Productus sp.

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 : 886-890

Productus sp.

Fig. 9O, P .

Material.—Two articulated specimens:MPUM11908 (RCC1- 61b); MPUM11909 (RCC60-6) from mud mound complex of

Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.

Description.—Medium-sized, elongated concavo-convex shell with suboval outline; cardinal margin straight. Ears large, convex. Both valves geniculated. Anterior commissure rectimarginate. Ventral visceral disc convex; geniculation angle about 90°. Trail straight, long, laterally spreading anteriorly. Dorsal valve geniculation angle 90°. Very low fold on trail.

Ornamentation consists of low, rounded ribs with narrow interspaces. Ribs increase in number anteriorly by intercalation. They number 14 per 10.0 mm at geniculation and on trail.

Remarks.—The specimens are close to Productus productus in lacking a ventral sulcus and in having a laterally spreading trail, but differ from it in having a shorter visceral disc and smaller overall dimensions. They may be similar to P. hispidus Muir-Wood, 1928 , in being small-sized, but differ from it in having finer ornamentation.

Tribe Kozlowskiini Brunton, Lazarev, and Grant, 1995

Genus Eomarginifera Muir-Wood, 1930

Type species: Productus longispinus Sowerby, 1814 , from the upper Visean of West Lothian, Scotland .

Remarks.—The genus was erected by Muir-Wood (1930) and then redefined by Muir-Wood and Cooper (1960) to include small posteriorly reticulate productides with moderate ears and six symmetrical halteroid spines on the ventral valve. It includes various species, many from the upper Visean of Great Britain and Ireland ( Muir-Wood 1928, 1930), with a wide morphological variability.

The genus differs from Promarginifera Shiells, 1966 , from the upper Visean of Scotland, assigned to the Retariini Muir-Wood and Cooper, 1960 , in having a flat geniculated dorsal valve, less numerous, more regularly disposed spines on the ventral valve and in lacking dorsal spines. Moreover, Promarginifera has a diagnostic dorsal non-crenulate subperipheral rim dying out on the flanks.

Eomarginifera cf. laqueata ( Muir-Wood, 1928) Fig. 10B–E .

Material.—Four articulated specimens: MPUM 11910 ( RCC 32-26); MPUM 11911 (WI1-41); MPUM 11912 ( RCC 128- 16); MPUM 11913 (WI1-5). Three dorsal valves: MPUM 11914 ( RCC 60-35); MPUM 11915 ( RCC 300-13); MPUM 11916 ( RCC 54-12). All from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian (RCC-, RCK-), and Wensley Dale, Matlock, Derbyshire, UK, Eyam Limestone Formation, upper Brigantian, upper Visean (WI1).

Description.—Small, elongated concavo-convex shell with transversely subtriangular outline, cardinal margin corresponding to maximum width. Ears small, convex, separated by a narrow groove. Both valves geniculated. Corpus cavity deep. Anterior commissure rectimarginate to gently uniplicate. Ventral visceral disc moderately convex; geniculation angle 70°. Trail long; flanks steep. Shallow sulcus starting from visceral disc mid-length. Dorsal visceral disc flat; geniculation angle 90°. Fold very low, rounded.

Ornamentation consists of low, subrounded ribs with narrow interspaces. Ribs number nine per 5.0 mm at the geniculation, eight per 5.0 mm on trail in the specimens from Ricklow (Brigantian; Monsal Dale Limestone Formation), 13 per 5.0 mm at geniculation, 10–12 per 5.0 mm on trail in the specimens from Wensley Dale (upper Brigantian; Eyam Limestone Formation). Visceral discs ornamented by subangular rugae, resulting in a reticulate ornamentation. On the ventral disc, rugae number five per 5.0 mm length anteriorly. Small spines on umbo. Two symmetrical halteroid spines on flanks near geniculation, laterally directed. Two symmetrical halteroid spines on trail at mid-length, bordering the sulcus, 8.0 mm apart from each other, anteriorly directed.

