Revisiting Salisapiliaceae

Abstract

Of the diverse lineages of the Phylum Oomycota, saprotrophic oomycetes from the salt marsh and mangrove habitats are still understudied, despite their ecological importance. Salisapiliaceae, a monophyletic and monogeneric taxon of the marine and estuarine oomycetes, was introduced to accommodate species with a protruding hyaline apical plug, small hyphal diameter and lack of vesicle formation during zoospore release. At the time of description of Salisapilia, only few species of Halophytophthora, an ecologically similar, phylogenetically heterogeneous genus from which Salisapilia was segregated, were included. In this study, a revision of the genus Salisapilia is presented, and five new combinations (S. bahamensis, S. elongata, S. epistomia, S. masteri, and S. mycoparasitica) and one new species (S. coffeyi) are proposed. Further, the species description of S. nakagirii is emended for some exceptional morphological and developmental characteristics. A key to the genus Salisapilia is provided and its generic circumscription and character evolution in cultivable Peronosporales are discussed.

Keywords: Estuarine oomycetes; Halophytophthora; Salisapilia; mangroves; new taxa; phylogeny.

Fig. S1.

Phylogenetic tree based on ITS sequences. The primary phylogenetic tree was inferred using Minimum Evolution (ME), with bootstrap support values from ME and Maximum Likelihood, and posterior probabilities from Bayesian Inference, in the respective order. (-) indicates unsupported alternating topology or bootstrap value and posterior probability of ≤ 50 / 0.8, respectively. The scale bar indicates the number of nucleotide substitutions per site.

Fig. S2.

Phylogenetic tree based on LSU sequences. The primary phylogenetic tree was inferred using Minimum Evolution (ME), with bootstrap support values from ME and Maximum Likelihood, and posterior probabilities from Bayesian Inference, in the respective order. (-) indicates unsupported alternating topology or bootstrap value and posterior probability of ≤ 50 / 0.8, respectively. The scale bar indicates the number of nucleotide substitutions per site.

Fig. 1.

Phylogenetic tree based on concatenated ITS and LSU alignments based on Minimum Evolution (ME) inference, with bootstrap support values from ME and Maximum Likelihood, as well as posterior probabilities from Bayesian Inference, in the respective order. (-) indicates support below 50 % (bootstrap) or 0.8 (posterior probability), or alternating but not strongly supported topology (support below 70 % bootstrap or 0.9 posterior probability). The scale bar indicates the number of nucleotide substitutions per site.

Fig. 2.

Salisapilia bahamensis NBRC 32256. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E, F. Mature, vacuolated sporangia, (inset figure, sporangium showing hyaline apical plug). Scale bars: A–D. = 30 mm, E, F. = 20 µm.

Fig. 3.

Salisapilia coffeyi NBRC 32557. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E. Immature sporangium. F, G. Mature sporangia, (inset figure) sporangium showing hyaline apical plug. H. Empty sporangium; inset, elevated or umbonate basal plug. Scale bars: A–D = 30 mm, E–H = 20 µm.

Fig. 4.

Salisapilia elongata NBRC 100786. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Mature sporangium; hyaline apical plug (inset). D. Mature sporangium releasing zoospores through a tubular vesicle. Scale bars: A, B = 30 mm, C, D. = 20 µm.

Fig. 5.

Salisapilia epistomia NBRC 32617. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E–F. Mature sporangia; hyaline apical plug (inset, Fig. 4E). Scale bars: A–D. = 30 mm, E, F. = 20 µm.

Fig. 6.

Salisapilia masteri NBRC 32604. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C, D. Mature sporangia. Scale bars: A, B = 30 mm, C, D = 20 µm.

Fig. 7.

Salisapilia mycoparasitica NBRC 32966. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E, F. Mature sporangia. Scale bars: A–D = 30 mm, E–F = 20 µm.

Fig. 8.

Salisapilia nakagirii CBS 127947. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E. Immature sporangium. F–I. Mature sporangia, (inset figure) modified shape of a sporangium. H. Empty sporangium. I. Mature sporangium with two discharge tubes. Scale bars: A–D = 30 mm, E–I = 20 µm.

Fig. 9.

Salisapilia sapeloensis CBS 127946. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E. Mature sporangium. F, G. Oogonia. Scale bars: A–D = 30 mm, E–G = 20 µm.

Fig. 10.

Salisapilia tartarea CBS 208.95. Colony patterns on A. Vegetable juice agar. B. Potato carrot agar. C. Peptone yeast glucose agar. D. Potato dextrose agar. E, F. Mature sporangia. Scale bars: A–D = 30 mm, E, F = 20 µm.

Fig. 11.

Ancestral trait reconstruction of the papilla and hyaline apical plug for Elongisporangium, Globisporangium, Halophytophthora, Phytophthora, Phytopythium, Pythium, and Salisapilia. White-coloured branches represent lineages with papillate sporangia bearing a hyaline apical plug; blue – papillate sporangia with no hyaline apical plug; yellow – semi-papillate sporangia with no hyaline apical plug; black – non-papillate sporangia. The scale corresponds to species divergence relative to nucleotide substitution rates based on the Bayesian phylogenetic inference.