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Pennastroma
Classification
Phylum:
Porifera
Class:
Stromatoporoidea
Order:
Labechiida
Superfamily:
Unknown
Family:
Stylostromatidae
Formal Genus Name and Reference:
Pennastroma DONG, 1964, p. 296
Type Species:
P. yangi, OD
Images
(Click to enlarge in a new window)
Fig. 403, 2a-d. *P. yangi, lower part of Shizixu Formation, between Huangjin and Muliu, Luocheng district, northern part of Guangxi Province, holotype, NIGP, Kw047-2 (14160-14162), a, longitudinal section, thin section no. 14162, X2, b, obliquely oriented section, thin section no. 14161, X3.5, cenlarged longitudinal section, thin section no. 14162, X2, d, longitudinal section, thin section no. 14160 , X3.5 (Webby, 2012c, courtesy of Dong De Yuan, see also Dong, 1964, pl. 4, 3-5).
Synonyms
Geographic Distribution
Australia (Bonaparte basin), China (Guangxi, Guizhou, Hunan), ?Uzbekistan
Age Range
Beginning Stage in Treatise Usage:
Upper Devonian (Famennian)
Beginning International Stage:
Famennian
Fraction Up In Beginning Stage:
0
Beginning Date:
371.1
Ending Stage in Treatise Usage:
Upper Devonian (Famennian)
Ending International Stage:
Famennian
Fraction Up In Ending Stage:
100
Ending Date:
359.3
Description
Pinnately arranged, composite, platelike pillars developing within rather narrowly centralized, upwardly arching (possibly mamelon) columns as upwardly and outwardly splayed elements on either side of a more continuous, centralized, platelike structure, or grading into areas where central plate has mainly lateral, yard-arm-type offsets, best represented in obliquely oriented sections, in other areas these composite pillars may either branch, maintain their rather sinuous courses, or develop breaks in upward continuity, broad, intercolumnar spaces composed dominantly of large, complete to near complete, weakly convex to flattened, or concave cyst plates, in places these may alternate with one or more rows of small, imbricated cyst plates that seldom extend entirely across an intercolumnar space, successive rows of tiny, imbricated cyst plates are most commonly intermeshed with pillar offsets within uparching columns, denticles (and short pillars) of intercolumnar spaces are usually confined to tops of more complete cyst plates. [This genus differs from Stylostroma in displaying more concentrated, centralized, columnar areas with innumerable well-developed lateral (yard arm) offsets from its platelike pillars. However, MiSTiaen, Hou, and Wu (1997) questioned the validity of the genus Pennastroma based on a study of material from Famennian deposits in the Etaoucun section of the Guilin region, Guangxi province. They identified their species as belonging to Stylostroma, claiming that features—in longitudinal sections, pectinate and penniform aspects of the pillars, and in tangential sections, the V-shaped outlines of pillars—were not diagnostic, therefore arguing that Dong’s (1964) original genus Pennastroma was a junior synonym of Stylostroma GorSKy, 1938. But MiSTiaen, Hou, and Wu (1997) did not study (or revise) the original type material of Pennastroma (P. yangi ) housed in Nanjing, nor use comparative material from the original type locality (Luocheng area, Guangxi province), nor attempt to compare their species with species of Stylostroma (more than 10 species) already described from the Famennian of southern China (Dong, 1964; Wang, 1978b, 1978c, 1988). The case for relegating Pennastroma to junior synonomy within Stylostroma is, therefore, not based on comparisons between the same or similar type material and should be rejected. It remains, however, a matter of concern that so few, well-oriented, tangential sections have been used to describe Pennastroma and related taxa, preventing their three-dimensional form from being fully
evaluated.
References
Museum or Author Information
Classification
Phylum:
Porifera
Class:
Stromatoporoidea
Order:
Labechiida
Superfamily:
Unknown
Family:
Stylostromatidae
Formal Genus Name and Reference:
Pennastroma DONG, 1964, p. 296
Type Species:
P. yangi, OD
Images
(Click to enlarge in a new window)
Fig. 403, 2a-d. *P. yangi, lower part of Shizixu Formation, between Huangjin and Muliu, Luocheng district, northern part of Guangxi Province, holotype, NIGP, Kw047-2 (14160-14162), a, longitudinal section, thin section no. 14162, X2, b, obliquely oriented section, thin section no. 14161, X3.5, cenlarged longitudinal section, thin section no. 14162, X2, d, longitudinal section, thin section no. 14160 , X3.5 (Webby, 2012c, courtesy of Dong De Yuan, see also Dong, 1964, pl. 4, 3-5).
Synonyms
Geographic Distribution
Australia (Bonaparte basin), China (Guangxi, Guizhou, Hunan), ?Uzbekistan
Age Range
Beginning Stage in Treatise Usage:
Upper Devonian (Famennian)
Beginning International Stage:
Famennian
Fraction Up In Beginning Stage:
0
Beginning Date:
371.1
Ending Stage in Treatise Usage:
Upper Devonian (Famennian)
Ending International Stage:
Famennian
Fraction Up In Ending Stage:
100
Ending Date:
359.3
Description
Pinnately arranged, composite, platelike pillars developing within rather narrowly centralized, upwardly arching (possibly mamelon) columns as upwardly and outwardly splayed elements on either side of a more continuous, centralized, platelike structure, or grading into areas where central plate has mainly lateral, yard-arm-type offsets, best represented in obliquely oriented sections, in other areas these composite pillars may either branch, maintain their rather sinuous courses, or develop breaks in upward continuity, broad, intercolumnar spaces composed dominantly of large, complete to near complete, weakly convex to flattened, or concave cyst plates, in places these may alternate with one or more rows of small, imbricated cyst plates that seldom extend entirely across an intercolumnar space, successive rows of tiny, imbricated cyst plates are most commonly intermeshed with pillar offsets within uparching columns, denticles (and short pillars) of intercolumnar spaces are usually confined to tops of more complete cyst plates. [This genus differs from Stylostroma in displaying more concentrated, centralized, columnar areas with innumerable well-developed lateral (yard arm) offsets from its platelike pillars. However, MiSTiaen, Hou, and Wu (1997) questioned the validity of the genus Pennastroma based on a study of material from Famennian deposits in the Etaoucun section of the Guilin region, Guangxi province. They identified their species as belonging to Stylostroma, claiming that features—in longitudinal sections, pectinate and penniform aspects of the pillars, and in tangential sections, the V-shaped outlines of pillars—were not diagnostic, therefore arguing that Dong’s (1964) original genus Pennastroma was a junior synonym of Stylostroma GorSKy, 1938. But MiSTiaen, Hou, and Wu (1997) did not study (or revise) the original type material of Pennastroma (P. yangi ) housed in Nanjing, nor use comparative material from the original type locality (Luocheng area, Guangxi province), nor attempt to compare their species with species of Stylostroma (more than 10 species) already described from the Famennian of southern China (Dong, 1964; Wang, 1978b, 1978c, 1988). The case for relegating Pennastroma to junior synonomy within Stylostroma is, therefore, not based on comparisons between the same or similar type material and should be rejected. It remains, however, a matter of concern that so few, well-oriented, tangential sections have been used to describe Pennastroma and related taxa, preventing their three-dimensional form from being fully
evaluated.