Pleuropugnoides pleurodon ( Phillips, 1836 )

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 : 899-903

Pleuropugnoides pleurodon ( Phillips, 1836)

Figs. 14A–G , 15A .

1836 Terebratula pleurodon ; Phillips 1836: 222: pl. 12: 25–28.

1861 Rhynchonella pleurodon ( Phillips, 1836) ; Davidson 1861a: 101, pl. 23: 1–6, non 7, 8–11, non 12–17,?18, 19–21, non 22. (cum syn.)

1890 Rhynchonella pleurodon ( Phillips, 1836) ; Walther 1890: 433, pl. 24: 9a–d.

1900 Rhynchonella pleurodon ( Phillips, 1836) ; Frech and Arthaber 1900: 201, fig. 13: a–d.

non 1917 Rhynchonella (? pugnax) cf. pleurodon ( Phillips, 1836) ; Trechmann 1917: 59, pl. 5: 6–8.

1952 Camarotoechia pleurodon ( Phillips, 1836) ; Sarycheva and Sokolskaya 1952: 176, pl. 46.

non 1965 Coledium pleurodon ( Phillips, 1836) ; Grant 1965: pl. 18: 3.

1966 Pleuropugnoides pleurodon ( Phillips, 1836) ; Ferguson 1966: 355, pl. 23: 1–11.

1968 Camarotoechia pleurodon ( Phillips, 1836) ; Korejwo and Teller 1968: pl. 20: 2–3.

1969 Pleuropugnoides pleurodon ( Phillips, 1836) ; Parkinson 1969: pl. 19: 1–4; pl. 20: 1, 3, 4, non 2.

1974 Pleuropugnoides pleurodon ( Phillips, 1836) ; Brunton and Champion 1974: 819, pl. 108: 1–4.

1984 Pleuropugnoides pleurodon ( Phillips, 1836) ; Brunton 1984: 34– 36, figs. 5–8.

1991 Pleuropugnoides pleurodon ( Phillips, 1836) ; Brunton and Tilsley 1991: 289.

1991 Pleuropugnoides pleurodon ( Phillips, 1836) ; Martinez-Chacon and Legrand-Blain 1992: 117, pl. 5: 5–9.

1995 Pleuropugnoides pleurodon ( Phillips, 1836) ; Kora 1995: 3 q.

2002 Pleuropugnoides pleurodon ( Phillips, 1836) ; Savage et al. 2002: fig. 800: 1a–k.

?2011 Pleuropugnoides pleurodon ( Phillips, 1836) ; El-Shazly 2011: pl. 3: 1, 4.

Material.—Twentyarticulatedshells: MPUM 12011( RCC 49- 22); MPUM 12012 ( RCC 73-9); MPUM 12013 ( RCK 15-4); MPUM 12014 ( RCK 15-15); MPUM 12015 ( RCK 15-19); MPUM 12016 ( RCK 15-29); MPUM 12017 ( RCK 15B-3); MPUM 12018 ( RCC 1-23c; RCC 49-10c, 17, 18, 44; RCC 54- 17c; RCC 73-23a, 23b; RCC 300-9; RCK 15-1d, 1e, 46a, 46c). Three ventral valves: MPUM 12019 ( RCC 1-27b; RCC 129-2; RCK 15-46b). Five dorsal valves: MPUM 12020 ( RCC 41-17b; RCC 48-26b, 40; RCC 49-4; RCK 17-3). Sixteen fragments: MPUM 12020 ( RCC 1-8g; RCC 1B-5b, 12b, 23b; RCC 12- 24; RCC 41-17c; RCC 42-38; RCC 49-8b, 30, 43; RCC 54-9; RCC 65G-24; RCC 73-23b; RCK 15-8b, 41, 46d). All from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.

Description.—Small, dorsibiconvex shell with transversely suboval outline; cardinal margin curved; maximum width at shell mid-length. Anterior commissure strongly uniplicate with zig-zag profile; tongue high, trapezoid. Ventral valve flat posteriorly, gently concave anteriorly. Umbo slightly curved; palintrope orthocline. Foramen submesothyrid. Dorsal valve evenly convex. Dorsal umbo straight; dorsal palintrope orthocline, sealed by the ventral valve. Ventral sulcus and dorsal fold well developed, starting from shell mid-length.

Ornamentation consists of coarse, low, rounded costae becoming high and angular anteriorly, with narrow interspaces. Ventral sulcus usually with four costae; dorsal fold with five costae; five to seven lateral costae. Micro-ornamentation of faint growth lamellae.

There is variability in profile thickness and shape due to variation of the dorsal valve convexity (e.g., RCK 15-15, Fig. 14E ; RCK 15-29; Fig. 14G ). The number of lateral costae is variable, as it is their width: from four to six costae per 5.0 mm width at 5.0 mm from the dorsal umbo.

