Scutellospora deformata A. Guillén, F.J. Serrano-Tamay, J.B. Peris & Arrillaga, I., 2021

Guillén, Alberto, Serrano-Tamay, Fernando Javier, Peris, Juan Bautista & Arrillaga, Isabel, 2021, Scutellospora deformata (Scutellosporaceae), a new species of Gigasporales from the Mediterranean sand dunes of Spain, Phytotaxa 502 (1), pp. 67-78 : 72-73

Scutellospora deformata A. Guillén, F.J. Serrano-Tamay, J.B. Peris & Arrillaga, I. , sp. nov. ( Fig. 4 )

MycoBank:—MB839727

Diagnosis:—Differs from other Scutellospora spp . mainly in the phenotypic characters related with outer, middle and inner wall as well as in the nucleotide composition of sequence of the LSU and SSU-ITS1- 5.8S nrDNA region.

Type:— SPAIN. Valencia: Sueca (El Perelló), in rhizosphere of E. farctus in habitat 2120, 39°17’11´´N; 0°16´49´´W, elev., 4m 15 Aug 2015, A. Guillén (holotype VAL_Myco 1635 !, isotypes VAL_Myco 1636–37 ! ).

Description:— Spores originate at the top or side of a bulbous sporogenous cell. Spores ( Fig. 4a ) pastel yellow (rarely is it possible to observe white spores), irregular, 129.4 × 276.6–182.7 × 413.7 μm width × length, rarely globose or subglobose. Subcellular structure of spores ( Fig. 4b–i ) consists of an outer, middle and inner wall. Outer wall ( Fig. 4b–d, f–h ) composed of three layers. Layer 1 (OWL1; Fig. 4b–c ) semi-permanent, smooth, hyaline to light yellow, 0.8–1.7 μm thick. Layer 2 (OWL2; Fig. 4b–c ) laminate, smooth, dark yellow, 3.5–14.0 μm thick. Layer 3 (OWL3; Fig. 4b–c ) flexible, smooth, concolorous with OWL2 or slightly lighter in color, and often difficult to observe as it is closely adherent to OWL2, 0.6–1.6 μm thick. Middle wall (MWL1-2; Fig. 4b–c, f–h ) composed of two hyaline layers, flexible, MWL1: 0.4–0.8 μm thick;MWL2: 0.4–0.9 μm thick. Inner wall (IWL1-2; Fig. 4b–c, d, f–h ) composed of two hyaline layers, flexible, IWL1: 0.5–1.4 μm thick; and IWL2: 0.5–1.6 μm thick. In Melzer´s reagent, OWL2 and inner wall stain red. OWL2 loses the red stain over time (at least 6 years after mounting) ( Fig. 4c, f–g ). Germination shield ( Fig. 4h–i ) hyaline to pastel yellow, violin shaped, 24.9 × 117.9–25.4 × 146.8 μm wide × long, simple or composed, slightly incised border although with large folds. Often germ pores (1–5) at the shield periphery. Sporogenous cell ( Fig. 4a, d–e ) formed terminally on a septate hypha continuous with a mycorrhizal extraradical hypha, pastel yellow, bulbous, 36.7 × 42.4–83.2 × 79.2 μm wide × long, with or without ramification. Wall of sporogenous cell ( Fig. 4e ) composed of three layers continuous with outer wall spore, 1.4–4.0 μm thick at the spore base. Outer wall layer 1 hyaline, smooth. Quite difficult to see. Outer wall layers 2 and 3 pastel yellow to bright yellow. Auxiliary cells not observed.

Mycorrhizal associations

In the field, S. deformata was found in the rhizosphere of E. farctus , A. arenaria , O. maritimus and E. spinosa in Mediterranean sand dunes from Spain.

No single-species culture was obtained.

Etymology:—Latin, deformata , refering to the characteristic irregular shape of spores.

Distribution and habitat:—Spores of S. deformata were found on 6 sites along Mediterranean sand dunes: La Garrofera (39°21´26´´N; 0°18´55´´W)El Perelló (39°17’11´´N; 0°16´49´´W), Les Palmeres(39°15´42´´N; 0°15´55´´W) El Dosser (39°11´26´´N; 0°13´25´´W), Sant Antoni (39°09´14´´N; 0°14´25´´W), and Burguera (38°56´00´´N; 0°05´50´´W) during 2014–2016. Burguera and El Perelló were the sites where the frequency of spores of S. deformata was highest, while the other sites had significantly lower frequency ( Guillén et al. 2019). On the other hand, mobile dunes had a higher frequency of spores of S. deformata than embryonic dunes ( Guillén et al. 2019). In field samples it is possible to find S. deformata alone (e.g., El Perelló) or with undescribed Gigasporaceae , and other AMF species such as Diversispora valentina Guillén et al. 2020 , D. aurantia (Błaszk., Blanke, Renker & Buscot) C. Walker & A. Schüssler , Corymbiglomus corymbiforme Błaszk. & Chwat (2012: 274) , Glomus ibericum (2020: 822) , Septoglomus mediterraneum and Funneliformis pilosus (2020: 825) ( Guillén et al. 2019, 2020a, b).

Figures

FIGURE 4. Spores of Scutellosora deformata. a. Scutellosporoid and irregular spores (glsp and isp, respectively). b–h. Outer wall with three layers (OWL1-3); middle and inner wall with three layers each (MWL1-2; IWL1-2). a, d–e. Sporogenous cell (spc) and sporogenous wall layers (SpWL1-3). h–i. Germination shield (gsh); several lobes (lo) that are separated by folds (f) and germinal pore (gp). c. IWL2 and IWL3 totally stained by PVLG + Melzer’s reagent (1:1) 6 years later after mounting. g. Outer (OWL2) and inner wall (IWL1-2) stained (partially and totally, respectively) few days after mounting. Scale bars: a= 200 μm, b–f, h= 20 μm, g, i = 50 μm. Photos by: Alberto Guillen.