Nematopora Ulrich, 1888

Ernst, Andrej, Wyse Jackson, Patrick N. & Aretz, Markus, 2015, Bryozoan fauna from the Mississippian (Visean) of Roque Redonde (Montagne Noire, southern France), Geodiversitas 37 (2), pp. 151-213 : 174

Genus Nematopora Ulrich, 1888

TYPE SPECIES. — Trematopora minuta Hall, 1876 by original designation. Silurian of Indiana ; USA.

OCCURRENCE. — Middle Ordovician to Permian; worldwide.

DIAGNOSIS. — Delicate, erect dichotomously branching colonies, composed of straight branches, sub-circular to circular in crosssection; axial region consisting of well defined medial axis, planar medial wall developed locally in some species; autozooecia tubular, triangular in cross section in endozone, inflated on their bases, diverging from the medial axis, bending abruptly in exozone, having a length of 4-6 times their diameter; rare diaphragms can appear; autozooecial apertures oval or rounded, dorsally flared, arranged regularly in 4 to 10 longitudinal rows, commonly having peristomes; zooecial boundaries well defined, narrow; extrazooecial skeleton well developed; paurostyles common on ridges in many species; nodes rarely occur. Heterozooecia absent.

COMPARISON

Genus Nematopora Ulrich, 1888 differs from Ulrichostylus Bassler, 1952 by the shape of autozooecia which bend in exozone.

Nematopora hibernica Wyse Jackson, 1996 ( Fig. 17 B-D; Appendix)

Nematopora hibernica Wyse Jackson, 1996: 124 , figs 3b, 6, 7.

MATERIAL. — TCD.60334, 60337, 60342, 60348, 60349.

OCCURRENCE. — Mississippian, Visean; Ireland ( Wyse Jackson, 1996), Roque Redonde (Montagne Noire, southern France).

DESCRIPTION

Delicate colonies comprising dichotomising branches; crosssectional shape circular to polygonal. Autozooecia arranged in five rows on obverse surface. Interapertural walls undulatory between autozooecia in longitudinal rows, smooth with small stylets along their crests. Autozooecial apertures pyriform, twice as long as wide. Reverse surface barren, smooth with faint longitudinal rows of small stylets. Autozooecial chambers vermiform, elongate in tangential section, six times long as wide, developed from sinuous central axis; slight deviation towards outer margin at exozone; exozone wall of coarsely granular skeleton.

COMPARISON

Nematopora hibernica is one of eight species in the genus described from Carboniferous successions worldwide ( Wyse Jackson, 1996, Appendix 4), and differs from them in having fewer rows of autozooecia.

Figures

FIG. 17. — A, Dyscritella sp., longitudinal section,TCD.60345;B-D, Nematopora hibernica Wyse Jackson,1996;B, obverse colony surface,TCD.60348;C, obverse colony surface, TCD.60349; D, reverse colony surface, TCD.60349. Scale bars: A, 0.5 mm; B-D, 1 mm.