Spinatrypa mariaetheresiae, Halamski, 2013

Halamski, Adam T., 2013, Frasnian Atrypida (Brachiopoda) from Silesia (Poland) and the age of the eo-Variscan collision in the Sudetes, Geodiversitas 35 (2), pp. 289-308 : 300-302

Spinatrypa mariaetheresiae n. sp. ( Figs 7 ; 8 )

Spinatrypa aspera – Gunia 1966: 310, 311.

Spinatrypa bifidaeformis – Gunia 1968: 166, pl. 7: 18, 19. TYPE MATERIAL. — Articulated shell MB.B. 2424.2, holotype. 13 paratypes: MB.B.2414-2415; MGUWr 5360s ( Spinatrypa bifidaeformis sensu Gunia, 1966 ; Witoszów, outcrop 15), 5361s ( Spinatrypa aspera sensu Gunia, 1968 ; Witoszów, outcrop 15), 5364s.1- 4, 5365s.

ETYMOLOGY. — In honour of Mary Theresa Olivia Fürstin von Pless, Reichsgräfin von Hochberg, Freifrau zu Fürstenstein (1873-1943), called Daisy, a former owner of the type outcrop, organiser of humanitarian aid during both World Wars.

TYPE HORIZON. — Pogorzała Formation, Late Frasnian.

TYPE LOCALITY. — Abandoned quarry “Lake Daisy”, Mokrzeszów (Oberkunzendorf), Świebodzice Depression, Sudetes, Poland.

STRATIGRAPHIC AND GEOGRAPHIC RANGE. — Świebodzice Depression, Mokrzeszów and Witoszów, Frasnian (most probably in both cases Late Frasnian).

DIAGNOSIS. — Spinatrypa with high, pronounced tongue, sixteen to twenty ribs, stout teeth and large dental cavities.

DESCRIPTION

Shell usually slightly wider than long(W/L from 0.95 to 1.16; mean value 1.06, N=8), subcircular in outline,nearly aequibiconvex to markedly dorsibiconvex, up to 24.0 mm wide (mean value 17.4 mm), rather thick in older specimens. Maximal width and thickness slightly posteriorly to midlength. Apical angle about 120-130°. Anterior commissure uniplicate, its deflexion rounded (more seldom subtrapezoidal) in outline, very high; occupying ⅔ of the shell width. Ventral beak (preserved only in young specimens) acute, nearly straight. Ventral interarea orthocline. Ribs spinose strong, rounded, 3-4 per 5 mm at anterior commissure, new ones appearing by bifurcation. Growth lamellae (seldom preserved) strong, 3-4 per 5 mm in central part of the shell; traces of spine insertion at intersection of growth lamellae with ribs. Interior ( Fig. 8 ). Ventral valve: dental cavities very large; teeth strong and massive. Dorsal valve damaged in apical region in the sectioned specimen; sockets strong, crura ventrally directed.

DISCUSSION

This species is included within Spinatrypa on account of its coarse costation and large dental cavities. Its high, pronounced tongue is more or less constant in adult specimens ( Fig. 7N, S, X , CC).

The great majority of Frasnian representatives of the genus Spinatrypa possess much less pronounced tongue. This is the case of S. bunkeri Day & Copper, 1998 , S. planosulcata (Webster, 1888) , S. rockfordensis (Fenton & Fenton, 1924) , S. thompsoni Day & Copper, 1998 , and S. trulla ( Stainbrook, 1945) from western North America ( Day & Copper 1998), S. ningxiangensis Zhao in Yang et al. 1977 (see Ma 1992), S. subkwangsiensis (Tien, 1938) both from China ( Ma et al. 2006), S. longispina (Rigaux, 1872) from Boulonnais (northern France; see Godefroid 1988), S. plicata ( Rzhonsnitskaya,1964) from Russia ( Rzhonsnitskaya et al. 1998), S. montanensis (Kindle, 1908) from Montana ( Laird 1947), S. tribulosa Norris, 1992 from Arctic Canada ( Norris et al. 1992). This may be said also about approximately coeval Spinatrypa ex gr. bifidaeformis (Tschernyschew, 1887) and Spinatrypa ex gr. semilukiana Lyashenko, 1959 from the Holy Cross Mts. ( Racki & Baliński 1998), and slightly older Spinatrypa semilukiana Ljaschenko, 1959 from the Dębnik Anticline ( Baliński 1979, 2006). Spinatrypa hystrix (Hall, 1858) from New York and S. obsolescens ( Cooper & Dutro, 1982) from New Mexico have very low, obsolescent costae ( Cooper 1944; Cooper & Dutro 1982).

