Monoicomyces brachiatus Santamaria & Pedersen 2021, sp. nov.
Creators: name: Santamaria, Sergi
name: Pedersen, Jan
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Laboulbeniomycetes
Laboulbeniales
Laboulbeniaceae
Monoicomyces
Monoicomyces brachiatus

description: Monoicomyces brachiatus Santam. sp. nov.
MB#840606
Fig. 81
Diagnosis
Similar to M. homalotae, but differing by the dark and constricted cell VI (Fig. 81B, *), the appendage ramified inwards, the long outer branch (i.e., primary appendage) dorsally darkened, each antheridium bearing four phialides and two apical secondary appendages (Fig. 81F, *).
Etymology
The species epithet means “having branches”, because the branched primary appendage and additional branches around.
Type material
Holotype DENMARK – Nordøstsjaelland (NEZ) • Klinten ved Selsø; 55°44.158′ N, 11°59.634′ E; PG88; on Atheta sodalis (Erichson, 1837) (Col. Staphylinidae Aleocharinae); 11 Mar. 2007; JP 521; JP det.; ZMUC C-F-123004.
Isotype DENMARK • same data as for holotype; ZMUC C-F-123005.
Paratypes DENMARK – Østjylland (EJ) • Vest for Ørnsø ved Silkeborg; 56°9.126′ N, 9°30.588′ E; NH32; on A. sodalis; 10 Nov. 2018; JP 1232; JP det.; ZMUC C-F-123759. – Nordøstsjaelland (NEZ) • Indelukket ved Frederiksborg Slot; 55°56.191′ N, 12°17.861′ E; UC30; on Ocyusa picina (Aubé, 1850) (Col. Staphylinidae Aleocharinae); 12 Apr. 2016; JP 6; JP det.; ZMUC C-F-122477, C-F-122478.
Description
Thallus amber-coloured, with foot and outer margin of primary appendage blackened. Basal cell of receptacle (I) obconical and geniculate above the foot, about 1.5 times as long as broad. Suprabasal cell of the receptacle (II) small, triangular to trapezoidal, broader than long. Cell III variably cylindrical, ± inflated on the inner side, darkened on the outer, supporting the primary appendage and additional branches from the inner side. Usually, each thallus includes two secondary receptacles arising from cell II, bearing respective perithecia and antheridia.
Primary appendage unbranched or, rarely, once ramified, darkened along the entire outer margin, paler distally; sometimes with corrugated margins (Fig. 81C, pa). When seen in detail, the dark pigmentation shows a delicate roughness (Fig. 81D). Inner branch from cell III pale and ± ramified, sometimes simple and dorsally brownish (Fig. 81C, arrow).
Antheridia consisting of four superposed tiers of paired cells. Each of the four cells of the 2 nd and 3 rd tiers bear one phialide. The “sperm cavity” is sealed by four triangular cells on one side (Fig. 81E, far focus) and four on the opposite (Fig. 81G, near focus). Outer margins not protruding. The 4 th tier bears two long and diverging secondary appendages.
Perithecial stalk cell (VI) about two times as long as broad, narrower and darkened in its lower half (Fig. 81B, *). Perithecia ovoid, symmetrical, with blunt and truncate apex. Perithecial basal cells (m, n, n’) and VII provided with “stigmata” (Fig. 81J). Trichogyne consisting of a rounded base bearing few diverging, short branches (Fig. 81I, tr). Ascospores with the longer basal cell ending in a conical apex, and the apical shorter cell bearing a rounded and slightly prominent end (Fig. 81H). The spore wall expands in an elliptical outline into what will become the foot of the thallus (Fig. 81H).
Length from foot to tip of perithecia 106–135 µm. Perithecium (including basal cells) 61–80 × 27–36 µm. Antheridium (including pedicellar cell, without secondary appendages) 47–56 × 15–20 µm. Length of primary appendage (when undamaged) from primary septum above cell III 87–148 µm. Ascospores length (including expanded sheath at basal area) 34–38 µm.
Thalli were found on various body parts of the hosts. The hosts were sifted from moldy leaf litter along tree trunks and stubs in a shady deciduous forest, from moist rush and moldy leaf litter and mosses in a sun-exposed swamp along a rivulet, and from moist leaf litter and mosses at the edge of a light-open alder swamp.
Remarks
This species belongs to the M. homalotae group, which also includes M. britannicus, M. drusillae and M. validus sp. nov. It can be separated from the latter by a set of characteristics, such as the dark primary appendage, a constricted and darkened cell VI, four phialides per antheridium, and two secondary divergent appendages on antheridia.
description: Published as part of Santamaria, Sergi & Pedersen, Jan, 2021, Laboulbeniomycetes (Fungi, Ascomycota) of Denmark, pp. 1-425 in European Journal of Taxonomy 781 on pages 331-333, DOI: 10.5852/ejt.2021.781.1583, http://zenodo.org/record/5828924