Phylogenetic and morphological assessment of two new species of Amniculicola and their allies (Pleosporales)

Abstract

Two new species of Amniculicola, A. immersa sp. nov. and A. parva sp. nov. from submerged wood in a freshwater environment in Denmark and France are respectively described and illustrated. In addition, partial 28S rDNA sequence data is analysed to investigate their phylogenetic relationships with other pleosporalean taxa. All presently known Amniculicola species, A. immersa, A. lignicola and A. parva, form a robust clade together with the anamorphic species Anguillospora longissima, Spirosphaera cupreorufescens and Repetophragma ontariense. These six species, which are all from freshwater and mostly from Europe, constitute a well-supported group containing Pleospora rubicunda and Massariosphaeria typhicola. This putative monophyletic assemblage may represent an aquatic group in the Pleosporales. It is also pertinent that all five ascomycete taxa in this group stain their host substrates purple.

Keywords: anamorphs; freshwater fungi; phylogeny; pseudoparaphyses; rDNA.

Fig. 1

Amniculicola immersa (from holotype). a. Ascomata on host surface; b. habit section of ascomata. Note the purple colour in the ascomata and substrate; c. asci in pseudoparaphyses; d, e. ascospores with sheath; f. ascus; g. dehiscent ascus. c, e–g in water; d in Indian ink. — Scale bars: a = 0.5 mm; b = 200 μm; c–g = 20 μm.

Fig. 2

a–c. Amniculicola immersa (from holotype). a. Section of ascoma. Note the thick apical wall; b. section of ascoma. Note the purple colour in the ascomata and substrate; c. section of ascoma. Note the peridium structure. — d, e. Amniculicola parva (from holotype). d. Section of ascoma; e. section of the peridium near base. Note the tubercule. — Scale bars: a, b = 0.1 mm; c–e = 50 μm.

Fig. 3

Amniculicola parva (from holotype). a, b. Ascomata on host surface. Note the purple substrate; c. habit section of ascoma; d. ascospores with sheath; e. asci in thin anastomosing pseudoparaphyses; f. ascus. d in Indian ink; e in cotton blue; f in water. — Scale bars: a = 0.5 mm; b, c = 0.1 mm; d–f = 10 μm.

Fig. 4

Maximum parsimony tree generated from partial 28S rDNA and with gaps as missing data. Designated outgroup is Diaporthe phaseolorum (AY346279). Bootstrap support values above 50 % (based on 1 000 replicates) are shown on nodes, and those lower than 50 % are marked as *. Newly generated sequences are marked as * on the right top corner of the GenBank accession numbers.

Fig. 5

a. Massariosphaeria typhicola (from IFRD 2018). a. Asci in pseudoparaphyses. — b, c, d. Pleospora rubicunda (from IFRD 2017). b. Ascus; c. ascomata on the host surface; d. ascospore with wide sheath. a, b in water; d in Indian ink. — Scale bars: a, b, d = 20 μm; c = 0.5 mm.