Refers to the Balearic Islands (Spain), where the holotype was found.

Sexual morph: Stromata forming black, linear, confluent raised areas on host surface, with the longer axis broken at the apex, (500–)600–1500(–2000) µm × (200–)320–450(–500) µm (n = 20). Ascomata globose to subglobose, with flattened base, blackish brown, (120–) 140–180 (–200) µm in diameter (n = 30). Peridium 8–15 µm thick, consisting of 4–5 layers of cells arranged in textura angularis, externally dark brown, hyaline in the inner part. Ostiole single, central, 30–60 µm in diameter, with a periphysate channel 20–30 µm long. Peryphises broad, colourless. Hamathecium composed of dense hypha-like, broad septate paraphyses, deliquescing early, 4–6 µm thick. Asci 8-spored, unitunicate, clavate, broadly cylindrical, with an inconspicuous pedicel, rounded apex, thin-walled, without an apical apparatus, measuring (77–)80–98(–105) × (14–)15–19(–21) µm (n = 22). Ascospores 1–3-seriate, hyaline, apiospore smooth-walled, fusiform, elliptical, reniform, straight or curved, bicellular, wider at the center of the longest cell, measuring (23–)26–30(–32) × (7–)9–10(–12) µm (n = 35), basal cell 3–6 µm long, sometimes containing a droplet. Asexual morph: not observed. Culture characteristics: colonies flat spreading on MEA 2%, with moderate aerial mycelium, reverse withish.

Spain: Balearic Islands: Mallorca, Llucmajor, on undetermined Poaceae, 24 Jan. 2018, A. Pintos (MA-Fungi 91723 holotype, AP24118 isotype, CBS 145129 ex-type culture).

Arthrinium balearicum is related with A. descalsii, but has some genetic differences with this species having only 93% (482/518 bp) of its ITS rDNA, 99% (821/823 bp) of 28S rDNA, 97% (688/707 bp) of tef1, and 98% (406/413 bp) of tub2 similar. It is also phylogenetically close to A. phragmitis, a species with a similar ascospore size, (23–)26–30(–32) × (7–)9–10(–12) µm in A. balearicum and (22–)23–28(–30) µm × (6–)7–9(–10) µm in A. phragmitis. Unfortunately, the asexual morph of A. balearicum could not be studied to compare it with that of A. phragmitis.

Figure 3. 

A. balearicum A stromata on host; B asci C–F ascospores G colony on MEA. Scale bars: 200 µm (A); 20 µm (B); 5 µm (C–F).

Asexual morph: colonies on the host punctiform, pulvinate, 140–400 µm in diameter, blackish brown. Mycelium formed by hyaline smooth, branched hyphae, 2–5 µm in diameter. Conidiophore mother cells arising from a superficial or erumpent mycelial mat, subspherical to lageniform in shape, hyaline with brown pigments at the base, measuring (4–)5–7(–8) × (8–)9–11(–12) µm (n = 45). Conidiophores erect or ascending, simple, straight or flexuous, cylindrical, smooth-walled, colourless excepting for the thick, brown to dark brown, transversal septa, 15–100 × 3–5 µm (n = 50). Conidia fusiform or broadly spindle-shaped, smooth-walled, broader at the middle, tapering towards the narrowly rounded ends, dark brown with a hyaline rim, (37–)44–51(–55) µm in frontal view, (8–)9–11(–12) µm in side view (n = 50). Sterile cells smaller, 15–19 × 10–13 µm, and paler than conidia, bicuspidate or irregularly lobed. Culture characteristics: flat colonies spreading on MEA 2%, with moderately abundant, white cottony aerial mycelium, reverse whitish too, circular in shape with irregular edge.

The conidia of A. caricicola and A. japonicum have a similar fusiform shape and length, but differ in width ((8–)9–11(–12) µm vs 12–16(–20) µm). Conidia of A. mytilimorphum have also a similar shape, but turns out shorter and thinner (20–30 × 6–8.5 µm). The morphological characters of the syntype of A. caricicola deposited by Fries in the Herbarium of Uppsala University as Fung. Scleromyc. Suecici, fully match the specimen collected in this study. The closely related species A. sporophleum has very different lemon-shaped conidia, while those of A. curvatum var. minus are curved, and those of A. puccinioides are polygonal.

