Penniretepora d’Orbigny, 1849

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 : 194-196

Genus Penniretepora d’Orbigny, 1849

Acanthopora Young & Young, 1875: 327 .

Pinnatopora Vine, 1883: 191 .

TYPE SPECIES. — Retepora pluma Phillips, 1836 . Mississippian ; Yorkshire, England.

DIAGNOSIS. — Fine main branch and short, regularly arranged secondary branches without dissepiments. Two rows of autozooecia on the main branch and on the secondary branches.

OCCURRENCE. — Devonian to Permian; worldwide.

Penniretepora volgensis Shishova, 1959 ( Figs 28G, H ; 29 A-D; Appendix)

Penniretepora volgensis Shishova, 1959: 17 , fig. 1.

MATERIAL. — SMF 21.961- SMF 21.964.

OCCURRENCE. — Carboniferous, Mississippian (Visean); Russia. Carboniferous, Mississippian (upper Visean); Roque Redonde (Montagne Noire, southern France).

DESCRIPTION

Pinnate colonies consisting of straight main branches with frequent lateral branches. Main branches 0.38-0.70mm wide, lateral branches 0.18-0.38 mm wide, diverging at angles 60- 84° from main branches, spaced 0.72-1.05 mm from centre to centre. Autozooecia having circular to oval apertures, arranged in two rows both on main and lateral branches; two to three apertures between two neighbouring lateral branches. Median keels low, containing rare elliptical nodes.

INTERNAL DESCRIPTION

Autozooecial chambers rectangular to pentagonal in mid tangential section both on main and secondary branches, relatively long, inflated, with moderately long vestibules. Superior hemisepta short; inferior hemisepta absent. Axial wall straight to weakly undulating from base to crest, projecting as narrow and low frontal keel. Extrazooecial skeleton moderately developed, traversed by abundant microstyles; microstyles diverging from inner hyaline skeleton, regularly spaced across entire colony surface, 0.010 -0.018 mm in diameter. Reverse side containing longitudinal rows of microstylets.

COMPARISON

Penniretepora volgensis Shishova, 1959 differs from P. timofeevae Balakin, 1975 from the lower Visean of Turkmenistan in larger distances between lateral branches (0.72-1.05 mm vs 0.50-0.75 mm in P. timofeevae ).

Penniretepora cf. pluma ( Phillips, 1836) ( Figs 29 E-I; 30A; Appendix)

MATERIAL. — SMF 21.965- SMF 21.966.

OCCURRENCE. — Carboniferous, Mississippian, Visean; Britain, Ireland, Roque Redonde (Montagne Noire, southern France).

DESCRIPTION

Pinnate colonies consisting of straight main branches with frequent lateral branches. Main branches 1.00- 1.05mm wide, lateral branches 0.52-0.60 mm wide, diverging at angles 57- 80° from main branches, spaced 0.72-1.05 mm from centre to centre. Autozooecia having circular to oval apertures, arranged in two rows both on main and lateral branches; apertures surrounded by 14-16 apertural nodes, producing faintly denticulated margin two-three apertures between two neighbouring lateral branches. Median keel low, containing rare elliptical nodes and longitudinal rows of microstyles.

INTERNAL DESCRIPTION

Autozooecial chambers rectangular to pentagonal in mid tangential section both on main and secondary branches, relatively long, inflated, with moderately long vestibules. Superior hemisepta short; inferior hemisepta absent. Axial wall straight to weakly undulating from base to crest, projecting as narrow and low frontal keel. Extrazooecial skeleton moderately developed, traversed by abundant microstyles; microstyles diverging from inner hyaline skeleton, regularly spaced across entire colony surface, 0.010 -0.018 mm in diameter. Reverse side containing longitudinal rows of fine tubules.

COMPARISON

This species is characterised by circular to oval apertures, surrounded by small apertural nodes, and which are proximally extended into a small slit or fossula. As such it broadly resembles P. pluma , but differs from it in the rectangular to pentagonal shape of autozooecial chambers and the closer spacing of apertures.

Figures

FIG. 28. — A, B, Baculopora redondensis n. sp.; A, branch transverse section, paratype SMF 21.939; B, branch oblique section showing autozooecial chambers, paratype SMF 21.941; C-F, Filites cf. laxa (Young & Young,1876),tangential to mid-tangential section showing autozooecial chambers and apertures,SMF 21.956; G, H, Penniretepora volgensis Shishova, 1959,SMF 21.964; G, tangential section showing the reverse branch side; H, I, tangential section showing autozooecial apertures and median keel. Scale bars: A, B, D-F, 0.5 mm; C, 2 mm; G-I, 1mm.

FIG. 29.— A-D, Penniretepora volgensis Shishova,1959;A, tangential section showing the reverse branch side,SMF 21.964; B, C, mid-tangential section showing autozooecial chambers, SMF 21.962; D, branch oblique section showing autozooecial chambers, SMF 21.961; E-I, Penniretepora cf. pluma (Phillips, 1836); E, mid-tangential section showing autozooecial chambers, SMF 21.965; F, tangential section showing autozooecial apertures, SMF 21.966; G, mid-tangential section showing autozooecial chambers, SMF 21.965; H, I, tangential section showing autozooecial apertures with nodes and median keel, SMF 21.966. Scale bars: A, C, D, I, 0.2 mm; B, G, H, 0.5 mm; E, 2 mm; F, 1 mm.