Rhadinomyces pallidus Thaxt.

Santamaria, Sergi & Pedersen, Jan, 2021, Laboulbeniomycetes (Fungi, Ascomycota) of Denmark, European Journal of Taxonomy 781, pp. 1-425 : 242-245

Rhadinomyces pallidus Thaxt.

MB#193503

Figs 54 , 105C

Proceedings of the American Academy of Arts and Sciences 28: 180 ( Thaxter 1893). – Corethromyces pallidus (Thaxt.) Thaxt. ( Thaxter 1912a: 180) [MB#433859] (nec Corethromyces pallidus Speg. (1917: 493) [MB#516952], nomen praeoccupum changed to C. stereocephali Thaxt. (1931: 218) [MB#278848]). –

Type: [Not designated] [Ind. loc.] “On Lathrobium punctulatum Lee. and L. angulare Lee , Massachusetts. On L. fulvipenne Grav. , Germany”; FH.

Rhadinomyces cristatus Thaxt. ( Thaxter 1893: 180) [MB#193337]. – Corethromyces cristatus (Thaxt.) Thaxt. ( Thaxter 1912a: 180) [MB#433857]

Diagnostic features

Cell II bearing 1–2(–3) perithecia or their initials, often on opposite sides. Above the cell II, 1–2 ± elongated cells bear upper corner cells in one side or on opposite sides giving rise to short branchlets bearing series of flask-shaped antheridia ( Fig. 54F ). Higher on the axis a similar cell forms the base of the appendage which consists of few to many variably elongated simple branches. [Detailed descriptions: Thaxter 1896; Majewski & Sugiyama 1985; Santamaria 1989; Majewski 1994b]

Distribution and hosts

Known from several countries in Europe, USA, and Japan ( Santamaria et al. 1991; Majewski 2008). Recent records are from Latvia ( De Kesel & Krastina De Kesel 2006, as R. cristatus ), Belgium ( De Kesel & Gerstmans 2011, as R. cristatus ), Sweden ( Huggert 2010, as R. pallidus ). Grows on Lathrobium and related genera, as Tetartopeus Czwalina, 1888 (Col. Staphylinidae Paederinae ).

