Introduction
Renowned for its exceptional diversity in humid and tropical rainforests and being one of the dominant lichenized genera, Porina Acharius (Acharius Reference Acharius1809: 158) continues to gain significant attention, now remarkably comprising c. 400 accepted species (McCarthy Reference McCarthy2013). This number, however, will undoubtedly increase, with hundreds of potentially undescribed species expected to be discovered, especially in the understudied regions of Asia. Nested within the family Porinaceae, the genus is set apart amongst pyrenocarpous lineages due to its distinctive unitunicate asci. Porina is considered the most speciose genus among foliicolous lichenized fungi and exhibits notable substratum specificity, with nearly half of the taxa colonizing only bark and one-third living on leaves (Santesson Reference Santesson1952; Lücking Reference Lücking2008). The Porina epiphylla subgroup, in particular, is exclusively foliicolous. It is characterized by its association with a Phycopeltis photobiont and by narrower ascospores (3–6 μm, and 7–14 times as long as wide), compared to other species in the Porina group. These generally produce broader spores, except for a small number with truly filiform ascospores (Lücking & Vězda Reference Lücking and Vězda1998). This group typically inhabits the shaded understorey of humid tropical lowland forest.
Porina species exhibit diverse perithecioid ascomata, varying from lens-shaped and hemispherical to subglobose and wart-shaped to even conical perithecia, occasionally with a tomentose covering. In addition, ascospores exhibit diversity in their shape, ranging from bacillar, oblong to fusiform, and are typically transversely septate, rarely muriform. Species of Porina share many anatomical features with the genus Trichothelium in Trichoteliaceae but are distinguished by the distinctively setose perithecia. Furthermore, certain Porina species growing on leaves and with black perithecia, may superficially resemble members of the genus Strigula. However, the latter is distinctly differentiated by its bitunicate asci, containing 1-septate ascospores (Lücking Reference Lücking1992, Reference Lücking2004; Lücking & Caceres Reference Lücking and Cáceres1999).
Mt Kitanglad Range Natural Park (MKRNP), a protected area in the southern Philippines, is renowned for its exceptional biodiversity and endemism (Amoroso et al. Reference Amoroso, Laraga and Calzada2011). Its unique microhabitats and altitudinal gradients provide an ideal environment for the growth and diversification of lichens, including foliicolous species. Field surveys carried out around the foot of Mt Kitanglad, specifically the Cinchona Forest Reserve Station in Barangay Kaatuan, Lanpatan, Bukidnon, have uncovered a species previously unknown to science. The discovery of the new lichen species highlights the importance of continued exploration, documentation and conservation efforts within the Philippine archipelago.
Material and Methods
External morphology was studied and measured using a stereoscope and a compound microscope. Hand-cut sections and squash preparations of ascomata and thalli were mounted and examined in water, in a 10% potassium hydroxide solution (K), and in Lugol's iodine solution (I) with or without K pretreatment. For measurement and illustration purposes, thin hand-cut sections of the specimens were mounted in water only. In the descriptions, dimensions of perithecia, involucrellum, ascospores and asci are presented as mean values with extreme values in parentheses. Total numbers of measurements made are given in square brackets [n]. Voucher specimens were dried and deposited in the Philippine National Museum (PNH) and the Central Mindanao University Herbarium (CMUH).
Taxonomy
Porina dolichoepiphylla Taer, Dal Forno & Aptroot sp. nov.
MycoBank No.: MB 856120
Similar to Porina virescens (Kremp.) Müll. Arg. in having a continuous, nitidous thallus and no visible prothallus; its phycobiont being a Phycopeltis species with angular-rounded irregular cells, with perithecia that are lens-shaped when young to hemispherical when mature, c. (0.3–)0.5–0.7 mm diam.; and in its 7–septate, bacillar-shaped ascospores, 54–71 μm long. However, the new species differs by the absence of hairs in the thalli and perithecia (vs the presence of hairs, covering both the thalli and perithecia in P. virescens), and by having a rough thallus with undeveloped primordia of perithecia (vs a smooth to minutely uneven thallus in P. virescens).
Type: Philippines, Mindanao Island, Province of Bukidnon, Municipality of Lantapan, Barangay Kaatuan, Mt Kitanglad Range Natural Park, Cinchona Forest Reserve Station, 1298 m elevation, on frond of Asplenium vittaeforme in shady forest, 22 September 2022, E. C. Taer ECT 291 (PNH!—holotype; CMUH!—isotype).
Figure 1. Porina dolichoepiphylla (holotype). A, habit of thallus and ascomata. B, section of perithecium showing involucrellum. C, section of thallus showing Phycopeltis photobiont with angular-rounded cells and irregular plates. D, asci. E, ascospores. Line drawings by Julieferd Torres. Scales: A = 0.5 mm; B & C = 200 μm; D & E = 20 μm.