Germany: Brandenburg: south of Liberose, on dead leaves of Carex ericetorum, 14 May 2018, R. Jarling (MA-Fungi 91725).

Figure 4. 

A. caricicola A colony on host B colony on MEA C conidiophore mother cell D, E conidiophore mother cell, conidiophore bearing conidia, conidia F–H conidia I conidia with scar J lobate sterile cells. Scale bars: 200 µm (A); 5 µm (C–I); 10 µm (J). K A. caricicola syntype, colonies on host; L, M conidia.

Asexual morph: Colonies are compact, round, dark to black, 80–320 in diameter. Mycelium is composed of hyaline to pale brown smooth hyphae 2–7 µm in diameter. Conidiophore mother cells spherical to lageniform, hyaline with brown pigments at the base, measuring (4–)5–7(–8) × (4–)5–6(–7) µm (n = 30). Conidiophores cylindrical unbranched, straight or flexuous, hyaline and smooth walled, with a single brown transversal septa, measuring 30–100 × 2–4 µm. (n = 30). Conidiogenous cells cylindrical 1–1.5 × 1–1.5 µm (n = 20). Conidia borne along the sides of conidiophores, curved, rounded at the ends, brown, with a hyaline germ slit and a clearly visible scar, (8–)9–10(–11) µm long in frontal view, (5–)6–7(–8) µm in side view (n = 30). Sterile cells rounded, paler than conidia. Culture characteristics flat colonies spreading on MEA 2% with moderate aerial mycelium, reverse withish.

Arthrinium curvatum var. minus can be confused with A. curvatum var. curvatum , but conidia of var. minus measure (8–)9–10(–11) × (5–)6–7(–8) µm, while those of A. curvatum var. curvatum measure 11–15 × 6–8 µm. Gutner (1927) described Pseudoguignardia scirpi, a sexual morph of A. curvatum, later combined as Physalospora scirpi (Arx 1970). Arthrinium curvatum var. minus is closely related with A. sporophleum (with lemon-shaped conidia) and A. japonicum (with larger fusiform conidia) and to a lesser extent also with A. caricicola (with larger fusiform conidia) and A. puccinioides (with polygonal conidia). Ellis et al. (1951) described A. curvatum var. minus, a taxon with similarly shaped but smaller conidia than A. curvatum. The specimen studied in the present work matches the shape and size of conidia reported by Ellis et al. (1951) for A. curvatum var. minus, rather than those of A. curvatum var. curvatum.

Germany: Brandenburg: south of Liberose, on dead leaves of Carex sp., 28 Mar. 2018, R. Jarling (MA-Fungi 91726).

Figure 5. 

A. curvatum var. minus A colony on host B conidiophore mother cell C, D conidiophore mother cell, conidiophore bearing conidia E, F curved conidia G colony on MEA. Scale bars: 200 µm (A); 5 µm (B–F).

Named to honor the eminent mycologist Enric Descals Callisen.