Collections examined from Denmark

On Lathrobium brunnipes (Fabricius, 1792) (Col. Staphylinidae Paederinae ) DENMARK – Østjylland (EJ) • Grejsdal syd for Hornstrup ; 55°44.791′ N, 9°33.051′ E; NG37; 8 Mar. 2014; JP 752; JP det.; ZMUC C-F-123246 • Hald Ege ; 56°24.287′ N, 9°20.550′ E; NH25; 19 Oct. 2013; JP 798; JP det.; ZMUC C-F-123293 • Kjellerup ; 56°17.282′ N, 9°26.197′ E; NH23; 16 Oct. 2014; JP 321; JP det.; ZMUC C-F-122799 • Lindholm Hoved i Mossø ; 56°2.772′ N, 9°42.809′ E; NH41; 18 Jan. 2015; JP & H. Liljehult 512; JP det.; ZMUC C-F-122995 . – Fyn (F) • Rishave ; 55°33.475′ N, 10°24.013′ E; NG85; 19 Apr. 2018; JP 1068; JP det.; ZMUC C-F-123585 . – Lolland, Falster, Møn (LFM) • Lysemose ved Maribo ; 54°46.971′ N, 11°28.959′ E; PF57; 7 May 2017; JP 648; JP det.; ZMUC C-F-123137 • ibid.; 4 Jun. 2018; JP 1132; JP det.; ZMUC C-F-123655 . – Nordøstsjaelland (NEZ) • Fruebjerg i Strøgårdsvang ; 55°58.539′ N, 12°16.659′ E; UC30; 18 Oct. 2018; JP 1217; JP det.; ZMUC C-F-123744 • Gurre Vang ; 56°1.470′ N, 12°29.486′ E; UC41; 14 Apr. 2017; JP 271; JP det.; ZMUC C-F-122750 • Indelukket ved Frederiksborg Slot ; 55°56.191′ N, 12°17.861′ E; UC30; 19 Mar. 2017; JP 670; JP det.; ZMUC C-F-123159 • Mølleå ved Farum Lillevang ; 55°49.093′ N, 12°18.496′ E; UB38; 24 Feb. 2018; JP 990; JP det.; ZMUC C-F-123497 • Naerum ; 55°49.077′ N, 12°32.686′ E; UB48; 29 Apr. 2017; JP 401; JP det.; ZMUC C-F-122884 • Risby ; 55°41.112′ N, 12°19.625′ E; UB37; 21 Mar. 2019; J. SØgaard Hansen 1462; JP det.; ZMUC C-F-124013 • Skodsborg Dam i Jaegersborg Hegn ; 55°49.068′ N, 12°33.937′ E; UB48; 18 Nov. 2018; JP 1243; JP det.; ZMUC C-F-123770 • Stampeskov ved Rådvad ; 55°48.332′ N, 12°33.138′ E; UB48; 14 Apr. 2013; JP 785; JP det.; ZMUC C-F-123280 • ibid.; 23 Mar. 2017; JP 468; JP det.; ZMUC C-F-122952 . – Nordvestjylland (NWJ) • Nord for Landting ved Vinderup ; 56°30.049′ N, 8°45.384′ E; MH86; 19 Jan. 2015; JP 558; JP det.; ZMUC C-F-123044 . – Nordvestsjaelland (NWZ) • Nordbredden af Skarresø ; 55°39.425′ N, 11°22.998′ E; PG47; 1 May 2013; JP 847; JP det.; ZMUC C-F-123342 • Nordøstbredden af Tissø ; 55°35.612′ N, 11°18.461′ E; PG46; 1 May 2013; JP 762; JP det.; ZMUC C-F-123256 . – Sydsjaelland (SZ) • Denderup Sø i Denderup Vaenge ; 55°15.075′ N, 11°57.366′ E; PG82; 9 Jun. 2019; JP 1472; JP det.; ZMUC C-F-124052 • Holmegårds Mose ; 55°17.685′ N, 11°47.928′ E; PG73; 31 Mar. 2019; JP 1408; JP det.; ZMUC C-F-123954 • Krobaek i Sjolte Skov ; 55°10.772′ N, 12°0.863′ E; UB11; 17 Feb. 2019; JP 1380; JP det.; ZMUC C-F-123921 • Sorø, Kristiansminde ; 55°25.115′ N, 11°35.209′ E; PG64; 22 Jul. 2013; H. Enghoff 309; JP det.; ZMUC C-F-122788 • ibid.; 1–15 Aug. 2013; JP 524; JP det.; ZMUC C-F-123008 • Villa Gallina i Hesede Skov ; 55°16.335′ N, 11°56.850′ E; PG82; 8 Mar. 2015; JP 478; JP det.; ZMUC C-F-122962 . – Vestjylland (WJ) • Velling ; 56°3.078′ N, 8°18.596′ E; MH51; 16 Dec. 2018; JP 1261; JP det.; ZMUC C-F-123789 .

On Lathrobium fulvipenne (Gravenhorst, 1806) (Col. Staphylinidae Paederinae ) DENMARK – Sydsjaelland (SZ) • Østerskov ved Langebaek ; 54°59.572′ N, 12°6.715′ E; UA19; 3 Jan. 2019; JP 1300; JP det.; ZMUC C-F-123834 .

On Lathrobium geminum Kraatz, 1857 (Col. Staphylinidae Paederinae ) DENMARK – Nordvestjylland (NWJ) • Nord for Landting ved Vinderup ; 56°30.049′ N, 8°45.384′ E; MH86; 19 Jan. 2015; JP 557; JP det.; ZMUC C-F-123043 . – Vestjylland (WJ) • Velling ; 56°3.078′ N, 8°18.596′ E; MH51; 16 Dec. 2018; JP 1262; JP det.; ZMUC C-F-123790 .

On Tetartopeus quadratus (Paykull, 1789) (Col. Staphylinidae Paederinae ) DENMARK – Østjylland (EJ) • Klostermølle ; 56°2.432′ N, 9°41.629′ E; NH41; 18 Jan. 2015; JP 449; JP det.; ZMUC C-F-122934 . – Nordøstsjaelland (NEZ) • Damhusmosen ; 55°41.119′ N, 12°28.169′ E; UB47; 26 Apr. 1896; F. de Tengnagel Dry0124; F. de Tengnagel det.; ZMUC C-F-124191 • Naerum ; 55°48.976′ N, 12°32.253′ E; UB48; 2 May 1946; Johs. Petersen Dry0122; Johs. Petersen det.; ZMUC C-F-124189 . – Sydsjaelland (SZ) • Hulemose Sø ; 55°0.214′ N, 11°58.466′ E; PF89; 29 Apr. 1917; Chr. Engelhart Dry0123; Chr. Engelhart det.; ZMUC C-F-124190 .

