Granulizona, Szabó, 2017

Szabó, János, 2017, Gastropods of the Lower Jurassic Hierlatz Limestone Formation, part 3. New pleurotomarioideans from the fauna of Hierlatz Alpe (Hallstatt, Austria), Fragmenta Palaeontologica Hungarica 34, pp. 9-48 : 43-44

Genus Granulizona n. gen.

Type species – Granulizona mandli n. sp.

Diagnosis – Trochiform shell with blunt apex and low, slightly convex whorls without spiral angulation on whorl surface; latest whorls more convex than early ones. Selenizone with median cord below midwhorl; base flattened subconoidal with slightly convex wall; rather broadly phaneromphalous. Last whorl turning into base through angular periphery. Early teleoconch bearing collabral riblets above selenizone and tubercles below. Cord of selenizone ornamented by granules. During growth, riblets and tubercles along sutures gradually vanishing but density of granules on selenizone increasing then fusing into smooth cord. Spiral threads of various thickness present on all whorls and on base.

Derivation of name – Referring to the granulate selenizone of the early teleoconch.

Description – See type species below.

Remarks – Since the earliest shell, the protoconch and one or two whorls, is insufficiently known, the family attribution is uncertain.

Some elements of the morphology and the ornament recall those of Pleurotomaria , Laevitomaria or Pyrgotrochus ; see details of the comparison in the “Remarks” of the type species below.

Species – Granulizona mandli n. sp.

Distribution – Within Sinemurian to lowermost Pliensbachian (Lower Jurassic) part of the Hierlatz Limestone Formation in Hierlatz Alpe, Hallstatt, Austria.