Sexual morph: Stromata forming black fusiform spots that merge with each other with age, forming an erumpent black mass visible at the naked eye, 2–10 × 0.2–0.5 mm in size, with the long axis broken at the top revealing the ostioles of pseudothecia. Ascomata pseudothecia, subglobose with a flattened base, arranged in rows, brown to dark brown, 150–220 μm high × 150–250 μm wide (n = 20). Peridium with several layers of cells arranged in textura angularis, with a conspicuous ostiole 50–80 μm in diameter, periphysate. Hamathecium paraphyses hyphae-like, septate, hyaline. Asci cylindrical, clavate, with a short or indistinct pedicel, with rounded apices, measuring (73–)82–95(–111) × (16–)17–20(–23) μm (n = 30). Ascospores uniseriate to biseriate, hyaline, smooth-walled, apiosporic, composed of a large curved upper cell and smaller lower cell, fusiform to slightly curved in shape with narrowly rounded ends, guttulated, sometimes with a thick gelatinous sheath, (17–)18–22(–24) × (6–)7–9(–10) μm, and a basal cell 3–5 μm (n = 45). Asexual morph: Mycelium hyaline, septate, branched, hyphae 1.5–4.5 μm in diameter Conidiophores reduced to the conidiogenous cells. Conidiogenous cells solitary on hyphae, ampuliform, hyaline to brown, 5 × 4 μm. Conidia brown, smooth, guttulate, globose to ellipsoid (5–)7(–8) µm long (n = 20) in face view, lenticular with a paler equatorial slit and 6-7 μm long in side view (n = 10). Sterile cells elongated, sometimes mixed among conidia. Culture characteristics: ascospores germinating on MEA 2% within 24–48 h. Colonies flat, spreading, with sparse aerial mycelium, pale siena.

Arthrinium descalsii is closely related with A. phragmitis and A. balearicum. It was found in the Mediterranean grass Ampelodesmos mauritanicus, although additional samples are needed before concluding if it could be exclusively associated with this endemic host. Ascospore size is often smaller than that of A. balearicum, (23–)26–30(–32) × (7–)9–10(–12) µm, but it matches that reported in the protologue of A. phragmitis, (20–)22–24(–25) × (7–)8–9(–10) µm. However, the conidiophores of A. descalsii are reduced to conidiogenous cells, while those of A. phragmitis measure about 10–45 × 1.5–2 µm, and conidia are slightly smaller in face view, measuring (5–)7(–8) µm long in A. descalsii and up to 8–10(–11) µm in A. phragmitis.

Spain: Balearic Islands: Mallorca, es Capdella, on dead stems of Ampelodesmos mauritanicus, 31 Jan. 2018, A. Pintos (MA-Fungi 91724 holotype, AP31118A isotype, CBS 145130 ex-type culture).

Figure 6. 

A. descalsii A stromata on host B–D asci with ascospores E paraphyses F, G ascospores I, J ascospores with sheath K colony on MEA 2%; coniogenous cell giving rise to conidia; conidiogenous cells giving rise to conidia and conidia cluster G conidia. Scale bars: 200 µm (A); 10 µm (B–E); 5 µm (F–J); 5 µm (L–N).

In reference to Esporles, the village of Mallorca (Spain) where it was found.

Asexual morph: Mycelium consisting of smooth, hyaline, branched septate hyphae about 1.5–4 µm in diameter. Conidiophores reduced to conidiogeous cells. Conidiogenous cells polyblastic, aggregated in clusters on hyphae, smooth, hyaline to pale brown, ampuliform, cylindrical or lageniform, measuring 4–22 × 4–8 μm. Conidia brown, smooth, globose with a pale equatorial slit and (8–)9–12(–13) µm long in frontal view, lenticular and 6–8 μm long in side view (n = 30). Sterile cells elongated, sometimes mixed among conidia, paler than them. Culture characteristics: colonies flat, spreading, with moderate aerial mycelium, on MEA 2% surface white with yellowish patches, reverse concolour with age.

Spain: Balearic Islands: Mallorca, Esporles, on dead culms of Phyllostachys aurea, 16 July 2017, A. Pintos (MA-Fungi 91727 holotype, AP16717 isotype, CBS 145136 ex-type culture).

Arthrinium esporlense is closely related with A. xenocordella and A. kogelbergense. However, A. esporlense does not produce brown setae as A. xenocordella, a species until now known only from soil samples (Crous and Groenewald 2013). Arthrinium esporlense morphologically differs from A. kogelbergense by producing slightly bigger conidiogenous cells (4–22 × 4–8 μm vs 5–12 × 4–5 μm). These three species are genetically related (1.00 PP, 96 BP) to the group formed by A. arundinis, A. thailandicum D.Q. Dai & K.D. Hyde, A. malaysianum and the new species A. italicum proposed below.

Figure 7. 

