We describe two species of reticularioid spiriferid brachiopod, Permophricodothyris grandis (Chao) and Permophricodothyris squamularioides (Huang), from the lower part of the Kamiyasse Formation (Wordian), Kamiyasse—Imo area, South Kitakami Belt, northeastern Japan. Permophricodothyris is known from the middle to upper Permian of the Tethyan region, especially from the upper Permian of South China. The two species from the Kamiyasse—Imo area are representative Tethyan elements of the middle Permian brachiopod fauna of the South Kitakami Belt.
Introduction
Permophricodothyris is a medium- to large-sized reticularioid spiriferid genus, characterized by an oval- to subelliptical-shaped shell, numerous concentric lamellae with double-barreled (biramose) spines along the frontal margin, and posteriorly directed spiralia in the dorsal valve. The genus was established by Pavlova (1965) with Permophricodothyris ovata Pavlova, 1965, from the upper Permian (Dzulfian) of Transcaucasia, Armenia, as type species. Subsequently, Pavlova (1969) clarified the morphological characteristics and classification of the genus, and summarized its stratigraphic and geographic distributions. Shi et al. (2002), in a re-examination of the Chinese specimens of the genus, revealed that 16 species are known from the middle to upper Permian (Wordian-Changhsingian), most of which occur in the upper Permian (Wuchiapingian and Changhsingian) of South China.
In Japan, three Permophricodothyris species have been described by Shimizu (1961) from the upper Permian Takauchi Formation of the Maizuru Belt, southwestern Japan, and one species has been described by Tazawa et al. (2014) from the upper Permian Akasaka Limestone of the Mino Belt, central Japan; these are respectively, Permophricodothyris indica (Waagen, 1882), Permophricodothyris elegantula (Waagen, 1883) and Permophricodothyris cf. calori (Gemmellaro, 1899), and Permophricodothyris horii Tazawa, Ono and Miyake, 2014. In addition, Minato et al. (1979) figured Permophricodothyris cf. caroli (Gemmellaro) from the lower part of the Kanokura Series (equivalent to the lower part of the Kamiyasse Formation) of Imo, South Kitakami Belt, northeastern Japan.
In this paper we describe two species of Permophricodothyris from the lower part of the Kamiyasse Formation (Wordian) in the Kamiyasse-Imo area, South Kitakami Belt (southern Kitakami Mountains), northeastern Japan, Permophricodothyris grandis (Chao, 1929) and Permophricodothyris squamularioides (Huang, 1933). Among the Kamiyasse-Imo specimens, a conjoined shell specimen of Permophricodothyris grandis, numbered NU-B1962, is important for the well preserved posteriorly directed spiralia in the dorsal valve; which is the most diagnostic character of the genus Permophricodothyris. The specimens are registered and housed in the Hokkaido University Museum, Sapporo, Japan (UHR) and in the Department of Geology, Niigata University, Niigata, Japan (NU-B).
Stratigraphy
The stratigraphy of Permian rocks in the Kamiyasse—Imo area has been studied by Shiida (1940), Kambe and Shimazu (1961), Tazawa (1973, 1976), Misaki and Ehiro (2004) and Shiino et al. (2011). The specimens described herein were collected by K. Nakamura and the first author (J. Tazawa) from grey to greenish grey finegrained sandstone and dark grey argillaceous limestone from the lower part of the Kamiyasse Formation (designated by Misaki and Ehiro, 2004) in the Kamiyasse-Imo area. The lower part of the Kamiyasse Formation has been assigned to the Wordian based on ammonoids (Ehiro and Misaki, 2005) and brachiopods (Tazawa, 2014), or to the Midian (probably equivalent to the late Wordian) based on fusulinids (Kobayashi et al., 2009). The topographic and stratigraphic locations of the fossil localities (KF18, KF28, KF62, KF79, KF94, KF217 and KF218) are described below and indicated in Figures 1 and 2, respectively.
Figure 1.
Map showing the fossil localities KF18, KF28, KF62, KF79, KF94, KF217 and KF 218 in the Kamiyasse-Imo area (using the topographical map “Shishiori” scale 1:25,000 published by the Geospatial Information Authority of Japan).
Glossary
KF18:
Upper Shigejisawa Valley (38°59′06″N, 141°31′49″E); dark grey argillaceous limestone of the lower part of the Kamiyasse Formation, with P. squamularioides.
KF28:
Upper Minamizawa Valley (38°59′08″N, 141°31′02″E); dark grey argillaceous limestone of the lower part of the Kamiyasse Formation, with P. squamularioides.
KF62:
Upper Minamizawa Valley (38°59′21″N, 141°31′01″E); greenish grey fine-grained sandstone of the lower part of the Kamiyasse Formation, with P. grandis.
KF79:
Upper Shigejisawa Valley (38°59′07″N, 141°31′40″E); dark grey argillaceous limestone of the lower part of the Kamiyasse Formation, with P. grandis.
