Nannoturba joceliniae, 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 : 354

Nannoturba joceliniae n. sp.

( Fig. 19 D-F)

urn:lsid:zoobank.org:act:86C68780-D532-4C0E-9AB7-8C5749A5D19A

HOLOTYPE. — Fig. 19D ( IRSNB b7123) (negatives stored in the collections of the RBINS).

PARATYPES. — 2 figured specimens from the Mont-des-Récollets (lmax = 17.6 µm): 1 from the sample that yielded the holotype (Unit B4, sample 122.85 m) ( Fig. 20F ) ( IRSNB b7125) and 1 from the base of the Lede Sand Formation (123.50 m) ( Fig. 20E ) ( IRSNB b7124).

DIAGNOSIS. — Large, irregular network of calcite laths, joining at the centre in a central protruding x- shaped wedge.

DERIVATIO NOMINIS. — The name is a combination of the Christian names Joachim and Celine, introduced to commemorate and celebrate the wedding day of these two lovely persons.

LOCUS TYPICUS. — Mont-des-Récollets , ‘ Grande Carrière’, N France; 50°48’02.74”N, 2°30’23.06”E.

STRATUM TYPICUM. — Brussel Sand Formation, Unit B4 (sample 122.85 m); upper part of NP14.

DIMENSIONS. — Height = 16.8 to 17.6 µm; width = 15.6 to 14.6 µm (holotype: h = 16.8 µm, w = 15.2 µm).

DISTRIBUTION. — At the Mont-des-Récollects this species is consistently present from the upper part of the Brussel Sand Formation (Unit B4), and ranges through the Lede Sand Formation up to the base of the Wemmel Sand Member (upper NP14 to lower NP15). However, there are earlier records from the Oedelem borehole (13.50 m depth, middle of Oedelem Sand Member), assignable to the extreme top of NP13, and from the Mont-des-Récollets (Unit B2) and the Nederokkerzeel and Vossem outcrops (upper Unit B3 of the Brussel Sand Formation), all assignable to the lower middle part of NP 14.

DESCRIPTION

This taxon is composed of an irregular complex network of several long calcite laths (up to 7), meeting at different angles in the centre of a more or less cubic structure. The dimensions are highly variable, as the different laths are often broken off. The longest diagonal reaches up to 17.6 µm, the second is generally slightly shorter. The centre is marked by an x-shaped protruding wedge. All calcite laths are strongly birefringent in cross-polarized light.

DISCUSSION

Similar lathlike networks with central X-shaped to diamond-shaped wedges were described from upper Ypresian deposits of the southern North Sea Basin ( Steurbaut 2011). Nannoturba joceliniae n. sp. differs from all previously described Nannoturba species ( N. robusta , N. spinosa and N. jolotteana ) by a reduced number (up to 7) of long, almost completely free, irregularly distributed laths, which only meet at the centre in an x-shaped to diamond-shaped wedge. In all others taxa the laths are joined over most of their length with different configurations, according to the species ( N. robusta with quadrangular disposition and laths meeting at 90°; N. spinosa with triangular disposition with laths meeting at 120°; N. jolotteana ( Fig. 19A ) resembling a flattened octahedron, with rhombic cross-section). It differs from specimens described as Nannotetrina nitida by Aubry (1983: pl. 5, figs 13-14), as well as from the latter’s holotype (originally described as Tetralithus nitidus by Martini 1961: pl. 1, fig. 5, pl. 4, fig. 41), by its large number of different sized laths. In fact, the specimens figured by Aubry also seem to belong to the genus Nannoturba , but probably represent another new species, different from Tetralithus nitidus Martini, 1961 .