A. esporlense A colony on MEA B–F coniogenous cell giving rise to conidia G conidia. Scale bars: 5 µm (B–G).

Sexual morph: Stromata black, fusiform, forming rows of densely arranged perithecial ascomata parallel to the main axis of the host, measuring (400–) 600–2500(–3000) × (250–)320–450(–550) µm (n = 30). Ascomata globose to subglobose, with a flattened base, blackish brown, (130–)250–290(–320) µm in diameter (n = 30). Peridium consisting of 3 or 4 layers of cells arranged in textura angularis, dark brown in the external side, hyaline in the inside, ostiole single, central, 10–30 µm in diameter, with a periphysate channel 20–35 µm long. Peryphises broad, colourless. Hamathecium composed of dense hypha-like, broad septate paraphyses, early deliquescing. Asci 8-spored, unitunicate, clavate, broadly cylindrical, pedicel indistinct, apical rounded, thin-walled, without an apical apparatus, measuring (76–) 85–98(–115) × (20–)22–26(–28) µm (n = 22). Ascospores uni- to tri-seriate, hyaline, apiosporic, smooth-walled, fusiform, elliptical, reniform, straight or curved, smooth-walled, sometimes with an internal droplet, bicellular, the widest part located in the central part of the longest cell, some ascospores have a mucose sheath covering them, (28–)32–34(–38) × (8–)9–11(–13) (n = 35) µm, basal cell 5–7 µm. Asexual morph: Mycelium branched, septate. Conidiomata on host surrounding the stromata of the sexual phase, parallel to the longitudinal axis of the stem, subepidermal, opening by longitudinal splitting of the epidermis and revealing a black conidial mass, (450–) 630–950(–1000) × (275–)345–550 (–600) µm (n = 35). Conidiophore mother cell arising from the stroma, ampuliform, lageniform, cupulate or cylindrical, sometimes with granular pigments at the apex, (5)6–10(–16) × (3–)5–7(–8) µm (n = 24). Conidiophores basauxic, polyblastic, cylindrical, hyaline to light brown, smooth or with granular pigments in all their length, straight or flexuous, septate or not, sometimes exceeding 90 μm in length × 2–4 μm wide (n = 43). Conidia globose to obovoid, dark brown, with a central scar at the base, (15–)16–20(–21) in frontal view, (14–)15–18(–19) in side view (n = 40). Sterile cells gray, irregularly angled and lobed, (15–)17–41(–42) × (10–)14–23(–25) µm (n = 30). Culture characteristics: colonies in MEA 2% flat, spreading, first white and cottony, later became dark pink, mycelium branched, septate, hyaline, reverse dark.

After the works of Samuels (1981), Sivanesan (1983), Kirk (1986) and Réblová et al. (2016), Ap. bambusae, Ap. setosa and Ap. tintinnabula, as well as Scyphospora phyllostachydis, are all considered synonyms of A. hysterinum. Arthrinium hysterinum is phyllogenetically close to A. yunnanum D.Q. Dai & K.D. Hyde, but morphologically differs from the latter because of its thinner asci (76–115 × 20–28 vs 85–100 × 30–35 μm). In addition, A. hysterinum has longer conidiophores up to 90 μm long, and lobed sterile cells while in A. yunnanum conidiophores do not exceed 50 μm, and sterile cells are lacking.

New Zealand: Waikato: Paeroa, on dead culm of Bambusa sp., 28 Feb. 1980, E.H.C. McKenzie & P.R. Johnston (ICMP 6889 ex-type culture).

Spain: Galicia: Santiago de Compostela, on dead culms of Phyllostachys aurea, 12 Jan. 2018, A. Pintos (MA-Fungi 91731, AP12118). Balearic Islands: Mallorca, Esporlas, on dead culms of Phyllostachys aurea, 29 July 2017, A. Pintos (MA-Fungi 91729, AP29717). Mallorca, Jardin Botanico de Soller, on dead culms of Phyllostachys aurea, 24 Oct. 2017, A. Pintos (MA-Fungi 91730, AP2410173). Mallorca, Soller, on dead culms of Phyllostachys aurea, 15 Mar. 2018, A. Pintos (MA-Fungi 91728, AP15318).

