Coelochrysalis Kittl, 1894

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 : 156-158

Genus Coelochrysalis Kittl, 1894

Type species: Melania pupaeformis Münster, 1841 ; Italy, Late Triassic.

Coelochrysalis pupaeformis ( Münster, 1841)

Fig. 12E, F .

1894 Euchrysalis (Coelochrysalis) pupaeformis ; Kittl 1894: 225, pl. 6: 15–20.

Material.— Two specimens ( PZO 12714 , 12715 ) from the Misurina Landslide surface samples, Italy, Carnian, Triassic .

Description.— Two specimens show the characteristic pupoid shape of this species that is produced by the constriction of the body whorl. The whorls are low; the larger specimen is 18 mm high. Both specimens lack the early whorls and are compressed.

Remarks.— Fürsich and Wendt (1977) reported a single specimen from their Ampullina association.

Unidentified caenogastropod

Fig. 12A .

Material.— Two specimens ( PZO 12829 , 12828 ) from Lago Antorno surface samples, Italy, Carnian, Triassic .

Description.—Two small fragments of a smooth shelled high-spired gastropod species that may represent Caenogastropoda.

Genus Helenostylina Kaim, Jurkovšek ,

and Kolar-Jurkovšek, 2006

Type species: Helenostylina mezicaensis Kaim, Jurkovšek, and Kolar-Jurkovšek, 2006 ; Slovenia, Late Triassic.

Helenostylina convexa Nützel and Kaim, 2014 Fig. 13 .

1992 Ptychostoma sanctaecrucis ( Laube, 1868) ; Bandel 1992: 52, pl. 6: 4, 5.

1994 Ptychostoma sanctaecrucis ( Laube, 1868) ; Bandel 1994: pl. 4: 8.

2014 Helenostylina convexa n. sp.; Nützel and Kaim 2014: 418, fig. 7e–h.

Material.— Thirteen specimens, 7 from bulk samples, 6 from surface samples; 10 from Lago Antorno ( PZO 12812–12814 , 3 figured specimens; PZO 12811 , 7 specimens); 3 from Misurina Landslide and Misurina Skilift ( PZO 12694 , 12695 , 2 figured specimens; PZO 12693 , 1 specimen); Italy, Carnian , Triassic .

Description.—Shell turbiniform, conical; apical angle about 70°; illustrated specimen from Misurina Landslide ( Fig. 13E ) with about seven whorls, 4 mm high, 2.8 mm wide; last whorl higher than spire; teleoconch whorls smooth, convex, without shoulder; base flatly convex with two spiral ribs and furrows surmounting the centre of the base; aperture as high as wide; protoconch comprising about 3.5–4 whorls, 0.4–0.5 mm high and wide, with about same apical angle as teleoconch (70–80°); initial whorl smooth with a diameter of about 0.14 mm; larval whorls convex, somewhat angulated at lower third; larval whorls with subsutural row of tubercles, followed by a smooth zone below extending to the whorl angulation; lower zone between angulation and abapical suture ornamented with 5–6 rows of fine tubercles; larval shell ends abruptly.

Remarks.—This species has a very characteristic larval shell of rows of small tubercles below the suture and on the lower third of the larval whorls separated by a wide smooth zone. Our material resembles the more juvenile type specimens as reported by Nützel and Kaim from the Settsass Scharte—one of their figured specimens ( Nützel and Kaim 2014: fig. 7e) shows the tubercular ornament on the larval shell although it was not mentioned in the description. The same species and larval shell was reported by Bandel 1992, 1994) who assigned it to Ptychostoma sanctaecrucis ( Wissmann, 1841) [erroneously cited as Ptychostoma sanctaecrucis ( Laube, 1868) by Bandel (1992, 1994)]. However, Bandel’s (1992, 1994) illustrated specimen from the locality Campo near Cortina d’Ampezzo does not represent P. sanctaecrucis . Ptychostoma sanctaecrucis was first described from the type location of the Heiligkreuz Formation which overlies the Cassian Formation. This species lacks the spiral ornament on the base and is larger. Moreover, Ptychostoma sanctaecrucis has a smaller larval shell which is ornamented by spiral crests, the same type that is present in Prostylifer (own observation on material from the type locality).

Helenostylina mezicaensis Kaim, Jurkovšek, and Kolar-Jurkovšek, 2006 , the type species of Helenostylina resembles H. convexa in shape and in having a spiral ornament around the umbilicus. However, this species has a subsutural ramp and the protoconch is seemingly smooth.

Omphaloptycha muensteri ( Wissmann, 1841) is similar. However the type specimen (SNSB-BSPG AS VII 1676) lacks circumumbilical spiral ribs and furrows and its whorls are higher. The type is larger (height 7 mm) than the specimens assigned to Helenostylina convexa by Nützel and Kaim (2014) and herein. The possibility that Omphaloptycha muensteri has basal spiral ribs and furrows only in the middle whorls but not on a more mature growth stage as present in the type specimen cannot be ruled out. If this is the case, Helenostylina convexa could represent a synonym of Omphaloptycha muensteri but this is seen as unlikely.

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

Family Prostyliferidae Bandel, 1992

Genus Prostylifer Koken, 1889

Type species: Melania paludinaris Münster, 1841 ; Late Triassic , Italy .

Prostylifer paludinaris ( Münster, 1841)

Fig. 14 .