Figures

FIG. 19. — New or less known calcareous nannofossil taxa from the Eocene of the Mont-des-Récollets and other localities in Belgium. Pars 2: A, Nannoturba jolotteana Steurbaut, 2011, Mont-des-Récollets, 104.35 m, d = 15.2 µm (IRSNB b7120); B, C, Luminocanthus eolutetiensis n. gen., n. sp.; B, Vlakte van de Raan BH, 81.45 m depth, holotype, d = 9 µm (IRSNB b7121); C, Vlakte van de Raan BH, 79.95 m depth, paratype, d = 9 µm (IRSNB b7122); D-F, Nannoturba joceliniae n. sp., Mont-des-Récollets; D, 122.85 m, holotype, wm = 17 µm (IRSNB b7123); E, 123.50 m, paratype, wm = 13 µm (IRSNB b7124); F, 122.85 m, paratype, wm = 13 µm (IRSNB b7125); G-J, Luminocanthus plenilutetiensis n. gen., n. sp.; G, Mont-des-Récollets, 122.26-122.21 m, holotype, d = 8.4 µm (IRSNB b7126);H, Vossem, otolith sample Nolf 1974, paratype, d = 5.2 µm (IRSNB b7127); I, Prémontré, sample 12, paratype, d = 9.6 µm (IRSNB b7128); J, Knokke BH, 71.95 m depth, paratype, d = 6.7 µm (IRSNB b7129); K-N, Toweius brusselensis Steurbaut, 2011; K, Knokke BH, 97.50 m, paratype, d = 8.4 µm (IRSNB b6403); L, Mont-des-Récollets 122.85 m, l = 6 µm (IRSNB b7130); M, N, Vossem,otolith sample Nolf 1974, l = 4.6 µm (IRSNB b7131, b7132); O, Cribrocentrum sp. Isnes, sample 8, l = 5.9 µm (IRSNB b7133); P, Sphenolithus spiniger Bukry, 1971, Vossem,otolith sample Nolf 1974, h = 6.2 µm (IRSNB b7134); Q, Sphenolithus radians Deflandre in Grassé, 1952, Vossem, otolith sample Nolf 1974, h = 4.2 µm (IRSNB b7135); R, Sphenolithus moriformis (Bronnimann & Stradner, 1960), Vossem, otolith sample Nolf 1974, h = 3.3 µm (IRSNB b7136); S-V, Pemma spp.; S, Mont-des-Récollets, 115.50 m, d = 9 µm (IRSNB b7137); T-V, Vossem, otolith sample Nolf 1974 (IRSNB b7138, b7139, b7140); T, d = 8.3 µm; U, d = 8.4 µm; V, d = 6.5 µm.

FIG. 20. — New or less known calcareous nannofossil taxa from the Eocene of the Mont-des-Récollets and other localities in Belgium.Pars 3: A-G, Blackites praeinflatus n. sp.; A, Mont-des-Récollets, 122.26-122.21 m, holotype, l = 23.0 µm (IRSNB b7141); B, paratype, Mont-des-Récollets, 122.16 m, paratype, l = 22.5 µm (IRSNB b7142); C, Mont-des-Récollets, 122.26-122.21 m, paratype, l = 24.0 µm (IRSNB b7143); D, Zaventem, sample 17, paratype, l = 24.0 µm (IRSNB b7144); E, Mont-des-Récollets,122.26-122.21 m, paratype,l = 29.0 µm (IRSNB b7145); F, G, Vossem, otolith sample Nolf, 1974, paratypes (IRSNB b7146, b7147); F, l = 23.05 µm; G, l = 15.2 µm;H-K, Blackites inflatus (Bramlette & Sullivan, 1961);H, Isnes,sample 8, l = 17.5 µm (IRSNB b7148);I, Gobertange,sample Go5, l = 28 µm (IRSNB b7149); J, Isnes, sample 8, l = 18 µm (IRSNB b7150); K, Gobertange, sample Go5, l = 26 µm (IRSNB b7151); L-M, Blackites aff. gladius (Locker, 1967), Isnes, sample 8 (IRSNB b7152, b7153); L, l = 10.46 µm; M, l = 11.76 µm; N-Q, Sphenolithus quadricornutus n. sp.; N, Mont-des-Récollets, 126.50 m, holotype, htot = 9 µm, hpc = hle = 2 µm (IRSNB b7154); O, Balegem, level 6, paratype, hpc + hle = 4 µm (IRSNB b7155); P, Mont-des-Récollets 126.50 m, paratype,htot = 6 µm, hpp + hle = 3 µm (IRSNB b7156); Q, Mont-des-Récollets, 122.85 m, paratype, htot = 9 µm, hpc + hle = 3 µm (IRSNB b7157); R, Sphenolithus perpendicularis Shamrock, 2010, Balegem, level 6, h = 5 µm (IRSNB b7158); S, Trochastrites hohnensis (Martini, 1958). Mont-des-Récollets, 122.85 m, wm = 12 µm (IRSNB b7159); T-W, Trochastrites pyramidalis n. sp.; T, Oedelem BH, 5.50 m, paratype, wm = 10 µm (IRSNB b7160); U, Mont-des-Récollets,122.16 m, holotype, wm = 12 µm (IRSNB b7161); V, Oedelem BH,5.50 m, paratype,wm = 13 µm (IRSNB b7162); W, Vlakte van de Raan BH,80.27 m, paratype, wm = 12 µm (IRSNB b7163).