Cleiothyridina deroissyi ( Léveillé, 1835 )

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 : 814-815

Cleiothyridina deroissyi ( Léveillé, 1835)

Figs. 4B, C, I , 15 , 16A.

1835 Spirifer De Roissyi ; Léveillé 1835: 39, pl. 2: 18–20.

1980 Cleiothyridina deroissyi (Léveillé) ; Brunton 1980: 228–229, figs. 23–24.

1984 Cleiothyridina deroissyi (Léveillé) ; Brunton 1984: 59–62, figs. 67–73.

Material.—76 complete shells and more than 110 mostly complete single valves. The majority of the present material came from sample MH 1, but several specimens of the species was found also in samples MH 2 and M2−8.

Remarks.—The specimens from Muhua are characterised by a strongly transverse elliptical to subcircular outline, strongly biconvex shell profile and a median fold and sulcus. The largest shells reach about 20 mm in width. The shells are ornamented with dense, concentric, thin lamellae projecting anteriorly and anterolaterally as flattened spine−like outgrowths arranged in radial rows ( Fig. 15C 4 , H 6 ). On specimens with worn out surface a characteristic reticulate pattern is well seen ( Fig. 15F 4 ).

Internally, an apically perforated cardinal plate and low median myophragm are present in dorsal valves. The dental plates tend to be clearly laterally convex and widely separated when they merge with the valve floor ( Fig. 15E 3). The pair of elongate oval adductor scars separated by low median myophragm is easily distinguishable on large specimens. The dorsal median myophragm is relatively short, about onefourth of the valve length, and does not extend to the anterior margin of the adductor scars. The latter are located clearly posteriorly to the valve midpoint whereas in Cleiothyridina tenuilineata described below the scars reach almost a half of the valve length ( Fig. 16). The outer hinge plates are roughly triangular in shape with posterolateral edges (or inner socket ridges) forming cardinal flanges which are slightly postero−ventrally bent. The conjunct inner hinge plates are sub−trapezoidal in shape and have a thin median ridge. In one well preserved dorsal valve a longitudinal striation is visible on the whole surface of the outer hinge plates ( Fig. 15F 3). Slightly weaker and oblique striation can be observed on the inner hinge plates of the same valve. Most probably this complex striation marks the attachment scars of the pedicle adjustor muscles. The dorsal foramen is relatively small but frequently it seems enlarged by damage ( Fig. 15F 3). The mantle canal system is well impressed especially in large dorsal valves. Four to five pairs of principal canals could be recognised (e.g., 15F 2). The dental plates tend to be laterally convex and widely separated when they merge with the valve floor ( Fig. 15E 3). The pair of elongate oval adductor scars, separated by low median myophragm is easily distinguishable on large specimens.

The described specimens are very similar to the Early Carboniferous Cleiothyridina deroissyi ( Léveillé, 1835) described from the Western Europe (see Brunton 1980, 1984). The species is characterised by a variable shell outline which in adult individuals may be unusually transverse for the genus ( Brunton 1984: 59, fig. 73). Similar variability is observed among Chinese specimens.

Feng (1989) described Cleiothyridina dapoushangensis Feng, 1989 from Dapoushang section (vicinity of Muhua) on the basis of a single, possibly juvenile and slightly incomplete specimen. Unfortunately, this inadequate material is not sufficient to make any reliable comparison with our specimens. Moreover, the type specimen from Dapoushang seems to be lost (Xueping Ma and Ji Qiang personal communication, December, 2009).

Stratigraphic and geographic range.—According to Brunton (1984) C. deroissyi occurs relatively commonly in the Tournaisian of Belgium and less frequently in the Tournaisian– mid−Viséan in the British Isles, now recovered from Tournaisian of southern China.

Figures

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. 15. Athyridoid brachiopod Cleiothyridina deroissyi (Léveillé, 1835) from the Tornaisian Muhua Formation, southern China. A. Complete juvenile shell, PKUM02−0443, in dorsal (A1), lateral (A2), and anterior (A3) views. B, C. Two almost complete shells, PKUM02−0444 (B) and PKUM02−0445 (C), in dorsal (B1, C1), ventral (B2, C2), and anterior (B3, C3) views, and enlargement of ventral valve showing micro−ornamentation (C4). D. Dorsal valve, PKUM02−0446, viewed externally (D1) and internally (D2). E. Ventral valve, PKUM02−0447, in exterior (E1), interior (E2), and the same inclined anteriorly (E3) views. F. Dorsal valve, PKUM02−0448, in exterior (F1) and interior (F2) views and enlarged view of cardinalia (F3) and corroded surface micro−ornamentation (F4). G. Dorsal valve, PKUM02−0449, interior (G1) and enlarged view of cardinalia (G2). H. Complete shell, PKUM02−0450, in dorsal (H1), ventral (H2), lateral (H3), anterior (H4), and posterior (H5) views, and enlargement showing shell micro−ornamentation (H6). All from sample MH1.

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.