Coenogonium verrucimarginatum 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 : 120

Coenogonium verrucimarginatum J. Kalb & K. Kalb , sp. nov. ( Fig. 8F )

Mycobank MB 818610

Similar to Coenogonium coronatum , but differs in having apothecia with a verrucose-denticulate margin (ciliate in C. coronatum ) and in growing on bark (epiphyllous in C. coronatum ).

Type:— THAILAND. Ratchaburi Province: Suan Phueng ditrict ; Tambon Suan Phueng, trail to Kao Chon Waterfall (Nine-Level Waterfall), bamboo scrub with scattered deciduous trees along a creek (mixed deciduous forest), 200–250 m. 13°31‘31.4‘‘ N, 99° 14‘23.7‘‘ E, 11 December 2015, J. Sutjaritturakan & K. Kalb 41283 ( RAMK, holotype) .

Etymology:—The name refers to the verrucose margins of the apothecia.

Thallus crustose, corticolous, continuous, thin, smooth, dull, yellowish green to vivid green, 5–40 mm diam., without a distinct corticiform layer; prothallus absent. Photobiont Trentepohlia , cells angular to rounded, mostly in irregular plates, partly short threads, cells 6–10 × 4–7 μm. Apothecia sessile, rounded in outline, 0.15–0.45 mm diam., 140–170 μm high; disc plane, slightly concave in young apothecia, pale wax colored to cream; margin thin, prominent, densely denticulate, cream-colored to whitish. Excipulum paraplectenchymatous with irregularly arranged cells, 20–40 μm broad, outer part I+ yellow-brown, inner part I–; cells globose to elongate, thin-walled, 3–10 × 2–7 μm. Hypothecium 15–30 μm high, colorless to pale yellowish. Hymenium 90–100 μm high, colorless, I+ blue then quickly sordid green then brown. Asci 60–70 × 7 (if spores oblique-uniseriate) –8 μm (if spores irregularly biseriate). Ascospores oblique-uniseriate or irregularly biseriate, broadly ellipsoid, 1-septate, 8–11 × 3.5–4.2 μm, 2.0–3.2 times as long as broad. Pycnidia not observed. Chemistry: no substances detected by TLC.

Distribution and habitat:— Thailand. At present known from several collections from the type locality where C. verrucimarginatum grows on bark of deciduous trees in a mixed deciduous forest between 200– 300 m.

Remarks:—The new species is very similar the C. coronatum described recently by Neuwirth et al. (2015). C. coronatum is distinguished from C. verrucimarginatum by having ciliate apothecial margins instead of denticulate margins and has only been found growing on leaves. C. subluteum is also similar, but the apothecial margin of this epiphyllous species is smooth and usually of the same color as the disc.

Material from Thailand examined:— Ratchaburi Province: Suan Phueng district ; Tambon Suan Phueng, trail to Kao Chon Waterfall (Nine-Level Waterfall), bamboo scrub with scattered deciduous trees along a creek (mixed deciduous forest), 200–300 m. 13°31‘31.4‘‘ N, 99° 14‘23.7‘‘ E, 11 December 2015, J. Sutjaritturakan & K. Kalb 41288, 41296 (herb. K. & J. Kalb) .

Figures

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.