Hustedia 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 : 818

Hustedia sp.

Fig. 19A .

1999 Hustedia sp. ; Baliński 1999: 445, fig. 4A, B.

Material.—Four damaged shells from samples MH 2, D4, and Mu−42.

Remarks.—The species was reported from the Muhua Formation by Baliński (1999). It is very rare form in the fauna because the recent intensive acid processing of samples resulted in only one additional specimen ( Fig. 19A ). A single nearly complete shell from sample MH 2 is 2.4 mm long and 2.0 mm wide. There are 12 and 13 radial costae on the dorsal and ventral valves, respectively. The low number of radial costae resembles the ribbing characteristic of Hustedia mormoni (Marcou, 1858) , described from the Upper Carboniferous of Nebraska (see Dunbar and Condra 1932). The specimens from Muhua are also similar externally to Hustedia cf. radialis (Phillips, 1836) described from the Early Carboniferous of Staffordshire by Brunton and Champion (1974). H. radialis re−described by Brunton (1984) from Bolland and Fermanagh ( Great Britain) is wider and possesses more radial ribs.

Figures

Fig. 19. Retzioid and nucleospiroid brachiopods from the Tornaisian Muhua Formation, southern China. A. Retzioid Hustedia sp.; nearly complete shell, PKUM02−0468, in dorsal (A1), lateral (A2), and enlarged dorsal (A3) views. B, F–I. Retzioid Acambona sp. B. Umbonal fragment of dorsal valve, PKUM02−0469, in interior (B1) and posterior (B2) views showing complexity of cardinalia. F. Slightly incomplete dorsal valve, PKUM02−0470, in interior (F1) and enlarged interior (F2) views. G, H. Umbonal region of two dorsal valves, PKUM02−0471 (G) and PKUM02−0472 (H), in anterior view with labelled morphology. I. Incomplete ventral valve, PKUM02−0473, in exterior (I1) and interior (I2) views. C–E. Nucleospiroid Nucleospira sp. C. Interior of incomplete dorsal valve, PKUM02−0474. D, E. Two posterior fragments of shell, PKUM02−0475 (D) and PKUM02−0476 (E), in anterior view showing cardinalia; ventral valve at the top. A, D, E, G, and H, SEM micrographs. Samples MH1 (A, C–E) and MH2 (B, F–I).