Figure 8. 

A. hysterinum lenticular-shaped colonies on host A stromata and conidiomata B, C asci D–G ascospores H colony on MEA I black masses of conidia in culture K, L conidiophore mother cell M rugose conidiogenous cell N–P conidia with lobate sterile cells O conidia. Scale bars: 200 µm (A); 10 µm (B, C); 5 µm (D–G); 200 µm (I); 5 µm (K, M, O); 10 µm (P).

In reference to the Iberian Peninsula, where the holotype was collected.

Sexual morph: Stromata solitary to gregarious, immersed or semi-immersed, fusiform to ellipsoid in shape, black, with the long axis broken at the top, 2–5 × 0.5–1 mm. Ascomata perithecial, subglobose with a flattened base, arranged in rows, brown to dark brown, exudating a white cirrhus of ascospores, 170–300 µm in diameter and 200–300 µm high. Peridium consisting in 3 or 4 layers of cells arranged in textura angularis. Ostiole single, central, 12–30 µm in diameter, with a periphysate channel. Hamathecium composed of dense, septate, branched paraphyses. Asci 8-spored, clavate or cylindrical, lacking an apical apparatus, shortly pedicelate, measuring (82–)90–125(–128) × (14–)15–19(–21) μm (n = 30). Ascospores uniseriate to biseriate, hyaline, smooth-walled, apiosporic, composed of a large curved upper cell and small lower cell, fusiform or slightly curved in shape with narrowly rounded ends, uniguttulated, lacking a gelatinose sheath, measuring (28–)29–34(–37) × (5–)6–8(–9) μm, and a basal cell 5–7 μm (n = 45). Asexual morph: Mycelium hyaline, septate, branched, hyphae 2–4 μm in diameter. Conidiophores reduced to the conidiogenous cells. Conidiogenous cells aggregated in clusters on hypha or solitary, ampuliform or cylindrical, 6–12 × 3 μm. Conidia brown, smooth, globose to ellipsoid (9–)10(–12) µm long (n = 30) in face view, lenticular, with a paler equatorial slit, and (6–)7(–8) μm long (n = 40) in side view. Sterile cells elongated, rolled up, sometimes mixed among conidia. Culture characteristics: ascospores germinating on MEA 2% within 24–48 h. Colonies flat, spreading, with sparse aerial mycelium, pale siena with white patches.

Portugal. Viana do Castelo: Valença do Minho, on dead culms of Arundo donax. 10 Jan. 2018, A. Pintos (MA-Fungi 91732 holotype, AP10118 isotype, CBS 145137 ex-type culture).

Arthrinium ibericum belongs to the large clade around A. sacchari, where it shows a relation with the subclade of A. phaeospermum, A. saccharicola, and the modern species A. serenense, A. camelliae-sinensis, A. jiangxiense, A. dichotomanthi, A. obovatum and A. pseudosinense. The size of conidia is more or less similar to that of A. camelliae-sinensis, where these measure about 9.0–13.5 μm in frontal view, but conidiogenous cells are a bit smaller in this species, measuring about 4.0–9.5 × 3.0–6.0 μm. Arthrinium pseudosinense has slightly smaller asci measuring 85–100 × 15–20 µm, and ellipsoid conidia covered with a mucilaginous sheath. Arthrinium saccharicola has hyphae slightly wider, about 3–5 µm. The genetic identity of A. phaeospermum is still dubious because of the lack of a proper type, but the lineages of this species in the work of Crous and Groenewald (2013) have slightly smaller conidiogenous cells measuring 5–10 × 3–5 μm, and a different iron-grey colour of colonies in MEA.

Figure 9. 

A. ibericum A ascomata with oozing ascospores B–D asci E–H ascospores I colony on MEA J–M conidiogenous cells giving rise to conidia N sterile cell with conidia O conidia. Scale bars: 200 µm (A); 10 µm (B–D); 20 µm (C); 5 µm (E–H); 5 µm (J–O).

