Sternodromia spinirostris (Miers, 1881)

Guinot, Danièle & Quenette, Gwenaël, 2005, The spermatheca in podotreme crabs (Crustacea, Decapoda, Brachyura, Podotremata) and its phylogenetic implications, Zoosystema 27 (2), pp. 267-342 : 294-296

Sternodromia spinirostris (Miers, 1881)

Female 45 × 53 mm, Ivory coast, Guinean Trawling Survey (MNHN-B 24117); female 58 × 69 mm, Congo, off Pointe-Noire (MNHN- B 7862); female 40 × 41 mm, Gulf of Guinea (MNHN-B 22052).

The thoracic sternum ( Fig. 15 ) is rather narrow; sternite 4 forms an elongated plate, with external borders parallel and anterior margin truncated, in contact with the mxp3 coxae. The female sternal sutures 7/8 gradually converge anteriorly and end at the level of P2. Their subterminal part forms a very narrow and long slit; these slits taper near their extremity where there is only a tiny terminal perforation ( Fig. 15B ). A marked tubercle surrounds the extremity of sutures 7/8; internally, it corresponds to a marked hollow. The bottom of the slit that is not externally closed and corresponds to a slight separation of the two sheets of the phragma 7/8, may serve as aperture of the spermatheca, since we have seen several individuals with sperm inside and around it. Sperm can therefore penetrate in the underlying channel that corresponds to the open part of endosternite 7/8. In a female (MNHN-B 22052) a hardened brown (partly yellowish) sperm plug was seen glued to the sternum, surrounding the half terminal part of the sutures 7/8 and including these slits ( Fig. 15A ). In another female (MNHN-B 7862), small fragments of male seminal material protruding from the slits were observed.

The bulb of the spermatheca is well defined and globular (and may be extremely salient in some other individuals), not tapering; anteriorly, a small prominence is well visible. The chamber is well dilated, filled by sperm; inner wall is soft, markedly ornamented; the outer wall is more calcified. There is no distinct basal thickening. The tube is thick but becomes flatter at the level of the subterminal slit, which connects the underlying spermathecal channel and the exterior.

Figures

FIG. 15. — Sternodromia spinirostris (Miers, 1881); A, female 40 × 41 mm, Gulf of Guinea (MNHN-B 22052), thoracic sternum showing sperm plug around slits of the spermathecae; B, female 34 × 37.2 mm, Gulf of Guinea (MNHN), detailed view of anterior sternal plate. Abbreviations: a, spermathecal aperture; cx1, cx5, P1, P5 coxae; e5, episternite 5; g, female gonopore; sl, slit; s.p., sperm plug; t, tubercle; 4-8, sternites 4-8; 5/6-7/8, thoracic sternal sutures 5/6 to 7/8. Scale bar: A, 2.5 mm.