On Tetartopeus terminatus (Gravenhorst, 1802) (Col. Staphylinidae Paederinae ) DENMARK – Nordøstsjaelland (NEZ) • Boserup ; 55°39.746′ N, 12°2.173′ E; UB17; 19 Sep. 1935; Johs. Andersen Dry0118; Johs.Andersen; ZMUC C-F-124185 • Frederiksdal ; 55°46.873′ N, 12°26.858′ E; UB48; May? 1850; leg. unknown Dry0121; det. unknown; ZMUC C-F-124188 . – Sydsjaelland (SZ) • Munkeskov ved Bjerrede ; 55°23.115′ N, 12°0.768′ E; UB14; 13 Sep. 1954; U. Kornerup Dry0120; U. Kornerup det.; ZMUC C-F-124187 .

Other material examined

Type of Rhadinomyces pallidus

UNITED STATES • “ Rhadinomyces pallidus , slide from FH, #4591, barcode 00313731, type, on Lathrobium sp. , from Kittery Point , Maine, York County ( USA), 08-1892 ”; FH[00313731] [includes three mature thalli in fair condition. ( Fig. 54A )]

Remarks

First record from Denmark. This may be regarded as a variable species with roughly defined characters or as a collective species including several, not yet established species. The position of the primary septum has not been described. Two to three cells may be found above cell II; these form the thallial axis and the base of the appendage. The lowermost of these cells seems to be reasonably accepted as cell III but when a second cell is present above, with corner cells and branchlets bearing antheridia, a new difficulty appears, viz., identifying this new cell as the result of a cell III division, or as corresponding to the proper basal cell of the primary appendage ( Majewski 1994b).

Thaxter (1896: 305–307) seemed not to be very convinced about the segregation of R. pallidus from R. cristatus and even about the separation of the genus Rhadinomyces from Corethromyces . The characteristics distinguishing R. pallidus and R. cristatus are undeniably confusing. Some authors have considered them conspecific ( Siemaszko & Siemaszko 1932; Balazuc 1973b) but others, as Majewski & Sugiyama (1985) distinguished R. pallidus from R. cristatus because in the former all parts of the thallus are distinctly shorter and paler, and because the antheridial branchlets arise only on the anterior side of the receptacle. Majewski (1994b) followed this criterion, and although he seemed to agree with the uncertainty concerning distinguishing both taxa he concluded that both species definitely differ by means of features displayed in his key, i.e.,: (1) R. cristatus – perithecia (including initials) typically on opposite sides of cell II; distal cells of receptacle and basal cells of appendage form corner cells on opposite sides; cell VI much shorter than the combination of cell III and basal cell of appendage; (2) R. pallidus – perithecia formed on one side of the thallus, posterior side of receptacle and appendage being sterile; cell VI about of the same length or longer than cell III and basal of appendage taken together.

Aware of the confusion, we decided to request the loan of the type slides from FH (see above under other material examined). According to the curatorial services, only one slide associated with the genus Rhadinomyces exists, labelled as the type for Rhadinomyces pallidus , whereas there are no clues about R. cristatus . The thalli in the borrowed slide are in fair condition and consist of three thalli ( Fig. 54A ). Unfortunately, its study does not help us to clarify the status of these two species.

Supported by the study of the very abundant material collected from Denmark, we conclude that it is impossible to separate the two species only with the available morphological characters. The variability is great and the limits between different forms become blurred. We challenge the reader to distinguish the two species with the images that we have included in Fig. 54 .

Figures

Fig. 54. Rhadinomyces pallidus Thaxt. A. Mature thallus from type slide kept in FH; cell II is labelled. B–E, G–I. Mature thalli showing variability. F. Branch with antheridia in detail. Scale bars: A–E, G–I = 50 µm; F = 25 µm. Photographs from slides FH4591 (A) (type), ZMUC C-F-123008 (B, H–I), ZMUC C-F-122788 (C, E–F), ZMUC C-F-123585 (D), ZMUC C-F-122952 (G).

Fig. 105. Habitus of hosts with fungi. Some thalli are zoomed in, and others are encircled. A. Perigona nigriceps with thalli of Laboulbenia manubriolata on dorsal side of the elytra. B. Brachygluta fossulata with a few thalli of Cryptandromyces elegans on the apex of the abdominal segments, on the hind coxa and the tip of the left hind tibia. C. Lathrobium brunnipes with thalli of Rhadinomyces pallidus on various parts of the body. Scale bars: 1 mm. (Photos: Aslak Kappel Hansen).