Two Frasnian taxa from New Mexico, Spinatrypa compacta Cooper & Dutro, 1982 and S. trulla decorticata Cooper & Dutro, 1982 may possess a large tongue. The former differs from the Sudetes material in its straight shoulder line and the latter is usually wider ( Cooper & Dutro 1982).

Spinatrypa lambermontensis Mottequin, 2003 from the Late Frasnian of the Vesdre nappe and the Dinant Synclinorium (southern Belgium; see also Mottequin 2008: 501; erroneously reported from the Pragian by Hubert et al. 2007: 260) is quite similar to the form described here in overall shape, yet its ornamentation is slightly finer (usually over 20 ribs in total; 16-20 in the coarse-ribbed variant of our species). Moreover, S. mariaetheresiae possesses large dental cavities, whereas only small dental nuclei are present in S. lambermontensis ( Mottequin 2003: fig. 4).

Spinatrypa rossica Rzhonsnitskaya in Rzhonsnitskaya, Markovskii, Yudina & Sokiran, 1998 from the Late Frasnian of SW Urals may also possess a strong tongue but the ornamentation is very coarse (total number of ribs 10-14; Rzhonsnitskaya et al. 1998). Serial sections of this species have unfortunately not been provided.

In view of the comparison with all available Frasnian taxa of the genus Spinatrypa presented above the material from the Frasnian of the Sudetes is best described as a new species. It may be noted that the two nearest species, namely S. lambermontensis Mottequin, 2003 and S. rossica Rzhonsnitskaya, 1998 are both also Late Frasnian in age. The Givetian species Isospinatrypa givetica Rzhonsnitskaya, 1968 from the Kuznetsk basin ( Rzhonsnitskaya 1975: pl. 24, figs 7, 8) may possess a similar tongue but is always aequibiconvex.

The material from Mokrzeszów contain two forms with similar ornamentation pattern but different ornamentation density. The commoner form has coarser costae and costellae ( Fig. 7 A-Y), whereas the rarer form possesses finer radial ornamentation ( Fig. 7 Z-DD). In view of nearly identical shape (in particular, the characteristic tongue) they have been interpreted as two morphotypes of a single species. A similar dimorphism has been reported in Spinatrypina soetenica (Struve, 1964) (Eifel Mts, Lower Givetian; Copper 1967) and Spinatrypina (Exatrypa) relicta Racki & Baliński, 1998 (Łgawa Hill, Holy Cross Mts, Late Frasnian; Racki & Baliński 1998: 284).

Both Spinatrypa aspera sensu Gunia, 1966 and S. bifidaeformis sensu Gunia, 1968 correspond to Spinatrypa sp. described here. However, the sample of Spinatrypa tubaecostata sensu Gunia, 1966 [non Spinatrypina tubaecostata (Paeckelmann, 1913) ] is a mixture of fragmentarily preserved atrypids (probably all three species described here), indeterminable in large part.

Figures

FIG. 7. — Spinatrypa mariaetheresiae n. sp., Mokrzeszów (Oberkunzendorf), Late Frasnian: A-E, paratype, articulated shell MGUWr 5360s.1 figured by Gunia (1968: pl. 7: 18, 19) as S. bifidaeformis; F-J, paratype, articulated shell MGUWr 5361s.1, corresponding to S. aspera sensu Gunia, 1966; K-O, paratype, articulated shell MB.B.2539; P-T, paratype, articulated shell MGUWr 5360s.2 corresponding to S. bifidaeformis sensu Gunia, 1968; U-Y, holotype, articulated shell MB.B. 2424.2; Z-DD, paratype, articulated shell MB.B.2424.1. A, F, K, P, U, Z, dorsal views; B, G, L, Q, V, AA, ventral views; C, H, M, R, W, BB, lateral views; D, I, N, S, X, CC, posterior views; E, J, O, T, Y, DD, anterior views. Scale bar: 2 cm.

FIG. 8. — Spinatrypa mariaetheresiae n. sp. Serial sections of a slightly dorsally decorticated specimen MGUWr 8998s; Mokrzeszów (Oberkunzendorf),Late Frasnian.Abbreviations (internal structures):cb, crural base;cr, crus;dc, dental cavity;t, tooth.Scale bar:1 mm.