Ceratostomella crypta Réblová, Hubka & Jurjević, 2024

Réblová, Martina, Nekvindová, Jana, Kolařík, Miroslav, Jurjević, Željko, Kolář, Michal & Hubka, Vít, 2024, Re-evaluation of Ceratostomella and Xylomelasma with introduction of two new species (Sordariomycetes), MycoKeys 110, pp. 319-360 : 319-360

Ceratostomella crypta Réblová, Hubka & Jurjević , sp. nov.

Figs 4 , 5 , 6

Etymology.

Cryptus (Latin) meaning hidden, secret; referring to cryptic nature of this species, which is morphologically indistinguishable from C. melanospora and C. sordida .

Type.

Czech Republic • South Moravian Region, Břeclav district, obora Soutok near Lanžhot ; on decaying deciduous wood; 23 Oct 2004; M. Réblová M. R. 2911 (holotype PRA -21820 !, ex-type culture CBS 131683 ) .

Description.

Sexual morph. Ascomata non-stromatic, grouped, immersed with only necks protruding, sometimes partially erumpent with bases semi-immersed. Venter 350–500 µm diam, subglobose, upright, dark brown to black, with sparse brown, septate, slightly flexuous hairs 3.5–4.5 µm wide sparsely covering the sides and bottom. Neck 100–120 µm wide, up to 860 µm long, central, cylindrical, upright, tapering at the top, sulcate along the upper half or the whole length. Ostiole periphysate. Ascomatal wall fragile to leathery, 51–72 (- 82) µm thick, two-layered. Outer layer consisting of thick-walled, dark brown, polyhedral cells with opaque walls of textura prismatica, with several cells forming the external crustose layer ca. 9–14 µm thick, cells tend to be more flattened and paler towards the interior. Inner layer consists of several rows of thin-walled, hyaline, flattened cells. Paraphyses abundant, longer than the asci, becoming partially disintegrated with age, septate, slightly constricted at the septa, hyaline, 5–9.5 µm wide, wider near the base, tapering to ca. 3.5 µm. Asci 66–77 (– 81.5) × 7.5–9.5 (– 10) µm (mean ± SD = 74.9 ± 4.4 × 8.7 ± 0.8 μm), 57.5–71.5 (– 86) µm (mean ± SD = 65.8 ± 2.6 μm) long in the sporiferous part; asci containing mostly collapsed ascospores are generally smaller in size 61–71.5 (– 74) × 7–8.5 µm (mean ± SD = 66.4 ± 2.9 × 7.8 ± 0.6 μm), 50.5–59 µm (mean ± SD = 54.3 ± 3.5 μm) long in the sporiferous part, broadly rounded to truncate at the apex, cylindrical, with a short tapering stipe, apical annulus non-amyloid, 2.5 µm wide, 1–1.5 µm high, 8 - spored. Ascospores 8.5–11 × (4 –) 4.5–5.5 µm (mean ± SD = 9.5 ± 0.7 × 5 ± 0.3 μm), ellipsoidal, slightly apiculate at both ends, brown, aseptate, smooth, with an inconspicuous germ pore at one or both ends, sometimes with one oil drop, often collapsing, obliquely uniseriate or partially overlapping within the ascus. Asexual morph. Unknown.

Characteristics in culture

(after 2 / 4 wk at 23 ° C). On CMD colonies 70–72 mm / mycelium fully covered the plate, circular, flat, margin effuse to fimbriate with a sparse growth, cobwebby, grey-brown, reverse of the same colour. On MLA colonies 50–51 mm diam / mycelium fully covered the plate, margin entire to fimbriate, circular, flat, margin entire, lanose, olivaceous grey, reverse dark olivaceous brown. On OA colonies 83–85 mm diam / mycelium fully covered the plate, circular, margin entire to fimbriate, lanose, olivaceous grey, reverse dark brown. On PCA colonies 62–64 mm diam / mycelium fully covered the plate, circular, flat, margin diffuse, cobwebby, grey-brown, reverse dark brown. Sporulation was absent on all media.

Temperature dependent growth at 30, 35, 37, 41 ° C was assessed as colony diam on MEA, PDA, and OA, respectively, after a period of two weeks: 30 ° C> 90 mm /> 90 mm /> 90 mm, 35 ° C> 90 mm /> 90 mm /> 90 mm, 37 ° C> 90 mm /> 90 mm /> 90 mm, 41 ° C 46–48 mm / 40–41 mm / 26–27 mm.

