Bdelloura wheeleri

Wilhelmi, 1909

Overview
Diagnosis: Bdelloura wheeleri Wilhelmi, 1909 is characterized by its highly muscularized, stubby penis papilla with its peculiar tip.
Habitus: The whole mount examined was about 9 mm long and 4.75 mm wide. The body is broadly lanceolate; the hind end shows a broad adhesive disk that is set off from the rest of the body by a shallow constriction at the lateral margins. The two eyes are situated close to the mid-line of the body. Pigment is absent. The distance from the posterior margin to the gonopore is about 2.1 mm and the distance from the latter to the mouth opening about 1.65 mm.

Alimentary System
The anterior ramus of the intestine terminates at a short distance behind the brain. The posterior rami do not fuse to a single branch, as in Syncoelidium pellucidum, but it could not be determined whether there are any connections between the gut branches.
The pharynx is about one-fourth of the body length; the inner circular muscle layer is much thicker than the outer one. The mouth opening is very large (about 620 µm in diameter) and is situated at the middle of the pharyngeal pocket.

Male Reproductive System
The testes occur dorsally as well as ventrally, extending well between the intestinal branches; the follicles extend from the level of the ovaries to well behind the copulatory apparatus. There are about 200 testes on either side of the body.
The vasa deferentia form large false seminal vesicles already anterior to the pharynx. At the hind end of the pharyngeal cavity the ducts narrow again, then turn mediad, shortly after which they make a laterally directed bend. Hereafter, each vas deferens increases in diameter and forms a seminal vesicle which turns medially towards the penis bulb. The last-mentioned vesicle narrows considerably over a short distance and then penetrates the lateral surface of the penis bulb. Shortly after having entered the bulb, the vasa deferentia enlarge again to form another seminal vesicle; the ducts only unite just before the tip of the intrapenial papilla to form an extremely short common vas deferens.
The intrapenial papilla is well developed and shows a more or less horizontal or a somewhat oblique orientation; it is situated in the spacious ejaculatory duct.
The penis papilla is a broad stubby structure. The tip of the penis is set off from the rest of the papilla by a pronounced constriction. The opening of the ejaculatory duct at the tip must be tiny since it could not be discerned in the sections examined.
The lining epithelia of the ejaculatory duct and the intrapenial papilla are penetrated by the numerous openings of penis glands.
The musculature of the penis bulb is well developed. The circular muscle layer of the penis papilla is highly developed and is overlain with a much thinner layer of longitudinal muscles. Both muscle layers are continuous with those surrounding the common atrium and continue, albeit greatly reduced in diameter, on the small projection that forms the tip of the penis papilla. Musculature could not be discerned on either the intrapenial papilla or around the ejaculatory duct. A thin layer of circular muscles surrounds the common vas deferens.
The atrium is surrounded with a well developed outer layer of circular muscles and a somewhat thinner inner zone of longitudinal muscle fibres.

Female Reproductive System
The small ovaries lie medially to the ventral nerve cords and at a considerable distance behind the brain, i.e. between one-fourth and one-third of the distance between the brain and the root of the pharynx. The oviducts arise from the postero-lateral surface of the ovaries and follow the course of the ventral nerve cords. At the level of the gonopore each oviduct gives off a short lateral branch which meets the stalk of the lateral bursa. Hereafter, the oviducts continue their course and unite to a common oviduct, which opens into the female genital duct. The latter distinguishes itself from the common oviduct in that its wall is more developed and its lumen wider. Where the female genital duct communicates with the rather spacious female atrium, its lining passes into a layer of tall cells which lines the atrium. Extensive shell glands discharge their secretion into the female genital duct. Oviducts, common oviduct and female genital duct are surrounded by a layer of circular muscles.
A large lateral bursa is situated on either side of the copulatory apparatus. Each bursa consists of a sac-shaped vesicle and a stalk. The lateral bursae open ventrally to the exterior via a separate pores which lies laterally to the ventral nerve cords. The stalks are ciliated and provided with well developed layers of circular and longitudinal muscles. Each stalk receives at its medial wall the opening of the short branch from the oviducts. The sac-shaped vesicles of the lateral bursae are lined with tall cells.
The vitellaria are numerous and well developed, filling most of the space between the intestinal diverticula. The bulk of the vitellaria is situated medially to the testes.

Eyes
Each pigment cup contains two retinal cells; there is no lens to the eyes.

Reproduction
Life Cycle: The animal of whole mount NC-3 had an oval-shaped cocoon in its atrium, measuring about 2.5 mm in length and 2 mm in diameter. According to Wilhelmi (1909) cocoons are 1.75-2.25 mm long and 1.25-1.75 mm wide, with a pedicel of about 0.4 mm long.

Ecology
The animals examined were collected from Horseshoe Crabs in a laboratory culture at the University of Waterloo, Ontario, Canada; the Crabs had been obtained from North Carolina. Further, the species has been collected from Woods Hole, Mass., U.S.A. (Wilhelmi 1909).
According to Wilhelmi (1909) the cocoons are mostly deposited at the basal part of the gill leafs.

Distribution
The animals examined were collected from Horseshoe Crabs in a laboratory culture at the University of Waterloo, Ontario, Canada; the Crabs had been obtained from North Carolina. Further, the species has been collected from Woods Hole, Mass., U.S.A. (Wilhelmi 1909).

Material Examined
Private collection I. R. Ball: NC-1, ex King Crab, North Carolina, 2.05.1972, sagittal sections on 9 slides; NC-2, sagittal sections on 7 slides; NC-3, whole mount on 1 slide.