Bittiolum varium, (PFEIFFER, 1840)

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 : 592

BITTIOLUM VARIUM (PFEIFFER, 1840)

Material examined

Atlantic Ocean: US: Florida: Indian River Lagoon, Fort Pierce Inlet , North Causeway , 27°28.20′N, 80°19.04′W ( USNM 1143345 ) .

Description

Marginal fold S-shaped ( Fig. 4B ), curving well past posterior end of sorting area; oesophageal aperture at apex of marginal fold recurved segment; sorting area curving, tapering posteriorly to pointed tip; left margin of sorting area with slight bulge; sorting area pad, anterior flap, crescentic pads, and accessory marginal fold 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 just behind digestive gland duct; accessory pads, caecum, and caecal folds lacking; U-shaped fold present below style sac aperture; typhlosoles unfused.

Remarks

Previously described by Marcus & Marcus (1963: fig. 83) and Simone (2001: figs 340, 341), showing the small glandular pad. Marcus & Marcus (1963) rather accurately depict the tapering sorting area, but indicate that the extension of the marginal fold terminates ventrally within a small, glandular pocket behind the gastric shield, which is identified as the vestige of the spiral caecum ( Fretter & Graham, 1962). Simone (2001) correctly illustrates the crescentic ridge, but interpreted the coarse, cuticularized folds at the anterior gastric chamber roof as part of the sorting area.

Figures

Figure 4. Midgut anatomy of Cerithiidae. A, Cerithidium fuscum (USNM 1084217). Scale bar: 0.5 mm. B, Bittiolum varium (USNM 1143345). Scale bar: 0.5 mm. C, Bittium reticulatum (USNM 858185). Scale bar: 0.5 mm. D, Cacozeliana granaria (USNM 1083787). Scale bar: 1 mm. E, Ittibittium parcum (USNM 857100). Scale bar: 0.5 mm. Refer to the text for a list of anatomical abbreviations.