Parallelopora sp.

Huang, Jiayuan, Liang, Kun, Wang, Yue, Kershaw, Stephen, Jeon, Juwan, Li, Yue & Qie, Wenkun, 2022, Stromatoporoids from a Middle Devonian reef in South China and their palaeoecological implication, Acta Palaeontologica Polonica 67 (3), pp. 711-736 : 725-728

Parallelopora sp.

Fig. 9C .

2020 Parallelopora ostiolata Bargatzky, 1881 ; Huang et al. 2020: 3.

Material.— One fragmental skeleton ( NIGP 177057 ) from the Givetian (Middle Devonian) Jiwozhai reef, Dushan Formation , Dushan, Guizhou, South China .

Description.—Skeleton appears to be laminar. Surface features are not visible in cemented limestone. In longitudinal section, the skeleton is made up of conspicuous pachysteles and indistinct pachystromes ( Fig. 9C 1 ). Pachysteles are slen- der, vertically straight, densely distributed, spacing 15–16 per 2 mm, 0.05–0.075 mm in thickness. Pachystromes are thin, rarely exist, commonly replaced by dissepiments. Galleries are extremely narrow, with a width of 0.025 –0.075 mm, infilled with concave dissepiments. In tangential section, the pachysteles interconnect, forming a closed network enclosing autotubes ( Fig. 9C 2 ). Autotubes are circular, 0.025–0.05 mm in diameter. The microstructure is coarsely orthoreticulate.

Remarks.—The present species was preliminarily assigned to Parallelopora ostiolata Bargatzky, 1881 , by Huang et al. (2020) according to the coarsely orthoreticulate microstructure, but the latter shows more thick and sparsely distributed

Fig. 10. Stromatoporoid Stachyodes costulata Lecompte, 1952 , from the Jiwozhai reef, Jiwozhai Member, Dushan Formation, Givetian, Middle Devonian; Dushan, Guizhou, South China. A. NIGP 177058; A 1, longitudinal section of the whole thin section showing the columnar skeleton interconnected through → laminar skeleton in the bottom (arrows); A 2, enlargement of A 1, note the striated microstructure (arrow);A 3, enlargement of A 1, showing autotubes and striated microstructure (arrow). B. NIGP 177059; B 1, tangential section showing the regular autotubes; B 2, enlargement of B 1, note the striated microstructure (arrow).

pachysteles, commonly spacing 5–6, or 8–10 per 2 mm, and with a width of 0.07–0.18 mm ( Lecompte 1952; Galloway and St. Jean 1957; Galloway 1960). However, the poorly preserved single specimen cannot justify the assignment to a new species.

Family Stachyoditidae Khromykh, 1967

Genus Stachyodes Bargatzky, 1881

Type species: Stachyodes verticillata ( M’Coy, 1850) ; Middle Devonian of Eifel , Germany .

Figures

Fig. 9. Stromatoporoids from the Jiwozhai reef, Jiwozhai Member, Dushan Formation, Givetian, Middle Devonian; Dushan, Guizhou, South China. A, B.?Habrostroma laminosum (Lecompte, 1952) A. NIGP 177055; longitudinal section of the laminar form; B. NIGP 177056; B1, longitudinal section of the high domical form; B2, poor preservation of tangential section showing the dense structure; B3, enlargement of B1, showing possible microreticulate microstructure (arrow). C. Parallelopora sp., NIGP 177057; C1, longitudinal section, note the microreticulate microstructure; C2, tangential section showing the autotubes.

Fig. 1. Location and stratigraphy of the Jiwozhai reef in Dushan County, Guizhou, South China. A. Map showing southern Guizhou and northern Guangxi and the studied area in China. B. Locality of the Jiwozhai reef in Dushan County. C. Depositional successions and fossil assemblages of the supposed uppermost Eifelian to lowermost Frasnian in Dushan, Guizhou province (modified after Liao et al. 1979; Liao 2003).Abbreviations:Ei, Eifelian; Fr., Frasnian.

Fig. 2. Field photographs of the Jiwozhai reef. A. A panoramic view of the whole reef unit, with a white rectangle indicating the studied area. Note the reverse fault in the east. B. A general view shows the studied area of the reef unit. C. Enlarged field photo of the reef fragment marked in B, showing the thick or thin laminar stromatoporoids (undulating dashed line) covered on branching tabulate corals (triangles), solitary rugose corals (crosses), dendroid stromatoporoids (squares), bulbous stromatoporoid (circled line), and clay-rich micrites (fine grained sediments between the metazoan skeletons). D. An example of polished block of the Jiwozhai reef limestone showing toppled dendroid or laminar Stachyodes fasciculata Dong in Dong et al., 1989, and encrusting Stictostroma saginatum (Lecompte, 1951) in the upper area. Note the conspicuous digitation of mamelons of Stictostroma saginatum (Lecompte, 1951) in the lower right corner. Sti, Stictostroma saginatum (Lecompte, 1951); Sta, Stachyodes fasciculata Dong in Dong et al., 1989; Tha, Thamnopora cf. pansiensis Tchi, 1966.