Habitus: Live animals have an external appearance which is characteristic for several Mediterranean and Atlantic species of Procerodes: body margins more or less parallel, rounded hind end, and the front end with a pair of auricles. From the sagittal sections it was determined that the preserved specimens varied from 0.375-0.8 mm in length. According to a note on the sketches of Dr. Sopott-Ehlers, living animals are about 1.5 mm long. From transverse sections it was determined that the width of preserved specimens is about 0.4 mm.
Although no information on colouration was given by the collector, the animals probably are devoid of pigment since no pigment granules appeared to be present underneath the epidermis. The eyes are set rather wide apart.
The anterior ramus of the intestine extends anterior to the eyes and gives off a pair of branched preocellar diverticula. Behind the brain the anterior ramus gives rise to about six pairs of branched lateral diverticula. Each posterior intestinal ramus gives off about 9-10 branched diverticula.
The inner circular muscle layer of the pharynx is considerably thicker than the outer one. The mouth opening is situated at the hind end of the pharyngeal cavity.
Male Reproductive System
There are about 8 pairs of testes, extending from a short distance behind the brain up to the level of the copulatory bursa. The relatively large follicles are situated dorsally between the tips of the intestinal diverticula.
At about the hind end of the pharyngeal pocket the vasa deferentia enlarge to form large false seminal vesicles. Behind the pharyngeal pocket the vasa deferentia curve medially and decrease in diameter. At the base of the penis papilla the ducts fuse to a broad ejaculatory duct which, almost without decreasing in width, opens at the tip of the penis papilla.
The papilla is a barrel-shaped structure with an extremely blunt tip. An orange staining secretion dominates in the penis papilla and is also present dorso-laterally of the penis bulb. A number of oval-shaped glandular elements are also present in the papilla. The gland cells are filled with the orange, granular secretion which was already mentioned above. These gland cells were already observed by Dr. Sopott-Ehlers in the living specimens.
Female Reproductive System
Ovaries were absent in the specimens examined.
The female copulatory apparatus consists of a copulatory bursa, bursal canal, and the diverticulum of the latter. The rounded bursa lies behind the penis and is lined with tall, vacuolated cells with nuclei at their bases. From the bursa arises a nucleate bursal canal, which opens ventrally to the exterior and also communicates with the male atrium. The diverticulum arises from the proximal portion of the muscular, bursal canal and receives the secretion of shell glands. It could not be determined unequivocally whether the oviducts open separately into the diverticulum or by means of a common oviduct.
The number of retinal cells could not be determined; there is no lens to the eyes.
The specimens were collected from an interstitial habitat.
Southern part of the river Tagus, Portugal.
Private collection B. Sopott-Ehlers: Serial sections on 5 slides, as follows: 4 slides with sagittal sections of 4 immature specimens and 1 slide with transverse sections of a sexually mature animal, coll. 30.10.1972.
Dr. Sopott-Ehlers, who collected the animals, studied the living and preserved specimens, of which she made drawings and photographs that were of a great help in the description.