Gorjunopora gallica, Ernst & Wyse Jackson & Aretz, 2015

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 : 196-198

Gorjunopora gallica n. gen., n. sp.

( Fig. 30 B-I; Appendix)

ETYMOLOGY. — The species name refers to the discovery of this species in France.

HOLOTYPE. — SMF 21.967 .

PARATYPES. — SMF 21.968- SMF 21.972.

TYPE LOCALITY. — Roque Redonde (Montagne Noire,southern France).

TYPE HORIZON. — Carboniferous, Mississippian (upper Visean).

DIAGNOSIS. — As for genus.

DESCRIPTION

Pinnate colonies consisting of straight main branches with frequent lateral branches. Main branches 0.22-0.36mm wide, lateral branches 0.14-0.22 mm wide, diverging at angles 57- 81° from main branches, spaced 0.69-1.05 mm from centre to centre. Autozooecia having circular to oval apertures, arranged in two rows both on main and lateral branches; one aperture between two neighbouring lateral branches. Median keels low, containing alternating elliptical nodes.

INTERNAL DESCRIPTION

Autozooecial chambers triangular to trapezoid in mid tangential section both on main and secondary branches, relatively long, inflated, with moderately long vestibules. Superior hemisepta long, proximally curved; internal curved hemisepta in middle part of chambers present. Axial wall strongly zigzag from base to crest, projecting as narrow and low frontal keel. One row of weakly alternating and closely spaced nodes on keel present.Extrazooecial skeleton moderately developed, traversed by abundant microstyles; microstyles diverging from inner hyaline skeleton, regularly spaced across entire colony surface, 0.010 -0.015 mm in diameter. Reverse side showing fine longitudinal striation.

COMPARISON

Gorjunopora gallica n. gen., n. sp. is similar to G. triangulata (Schulga-Nesterenko, 1955) from the Visean of the Russian Platform. Gorjunopora gallica differs in having larger distances between aperture centres (averagely 0.38 mm vs 0.28 mm in G. triangulata ) and spacing of one aperture between neighbouring lateral branches instead of two apertures in G. triangulata .

Incertae Sedis

“ Thamniscus ” colei Wyse Jackson, 1988 ( Fig. 31 A-D; Appendix)

Thamniscus colei Wyse Jackson, 1988: 205 , figs 1c, 2c, 4g-j, 7c-f; 1996: 143, fig. 48. — Wyse Jackson & Bancroft 1994: 215-7, fig. 1a-f. — Wyse Jackson & Weber 2005: 377, fig. 1k.

MATERIAL. — SMF 21.973,TCD.60356.

OCCURRENCE. — Carboniferous, Mississippian (Visean); Ireland, Germany (Velbert Anticline, Rhenish Massif), Roque Redonde (Montagne Noire, southern France).

DESCRIPTION

Freely branching, dichotomous colonies. Branches 0.54- 0.74 mm wide. Autozooecia arranged in 2-3 rows on branches, pentagonal to hexagonal in mid tangential section.Autozooecial apertures circular, with smooth peristomes. Single node on proximal part of peristomes present, mm in diameter. Fine striation between apertures developed.

COMPARISON

The genus Thamniscus King, 1849 is apparently monotypical, with the type species Thamniscus perplexus Ernst in Lisitsyn & Ernst, 2004 which is only known from the Upper Permian Zechstein of Europe ( Lisitsyn & Ernst 2004; Wyse Jackson et al. 2006). Many species were placed in the genus on the basis of the freely branching colony form, having various internal morphology. “ Thamniscus ” colei Wyse Jackson, 1988 differs from the type species in having pentagonal to hexagonal shape of autozooecial chambers in mid tangential section instead of rhombic one in T. perplexus , and in the absence of cyclozooecia. “ Thamniscus ” colei should be classified in a separate genus. However, the material from Roque Redonde is represented by only one fragment which is not sufficient to erect a new genus here.

Fenestrata sp. ( Figs 31 E-I; Appendix)

MATERIAL. — Single specimen SMF 21.974.

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

DESCRIPTION

Colony shape unknown, apparently pinnate to loosely branching with occasional transverse connections. Branch width 1.02- 1.20 mm. Autozooecia arranged in two rows on branches, triangular to trapezoid in mid tangential section. Autozooecial aperture circular, surrounded by a rim of 10-14 nodes. Apertural nodes 0.010 -0.025 mm in diameter. Median keel low, undulating, containing large elliptic and widely spaced nodes. External skeleton 0.29-0.43 mm thick, laminated, traversed by abundant microstylets. Internal skeleton granular, 0.055 -0.065 mm thick.

COMPARISON

Comparison of this species is difficult because of restricted material. It shows similarities to Narynella Morozova, 2001 in the shape of autozooecia and presence of keel with large and widely spaced nodes. However, Narynella has typical reticulate colony shape and weakly developed external laminated skeleton.

Figures

FIG. 30. — A, Penniretepora cf. pluma (Phillips, 1836), tangential section showing the reverse branch side, SMF 21.966; B-I. Gorjunopora gallica n. gen., n. sp.; B, C, tangential section, holotype SMF 21.967; D-F, mid-tangential section showing autozooecial chambers with hemisepta (arrow), holotype SMF 21.967; G, tangential section showing nodes (arrow), paratype SMF 21.970; H, I, tangential section showing autozooecia chambers and apertures, paratype SMF 21.972. Scale bars: A, D, G, I, 0.2 mm; B, 2 mm; C, H, 0.5 mm; E, F, 0.1 mm.

FIG. 31. — A-D, “Thamniscus” colei Wyse Jackson,1988,tangential section showing autozooecial apertures and branch surface,SMF 21.973; E-I, Fenestrata sp., SMF 21.974; E, H, I, tangential section showing autozooecial apertures and nodes (arrows); F, G, mid-tangential section showing autozooecial chambers and external laminated skeleton. Scale bars: A, E, F, 2 mm; B-D, G, H, 1mm; I, 0.2 mm.