Merospirifer sp.

Sun, Yuanlin & Baliński, Andrzej, 2011, Silicified Mississippian brachiopods from Muhua, southern China: Rhynchonellides, athyridides, spiriferides, spiriferinides, and terebratulides, Acta Palaeontologica Polonica 56 (4), pp. 793-842 : 825

Merospirifer sp.

Fig. 25 .

Material.—Very fragmentary six ventral and three dorsal valves.

Remarks.—This smooth shelled spriferoid is characterised by the presence of thin subparallel dental adminicula and absence of ventral median septum and crural plates. In the apical region of the delthyrium there is a small, strongly indented anteriorly plate which is attached to the dental flanges slightly below the interarea, but sometimes becomes strongly convex ( Fig. 25A 2, A 4 ). Dental adminicula bent medially just below the delthyrial margin then slightly diverge to the valve floor ( Fig. 25D 1 ) similarly as it was noted in Merospirifer linguifera (Phillips, 1836) by Brunton (1984). The surface micro−ornamentation is well preserved on one specimen in the form of elongated, densely packed exopunctae ( Fig. 25A 6 ).

The present very fragmentary material differs from Eomartinioposis Sokolskaya, 1941 by having very weak ventral sulcus. The former differs also from Globispirifer Tachibana, 1964 in having not elongated shell and from Kisilia Nalivkin, 1979 in having smooth shell and strong and long dental adminicula. The specimens are also similar in general shape of the shell to Crassumbo Carter, 1967 but differ in having well differentiated dental adminicula which are not buried in the umbonal callus. The specimens from the Muhua Formation are the most similar both externally and internally to Merospirifer Reed, 1949 which was re−described by Brunton (1984). Stratigraphic and geographic range.—According to Brunton (1984: 96) the genus occurs throughout the Viséan in the British Isles but some closely related species have been also reported from the Tournaisian. The present material is very poor and comes from samples MH1, MH2, M2–8, and GB.

http://dx.doi.org/10.4202/app.2010.0106

Figures

Fig. 25. Martinid brachiopod Merospirifer sp. from the Tornaisian Muhua Formation, southern China. A. Fragment of ventral valve, PKUM02−0512, in exterior (A1), interior (A2), posterior (A3), posterodorsal (A4), and lateral (A5) views, and enlargement of the surface exopunctate micro−ornamentation (A6). B. Fragment of dorsal valve, PKUM02−0513, in exterior (B1) and interior (B2) views, and enlargement of the interior showing cardinalia (B3). C. Fragment of ventral valve, PKUM02−0514, viewed from the interior showing subparallel, thin dental plates. D. Incomplete ventral valve, PKUM02− 0515, in inclined interior (D1), lateral (D2), posterior (D3), and interior (D4) views. Samples MH1 (A), M2–8 (B, C), and MH2 (D). Scale bars 2 mm.

Fig. 4. Shell damage in silicified brachiopods from the Tournaisian Muhua Formation, southern China. A. Drilled ventral valve of Subglobosochonetes gedongguensis Sun and Baliński, 2008, PKUM02−0390, in exterior (A1) and interior (A2) views. B, C. Two shells of Cleiothyridina deroissyi (Léveillé, 1835) with boreholes, PKUM02−0391 (B) and PKUM02−0392 (C), in dorso−lateral (B) and ventral (C) views, respectively. D, E. Two damaged shells of Cleiothyridina tenuilineata (Rowley, 1900) with boreholes, PKUM02−0393 (D) and PKUM02−0394 (E), in dorsal (D1, E1) and enlarged (D2, E2) views. F. Damaged ventral valve of Cleiothyridina tenuilineata (Rowley, 1900), PKUM02−0395, in general exterior (F1) and more detailed (F2) views. G, H. Two shells of Crurithyris cf. nastus Brunton and Champion, 1974 with boreholes, PKUM02−0396 (G) and PKUM02−0397 (H), in general dorsal (G1, H1) and detailed (G2, H2) views. I. Shell of Cleiothyridina deroissyi (Léveillé, 1835), PKUM02−0398, with a few small−sized boreholes in dorsal valve. J. Shell of Cleiothyridina tenuilineata (Rowley, 1900) with a series of small−sized boreholes, PKUM02−0399, in ventral (J1) and enlarged (J2) views. K, L. Two dorsal valves of Cesifornix carteri Baliński and Sun, 2010a, PKUM02−0400 (K) and PKUM02−0401 (L), bored from the exterior (K1, L1) and showing “blister” deposits in the interior (K2, L2) as a response to borings. M. Dorsal valve of Schellwienella sp., PKUM02−0317, showing numerous external borings of a barnacle (M1) and internal “blisters” sealing the damages (M2) (illustrated by Baliński and Sun 2008: fig. 21D; M2 new photograph). N. Koskinoid perforations in posterior region of ventral valve of Serratocrista sp., PKUM02−0402. Samples GB/GT (A, N), MH1 (B–G, I–L), and MH2 (H, M).

Fig. 1. Stratigraphic columns (A) and map (B) of the sampling sites around Muhua and Gedongguan villages in Guizhou Province, southern China (after Sun and Baliński 2008).

Fig. 6. Shell damage and malformation in silicified brachiopods from the Tornaisian Muhua Formation, southern China. A. Incomplete dorsal valve of orthotetide Schuchertella sp., PKUM02−0320, in general external (A1) and more detailed (A2) views showing damage to the middle anterior margin at the earlier stage of growth resulting in bilobate outline of the valve; note also disturbance of median costellae and a later recovery after some arrest of growth (specimen illustrated also by Sun and Baliński 2008: fig. 22C). B, C. Two dorsal valves of orthotetide Lamellispina spinosa Sun and Baliński, 2008, PKUM02−0406 and PKUM02−0407, viewed from the interior showing distortion/malformation of growth due to crowding. D. Seriously damaged ventral valve of spiriferide Celsifornix carteri Baliński and Sun, 2010a, PKUM02−0408, in external (D1) and internal (D2) views showing full recovery after some arrest of growth; note another (subsequent) repaired damage on the left flank of the specimen. E. Incomplete ventral valve of spiriferide Parallelora sp., PKUM02−0409, in external (E1) and enlarged (E2) views showing repaired damage. F. Incomplete ventral valve of spiriferide Celsifornix carteri Baliński and Sun, 2010a, PKUM02−0410, in external (F1) and internal (F2) views showing broken off and repaired the lateral part of the right flank. G. Ventral valve of spiriferide Eochoristites neipentaiensis Chu, 1933, PKUM02−0411, in oblique lateral view showing repaired damage of the right lateral extremity. H. Dorsal valve of spiriferide Eochoristites neipentaiensis, PKUM02−0412, in external (H1) and internal (H2) views with scalloped anterolateral margin of the left flank showing full repair of the damage. Samples MH1 (A–D, F), MH2 (G, H), and GB (E). Scale bars 2 mm.