Figure 2. Porina dolichoepiphylla (herbarium holotype). Scale = 1 mm. In colour online.
Thallus continuous, medium-sized, rough with undeveloped primordia of perithecia, nitid, greenish grey (fresh) or yellowish grey (herbarium), marginally dispersed with no visible prothallus; isidia and soralia absent. Phycobiont a species of Phycopeltis with angular-rounded cells and irregular plates.
Perithecia solitary, dispersed, lens-shaped (young) to almost hemispherical (mature), 0.31–0.52 mm diam., yellowish brown (fresh) or pale cream (herbarium); ostiole apical, minute papillate, in shallow depression. Involucrellum c. 15–22 μm, conspicuous, dimidiate, covering half of the exciple, brownish. Excipulum c. 15 μm thick, pale yellowish brown. Asci obclavate, I−, c. (81–)86–119 × 15–19 μm [n = 20], 8-spored. Ascospores 7-septate, bacillar (ends acute and proximal ends slightly tapering), I−, c. 54–71 × 3–6 μm [n = 27].
Chemistry
Thallus K−; asci I−, KI−.
Etymology
The specific epithet dolichoepiphylla refers to the relatively longer ascospore size, a characteristic shared with one other species in the P. epiphylla subgroup. However, P. dolichoepiphylla can be distinguished from the morphologically similar species P. virescens by its hairless surface and rough thalli.
Distribution and habitat
The species is so far known only from the type locality in Mt Kitanglad, specifically in the shady lower montane forest of the Cinchona Forest Reserve Station, Barangay Kaatuan, Lantapan, Bukidnon, where it grows on a frond of Asplenium vittaeforme. Associated species also collected within the locality are Porina applanata Vain., P. atriceps (Vain.) Vain., P. epiphylla (Fée) Fée, P. limbulata (Kremp.) Vain. and P. rufula (Kremp.) Vain.
The type locality is situated at the foot of Mt Kitanglad Range Natural Park (MKRNP), known as one of the few Cinchona plantations left in the Asia-Pacific, and also hosting an established 2 ha permanent plot for Long Term Ecological Research (LTER). Mt Kitanglad Range Natural Park is a well-known protected sanctuary in Central Mindanao, Philippines, and is one of the ASEAN Heritage Parks. The park reaches 2899 m in elevation, harbouring a wide range of ecosystems from tropical lowland forests to mossy forests near the summits.
Notes
Further morphological studies based on the literature confirmed that the new species has conspicuously longer ascospores, distinct from all other species of the Porina epiphylla subgroup: P. albicera (Kremp.) Overeem (13–25 μm long); P. andreana Lücking & Vězda (10–15 μm long); P. atriceps (27–35 μm long); P. atropunctata Lücking & Vězda (20–35 μm long); P. conica R. Sant. ((27–)34–48 μm long); P. epiphylla s. str. (26–32 μm long); P. lucida var. australiensis Lücking & Vězda (30–38 μm long); P. lucida var. lucida R. Sant. ((30–)35–48 μm long); P. mirabilis Lücking & Vězda ((35–)40–45 μm long); P. similis Kalb & Vězda (32–45 μm long); P. subepiphylla Lücking & Vězda (30–43 μm long). The exception is P. virescens, but the new species differs by its hairless surface and rough thalli. In addition, P. dolichoepiphylla shares thallus and ascospore characteristics with P. kadavuensis Farkas, a species recently described from the Fiji Islands (Farkas Reference Farkas2023). However, P. kadavuensis is distinguished by its smaller, narrower ascospores measuring 23–28(–35) μm in length, with irregular 3–5(–7) septations.
The Porina epiphylla subgroup is exclusively foliicolous, characterized by its association with a Phycopeltis photobiont and by the comparatively narrow ascospores lacking a gelatinous sheath, with most species confined to the shaded understorey of humid tropical lowland forest (Lücking & Vězda Reference Lücking and Vězda1998).
Checklist of Philippine Porina species
The most recent lichen funga checklist from the Philippines (Paguirigan et al. Reference Paguirigan, Dela Cruz, Santiago, Gerlach and Aptroot2020) reveals a rich diversity of Porina, comprising 39 accepted species (including two varieties), with 20 species (51%) described originally from Philippine specimens. The high proportion of species with Philippine-type localities emphasizes the country's significance in Porina taxonomy.
