and its Pd+ yellow (probably psoromic acid) thallus.
Ecology and distribution. Enterographa fellhaneroides is so far known only from Kakamega Forest in Western Kenya in near primary and middle-aged secondary forest fragments. It is a lichenicolous species overgrowing thalli assigned to a Coenogonium sp. (poorly developed but typical apothecia seen). The species is a component of the foliicolous lichen flora of the understorey.
Selected specimens examined. Kenya: Western Province: Kakamega Forest, Kisere fragment 00°22′.966″ N, 034°53′.751″ E, 1594 m, on living leaves of Chrysophyllum albidum, 2006, Yeshitela 373 (KOBL); Kisere fragment, 00°23′.151″ N, 034°53′.595″ E, 1580 m, on living leaves of Teclea nobilis, Dracaena fragrans and Cassipourea ruwenzorensis, 2006, Yeshitela 538, 539 & 537 (KOBL); Isecheno fragment, 00°14′.522″ N, 034°51′.959″ E, 1580 m, on living leaves of Cassipourea ruwenzorensis, 2006, Yeshitela 484 & 493 (KOBL).
Enterographa meklitiae Yeshitela, Eb. Fisch., Killmann & Sérus. sp. nov
Differt ab omnibus speciebus foliicolis generis Enterographa ascomata numerosis punctiformibus in pseudostromata immersis. Enterographa epiphylla differt ab E. meklitiae pseudostromata convexibus punctiformibus ad vix lirellatis vel irregularibus, ascomata nigricantibus et ascosporibus majoribus 6-septatis.
Typus: Kenya, Western Province, Kisere fragment of Kakamega Forest, 00°23′.151″ N and 034°53′.595″ E, 1612 m, on living leaves of Dracaena fragrans, 24 August 2006, Yeshitela 539 (LG—holotypus).
Enterographa meklitiae (holotype). A–C, habit of apothecia; D, section through the apothecium. Scales: A & B = 0·2 mm; C = 100 μm; D = 50 μm.
Enterographa meklitiae, ascospores. Scale = 3 μm.
(Figs 3 & 4)
Thallus assumed to be absent, ascomata most probably overgrowing the thallus of a non-filamentous Coenogonium which is continuous, smooth, greyish green, photobiont Trentepohlia with cells angular-rounded, 12–20 × 3–7 μm.
Ascomata punctiform, 0·05–0·1 mm diam., arranged in groups of 8–12(−20) in pseudostromata, visible as punctiform (30–50 μm diam.) brownish spots. Pseudostromata rounded or irregular in outline, imarginate, convex to ± plane, 0·2–0·5 mm diam., up to 75 μm high, surface greyish green to whitish, not constricted at base, in section encrusted with large, angular and hyaline Ca oxalate crystals, K–. Excipulum very thin, c. 5 μm wide, pale straw. Hypothecium 10–15 μm high, pale straw, K–, I+ blue rapidly turning red, KI+ blue. Hymenium hyaline, I+ blue rapidly turning red, KI+ blue, 50–60 μm high. Hamathecium of branched and anastomosing paraphysoids, c. 1·5 μm thick, not swollen apically. Epithecium indistinct. Asci of the Opegrapha-type, ellipsoid to clavate, bitunicate, 37–50 × 7–10 μm, with apical KI+ blue ring. Ascospores 4 per ascus, 4–5-septate, ellipsoid to fusiform, with rounded ends, the median cell sometimes slightly enlarged, (13–)15–17 × 2·5–3 μm, not constricted at the septa, perispore < 5 μm thick.
Conidiomata not observed. Conidia sometimes produced from tissue inside ascomata (probably the excipulum), simple, c. 2·5 × 1 μm, bacilliform, hyaline.
Chemistry. No compounds detected by TLC.
Etymology. This species is dedicated to Meklit, the daughter of the first author.
Notes. Enterographa meklitiae can easily be distinguished from other foliicolous species of Enterographa by its numerous, punctiform ascomata immersed in pseudostromata. At first glance, it looks like the conidiomata of the Neotropical Phyllobathelium leguminosae (Cavalc. & A. A. Silva) Lücking & Sérus. (see fig. 7E in Lücking et al. Reference Lücking, Sérusiaux, Maia and Pereira1998). It is close to Enterographa epiphylla (Sérus.) Ertz et al., which overgrows the foliicolous lichen Coenogonium flavicans, and which can be distinguished by its convex pseudostromata, punctiform to slightly lirellate, or irregular, and blackish ascomata, and its larger ascospores (17–22 × 3–4·5 μm) with consistently 6 septa.
Ecology and distribution. Enterographa meklitiae is so far recorded only from Kakamega Forest in Western Kenya. The type locality is a near-primary rain forest dominated by Strychnos usambarensis, Uvariopsis congensis, Pouteria altissima (=Aninngeria altissima), Cassipourea ruwensorensis, Dracaena fragrans, Funtumia africana, Diospyros abyssinica, and Heinsenia dieverilleoides. There is no strong evidence that it is a lichenicolous species overgrowing the thallus of a non-filamentous Coenogonium, but it is assumed to have such an ecology. Indeed, its ‘thallus’ is very similar to that of Enterographa fellhaneroides (in one collection, both species grow over the same thallus), and all genuinely lichenized foliicolous species of Enterographa have Phycopeltis as photobiont (Sparrius Reference Sparrius2004).
Selected specimens examined. Kenya: Western Province: Kakamega Forest, Isccheno, 00°14′.522″ N, 034°51′.959″ E, 1580 m, on living leaves of Cassipourea ruwensorensis, 2006, Yeshitela 484 (KOBL).
Discussion
As with most other genera in the Roccellaceae, the delimitation of the genus Enterographa requires further studies, hopefully based on molecular sequences from several genes. Nevertheless, the four species described or discussed in this paper (Enterographa epiphylla, E. brezhonega, E. fellhaneroides and E. meklitiae) characterized by their lichenicolous habit on thalli with Trentepohlia as photobiont and 4(–6) fusiform ascospores with rounded ends per ascus, an even number of septa and the median cell slightly enlarged, seem to be closely related. It is premature to suggest the taxonomic recognition of that group but equally, its inclusion in Enterographa, Plectocarpon or Sclerophyton is not fully satisfactory.
We wish to thank very warmly Dr. Damien Ertz from the National Botanical Garden of Belgium for important comments and suggestions; we further thank both anonymous referees for their interesting suggestions. The study was funded by the German Ministry of Education and Research (BMBF) within the BIOTA East project E04 (LC0625C1). The first author was funded by the German Catholic Academic Exchange Service (KAAD). Thanks are also due to the Kenya Wildlife Service (KWS) in Nairobi for a research permit in Kakamega Forest. We would also like to thank the staff of the East African Herbarium (EA) at the National Museums of Kenya (NMK), Nairobi and the Kenyan Wildlife Service field office in Kakamega for logistic support.
