Clathrodictyida Bogoyavlenskaya, 1969

Wolniewicz, Paweł, 2009, Late Famennian stromatoporoids from Dębnik Anticline ̕ southern Poland, Acta Palaeontologica Polonica 54 (2), pp. 337-350 : 341-342

Order Clathrodictyida Bogoyavlenskaya, 1969 Family Gerronostromatidae Bogoyavlenskaya, 1969 Genus Gerronostroma Yavorsky, 1931

Type species: Gerronostroma elegans Yavorsky, 1931 ; Lower Devonian , Kuznetsk Basin, Russia .

Emended diagnosis.—Laminae planar, continuous, reduced in columns; galleries rectangular in longitudinal sections; pillars rodlike, mostly long or superposed, in central part of columns branching and forming meandering vertical walls; mamelons common, sometimes upwardly extended into columns; astrorhizae indistinct.

Discussion.—Species described here reveal amalgamated network of pillars in central parts of mamelons and columns, considered as typical of the Clavidictyon Sugiyama, 1939 , commonly recognized in Famennian rocks. However, long and superposed pillars are characteristic for genus Gerronostroma . The exact taxonomic position of Clavidictyon remains unclear. This genus is commonly placed in the order Amphiporida , but Stearn (in Stearn et al. 1999) proposed its moving into the order Clathrodictyida . Specimens of Gerronostroma raclaviense sp. nov. from the Raclawka Valley show laminar basal parts with features characteristic for the clathrodictyids (simple laminae, long pillars) and columns with amalgamated central zones, typical of Clavidictyon . This supports Stearn's et al. (1999) interpretation that these two genera are closely related, with Clavidictyon belonging to order Clathrodictyida .

Specimens of Gerronostroma cracoviensis (phases 1, 2) show pillars thickened in upper parts, with conical axial canals. As a result, in longitudinal sections pillars tend to branch dichotomously, resembling species assigned to the genus Anostylostroma . However, pillars dividing upward complexly, characteristic for the latter genus, are absent. The species described is therefore assigned to the genus Gerronostroma . Specimens described as phase 3 of Gerronostroma cracoviensis ( Gürich, 1904) show close similarities (thickened pillars and numerous foramina) with “ Actinostroma cf. miraculum ” from the Famennian of western Germany ( Flügel and Flügel−Kahler 1975). Absence of a hexactinellid pattern in tangential sections suggests that this species should be assigned to the genus Gerronostroma . Stearn and Halim−Diharja (1987) referred Famennian species of Actinostroma to Gerronostroma .

Famennian representatives of the family Gerronostromatidae , with pillars of variable length, short and superposed within single skeleton, are often assigned to genus Clathrostroma Yavorsky, 1960 . Stearn et al. (1999) put this genus in synonymy with Gerronostroma . Thus the species Gerronostroma sp. is placed here in Gerronostroma , although it reveals short rods appearing together with long, superposed pillars.