In reference to Italy, the country where the holotype was found.

Sexual morph: Stromata solitary to gregarious, inmersed to erumpent, fusiform, with long axis broken at the top by one or two cracks, 0.5–4 × 0.2–0.5 mm (n = 20). Ascomata uniseriate or irregularly arranged beneath stromata, pseudothecial, black, globose to subglobose with a flattened base, 150–200 μm high × 230–300 μm wide. Peridium composed of 5 or 6 layers of brown cells arranged in textura angularis, with a conspicuous peryphisate ostiole. Hamathecium paraphyses hyphae-like. Asci broadly cylindrical, clavate or subglobose, pedicel indistinct, apically rounded (70–)72–93(–96) × (14–)15–18(–20) μm (n = 30). Ascospores apiosporic, clavate to fusiform with narrowly rounded ends, composed of a large upper cell and small lower cell, hyaline, smooth-walled, surrounded by a gelatinose sheath, measuring (20–)21–25(–26) × (5–)6– 9(–10) μm, basal cell 3–5 μm (n = 45). Asexual morph: Mycelium consisting of smooth, hyaline, branched, septate hyphae 1.5–4 µm in diameter. Conidiophores straight or flexuous, cylindrical, colourless except for the thick brown transversal septa, smooth-walled, 10–50 × 1–3 μm. Conidiogenous cells ampuliform, cylindrical or doliform, hyaline to brown, (3–)4–7(–9) × (1.5–)2–3(–5) μm (n = 30). Conidia brown, smooth, globose in face view, lenticular in side view, 4–6 × 3–4 μm (n = 65), with a pale equatorial slit. Culture characteristics: on MEA 2%, sparse aerial mycelia, surface dirty white, reverse pale yellowish.

Italy: Sicily: On dead culms of Arundo donax, 19 June 2016, H. Voglmayr (MA-Fungi 91733 holotype, AP221017 isotype, CBS 145138 ex-type culture).

Arthrinium italicum is phylogenetically close to A. thailandicum, and to a lesser extent to A. malaysianum. Stromata of A. thailandicum are smaller than those of A. italicum, measuring 0.45–0.99 × 0.3–0.55 mm, ascomata are perithecical, its conidiogenous cells are longer (11.5–39 × 2–3.5 μm) and branched, and conidia measure 5–9 × 5–8 μm. The conidia of A. malaysianum are similar in size, but this species does not produce conidiophores.

Spain: Balearic Islands: Mallorca, Puerto de Andratx, on dead culms of Phragmites australis, 29 Jan. 2018, A. Pintos (MA-Fungi 91734, AP29118).

Figure 10. 

A. italicum A, B stromata on host C asci D, E, G ascospores F ascospores with sheath H colony on MEA I–M conidiogenous cell giving rise to conidia N, O conidia. Scale bars: 200 µm (A, B); 5 µm (D–G); 5 µm (H–L, N, O); 10 µm (M).

Sexual morph: Stromata forming black fusiform spots, visible at the naked eye, with a long axis broken at the top revealing the ostioles of pseudothecia, 2–6 × 0.2–0.5 mm in size. Ascomata subglobose, sometimes with a flattened base, brownish to reddish brown, 150–190 μm high × 160–250 μm wide (n = 20). Peridium with several layers of cells arranged in textura angularis, with a conspicuous ostiole 50–7–80 μm diameter, periphysate. Hamathecium paraphyses not prominent, hyphae-like, septate, hyaline. Asci 8-spored, unitunicate, broadly cylindrical to clavate, with rounded apex and a short pedicel, (60–)70–100(–115) × (16–)18–20(–22) μm (n = 30). Ascospores fusiform to elliptical, with narrowly rounded ends, hyaline, with multiple guttules, surrounded by a mucilaginous sheath, (16)19–23(–24) × (6–)7–8(–10) μm, basal cell 2–5 (n = 30). Asexual morph: Mycelium consisting of smooth, hyaline, branched, septate hyphae measuring 1.5–5 µm in diameter. Conidiophores straight or flexuous, cylindrical, colourless except for the thick brown transverse septa, measuring 10–40 × 2–3 μm. Conidiogenous cells ampuliform to cylindrical, hyaline to brown, (3–)4–7(–11) × (1.4–)2–4(–5) μm (n = 30). Conidia, brown, smooth, granular, globose in face view, lenticular in side view, measuring (6–)7–8(–9) × 4–5(–6) µm, with a pale equatorial slit. Sterile cells elongated, brown. Culture characteristics: ascospores germinating on MEA 2% within 24–48 h. Colonies flat, spreading, with sparse aerial mycelium, reverse concolour with agA.

