Arthrinium piptatheri Pintos & P. Alvarado.

Pintos, Angel, Alvarado, Pablo, Planas, Juan & Jarling, Rene, 2019, Six new species of Arthrinium from Europe and notes about A. caricicola and other species found in Carex spp. hosts, MycoKeys 49, pp. 15-48 : 15

Arthrinium piptatheri Pintos & P. Alvarado. sp. nov. Fig. 12

Etymology.

Named after Piptatherum , the host plant from which it was first isolated.

Diagnosis.

Asexual morph: Mycelium consisting of smooth, hyaline, branched, septate hyphae measuring 1-4 µm in diameter. Conidiophore mother cells hyaline to brown, aggregated in clusters or solitary on hyphae, ampuliform, cylindrical or doliform, 4-11 × 2-5 µm, growing above one or several hyaline cylindrical cells. Conidiophore reduced to a conidiogenous cell. Conidiogenous cells basauxic, polyblastic, sympodial, cylindrical, discrete, sometimes branched, smooth-walled, measuring 6-27 × 2-5 μm (n = 25). Conidia globose to ellipsoidal, pale brown to brown, with a thin hyaline germ-slit, 6-8 × 3-5 μm (n = 30). Sterile cells eloganted, brown, sometimes mixed among conidia, 13-16 × 4-5 μm (n = 30). Culture characteristics: on MEA 2%, colonies flat, spreading, with sparse aerial mycelium, reverse concolour with agar.

Type.

Spain: Balearic Islands: Mallorca: Llucmajor, on dead stems of Piptatherum miliaceum , 4 Aug. 2017, A. Pintos (MA-Fungi 91745 holotype, AP4817A isotype, CBS 145149 ex-type culture).

Notes.

Arthrinium piptatheri is genetically close, but genetically distinct from A. marii , A. sacchari , A. guizhouense , A. hispanicum , A. mediterranei , A. longistromum D.Q. Dai & K.D. Hyde, and to a lesser extent A. pseudospegazzinii (Fig. 2) and the clade around A. phaeospermum (Fig. 1). The incomplete genetic data available is probably the cause behind the lack of significant support for some of these taxa. Morphologically, A. piptatheri differs from A. marii because of its sympodial, branched conidiogenous cells. Arthrinium guizhouense has shorter conidiogenous cells (3.5-8.0 μm). Finally, some sequences of Ap. montagnei are related also with this group (Fig. 2), but this species is considered the sexual morph of A. arundinis , with a very different genetic profile in Crous and Groenewald (2013), so its actual identity should be further investigated.