Fossarus ambiguus, (LINNE, 1758)

Strong, Ellen E., 2011, More than a gut feeling: utility of midgut anatomy in phylogeny of the Cerithioidea (Mollusca: Caenogastropoda), Zoological Journal of the Linnean Society 162 (3), pp. 585-630 : 598

FOSSARUS AMBIGUUS (LINNÉ, 1758)

Material examined

Atlantic Ocean: Mediterranean Sea: France: Corsica, Calvi ( USNM 857631).

Description

Marginal fold S-shaped ( Fig. 9A ), terminating at posterior tip of sorting area; oesophageal aperture at apex of marginal fold recurved segment; sorting area triangular, with pointed posterior tip; left margin of sorting area straight; accessory marginal fold curving around posterior tip of sorting area; sorting area pad, anterior flap, and crescentic pads lacking; glandular pad forming small, rounded mound projecting short distance posteriorly behind gastric shield; single digestive gland duct opening at left of glandular pad; crescentic ridge forming small diverticulum from posterior end of glandular pad with proximal tip well posterior to digestive gland duct; accessory pads, caecum, and caecal folds lacking; U-shaped fold present below style sac aperture; typhlosoles unfused.

Remarks

Described by Houbrick (1990b: 69) simply as possessing a style sac, prominent gastric shield, large central ridge, a sorting area, and a single digestive gland duct.

Figures

Figure 9. Midgut anatomy of Planaxidae. A, Fossarus ambiguus (USNM 857631). Scale bar: 0.5 mm. B, Planaxis sulcatus (USNM 1083482). Scale bar: 1.0 mm. Refer to the text for a list of anatomical abbreviations.