Sphalloplana (Speophila) buchanani Hyman 1937

Sphalloplana (Speophila) buchanani (Hyman, 1937)

Sphalloplana percoeca.—Beauchamp, 1931:321 [in part].

Speophila buchanani [nomen nudum] Hyman, 1936:129.

Speophila buchanani Hyman, 1937:468.

Sphalloplana buchanani.—Mitchell, 1968:615.

Sphalloplana (Speophila) pricei.—Carpenter, 1971:1283 [in part].

TYPE MATERIAL.—Syntypes, 6 specimens (2 whole mounts on one slide and 4 sets of serial sections on 11 slides), AMNH 648.

I had no opportunity of examining living specimens of this species, only Hyman's type slides that are histologically very poor, in part with badly faded stain. Sphalloplana buchanani was described originally by Hyman (1937:468–469) from preserved specimens obtained by Prof. J. W. Buchanan in Mammoth Cave in Kentucky. Carpenter (1970, 1971) considers the species to be identical with S. pricei from Pennsylvania. In the absence of an exact analysis of its anatomy, however, we may consider this identity to be still an open question. The following account is based chiefly on the literature data available.

EXTERNAL FEATURES (Figure 15).—Hyman (1937, fig. 16) published an illustration of the aspect of the species in life, prepared by Buchanan. It varies in length from 7 to 15 mm. The anterior end is shown to be truncate with rounded lateral edges, lacking auricular projections. The protrusible adhesive organ appears as a retracted conical structure. The intestinal area terminates anteriorly with a V-shaped outline. The pharynx, measuring about one-eighth of the body length, is inserted somewhat posterior to the middle of the body, and the copulatory complex occupies the anterior third of the postpharyngeal region. All these features are compatible with the conditions obtaining in S. pricei.

ANATOMY.—The deeply invaginated adhesive organ and the lateral marginal zone with large rhabdites are developed typically. The testes, in moderate number, are prepharyngeal and dorsal (in S. pricei they are dorsal, ventral, and intermediate). Illustrations of the copulatory organs (Figure 56) have been given by Hyman (1937, fig. 19) and probably by Beauchamp (1931, fig. 6), who confused the species with the sympatric S. percoeca. Both figures show the aspect of the organs in dorsal view; however, Hyman's slide of horizontal sections, from which her figure is drawn, shows the bursal duct to be on the right side of the penis rather than on the left side. The penis has a rather muscular bulb (pb) and a cylindrical to conical papilla (pp). The vasa deferentia enter the bulb laterally, traverse its tissues, and unite to a rather narrow canal, the ejaculatory duct (pl), which runs through the center of the papilla and opens at its tip. There is no seminal vesicle developed, but in Hyman's figure a widening of the ejaculatory duct is shown near the tip of the papilla. Carpenter (1970:92) also stated that in his specimen of “S. pricei” from Mammoth Cave no dilated seminal vesicle was present. The common oviduct (odc) opens into the male atrium close to the entrance of the bursal stalk (bd), which is there enlarged to form a vagina (v) with somewhat muscular walls.

DISTRIBUTION AND ECOLOGY.—The only reliably documented habitat of S. buchanani is Mammoth Cave, Edmonson County, Kentucky, where it was collected first in 1928 (Bolivar and Jeannel, 1931: 38, in Audubon Avenue, together with S. percoeca), by Buchanan and others in October and November 1935 (in the less accessible and deeper parts of the cave, Hovey's Cathedral Domes, Fox's Alley, and Becky's Alley, see Hyman, 1937:469), and again by Carpenter (1970:92, 180).

Additional localities recorded in the literature need further confirmation. McRitchie (1959:24) reported “Speophila buchanani” from Mill Creek Cave, Davidson County, Tennessee. Carpenter (1970:92) found a Sphalloplana which he believed to be identical with the Mammoth Cave form in Cathedral Cave, Edmonson County, Kentucky, a few miles from Mammoth Cave. His specimens, however, had a well-developed seminal vesicle and the vasa deferentia entering the penis bulb posterodorsally (see his fig. 51). Finally, Barr and Kuehne (1971:70) observed S. buchanani in a stream in Great Onyx Cave, Edmonson County, Kentucky, a locality where Carpenter (1970:180) had collected only S. percoeca.

A few physicochemical parameters of the habitat of S. buchanani are given by Hyman (1937:469). The temperature of the water in Mammoth cave was 55°F [12.8°C], the pH, 7.6. Barr (1968:155) observed the species in temporary drip pools and assumes that it survives the periods of dryness by encystment in the hygroscopic deposits at the bottom of the pools, as does S. percoeca.

TAXONOMIC POSITION.—Sphalloplana buchanani appears to be very close to S. pricei, from which it differs by the location of the testes and the anatomy of the penis, particularly the absence of a seminal vesicle and the morphology of the ejaculatory duct.