Antiquispora disseminans Magurno, Uszok, M. B. Queiroz & B. T. Goto, 2025

Esmaeilzadeh-Salestani, Keyvan, Queiroz, Mariana Bessa de, Mikryukov, Vladimir, Uszok, Sylwia, Goto, Bruno Tomio, Tedersoo, Leho & Magurno, Franco, 2025, Morphological and phylogenetic analysis of the early-diverging lineage of Glomeromycota suggest two new genera and recombinations in Archaeosporales, MycoKeys 124, pp. 249-273 : 249-273

Antiquispora disseminans Magurno, Uszok, M. B. Queiroz & B. T. Goto sp. nov.

Fig. 5 A – I

Etymology.

Latin, disseminans (= dissemination), referring to the species capacity for rapid and successful propagation in culture pots.

Diagnosis.

Differs from Archaeospora trappei in (i) having two layers in the inner wall, whereas A. trappei has only one; by (ii) mycorrhizal structures (spores, hypha, and vesicles) staining dark in Trypan blue, and (iii) in the nucleotide composition of SSU-ITS-LSU nrDNA.

Species description.

Acaulosporoid spores formed laterally on the neck of a sporiferous saccule (Fig. 5 H ), singly in the substrate or occasionally within roots. Spores hyaline to white (1 A 1), in maturity greyish white (1 B 1), globose to subglobose, (55 –) 60 (– 67) μm diam, rarely ellipsoid to ovoid (57 –) 62 (– 85) μm, with two walls (sw, iw) (Fig. 5 A – F, I ). Spore wall (sw) consists of two layers with 1.3–1.5 μm thick. Layer 1 (swl 1) short-lived, evanescent, hyaline, thin, 0.3–0.5 μm thick. Layer 2 (swl 2) permanent, laminated, hyaline to white (1 A 1), 0.8–1.0 μm thick. Inner wall (iw) consists of two, permanent, flexible to semi-flexible, (1.4 –) 1.5 (– 2.0) μm thick layers. Layer 1 (iwl 1) uniform, slightly pigmented (1 A 2), 0.8–1.0 μm thick. Layer 2 (iwl 2) hyaline, amorphous, 0.5–2.5 μm thick. None of the wall layers exhibits amyloid or dextrinoid reactions in Melzer’s reagent. Sporiferous saccule hyaline to subhyaline, subglobose to oblong, 15–55 × 30–75 µm diam, with an extremely delicate mono- to bi-layered wall continuous with the two outer layers of the outer spore wall (swl 1-2) and coated with adherent granular material; rarely observable in spores outside roots due to frequent collapse or detachment during extraction from the soil, except in spores with adherent soil particles or remnant root fragments; occasionally visible within root tissues, where it stains dark with Trypan blue (Fig. 5 H ). The basal attachment point of the spore is marked by a semi-persistent cicatrix-like structure formed by the spore wall (Fig. 5 H ). The spore content consists of a dense, hyaline, oily substance forming unevenly distributed droplets that appear prominently darker than the spore walls, especially when observed in Melzer’s reagent (Fig. 5 A ). A germination shield (gs) forms from the inner wall (iw) (Fig. 5 I ). This structure is difficult to observe and was only visualized laterally in spores stained in Trypan blue. Mycorrhiza with hyphae, spores, and vesicles staining dark in Trypan blue (Fig. 5 G – I ). Sporocarps unknown. Glomoid spores not detected.

Specimen examined.

The material examined was obtained from culture pots containing the host Plantago lanceolata at the University of Silesia in Katowice, Poland, originally established for the maintenance of an inoculum of Diversispora epigaea sourced from Turin, Italy. However, the spores obtained represent a species distinct from that of the intended culture target, indicating unintentional contamination. The precise origin of this contaminant cannot be definitively established. Holotype: UFRN-Fungos 3785 ; Isotype: Herbário Parque das Dunas RN 10355 .

Ecology and distribution.

In single-species cultures with Plantago lanceolata , Ant. disseminans formed typical arbuscular mycorrhizae, including spores, vesicles, and intra- and extraradical hyphae. This species exhibited an extraordinarily high success rate in pot cultures, with approximately two-thirds of single-spore cultures resulting in abundant spore production. Based on environmental DNA sequences, Ant. disseminans occurs in a variety of habitats, indicating a broad distribution. It has been detected in subtropical coniferous forest in Saltillo, Mexico; in urban soil environments in the United States; and in temperate woodland soil in Viru-Jaagupi, Estonia. These findings suggest that the species is ecologically versatile and capable of thriving across diverse climatic and habitat conditions.

Figures

Figure 5. Antiquispora disseminans. A. Intact spores with dense, oily cytoplasmic content forming irregular droplets. B – F. Spores with two distinct walls (sw, iw), each composed of two layers: swl 1–2 and iwl 1–2; G. Spores and intraradical hyphae; H. Spore (sp) formed laterally on the neck of a sporiferous saccule (sac), with a detail of the scar at the spore base; I. Spores showing wall structure with four layers and detail of the germ shield (gs); C. Spores in PVLG. A, B, D – F. Spores in PVLG + Melzer’s reagent; G – I. Spores and other structures stained in 0.1 % Trypan blue. Scale bars: 25 μm (A, G, H); 10 μm (B – F, I).