Remarks.—The specimens are assigned to Eomarginifera cf. laqueata based on their convex ventral visceral disc with numerous spine bases, shallow ventral sulcus, and ribs density. They show a shallow ventral sulcus which is similar to the one of the specimens of E. lobata var. flexa ( Muir-Wood, 1928) from the Brigantian, uppermost Visean, of Scotland ( Muir-Wood 1928: pl. 11: 16a–b, 18), but they differ in having a convex, rather than flat, ventral visceral disc. They differ from E. lobata ( Sowerby, 1821b) in having a weaker ventral sulcus and finer ribs; from E. longispina (Sowerby, 1814) in having a deeper sulcus, more convex ventral visceral disc and coarser radial ornamentation.

Tribe Retariini Muir-Wood and Cooper, 1960

Genus Antiquatonia Miloradovich, 1945

Type species: Productus antiquatus Sowerby, 1821b , from the Mississippian of Derbyshire, England .

Remarks.— Antiquatonia differs from Dictyoclostus Muir-Wood, 1930 , in having a smaller-sized shell and a different arrangement of spines on the ventral valve: Dictyoclostus shows ventral spines arranged in a row on ears, in patches on flanks and near the anterior margin, rather than 1–2 rows on ears, one row on flanks and scattered over the visceral disc and trail as Antiquatonia .

Antiquatonia differs from Pugilis Sarycheva, 1949 , in having a shallower corpus, less enrolled ventral valve, more prominent ribs on trail and a different ventral spine arrangement.

Antiquatonia hindi ( Muir-Wood, 1928) Fig. 10F–L .

1880 Productus semireticulatus ( Martin, 1809) ; Davidson 1880: 307 (pars), pl. 35: 1–2.

1928 Productus hindi ; Muir-Wood 1928: 108, pl. 6: 3, 4a–c, 5–6; text-figs. 1–5, 21.

1952 Antiquatonia hindi ( Muir-Wood, 1928) ; Sarycheva and Sokolskaya 1952: 155, pl. 43.

1991 Antiquatonia hindi ( Muir-Wood, 1928) ; Brunton and Tilsley 1991: 292.

2000 Antiquatonia hindi ( Muir-Wood, 1928) ; Brunton et al. 2000: fig. 317: 2c–f.

Material.—Thirteen articulated specimens: MPUM 11917 RCC 13-2); MPUM 11918 ( RCC 50-1); MPUM 11920 ( RCC 123-1); MPUM 11921 ( RCK 15-7); MPUM 11922 (WI1-19); MPUM 11923 (WI1-25); MPUM 11924 ( RCC 2-48; RCC 60- 21; RCC 65TOP-1; RCC 73-20, 24; RCC 110-3b; RCK 15- 35b). Thirteen ventral valves: MPUM 11925 ( RCC 32-6);

MPUM 11927 ( RCC 1B-24b; RCC 2-23b, 29; RCC 3-12a, 16; RCC 8-4; RCC 11-1, 13; RCC 32-1a, 1b; RCC 73-7; RCC 128- 1). Twelve dorsal valves: MPUM 11928 ( RCC 2-50; RCC 3- 4; RCC 32-12b; RCC 40-5a; RCC 42-23, 32; RCC 60-19a, 25; RCC 65G-8b; RCC 123-2; WI1-15a, 26b). Thirteen fragments: MPUM 11929 ( RCC 1-43; RCC 2-36; RCC 3-15c, 23; RCC 32- 15, 21a, 21b; RCC 40-18; RCC 42-1b, 7; RCC 300-8; RCK 15- 17; WI1-13). All from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian (RCC-, RCK-), and Wensley Dale,

Matlock, Derbyshire, UK, Eyam Limestone Formation, upper Brigantian, upper Visean (WI1).

Description.— Medium-sized, concavo-convex shell with transversely subrectangular outline; cardinal margin wide, generally corresponding to the maximum width. Ears wide, flat, poorly separated. Both valves geniculated. Corpus cavity moderately deep. Anterior commissure gently uniplicate. Ventral visceral disc regularly convex; geniculation angle 120°. Trail long, tubiform. Sulcus starting 5.0 mm from umbo, widening and deepening anteriorly, becoming shallower on the trail. Dorsal visceral disc slightly concave; ears flat. Geniculation angle 90°. Low, rounded fold starting 7.0 mm from umbo, widening anteriorly.