On MCA, colonies are effuse, with commonly submerged subhyaline hyphae that later become vein-like, ranging in colour from brown to dark olivaceous brown, 3–7 µm in diameter, smooth and septate, with occasional tuberose formations. These hyphae often branch to form monilioid hyphae composed of thick-walled cells, varying in shape from nearly rectangular to subglobose. Branching of monilioid hyphae often occurs at right angles, coiling hyphae are also present.

Additional specimens examined.

Czech Republic • South Moravian Region: Břeclav district, obora Soutok near Lanžhot ; on decaying deciduous wood; 23 Oct 2004; M. Réblová M. R. 2916 ( PRA -21821 , culture CBS 131684 ) . USA • South Carolina: swab from generating station ; Jul 2014; Ž. Jurjević 2471 (culture CCF 5710 = CBS 142809 ) .

Habitat and geographical distribution.

Saprobe on decaying deciduous wood in the Czech Republic; it was also isolated from a swab from generating station in the USA (South Carolina). According to GlobalFungi, the species is distributed predominantly in the temperate region of the Northern Hemisphere. Identical sequences were found in 10 samples isolated from air, sediment, soil, and water in various habitats including cropland, forest, shrubland, wetland, anthropogenic, and aquatic environments in the USA (California, Louisiana, North Carolina, and Tennessee).

Notes.

Distinguishing C. crypta from other species within the C. sordida complex presents significant challenges. Nonetheless, C. crypta can be reliably differentiated through analysis of ITS, rpb 2, and tef 1 - α sequences. Moreover, in vitro observations revealed that C. crypta demonstrates the highest growth rate within its species complex (Fig. 5 ). It is worth noting that C. crypta is unique as its mycelium completely colonizes culture plates within a two-week period when cultivated on MEA and PDA, and within a four-week period when cultivated on CMD, MLA, and PCA media at 23 ° C compared to C. melanospora and C. sordida . In addition, C. crypta grows well at 37 ° C and exhibits a growth also at 41 ° C (Fig. 6 ). The mycelium of Ceratostomella spp. in vitro is pigmented and remains sterile. In C. crypta , we observed monilioid hyphae, either branched or unbranched, growing from the septate hyphae. On MEA and MCA, monilioid hyphae are more dominant compared to those on PDA. Occasionally, these hyphae appear tuberose (budding-like), a feature that becomes more pronounced with age (Fig. 6 F ).

Ceratostomella crypta is represented by three isolates in our phylogeny. Two strains that were isolated from ascospores originate from the same locality in the Czech Republic, while the third is from the USA and is only known in its asexual state. In the Czech specimens, ascospores were observed either strongly collapsed within the asci ( CBS 131683, Fig. 4 G – K ) or mostly retaining their full shape ( CBS 131684, Fig. 4 E, F ) after rehydration, considerably impacting the ascus size. In the closely related species, such as C. melanospora and C. sordida , the difference in ascus size is less pronounced based on ascospore shape.

Figures

Figure 4. Ceratostomella crypta (A-N from holotype PRA - 21820 O from ex-type strain CBS 131683) A, B ascomata C a longitudinal section of the ascomatal wall D asci with paraphyses and ascogenous cells E-K asci with ascospores L, M paraphyses N ascospores O colony morphology at 23 ° C after 4 weeks on CMD, MLA, OA and PCA (from left to right). Images: on natural substrate (A-N). Scale bars: 500 μm (A, B); 20 μm (C, D, L, M); 10 μm (E-K, N); 1 cm (O).

Figure 5. Growth rates in vitro of Ceratostomella spp. A C. crypta CBS 131683 B C. sordida CBS 116000 C C. melanospora CBS 147993. Colonies on CMD, MLA, OA and PCA (from left to right) after two weeks. Scale bar: 1 cm.

Figure 6. Ceratostomella crypta (CCF 5710) A colony morphology at 37 ° C after 2 weeks on MCA, MEA, OA and PDA (from left to right) B, D – F pigmented monilioid hyphae on CA. C monilioid hyphae on MEA. Scale bars: 1 cm (A); 10 μm (B – F).