Elphidiella falunica (Allix, 1913)

Margerel, Jean-Pierre & Poignant, Armelle, 2018, Two poorly known species of Foraminifera: Polystomella minuta Reuss, 1865 from the Oligocene of Germany (Bavaria) and P. falunica Allix, 1913 from the Miocene of western France (Touraine). Designation of a neotype for P. falunica, Geodiversitas 40 (19), pp. 497-504 : 500-503

Elphidiella falunica (Allix, 1913)

( Fig. 2 B-F)

DIMENSIONS. — Length = 0.560 mm; width = 0.420 mm; thickness = 0.250 mm.

TYPE LEVEL. — Langhian-Early Serravallian.

TYPE LOCALITY. — France. Loir-et-Cher, Thenay, Quarry les Gandes, 46.629°N, 1.431°E (shore sands rich in remains of shells).

EXAMINED MATERIAL. — Sample Thenay (quarry les Gandes) (reference MNHN.F.763117).

DESCRIPTION

Test round, inflated, hyaline, very smooth, bright, very finely perforated, periphery not lobate, or very little on the last chambers, not carinate, 10 chambers, flat umbilicus, sutures forming sometimes a small depression between the last chambers, underlined by small pores in one line open into subsutural canals; apertural side oval; aperture and foramina interiomarginal, multiple, masked by conical to rounded pustules.

The internal structure of the genus Elphidiella has been described by Kristoffersen (1973) and Hansen & Lykke- Andersen (1976). The description of Elphidiella minuta , i.e., falunica , given by Kristoffersenis as follows:“One row of sutural pores communicate with subsutural canal. Spiral canal forming a simple and rather regular spiral without complicated anastomoses. Retral processes not present”.

Our own observations reveal that in a majority of specimens the spire consists of two and half to three whorls and that the septal wall is bilamellar. We easily observe the sutural pores communicating with the sutural canal ( Fig. 3M, N ).

MORPHOLOGICAL VARIABILITY

Examined material

Touraine (Pontlevoy, le Piziou, le Mincé, les Gandes, la Rangère, Château Gabillon, Savigné-sur-Lathan); Anjou (Chemillé); Poitou (Mirebeau); Aquitaine (Saucats), Saint-Selve, Étang des Charmes (southern Saint-Selve), Saubrigues, Sallespisse, Baudignan, Lafaurie); Provence (Carry-le-Rouet).

The variability concerns the general shape, the number of chambers and the type of pustules situated at the base of the aperture. It is illustrated in the following figures whose specimens are deposited in the MNHN collection:

Thenay quarry les Gandes (MNHN.F.763117) ( Fig. 2 B-E);

Thenay quarry le-Piziou (MNHN.F.763118) ( Fig. 2 F-H);

Thenay quarry la Rangère (MNHN.F.763119) ( Fig. 2I, J );

Chemillé (MNHN.F.763120) ( Fig. 2K, L );

Mirebeau (MNHN.F. 763121) ( Fig. 2M, N );

Noyant (MNHN.F.763122) ( Fig. 2O, P );

Saucats (MNHN.F.763123) ( Fig. 3A, B );

Sallespisse (MNHN.F.763124) ( Fig. 3C, D );

Saint-Selve (MNHN.F.763125) ( Fig. 3E, F );

Étang des Charmes (MNHN.F.763126) ( Fig. 3G, H );

and Carry-le-Rouet (MNHN.F.763127) ( Fig. 3 I-L).

A lot of 120 specimens (MNHN.F.763128 and MNHN.F.763129) from “Bassin de Thenay” in Loir-et-Cher have been measured and the number of chambers counted. The results of the measures areas follows:

Vertical diameter: 400 to 600 µm;

Horizontal diameter: 310 to 580 µm;

Thickness: 150 to 220 µm;

Number of chambers: 9 to 11.

STRATIGRAPHICAL DISTRIBUTION

Miocene of middlewestern ( Touraine ) and southwestern France (Aquitaine) ; south France: Miocene of the Carry-le- Rouet section (Provence) ; Elphidium minutum is mentioned in the paper ( Anglada 1972) and said to be abundant in the “ Formation récifale du Cap des Nautes (Provence)” ; one specimen was deposited in the MNHN collection ; Pliocene of Anjou .

Sztrakos (1979) observed it in the Oligocene of Hungary, he only gave a drawing, but it seems to belong to the Allix species. In the same way, Cicha et al. (1998) believed it begins in the upper Kiscellian (Rupelian) but their illustration concerns the Eggenburgian. This species appears earlier in the Paratethys than in western Europe.

GEOGRAPHICAL DISTRIBUTION

Western and Central Europe (see former text): France, Belgique, Denmark, Germany, Austria, Hungary; Asia: Eastern Turkey ( Poisson et al. 1997, 2014).

GENERIC ATTRIBUTION

It is neither an Elphidium , which generally shows ponticuli across the sutures nor a Cribrononion which possesses a chamberlet at the base covered by granulations and disappearing when the following chamber appears.

Kristoffersen (1973) is hesitating as far as the generic attribution is concerned, he writes: “[…] the reference of the species to Elphidiella is debatable. Thus the double row of sutural pores which should characterize this genus are not present. When the species nevertheless is placed in the genus Elphidiella it is due to a superficial resemblance with the type species Elphidiella arctica (Parker and Jones 1864) and especially to the striking resemblance with E. hannai (Cushman and Grant 1927) and to the fact that it does not fit into any of the remaining genera available”. The specimen of Elphidiella hannai from Plio-Pleistocene deposits from Cotentin ( France) observed by Margerel possesses on the last chambers single rows of sutural pores ( Fig. 3O, P ).

We note that Loeblich & Tappan (1987) admit one row of sutural pores in Elphidiella .

CONCLUSION

Even though we have no knowledge of the Reuss type of Polystomella . minuta , we are convinced that P. minuta and P. falunica are two different species; indeed the description and figure of Reuss species are quite different from those of P. falunica . Therefore, the problem remains, what is really Polystomella minuta? We conclude that the now well known Polystomella falunica , needs to be used instead of P. minuta specially in the Miocene where it is frequent.

Figures

FIG. 2. — A, Polystomella falunica Allix, 1913; B-P, Elphidiella falunica (Allix, 1913), Thenay (les Gandes); B, C, lateral and oral views; D, sutural pores; F-H, Thenay (le Piziou); A, B, lateral and oral views; C, enlargement of the oral part; I, J, Thenay (la Rangère), lateral and oral views; K, L, Chemillé, lateral and oral views; M, N, Mirebeau, lateral and oral views; O, P, Noyant, lateral and oral views. Scale bars: A-C, I-P, 200 mm; F, G, 100 mm; H, 50 mm; D, 20 mm; E, 5 mm.

FIG. 3. — A-N, Elphidiella falunica (Allix, 1913); A, B, Saucats; C, D, Sallespisse; E, F, Saint-Selve; G, H, Étang des Charmes; I-L, Carry-le-Rouet, lateral and oral views; M, sutural canal; N, section; O, P, Elphidiella hannai (Cushman & Grant, 1927), lateral and oral views. Scale bars: A-L, N-P, 200 mm; M, 50 mm.