Laboulbenia sphaerii Santam.

Santamaria, Sergi & Pedersen, Jan, 2021, Laboulbeniomycetes (Fungi, Ascomycota) of Denmark, European Journal of Taxonomy 781, pp. 1-425 : 202-204

Laboulbenia sphaerii Santam.

MB#239158

Fig. 43E–F

Nova Hedwigia 56(3): 414 ( Santamaria 1993a). –

Type: “ Spain. Barcelona: Mura , 31TDG11, spread over the entire body of Sphaerius acaroides Waltl ( Coleoptera Sphaeriidae ) captured on the soft mud of Mura river, S. Santamaria, BCB-Mycotheca SS·1047b [holotypus]”; BCB .

Diagnostic features

Thallus diminutive, up to 85 µm in total length. Receptacle four-celled, because cells III and IV remain undivided and form a single cell (III–IV) ( Fig. 43E–F ). Lower receptacle consisting only of cell I. Cell V oval or obtriangular, half of the length of cell III–IV, not connected with cell II. Outer appendage unbranched, with a hooked apex. Inner appendage consisting of 1–3 simple branches arising from a flattened basal cell and bearing some solitary antheridium. [Detailed descriptions: Santamaria 1998; Majewski 1999]

Distribution and hosts

Exclusively on the mud beetle Sphaerius acaroides (Col. Sphaeriusidae ) [= Microsporus acaroides (Waltl, 1838) , Col. Microsporidae ]. Reported from Spain (type), Poland ( Majewski 1999), and Sweden ( Huggert 2010, not named).

Collections examined from Denmark

On Sphaerius acaroides Waltl, 1838 (Col. Sphaeriusidae ) DENMARK – Nordøstsjaelland (NEZ) • Søndersø, Jonstrup Vang ; 55°46.278′ N, 12°22.010′ E; UB38; 1 Apr. 1872; leg. unknown Dry0028; det. unknown; ZMUC C-F-124098 .

Remarks

First record from Denmark. The Danish material consists of two immature thalli from a dry-preserved beetle captured in 1872 ( Fig. 43E ). Despite the scarcity and age of the material, the specimens are perfectly classifiable given the distinctive characteristics and ecology. For comparison and for documentary interest we reproduce a photograph of a mature thallus from the Spanish holotype ( Fig. 43F ).

Although most species in the genus Laboulbenia have a typically five-celled receptacle (namely cells from I to V), some species show undivided cells III+IV or III+IV+V. Song et al. (2019) listed 23 species with these characteristics but omitted L. sphaerii which is the only Danish species of the genus having undivided cells III+IV. These species have been reported to grow on hosts belonging to three insect orders ( Coleoptera, Diptera , and Heteroptera) and eight families ( Song et al. 2019); it will remain unknown whether this character evolved independently on multiple occasions until most of the species have been sequenced.

Figures

Fig. 43. Laboulbenia spp. A–B. L. rougetii Mont. & C.P.Robin. A. Mature thallus. B. Two young thalli showing antheridia (an). – C–D. L. slackensis Cépède & F.Picard. In D, the black and constricted septum separating the basal cell of outer appendage from outermost branch is labelled (arrow). – E–F. L. sphaerii Santam. E. A pair of two immature thalli. F. Mature thallus from holotype. Both images with undivided cells III and IV being labelled. Scale bars: 50 µm. Photographs from slides ZMUC C-F-124117 (A–B), ZMUC C-F-124219 (C), ZMUC C-F-122634 (D), ZMUC C-F-124098 (E), BCB SS1047b (holotype) (F).