Difflugia elegans Penard, 1890
Diagnosis: Shell outline rough, pyriform usually with a constriction near the aperture to form a neck; an aboral tubular horn present, often curved and perforated at the apex; shell composed of small to large pieces of angular quartz and sometimes diatom frustules, bounded together by an organic cement; aperture usually circular, surrounded by an irregular mixture of particles which are collected to build a new shell; the apex of the test sometimes has two spines more or less symmetrically placed instead of a single spine. Nucleus spherical, with a number of nucleoli scattered throughout the nucleus; nucleoli with small lacunae.
Dimensions: Penard (1904): Length 80-100 µm. Length in literature 80-162 µm; width 39-99 µm. My measurements: Length 84-103 µm (n=49); nucleus 16.3-19.8 µm (n=2).
Remarks: Variation in the construction of the test is considerable, as is the length of the tubular horn, but the constriction behind the aperture distinguishes this species from D. bacillariarum which it closely resembles. Characteristic for this species is the almost always present bunch of mineral particles around the pseudostome.