Pleosporales » Leptosphaeriaceae

Chaetoplea

Chaetoplea (Sacc.) Clem., in Clements & Shear, Gen. fung. Edn 2 (Minneapolis): 275 (1931).

Pyrenophora subgen. Chaetoplea Sacc., Syll. fung. (Abellini) 2: 279 (1883).

Index Fungorum number: IF 959; Facesoffungi number: FoF 06401, 23 morphological species (Species Fungorum 2022), no molecular data available.

Saprobic on woody stems or herbaceous dicotyledonous. Sexual morph: Ascomata solitary, gregarious, semi-immersed to superficial, or erumpent through host tissue, uniloculate, subglobose, glabrous, brown to dark brown, ostioles central, with short papilla. Peridium thick-walled, of equal thickness, composed of dark brown to black, scleroplectenchymatous cells of textura angularis or textura globulosa. Hamathecium composed of numerous, filamentous, distinctly septate, broad cellular pseudoparaphyses, anastomosing at the apex. Asci 8-spored, bitunicate, clavate to cylindric-clavate, short pedicellate, apically rounded, with an ocular chamber. Ascospores overlapping 1–2-seriate, phragmosporous, fusiform or broadly fusiform to ellipsoidal, brown to yellowish-brown, septate, slightly constricted at the septa, smooth-walled. Asexual morph: Conidiomata pycnidial, scattered, solitary to gregarious, semi-immersed to erumpent, uniloculate, ellipsoidal to broadly fusiform with rounded apex, glabrous, dark brown to black, ostioles central, with pore-like opening. Conidiomata walls thin-walled, composed of flattened, scleroplectenchymatous cells, arranged in textura angularis to textura prismatica, brown to dark brown. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, phialidic, discrete, ampulliform, hyaline, smooth-walled, hard to distinguish from the inner wall cells. Conidia oblong to ellipsoidal, with obtuse ends, brown, uniseptate, smooth-walled (adapted from Phookamsak et al. 2014).

 Type species: Chaetoplea calvescens (Fr.) Clem.

Notes: Chaetoplea is characterised by semi-immersed to superficial, or erumpent ascomata, clavate to cylindric-clavate asci and 1–2-seriate, phragmosporous, fusiform or broadly fusiform to ellipsoidal, brown to yellowish-brown ascospores. Barr (1987, 1990) treated Chaetoplea sensu lato in Phaeosphaeriaceae. The holotype material of Chaetoplea calvescens is lost. Zhang et al. (2012) observed the isotype microslide from the Farlow Herbarium (FH) and reported only ascus and ascospore characters. Zhang et al. (2012) stated that Chaetoplea is heterogeneous and can be found on a wide range of hosts such as herbaceous stems, decorticated wood and periderm tissues. The asexual morph of Chaetoplea has been reported as Dendryphium comosum (Phookamsak et al. 2014). Webster and Lucas (1959) mentioned Microdiplodia henningsii as the asexual morph of Chaetoplea and this was accepted by Barr (1987b), but this link was not proven by molecular data. Ramaley (1995) considered Parahendersonia as the asexual morph of Chaetoplea dasylirionis and transferred Chaetoplea to Leptosphaeriaceae. Crous et al. (2006) treated Microdiplodia as the asexual morph of Karstenula and accommodated the genus in Montagnulaceae (= Didymosphaeriaceae). Phookamsak et al. (2014) examined Fries exsiccatus (Scler. Suecicae exsiccatus no. 401) from the US National Fungus Collections (BPI) and designated it as the lectotype of Chaetoplea calvescens. The authors studied the asexual morph on the same host as the lectotype, and it was characterised by oblong to ellipsoidal, brown, uniseptate, smooth-walled microdiplodia-like conidia. Phookamsak et al. (2014) placed Chaetoplea in Leptosphaeriaceae based on morphology. Currently, Chaetoplea is a distinct genus in Leptosphaeriaceae but molecular data is lacking. Fresh collections with DNA sequence data are needed to confirm the taxonomic placement of the genus. Chaetoplea requires epitypification.

 

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