Difflugia hiraethogii Ogden, 1983
Diagnosis: The shell is light yellow or transparent, thin pyriform with a distinct neck or collar which often has parallel sides. The neck region is made of angular quartz and usually has a rough appearance, whilst the remainder of the body is composed of small to medium pieces of flattened quartz and has a smooth appearance. Organic cement is frequently seen in small areas as part of the shell matrix. It is in the form of a network, made of fused rings each having an internal diameter of about 250-320 nm and walls 200-260 nm thick. The aperture is circular and surrounded by assorted particles of quartz to give it an irregular outline. Some of the examined specimens had cyst plugs in their apertural openings. These plugs varied from being either an uneven mixture of angular quartz or flattish pieces, in both instances the sealing cement was similar to that binding the shell walls.
Dimensions: Based on twenty-six specimens: body length 137-171 µm, breadth 87-137 µm, depth 57-84 µm, diameter of aperture 35-52 µm; B/L 0.67 ± 0.06, d/L0.26 + 0.02.
Ecology: Sphagnum moss gathered at Myndd Hiraethog, Wales.
Remarks: Ogden (1983) notices “This species is similar to two other compressed species namely, D. compressa and D. lingula Penard, 1911. Complications regarding the species D. compressa Carter, 1864 should have been resolved by Cash & Hopkinson (1909) who suggested that from Carter’s figures he was ‘beyond question’ referring to a species of Pontigulasia. Nevertheless, the name has been used subsequently to refer to compressed specimens of Difflugia, either as D. compressa or D. oblonga/pyriformis var. compressa. Whether or not there are some genuine specimens of Difflugia amongst these descriptions is difficult to know, but the name compressa is preoccupied by Carter’s description and is no longer valid, and most refer to much longer, broader specimens than those described here. The present specimens are distinct from D. lingula Penard, 1911 and D. lingula var. regularis Gauthier-Lièvre & Thomas, 1958, because these have a more rounded shape which tapers sharply from the mid-body region to the aperture, and D. lingula also has an aboral horn. D. hiraethogii can be recognized by its lateral compression, distinct circular collar and aperture.”