Sinalosia rugosa, Ma & Sun & Hao & Liao, 2002

Ma, Xue-Ping, Sun, Yuan-Lin, Hao, Wei-Cheng & Liao, Wei-Hua, 2002, Rugose corals and brachiopods across the Frasnian- Famennian boundary in central Hunan, South China, Acta Palaeontologica Polonica 47 (2), pp. 373-396 : 386

Sinalosia rugosa sp. nov.

Figs. 9T–V , 10A–F .

Holotype: PUM 00017 , well−preserved complete specimen; illustrated in Fig. 10A–C .

Type locality: Southern slope of a small unnamed hill southeast of Daoshitang , Heyi village , Yangqiao Township , Shaodong County, central Hunan Province .

Type horizon: Upper Shetianqiao Formation at a horizon corresponding to uppermost part of bed 22 of the Shetianqiao Formation ( Hou and Wang 1988: 132), late Frasnian (probably Lower Palmatolepis rhenana conodont Zone or younger).

Derivation of the name: It is from well−developed rugae on both valves.

Diagnosis.— Sinalosia characterized by a concavo−convex profile, hinge line about equal to greatest width, ventral valve with cicatrix of attachment very weak to absent, rugae well developed on both valves, and delicate recumbent spines on ventral valve only.

Material.—Over 50 complete and incomplete shells.

Description.—Adult shell generally 2–2.5 cm in width, elliptical in outline, wider than long, concavo−convex in lateral profile, corpus shallow, hinge line about equal to or slightly shorter than greatest width.

Ventral valve moderately convex. Cicatrix of attachment very weak to absent. Interarea well developed; delthyrium small, triangular, closed by pseudodeltidium. Shell surface marked by rugae and alternating weak spines generally lying parallel to surface; hinge spines rare or absent, erect and slightly coarser if present.

Dorsal valve slightly concave, marked by rugae on whole surface; no spines. Interarea low; notothyrium relatively large (nearly equal to delthyrium in size), closed by chilidium, which is penetrated by a bifid cardinal process in some specimens ( Fig. 9T ).

Dorsal interior with a narrow and low median septum extending to about mid−length of shell; postero−ventrally directed bifid cardinal process high, with a small furrow on top of the cardinal process on each side; sockets short but deep; inner socket ridges well developed, posteriorly connected with the cardinal process. Ventral interiors unknown.

Remarks.—It seems that no similar forms have been recorded yet. This would be the first record of Devonian strophalosioids in China.

Occurrence.—Central Hunan in the Shetianqiao section; late Frasnian.

Figures

Fig. 9. A, B. Rhyssochonetes? sp. 1, sample S−Y−2, ventral and dorsal views, PUM 00055; × 3. C–E, S. Rhyssochonetes? sp. 2, sample S−H−0. C. Ventral view, PUM 00062, × 3. D. Dorsal view showing the interarea, PUM 00048, × 5. E. Ventral view, note the orthomorph parallel arranged hinge spines (arrowed), PUM 00061b, × 3. S. Enlargement of arrowed area of E, × 11.5. F–H. Leioproductus hunanensis Liu, 1982, sample C−H, lateral, dorsal and ventral views, PUM 00031, × 2. I. Productella sp. 2, sample C1−0, dorsal view showing some spines present on the valve, PUM 00035, × 3. J, K. Productella lachrymosa var. asiatica Tien, 1938; sample C7. J. Ventral view, PUM 00002, × 1.5. K. Dorsal view, PUM 00032, × 2. L, M. Productella sp. 1, sample S−Y−4.L. Ventral view, PUM 00018, × 2. M. Dorsal view, PUM 00015, × 2. N–R. Praewaagenoconcha linglingensis (Wang, 1956), sample C−H. N. Dorsal view, PUM 00030, × 2. O. Dorsal view, PUM 00034, × 2. P, Q. Ventral and lateral views, PUM 00024; × 2. R. Dorsal interior showing the slit−like sockets, PUM 00059, × 3.3. T–V. Sinalosia rugosa gen. et sp. nov., sample S−Y−2. T. Showing the distinct interarea with ventral pseudodeltidium and dorsal chilidium, which is medially divided by cardinal process as to form a narrow V−shaped slit gap, PUM 01001, × 6. U, V. Lateral and internal views of cardinal process, PUM 01002; × 6.

Fig. 10. A–F. Sinalosia rugosa gen. et sp. nov., sample S−Y−2. A–C. Ventral, dorsal and lateral views of holotype PUM 00017; × 2. D. Ventral view of paratype PUM 00019 showing its chevron ornamentation, × 2. E, F. Ventral and dorsal views of paratype PUM 00021; × 2. G–I. Hypothyridina linglingensis Wang, 1956a; sample S−Y−4, lateral, ventral and posterior views of PUM 00027; × 1.25. J–Q. Hunanotoechia gamma (Tien, 1938), sample S−Y−2. J. Ventral view of PUM 00042 showing the presence of only two sinal plications, × 3. K–O. Lateral, dorsal, posterior, anterior and ventral views of PUM 00051; × 3. P. Dorsal view of PUM 00041 showing a specimen with growth bizarre ventral beak, × 3. Q. Dorsal view of PUM 00054 showing the deltidial plates, × 5. R, S. Hunanotoechia tieni Ma, 1993; sample S−25−2, PUM 00053, enlarged dorsal view (R) showing the deltidial plates and the foramen, × 4 and ventral view (S), × 3.