Ornamentation consists of low, rounded ribs with narrow interspaces except for the dorsal anterior disc and trail where they may become wider than ribs. Ribs increasing in number by bifurcation, particularly common on trail flanks, and by rare intercalation on the ventral valve; by intercalation on the dorsal valve. They number 10–14 per 10.0 mm, 20.0 mm from the umbo. Visceral discs ornamented by subquadrate rugae, so that generally prominent reticulate ornamentation is formed; rugae number eight per 10.0 mm length. Rugae intersect the cardinal margin at 90°. Spines on ventral valve only: one row on each ear, diverging at a low angle from cardinal margin; one row of large spines diverging from cardinal margin at 30° and extending on trail flanks, set on a rounded ridge. Small spines on ribs scattered on umbonal flanks and trail. Dorsal valve bearing elongated pits in two rows starting near umbo, diverging from the cardinal margin at 30°, and scattered over the visceral disc. Micro-ornamentation of concentric growth lines on both valves.

Cardinal process stout, sessile, trifid, postero-ventrally directed.

Remarks.—The specimens are close in their morphology, dimensions and ornamentation to the specimens of Antiquatonia hindi figured by Muir-Wood (1928) and Brunton et al. (2000). Antiquatonia hindi var. wettonensis ( Muir-Wood, 1928) from the Brigantian, uppermost Visean, of England and Wales, was distinguished by Muir-Wood (1928) based on its flatter visceral disc ( Muir-Wood 1928: fig. 2a–c). Muir-Wood (1928) also stated the variety to be larger and with coarser ornamentation, but there is considerable overlapping in the shell and ornamentation measures given for A. hindi ( Muir-Wood 1928: 110) and A. hindi var. wettonensis ( Muir-Wood 1928: 113) , so the distinctiveness of the variety seems not to be supported.

The specimens differ from Antiquatonia antiquata ( Sowerby, 1821b) in having finer ornamentation and a spinebearing ridge on flanks.

Stratigraphic and geographic range.— Antiquatonia hindi is recorded in the Asbian–Brigantian, upper Visean, to Serpukhovian of Great Britain and Ireland ( Muir-Wood 1928; Mitchell 1971; Brunton and Tilsley 1991; this study) and in the upper Visean of the Moscow Basin ( Sarycheva and Sokolskaya 1952).

Antiquatonia aff. hindi ( Muir-Wood, 1928)

Fig. 10M–Q .

Material.—Five articulated specimens: MPUM 11930 ( RCC 12-8); MPUM 11931 ( RCC 13-3a); MPUM 11932 ( RCC 32-19); MPUM 11933 ( RCC 13-3e; RCC 32-12a). One ventral valve: MPUM 11934 ( RCC 39-19). Four dorsal valves: MPUM 11935 ( RCC 2-8); MPUM 11936 ( RCC 2-5; RCC 12- 3; RCC 13-3b). Four fragments: MPUM 11937 ( RCC 2-27; RCC 11-9a, 11; RCC 300-6). All from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.

Remarks.—The specimens are close to those assigned to A. hindi from the same localities, but differ in being smaller and in having more numerous and prominent spine bases on ribs, on the ventral visceral disc, and more numerous dimples on the dorsal visceral disc. They also have a weaker to absent ventral sulcus.

Antiquatonia insculpta ( Muir-Wood, 1928)

Fig. 11A–F .

