Breileenia Brunton, 1997

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 : 884

publication ID	https://doi.org/ 10.4202/app.00972.2022
persistent identifier	https://treatment.plazi.org/id/41708783-FFC4-FFA9-8C7E-C876FAC8FC7D
treatment provided by	Felipe
scientific name	Breileenia Brunton
status

Treatment

Genus Breileenia Brunton in Brunton and Lazarev, 1997

Type species: Productus davidsoni Jarosz, 1917 , from the Asbian , upper Visean, of Longnor, Derbyshire, England .

Remarks.—Small specimens of species of Breileenia may be confused with those of Institifera Muir-Wood and Cooper, 1960 , which is characterised by having a gutter anteriorly in the adult stage. However, Breileenia has a shallower corpus cavity and some species with delayed costae starting near the umbo, rather than on trail.

Breileenia radiata Brunton in Brunton and Lazarev, 1997

Fig. 9F–K View Fig .

1997 Breileenia radiata ; Brunton in Brunton and Lazarev 1997: 389, figs. 5, 12–21.

2000 Breileenia radiata Brunton in Brunton and Lazarev, 1997; Brunton et al. 2000: fig. 289: 1f–g.

Material.—Three articulated specimens: MPUM 11895 RCC 65-1); MPUM 11896 ( RCC 32-13; RCC 42-30). Five ventral valve internal casts: MPUM 11897 ( RCC 12-18a; RCC 42- 50; RCC 43-2b; RCC 68-10; RCC 128-4f). Seven dorsal valve external casts: MPUM 11898 ( RCC 12-1); MPUM 11899 RCC 12-7); MPUM 11900( RCC 12-15); MPUM 11901( RCC 12- 23a, 23b); MPUM 11902 ( RCC 12-18b, 18c). Seven fragments: MPUM 11903 ( RCC 38A-2); MPUM 11904 ( RCC 12-22, 26, 28; RCC 35A-9a, 9b; RCC 300-32). 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 subtriangular outline; cardinal margin corresponding to maximum width. Ears small, flat. Cardinal angles right. Corpus cavity shallow. Anterior commissure rectimarginate. Ventral visceral disc poorly convex; geniculation angle 60°. Trail long. Umbo enrolled. Dorsal valve concave, not geniculated, trail long. Fold and sulcus absent.

Ventral visceral disc ornamented by delayed, prominent, subrounded ribs starting 7.5 mm from the umbo, with narrow interspaces. Ribs increase in number anteriorly by bifurcation on flanks. They number 6–7 per 5.0 mm, 15.0 mm from the umbo. Widely spaced (1–1.5 mm) growth lamellae cover all of the valve surface, crossing ribs. Entire valve covered by spine bases, concentrically to quincuncially arranged. Dorsal valve with similar ornamentation, but with rounded dimples instead of spine bases, and ribs interspaces being wider than ribs anteriorly. Micro-ornamentation of sinuous growth lines.

Remarks.—The specimens are close in their dimensions, morphology and ornamentation to the specimens of Breileenia radiata figured by Brunton and Lazarev (1997), including the holotype from the Brigantian, uppermost Visean, of Fall Hill Quarry (Derbyshire). Breileenia radiata had been confused with the closely allied Breileenia davidsoni (Jarosz, 1917) , from the Asbian, upper Visean, of Great Britain and Ireland, until the revision of the species by Brunton ( Brunton and Lazarev 1997). Brunton showed B. radiata to differ from B. davidsoni in having well-developed delayed costae starting near umbo, rather than being restricted anteriorly on trail, and denser spines. Spine bases are mostly not preserved in the specimens from Ricklow Quarry, but costae arise near umbo and are stronger than the ones shown by the specimens of B. davidsoni . Mitchell (1971) recorded specimens of B. davidsoni in the study area from the Monsal Dale and Eyam limestones formations which are likely specimens of B. radiata .

Stratigraphic and geographic range.— Breileenia radiata is recorded from the Brigantian, uppermost Visean of Derbyshire ( Brunton and Lazarev 1997; this study).