Terebralia semistriata, (MORCH, 1852)

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 : 601

TEREBRALIA SEMISTRIATA (MÖRCH, 1852)

Material examined

South Pacific Ocean : Australia: QLD: Cockle Bay, Magnetic Island, 19°08.0′S, 146°50.0′E ( USNM 828806 ); Cairns: Airport Mangrove Boardwalk, 16°53.0′S, 145°45.7′E ( USNM 1083479 ) .

Description

Marginal fold S-shaped ( Fig. 10C ), terminating at posterior tip of sorting area; oesophageal aperture at tip of marginal fold recurved segment; sorting area rectangular, with broadly rounded posterior margin; anterior sorting area modified into prominent concave flap; left margin of sorting area with slight bulge posteriorly bordering flap; accessory marginal fold straight along sorting area left margin, extending far posteriorly into gastric chamber along left side of roof; sorting area pad and crescentic pads lacking; glandular pad large, elongate, flattened with narrow stalk, extending far posterior to gastric shield; paired digestive gland ducts opening at left of glandular pad; crescentic ridge long, extending from oesophageal aperture, past digestive gland ducts, curving around posterior end of glandular pad, fusing to side of pad slightly behind gastric shield, with distal tip curving slightly into caecum; shallow caecum present opposite three caecal folds; small accessory pad present (not visible) at anterior end of glandular pad, opposite major typhlosole; U-shaped fold present below style sac aperture; style sac extremely long, extending into mantle roof; typhlosoles fused along entire length.

Remarks

The present description agrees closely with that of Terebralia sulcata ( Houbrick, 1991b: fig. 17), although Houbrick (1991b) noted the presence of only a single duct of the digestive gland, the caecal folds were overlooked, and the ventral floor of the gastric chamber to the right of the glandular pad was interpreted as a sorting area.

Figures

Figure 10. Midgut anatomy of Potamididae. A, Cerithidea scalariformis (USNM 1143351). B, Telescopium telescopium (USNM 828804). C, Terebralia semistriata (USNM 1083479). Note that a small accessory pad is present, but is not visible in this view. D, Tympanotonus fuscatus (USNM 858078). Scale bars: 1.0 mm; refer to the text for a list of anatomical abbreviations.