Diastoma melanioides, (REEVE, 1849)

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 : 595-596

DIASTOMA MELANIOIDES (REEVE, 1849)

Material examined

Indian Ocean: Australia: WA: Esperance Bay, Taylor St Groyne ( USNM 801614).

Description

Marginal fold S-shaped ( Fig. 6B ), terminating at posterior tip of sorting area; oesophageal aperture at tip of marginal fold recurved segment; sorting area curving, tapering posteriorly to pointed tip; left margin of sorting area with conspicuous bulge; sorting area pad, anterior flap, crescentic pads, and accessory marginal fold lacking; glandular pad rounded, rectangular, extending far posterior to gastric shield, with large flap just behind gastric shield; pad supported by narrow, curving stalk representing reduced crescentic ridge; single digestive gland duct opening at left of glandular pad; accessory pads, caecum, and caecal folds lacking; U-shaped fold present below style sac aperture; typhlosoles unfused.

Remarks

Previously described by Houbrick (1981b: fig. 5G), showing the rectangular glandular pad, and tall, complex sorting leaflets of the sorting area, but incorrectly indicating the presence of two digestive gland ducts at the base of the major typhlosole. Similar to his description of the midgut of Campanile ( Houbrick, 1981a, 1989), Houbrick (1981b) interpreted the region of the stomach posterior to the gastric shield as the remnant of the spiral caecum, and referred to the glandular pad as a ‘fold emerging from spiral caecum’.

Figures

Figure 6. Midgut anatomy of Dialidae (A) and Diastomatidae (B). A, Diala sulcifera scobina (USNM 1083788). Scale bar: 0.5 mm. B, Diastoma melanioides (USNM 801614). Scale bar: 1.0 mm. Refer to the text for a list of anatomical abbreviations.