Phlogoiderhynchus depressus ( Wang, 1956 )

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 : 795-796

Phlogoiderhynchus depressus ( Wang, 1956)

Fig. 4C .

1956 Paurorhyncha depressa Wang (sp. nov.); Wang 1956: 172, pl. 5: D1–D5.

Material.—Two almost complete but exfoliated or somewhat deformed specimens and one broken ventral valve from sample PY2 (see Fig. 2 ).

Discussion.— Wang (1956) described two associated species from the Late Devonian Yidade (= Itate) Formation of the Poshi (now Panxi) section of eastern Yunnan (material is sparse and neither internal structures nor detailed horizon was given): Paurorhyncha squamosa and P. depressa , the latter differs by its depressed ventral valve. Paurorhyncha is a North American Famennian genus that differs by an elongated−triangular outline.

Major features of the studied specimens of Phlogoiderhynchus depressus include: about 17–20 plications of varied strength on each flank (rarely bifurcating or intercalating), 2–3 pairs of faint parietal plications at anterior margin, and about 9 to 12 in sinus or on fold; dorsal fold extending from mid−length; ornament of weak growth lamellae and weak, dense growth lines; internally, dorsal valve with a high median septum extending to about mid−length, crural base similar to that of Ph. arefactus Veevers, 1959a and Ph. polonicus (Roemer, 1866) (see Biernat and Szulczewski 1975 for internal structure); no dental plates. It differs from Phlogoiderhynchus polonicus as illustrated by Biernat and Szulczewski (1975) and Baliński (2006) by less transverse, but more oval outline, a flat−topped fold, and a less protruding tongue.

Occurrence.—Same as previous. This species is also found in the Panxi section of eastern Yunnan Province; middle part of the Yidade Formation (Early Frasnian).

Figures

Fig. 4. Strophomenid and rhynchonellid brachiopods from the Early and Middle Frasnian of the Panxi and Caiziyan sections. A. Sulcatostrophia? bunapica Veevers, 1959a, PUM05001, sample PY5, Panxi section, Middle Frasnian, dorsal (A1), ventral (A2), area (A3) views, and enlargement of framed area in image A1 (A4). B. Phlogoiderhynchus squamosus (Wang, 1956), PUM05002, sample PY3, Panxi section, Early Frasnian, dorsal (B1), lateral (B2), and posterior (B3) views. C. Phlogoiderhynchus depressus (Wang, 1956), PUM05003, sample PY2, Panxi section, Early Frasnian, dorsal view. D. Pugnax cf. triplicata (Chen in Xu et al. 1978), PUM05004, sample GC20, Caiziyan section, Early Frasnian, lateral (D1: ventral beak broken), dorsal (D2), and anterior (D3: left anterior broken, right lateral anterior slightly broken) views. E. Coeloterorhynchus sp., PUM05005, sample GC21−24, Caiziyan section, Early Frasnian, dorsal (E1: right anterior and right lateral broken), posterior (E2), and lateral (E3) views.

Fig. 2. Stratigraphy and distribution of Early and Middle Frasnian brachiopods in South China. Most but not all known brachiopods are described and illustrated in this paper. For the distribution of atrypids in the Dushan section, for example, see Ma et al. (2005). The stratigraphy of Panxi and the occurrence of Cyrtospirifer sp. are based on Yunnan compiling group (1978) and the occurrence of Stringocephalus in the lower part of the Yidade Formation is as in Xian et al. (1988: 148). The stratigraphy of Dushan and the occurrence of Stringocephalus sp. are as in Liao et al. (1979); the Caiziyan section was re−measured by Long−Ming Wei, Xue−Ping Ma, and Hua Li (personal communication 2005), with coral identifications by Wei−Hua Liao. The stratigraphy of Qiziqiao is based on data of Z.−X. Hu and Z.−Q. Deng in Tan et al. (1987), and the occurrence of Yunnanella sp. is based on Zu−Han Liu (personal communication 2001). Abbreviations: calc., calcareous; argill., argillaceous; C., Cyrtospirifer; Pa., Palmatolepis; Po., Polygnathus; S., Spinatrypina.