Arthrinium marii was proposed by Larrondo and Calvo (1990) who described its asexual morph. This apparently frequent species has been isolated from the atmosphere, pharmaceutical excipients, home dust, and beach sand, as well as from various plant hosts (Crous 2013). In the present work the sexual morph is described for the first time. Genetically, samples identified as A. marii seem to represent two distinct clades (Fig. 2), with differences in tub2 and tef1 genes, but it should be further investigated with additional data before concluding if these clades should be interpreted as intraspecific variability, partially isolated lineages, or fully isolated species. Similarly, the incomplete data from the type specimens of A. hispanicum and A. mediterranei do not allow one to conclude if these apparently related species represent a single taxon or even belong to A. marii.

Austria: Oberösterreich: St. Willibald, on dead culms of Phragmites australis, 10 July 2016, H. Voglmayr, (MA-Fungi 91738, AP191017).

Italy: Sicily: casa de la Monache, on dead culms of Phragmites australis, 16 July 2016, H. Voglmayr (MA-Fung 91740, APVog2).

Portugal: Viana do Castelo: Valença do Minho, on dead culms of Phragmites australis, 10 Jan. 2018, A. Pintos (AP10118A).

Spain: Balearic Islands: Mallorca, Esporlas, on dead culms of Arundo donax, 13 July 2017, A. Pintos (MA-Fungi 91735, AP13717). Ibidem., 29 July 2017, A. Pintos (AP29717). Palma de Mallorca, on Ampelodesmos mauritanicus, 11 July 2017, A. Pintos (MA-Fungi 91737, AP11717A). Palma de Mallorca, on dead culms of Phragmites australis, 26 July 2017, A. Pintos (MA-Fungi 91739, AP261017).

Figure 11. 

A. marii A stromata on host B asci C–F ascospores G colony on MEA H–I, K conidiogenous cells giving rise to conidia J conidiophore bearing conidia L conidia and sterile cells. Scale bars: 200 µm (A); 10 µm (B); 5 µm (C–F); 5 µm (H–L).

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

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.

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).

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.

Figure 12. 

A. piptatheri A colony on MEA B–K conidiogenous cells giving rise to conidia. Scale bars: 5 µm (B–K).

Asexual morph: Mycelium consisting on smooth hyaline, branched, septate hyphae measuring 1.5–5 µm in diameter. Colonies are small, rounded or ovoid, dark brown, 50–400 µm in diameter. Conidiophore mother cells subspherical, lageniform or barrel-shaped, 4–5 × 3–5 µm (n = 30). Conidiophores cylindrical, straight or flexuous, septate, hyaline excepting for the thick brown or dark brown transversal septa, 20–140 × 3–4 µm (n = 30). Conidiogenous cells cylindrical, occurring between the conidiophore septa, 0.9–1.8 µm. Conidia dark brown, smooth, polygonal with rounded angles to hemispherical, measuring (8–)9–11(–12) × 8–9 µm, with one or two concentric pale rings. Sterile cells spherical, triangular or polygonal, with refractive bodies inside, paler than conidia, 6–9 µm in diameter. Culture characteristics colonies flat spreading on MEA 2%, with moderate aerial mycelium, reverse whitish, no esporulate on culture.

