Striatiguttula nypae S.N.Zhang, K.D.Hyde & J.K.Liu, sp. nov.

Zhang, Sheng-Nan, D. Hyde, Kevin, Gareth Jones, E. B., Jeewon, Rajesh, Cheewangkoon, Ratchadawan & Liu, Jian-Kui, 2019, Striatiguttulaceae, a new pleosporalean family to accommodate Longicorpus and Striatiguttula gen. nov. from palms, MycoKeys 49, pp. 99-129 : 108-109

Striatiguttula nypae S.N.Zhang, K.D.Hyde & J.K.Liu, sp. nov. Figure 3

Etymology.

The epithet reflects the genus name of the host plant Nypa fruticans , from which the specimens were collected.

Type.

THAILAND. Ranong: Ranong, on decayed rachis of Nypa fruticans Wurmb ( Arecaceae ), 3 December 2016, S.N.Zhang, SNT44 (holotype: MFLU 18-1576; isotype: HKAS 97480; ex-type living culture MFLUCC 18-0265 = GZCC 18-0005).

Description.

Saprobic on mangrove palm Nypa fruticans . Sexual morph: Stromata in vertical section 240-380 µm high, 195-385 µm diameter, (x̄ = 318.2 × 289.0 µm, n = 15), black, scattered, gregarious, immersed beneath host epidermis, and erumpent to superficial, with a papilla or short to long neck up to 550 µm, subglobose or conical, uni-loculate or bi-loculate, coriaceous to carbonaceous, ostiolate, periphysate, papillate and clypeate, glabrous or somewhat interwoven pale brown hyphae or with setae, lying at apex of the neck. Peridium 9-16 µm thin, composed of several pale brown to hyaline angular cells, compressed and pallid inwardly. Wall of the clypeus composed of brown cells of textura epidermoidea and dark brown host tissue. Wall of the neck with thicker and elongated angular cells. Hamathecium 1-2 µm wide, trabeculate pseudoparaphyses, septate, branched, filamentous, anastomosing, embedded in a gelatinous matrix. Asci 64-145 × 8-17 µm, (x̄= 106.3 × 13.8 µm, n = 30), 8-spored, bitunicate, fissitunicate, cylindric-clavate, pedicellate, apically rounded, with an ocular chamber. Ascospores 18-26 × 4-6 µm, (x̄ = 22.2 × 5.3 µm, n = 50), hyaline to brown, uniseriate to biseriate or triseriate, fusiform, 1-3-septate, constricted at the central septum, the upper middle cell slightly swollen towards the central septum, straight or slightly curved, striate, guttulate, end cells slightly paler, surrounded by a mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics.

Colonies on PDA attaining 15 mm diam. within 21 days at 25 °C under natural light, velvety, centrally raised, greenish grey or greyish olivaceous, reverse dull green or grey olivaceous, with a margin of translucent, milky white to hyaline mycelia.

Additional specimens examined.

Thailand. Krabi: near Pali, Mueang Krabi District, on submerged decaying rachis of Nypa fruticans Wurmb ( Arecaceae ), 30 August 2017, S.N.Zhang, SNT207 (paratype: MFLU 18-1577; living culture MFLUCC 17-2517 = GZCC 18-0006); Thailand. Krabi: near Pali, Mueang Krabi District, on submerged decaying rachis of Nypa fruticans Wurmb ( Arecaceae ), 30 August 2017, S.N.Zhang, SNT208 (paratype: MFLU 18-1578; living culture MFLUCC 17-2518 = GZCC 18-0007).

Habitat and distribution.

Inhabiting Thai mangrove forests, Andaman sea (west) coastline, Thailand.

Notes.

Striatiguttula nypae varies in ascomatal appearance, mostly immersed beneath the plant surface, sometimes visible as a papilla or dome-shaped area on the plant surface, and becomes erumpent to superficial, with a papilla or a short to long neck. The typical morphological characters of S. nypae are the appearance of stromata, with interwoven pale brown hyphae or setae at the apex of the neck, and the hyaline to brown, 1-3-septate, fusiform ascospores, striate, guttulate, with slightly paler end cells and a mucilaginous sheath. We have compared Striatiguttula nypae to previously encountered species on Nypa fruticans , and several morphologically similar mangrove fungal species. However, the striation of ascospores can be a reliable morphological character to distinguish Striatiguttula nypae from Astrosphaeriella nipicola ( Hyde and Fröhlich 1998), A. nypae ( Hyde 1992a) and Leptosphaeria spp. ( Spegazzini 1881, Cribb and Cribb 1955, Hyde et al. 1999, Pang et al. 2011), which are characterized by one or three septa and hyaline or brown ascospores. The presence of erumpent to superficial stromata, the number of septa and size of ascospores in S. nypae are also different from Trematosphaeria spp. (Table 3), despite being quite similar in ascospore morphology. In addition, the phylogenetic analysis showed that the three isolates of Striatiguttula nypae clustered together and were distinct from S. phoenicis .