Molecular systematics of the marine Dothideomycetes

Abstract

Phylogenetic analyses of four nuclear genes, namely the large and small subunits of the nuclear ribosomal RNA, transcription elongation factor 1-alpha and the second largest RNA polymerase II subunit, established that the ecological group of marine bitunicate ascomycetes has representatives in the orders Capnodiales, Hysteriales, Jahnulales, Mytilinidiales, Patellariales and Pleosporales. Most of the fungi sequenced were intertidal mangrove taxa and belong to members of 12 families in the Pleosporales: Aigialaceae, Didymellaceae,Leptosphaeriaceae, Lenthitheciaceae, Lophiostomataceae, Massarinaceae,Montagnulaceae, Morosphaeriaceae, Phaeosphaeriaceae, Pleosporaceae, Testudinaceae and Trematosphaeriaceae. Two new families are described: Aigialaceae and Morosphaeriaceae, and three new genera proposed: Halomassarina, Morosphaeria and Rimora. Few marine species are reported from the Dothideomycetidae (e.g. Mycosphaerellaceae, Capnodiales), a group poorly studied at the molecular level. New marine lineages include the Testudinaceae and Manglicolaguatemalensis in the Jahnulales. Significantly, most marine Dothideomycetes are intertidal tropical species with only a few from temperate regions on salt marsh plants (Spartina species and Juncus roemerianus), and rarely totally submerged (e.g. Halotthia posidoniae and Pontoporeia biturbinata on the seagrasses Posidonia oceanica and Cymodocea nodosum). Specific attention is given to the adaptation of the Dothideomycetes to the marine milieu, new lineages of marine fungi and their host specificity.

Keywords: Dothideomycetes; ecology; marine fungi; multi-locus; new genera; systematics.

Fig. 1.

RAxML tree of marine Dothideomycetes with bootstrap support values for maximum likelihood and maximum parsimony above the nodes. The values below the nodes are Bayesian posterior probalities. Relevant clades are highlighted in colour.

Fig. 1.

RAxML tree of marine Dothideomycetes with bootstrap support values for maximum likelihood and maximum parsimony above the nodes. The values below the nodes are Bayesian posterior probalities. Relevant clades are highlighted in colour.

Fig. 1.

RAxML tree of marine Dothideomycetes with bootstrap support values for maximum likelihood and maximum parsimony above the nodes. The values below the nodes are Bayesian posterior probalities. Relevant clades are highlighted in colour.

Fig. 2.

