Wortheniopsis J. Böhm, 1895

Szabó, János, 2016, Gastropods of the Lower Jurassic Hierlatz Limestone Formation, part 2. Some new archaic type slit-bearing components from the fauna of the Hierlatz Alpe (Hallstatt, Austria) and the Bakony Mts (Hungary), Fragmenta Palaeontologica Hungarica 33, pp. 3-30 : 7-9

Genus Wortheniopsis J. Böhm, 1895

Type species – Pleurotomaria margarethae Kittl, 1894 , Marmolada Limestone, Ladinian (Middle Triassic)

Emended diagnosis – Moderately high turbiniform to subconoidal, thin walled shells of convex whorls. Earliest shell parts unknown. Suture variably impressed. Surface of early whorls evenly arched, later whorls having obscure spiral angulation adapically from midwhorl. Flat to concave ramp between upper suture and angulation. Flat or feebly concave selenizone between two spiral threads, abapical one just overlapping ridge of angulation. Feebly concave to feebly convex outer face, being wider than ramp. Transition from outer face to base widely and evenly arched. Base subglobose as whole with convex wall, anomphalous or narrowly phaneromphalous. Aperture rounded with angle at terminus of suture. Thin, smooth shell layer representing parietal lip; columellar/umbilical lip vertical, thin or weakly thickened. Ornament of spiral and collabral threads and granules on whorls, threadlike spiral ridges of asymmetric triangle cross-section on base and on outer face (quirinii type ridges). Growth lines feebly prosocline and fairly prosocyrt on both sides of selenizone, respectively, feebly opisthocline and opisthocyrt on base.

Remarks – All syntypes of Wortheniopsis margarethae are of very poor preservation, therefore the nature of the exhalant system, critical for classification, has remained debatable for the recently active researchers of the Triassic gastropods. The original descriptions and drawings do not provide satisfactory help to see doubtlessly if the type species has a slit and selenizone or only peristomal sinus and sinuszone on the whorls. Therefore a re-study of the specimens has become necessary for further discussion.

The restudy of the syntypes ( NHMV 1969 /1103) has confirmed, as their figures ( KITTL 1894, Pl. VI, Figs 1–3 ) also show, that even the best preserved syntype of the type species bears only very small pieces of badly worn shell fragments on inner mould and their outermost layer is lacking. Actually, the lines of the ornament are much more obscure than the drawings show them. A narrow, smooth and flattish ribbon between two eroded spiral threads represents the anal fasciole just adapically from an obscure angulation of the whorl surface, aligned to the abapical spiral thread. Some distinct lines of KITTL’s drawing (1894, Pl. VI, Fig. 2 ) show that the growth lines of the subsutural ramp and those of the outer face form a sharp angle at the ridge of the obscure angulation i.e. at the abapical spiral thread. Actually, those few lines that cross the belt between the two spiral threads are straight linear damages and are not aligned to the growth-lines. Waste majority of the collabral lines terminate at or before reaching the two spiral threads, limiting the smooth belt that must be therefore a selenizone. The selenizone is smooth like in the latest growth phases of the two new Jurassic species.

Similarly to Pleurotomaria margarethae , Turbo quirinii Stoppani, 1858 and Turbo funiculatus Stoppani, 1858 occurred in the same formation, the Marmolada Limestone (Ladinian, Middle Triassic). First MARIANI (1896) then KITTL (1899) regarded these species also as Wortheniopsis . The latter author has also unified the two latter species, however, as KITTL (1899, Pl. 14–15) figures show it, the interpretation of this species involves so significantly different morphologies that it might belong to two species.

According to unpublished data of S. Monari (Padua University), slitless, sinuszone bearing gastropod with morphology similar to the type species of Wortheniopsis occurs in the fauna of the Marmolada Limestone ( MONARI, pers. comm.).

The Late Triassic Wortheniopsis budensis Kutassy, 1927 , in lack of any traces of the exhalant system, is excluded from the comparisons. The name Wortheniopsis has also been applied to some Palaeozoic forms but their revision is out of the scope of this paper.

The emended diagnosis above is based on the study of the syntypes of the type species, Pleurotomaria margarethae Kittl, 1894 and monotypes of two new Jurassic species, Wortheniopsis rakusi n. sp. and Wortheniopsis bakonyensis n. sp. The morphology of these three species is similar to each other so they seem to be closely related.

The morphology of the growth lines in the new specimens permits to reconstruct elements of the outer lip that has not yet been found in preserved form. It is just very feebly prosocline, almost orthocline as a whole and composed of prosocyrt parts at both sides of the selenizone, respectively, and feebly opisthocyrt on the base. The growth lines meet the selenizone in 50–60° angles at its both sides. It probably means that the rim of the outer lip is angular at both sides of a peristomal fissure, like in Scissurellidae . This morphology is different in Pleurotomarioidea where a wide, strongly prosocline-prosocyrt growth line belt is characteristic adapically from the selenizone, prosocyrt and narrow belt between the base and the selenizone, and markedly parasigmoidal on the base. Furthermore, these growth lines asymptotically approach the selenizone, i.e. the rim of the peristome is widely arched at both sides of the slit. These differences support the non-pleurotomarioidean systematic position for Wortheniopsis . The sinus-bearing counterpart (“ Turbo ” quirinii Stoppani ) in the Middle Triassic seems to represent an earlier evolutionary stage, and suggests belonging to one of the archaic higher taxa. Although similar situation occurs also in some other family rank taxa, e.g. in Raphistomatidae , containing also genera of similar shell morphology, tentatively Pithodeidae is selected as family position for Wortheniopsis .

Distribution – Beside the Alpine Middle Triassic (Marmolada Limestone) here verified in the Lower Jurassic (Hierlatz Limestone).

Figures

Figs 1–3. The peculiar “quirinii type” ridges, occurring in Wortheniopsis Böhm, 1895, Foveolaria n. gen. and some probably related forms. – 1. Copy of KITTL’s (1899, p. 14, Fig. 2) sketch. – 2. The ridges on the outer face and on the base of Wortheniopsis rakusi n. sp. – 3. The ridges on the base of Foveolaria conoidea n. sp.