In the current contribution, we report 12 additional taxa, three of which were overlooked in the previous checklist, seven are known only from unpublished herbarium data, and two are newly cited records published in the literature (including the new species described here). Furthermore, synonymization with species already present in the country are included: P. mirabilis under P. alba (R. Sant.) Lücking; P. arengae Vain., P. blumeana Vain. and P. sapotae Vain. under P. corruscans (Rehm) R. Sant.; P. insperata Müll. Arg. under P. epiphylla; P. flocculosa Vain. under P. virescens; and P. multiseptata (Müll. Arg.) Lücking and P. pandanorum Vain. under P. virescens f. multiseptata (Müll. Arg.) Lücking. Our updated checklist (Table 1) now comprises 51 Porina taxa, with 44 accepted species (including one form).
Table 1. Updated checklist of Porina species reported in the Philippines (n = 51) and their locality within the archipelago. Taxa in bold denote type collections from the Philippines. * = References based on unpublished herbarium records located on the Lichen Portal.
Across the major island groups, 82% of Porina taxa have been recorded from Luzon, 19% from Mindanao, while only 10% occurred in the Visayas. The records are most concentrated in the northern part of the country, which is attributed to historical factors influencing collection efforts within the island.
Evaluating the spatial data suggests that some areas, particularly in Mindanao and smaller islands, seem to be under-represented. The apparent distributional pattern highlights the need for more extensive sampling efforts across the archipelago to obtain a more accurate view of Porina distribution and diversity.
Foliicolous species of the Porina epiphylla subgroup known from the Philippines
1 Thallus and perithecia tomentose ……… 2
Thallus and perithecia glabrous ……… 3
2(1) Ascospores regularly 7-septate, 45–75 μm long ……… P. virescens
Ascospores irregularly 7–15-septate ……… P. virescens f. multiseptata
3(1) Ascospores 3–5-septate, 10–30 μm long ……… 4
Ascospores 7(–9)-septate, 20–70 μm long ……… 5
4(3) Ascospores 3–5-septate, 10–25 μm long; thallus smooth; perithecia lens-shaped to hemispherical, base not spreading, well delimited from surrounding thallus; ascospores 3-septate, 13–25 μm long ……… P. albicera
Ascospores 3–5 (–7)-septate, 23–28 (–35) μm long; thallus distinctly warted ……… P. kadavuensis
Reported from the Fiji Islands (Farkas Reference Farkas2023); probably present in the Philippines.
5(3) Perithecia with broadly spreading base, not well delimited from surrounding thallus, central part flat or slightly prominent; ascospores bacillar, 10–15 times as long as wide; disc-shaped isidia of Phyllophiale alba-type often present; thallus yellowish; perithecia with central part not differing from periphery ……… P. alba [syn. Porina mirabilis]
Perithecia lens-shaped to wart-shaped or conical, well delimited from surrounding thallus; ascospores oblong to fusiform, 6–10 times as long as wide ……… 6
6(5) Perithecia distinctly conical with vertically projecting top ……… P. conica
Perithecia lens-shaped to wart-shaped, if conical then top not projecting but with blackish point around ostiole ……… 7
7(6) Perithecia 0.4–0.6 mm; ascospores narrowly oblong (35–48 × 4–5.5 μm), 8–10 times as long as wide; old perithecia often with a darker spot around ostiole; pycnidia rare ……… P. lucida
Perithecia 0.2–0.45 mm ……… 8
8(7) Perithecia with blackish spot around ostiole; ascospores narrowly fusiform to oblong (3–4.5 μm wide), 7–10 times as long as wide; thallus often dispersed into rounded patches ……… P. atriceps
Perithecia without dark spot; thallus usually continuous ……… 9
9(8) Perithecia 0.3–0.5 mm; ascospores 54–71 × 3–6 μm ……… P. dolichoepiphylla
Perithecia smaller; ascospores smaller ……… 10
10(9) Perithecia 0.2–0.3 mm; ascospores 20–25 × 2–3 μm ……… P. minutissima
Perithecia 0.25–0.45 mm; ascospores 26–32 × 3–4 μm ……… P. epiphylla
Acknowledgements
The authors would like to express their profound gratitude to the United States National Science Foundation (NSF) for funding the collaborative projects NSF-DEB 1754697 and 1754667. ECT would also like to acknowledge the Department of Science and Technology (DOST) under the ‘Science and Technology Regional Alliance of Universities for National Development’ scholarship programme. In addition, we would like to extend our gratitude to the Protected Area Management Board (PAMB) of Mt Kitanglad Range Natural Park, Center for Biodiversity Research and Extension in Mindanao (CEBREM) and Central Mindanao University, through our University President, Dr Rolito G. Eballe for the tremendous help and logistical support.
Author ORCIDs
Ermalene C. Taer, 0009-0000-1498-5232; André Aptroot, 0000-0001-7949-2594; Victor B. Amoroso, 0000-0001-8865-5551; Alma B. Mohagan, 0000-0002-8303-5131, Fulgent P. Coritico, 0000-0003-3876-6610; and Manuela Dal Forno, 0000-0003-1838-1676.
Competing Interests
The authors declare none.
