Jurilda elongata ( Leonardi and Fiscon, 1959 ) Hausmann & Nützel & Roden & Reich, 2021

Hausmann, Imelda M., Nützel, Alexander, Roden, Vanessa Julie & Reich, Mike, 2021, Palaeoecology of tropical marine invertebrate assemblages from the Late Triassic of Misurina, Dolomites, Italy, Acta Palaeontologica Polonica 66 (1), pp. 143-192 : 164-165

Jurilda elongata ( Leonardi and Fiscon, 1959) comb. nov.

Fig. 20 .

1959 Promathildia (?) peracuta n. var. elongata; Leonardi and Fiscon 1959: pl. 9: 14, 15, 20.

1978 Promathildia peracuta f. elongata (Leonardi-Fiscon) ; Zardini 1978: pl. 35: 24, 25, non 23.

1995 Tirolthilda seelandica n. sp.; Bandel 1995: 13, pl. 5: 6, 8–10.

Material.— One hundred and seventy specimens, 171 from bulk samples, 1 from surface samples; 5 from Lago Antorno ( PZO 12838 , 5 specimens); 167 from Misurina Landslide ( PZO 12716–12720 , 5 figured specimens; PZO 12635 , 162 specimens; Italy, Carnian , Triassic.

Description.—Shell high-spired, slender, largest illustrated specimen 3.7 mm high, 1.4 mm wide (apex broken off); two prominent spiral cords present immediately after protoconch; spiral cords relatively close to each other on early whorls and widely separated on later whorl; whorl angulated at spiral cord so that whorl face is bevelled towards sutures; whorl straight to slightly concave between spiral cords; whorl angulated with fine axial threads which are much weaker than spiral cords; axial threads straight between spiral cords, prosocline above adapical spiral cord and opisthocline below abapical spiral cord; number of axial threads increases to up to more than 30 per mature teleoconch whorls; bordering spiral cord emerges at suture and is fully exposed on base.

Remarks.— Leonardi and Fiscon (1959) described this species from Costalaresc as variety of Flemingia bicarinata Kittl, 1891 (placed tentatively in Promathildia by them), a species from the Middle Triassic Esino Limestone. Since this variety was published before 1961 it has subspecific rank ( ICZN Article 45.6.4.). Leonardi and Fiscon (1959) discussed several characters separating Flemingia bicarinata from their new variety. Therefore, they clearly had the intention to describe a new taxon and not an infrasubspecific name as becomes obvious from the synonymy list provided by them. Bandel (1995) was aware that his material is conspecific with the variety described by Leonardi and Fiscon (1959) but nevertheless described the species as new ( Tirolthilda seelandica ). We raise Promathildia (?) peracuta n. var. elongata to species rank, there is no doubt that the morphological differences mentioned by Leonardi and Fiscon (1959) (ribbing, shape) are sufficient to raise it from subspecies rank. Tirolthilda seelandica Bandel, 1995 , falls in synonymy of Jurilda elongata .

The Middle Jurassic type species of Jurilda as reported by Walther (1951), Gründel (1973, 1997a) and Kaim (2004) closely resembles Jurilda elongata from the Cassian Formation. The only major difference is that the apical carination is stronger and thus the whorl face above it is oblique instead of parallel to the shell axis. Gründel and Nützel (2013) gave an emendated diagnosis of Jurilda which fits the present material well. Especially the ornament with two primary spiral cords close to the sutures which are crossed by fine axial threads is similar. Thus placement of Jurilda seelandica in Jurilda and the synonymisation of Jurilda and Tirolthilda are justified. It is the first report of this genus from the Triassic.

Bandel (1995) reported about 40 specimens from the type locality Alpe di Specie (Seelandalpe) and three specimens from Misurina. Zardini (1978) reported that it is very abundant at Misurina, abundant at Alpe di Species and rare at Costalaresc and Campo. Here it is one of the most abundant species at Misurina Landslide but very rare at Lago Antorno.

Stratigraphic and geographic range.—Only known from the Carnian, Upper Triassic; northern Italy (Cassian Formation).

Figures

Fig. 20. Mathildid gastropod Jurilda elongata (Leonardi and Fiscon, 1959) from Misurina Landslide, northern Italy, Cassian Formation, Carnian, Upper Triassic.A. PZO 12716, in lateral view (A1),A2, early whorls including heterostrophic protoconch, in lateral view.B. PZO 12717, in apical (B1) and lateral (B2) views; B3, early whorls including heterostrophic protoconch, in lateral view. C. PZO 12718, in apertural (C1) and oblique basal (C2) views. D. PZO 12719, in lateral (D1) and oblique basal (D2) views. E. PZO 12720, detail teleoconch whorl, in lateral view.