Tremellales » Cryptococcaceae » Kwoniella

Kwoniella mangrovensis

Kwoniella mangrovensis Statzell, Belloch & Fell 2008, in Statzell-Tallman, et al., FEMS yeast research, 8, 103-113 (2008)

Etymology: Named for the type habitat of the species the mangroves, which occur in tropical and subtropical marine intertidal environments.

Diagnosis: After 3 days at 22 oC in 5% malt extract broth (MEB), the cells are ovoid, ellipsoid to globose, 38 mm×36 mm, and they may be single or with one to two attached multilateral buds and in short chains. Sediment is present after 1 month. Neither a ring nor a pellicle forms on the surface of the broth. After 1 month on 5% malt extract agar at 22 1C, the colony is tannish-white, smooth, glistening and raised. The texture is butyrous. The margins are entire and hyphae are rarely formed. After 1 week at 22 1C on a corn meal agar (CMA) Dalmau plate, pseudohyphae are not formed; after 21 days, sparse rudimentary pseudohyphae can occur. True hyphae with false clamp connections are present in one strain (ML 3895). After 2 weeks on potato dextrose agar, the colony is light tan and a brown pigment has diffused into the solid medium. Sexual reproduction: Pairs of compatible strains, when mixed on CMA at 22 oC for 5 days, develop sparse hyphae with one or more clamps at the septa. Phragmobasidia form within 514 days on the apical hyphal cell and intercalary or laterally on the hyphae. Some hyphae grow at an angle after basidial formation, which results in an angular growth pattern. The basidia are polymorphic: lageniform (7 mm×27 mm) with longitudinal and transverse septa; navicular (1013 mm×1921 mm) with one to three transverse septa; four-celled globose (1319 mm) and ovoid with longitudinal to oblique and transverse septa. The globose basidia occur singly, in pairs and in chains. Germination usually occurs within 1 week when 1-month-old basidia in agar blocks are transferred to 2% water agar. Basidiospores are globose (411.3 mm) or ovoid to cylindrical (610 mm×7.511.3 mm). The basidiospores are passively released and may bud to form colonies in the agar. Basidiospores may also bud while attached to the basidium. The mating system appears to be unifactorial biallelic, as represented by one strain of mating type A and five strains of mating type α. Mating reactions were not obtained with some strains, which are considered to belong to the species based on sequence analyses. These non-mating strains could represent a separate sexual incompatibility factor as part of a multiple allelic system. The mating reaction, on Bacto CMA with additional 2% Bacto agar, results in more extensive hyphal development with masses of yeast cells, which appear to be the result of basidiospore replication.

Index Fungorum Number: IF533966


Figure 1. Location of collection sites (Mangrove Cay, Alans Pensicola, Manjack Cay, Cross Key,  Shroud Cay and Pipe Creek) in the Bahama Islands.

Figure 2. Kwoniella mangrovensis. (a) Globose basidia formed on clamped hyphae, 2 weeks at 22 oC after mating pair was mixed on CMA. Olympus differential interference contrast. (c) Vegetative cells of CBS 8507 grown at 22 oC for 3 days in 5% malt extract broth. Olympus differential interference contrast. (e) A lageniform basidium with an inflated base, 1 month at 22 oC after mating pair was mixed on CMA. A transverse septum is visible. Wild phase contrast. (b) Globose basidia six days at 22 oC after mating pair was mixed on CMA. Olympus differential interference contrast. (d) A lageniform basidium on a clamped hypha, 1 month at 22 oC after mating pair was mixed on CMA. Olympus differential interference contrast. (f) Basidiospores, one budding, remain attached to the apex of a lageniform basidium. One month at 22 oC after mating pair was mixed on CMA. Wild-phase contrast.