Coenogonium subborinquense J. Kalb & K. Kalb, 2016

Kalb, Jutarat, Boonpragob, Kansri & Kalb, Klaus, 2016, New Coenogonium species (Ostropales: Coenogoniaceae) from Thailand, new reports and a revised key to the species occurring in the country, Phytotaxa 283 (2), pp. 101-122 : 118-119

Coenogonium subborinquense J. Kalb & K. Kalb , sp. nov. ( Figs. 5G , 8D )

Mycobank MB 818609

Similar to Coenogonium borinquense Mercado-Díaz & Lücking , but differs in having larger apothecia (0.2–0.4 mm in C. borinquense ) and a thick, cracked thallus (thin and continuous in C. borinquense ) without a prothallus (white-grey and glossy in C. borinquense ).

Type:— THAILAND. Rayong Province: Muang District; Pagoda Klang Nam near Pak Nam, in an old but polluted mangrove forest with dominant Rhizophora apiculata and Avicennia marina , ± 5 m. 12°40’06’’ N, 101°14’27’’ E, 27 February 2011, K. Kalb 38820 (RAMK, holotype).

Etymology:—The name refers to the similarity with C. borinquense , described recently from the Caribbean island of Puerto Rico (Mercado-Díaz et al., 2013).

Thallus crustose, corticolous, thick, cracked, grey or olive-grey, dull, partly glossy, 3–7 cm diam., with cartilaginous paraplectenchymatous corticiform layer, 10–20 μm thick; prothallus absent. Photobiont Trentepohlia , cells angular to rounded, in irregular plates or groups or short threads, 6–10 × 8–8 μm. Apothecia sessile, rounded, 0.3–0.8 mm diam., 180–250 μm high; disc plane, pale orange-yellow; margin distinct, not prominent except in young apothecia, smooth or rough to minutely denticulate, cream-colored to pale orange-yellow in old apothecia. Excipulum paraplectenchymatous with peripherally radiating cell rows, 20–30 μm broad, colorless, outer part I+ yellow-brown, inner part I–; cells isodiametric or elongate, thin-walled, 4–10 × 3–6 μm. Hypothecium 10–25 μm, colorless. Hymenium 80–100 μm, colorless, I+ blue then sordid blue-green then brown. Asci 70–90 × 9–11 μm. Ascospores oblique uniseriate, narrowly ellipsoid to fusiform with rounded ends, 1-septate, 10–14 × 2.5–3.5 μm, 4.0–4.7 times long as broad. Pycnidia pale orange-yellow, 0.1–0.3 mm, in irregular clumps ( Fig. 5G ); conidia bacilliform to broadly ellipsoid, 3–5 × 2–3 μm. Chemistry: no substances detected by TLC.

Distribution and habitat:—This rare lichen occurs in a very old polluted mangrove forest in the Gulf of Thailand. At present it is only known from the type locality where it is common.

Remarks:—As in C. borinquense , the size of the ascospores is intermediate between the smaller- and largerspored species. However, in contrast to C. borinquense this new species has much larger apothecia (0.2–0.4 mm diam. in C. borinquense ) and a thick, cracked thallus without a prothallus (thallus thin and continuous with a white-grey, glossy prothallus in C. borinquense ). Furthermore, the hymenium in C. subborinquense is higher and the asci are bigger with uniseriate ascospores which are biseriately arranged in C. borinquense . The following species have ascospores of similar length as in C. subborinquense : C. tavaresianum (Vězda) Lücking, Aptroot & Sipman , C. labyrinthicum Lücking & Kalb and C. aciculatum Lücking & Aptroot (Lücking & Kalb 2001; Rivas Plata et al. 2006; Vězda 1969). C. tavaresianum is known from Portugal and has a rugose-verruculose thallus and brownish orange apothecia; both C. labyrinthicum and C. aciculatum have larger, bright yellow apothecia (including the margin) and much narrower ascospores (1.5–2 μm broad).

Material from Thailand examined:—see type.

Coenogonium subluteum (Rehm) Kalb & Lücking, In : Lücking & Kalb, Bot. Jahrb. Syst. 122 (1): 34 (2000).( Figs. 5H , 8E )

Biatorina sublutea Rehm, Philip. J. Sci. Bot. 8: 404 (1913).

Thallus crustose, foliicolous, rarely muscicolous, continuous, thin, smooth, green, greenish grey or brownish grey, dull. Photobiont Trentepohlia , cells angular to rounded, mostly in irregular plates, partly short threads, cells 9–15 × 5–8 μm. Apothecia sessile, rounded, 0.2–0.5 mm diam., 70–100 μm high; disc plane or concave, pale wax-colored to pale orange; margin comparatively thick, prominent, smooth, of same color as disc. Excipulum 35–45 μm broad, colorless, outer part I+ light brown, inner part I–; cells isodiametric to elongate, ± thick-walled, 4–6 × 2–4 μm. Hypothecium 8– 14 μm high, colorless. Hymenium 60–70 μm high, colorless, I+ blue then quickly reddish brown then greyish brown. Asci 55–65 × 7–9 μm. Ascospores oblique-uniseriate or irregularly biseriate, ellipsoid, 1-septate, 6–12 × 3–3.8 μm, 2.1–3 times as long as broad. Pycnidia common, wart-shaped, 0.1–0.15 mm diam., pale green. Conidia bacillar, 1- septate, 12–18 × 2–3 μm. Chemistry: no substances detected by TLC.

