Habrostroma laminosum ( Lecompte, 1952 )

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

? Habrostroma laminosum ( Lecompte, 1952)

Fig. 9A, B .

1952 Stromatopora laminosa sp. nov.; Lecompte 1952: 276, pl. 55: 3; pl. 56: 1, 2.

1968 Stromatopora laminosa Lecompte, 1952 ; Flügel and Flügel-Kahler 1968: 235.

1968 Parallelopora laminosa ( Lecompte, 1952) ; Mallett 1968: 225, pl. 26: 1–6.

1978 Stromatopora laminosa Lecompte, 1952 ; Wang 1978: 29, pl. 14: 3.

1979 Stromatopora cf. laminosa Lecompte, 1952 ; Yang and Dong 1979: 55, pl. 27: 5, 6.

1982 Stromatopora laminosa Lecompte, 1952 ; Dong and Wang 1982: 37, pl. 9: 5, 6.

1993 Habrostroma laminosum ( Lecompte, 1952) ; Stearn 1993: 222.

1995 Stromatopora laminosa Lecompte, 1952 ; Krebedünkel 1995: 110, pl. 14: 7, 8.

2005 Habrostroma laminosum ( Lecompte, 1952) ; Stadelmaier et al. 2005: 24, pl. 9: 3.

2008 Habrostroma laminosum ( Lecompte, 1952) ; Salerno 2008: 101, pl. 15: 4, 5.

2020 Habrostroma laminosum ( Lecompte, 1952) ; Huang et al. 2020: 14.

Material.— Five specimens from the Givetian (Middle Devonian) Jiwozhai reef, Dushan Formation , Dushan, Guizhou, South China, with two specimens ( NIGP 177055 and NIGP 177056 ) illustrated .

Description.—Skeletons are laminar to high domical, overgrowing on tabulate corals, solitary rugose corals, or other stromatoporoids, commonly 1–3 mm in thickness, with a maximum of 15 mm. Surface features are not visible in cemented limestone. Latilaminae are common, with individual latilaminae in a thickness of 1–3 mm. In longitudinal section, the skeletons are extremely dense ( Fig. 9A, B 1 ), composed of thin laminae and thick pillars. Laminae are continuous, sharply undulose near the mamelons, spacing 8–14 mm per 2 mm, commonly with thickness of 0.02 mm ( Fig. 9A ). Pillars are short and thick, spool-shaped, laterally interconnected to account for the dense structure, spacing 7–10 per 2 mm, 0.1–0.2 mm in thickness. Galleries are tiny, smaller than the pillars, round or rarely elongate, commonly 0.05–0.15 mm in diameter. Mamelons conspicuous, with height of 2–5 mm, with central and branching astrorhizal canals. Dissepiments are distinct in the astrorhizal canals. The central areas of high domical specimens show indistinctive microreticulate structure formed by melanospheres multi-microlaminae ( Fig. 9B 1 ). In tangential section, the skeletons are also densely packed and can hardly be differentiated ( Fig. 9B 2 ). The microstructure locally appears to be melanospheric or striated ( Fig. 9B 2 , B 3 ), probably due to diagenetic alteration. Remarks.—The present specimens resemble Stromatopora laminosa Lecompte, 1952 due to the indistinctive microreticulate structure and diagenetically melanospheric or striated microstructure. This species was assigned by many palaeontologists to Stromatopora Goldfuss, 1826 , for over four decades, but it does not have the typical cassiculate structure. Stearn (1993) revised Stromatopora laminosa into Habrostroma laminosum and we agree with this decision. Although Webby and Zhen (2008), Stearn (2015b), and Stock and Burry-Stock (2019) generally use pachystele and pachystrome to describe the skeleton of Habrostroma Fagerstrom, 1982 , the holotype presented by Fagerstrom (1982) apparently shows isolated longitudinal elements, which are totally different from the vertically interconnected pachysteles. Therefore, we tend to use “laminae” and “pillars” to describe the skeleton of this genus. However, rare specimens in Jiwozhai reef show poor preservation of tangential section, so are not reliably assigned to Habrostroma laminosum .

Stratigraphic and geographic range.—Lower Givetian (Middle Devonian) of Eifel Germany, and Guizhou Province, South China; lower to middle Givetian (Middle Devonian) of Queensland, Australia; Givetian to Frasnian (Middle–Late Devonian) of Dinant Basin, Belgium.

Family Parallelostromatidae Bogoyavlenskaya, 1984

Genus Parallelopora Bargatzky, 1881

Type species: Parallelopora ostiolata Bargatzky, 1881 ; 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.

Fig. 3. Schematic vertical section of stromatoporoids in the Jiwozhai reef (Huang et al. 2020) showing the spatial distribution of different stromatoporoids, note the predominance of the Gerronostromaria grossum Dong, 1974, in the laminar form stromatoporoids.1, Gerronostromaria grossum Dong, 1974; 2, Clathrocoilona spissa (Lecompte, 1951); 3,?Habrostroma laminosum (Lecompte, 1952); 4, Parallelopora sp.; 5, Pseudotrupetostroma porosum (Yang and Dong, 1979); 6, Salairella buecheliensis (Bargatzky, 1881); 7, Stachyodes costulata Lecompte, 1952; 8, Stachyodes fasciculata Dong in Dong et al., 1989; 9, Stachyodes sp.; 10, Stictostroma saginatum (Lecompte, 1951); 11, Synthetostroma actinostromoides Lecompte, 1951. Black, stromatoporoids; gray, other organisms between stromatoporoids.