Arthrinium puccinioides is the only species of Arthrinium with polygonal conida. It shows a genetic relationship with other species found in Carex sp. hosts, such as A. caricicola, A. curvatum var. minus, A. japonicum or A. sporophleum. The present sample fits the original description of A. puccinioides by Kunze and Schmidt (1823) as well as those by Ellis et al. (1951), Ellis (1965), and Scheuer (1996).

Germany: Berlin: Köpenick, Stellingdamm, on dead leaves of Carex arenaria, 26 April 2017, R. Jarling (MA-Fungi 91746, AP26418).

Figure 13. 

A. puccinioides A colony on host B colony on MEA C conidiophore mother cell D–F conidiophore bearing conidia G–H conidia in side view. Scale bars: 100 µm (A); 5 µm (C–H).

Asexual morph: Mycelium consisting on smooth hyaline branched hyphae, 2–5 µm in diameter. Colonies oval to irregular, dark blakish brown, 300–1200 × 150–650 µm. Conidiophore mother cells sub-cylindrical, hyaline to pale brown, measuring 5–7 × 5–7 µm (n = 20). Conidiophores straight to flexuous, cylindrical, hyaline except for the thick brown to dark brown transversal septa, 30–130 × 2–4 µm (n = 20). Conidia brown, smooth, lemon-shaped in face view, measuring (10–)11–14(–15) × (5–)6–8(–9) µm (n = 45), triangular with the outer edge curved and rounded angles in side view, measuring 5–8 µm thick. Sterile cells paler than conidia, subspherical or triangular, 5–8 µm wide. Culture characteristics: on MEA 2% colonies cottony, white with grey patches, reverse pale grey.

Arthrinium sporophleum is the only species of Arthrinium with lemon-shaped conidia. Kunze (1823) considered that Sporophleum gramineum represents a synonym of this species, and Cooke (1954) considered A. sporophleoides Fuckel a synonym of this species too. The only sample analyzed in the present work fits the descriptions of this species by Kunze (1823), Ellis et al. (1951), Ellis (1965) and Scheuer (1996). This sample was found in Juncus sp., but this remarkable species has been often reported from Carex sp. hosts (Ellis 1965). Interestingly, other species occurring in Carex sp. present also conidia with unusual shapes, e.g. A. puccinioides (polygonal), A. curvatum var. minus (curved), and A. caricicola or A. japonicum (fusiform).

Spain: Balearic Islands: Mallorca, Escorca, on dead leaves of Juncus sp., 21 Feb. 2018, A. Pintos 21218 (MA-Fungi 91749).

Arthrinium arundinis : Spain: Galicia: Santiago de Compostela, city garden, culms of Bambusa sp., 11 Jan. 2018, A. Pintos 11118A (MA-Fungi 91722). Arthrinium phragmitis: Spain: Balearic Islands: Mallorca, Esporles, on dead culms of Arundo donax, 29 July 2017, A. Pintos (MA-Fungi 91744, AP29717A). Ibidem., on dead stem of Phragmites australis, 3 Feb. 2018, A. Pintos (MA-Fungi 91743, AP3218). Jardin Botanico de Soller, on dead culms of Arundo donax, 24 Oct. 2017, A. Pintos (MA-Fungi 91742, AP2410172A). Puigpunyent, on dead culms of Phragmites australis, 28 Dec. 2017, A. Pintos (MA-Fungi 91741, AP281217A1). Arthrinium rasikravindrii: Spain: Balearic Islands: Mallorca, Esporlas, on dead culms of Phyllostachys aurea, 8 Aug. 2017, A. Pintos (MA-Fungi 91747, AP8817). Jardin Botanico de Soller, on dead culms of Bambusa sp., 24 Oct. 2017, A. Pintos (AP2420171). Soller, on dead culms of Phyllostachys aurea, 10 Apr. 2018, A. Pintos (MA-Fungi 91748, AP10418).

Figure 14. 

A. sporophleum A colony on host B conidiophore mother cells C–E conidiophore mother cells with conidiophore bearing conidia, F with sterile cell F–H conidia I colony on MEA. Scale bars: 100 µm (A); 5 µm (B–H).