Species: Tetraphalerella neglecta (James, 1881)
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Formerly: Strophomena neglecta
Formerly: Strophomena neglecta
- 1912 Strophomena neglecta Foerste, Bull. Sci. Lab. Denison Univ., 17, p. 90, pl. 5, figs 1 A-B; figs. 3 A-F; pl. 7, fig. 5; pl. 9, figs. 1 A-C; fig. 10; pl. 11, fig. 10.
Map point data provided by iDigBio.
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- C5 Sequence (Lower Whitewater, Waynesville)
Identification in Hand Sample
- Medium-sized, semicircular to semielliptical
- Lateral profile gently resupinate, with visceral disc gently and evenly convexo-concave, and geniculation at about 110°
- Hingeline straight, being widest part of shell; cardinal extremities extending into inconspicuous ears
- Ventral interarea apsacline; delthyrium and pseudodeltidium obscured by matrix
- Cardinal process lobes converging toward their bases, with each lobe bearing longitudinal depression on posterior surface of myophore
Tetraphalerella neglecta from Whitewater Formation of Camden, Ohio (OUIP 1351)
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Jin & Zhan (2001):
Jin & Zhan (2001):
- Description: (Southern Manitoba material) Shell usually medium-sized, semicircular to semielliptical, ranging from 17.7-26.4 mm in length and 25.7-37.9 mm in width, with an average length/width ratio of 0.7. Lateral profile gently resupinate, with visceral disc gently and evenly convexo-concave, and geniculation at about 110°. Hingeline straight, being widest part of shell; cardinal extremities extending into inconspicuous ears. Ventral interarea apsacline, attaining height of 1.4 mm; delthyrium and pseudodeltidium obscured by matrix. Dorsal interarea slightly lower than ventral interarea, anacline, attaining height of 1.2 mm; chilidium small, convex, covering posterior part of cardinal process. Entire shell covered by unequal, closely spaced parvicostellae (averaging 8 per 1 mm in medial part of shell); coarser costellae unevenly spaced, increasing anteriorly through intercalation. Concentric growth lines fine, evenly spaced over entire shell surface.
- Ventral interior: Not studied because of insufficient material.
- Dorsal interior: Cardinalia small, occupying about 6% of shell length and 21% of shell width; cardinal process lobes converging toward their bases, with each lobe bearing longitudinal depression on posterior surface of myophore. Socket ridges thin, plate-like, undercut anteriorly, continuous with base of cardinal process medially, etending antero-laterally and then postero-laterally toward hingeline, bounding shallow sockets. Muscle field shallow, subcircular in outline, occupying less than one-quarter of shell width and one-third shell length, divided by strong median ridge originating from low notothyrial platform; transmuscle septa lacking.
- Remarks: Compared to Tetraphalerella planodorsata (Winchell and Schuchert, 1892) from the Elgin Member of the Maquoketa Formation of Iowa (Wang, 1949) and the Surprise Creek Formation of Hudson Bay Lowlands (Jin et al., 1997), Tetraphalerella neglecta has a notably smaller shell with less sharp geniculation.
- Articulate brachiopod. Differs from similar species by its medium to large size, outline not strongly triangular, delicate striations, anterior margin not strongly thickened, muscle impressions inside pedicle valve fan-shaped with radial ridges, and absence of well defined sulcus and fold. Waynesville.
- (Note: on specimens from Texas) Shell very large for the genus; wider than long; outline subquadrate; anterior margin broadly rounded. Exterior surface unevenly costellate; finer costellae (commonly three) alternating with slightly coarser ones. Ventral valve moderately concave in lateral profile having maximum concavity just anterior to middle; posterior region flattened. Interarea long, plane, strongly apsacline; pseudodeltidium large, gently convex; palintrope supported by thick ridges. Teeth strong, dental plates flaring and merging with a high border surrounding the muscle field; exterior edge of border abruptly elevated. Muscle field large, transversely elliptical; adductors small, oval; diductors large, expanded anteromedianly to enclose the adductors completely, surface crenulated. Median ridge low, wide, and barely reaching the front margin of the muscle field. Surface outside of muscle field papillose; pallial channels moderately developed.
- A large, subquadrate, finely striated species with flabellate muscle area in the pedicle (ventral) valve. Width, 40-45 mm., length, 0.75 width. Hinge often extended. Shell thin, rather evenly concavo-convex. Muscle area of the pedicle valve large, circular to elliptical, diameter about 2/5 the width of the shell. Lateral border sharply elevated but impressed area rises gradually anteriorly.
- Restricted to the middle Blanchester. Along the eastern area of out-crop it is known as far south as Bath County. It is known in southern Indiana but has not been listed from the western area in Kentucky.
- Stophomena neglecta belongs to the S. incurvata type in which the muscle impression in the pedicle valve is rotund, with relatively low border, surface within the impression being marked radially by flabellate lines. Thickening along the margin of this valve relatively inconspicuous. Compared with S. planumbona, the shell is much larger and surface striae even finer. Anterior outline broadly rounded, posterior part as a rule somewhat prolonged at the hinge-line. Downward curvature of anterior part of brachial (dorsal) valve in some places considerable, but never as in typical S. hecuba.
- Locality and Horizon. Blanchester division of the Waynesville, southwestern Ohio; southeastern Indiana; Lewis, Fleming, and Bath counties, Kentucky. Similar specimens occur in the Richmond formation at Stonington, Michigan, and on Manitoulin island, a typical specimen was found immediately south of Kagawong, the only specimen known from Canada.