Metaxia sp., Monterosato, 1884

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 : 337

Metaxia sp.

(Fig. 5C1-C4)

MATERIAL EXAMINED. — Sample F11: AMPG ( IV) 2443, 2444 (two specimens).

DIMENSIONS. — Maximum height: 1.55 mm (incomplete).

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

DESCRIPTION

Dextrally coiled species of elongate, turriculate shape. High, multispiral protoconch with 4.5 whorls; protoconch I convex with delicate sculpture of zigzag spiral threads; protoconch II with narrow axial riblets; keel slightly below midwhorl increasing in strength towards teleoconch. Teleoconch incomplete, consisting of four convex whorls; apical angle of teleoconch 21°. Sculpture comprising 5 spiral cords: two weak cords in adapical part of whorl, two more prominent median ones of which upper one coincides with periphery; one weak spiral cord at abapical suture.

Spiral cords cover broad axial ribs, forming weak nodular intersections on median spiral cords. Aperture missing.

REMARKS

The present species has a similar morphology to the type species of the genus, Metaxia metaxa (Delle Chiaje, 1828) , has a protoconch of 3.5 whorls and flatter teleoconch whorls. Athother similar species is Metaxia carinapex van der Linden, 1998 from the eastern Atlantic which has a lecithotrophic protoconch of 2.5 whorls and a teleoconch sculpture is less prominent with less broad axial ribs.

Regarding fossil species, sculpture and morphology are reminiscent of Metaxia permacra Lozouet, 1999 from the Late Oligocene of the Aquitaine Basin ( France) ( Lozouet 1999), which differs mainly in its more slender outline, strongly incised suture and the protoconch, which comprises only 3.5 whorls. Metaxia merignacensis ( Cossmann & Peyrot 1922) from the Early Miocene of the Aquitaine Basin differs in its extremely elongate shell, prominent spiral cords and shorter protoconch of 3.5 whorls. Although Metaxia degrangei sensu Marquet (1996) , from the early Miocene of the North Sea Basin is considered a synonym of M. merignacensis by Lozouet et al. (2001), it is morphologically distinct. The common features with the Greek species include a similar teleoconch sculpture and shell shape, but differences in the protoconch with 5.5 whorls with two spiral keels ( Marquet 1996) set it as a separate species.