Juvenile shells are ovatotriangular in outline, equally biconvex, with a narrow body cavity and are ornamented by costae with narrow interspaces (e.g., RCK 15-4, Fig. 15A ). At a length of about 6.0 mm, an incipient tongue develops in the ventral valve (e.g., RCK 15B-3, Fig. 14C ), while an incipient fold in the dorsal one. During ontogeny, they change in shape, from equally biconvex to strongly dorsibiconvex.

Remarks.—The specimens have a more exposed palintrope and more angular costae with respect to the early Visean specimens of Pleuropugnoides pleurodon from Derbyshire (Thorpe Cloud) and Yorkshire (Bolland) on which Ferguson (1966) based his revision of the species. However, both Parkinson (1969) and Brunton and Champion (1974) illustrated specimens of P. pleurodon from the middle Visean of Yorkshire and Derbyshire and the lower Visean of the Manifold Valley (Staffordshire, England) respectively that have angular costae and a rather exposed palintrope.

Brigantian (uppermost Visean) specimens from Ricklow Quarry have four, rarely three costae in the sulcus; thus, they do not support the trend of increasing number of sulcal costae (from two to six) through the Visean envisaged for the species by Parkinson (1969) and recorded also by Brunton (1984).

Pleuropugnoides pleurodon differs from the allied species P. flexistria ( Phillips, 1836) in lacking numerous intercalating and bifurcating costellae and narrower lateral costae with respect to the ones on the folds and sulcus, and from P. greenleightonensis Ferguson, 1966 , as this species has a distinctive rhomboidal outline.

Stratigraphic and geographic range.— Pleuropugnoides pleurodon is recorded in the Visean of Great Britain and Ireland (e.g., Ferguson 1966; Parkinson 1969; Mitchell 1971; Brunton and Champion 1974; Brunton 1984; Brunton and Tilsley 1991; Harper and Jeffrey 1996; Dean 2017; this study), Germany (e.g., Nicolaus 1963), Spain (e.g., Martinez-Chacon and Legrand-Blain 1992), Belgium (e.g., Demanet 1923), the Silesian Basin, Poland and the Czech Republic (Ostrava Formation; e.g., Jirasek et al. 2012; Żakowa 1971), and North Africa (e.g., Pareyn 1961; Massa et al. 1974; Dedok and Hollard 1980; Kora 1995).

Genus Propriopugnus Brunton, 1984

Type species: Conchyliolithus Anomites ( pugnus ) Martin, 1809, from the upper Visean limestone of Castleton, Hope and Little-Longstone, Derbyshire, England.

Remarks.—The genus was erected by Brunton (1984) to include European rhynchonellides with a high fold and sulcus, a small septalium and a few costae originating in the posterior region of the shell. The specimens of P. pugnus figured by Davidson (1861a: pl. 22: 1–15), Parkinson (1954b: pl. 58: 1–15) and Savage et al. (2002: fig. 798: 1a–p) from the Visean of England have costae arising at one-third shell length and not at the umbones, as stated by Savage et al. (2002). Brunton and Tilsley (1991) included in Propriopugnus also Pugnax pseudopugnus ( Parkinson, 1954b) , from the upper Visean of England, which apparently lacks a dorsal median septum ( Parkinson 1954b). Propriopugnus differs from Pugnax in having a lower, rounded fold and in having coarser costae.

Propriopugnus pugnus ( Martin, 1809)

Fig. 14H–L .