Distribution and habitat:—Pantropical. This is by far the most common foliicolous species in the genus. In Thailand, it was collected in the understory of tropical rain forests, secondary forests, lower montane forests, dry evergreen forests, hill evergreen forests and mixed deciduous forests from 140–1395 m, thus showing a very wide ecological amplitude.

Remarks:—A similar species with a pantropical distribution is C. zonatum (Müll. Arg.) Kalb & Lücking , but it differs in having a thallus with a white prothallus and pycnidia are very rare.

Selected material from Thailand examined:— Nakhon Ratchasima Province: Khao Yai National Park, along trail from visitor center to Gibbon’s camp, epiphyllous in a tropical rainforest, 875 m, 14°26’26.19’’ N, 101°21’57.80’’ E, 20 June 2000, K. Papong RU-20477- 5 ( RAMK 009164 ) ; ibid., secondary forests, ca. 200 m behind Nhong Khing , 830 m, 14°25’7.29’’N, 101°22’18.52’’ E, 15 January 1999, K. Papong RU-16420 ( RAMK 004685 ) ; ibid., Pakchong district ; Khao Yai National Park, lower montane forests along main road 3077 at km 2 to Khao Khiao site, 830 m., 14°23’46.61’’ N, 101°22’45.63’’ E, 24 April 2000, K. Papong RU-19060 ( RAMK 009122 ) ; Saraburi Province: Kangkhoe district ; Khao Yai National Park, in dry evergreen forests along waterfall trail from Cha Om (check point 15) to Khlong Tam Tao , 140 m, 14°23’16.8’’ N, 101°10’26.7’’ E, 3 May 2000, K. Papong RU-19208-2 ( RAMK 009129 ) ; Nakhon Ratchasima Province: Khao Yai National Park, on moss in a hill evergreen forests SE of main road 3077 between the park headquarter and Khao Khieo , 1393 m, 14°21’39.90’’ N, 101°23’35.19’’ E, 2 September 2005, P. Nirongbut RU-22616 ( RAMK 008414 ) ; ibid., Pakchong district ; hill evergreen forests E of main road 3077 to Khao Khiao , 1375 m, 14°21’36.46’’ N, 101°23’46.83’’ E, 12 March 2000, K. Papong RU-18397, RU-18315-4 ( RAMK 009113 , RAMK 009099 ) ; ibid., trail at km-stone 9 of Khao Rom site, near junction to Khao Khiao , 800 m, 14°19’29.31’’ N, 101°34’39.91’’ E, 04April 1999, K. Papong RU-14035 ( RAMK 009042 ) ; Prachinburi Province: Nadi district ; Khao Yai National Park, near the station Bu Phram Nai ( Check Point 6), epiphyllous in a mixed deciduous forests, 185 m, 14°15’56.46’’ N, 101°51’09.33’’ E, 11 March 2000, K. Papong RU-17511, RU-17521 ( RAMK 004698 , RAMK 004699 ) .

Figures

FIGURE 5. A. Coenogonium convexum (KK 41133), transverse section through the crustose thallus showing the corticiform layer, scale 15 μm. B. Thallodiscs laying upside down on the thallus of Coenogonium isidiiferum (KK 41459), scale 0.3 mm, scale of inlet 0.1 mm. C. Coenogonium luteum (Schumm 8577), exciple coloured with lactophenol-anilinblue, scale 20 μm. D. Coenogonium leprieurii (RAMK 027804 b), ascus tip stained permanently blue with Lugol‘s solution. E. and F. Coenogonium aff. borinquense (KK 38577) showing different arrangement of ascospores within the asci of the same section, scales 5 μm and 10 μm. G. Coenogonium subborinquense (KK 38820), irregular shaped pycnidia, scale 0.2 mm. H. Coenogonium subluteum (RAMK 004684 b), hymenium stained with Lugol‘s solution; after some time, the upper part still remains blue while the lower part has turned red brown. I. Coenogonium luteum (Schumm 8577), hymenium stained with Lugol‘s solution; after some time, the whole hymenium has turned red brown. J. Conogonium barbatum (RAMK 004687), habitus, filamentous thallus projecting from the margin of a leaf, scale 1.5 mm.

FIGURE 8. Habitus photographs of Coenogonium species. A. Coenogonium nepalense (KK 35180), scale 1 mm. B. Coenogonium pineti (KK 38905), scale 0.3 mm. C. Coenogonium queenslandicum (KK 41131), scale 0.5 mm. D. Coenogonium subborinquense (KK 38820) thallus with apothecia and pycnidia (arrow), scale 1 mm. E. Coenogonium subluteum (KK 39803), scale 0.5 mm. F. Coenogonium verrucimarginatum (KJ 41288), scale 0.25 mm.