Sphalloplana (Sphalloplana) virginiana Hyman 1945

Sphalloplana (Speophila) virginiana Hyman, 1945

Sphalloplana virginiana Hyman, 1945:477.

Sphalloplana (Sphalloplana) virginiana.—Carpenter, 1971:1284.

TYPE MATERIAL.—Holotype, whole mount of one specimen, AMNH 314. Paratypes, set of sagittal sections on 5 slides, MNH 315–319, and whole mount of three specimens on one slide, AMNH 706.

The following discussion is based on Hyman's (1945:477–478) description and a reexamination of Hyman's paratype sections.

EXTERNAL FEATURES.—A slender, white species, preserved specimens measuring to 12 mm in length.

ANATOMY.—The adhesive organ, according to Hyman, consists of an irregular depression lined with eosinophilic gland cells, from which a small band of retractor muscles proceed dorsally to join the dorsal subepidermal muscle layers. The paratype slide, however, shows a distinct invagination of the organ, as has already been noticed by Carpenter (1970:79).

In the reproductive system, the numerous testes are subventral, lying below the intestinal branches or extending into the mesenchymal spaces between the branches. Carpenter (1970:78) stated that the testes appeared to him to be dorsal rather than ventral on Hyman's slides; however, I see them there clearly in a ventral position.

The copulatory complex (Figure 53) is located at a considerable distance posterior to the pharyngeal pouch. The penis has a slightly developed bulb and a papilla (pp) of moderate size, somewhat more elongated than shown in Hyman's figure. The penial lumen lacks a distinct seminal vesicle and consists of a short, rather wide canal, the ejaculatory duct (de), which begins in the penis bulb, runs posteroventrally, and opens on the ventral side of the papilla close to its base. The two sperm ducts (vd) enter the penis bulb anteriorly and connect with the anterior end of the ejaculatory duct. The mouth of the common oviduct (odc) is on the posterodorsal roof of the male atrium (am). The rather small copulatory bursa (b) is situated above the penis bulb, with its outlet, the bursal duct (bd), running posteriorly and curving ventrally to connect with the common atrium (ac).

DISTRIBUTION AND ECOLOGY.—The type-locality of S. virginiana is Showalter's Cave in Rockbridge County, Virginia, where numerous specimens were collected in a pool on 30 October 1943 (Hyman, 1945:478). Carpenter (1970:80) visited this locality in 1969 and J. R. Holsinger at several occasions, both without finding any planarians.

TAXONOMIC POSITION.—Sphalloplana virginiana is here placed in the subgenus Speophila on account of its invaginated adhesive organ, as has already been suggested by Carpenter (1970:79). Its outstanding specific characteristics are the ventral position of the testes, the lack of a seminal vesicle, and, particularly, the ventral opening of the ejaculatory duct. The species appears to be rather close to S. subtilis (which, however, has a very weak adhesive organ) and to S. consimilis (which has the testes positioned dorsally). A closer comparison will be possible only after the reexamination of well-preserved specimens from the type-locality.