Rectifenestella exiliformis, Ernst & Fernández & Fernández-Martínez & Vera, 2012

Ernst, Andrej, Fernández, Luis Pedro, Fernández-Martínez, Esperanza & Vera, Carmen, 2012, Description of a bryozoan fauna from mud mounds of the Lebanza Formation (Lower Devonian) in the Arauz area (Pisuerga-Carrión Province, Cantabrian Zone, NW Spain), Geodiversitas 34 (4), pp. 693-738 : 720-724

publication ID

https://doi.org/ 10.5252/g2012n4a1

persistent identifier

https://treatment.plazi.org/id/03A6D074-FFF4-7E0C-FCEB-FCD6FCC3FD30

treatment provided by

Marcus

scientific name

Rectifenestella exiliformis
status

sp. nov.

Rectifenestella exiliformis n. sp. ( Figs 17 View FIG A-I; 18A-C; Appendix)

HOLOTYPE. — SMF 21.314 About SMF .

PARATYPES. — SMF 21.315- SMF 21.332.

ETYMOLOGY. — The species name refers to the similarity with the species R. exilis (Počta, 1894) from the Lower Devonian (Pragian) of Czech Republic.

TYPE LOCALITY. — Arauz Sur (Arroyo section), Province of Palencia, NW-Spain (Cantabrian Mountains).

TYPE HORIZON. — Lebanza Formation, Lower Devonian (Pragian).

DIAGNOSIS. — Reticulate colonies with straight branches joined by moderately wide dissepiments; autozooecia pentagonal in mid tangential section, arranged in 2 alternating rows on branches, with an additional row shortly before bifurcations, 4-7 spaced per length of a fenestrule; axial wall zigzag; peristomes containing 10-15 variously sized nodes, with 3-6 larger than the others; fenestrules oval to rectangular; keels wide, low, with widely spaced, stellate nodes; microacanthostyles abundant; large styles present on the reverse colony surface.

DESCRIPTION

Reticulate colonies with straight branches, bifurcating, joined by dissepiments. Autozooecia arranged in 2 alternating rows on branches, with additional row shortly before bifurcation, having circular apertures with moderately high peristomes, 4-7 spaced per length of a fenestrule. Peristomes containing 10-15 variously sized nodes, of which 3-6 are significantly larger than the others. Smaller nodes 0.010 -0.015 mm in diameter, larger nodes 0.020 -0.030 mm in diameter. Fenestrules oval to rectangular. Median keel wide, low. Keel nodes widely spaced, granular core stellate in shape. Microacanthostyles on the colony surface abundant, regularly spaced in longitudinal rows, 0.01-0.02mm in diameter. Large styles irregularly spaced on the reverse colony surface, 0.03-0.06 mm in diameter.

Interior description

Autozooecia pentagonal in mid tangential section; with well-developed long vestibule; axial wall zigzag; aperture positioned at distal end of chamber. Autozooecial chambers diverging laterally at angles of 42-70°. Superior hemisepta indistinct; inferior hemisepta absent. Internal granular skeleton continuous with obverse keel, nodes, peristome and across dissepiments, 0.020 -0.045 mm thick on the branch reverse wall. Outer lamellar skeleton well developed, 0.015 -0.060 mm thick on the branch reverse wall. Terminal diaphragms common.

COMPARISON

Rectifenestella exiliformis n. sp. is similar to R. exilis (Počta, 1894) View in CoL from the Lower Devonian (Pragian) of Czech Republic, but differs in having thicker branches (average branch width 0.31 mm vs 0.21 mm in R.exilis View in CoL ), more closely spaced autozooecial apertures (average distance between aperture centres 0.18 mm vs 0.23 mm in R. exilis View in CoL ), and more widely spaced branches and dissepiments. Furthermore, R. exilis (Počta, 1894) View in CoL has a row of small nodes on the keel instead of the large stellate nodes seen in R. exiliformis . Fenestella View in CoL aff. parallela Hall, 1881 described by Ernst et al. (2011: 318-320, figs 8e-g, 9a-d) has a similar peristome morphology with variously sized nodes and stellate nodes on the median keel. However, this species has rectangular shaped autozooecia in mid tangential section and a smaller number of autozooecia per fenestrule (2-4 in Fenestella View in CoL aff. parallela vs 4-7 in R. exiliformis ). Fenestella (Rectifenestella) asterogrumosa Waschurova, 1964 from the Lower Devonian (?Emsian) of Tajikistan has a similar peristome morphology, stellate nodes on the keel and pentagonal shaped autozooecia in mid tangential section. However, this species lacks styles on the reverse surface and has 2-3 autozooecia per fenestrule length instead of 4-7 in R.exiliformis . Waschurova (1964: 80) mentioned 7-20 apertural nodes 0.005 -0.015 mm in diameter,without stressing variation in size. Figure 1 View FIG on Waschurova’s plate 27 shows some significantly larger nodes in the aperture, however.

The present material is placed in Rectifenestella Morozova, 1974 View in CoL because of the autozooecial chamber shape and character of the meshwork. However, the morphology of the peristome with variously sized nodes is quite unusual for Rectifenestella View in CoL , which usually has stellate structures consisting of 8 rays in the apertures.

SMF

Forschungsinstitut und Natur-Museum Senckenberg

Kingdom

Animalia

Phylum

Bryozoa

Class

Stenolaemata

Order

Fenestrida

Family

Fenestellidae

Genus

Rectifenestella

Loc

Rectifenestella exiliformis

Ernst, Andrej, Fernández, Luis Pedro, Fernández-Martínez, Esperanza & Vera, Carmen 2012
2012
Loc

Rectifenestella exiliformis

Ernst & Fernández & Fernández-Martínez & Vera 2012
2012
Loc

R. exiliformis

Ernst & Fernández & Fernández-Martínez & Vera 2012
2012
Loc

R. exiliformis

Ernst & Fernández & Fernández-Martínez & Vera 2012
2012
Loc

R.exiliformis

Ernst & Fernández & Fernández-Martínez & Vera 2012
2012
Loc

Rectifenestella

Morozova 1974
1974
Loc

Rectifenestella

Morozova 1974
1974
Loc

Fenestella (Rectifenestella) asterogrumosa

Waschurova 1964
1964
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