1809 Conchyliolithus Anomites ( pugnus ); Martin 1809: pl. 22: 4–5.

1861 Rhynchonella pugnus ( Martin, 1809) ; Davidson 1861a: 97, pl. 22:?1, 2–15. (cum syn.)

1951 Pugnax pugnus ( Martin, 1809) ; Muir-Wood 1951: pl. 4: 3a–c.

1952 Pugnax pugnus ( Martin, 1809) ; Sarycheva and Sokolskaya 1952: 178, pl. 47.

1954 Pugnax pugnus ( Martin, 1809) ; Parkinson 1954b: 564, pl. 58: 1–15.

1984 Propriopugnus pugnus ( Martin, 1809) ; Brunton 1984: 32, figs. 3, 4.

1991 Propriopugnus pugnus ( Martin, 1809) ; Brunton and Tilsley 1991: 289.

2002 Propriopugnus pugnus ( Martin, 1809) ; Savage et al. 2002: fig. 798: 1a–p.

Material.—Thirteen articulated specimens: MPUM 12021 ( RCC 2-55); MPUM 12022( RCC 3-7); MPUM 12023 ( RCC 60- 44); MPUM 12024 ( RCC 73-22b); MPUM 12028 (WI1-33); MPUM 12025 ( RCC 1B-40a; RCC 10-1; RCC 32-20; RCC 41- 18b; RCC 42-25a, 39; RCC 60-8b; RCC 65G-15c). Two dorsal valves: MPUM 12026 ( RCC 60-4d); MPUM 12027 ( RCC 32- 28c). One fragment: MPUM 12029 (WI1-16). 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, dorsibiconvex shell with subpentagonal outline; cardinal margin curved; maximum width attained at shell mid-length. Anterior commissure strongly uniplicate with zig-zag profile; tongue high, trapezoid. Ventral umbo slightly curved; palintrope very low, orthocline to slightly apsacline. Delthyrium probably with deltidial plates. Sulcus developing at one-third shell length. Dorsal umbo straight; palintrope orthocline, sealed by the ventral valve. High fold developing from shell mid-length.

Three simple, rounded costae with broad rounded interspaces developing from shell mid-length on fold, becoming higher and subangular anteriorly. Two faint costae developed on sulcus from shell mid-length. Two poorly defined low coarse costae developing on each flank near to the commissure. Micro-ornamentation of faint concentric growth lines, sporadic lamellae developed.

Short dorsal median septum, approximately 0.3 mm in length.

The juvenile shell has an oval outline, less transverse with respect to the adult shell, an equally biconvex shape and narrow body cavity. The shell is smooth. Sulcus and subelliptical tongue start to develop approximately at 3.5 mm shell length; fold develops later in ontogeny. Tongue becoming subtrapezoidal later in ontogeny.

Remarks.—The specimens show mesial costae, which start at shell mid-length. This is not the most usual pattern of ornamentation in Propriopugnus pugnus that commonly shows mesial costae originating in the posterior half of the shell. However, many specimens attributed to P. pugnus in the literature, as the ones from Ireland figured by Sowerby 1825: pl. 497: 1–5) and some of those figured by Davidson 1861a: pl. 2: 2, 9, 10, 15), have mesial costae originating from shell mid-length, so this feature seems to be contained in the morphological variability of the species. The specimens differ from P. pseudopugnus in having more rounded costae, a higher average number of mesial costae and an incipient dorsal median septum ( Parkinson 1954b).

Stratigraphic and geographic range.— Propriopugnus pugnus is widely reported from Visean units in Great Britain and Ireland (e.g., Davidson 1861a; Parkinson 1954b; Mitchell 1971; Brunton 1984; Brunton and Tilsley 1991; Brand 2011; Dean 2017; this study), Belgium and the eastern side of the Urals Mountains (Davidson 1861a).

Order Spiriferida Waagen, 1883

Suborder Spiriferidina Waagen, 1883

Superfamily Ambocoelioidea George, 1931

Family Ambocoeliidae George, 1931

Genus Crurithyris George, 1931

Type species: Spirifer urei Fleming, 1828 , from the upper Visean of Strathaven, Lanarkshire ( Scotland) .

Remarks.— Crurithyris has no inner hinge plates ( Brunton 1984), which allows to distinguish it from Ambothyris George, 1931 , from the Middle Devonian of Devonshire.

Crurithyris urei ( Fleming, 1828) Fig. 15B .

1793 [unnamed]; Ure 1793: pl. 14: 12.

1828 Spirifer urei ; Fleming 1828: 376.

1859 Spirifera urii Fleming, 1828 ; Davidson 1859: 58 (pars), pl. 12: 13–14. 1862 Spirifera urii Fleming, 1828 ; Davidson 1862 a: pl. 54: 14.?1899 Ambocoelia parva ; Weller 1899: 20, pl. 4: 1–4. 1931 Crurithyris urei ( Fleming, 1828) ; George 1931: 55, pl. 4: 1–4.?1931 Crurithyris magnispina ; George 1931: 50, pl. 5: 1–4. 1965 Crurithyris urei ( Fleming, 1828) ; Pitrat 1965: fig. 546: 6a–d. 1984 Crurithyris urei ( Fleming, 1828) ; Brunton 1984: 66, figs. 83,

85–92. 1991 Crurithyris urei ( Fleming, 1828) ; Brunton and Tilsley 1991: 290.? 1991 Crurithyris magnispina George, 1931 ; Brunton and Tilsley

1991: 290. 2006 Crurithyris urei ( Fleming, 1828) ; Johnson et al. 2006: fig. 1138:

4a–d.

Material.—One articulated specimen: MPUM12030 (RCC 42-25b) from mud mound complex of Ricklow Quarry, Monyash, Derbyshire, UK, Monsal Dale Limestone Formation, Brigantian, upper Visean.