(p. 162) Morphological features of marine Dothideomycetes. A. Immersed lenticular ascomata beneath clypeus of Carinispora nypae. B. Apothecium of Patellaria cf. atrata (Patellariales). C. Broadly conical ascomata of Halotthia posidoniae. D. Immersed ascomata of Helicascus nypae. E. Globose ascoma of Pontoporeia biturbinata. F. Immersed ascomata of Quintaria lignatilis. Released asci (arrow) from ostiole. G. Mature ascomata of Manglicola guatemalensis (Jahnulales). H. Tangential section of Helicascus nypae through stroma with several loculi. I. Longitudinal section (l.s.) of Manglicola guatemalensis ascoma with asci and pseudoparaphyses. J. Pontoporeia biturbinata, non-ostiolate ascoma, asci originating at the periphery of a hemispherical basal pulvinus. K. Longitudinal section through ascoma of Verruculina enalia. Asci. L–U. Ascus tip of Manglicola guatemalensis. Ascospores show the apical appendage (arrow) in ascus. M. Ascus tip of Salsuginea ramicola, consisting of a large distinctive ocular chamber and prominent ring (arrows). N. Clavate ascus of Quintaria lignatilis with apical plate. O. Clavate ascus of Quintaria lignatilis, with biseriate ascospores, in Nomarski and Quartz. P. Ovoidal or ellipsoidal ascospores in cylindrical asci of Acrocordiopsis patilii. Q. Clavate to long-cylindrical ascus of Carinispora nypae. R. Clavate ascus of Patellaria cf. atrata. S. Subcylindrical asci with pseudoparaphyses of Helicascus nypae. T. Clavate asci of Falciformispora lignatilis (Trematosphaeriaceae). U. Broadly clavate ascus of Pontoporeia biturbinata. V–AH. Ascospores of marine Dothideomycetes: V. Carinispora nypae. Cylindrical and multiseptate ascospore with keel-like mucilaginous sheath (arrows). W. Falciformispora lignatilis. Fusiform ascospores surrounded by thin mucilaginous sheath and single scythe-like appendage (arrow) at the base. X. Salsuginea ramicola. Ovoid, dark brown ascospore with hyaline apical germ pores. Y. Manglicola guatemalensis. Fusiform ascospore with lager, pale brown apical cell and hyaline turbinate basal cell. Z. Halotthia posidoniae. Ellipsoidal, dark brown ascospores, darker around septum. AA. Verruculina enalia. Ellipsoidal, dark brown ascospore, 1-septate. AB. Helicascus nypae. Obovoidal ascospore with persistent mucilaginous sheath. AC. Mauritiania rhizophorae. Fusiform ascospore, 9–13-distoseptate. AD. Patellaria cf. atrata. Clavate ascospore, 5–7-septate. AE. Julella avicenniae. Muriform ascospores with dilated sheath (arrows), straining in ink. AF. Halomassarina (Massarina) thalassiae. Ellipsoidal ascospores with gelatinous sheath (arrows). AG. Morosphaeria (Massarina) velataspora. Fusiform to ellipsoidal ascospores, 3-septate with mucilaginous sheath (arrows). AH. Morosphaeria (Massarina) ramunculicola. Fusiform ascospores with fully dilated mucilaginous sheath (arrows). Habitat: A, D, G, H, I, L, Q, S, V, Y, AB. On the surface of Nypa fruticans. B, F, K, M–P, R, X, AA, AC–AD, AF–AH. On mangrove wood. C, E, J, U, Z. On rhizomes of Posidonia oceanica. T, W. On oil palm (Elaeis guineensis). AE. On Avicennia spp. Scale bars: A–C, E–H = 500 mm; D = 1000 mm; I = 250 mm; K = 200 mm; J = 150 mm; L–Z, AB, AF–AH = 20 mm; AA, AC–AE = 10 mm.

Fig. 3.

Morphological features of marine Dothideomycetes in the Aigialaceae and Coronopapilla mangrovei. A. Aigialus grandis. Immersed ascomata with ascospores (arrow) released from ostiole. B–E. Longitudinal section (l.s.) through ascomata of Aigialus grandis (A), A. parvus (B), A. mangrovis (C) and A. rhizophorae (D). F. A. parvus. Surface wood showing ascoma with thick peridium. G. A. parvus. Sagittal section through ascoma. H. Ascocratera manglicola. Crater-like ascomata with released ascus (arrow) from the ostiole. I. Ascocratera manglicola. l.s. of ascoma filled with gelatinous matrix. J. Coronopapilla mangrovei. Surface view of ascomata. K. Rimora (Lophiostoma) mangrovei. Broadly oblong ascomata. L. Aigialus grandis. Asci with apical refractive ring (arrows) and ascospores. M. Coronopapilla mangrovei. Ascus tip, thick-walled with ocular chamber. N–T. Ascospores of marine Dothideomycetes in Aigialaceae: N. Aigialus grandis. Broadly fusiform (front view), muriform ascospores with drop of mucilage from end cells. O. Aigialus parvus. Ellipsoidal to broadly fusiform (front view), muriform ascospores with a gelatinous cap around apical and subapical cells (arrows). P. Aigialus mangrovis. Ellipsoidal to fusiform (front view), muriform ascospores. Q. Aigialus rhizophorae. Broadly fusiform (front view), muriform ascospores. R. Ascocratera manglicola. Ellipsoidal ascospores, initially 1-septate, later becoming 3-septate with gelatinous sheath (arrow). S. Rimora (Lophiostoma) mangrovei. Fusiform ascospore with gelatinous sheath (arrow). T. Coronopapilla mangrovei. Ellipsoidal ascospore. Habitat A–T. On mangrove wood. Scale bars: A, D–G, J–K = 500 mm; B–C, H = 250 mm; L, N–S = 25 mm; M, T = 10 mm.