Laboulbenia pygidicola Santam., 2021

Santamaria, Sergi & Pedersen, Jan, 2021, Laboulbeniomycetes (Fungi, Ascomycota) of Denmark, European Journal of Taxonomy 781, pp. 1-425 : 198-199

Laboulbenia pygidicola Santam. sp. nov.

MB#840605

Fig. 42

Diagnosis

Thallus slender. Outer appendage elongated and dark at least in the basal portion. Inner appendage consisting of 2(–3) branches borne directly on the basal cell. Each of these branches once divided above first cell in three-celled appendages, where each terminal cell is an elongated antheridium ( Fig. 42D–F , an). Perithecial apex obtuse, yet truncated, with a prominent dorsal lip.

Etymology

The species epithet refers to the “pygidium” (last abdominal segment of arthropods), where the fungus grows.

Type material

Holotype DENMARK – Nordvestsjaelland (NWZ) • Bognaes Skov på Tuse Naes ; 55°44.966′ N, 11°45.817′ E; PG78; on Syntomus truncatellus (Linnaeus, 1761) (Col. Carabidae ); 10 Dec. 2013; JP 886; JP det.; ZMUC C-F-123384 .

Paratype DENMARK – Sydsjaelland (SZ) • Østerskov ved Langebaek ; 54°59.235′ N, 12°6.280′ E; UA19; on S. truncatellus ; 14 Jan. 2012; JP 541; JP det.; ZMUC C-F-123025 .

Description

Thallus brown, especially darker at the appendages and perithecial apex, paler around the basal portions of the thallus and distal outer appendage. Basal cell of the receptacle (I) slender, narrowly elongated, up to five times as long as broad, with ± parallel margins, hyaline even in darker thalli. Suprabasal cell of the receptacle (II) shorter, darker and broader than cell I, somewhat gradually broadened towards the distal end, up to 3–4 times as long as broad. Cell III slightly longer than broad, almost rectangular in section. Cell IV shorter than III. Cell V very small, situated at the upper-inner corner of cell IV and separated from it by an oblique, curved septum that does not reach septum III–IV ( Fig. 42E ). Insertion cell brown but neither opaque nor deeply darkened or blackened, instead similar in colour to, or paler than its surroundings.

Outer appendage unbranched, consisting of up to 14 variably elongated cells, very long, as long as the length from foot to insertion cell; uniformly dark brown to gradually paler upwards. Inner appendage not exceeding the perithecial apex, consisting of a short basal cell about three times shorter than the outer but similar in width, giving rise to 2(–3) branches. Each of these branches includes a lowermost cell bearing two three-celled appendages, consisting of elongated and narrow cells where the terminal functions as an antheridium ( Fig. 42D–F , an).

Perithecial stalk cell (VI) rhomboidal, as long as broad, slightly shorter than adjacent cell III. Perithecium ovate-fusiform, broadest between tiers w 1 and w 2, gradually tapering into an indistinct neck and a truncate, flattened, slightly bent, darker apex, where preostiolar spots appear ± blurred.

Length from foot to apex of perithecium 194–302 µm. Perithecium (including basal cells) 95–120 × 24–34 µm. Length from foot to tip of outer appendage (when undamaged) 419–489 µm.

Thalli were found on the elytra of the hosts. The hosts were sifted from fresh flood debris on a coastal meadow and from old, mouldy and decomposed Phragmites piles on moist, sun-exposed ground.

Remarks

This species should be compared with L. metableti with which it coexists on the same host in the two samples studied. Both species may be distinguished by the cell arrangement of the inner appendage, by the elongation and slenderness of its receptacle and the outer appendage, and by the truncated perithecial apex of L. pygidicola sp. nov., among other characteristics. The status of this species could be compared with that of L. hyalopoda and L. notiophili . Laboulbenia notiophili and L. metableti have been found on many other parts of host bodies without undergoing important morphological changes, therefore L. hyalopoda and L. pygidicola sp. nov. seem to be good species instead of growth forms. Laboulbenia pygidicola sp. nov. seems extremely rare according to the large quantities of samples of infested Syntomus we have studied.

Figures

Fig. 42. Laboulbenia pygidicola Santam. sp. nov. B–C. Mature thalli. A, D–F. Inner appendage and surrounding areas in detail with labelled antheridia (an) and cell V. Scale bars: 50 µm. Photographs from slides ZMUC C-F-123384 (A–E) (holotype), ZMUC C-F-123025 (F).