KF94:
Upper Minamizawa Valley (38°59′30″N, 141°31′08″E); dark grey argillaceous limestone of the lower part of the Kamiyasse Formation, with P. squamularioides.
KF217:
Upper Imosawa Valley (38°59′55″N, 141°31′4″E); greenish grey fine-grained sandstone of the lower part of the Kamiyasse Formation, with P. grandis and P. squamularioides.
KF218:
Upper Imosawa Valley (38°59′55″N, 141°31′16″E); dark grey argillaceous limestone of the lower part of the Kamiyasse Formation, with P. grandis.
Systematic descriptions
Order Spiriferida Waagen, 1883
Suborder Delthyridina Ivanova, 1972
Superfamily Reticularioidea Waagen, 1883
Family Elythidae Fredericks, 1924
Subfamily Phricodothyridinae Caster, 1939
Genus
Permophricodothyris
Pavlova, 1965
Type species.—Permophricodothyris ovata Pavlova, 1965.
Figure 2.
Generalized columnar section of the Kamiyasse Formation in the Kamiyasse-Imo area, showing the fossil horizons KF18, KF28, KF62, KF79, KF94, KF217 and KF 218 (modified and adapted from Tazawa, 1976).
Permophricodothyris grandis
(Chao, 1929)
Figure 3
Squamularia grandis Chao, 1929, p. 97, pl. 11, figs. 1-3; Jin et al., 1974, p. 312, pl. 164, figs. 17–19; Yang et al., 1977, p. 452, pl. 179, fig. 11; Feng and Jiang, 1978, p. 296, pl. 105, figs. 2, 3; Tong, 1978, p. 261, pl. 91, fig. 2; Liao, 1980, pl. 8, figs. 50, 51; Liu et al., 1982, p. 214, pl. 158, fig. 1; Wang et al., 1982, p. 248, pl. 94, fig. 10; Ding and Qi, 1983, p. 412, pl. 139, fig. 10; Yang, 1984, p. 238, pl. 38, fig. 23; Xu, 1987, p. 235, pl. 16, figs. 4–9; Kotlyar, 1989, pl. 24, figs. 6–8; Zeng et al., 1995, pl. 13, figs. 1, 2.
Permophricodothyris grandis (Chao). Licharew and Kotlyar, 1978, pl. 22, fig. 3; Zhan, 1979, p. 97, pl. 8, figs. 1, 2, 4–6, text-fig. 19; Shi et al., 2002, p. 378, figs. 3B-3C, 4B, 5.1–5.13, 6.1–6.9.
Material.—Six specimens from KF62, KF79, KF217 and KF218: (1) internal moulds of two conjoined shells, with external moulds of the ventral valves, NU-B1961, 1962; (2) external and internal moulds of two ventral valves, NU-B1963, 1964; (3) external casts of two ventral valves, NU-B1965, 1966.
Description.—Shell large in size for genus, longer than wide, ovate in outline, with greatest width slightly anterior to midlength; length about 61 mm, width about 48 mm in the largest specimen (NU-B1965). Ventral valve gently and unevenly convex in lateral profile, most convex in umbonal region; umbo small, pointed, and slightly incurved; interarea moderately high, slightly concave; sulcus broad and shallow. Dorsal valve also gently convex, but less convex than the opposite valve. External surface of ventral valve ornamented with numerous, regular concentric lamellae, with a row of very fine, biramose spine bases on the anterior margin; numbering 6–8 lamellae in 3 mm, and 9–10 spine bases in 1 mm near lateral margin of ventral valve. Internally posteriorly directed spiralia (coiling axes of spires) are preserved in one specimen (NU-B1962) (Figures 3.3b, 3.3c). Other internal structures of both ventral and dorsal valves are not well preserved.
Remarks.—These specimens are referred to Permophricodothyris grandis (Chao, 1929), from the Lungtan Formation of Zhejiang, eastern China, in their large size, slightly elongate oval outline, and in having a broad and shallow sulcus on the ventral valve. Permophricodothyris indica (Waagen, 1883, p. 542, pl. 43, fig. 6; pl. 44, fig. 2), from the Wargal Formation of the Salt Range, Pakistan, is distinguished from P. grandis by its nearly equidimensional shell and shallower ventral sulcus. The type species, Permophricodothyris ovata Pavlova (1965, p. 135, figs, le, 2–4), from the upper Permian (Dzulfian) of Transcaucasia, is clearly distinguished from P. grandis by its smaller size, more elongate outline and shallower ventral sulcus.
Distribution.—Wordian-Changhsingian: northwestern China (Shaanxi), eastern Russia (South Primorye), northeastern Japan (South Kitakami Belt), eastern China (Zhejiang and Jiangxi), central-southern China (Hubei, Hunan, Guangdong and Guangxi) and southwestern China (Guizhou and Sichuan).
