Pachyphlodes coalescens Pina Paez , R.A. Healy & Cazares, 2021

Paez, Carolina Pina, Healy, Rosanne A., Guevara, Gonzalo, Orijel, Roberto Garibay, Castellano, Michael A., Cazares, Efren & Trappe, James M., 2021, Greetings from belowground: two new species of truffles in the genus Pachyphlodes (Pezizaceae, Pezizales) from Mexico, MycoKeys 82, pp. 159-171 : 159

Pachyphlodes coalescens Pina Paez, R.A. Healy & Cazares sp. nov.

Fig. 3 a-e

Type.

México, Michoacán, road Morelia-Atécuaro, Morelia , 19°36'0"N, 101°10'58.8"W, alt. 2280 m, under Quercus deserticola Trel., hypogeous, solitary, 30 September 2012, col. R. Garibay-Orijel (holotype: MEXU 26842) .

Diagnosis.

Pachyphlodes coalescens can be recognized by the brown ascomata and two-layered, thick (600-700 µm) peridium, and a gleba marbled with light yellow, meandering, sterile veins alternating with dark brown fertile veins, spores ornamented with truncated spines, that have material deposited at the tips, which accumulates and coalesces with neighboring tip material to form a broad, meandering, roughened, reticulum that hides the underlying spines, growing under Quercus .

Etymology.

Named for the process that produces the spore ornamentation: material deposited on the spine tips coalesces to form a meandering reticulum, from Latin coalecere, to grow together.

Description.

Ascomata irregularly subglobose, slightly compressed, 12 × 14 mm, surface with flat, polygonal warts with 4-6 sides, each wart about 2.5-3.0 mm broad, orange-brown when fresh (Fig. 3a ), dark reddish-brown when dried, areole 6 × 4 mm where internal sterile veins emerge. Gleba light yellow with translucent yellowish sterile veins when fresh becoming cream with light brown veins when dried (Fig. 3b ).

Peridium of two layers. Outer peridium 440-500 μm thick, composed of textura angularis, with warts up to 220 μm high, outermost cells up to 30 μm broad, walls 1 μm broad, orange-brown in 5% KOH, interior cells up to 22 μm broad with notably thinner cell walls <0.5 µm, hyaline (Fig. 3c ). Inner peridium about 175-190 μm thick, composed of hyaline, septate, interwoven hyphae 4.5-6.5 µm broad, thin-walled <0.5 μm. Paraphyses filiform, septate, with swollen tips, 200-210 × 8.75 μm, 10-14 μm broad at the apex, pale green with granular contents, thin-walled <0.5 μm. Asci 8-spored, irregularly distributed in fertile brown veins among interwoven hyphae, pyriform to cylindrical with a short pedicel, 180-195 μm long including pedicel, 40-50 μm wide, pedicel 22-26 × 10-12 μm, widening at the base, hyaline in 5% KOH, walls <0.5 µm (Fig. 3d ). Spores irregularly biseriate to uniseriate. No reaction of asci in Melzer’s reagent. Ascospores (Fig. 3e, f ) globose, hyaline to light yellow, size range including ornaments 20-23 μm, averaging 21.20 μm, spores excluding ornaments 16-18 μm, averaging 17.70 μm. Ornamentation averaging 1.80 μm high, of short capitate spines that accumulate material at the tips that coalesces to produce a nearly solid covering over the spore by maturity.

Distribution and ecology.

Ascomata hypogeous, known from Michoacán and Tlaxcala co-occurring with Quercus deserticola Trel, Quercus rugosa Née, and Q. crassifolia Humb. & Bonpl. DNA sequences have also been found in Quercus dry forests or xerophilous pine-oak forests in Libres in Puebla, Tequila volcano in Jalisco, and Cerro del Águila in Michoacán, all in central-southwestern México.

Specimens examined.

México, Tlaxcala, 1 km east of San Francisco Temezontla, Municipio Panotla , alt. 2600 m, under Quercus rugosa Née, and Q. crassifolia Humb. & Bonpl., September 20, 2007, col. E. Cázares (JT32454; GenBank EU543209 ) .

Taxonomic comments.

Pachyphlodes coalescens has a texture and peridial structure of the peridium similar to the other two species of the Marronina clade ( P. brunnea and P. marronina ) clade, but they vary in other macroscopic or microscopic characteristics. Ascomata of Pachyphlodes brunnea are dark brown to brownish black, whereas P. coalescens ascomata are orange-brown. In addition, they differ in spore size ( P. brunnea 18-22 μm vs. P. coalescens 20-23 μm), and the spore ornamentation of P. brunnea is of discreet, capitate columns, whereas in P. coalescens , it is of spines with additional material that is so thickly deposited at the apices as to form a broad, meandering perispore that nearly covers the spore surface. Pachyphlodes coalescens are similar to P. marronina , but the latter has smaller spores (19-22 μm) ornamented with coarse, mostly discreet, truncate to capitate spines, whereas P. coalescens has short spines fully connected at the tips via the material deposited at the apex of each spine (see above). The spore ornamentation of P. coalescens is similar to that of P. nemoralis Hobart, Bóna & A. Paz and P. pfisteri Tocci, M.E. Sm. & Healy, which otherwise differ strongly in color, peridium structure, and phylogenetic placement.

Figures

Figure 3. Pachyphlodes coalescens (Holotype: MEXU 26842) a ascoma fresh b gleba in cross-section c peridium in cross-section, showing a wart composed of isodiametric cells d light microscopy of asci and spores e, f SEM microscopy of spores in surface view. Scale bars: 5 mm (a, b), 100 µm (c), 10 µm (d, e), 5 µm (f).