Pleosporales » Morosphaeriaceae

Aquihelicascus

Aquihelicascus W. Dong, H. Zhang & Doilom

Index Fungorum number: IF557806; Facesoffungi number: FoF08721

Etymology: referring to the aquatic habitat and its similarity to Helicascus

 

Saprobic on submerged wood. Sexual morph: Pseudostromata scattered, comprising brown to black fungal material growing in cortex of host cells, uni- or multi-loculate, flattened at the basal region, horizontally arranged under the pseudostroma, carbonaceous or coriaceous, visible on the host surface as blackened ostiolar dots. Locules immersed, compressed subglobose to lenticular or sometimes triangular, with ostiolate papilla. Ostiole central, rounded, periphysate. Peridium comprising several layers of thin-walled angular cells, hyaline inwardly and dark at the outside, fusing with the host cells. Pseudoparaphyses numerous, cellular, hyaline, indistinctly septate, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, clavate, long pedicellate, endoascus uncoiled, apically rounded, with an indistinct or distinct, trapezoidal ocular chamber. Ascospores mostly biseriate, sometimes overlapping uniseriate, straight, or slightly curved, ellipsoidal to fusiform, with rounded ends, 1-septate, almost symmetrical, constricted at the septum, hyaline, smooth, thin-walled, lacking a mucilaginous sheath or appendage. Asexual morph: Undetermined.

 

Type species: Aquihelicascus thalassioideus (K.D. Hyde & Aptroot) W. Dong & H. Zhang

 

Notes: Aquihelicascus is introduced to accommodate one new combination A. thalassioideus and two new species A. songkhlaensis and A. yunnanensis. Aquihelicascus differs from Helicascus in having clavate asci with uncoiled endoascus, and biseriate, ellipsoidal, symmetrical, hyaline ascospores with rounded ends. In contrast, Helicascus has subcylindrical asci with coiled endoascus, and uniseriate, obovoid, asymmetrical, brown ascospores with apiculate ends (Kohlmeyer 1969; Hyde 1991; Preedanon et al. 2017). All Aquihelicascus species were collected from freshwater habitats, whereas Helicascus species are from marine habitats. Aquihelicascus and Helicascus clustered separately in phylogenetic analyses (Zhang et al. 2013; Luo et al. 2016; Preedanon et al. 2017; Dong et al. 2020) which supports the placement of two different genera. Aquihelicascus species have hyaline ascospores and are morphologically very similar. Among them, A. songkhlaensis possesses two-loculate pseudostromata and A. thalassioideus has the widest peridium. The phylogenetic analysis and single gene comparison can easily separate them.

 

List of freshwater Aquihelicascus species:

Aquihelicascus songkhlaensis W. Dong, H. Zhang & K.D. Hyde

Freshwater distribution: Thailand (Dong et al. 2020)

Aquihelicascus thalassioideus (K.D. Hyde & Aptroot) W. Dong & H. Zhang

Freshwater distribution: Australia (Hyde and Aptroot 1998), Brunei (Hyde and Aptroot 1998), China (Tsui et al. 2000; Ho et al. 2001; Luo et al. 2004), French West Indies, Martinique (Zhang et al. 2015), Peru (Shearer et al. 2015), Japan (Tanaka et al. 2015), Philippines (Hyde and Aptroot 1998), Thailand (Kurniawati et al. 2010; Zhang et al. 2013; Dong et al. 2020)

Aquihelicascus yunnanensis W. Dong, H. Zhang & K.D. Hyde

Freshwater distribution: China (Dong et al. 2020)

 

Key to freshwater Aquihelicascus species

1. Pseudostromata multi-loculate............................................. A. songkhlaensis

1. Pseudostromata uni-loculate....................................................................... 2

2. Peridium 15–25 μm thick......................................................... A. yunnanensis

2. Peridium up to 70 μm thick................................................... A. thalassioideus

 

References

Dong W, Wang B, Hyde KD, McKenzie EHC, Raja HA, Tanaka K, Abdel-Wahab MA, Abdel-Aziz FA, Doilom M, Phookamsak R, Hongsanan S, Wanasinghe DN, Yu XD, Wang GN, Yang H, Yang J, Thambugala KM, Tian Q, Luo ZL, Yang JB, Miller AN, Fournier J, Boonmee S, Hu DM, Nalumpang S, Zhang H (2020) Freshwater Dothideomycetes. Fungal Divers 105:319–575. https://doi.org/10.1007/s13225-020-00463-5

Ho WH, Hyde KD, Hodgkiss JI, Yanna (2001) Fungal communities on submerged wood from streams in Brunei, Hong Kong, and Malaysia. Mycol Res 105:1492–1501

Hyde KD (1991) Helicascus kanaloanus, Helicascus nypae sp. nov. and Salsuginea ramicola gen. et sp. nov. from intertidal mangrove wood. Bot Mar 34:311–318

Hyde KD, Aptroot A (1998) Tropical freshwater species of the genera Massarina and Lophiostoma (ascomycetes). Nova Hedwigia 66:489–502

Kohlmeyer J (1969) Marine fungi of Hawaii including the new genus Helicascus. Can J Bot 47:1469–1487

Kurniawati E, Zhang H, Chukeatirote E, Sulistyowati L, Moslem MA, Hyde KD (2010) Diversity of freshwater ascomycetes in freshwater bodies at Amphoe Mae Chan, Chiang Rai. Cryptogam Mycol 31:323–331

Luo J, Yin J, Cai L, Zhang KQ, Hyde KD (2004) Freshwater fungi in Lake Dianchi, a heavily polluted lake in Yunnan, China. Fungal Divers 16:93–112

Luo ZL, Yang J, Liu JK, Su HY, Bahkali AH, Hyde KD (2016) Two new species of Helicascus (Morosphaeriaceae) from submerged wood in northern Thailand. Phytotaxa 270:182–190

Preedanon S, Klaysuban A, Suetrong S, Promchoo W, Gundool W, Sangtiean T, Sakayaroj J (2017) Helicascus mangrovei sp. nov., a new intertidal mangrove fungus from Thailand. Mycoscience 58:174–180

Shearer CA, Zelski SE, Raja HA, Schmit JP, Miller AN, Janovec JP (2015) Distributional patterns of freshwater ascomycetes communities along an Andes to Amazon elevational gradient in Peru. Biodivers Conserv 24:1877–1897

Tanaka K, Hirayama K, Yonezawa H, Sato G, Toriyabe A, Kudo H, Hashimoto A, Matsumura M, Harada Y, Kurihara Y (2015) Revision of the Massarineae (Pleosporales, Dothideomycetes). Stud Mycol 82:75–136

Tsui KM, Hyde KD, Hodgkiss IJ (2000) Biodiversity of fungi on submerged wood in Hong Kong streams. Aquat Microb Ecol 21:289–298

Zhang H, Hyde KD, Abdel-Wahab MA, Abdel-Aziz FA, Ariyawansa HA, Ko TWK, Zhao RL, Alias SA, Bahkali AH, Zhou D (2013a) A modern concept for Helicascus with a Pleurophomopsis-like asexual state. Sydowia 65:147–166

Zhang JQ, Zhou YP, Dou ZP, Fournier J, Zhang Y (2015) Helicascus unilocularis sp. nov., a new freshwater pleosporalean ascomycete from the Caribbean area. Mycol Prog 14:1–8

 

Recent Genus

1
Neochlamydotubeufia
Neohelicomyces

Recent Species

Neohelicomyces submersus
Neohelicomyces hyalosporus
Neohelicomyces grandisporus