Rhexocercosporidium camporesii Phutthacharoen & K.D. Hyde, 2021

Phutthacharoen, Kunthida, Chethana, K. W. Thilini, Phookamsak, Rungtiwa, Mckenzie, Eric H. C. & Hyde, Kevin D., 2021, Rhexocercosporidium camporesii sp. nov. (Ploettnerulaceae, Helotiales) from Italy, Phytotaxa 482 (1), pp. 14-24 : 18

Rhexocercosporidium camporesii Phutthacharoen & K.D. Hyde , sp. nov. ( Fig. 1 )

Index Fungorum number:—IF 556989, Facesoffungi number:—FoF 06821

Etymology:—“ camporesii ” referring to Erio Camporesi, the collector of the fungus

Holotype:—MFLU 17-1594

Saprobic on dead stems. Sexual morph: Apothecia 400–600 × 250–450 µm (x̄ = 500 × 350 µm, n = 10), when dry, single or gregarious, scattered on wood, sessile, black, erumpent to immersed, rough surface. Receptacle concave. Disc flat, black, rough. Margin black. Ectal excipulum 30–85 µm (x̄ = 50 µm, n = 10) composed of 4–5 layers of thick-walled cells of textura angularis, outer layer light brown to black, inner layer hyaline. Medullary excipulum 30–50 µm (x̄ = 36 µm, n = 10) composed of hyaline cells of textura oblita. Hymenium hyaline, inner mixed with asci and paraphyses. Paraphyses 2–2.5 µm wide (x̄ = 2 µm, n = 20), numerous, long, filiform, branched, aseptate, hyaline, thin-walled. Asci 55–80 × 5–10 µm (x̄ = 62 × 8 µm, n = 20), 8-spored, unitunicate, cylindrical, hyaline, inoperculate, thin-walled, sessile to subsessile, with truncate base, apically conical, with slightly truncate at the end, with J+, apical ring. Ascospores 10–20 × 3–4 µm (x̄ = 15 × 3 µm, n = 20), overlapping 1–3-seriate, hyaline, ellipsoidal to fusiform, aseptate, smooth- and thin-walled, with small guttules. Asexual morph: Undetermined.

Material examined:— ITALY. Forlì-Cesena, Riofreddo, Bagno di Romagna, on dying aerial stem of Scabiosa maritima L. ( Caprifoliaceae ), 20 August 2017, E. Camporesi, IT 3447 (MFLU 17-1594, holotype).

GenBank numbers—ITS: MN688634 , LSU: MN688632 .

Notes:—In the phylogenetic analysis, Rhexocercosporidium camporesii is clustered sister to Pirottaea brevipila (CBS 309.58) with high support in BI analysis (0.99 BYPP), but low support in ML and MP analyses (50% ML, 34% MP). Unfortunately, the P. brevipila strain does not link to any type material or morphological description ( Vu et al. 2019). However, the illustrations of the holotype of P. brevipila shows black hair surrounding the apothecia and the species lacks an amyloid ring ( Schroeter 1889). In contrast, Rhexocercosporidium camporesii does not have hair around the apothecia, and it has an amyloid ring. Morphology of our new species differed significantly from the other Rhexocercosporidium species , and these differences are listed in Table 2. However, we could not compare the morphology of our species with R. carotae (CBS 418.65) as this species was introduced with only an asexual morph. To further support the establishment of the new taxon, we compared nucleotide differences in both LSU and ITS gene regions ( Jeewon & Hyde 2016). The nucleotide comparison between R. camporesii and R. carotae (MFLU 17-1594 and CBS 418.65), revealed 10/672 base pair differences (1.48%) in the LSU sequence and 26/560 base pairs (4.64%), including gaps in the ITS region. The difference between R. camporesii (MFLU 17-1594) and R. senecionis (MFLU 17-1635) was 5/853 base pair differences (0.58%) for LSU and 31/591 base pair differences (5.24%), including gaps for ITS. A comparison between R. camporesii (MFLU 17-1594) and R. microspora (MFLU 18-2672) showed 5/843 base pair differences for LSU and 51/598 base pair differences (8.52%) in ITS region, including gaps.

Figures

FIGURE 1. Rhexocercosporidium camporesii (MFLU 17-1594, holotype). a Apothecia on wood. b Close-up of apothecium. c Cross section of Apothecium. d Ectal excipulum e Filiform branched paraphyses. f Cylindrical ascus in congo red. g–j Cylindrical asci at different stages of maturity. k J+, ring in Melzer’s reagent. l Ellipsoidal to fusiform ascospores. Scale bars a = 500 µm, b = 200 µm, c = 50 µm, d, e = 30 µm, f–j = 20 µm, k = 5 µm, l = 10 µm.