Figure 3.
Permophricodothyris grandis (Chao) from the lower part of the Kamiyasse Formation in the Kamiyasse-Imo area. 1, NU-B1961; 1a, external mould of ventral valve; 1b, external latex cast of ventral valve; 1c, d, ventral and dorsal views of internal mould of ventral valve; le, f, enlarged rows of spine bases in the external mould of ventral valve; 2, NU-B1965; external cast of ventral valve; 3, NU-B1962; 3a, b, ventral and dorsal views of internal mould of ventral valve; 3c, enlarged internal mould of dorsal valve, showing posteriorly directed coiling axes of spires. Scale bars represent 1 cm, except for le and 1f.
Figure 4.
Permophricodothyris squamularioides (Huang) from the lower part of the Kamiyasse Formation in the Kamiyasse-Imo area. 1, UHR12582; la, b, external mould and external latex cast of ventral valve; lc-f, ventral, dorsal, anterior and posterior views of internal mould of conjoined shell; 2, NU-B1969; 2a-c, ventral and dorsal views of internal mould with shell material of conjoined shell; 3, NU-B1970; 3a, external mould of ventral valve; 3b, internal mould of ventral valve; 3c, d, enlarged rows of spine bases and interspinous pustules in the external mould of ventral valve; 4, NU-B1972; 4a, b, external mould and external latex cast of ventral valve. Scale bars represent 1 cm, except for 3c and 3d.
Permophricodothyris squamularioides
(Huang, 1933)
Figure 4
Martinia squamularioides Huang, 1933, p. 50, pl. 7, fig. 2, pl. 8, fig. 8.
Squamularia squamularioides (Huang). Feng and Jiang, 1978, p. 295, pl. 105, fig. 1; Tong, 1978, p. 261, pl. 90, fig. 11; Liao, 1979, pl. 1, fig. 23; Liao, 1980, p. 266, pl. 7, figs. 36, 37; Yang, 1984, p. 238, pl. 38, fig. 20; Zeng, 1995, pl. 14, figs. 6, 8.
Phricodothyris cf. caroli (Gemmellaro). Minato et al., 1979, pl. 67, fig. 7.
Permophricodothyris squamularioides (Huang). Shen and Zhang, 2008, figs. 5.24–5.30.
Material.—Eight specimens from KF18, KF28, KF94 and KF217: (1) external and internal moulds of three conjoined shells, NU-B 1967-1969; (2) internal moulds of three conjoined shells, with external moulds of the ventral valves, NU-B 1970, 1971, UHR12582; (3) external and internal moulds of a ventral valve, NU-B1972; (4) external cast of a ventral valve, NU-B 1973.
Description.—Shell medium in size for genus, elongate oval in outline, with greatest width at two-thirds length from umbo; length 36 mm, width 30 mm in the largest specimen (UHR12582). Ventral valve moderately and unevenly convex in lateral profile, most convex in umbonal region; umbo small, pointed, incurved, but not overhanging hinge line; interarea very high, slightly concave; sulcus narrow, deep, originating just anterior from beak, and extends to anterior margin of valve. Dorsal valve gently convex in lateral profile; fold narrow and moderately high. External surface of both valves ornamented with regularly spaced growth lamellae, with a row of numerous dense spine bases and very fine interspinous pustules at frontal margin; numbering 4-5 lamellae in 3 mm, and 9 spine bases in 1 mm near anterior margin of ventral valve. Internal structures of both valves not well preserved.
Remarks.—Among the present material, the best preserved and largest specimen (UHR12582) was figured by Minato et al. (1979, pl. 67, fig. 7) as Phricodothyris cf. caroli (Gemmellaro, 1899). But the Kitakami specimens can be referred to Permophricodothyris squamularioides (Huang, 1933), from the upper Permian of Guizhou, southwestern China, by the ventral valve of medium size, elongate oval outline, and having a distinct ventral sulcus. Permophricodothyris calori (Gemmellaro, 1899), redescribed by Pavlova (1969, p. 103, pl. 10, fig. 1) on the specimens from the upper Permian of the Caucasus Mountains, differs from P. squamularioides in its larger size and shallower ventral sulcus. The preceding species, Permophricodothyris grandis (Chao, 1929) is readily distinguished from the present species by its larger size, less elongate outline, and wider and shallower ventral sulcus.
Distribution.—Wordian-Changhsingian: northeastern Japan (South Kitakami Belt), central-southern China (Hubei and Hunan) and southwestern China (Guizhou and Sichuan).
Acknowledgements
Sincere thanks are due to Koji Nakamura (Professor Emeritus of Hokkaido University) for providing part of the material, and to Guang Rong Shi (Deakin University, Melbourne) and Shuzhong Shen (Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing) for their valuable comments and suggestions on the manuscript.
