OBSERVATIONS ON THE FORMATION OF SPERMA- TOPHORES IN A BULIMULID LAND SNAIL, DRYMAEUS CANALICULATUS (PFEIFFER, 1845) (MOLLUSCA, GASTROPODA, PULMONATA)

by ABRAHAM S. H. BREURE and ALPHONS A. C. ESKENS (Department of Systematicsand EvolutionaryBiology, Rijksmuseum van Natuurlijke Historie, Leiden, The Netherlands)

SUMMARY

In one specimen of Drymaeus canaliculatus (PFEIFFER,1845) a spermatophore was observed in the phallus complex. The structure of the spermatophore is described using light microscopy observations and histological methods. A hypothesis is presented describing the formation of spermatophores in the epiphallus and flagellum The process of spermatophore-formation is initiated in the most distal part of the epiphallus and the proximal part of the flagellum.

INTRODUCTION

During dissections spermatophores are quite often observed in the spermathecal duct, but the presence of a spermatophore in the phallus complex is highly exceptional. This fact probably accounts for our poor knowledge of the process of spermatophore-formation. Data relating to this subject are given in FRETTER & GRAHAM (1964), GRASSE (1968), RUNHAM & HUNTER (1970) and SMITH (1966). These data may be summarized as: "the epiphallus participates with the flagellum to form spermatophores" (HYMAN, 1967: 595). No details are known of the actual process.

MATERIAL AND METHODS S

The material studied by us was collected by Dr. W. Weyrauch at Oxapampa, Department Pasco, Peru. The two specimens (Sencken- berg Natur-Museum, Frankfurt a/M) were most probably fixed in alcohol 70%, which as a rule does not make the material particularly suitable for histological studies. After embedding in paraffin, the material was sectioned at 7 ym and stained with (1) Alcian Blue after kalium permanganate oxidation, followed by Haemalum and Phloxine, or (2) Haemalum and Eosin in alcohol 80%. The slides were mounted 272

in malinol and have been deposited in the Rijksmuseum van Natuur- lijke Historie, Leiden (slides H 3963-3981).

RESULTS

Genitalia.-The penis has a proximal sheath, which begins slightly above the base of the penis and which is ca. 1 /6 the length of the phallus complex. The penis and epiphallus are more or less sub- cylindrical and there is hardly any external differentiation between these two parts; only the distal part of the penis is weakly indicated by an external swelling. The most distal part of the epiphallus is also somewhat swollen externally. The flagellum is rather slender and relatively short. The short retractor muscle is terminally attached (Figs 1-2). In transverse sections of the flagellum a curved longitudinal fold is

Figs 1-2. Drymaeu,rcanalilculatus (Pfeiffer). Peru, Dept. Pasco, Oxapampa. 1, phallus complex. EP, epiphallus; FL, flagellum; P, penis; PS, penis sheath; VD, vas deferens; d, distal; p, proximal. 2a, inner structure of phallus complex. 2b, detail of flagellum and distal part of epiphallus. A.E. del.