Serratocrista aff. dalriensis McIntosh, 1974

Carniti, Alessandro P., Porta, Giovanna Della, Banks, Vanessa J., Stephenson, Michael H. & Angiolini, Lucia, 2022, Brachiopod fauna from uppermost Visean (Mississippian) mud mounds in Derbyshire, UK, Acta Palaeontologica Polonica 67 (4), pp. 865-915 : 897-898

? Serratocrista aff. dalriensis McIntosh, 1974

Fig. 13H .

Material.—Two ventral valves: MPUM11997 (RCC10-40); MPUM11998 (RCC10-2) from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.

Description.—Medium-sized ventral valve with a semicircular outline, flat posteriorly, convex anteriorly. Cardinal margin straight, corresponding to maximum width. Anterior commissure rectimarginate. Umbo moderate, straight. Ventral interarea low, broad, apsacline. Convex, smooth pseudodeltidium; no monticulus; perideltidium evident. Apical angle 60°.

Ventral valve covered by low, straight, rounded ribs with flat, commonly broad interspaces. Ribs increasing anteriorly by frequent intercalation. They number 7–10 per 5.0 mm, 30.0 mm from the umbo. Interspaces with faint concentric filae.

Dental plates and ventral median septum absent.

Remarks.—As the specimens are a disarticulated ventral valve and a fragment, no information about their dorsal internal features are available. Based on the absence of a ventral septum and dental plates the specimens seem to belong to a species of Schuchertellinae . They resemble Serratocrista dalriensis from the Namurian (Serpukhovian) of the Midland Valley of Scotland in their broad pseudodeltidium and ribs density. They can be also included in the size range of the type series of S. dalriensis ( McIntosh 1974: 218) , but differ from it by lacking branching costellae.

Figures

Fig. 13. Echinoconchidae, Linoproductidae, Monticuliferidae, Orthotetida, and Orthida from the Brigantian (uppermost Visean) of Ricklow Quarry, near Monyash, Derbyshire, UK (localities RCC-, RCK-; see Fig. 3). A. Echinoconchus punctatus (Sowerby, 1822), MPUM11976 (RCK15-47) in ventral view. B–D. Pustula cf. pustulosa (Phillips, 1836), B. MPUM11989 (RCC128-17a) dorsal valve external cast. C. MPUM11987 (RCC41-1) in ventral view. D. MPUM11988 (RCC128-7) in ventral (D1) and dorsal (D2) views. E, F. Linoprotonia sp. E. MPUM11991 (RCC42-17) in ventral (E1) and lateral E2) views. F. MPUM11992 (RCC60-59) in ventral view. G. Fluctuaria undata (Defrance, 1826), MPUM11926 (RCC300-14) ventral valve in ventral view. H.?Serratocrista aff. dalriensis McIntosh, 1974, MPUM11997 (RCC10-40) ventral valve in ventral view. I. Schellwienella sp., MPUM11995 RCC36-12) ventral valve in ventral view. J, K. Schizophoria (Schizophoria) cf. connivens (Phillips, 1836). J. MPUM12009 (RCC60-48) in ventral view. K. MPUM12010 (RCC1B-7) dorsal valve in dorsal view. L–O. Schizophoria (Schizophoria.) resupinata (Martin, 1809). L. MPUM12003 (RCC1B-4) dorsal valve in dorsal view. M. MPUM11999 (RCC1B-26) in dorsal view. N. MPUM12004 (RCC1B-25) dorsal valve in dorsal view. O. MPUM12005 RCC36-1a) dorsal valve in dorsal view. Scale bars 10 mm.