Laboulbenia inexpectata Santam., 2021

Santamaria, Sergi & Pedersen, Jan, 2021, Laboulbeniomycetes (Fungi, Ascomycota) of Denmark, European Journal of Taxonomy 781, pp. 1-425 : 165-167

Laboulbenia inexpectata Santam. sp. nov.

MB#840602

Fig. 34

Diagnosis

Similar to L. argutoris Cépède & F.Picard , but differing by the base of outer appendage which consists of 2(–3) hyaline to pale cells contrasting with darkened cells above, and by the inner appendage structure.

Etymology

The species epithet means “unexpected”, because this species was unexpectedly found among many samples of beetles of the genus Acupalpus where other common species may be collected (e.g., L. inflata and L. stenolophi ).

Type material

Holotype DENMARK – Sydjylland (SJ) • Kongens Mose ; 55°0.745′ N, 8°56.557′ E; MF99; On Acupalpus exiguus Dejean, 1829 (Col. Carabidae ); 16 Apr. 2000; H. Liljehult 29; JP det.; ZMUC C-F-122502 .

Paratypes DENMARK • same data as for holotype; ZMUC C-F-122503 , C-F-122504 , C-F-122505 .

Description

Thallus brown, much darker or even blackened at preostiolar spots and foot; much paler, almost hyaline, at basal areas of appendage, ostiole, cell V and lower area of cell I. Basal cell of receptacle (I) obconical, 2–3 times as long as broad, slightly constricted at middle height, geniculate at base, almost hyaline except for the upper quarter which is variably brown as the remaining receptacle above. Suprabasal cell of receptacle (II) slightly longer than broad, gradually broadening from below upwards. Septum II–VI oblique. Cell III trapezoidal to rhomboidal, almost isodiametric. Cell V small, paler than its surroundings, 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. Insertion cell thick, deep dark brown.

Outer appendage unbranched, very long, three or more times as long as thallus length from foot to perithecial apex, consisting of 15 or more cells which are 2–4 times as long as broad each; apparently rigid (noticeable by needle manipulation when detaching the fungus from host cuticle), uniformly dark brown above second, or less common, third cell, the 2(–3) lower cells (i.e., basal and suprabasal cells) hyaline or pale brown, narrower than dark cells above ( Fig. 34E , *). Inner appendage short, hyaline to pale brown, consisting of a minute basal cell (about a quarter in length and half as broad than basal cell of outer appendage) ( Fig. 34C–D , bc ia) supporting 1(–2) elongated cells (about 2–3 times as long as broad), bearing three elongate, slightly brownish, flask-shaped antheridia ( Fig. 34C , an) forming a tripodlike structure ( Fig. 34D , an). Some additional cells under the antheridia were observed in a damaged or altered inner appendage. No sterile branches have been observed.

Perithecial stalk cell (VI) flattened, as broad but shorter than adjacent cell IV. Perithecium ovoidal, with convex margins, showing confluent black preostiolar spots which form a ring below the pale ostiole, that points outwards through a truncated tip.

Length from foot to apex of perithecium 151–161 µm. Perithecium (including basal cells) 74–82 × 28–35 µm. Length from foot to tip of outer appendage (when undamaged) 348–498 µm.

Thalli were found mostly on elytra and pronotum of the hosts. Four infected beetles were found in a sun-exposed heath bog.

Remarks

This probably rare species may be compared with several other species of the genus Laboulbenia showing an unbranched outer appendage, a reduced inner appendage (without sterile branches), and a mostly darkened receptacle including perithecium. All these features are shared by L. argutoris and perhaps L. benjaminii , from which the new species can be separated by the structure of the appendages, especially the outer appendage, with the two hyaline basal cells, contrasting to the rest of the dark appendage.

Figures

Fig. 34. Laboulbenia inexpectata Santam. sp. nov. A. Mature thallus. B. Paired mature and immature thalli. C–D. Inner appendage and lower part of outer appendage in detail, with labelled antheridia (an) and basal cell of inner appendage (bc ia). E. Lower cells of outer appendage in detail (*). Scale bars: A–B = 50 µm; C–E = 20 µm. Photographs from slides ZMUC C-F-122502 (holotype) (A–B), ZMUC C-F-122504 (C, E), ZMUC C-F-122503 (D).