Trochila bostonensis Quijada & Haelew, 2021

Gomez-Zapata, Paula Andrea, Haelewaters, Danny, Quijada, Luis, Pfister, Donald H. & Aime, M. Catherine, 2021, Notes on Trochila (Ascomycota, Leotiomycetes), with new species and combinations, MycoKeys 78, pp. 21-47 : 21

Trochila bostonensis Quijada & Haelew sp. nov. Fig. 3

Diagnosis.

Differs from Trochila craterium and T. laurocerasi in its host ( Apocynaceae ), sizes of asci (57-65.5 × 5-6 µm) and ascospores (6.2-7.2 × 2.6-2.8 µm), and the inamyloidity of its ascus apex.

Type.

Holotype: USA, Massachusetts, Boston Harbor Islands National Recreation Area, Plymouth County, Great Brewster Island, 42.3310722°N, 70.8977667°W, alt. 10 m a.s.l., 16 Oct 2017, leg. D. Haelewaters, J.K. Mitchell & L. Quijada, on hollow dead stem of Asclepias syriaca ( Gentianales , Apocynaceae ), FH:BHI-F0974. Ex-holotype sequences: isolates BHI-F0974a (1 apothecium, SSU: MT873949, ITS: MT873947, LSU: MT873952, rpb2: MT861181, tef1: MT861183) and BHI-F0974b (1 apothecium, SSU: MT873950, ITS: MT873948, LSU: MT873953, rpb2: MT861182, tef1: MT861184).

Etymology.

Trochila bostonensis - referring to Boston, Massachusetts, the locality of the type collection.

Description.

Apothecia erumpent singly or in groups of 2-3, protruding from the bark by lifting and rolling outward the host periderm, sessile on a broad base, closed and barely visible when dry, rehydrated 0.4-1.1 mm diam., 0.1-0.2 mm thick; mature flat to slightly cupulate, dark grayish red brown (47.D.gy.r.Br) to black (267.Black). Margin toothed and lighter than the disc, apothecia star-shaped, with 3-6 teeth of 0.1-0.3 mm in length, each tooth deep yellowish brown (75.deepyBr). Asci *(46.5-)55.5-66.5(-73) × (5.5-)6.0-6.5(-7.0) µm, †(50.5-)57-65.5(-66) × (4.5-)5.0-6.0 µm, 8-spored, cylindrical, pars sporifera *30-52 µm; apex rounded to subconical, inamyloid (IKI, KOH-pretreated or not), slightly thick-walled at apex, lateral walls thin; base slightly tapered and arising from croziers. Ascospores *(6.3-)6.7-7.7(-8.6) × 2.7-3.4 µm, †(5.8-)6.2-7.2 × 2.6-2.8 µm, ellipsoid-cuneate, inequilateral, ends rounded or subacute, aseptate, hyaline, smooth, thick-walled, oligoguttulate, containing 2-5 grayish yellow (90.gy.Y) oil drops (LBs), 1-2.4 µm diam., OCI = (45-)60-75(-90)%. Paraphyses slightly to medium clavate, terminal cell *(17.5-)18-23(-29.5) × 3-4 µm, secondary cells *(8-)9-10(-11) × 2.5-3 µm, lower cells *(7.5-)8.5-10.5(-11.5) × 2.5-3 µm, unbranched, thin-walled, smooth, with one or several cylindric to globose refractive drops (VBs, not present after KOH-pretreated), *3.5-14 × 2-3.5 µm. Medullary excipulum 17.5-54 µm thick, grey yellowish brown (80.gy.yBr), upper part of textura porrecta, lower part dense textura intricata, cells with tiny globose deep yellow (85.deepY) refractive drops (VBs). Ectal excipulum of thin-walled textura globulosa - angularis at base and lower flanks, dark yellowish brown (78.d.yBr) to dark brown (59.d.Br), (40-)55-78 µm thick, cells *(7.0-)9.5-13(-15.5) × (3.0-)5.0-8.5(-10) µm; at upper flanks and margin of textura prismatica, 30-40 µm thick, cells *(5.5-)6.5-7.5(-8.5) × 2.5-3.5 µm, entirely without drops and slightly gelatinized, cells slightly thick-walled with irregular patches of dark brown exudates in areas of mutual contact, cortical cells in flanks covered by amorphous refractive deep yellow (88.d.Y) granular exudates, at margin some cells protruding like short hairs (*6.5-14 × 2.5-3.5 µm). Asexual state unknown.

Notes.

Trochila bostonensis is the only species of the genus found on a member of Apocynaceae (Table 2 ). It was growing in the outer layer of a dead stem of Asclepias syriaca , which had fallen on the ground. The host was close to the shore in a shrubby thicket of Rhus . There are two similar species. Trochila laurocerasi has wider asci (6.0-8.0 µm vs. 4.5-6.0 µm) and larger ascospores (6.3-10 × 2.5-4.6 µm vs. 5.8-7.2 × 2.6-2.8 µm) compared to T. bostonensis . Ascus and ascospore length are similar in T. bostonensis and T. craterium , although ascospores are slightly larger in T. craterium . The two species mostly differ in the width of their asci (7-12 µm in T. craterium vs. 4.5-6.0 µm in T. bostonensis ). We used the measurements in dead state to compare T. bostonensis with other species in the genus (see Table 2 ).

Figures

Figure 3. Morphological features of Trochila bostonensis (holotype collection FH: BHI-F 0974) a 1 - 3, a 5 fresh apothecia a 4 dried apothecia b 1 excipular tissues in median section b 2 cells at the base b 3 cells at the upper and lower flank c 1, c 2 paraphyses d 1, d 2 asci d 3 ascus pore with inamyloid reaction d 4 crozier at ascus base e 1 - e 6 ascospores. Mounted in: Congo Red (c 2, d 2, d 4, e 3, e 5), H 2 O (b 1 - b 3, c 1, d 1, e 1, e 2), KOH (e 4), MLZ (d 3, e 6). Scale bars: 500 µm (a 1 - a 5); 50 µm (b 1); 10 µm (b 1, b 2, c 1, c 2, d 1 - d 4, e 1 - e 6).