Martiniaster cecellanoriae, Steurbaut, Etienne & Nolf, Dirk, 2021

Steurbaut, Etienne & Nolf, Dirk, 2021, The Mont-des-Récollets section (N France): a key site for the Ypresian-Lutetian transition at mid-latitudes - reassessment of the boundary criterion for the base- Lutetian GSSP, Geodiversitas 43 (11), pp. 311-363 : 346

Martiniaster cecellanoriae n. sp.

( Fig. 18F, G )

urn:lsid:zoobank.org:act:BC34435D-E488-4BDF-A956-093AA0FA4C44

Martiniaster fragilis – Aubry 1983: 156, pl. 4, fig. 23; 1986: 327, pl. 4, fig. 23 (non C. fragilis Martini, 1961 ).

HOLOTYPE. — Fig. 18G ( IRSNB b7099) (negative stored in the collections of the RBINS).

PARATYPES. — 1 from the “Chaumont-en-Vexin sands” at Chaumonten-Vexin (sample CHA 11, 0.55 m above the base of the Lutetian ( Fig. 18F , IRSNB b7098) and 2 non-figured specimens from the base of Unit A4 of the Aalter Sand Formation (Mont-des-Récollets: 114.85 m and Vlakte van de Raan borehole: 82.95 m depth).

DIAGNOSIS. — Circular fragile structure, slightly conical in side view, consisting of a series of concentric rings, supported by 17 to 19 radially oriented pillars, resembling a spider’s web.

DERIVATIO NOMINIS. — The species name is a combination of Cecile, the Christian name of the first author’s spouse, who passed away recently, and of Ella-Noor, the first name of his grand-daughter.

LOCUS TYPICUS. — Leuven borehole, 23.70 m depth, 50°53’24.36”N, 4°42’33.69”E.

STRATUM TYPICUM. — Brussel Sand Formation, base of Unit BE; base of NP14.

DIMENSIONS. — Diameter = 13 to 14 µm (holotype: d = 14 µm).

DISTRIBUTION. — At the Mont-des-Récollets it is known from 1 specimen in the upper part of the Aalter Sand Sand Formation (lower Unit A4, base NP14). It has also been recorded in the Vlakte van de Raan borehole at the top of the Aalter Sand Formation (upper Unit A4, 82.95 m depth, lower NP14) and in the Leuven-Artois borehole (base of Unit BE, base of NP14). It has been identified in several samples of the lower part of the ‘Chaumon-en-Vexin sands’ at the Darcy site at Chaumont-en-Vexin (Steurbaut, unpublished information). These records led us to conclude that the LO of M. cecellanoriae n. sp. is a major stratigraphical marker, as it is coincident with the base of NP14 and the base of the historical Lutetian stratotype.

DESCRIPTION

This circular slightly inflated body consists of a number of (generally three) peripheral concentric rings surrounding a central network, which are supported by 17 to 19 radially oriented pillars. This concentric structure, which resembles a spider’s web, shows no birefringence under crossed nicols.

DISCUSSION

This taxon has many similarities with Martiniaster fragilis , but instead of the 12 radially arranged peripheral ridges, it has a much larger number of radial pillars (generally between 17 and 19), which are less prominently developed. It appears to be also less globular.

Figures

FIG. 18. — New or less known calcareous nannofossil taxa from the Eocene of the Mont-des-Récollets and other localities in Belgium;a, b, c, views of the same specimen, in transmitted light or cross-polarized light or vice versa, and in different positions with respect to the polarisation directions. Numbers (e.g. IRSNB bXXXX) refer to the collections of the Royal Belgian Institute of Natural Sciences (Brussels).Pars 1: A-D, Braarudosphaera stylifera Troelsen & Quadros,1971,Mont-des-Récollets,122.85 m (IRSNB b7093,b7094,b7096);A, wm = 13 µm;B, wm = 12 µm;D, wm = 14.5 µm;C, Mont-des-Récollets,124.10 m (IRSNB b7095),wm = 13 µm;E, Lanternithus minutus Stradner, 1962, Mont-des-Récollets, 122.85 m, l = 5.6 µm (IRSNB b7097); F, G, Martiniaster cecellanoriae n. sp.: F, Chaumont-en-Vexin, sample 11, 0.55 m above base of the Lutetian, paratype,d = 13 µm (IRSNB b7098);G, Leuven BH,23.70 m depth, holotype,d = 14 µm (IRSNB b7099);H, Discoaster praebifax Wei & Wise,1989, Mont-des-Récollets,116.45 m, d = 7 µm (IRSNB b7100);I-M, Discoaster sublodoensis Bramlette & Sullivan,1961,Mont-des-Récollets,116.45 m (IRSNB b7101,b7102); J, d = 15.2 µm; I, d = 16 µm; K, Mont-des-Récollets, 118.35 m, d = 11.6 µm (IRSNB b7103); L, Vossem, otolith sample Nolf 1974, d = 7 µm (IRSNB b7104); M, Gisors, Bassin de Paris,sample 3,d = 14 µm (IRSNB b7105);N, Martiniaster fragilis (Martini,1961), Mont-des-Récollets,122.85 m, wm = 12 µm (IRSNB b7106);O-R, Discoaster wemmelensis Achuthan & Stradner,1969;O, Mont-des-Récollets, 122.85 m, d = 5.6 µm (IRSNB b7107); P-R, Vossem,otolith sample Nolf 1974 (IRSNB b7108, b7109, b7110);P, d = 5.3 µm; Q, d = 4.4 µm; R, d = 4.3 µm;S-V, Blackites minusculus n. sp.; S, Mont-des-Récollets,117.46 m, paratype, l = 8.8 µm (IRSNB b7111); T-V, Vossem, otolith sample Nolf 1974; T, U, paratypes (IRSNB b7112, b7113); T, I = 8.2 µm;U, I = 7.2 µm;V, holotype,I = 8.56 µm (IRSNB b7114); W-Y, Trochoaster nodosus n. sp.; W, Chaumont-en-Vexin,sample 16, 0.80 m above base of the Lutetian,holotype, d = 16 µm (IRSNB b7115);X, Vilvoorde BH, 5.80 m depth,paratype,d = 15 µm (IRSNB b7116); Y, Oedelem BH, 11.70 m depth, paratype, d = 15 µm (IRSNB b7117); Z-AA, Sphenolithus recolletensis n. sp.; Z, Mont-des-Récollets, 116.45 m, paratype, htot = 20 µm (IRSNB b7118);AA, Mont-des-Récollets, 117.46 m, holotype (a, c, parallel to the polarization directions;b, at 45°), htot = 11.4 µm (IRSNB b7119).