Spinatrypa subkwangsiensis ( Tien, 1938 )

Ma, Xue-Ping, Becker, Ralph Thomas, Li, Hua & Sun, Yuan-Yuan, 2006, Early and Middle Frasnian brachiopod faunas and turnover on the South China shelf, Acta Palaeontologica Polonica 51 (4), pp. 789-812 : 801

publication ID

https://doi.org/ 10.5281/zenodo.13742176

persistent identifier

https://treatment.plazi.org/id/4836037D-D660-6C4B-FFBF-D59CFAC0F870

treatment provided by

Felipe

scientific name

Spinatrypa subkwangsiensis ( Tien, 1938 )
status

 

Spinatrypa subkwangsiensis ( Tien, 1938)

Fig. 10C–G View Fig .

1938 Atrypa aspera var. subkwangsiensis sp. nov.; Tien 1938: 100–101, pl. 8: 1–4, 17.

1983 Spinatrypa subkwangsiensis (Tien) ; Chen 1983: 321, pl. 30: 5a–f.

2002 Spinatrypa subkwangsiensis ( Tien, 1938) ; Ma et al. 2002: 388, fig. 11A–E.

2005 Spinatrypa subkwangsiensis ( Tien, 1938) ; Ma et al. 2005: 441, pl. 1: 9–18.

Material.—One dorsal valve from the middle part of the Longkouchong Formation of the Qiziqiao section. About 50 specimens from the basal part of the Qilijiang Formation, most of which are complete shells.

Discussion.—The dorsal valve figured in Fig. 10C View Fig is about 12.7 mm wide and 12.4 mm long, with about 25 ribs on the whole shell surface and 4.5 ribs per 5 mm at the anterior margin, which is transitional between Spinatrypina douvillei ( Mansuy, 1912) and Isospinatrypa bodini ( Mansuy, 1912) that have respectively about 5 ribs per 5 mm and 4 ribs per 5 mm at the anterior margin (from counting on Mansuy’s 1912 illustrations). However, its seemingly spiny ornamentation and much convex dorsal valve of the studied specimen suggest that it should be assigned to Spinatrypa . It is morphologically consistent with S. subkwangsiensis Group B of Ma et al. (2002: 388, with finer and more ribs than Group A).

Relatively abundant specimens in the basal part of the Qilijiang Formation in the Qiziqiao section ( Fig. 10D–G View Fig for example) are small−sized specimens similar to those reported by Ma et al. (2005, pl.1: 9–18). They are generally less than 10 mm in width, biconvex (in specimens smaller than 8 mm in width) to medium dorsi−biconvex (in larger specimens), with about 18 ribs (for specimens of Fig. 10F, G View Fig ) and 20–25 ribs (for specimens of Fig. 10D, E View Fig ). Larger specimens show spiny bases ( Fig.10E View Fig 3 View Fig ) or traces of spines ( Fig. 10D View Fig 1 View Fig ). A submesothyrid subrounded foramen (0.5 to 0.75 mm in diameter, depending on shell size) is bounded by a pair of deltidial plates on its lower−lateral sides. These specimens of sample QZQ 4 are smaller than Spinatrypa discoforma Chen, 1983 ; they have a dorsi−biconvex profile (versus biconvex to ventribiconvex in S. discoforma ), more ribs (20–25 versus 15–20 in S. discoforma ) and a well developed foramen defined by a pair of deltidial plates (foramen and deltidial plates in S. discoforma are “obsolescent and not present” according to its original description by Chen 1983: 321–322). By comparison with similar−sized specimens of Spinatrypa subkwangsiensis Group A from the Shetianqiao section ( Ma et al. 2002), these specimens seem to possess higher but narrower ribs, much denser growth lamellae, and finer spines or spine bases. It can not be ruled out that they actually are mature specimens and represent a distinct species of Spinatrypa or Isospinatrypa , pending more material available for study and comparisons.

Occurrence.—This species is widely distributed in South China, both geographically and stratigraphically, e.g., in the Givetian–Frasnian interval of central Hunan and northern Sichuan (e.g., Tien 1938; Chen 1983; Ma et al. 2002). The studied specimens are from Beds 14 and 20 of the Qiziqiao section ( Fig. 2 View Fig ), correlated with the Palmatolepis hassi to lower part of the Early Pa. rhenana conodont zones.

Kingdom

Animalia

Phylum

Brachiopoda

Class

Rhynchonellata

Order

Atrypida

Family

Atrypidae

Genus

Spinatrypa

Loc

Spinatrypa subkwangsiensis ( Tien, 1938 )

Ma, Xue-Ping, Becker, Ralph Thomas, Li, Hua & Sun, Yuan-Yuan 2006
2006
Loc

Spinatrypa subkwangsiensis ( Tien, 1938 )

Ma, X. - P. & Copper, P. & Sun, Y. & Liao, W. - H. 2005: 441
2005
Loc

Spinatrypa subkwangsiensis ( Tien, 1938 )

Ma, X. - P. & Sun, Y. - L. & Hao, W. - C. & Liao, W. - H. 2002: 388
2002
Loc

Spinatrypa subkwangsiensis (Tien)

Chen, Y. - R. 1983: 321
1983
Loc

Atrypa aspera var. subkwangsiensis

Tien, C. C. 1938: 100
1938
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