Description.—Small, ventribiconvex shell with suboval outline; cardinal margin straight, extending two-thirds of maximum width. Cardinal angles obtuse, cardinal extremities subangular. Anterior commissure unisulcate. Ventral interarea low, apsacline. Ventral sulcus absent. Dorsal valve evenly convex. Dorsal interarea very low, orthocline to gently anacline. Low, broad sulcus starting from one-third shell length. Shell smooth. Crural bases strong, almost parallel, 1.0 mm long, each forming an angle of 80° with the cardinal margin. Dorsal median septum absent.

Remarks.—The specimen is assigned to Crurithyris urei , instead of the closely allied species C. nastus Brunton and Champion, 1974 , occurring in lower Visean strata of the Manifold Valley (Staffordshire), based on its regularly convex dorsal valve and crural bases. C. nastus shows a dorsal valve becoming flat anteriorly and shorter, diverging crural bases.

Crurithyris magnispina George, 1931 , is very similar to C. urei and was considered as a synonym by Brunton (1984); later Brunton and Tilsley (1991) differentiated it only based on larger adult size. The specimen from Ricklow Quarry falls in the size range for C. urei .

Stratigraphic and geographic range.— Crurithyris urei is recorded in the Asbian–Brigantian (upper Visean) of northern England, Scotland, and Wales (e.g., George 1931; Brunton 1984; Wilson 1989; Brunton and Tilsley 1991; this study) and in the Tournaisian–upper Visean of the Moscow Basin ( Sarycheva and Sokolskaya 1952).

Figures

Fig. 14. Rhynchonellida and Spiriferida from the Brigantian (uppermost Visean) of Ricklow Quarry, near Monyash (localities RCC-, RCK-; Fig. 3) and Wensley Dale, near Matlock (locality WI1; Fig. 2), Derbyshire, UK. A–G. Pleuropugnoides pleurodon (Phillips, 1836). A. MPUM12011 (RCC49-22) in dorsal (A1) and anterior (A2) views. B. MPUM12013 (RCK15-4) in ventral (B1) and dorsal (B2) views. C. MPUM12017 (RCK15B-3) in ventral (C1), dorsal (C2), and anterior (C3) views. D. MPUM12015 (RCK15-19) in ventral (D1) and dorsal (D2) view. E. MPUM12014 (RCK15-15) in lateral (E1), ventral (E2), and posterior (E3) views. F. MPUM12012 (RCC73-9) in lateral (F1), ventral (F2), posterior (F3), and anterior (F4) views. G. MPUM12016 RCK15-29) in ventral (G1), dorsal (G2), and anterior (G3) views. H–L. Propriopugnus pugnus (Martin, 1809).H. MPUM12021 (RCC2-55) in dorsal view.. MPUM12022 (RCC3-7) in dorsal (I1) and anterior (I2) views. J. MPUM12024 (RCC73-22b) in ventral (J1) and anterior (J2) views. K. MPUM12026 RCC60-4d) dorsal valve in dorsal view. L. MPUM12028 (WI1-33) in dorsal view. M.?Fusella sp., MPUM12037 (RCC128-5) ventral valve in ventral view. N, O. Martiniinae gen. et sp. indet. N. MPUM12065 (RCC2-58a) ventral valve in ventral view. O. MPUM12066 (WI1-32) ventral valve in ventral view.P–S. Angiospirifer bisulcatus (Sowerby, 1825). P. MPUM12032 (WI1-12a) in ventral view. Q. MPUM12035 (WI1-11) ventral valve in ventral view. R. MPUM12031 (WI1-10) in lateral (R1), dorsal (R2), ventral (R3), anterior (R4), and posterior (R5) views. S. MPUM12033 (WI1-30) in lateral (S1), dorsal S2), ventral (S3), anterior (S4), and posterior (S5) views. T–V. Latibrachythyris cf. crassa (De Koninck, 1843). T. MPUM12039 (RCC1-34a) ventral valve in ventral view. U. MPUM12038 (RCC1-21) ventral valve in ventral view. V. MPUM12041 (RCC54-17a) ventral valve in ventral (V1) and posterior (V2) views. Scale bars 10 mm.

Fig. 15. SEM images of brachiopod specimens from the Brigantian (uppermost Visean) of Ricklow Quarry, near Monyash, Derbyshire, UK (localities RCC-, RCK-; Fig. 3). A. Pugnacid Pleuropugnoides pleurodon (Phillips, 1836), MPUM12013 (RCK15-4) inventral view.B.Ambocoelid Crurithyris urei (Fleming, 1828), MPUM12030 (RCC42-25b) in ventral view. C. Gillediidid?Balanoconcha sp., MPUM12094 (RCC10-15a) in dorsal view. D, E. Cranaenidid Harttella oakleyi Brunton, 1982. D. MPUM12088 (RCC65G-13), serial section 1.0 mm from the umbo. E. MPUM12088 (RCC48-31), serial section 1.6 mm from the umbo. Detail showing absence of dental plates (D1, E1), focus showing Y-shaped septalium (D2, E2).