Hydropunctaria Aractina

''Hydropunctaria'' is a genus of saxicolous (rock-dwelling), crustose lichens in the family Verrucariaceae. The genus includes both aquatic and amphibious species, with members that colonise either marine or freshwater habitats. The type species, ''Hydropunctaria maura'', was formerly classified in the large genus ''Verrucaria''. It is a widely distributed species common to littoral zones. Including the type species, five ''Hydropunctaria'' lichens are considered marine species: ''H. adriatica'', ''H. amphibia'', ''H. aractina'', ''H. orae'', and ''H. oceanica''.

Taxonomy

''Hydropunctaria'' was circumscribed in 2009 by Christine Keller, Cécile Gueidan, and Holger Thüs, with ''Hydropunctaria maura'' assigned as the type species.

Description

The thallus of ''Hydropunctaria'' is crustose, with a form ranging from continuous (more or less unbroken) to rimose or areolate. In some species the texture of the thallus is somewhat gelatinous. Documented thallus colours include yellowish-brown, green, and dark grayish olive to black. The upper cortex is only weakly separated into distinct layers; microscopically, it comprises cortical cells with a diameter typically smaller than the fungal cells from the algal layer. The uppermost layer of cortical cells, when present, often contain yellowish to brown or olive-blackish pigments; this characteristic, however, is not always consistent, as evidenced by the colourless specimens sometimes collected from shaded sites. Black dots (''punctae'') are sometimes visible at the surface of the thallus—more readily so in wet thalli. The layer of algal cells is not clearly differentiated from the upper cortex, although generally they are usually arranged in vertical columns, occasionally interrupted by black punctae. The medulla is paraplectenchymatous (fungal tissue with a cellular structure superficially like parenchyma of vascular plants) and is sometimes very thin or absent, often replaced by a black carbonaceous layer that interrupted by isolated black punctae or columns.

Perithecia (flask-shaped ascomata opening by a pore, or ostiole) are immersed (or partially so) in the thallus. The involucrellum refers to the upper, often exposed covering or cap external to the excipulum and usually distinct from it. In ''Hydropunctaria'', the involucrellum is black, often with a rough or uneven upper surface, and it can be of several forms: apical (where the involucrellum occurs only around the ostiole, but extends some distance laterally) to dimidiate (where the involucrellum covers only the upper portion of the perithecium) or entire (where the involucrellum completely surrounds the perithecium). The excipulum (the cup-shaped layer of tissue surrounding the hymenium) is either pale with a brown ostiole or completely pigmented.

''Hydropunctaria'' species have eight-spored asci that are bitunicate (i.e., with two functional ascal wall layers). Its ascospores are simple (i.e., lacking septa), with a rounded or ellipsoid shape and a length usually more than 12 μm.

Species

*'' Hydropunctaria adriatica''
*'' Hydropunctaria alaskana'' – Alaska
*''Hydropunctaria amphibia''
*'' Hydropunctaria aractina''
*''Hydropunctaria maura''
*''Hydropunctaria oceanica''
*''Hydropunctaria orae''
*''Hydropunctaria rheitrophila''
*''Hydropunctaria scabra''
*''Hydropunctaria symbalana''

Species interactions

Lichenicolous (lichen-dwelling) lichens recorded growing on ''Hydropunctaria'' include '' Sirenophila ovis-atra'' and ''Flavoplaca microthallina''.

References

{{Taxonbar, from=Q10528934

Verrucariales
Lichen genera
Taxa described in 2009
Eurotiomycetes genera
Taxa named by Cécile Gueidan