Dominikia paraminuta Blaszk., Niezgoda & B. T. Goto 2025, sp. nov.

Dominikia paraminuta Błaszk., Niezgoda & B. T. Goto sp. nov. Fig. 2 A – H Specimens examined. Poland. Pomeranian Province, spores from single-species cultures established from spores extracted from trap pot cultures inoculated with rhizosphere soil and root fragments of Ammophila arenaria from the Hel Peninsula maritime dunes (54 ° 45 ' 31 " N, 18 ° 30 ' 38 " E and 54 ° 41 ' 58 " N, 18 ° 40 ' 36 " E), 14 Aug 2012, J. Błaszkowski (holotype: slide with spores Z + ZT Myc 0067480; isotypes: slides with spores nos. 3979–3987, LPPDSE). Etymology. Latin, paraminuta, referring to D. minuta, the phylogenetic sister of this new species. Diagnosis. Differs from D. minuta, the phylogenetic sister, in (i) morphometric features of spores and their spore wall, (ii) the spore wall structure, (iii) phenotypic properties of spore wall layer 1, and (iv) nucleotide composition of sequences of the 45 S nuc rDNA region (see “ Discussion ” for details). Description. Forming loose to compact hypogeous clusters with five to ca. 25 randomly distributed spores and sterile hyphae (Fig. 2 A – D). Spores glomoid, arising blastically at tips of subtending hyphae (Fig. 2 A, B, F, G) branched from a parent hypha continuous with a mycorrhizal extraradical hypha. Spores hyaline; globose to subglobose; (23 –) 31 (– 39) µm diam; rarely ovoid to oblong, 14–33 × 26–71 µm; with one subtending hypha (Fig. 2 A – G). Spore wall composed of three hyaline layers (layers 1–3; Fig. 2 D – G). Layer 1, forming the spore surface, uniform (without visible sublayers), semi-permanent, (0.8 –) 1.3 (– 2.0) µm thick when smooth, often with local thickenings, (1.2 –) 2.1 (– 3.8) µm thick, randomly distributed on the spore surface, rarely strongly or completely sloughed off in aged spores (Fig. 2 D – G). Layer 2 laminate, permanent, smooth, (1.0 –) 1.4 (– 2.0) µm thick, consisting of very thin, <0.5 µm, sublayers tightly adherent to and not separating from each other even in vigorously crushed spores (Fig. 2 D – G). Layer 3 uniform, permanent, smooth, ca. 0.6–0.8 µm thick, usually tightly adherent to the inner surface of layer 2 and, therefore, difficult to detect. Layers 1–3 do not stain in Melzer’s reagent (Fig. 2 E – G). Subtending hypha hyaline; straight or recurved, usually cylindrical to funnel-shaped, rarely slightly constricted at the spore base, (3.8 –) 5.7 (– 9.5) µm wide at the spore base (Fig. 2 A, B, F, G). Wall of subtending hypha hyaline; (1.6 –) 2.2 (– 2.9) µm thick at the spore base; composed of three layers continuous with spore wall layers 1–3 (Fig. 2 F, G). Pore (1.0 –) 1.9 (– 5.8) µm diam, usually open (Fig. 2 F), very rarely occluded by a curved septum connecting the inner surfaces of subtending hyphal wall layer 3; septum 0.4–0.6 µm thick, located ca. 2.0 µm below the spore base (Fig. 2 G). Sterile hyphae hyaline, (2.8 –) 4.4 (– 5.2) µm wide (Fig. 2 B, C). Germination unknown. Ecology and distribution. In the field, D. paraminuta probably lived in arbuscular mycorrhizal symbiosis with roots of A. arenaria that colonized maritime sand dunes near Chałupy and Jastarnia on the Hel Peninsula, northern Poland. However, no molecular analyses were performed to confirm this assumption. In single-species cultures with P. lanceolata as host plant, D. paraminuta formed mycorrhiza with arbuscules, vesicles, and intra- and extraradical hyphae (Fig. 2 H). These structures stained clearly [pale violet (16 A 3) to deep violet (16 E 8)] in 0.1 % Trypan blue. Phylogenetic analyses with the 45 S alignment used in this study and environmental sequences with> 96 % identity to 45 S sequences of D. paraminuta, revealed by BLASTn, indicated that D. paraminuta was previously recognized in grasslands and unspecified sites in China (data not shown).