Claparedellus lachmannii Khanipour Roshan and Clauß, 2021
Improved diagnosis (Siemensma and Holzmann, 2023): Stationary cells spherical, locomotive cells ovoid to elongate pyriform or irregularly shaped, with a hyaline, flexible, membranous wall, varying in thickness. Peduncle circular in cross-section, relatively narrow. Nuclei spherical, ovular. Cytoplasm without crystals. Stationary cells can stay for several days under an accumulated layer of waste material and debris that serves as protective cover.
Description. The tests are spherical to ovoid or irregularly shaped, in fast locomotion elongated pyriform, free of agglutinated materials, with a rounded or conical proximal end, with a flexible, hyaline wall, variable in thickness (0.5-8.0 µm). The length of the test is 72-320 µm, with one terminal oblique aperture. Cells are multinucleate, with about 100 nuclei, 6.5-12.7 µm in diameter, with a singular hemispherical eccentric nucleolus lying close to the nuclear membrane. The test is colorless, cells may appear yellowish or brown due to ingested food particles. Almost all tests show bilateral symmetry. The cytoplasm is granular without any crystals, but with several food and some contractile vacuoles. The peduncle is more or less circular in cross section and relatively narrow, and surrounded by a hyaline sheath. Locomotive cells move slowly along a long and relatively thick extended pseudopodium, with several trailing pseudopodia.
Remarks: This species is morphologically almost identical with L. wageneri and L. paludosa, but differs in its habitat (soil and dry mosses vs. freshwater). It differs from L. paludosa also in the structure of the nuclei (one large peripheral nucleolus vs. several small nucleoli scattered throughout the nucleus), their number (≥ 100 vs. 1-30) and size (6.5-12.7 µm vs. 20-82 µm; reference for L. paludosa). It differs from Edaphoallogromia australica mainly in the size of the nuclei (6.5-12.7 µm vs. 3.5-6.8 µm) and the structure (one large peripheral nucleolus vs. several small nucleoli scattered throughout the nucleus; see above and Meisterfeld et al. 2001).
Habitat: Feeds on filamentous Klebsormidium, coccale algae, cyanobacteria, diatoms, rotifers and yeast. The holotype was isolated from biocrust in sand dunes along the shore of the Baltic Sea; northern Germany (N 54°09’10.7″N 11°41’25.9″E), June 2017. A second strain of C. lachmannii was found in Jüterbog, Germany, and cultured from dry moss growing on a tree (51°59’43.45″N 13°4’21.17″E), April 2018. In July and September 2021, one specimen each of Claparedellus lachmannii was isolated from material aspirated with a wide mouth pipette between submerged basalt blocks along the shore of Gooimeer, a large freshwater lake in the central area of the Netherlands, at a depth of about 25 cm. In sampling material from the same site two more specimens were collected in January 2023. In June 2022, another C. lachmannii specimen was isolated from sediment collected in a dune lake near the village of Castricum, the Netherlands.
The occurrence of C. lachmannii in four different ecological niches is a remarkable fact. The species was isolated from biocrust samples of sand dunes along the shore of the Baltic Sea and dry moss growing on a tree (Siemensma et al., 2021), further specimens were sampled from a shallow oligotrophic freshwater dune lake and in the swash zone between basalt blocks of a eutrophic lake (this study). It is not possible to label C. lachmannii as either a soil or freshwater species, nor can the species be connected to a certain habitat.
References:
Siemensma and Holzmann, (2023). Novel contributions to the molecular and morphological diversity of freshwater monothalamid foraminifera: Description of six new species. Europ. J. Protozool.
