Eridotrypellidae Morozova, 1961

Morozova, Iraida P., B. Weis, Olga & Racki, Grzegorz, 2002, Emergence and extinction of the Givetian to Frasnian bryozoan faunas in the Kostomłoty facies zone, Holy Cross Mountains, Poland, Acta Palaeontologica Polonica 47 (2), pp. 307-317 : 311-312

Family Eridotrypellidae Morozova, 1961 Genus Eridotrypella Duncan, 1939

Type species: Batostomella obliqua Ulrich, 1890 . Middle Devonian, Hamilton Group; North America (Michigan).

Eridotrypella arguta Morozova and Weis , sp. nov. Figs. 4F , 5A–C .

Holotype: PIN 4873 /5, Fig. 5A–C .

Type locality: Holy Cross Mts (Central Poland), Górno, Józefka Hill (set C), middle Wietrznia Beds; Upper Devonian, middle Frasnian (? Pa. punctata Zone ).

Derivation of the name: From Latin argutus, expressive.

Material.—Five incomplete colonies, 13 thin sections, PIN 4873/5–4873/9.

Diagnosis.— Eridotrypella arguta sp. nov. resembles in many characters E. valentinae Morozova, 1961 from the Givetian of Russia (Kuzbas), but is distinguished in having fewer diaphragms (1–2 against 4–6) and in having larger diameter of autozooecial apertures (0.18–0.20 mm against 0.11–0.12 mm).

Description.—Colony ramose with branches 1.5–2.5 mm in diameter. Exozone is very thick (0.8–0.9 mm). Diameter of the endozone 0.6–0.7 mm. Zooecial walls in the exozone with transversely laminated structure, not beaded. Thickness of the walls in the exozone 0.02–0.05 mm. Endozonal walls are about 0.015 mm thick. Autozooecia curve gently into the exozone and turn to the surface at an acute angle. Diaphragms thin, rare, one to two per autozooecium located only in the exozone. Autozooecial apertures polygonal, 0.18–0.20 mm in diameter, 7 or 8 in 2 mm, rarely 9. Distance between neighbouring apertural centers both longitudinally and diagonally 0.21–0.27 mm. Exilazooecia are short, very rare and small, of subcircular outline. Diameter of the exilazooecial apertures 0.04–0.06 mm. Numerous small pores (capillaries) about 0.003 mm in diameter pierce all walls in the exozone and form small accumulations around the stellatopores at junctions of the zooecial walls.

Remarks.—Dense accumulations of capillaries on the colony surface (stellatopores) surrounding each autozooecial aperture are characteristic of the holotype of Eridotrypella arguta and other species of this genus. Many authors (e.g., Duncan 1939; Morozova 1961; Astrova 1978) assumed them erroneously to be acanthopores (acanthozooecia) which, in fact, lack them in this genus, as well as Eostenopora , the other genus of the family Eridotrypellidae . Therefore, diagnoses of these generashould be revised.

Occurrence.—Only the type locality.

Figures

Fig. 4. A–C. Lioclema celebratum Morozova, 1961. Tangential section (A), longitudinal section (B), and transverse section (C) of the specimen PIN 4873/41 from Givetian of Laskowa Quarry, Laskowa Góra Beds. D, E. Atactotoechus polygonius Bigey, 1988. Tangential section (D), longitudinal section (E) of the specimen PIN 4873/43 from Givetian of Laskowa Quarry, Laskowa Góra Beds. F. Eridotrypella arguta Morozova and Weis, sp. nov. Tangential section of the paratype PIN 4873/6 from Frasnian of Górno, Józefka Hill, Wietrznia Beds. Scale bars 1 mm.

Fig. 5. A–C. Eridotrypella arguta Morozova and Weis, sp. nov. Tangential section with capillaries indicated with arrows (A), oblique longitudinal section (B), transverse section (C) of the holotype PIN 4873/5 from Frasnian of Górno, Józefka Hill, Wietrznia Beds. D–H. Eridotrypella exserta Morozova and Weis, sp. nov. Tangential section (D), oblique tangential section with exilazooecia forming small accumulations in macula (E), transverse section of the main stem (F), longitudinal section of a lateral branch (G), longitudinal section of the main stem (H) of the holotype PIN 4873/20 from Frasnian of Górno, Józefka Hill, Wietrznia Beds. Scale bars 1 mm.