Xenophora, Fischer von Waldheim, 1807

Thivaiou, Danae, Harzhauser, Mathias & Koskeridou, Efterpi, 2019, Early Miocene Gastropods from the Felli Section (Proto-Mediterranean Sea NW Greece), Geodiversitas 41 (8), pp. 323-366 : 341-342

Xenophora sp.

( Fig. 5 I1-I4)

MATERIAL EXAMINED. — Sample F10: AMPG ( IV) 2461 (one specimen).

DIMENSIONS. — Mean diameter: 5.10 mm (incomplete).

DISTRIBUTION. — Early Miocene. Proto-Mediterranean Sea: Greece (this paper).

DESCRIPTION

A fragment comprising 5 flat, teleoconch whorls shouldered on the abapical suture; apical angle 80°. Suture regular, deeply incised; small circular grains are attached along the suture. Base and aperture of the shell missing.

REMARKS

Due to the fragmentary preservation a clear identification is difficult. The apical angle is similar to X. deshayesi (Michelotti, 1847) and X. italica ( Grateloup, 1845); the apex and first teleoconch whorls of the specimen from Felli are most similar to X. italica mainly because of the flattened whorls and the linear suture that is visible when not obstructed by the agglutinated elements as it is observed for this species in Landau et al. (2013).

According to Ponder (1983), important characters for the separation of species of Xenophoridae are missing from the specimen of Felli, such as the sculpture and shape of the base, the width of the peripheral flange, the umbilical characters and the shape of the basal lip. The characters used here are the spire angle, the shape of the whorls and the mode of attachment of particles. Like the specimen from Felli, X. italica is reported to agglutinate smaller-sized objects such as sand grains and small shell fragments ( Landau et al. 2013). Nevertheless, it is doubtful that the specimen from Felli is conspecific with X. italica, as this species is known so far exclusively from middle Miocene localities ( Landau et al. 2013).

Xenophora cumulans (Brongnart, 1823) sensu Harzhauser (2004) from the Oligocene of the Mesohellenic Basin is distinctly different, mainly by having an apical angle that varies between 90 and 100°.

Xenophorids are known to be deposit feeders living on mobile bottoms ( Ponder 1983).

Figures

FIG. 5. — A1, A2, Nodiscala cf. rugatina de Boury in Cossmann, 1912: A1, A2, AMPG(IV) 2335; B1, B2, Triphora (s.l.) sp.: B1, AMPG(IV) 2439 (SEM image); B2, AMPG(IV) 2439, protoconch (SEM image); C1-C4, Metaxia sp.: C1, AMPG(IV) 2443, protoconch (SEM image); C2, AMPG(IV) 2443 (SEM image); C3, C4, AMPG(IV) 2443; D1-D3, Dizoniopsis sp.: D1, D2, AMPG(IV) 2445; D3, AMPG(IV) 2446 (SEM image); E1, E2, Rissoina subconoidea (Grateloup, 1847); E1, E2, AMPG(IV) 2448; F1, F2, Zebinella sp., AMPG(IV) 2451; G1-G4, Alvania amphitrite n. sp.: G1, G2, holotype, AMPG(IV) 1503; G3, paratype 2, AMPG(IV) 1505 (SEM image); G4, paratype 2, AMPG(IV) 1505, protoconch (SEM image); H1-H4, Alvania transiens (Sacco, 1895): H1, H2, AMPG(IV) 2455; H3, AMPG(IV) 2456 (SEM image); H4, AMPG(IV) 2456, protoconch (SEM image); I1, I2, Xenophora sp., AMPG(IV) 2461. Scale bars: A,D1-D3, F1, F2, G1, G2, H1-H3, 1 mm; B1, C2-C4,E1, E2, G3,500 µm; B2, H4, 400 µm; C1, G4, 200 µm; I1, I2, 2 mm.