1860 Productus semireticulatus ( Martin, 1809) var. sulcatus ; Davidson 1860b: 109, pl. 3: 6–6a.

1928 Productus insculptus ; Muir-Wood 1928: 89, pl. 3: 10a, 11a–c, 12.

1952 Antiquatonia insculpta ( Muir-Wood, 1928) ; Sarycheva and Sokolskaya 1952: 157, pl. 42.

Material.—Eighteen articulated specimens: MPUM 11938 ( RCC 1B-9); MPUM 11939 ( RCC 3-15a); MPUM 11940 ( RCC 42-26); MPUM 11941 ( RCC 110-1b); MPUM 11944 ( RCC 2-25); MPUM 11942 ( RCC 1-9, 31, 56a; RCC 2-1, 4, 54; RCC 3-13b; RCC 11-5; RCC 12-12; RCC 41-4; RCC 60-3, 4b; RCK 15-56). Eight ventral valves: MPUM 11943( RCC 1B-39); MPUM 11945 ( RCC 1-35, 54; RCC 2-53a, 53b; RCC 65G-7; RCC 73-29a; RCC 128-19). Thirteen dorsal valves: MPUM 11947 ( RCC 128-2); MPUM 11948 ( RCC 1-26; RCC 3-2b, 5a, 5b, 15b; RCC 10- 19; RCC 32-9; RCC 43-1a; RCC 60-1a, 11; RCC 65TOP-40; RCC 110-1c). Three fragments: MPUM 11949 ( RCC 32-18; RCC 43-1b; RCC 73-1). All from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.

Description.—Medium-sized, elongated concavo-convex shell with transversely subtriangular outline; cardinal margin corresponding to maximum width. Ears large, concave, separated by a groove. Both valves geniculated. Anterior commissure uniplicate. Ventral visceral disc slightly convex to almost flat anteriorly; geniculation angle 90°. Trail very long, tubiform, convex. Ventral sulcus shallow, starting near umbo. Dorsal valve geniculated at 12.0 mm from the umbo; geniculation angle 45°. Very low fold starting posteriorly to geniculation, extending on trail.

Ornamentation consists of low, rounded ribs with narrow interspaces on visceral discs, wider on trails. Ribs increase by bifurcation on ventral trail, by intercalation on dorsal trail. They number 12 per 10.0 mm, 15.0 mm from the umbo. Ribs undulating anteriorly on ventral trail, may converge on sulcus. Ventral visceral disc bearing subrounded rugae, resulting in reticulate ornamentation. Rugae number five per 5.0 mm length. Rugae intersect the cardinal margin at 90°. Single row of spines on ears, almost parallel to the cardinal margin; one row of large spines on the umbonal slopes diverging from the cardinal margin at 30–45°, continuing on flanks on a low rounded ridge. Large spines scattered on ventral trail.

Cardinal process stout. Lateral ridges slightly diverge from the cardinal margin. Dorsal median septum longer than two-thirds valve length.

Remarks.—The specimens are close in their morphology, dimensions and ornamentation to the specimens of Antiquatonia insculpta figured by Muir-Wood (1928). They differ from A. hindi from the same localities in having shorter visceral discs, smaller-sized adult shells and a lower angle of geniculation. Gutteridge (1990) reported the presence of A. sulcata ( Sowerby, 1821b) from the mud mound complex in Ricklow. However, we can not confirm his report. The specimens of A. insculpta from Ricklow Quarry differ from A. sulcata in having a shorter visceral disc, smaller size and in having fainter ornamentation of narrower ribs.

Stratigraphic and geographic range.— Antiquatonia insculpta is recorded in the Brigantian, uppermost Visean, of England and Scotland (e.g., Muir-Wood 1928; Mitchell 1971; this study) and in the lower Serpukhovian of the Moscow Basin ( Sarycheva and Sokolskaya 1952).

Figures

Fig. 9. Productellidae and Productidae from the Brigantian (uppermost Visean) of Ricklow Quarry, near Monyash, Derbyshire, UK (localities RCC-, RCK-; see Fig. 3). A–E. Krotovia spinulosa (Sowerby, 1814). A. MPUM11886 (RCC73-22a) in ventral view. B. MPUM11889 (RCC3-18) dorsal valve interior and external cast. C. MPUM11891 (RCK15-16) interior and external cast. D. MPUM11892 (RCK15-28) dorsal valve interior and external cast. E. MPUM11887 (RCK15-10) in ventral view. F–K. Breileenia radiata Brunton in Brunton and Lazarev, 1997. F. MPUM11895 (RCC65-1) in anterior (F1), ventral (F2), and lateral (F3) views. G. MPUM11898 (RCC12-1) dorsal valve external cast. H. MPUM11899 (RCC12-7) dorsal valve interior and external cast. I. MPUM11900 (RCC12-15) dorsal valve external cast. J. MPUM11903 (RCC38A-2) fragment in anterior view. K. MPUM11901 (RCC12-23b) dorsal valve external cast. L. Geniculifera keyserlingiana (De Koninck, 1843), MPUM11905 (RCC73-28) in antero-ventral (L1), lateral (L2), and dorsal (L3) views. M. Limbifera sp., MPUM11890 (RCC54-10b), ventral valve in ventral view. N. Carringtonia cf. carringtoniana (Davidson, 1862a), MPUM11906 (RCC2-51) dorsal valve interior and external cast. O. Productus sp., MPUM11908 (RCC1-61b) in ventral view. P. Productus sp., MPUM11909 (RCC60-6) dorsal valve external cast.

