Trimmatothelopsis mexicana K. Knudsen, Huereca, Kocourk. & Hodkova, 2023

Knudsen, Kerry, Kocourkova, Jana, Hodkova, Eva, Dart, Jason, Huereca, Alejandro & Malicek, Jiri, 2023, Three new species of Trimmatothelopsis (Acarosporales, Acarosporaceae) from southwestern North America, MycoKeys 99, pp. 251-268 : 251

Trimmatothelopsis mexicana K. Knudsen, Huereca, Kocourk. & Hodkova sp. nov.

Fig. 3

Diagnosis.

Similar to Trimmatothelopsis terricola but differing in producing long conidia (up to 13.9 × 1.5 µm).

Type.

Mexico, Nuevo León: Sabinas Hidalgo, Presa Sombretillo, on exposed siliceous boulders at the edge of dam crest, Tamaulipan thorn scrub forest with Acacia rigidula , Cordia boissieri and Prosopis glandulosa , on red sandstone, 26.3220, -99.9519, alt. 360 m, 28 Dec. 2020, A. Huereca AH-877 (holotype-BRY-C) .

Etymology.

This is the first species of the genus discovered in Mexico and is named in honor of the work of all the Mexican lichenologists in North America.

Description.

Thallus of squamules forming a dispersed to areolate pattern, 0.5-1.2 mm wide, 300-500 μm thick including stipe, replicating by division. Upper surface pale brown, epruinose, lower surface brown and ecorticate. Epicortex 10 μm thick. Cortex 20-30 μm thick, top layer brown, one cell thick, cells up to 7 μm wide, lower layer hyaline, cells mostly round 3-5 μm wide. Algal layer 70-120 μm thick, uninterrupted, dense, algal cells 8-12 μm wide. Medulla 60-100 μm thick, hyphae 0.5-1.0 μm, obscure, upper area hyaline, lower area inspersed and darker, hyphae funneling into the stipe. Apothecia usually one per squamule, sometimes two or three, sometimes with compound apothecia, disc punctiform 1-2 mm wide, rarely 4 mm wide, concave, disc brown and reddish when wetted, epruinose, sometimes with elevated apothecial crown, color of the thallus, often with a red ring around the base of apothecia. Parathecium 10-40 μm wide, merging with cortex, IKI-. Hymenium 200-220 µm high, paraphyses 1.9-2.3 μm wide, apices in brown gel cap, hymenial gel IKI+ red, hemiamyloid. Asci 110-120 × (20-)30-40 μm, ascus stain IKI+ light blue tholus and space between the outer and inner wall of the ascus before ascospores fill the asci, darker blue area in upper layers of tholus evanescent, observed once. Ascospores (3.8-)4.8-5.24-5.7(-5.8) × (2.3-)2.4-2.55-2.8(-3.1) µm (n = 20), l/b 2.1. Subhymenium ca 10-20 μm tall, IKI+ blue, fading and hard to distinguish from hymenium. Hypothecium 20-35 μm tall, IKI-, usually narrowing along the side of hymenium into the parathecium. Pycnidia 70-107 × 128-178 µm, multi-chambered, with conidiogenous cells 21-32 × 1.9-2.8 µm (n = 10), conidia variable (4.1-)5.0-8.2-11.4(-13.9) × (0.9-)1.0-1.18-1.4(-1.5) µm (n = 20), l/b 7.0. Not producing secondary metabolites.

Ecology and distribution.

On siliceous red sandstone, known only from the type locality at Nuevo León, Sabinas Hidalgo, Presa Sombretillo, at an altitude of 385 m.

Notes.

Trimmatothelopsis mexicana has the same IKI ascus stain with a light blue tholus and blue space between inner and outer layer of the ascus as in five other species of Trimmatothelopsis . The blue stain in upper tholus was observed once. It differs from all species in genus in having the longest conidia and the second longest conidiogenous cells. Trimmatothelopsis rhizobola has the longest conidiogenous cells ( Knudsen and Lendemer 2016). They are filiform, 15-20(-40) × 1 μm.

We were expecting Trimmatothelopsis mexicana in the Chihuahuan Desert in New Mexico, but did not find it. Instead we discovered another new species, T. novomexicana . Trimmatothelopsis mexicana is currently known only from the type locality. We are sure someone will collect this distinctive species in Mexico in the future, and it may occur at least in New Mexico or Texas in the United States.

Figures

Figure 3. Trimmatothelopsis mexicana, Huereca AH- 877, Holotype A areolate thallus with apothecia B apothecium with elevated crown C vertical section of apothecium D apothecial crown E hemiamyloid reaction of hymenium and amyloid reaction in tholus F sparingly anastomosed paraphyses G terminal cells of paraphyses H young ascus I young ascus in IKI J mostly biguttulate ascospores K pycnidia on the thallus L vertical section of pycnidium with three chambers M long narrowly ampulliform conidiogenous cells producing conidia N conidia. Scale bars: 500 µm (A, B, K); 200 µm (C); 100 µm (L); 50 µm (D); 20 µm (E, H, I); 10 µm (F, G); 5 µm (J, M, N).