Cymatorhynchia quadriplicata ( Zieten, 1830 )

Feldman, Howard R., Schemm-Gregory, Mena, Ahmad, Fayez & Wilson, Mark A., 2012, Jurassic rhynchonellide brachiopods from the Jordan Valley, Acta Palaeontologica Polonica 57 (1), pp. 191-204 : 196-197

Cymatorhynchia quadriplicata ( Zieten, 1830)

Figs. 3B, 4 .

1830 Terebratula quadriplicata ; Zieten 1830: 55, pl. 41: 3.

1851 Terebratula quadriplicata ; Quenstedt 1851: 453, pl. 36: 16; 1858: 423, pl. 58: 5–8; 1868–1871, pl. 38: 42.

1851–1852 Rhynchonella quadriplicata (Zieten) ; Davidson 1851 –1852: appendix: 23, pl. A: 22; 201, pl. 29: 1–3.

1918 Cymatorhynchia quadriplicata (Zieten) ; Buckman 1918: 53–54.

1918 Rhynchonella quadriplicata (Zieten) ; Rollier 1918: 148.

1936 Rhynchonella quadriplicata (Zieten) ; Arcelin and Roche 1936: 59, pl. 2: 1–6, pl. 11: 1, 4, 5, pl. 12: 5, pl. 13: 3, 4.

1939 Rhynchonella quadriplicata (Zieten) ; Roche 1939: 268, pl. 4: 11.

1965 Cymatorhynchia quadriplicata (Zieten in Davidson); Rousselle 1965: 52, pl. 2: 11, 12.

1966 Cymatorhynchia quadriplicata (Zieten) ; Alméras 1966: 70–97, 73, pl. F–G, pl. 2: 5–8.

1966 Cymatorhynchia quadriplicata var. vergissonensis ; Alméras 1966: 79, pl. D–E, pl. 2: 1–4.

1966 Cymatorhynchia quadriplicata var. lata ; Alméras 1966: 88, pl. I, pl. 4: 6–8.

1966 Cymatorhynchia quadriplicata var. depressa ; Alméras 1966: 95.

1966 Cymatorhynchia quadriplicata var. trilobata ; Alméras 1966: 96.

1969 Cymatorhynchia quadriplicata (Zieten) ; Pevny 1969: 143, pl. 28: 1a–c.

1980 Cymatorhynchia quadriplicata (Zieten) ; Fischer 1980: 140, pl. 58: 1, 2.

1981 Cymatorhynchia quadriplicata (Zieten) ; Parnes 1981: 21, pl. 2: 5–13.

1987 Cymatorhynchia quadriplicata (Zieten) ; Shi 1987: 55, pl. 3: 12.

1993 Cymatorhynchia quadriplicata ( Zieten, 1830) ; Shi and Grant 1993: 72–73, pl. 7: 17–19, pl. 8: 8–13, pl. 9: 1–7, 11–17, pl. 12: 1, 2, 6, 7.

1996 Cymatorhynchia quadriplicata ( Zieten, 1830) ; Alméras and Elmi 1996: pl. 1: 21.

Material.—42 articulated specimens: AMNH FI− 72369 (sectioned), AMNH FI− 72370, bed S−7, AMNH FI− 72371, AMNH FI− 72372, AMNH FI− 72373, AMNH FI− 72374, AMNH FI−72375, bed S−10, Mughanniyya Formation, Tel el Dhahab section; AMNH FI− 72376, bed 21a, AMNH FI− 72377, bed 21b, AMNH FI− 72378–79, bed 25, Hamam Formation, Arda section GSI M 2975, GSI M 742, GSI M 4510, GSI M 4522, GSI M 4539, GSI M 4553, GSI M 4556, GSI M 4565 (collected from the Tel el Dhahab section but beds not identified), Jordan. Description.—Shells medium to large ( Table 2), subpentagonal to subquadrate in outline, moderately dorsibiconvex, maximum width near midlength. Anterior commissure widely uniplicate. Ventral beak short, suberect to erect, deltidial plates disjunct to conjunct; costae subangular to sharp numbering about 16–17; growth lines barely visible near anterior commissure.

Ventral valve moderately to strongly convex posteriorly but less convex anteriorly; a broad, shallow sulcus originates just past one−third of valve length bearing 3–4 strong subangular costae, 5–6 costae on ventral flank; foramen round, small to medium sized, ventral interarea low.

Dorsal valve more globose posteriorly, flattened toward anterior commissure; moderately convex in lateral view; a broad, low fold originates just posterior to midlength bearing 4 costae with 6 costae on dorsal flank.

Interior. Very short, low dorsal median septum, strong dental plates parallel to subparallel anteriorly in one sectioned specimen, teeth short, somewhat bulbous; septalium not preserved, outer hinge plates subhorizontal arched slightly ventrally, sockets deep, asymmetrical, crura raduliform.

Discussion.—The shells differ from Cymatorhynchia? singularis ( USNM 303631) of Cooper (1989) in possessing less costae, a more inflated dorsal valve and less tumid ventral posterior. Buckman’s (1918: pl. 17: 15a, c) C. cymatophorina is wider and has finer and more numerous costae (about 26 on the dorsal valve). Cymatorhynchia quadriplicata var. inflata Alméras ( USNM 319165) has a more subcircular outline, more inflated dorsal valve, finer and denser ribs as well as a less developed fold and sulcus as noted by Shi and Grant (1993). They also noted that the Tethyan form varies considerably in morphology and was split into seven variants by Alméras (1966). Five of the variants (except for C. quadriplicata var. densecosta and C. quadriplicata var. inflata ) have the same basic characteristics namely, less tumid dorsal than ventral valve, slightly depressed shell, subpentagonal outline, and few but strong ribs. Shi and Grant therefore regard them as a single variable species: C. quadriplicata ( Zieten, 1830) . They suggest combining the varieties C. quadriplicata denecosta and C. quadriplicata var. inflata into a single species: Cymatorhynchia denecosta Alméras, 1966 . Alméras and Elmi (1996) describe a specimen of C. quadriplicata v ar. inflata from Toulon, France, that is larger ( USNM 541691: L, 30.3; W, 29.4 [est.]; T, 24.8), much more gibbous and has finer and more numerous costae (about 26). C. quadriplicata v ar. inflata from Württemberg, Germany, has similar dimensions ( USNM 541692: L, 30.1; W, 33.0; T, 24.4) but the costae are less numerous (20) and sturdier.

Stratigraphic and geographic range.—Bathonain to Callovian; England, France, Jordan, Ethiopia.

Figures

Fig. 4. Serial sections of the rhynchonellide brachiopod Cymatorhynchia quadriplicata (Zieten, 1830). AMNH FI−72369. Bed 21a, Hamam Formation, Arda, Jordan. Numbers describe sectional distance from apex. Abbreviations:c, crus; cb, crural base; dms, dorsal median septum; dp, dental plate; isr, inner socket ridge; osr, outer socket ridge; s, socket; sp, septalial plate; ssm, secondary shell material; t, tooth.