Fig. 10. Productidae from the Brigantian (uppermost Visean) of Ricklow Quarry, near Monyash (localities RCC-, RCK-; see Fig. 3) and Wensley Dale, near Matlock (locality WI1; see Fig. 2), Derbyshire, UK. A. Productus cf. productus (Martin, 1809), MPUM11919 (RCC41-3a) in ventral view. B–E. Eomarginifera cf.laqueata (Muir-Wood, 1928). B. MPUM11910 (RCC32-26) in ventral (B1), lateral (B2), and anterior (B3) views. C. MPUM11911 WI1-41) in ventral (C1) and anterior (C2) views. D. MPUM11914 (RCC60-35) dorsal valve interior and external cast. E. MPUM11915 (RCC300-13) dorsal valve external cast. F–L. Antiquatonia hindi (Muir-Wood, 1928). F. MPUM11917 (RCC13-2) in ventral view. G. MPUM11918 (RCC50-1) in anterior view. H. MPUM11920 (RCC123-1) in ventral view. I. MPUM11921 (RCK15-7) in ventral view. J. MPUM11925 (RCC32-6) ventral valve in anterior view. K. MPUM11922 (WI1-19) in ventral (K1), lateral (K2), dorsal (K3), and posterior (K4) views. L. MPUM11923 (WI1-25) in ventral view. M–Q. Antiquatonia aff. hindi (Muir-Wood, 1928). M. MPUM11930 (RCC12-8) in ventral (M1) and posterior (M2) views. N. MPUM11934 (RCC39-19) ventral valve in ventral view.O. MPUM11935 (RCC2-8) dorsal valve external cast. P. MPUM11931 (RCC13-3a) in posterior (P1) and ventral (P2) views. Q. MPUM11932 (RCC32-19) in anterior (Q1) and lateral (Q2) views. Scale bars 10 mm.

Fig. 11. Productidae from the Brigantian (uppermost Visean) of Ricklow Quarry, near Monyash, Derbyshire, UK (localities RCC-, RCK-; Fig. 3). A–F. Antiquatonia insculpta (Muir-Wood, 1928). A. MPUM11938 (RCC1B-9) in anterior (A1) and lateral (A2) views. B. MPUM11939 (RCC3-15a) in antero-ventral view. C. MPUM11940 (RCC42-26) in antero-ventral view. D. MPUM11941 (RCC110-1b) in lateral view. E. MPUM11944 (RCC2-25) ventral valve in ventral view. F. MPUM11947 (RCC128-2) dorsal valve interior and external cast. G, H. Dictyoclostus pinguis (Muir-Wood, 1928). G. MPUM11950 (RCC54-11) ventral valve in ventral view. H. MPUM11951 (RCK15-63a) dorsal valve external cast. I–K. Pugilis cf. kilbridensis (Muir-Wood, 1928). I. MPUM11956 (RCC128-3) dorsal valve interior and external cast. J. MPUM11955 (RCC54-4) ventral valve in anterior (J1) and lateral (J2) views. K. MPUM11954 (RCC2-47) ventral valve in anterior view. L. Pugilis cf. scotica (Sowerby, 1814), MPUM11958 (RCC2-41) in lateral (L1), ventral (L2), and anterior (L3) views. M, N. Buxtonia scabricula (Sowerby, 1814). M. MPUM11959 (RCC1B-13) in ventral view. N. MPUM11960 (RCC35A-11a) in ventral view.