Prophyllodictya khrevitsa, Tolokonnikova & Fedorov, 2023

Tolokonnikova, Zoya A. & Fedorov, Petr V., 2023, Morphological features of Late Ordovician (Sandbian) bryozoans from the basin of Khrevitsa River (north-western Russia) and description of a new species of the genus Prophyllodictya Gorjunova, 1987, Zootaxa 5284 (2), pp. 337-350 : 340-341

Prophyllodictya khrevitsa n. sp.

( Fig. 3 , Table 1 )

Holotype. CNIGR museum № 13/13403; surroundings of Khrevitsa village , Khrevitsa Formation, Ordovician (Sandbian); Leningrad region, Russia.

Additional material. CNIGR museum № 14/13403, 15/13403, 16/13403, 17/13403, 18/13403, 19/13403; same details as for the holotype .

Etymology. Named after the Khrevitsa Formation from which the specimens were collected. It is used as a name in apposition.

Diagnosis. Colony reticulate with branches lens-shaped in transversal section. Mesotheca slightly sinuous. Rare diaphragms. Autozooecial apertures arranged in regular diagonal rows. Paurostyles in a single row between autozooecial apertures.

Description. Colony bifoliate, reticulate. Branches lens-shaped in transversal section. Mesotheca slightly sinuous, lacking hyaline rods, 0.02 mm in thickness. Endozone is narrow. One or two diaphragms in autozooecial chambers. Autozooecia long, tubular, sharply bending near proximal end. Extrazooecial skeleton developed, distinctly lamellar.Autozooecial apertures on branch surfaces oval or subcircular, arranged in regular diagonal rows. Apertural interspaces and marginal area of branches ridged, occupied by paurostyles. Paurostyles usually arranged in a single row between autozooecial apertures and in gatherings on branch margins.

Comparison. Prophyllodictya khrevitsa n. sp. differs from P. putilovensis Lavrentjeva, 1993 (in Gorjunova & Lavrentjeva 1993) from the Dapingian-lower Darriwilian of Leningrad region in having narrower colonies (0.75–1.75 mm vs 3.00– 3.50 mm in P. putilovensis ), regular arrangement of smaller paurostyles (0.01–0.02 mm vs confined location and 0.04–0.06 mm in P. putilovensis ), and smaller apertures (0.06–0.08 x 0.14–0.18 mm vs 0.17–0.20 x 0.26–0.31 mm in P. putilovensis ).

Stratigraphical and geographical ranges. Khrevitsa Formation, Ordovician (Sandbian); Leningrad region, Russia.

Figures

FIGURE 3. Prophyllodictya khrevitsa n. sp. from the Khrevitsa Formation. A_D. CNIGR museum № 13/13403. A. Colony exterior with transverse section of the branch (micro-CT). B. Tangential section (micro-CT). C. Colony exterior (micro-CT). D. Longitudinal section. E. №16/13403, transverse section showing mesotheca and lens-shaped form of branch. F. №14/13403, tangential section before ramification. G. №15/13403, transverse section showing mesotheca (arrow).