Rhabdogloeopsis Petr., Annls mycol. 23(1/2): 52 (1925)
Facesoffungi number: FoF 07574
Ascomycota, genera incertae sedis
Habit on Abies balsamea and A. fraseri (Pinaceae). Sexual morph: undetermined. Asexual morph: Conidiomata pale brown, acervular, hypophyllous, solitary to gregarious, subepidermal, immersed, linear or oval, unilocular, glabrous. Ostiole absent. dehiscence by irregular splits of the overlapping host epidermis. Conidiomatal wall composed of thin-walled, pale brown to hyaline cells of textura angularis in the basal part. Conidiophores arising from the upper cells of the basal stroma, hyaline, cylindrical, branched, septate, smooth-walled. Conidiogenous cells hyaline, holoblastic, sympodial, cylindrical, slightly curved, integrated, indeterminate, smooth-walled, with 1–3 sympodial, unthickened proliferations towards the apices. Conidia hyaline, fusiform, sometimes broader at the middle zone, obtuse at the apex, slightly truncate the base, aseptate, smooth-walled, guttulate (adapted from Morgan-Jones et al. 1972c, Sutton 1980).
Type species: Rhabdogloeopsis balsameae (Davis) Petr., Annls mycol. 23(1/2): 52 (1925)
Notes: Petrak (1925) proposed Rhabdogloeopsis to accommodate a segregated species Gloeosporium balsameae Davis as R. balsameae which was collected form Abies balsamea in Wisconsin. This genus was re-described by Nag Raj and Morgan-Jones (1973). While the illustration is purported to be of Rhabdogloeopsis balsameae it is, in fact, of asexual morph of Rhabdocline weirii (= Rhabdogloeum pseudotsugae), and it was amended by Sutton (1980) and Nag Raj (1993). Rhabdogloeopsis is characterized by holoblastic conidiogenous cells with 1–3 sympodial, unthickened proliferations towards the apices and fusiform, aseptate conidia (Bonar 1962, Sutton 1980). The holoblastic, sympodial, conidiogenous cells in Rhabdogloeopsis closely resemble Hypocline. The later has eustromatic conidiomata with upper and basal wall cells of textura angularis producing cylindrical conidia, which differs from the acervular conidiomata producing fusiform conidia in Rhabdogloeopsis (Sutton 1980, Morgan-Jones et al. 1972c).
Bonar (1962) and Korf (1962) made a connection between asexual morph Rhabdogloeopsis balsameae (≡ Gloeosporium balsameae) and sexual morph Stegopezizella balsameae (= Sarcotrochila balsameae (Davis) Korf), based on both morphs occurring on same host. However, this connection has not been proven by culture study. Thus Rhabdogloeopsis is accepted as a legitimate name following Kirk (2013) and Wijayawardene et al. (2017b), rather than a synonym of Sarcotrochila (Index Fungorum 2019). It is necessary to obtain fresh material of type species and to make cultural connections in other species.
Distribution: USA (Sutton 1980).
Rhabdogloeopsis balsameae (redrawn from Morgan-Jones et al. 1972c) a Conidia. b Vertical section of conidioma. c Conidiophores, conidiogenous cells and conidia.
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.