1841 Melania paludinaris n. sp.; Münster 1841: 97, pl. 9: 50.

1992 Prostylifer paludinaris ( Münster, 1841) ; Bandel 1992: 50, pl. 5: 3–6.

1993 Prostylifer paludinaris (von Münster, 1841) ; Bandel 1993: 49, pl. 6: 1.

1994 Prostylifer paludinaris ( Münster, 1841) ; Bandel 1994: 143, pl. 4: 10.

Material.— Two hundred eighty three specimens, 152 from bulk samples, 131 from surface samples; 105 from Lago Antorno ( PZO 12823 , 12824 , 13680 , 3 figured specimens; PZO 12821 , 102 specimens); 178 from Misurina Landslide ( PZO 12699 , figured specimen; PZO 12698 , 177 specimens); Italy, Carnian , Triassic .

Description.—Shell littoriniform to turbiniform, bulbous; spire conical, acute; shell with 8 whorls (including protoconch), 5.0 mm high, 3.8 mm wide ( Fig. 14A ); last whorl much higher than spire; whorls strongly convex; sutures distinct; teleoconch whorls smooth; base rounded, evenly convex, not demarcated from whorl face, cryptomphalous; aperture oblique teardrop-shaped; inner lip oblique, evenly arched; columellar lip strengthened, somewhat reflexed; protoconch orthostrophic, mammilate, in general more slen- der than teleoconch; protoconch consisting of about 3.1–3.2 whorls, 0.33–0.40 mm high, 0.42–0.45 mm wide; initial whorl smooth, with diameter of 0.14–0.15 mm; protoconch whorls convex, ornamented with up to six sharp, narrow spiral crests; spiral crests evenly spaced, separated by wide concave interspaces; spiral crests crenulated with fine tubercles; abapical crest emerges at lower suture; additional crests present on convex base of the larval whorls; larval shell terminates abruptly with a distinct sinusigera; larval projection largely covered by succeeding teleoconch whorls; illustrated specimen from Misurina Landslide ( Fig. 14D ) comprising about seven whorls; last whorl broken; shell 2.1 mm high, 1.7 mm wide; protoconch 0.43 mm high and 0.4 mm wide.

Remarks.—This material from Lago Antorno and Misurina Landslide agrees well with the specimens illustrated by Bandel (1992: pl. 5: 3–6) which were reported from the localities Misurina, Alpe di Specie, and Costalaresc by this author. It also agrees with Münster’s (1841) type specimens at the Bavarian State Collection. One of the specimens illustrated by Bandel (1992: pl. 5: 5) has shouldered teleoconch whorls; Bandel (1992) also mentioned a great variation in the course of the growth line from slightly opisthocyrt to specimens which have an apertural sinus in the upper part of the whorls. Moreover, he mentioned the presence of a fine spiral striation on some specimens. This character was not observed in the present material. The larval shells documented by Bandel (1992) agree well with those in the present material.

Stratigraphic and geographic range.—Carnian, Triassic; northern Italy (Cassian Formation); Germany (eastern Alps, Raibler Schichten; northern Alps, Cardita Schichten ); China, Yunnan; Timor; Bulgaria ( Diener 1926; Kutassy 1940; Sachariewa-Kowatschewa 1962).

Figures

Fig. 12. Caenogastropods from Lago Antorno (A) and Misurina Landslide (B–F), northern Italy, Cassian Formation, Carnian, Upper Triassic. A. Unidentified caenogastropod, PZO 12829, in lateral view.B. Coelostylina sp.1, PZO 12691, in apertural view. C. Coelostylina sp. 2, PZO 12692, in lateral view. D. Flemingella bistriata (Münster, 1841), PZO 12713, in apertural view. E. Coelochrysalis pupaeformis (Münster, 1841), PZO 12714, in lateral view, with constriction of last whorl. F. Coelochrysalis pupaeformis (Münster, 1841), PZO 12715, deformed specimen in lateral view, showing constriction of last whorl.

Fig. 13. Coelostylinid gastropods Helenostylina convexa (Nützel and Kaim, 2014) from Lago Antorno (A, B, C), Misurina Skilift (D), and Misurina Landslide (E), northern Italy, Cassian Formation, Carnian, Upper Triassic. A. PZO 12812, relatively large specimen with well-preserved base with spiral ribs, in apertural view (A1); A2, early whorls in lateral view; A3, basal view showing spiral ribs; A4, oblique basal view showing spiral ribs on base. B. PZO 12813, relatively large specimen with spiral ribs on base and protoconch with tubercles, in apertural view (B1); B2, close up of base showing spiral ribs on base; B3, early whorls with tubercles on larval shell, in lateral view. C. PZO 12814, juvenile shell with tubercles on larval shell, in lateral view. D. PZO 12694, juvenile shell with tubercles on larval shell and healed shell fracture, in apertural (D1) and lateral (D2, D4) views; details showing end of larval shell (arrows), in lateral (D3) and apical (D5) views. E. PZO 12695, relatively large specimen with well-preserved base with spiral ribs and protoconch with tubercles, in apertural view (E1); E2, oblique apertural view to show base with spiral ribs; E3, protoconch in lateral view.

Fig. 14. Prostyliferid gastropods Prostylifer paludinaris (Münster, 1841) from Lago Antorno (A–C) and Misurina Landslide (D), northern Italy, Cassian Formation, Carnian, Upper Triassic. A. PZO 13680, relatively large specimen with preserved protoconch and inner lip, in apertural view (A1); A2, close up showing umbilical chink and arched inner lip; A3, apex with mammilated protoconch having spiral crests, in lateral view. B. PZO 12823, juvenile specimen with protoconch having spiral crests, in apertural view. C. PZO 12824, juvenile specimen with protoconch having spiral crests; C1, larval shell ending at sinusigera, in apertural view; C2, close up of whorl of larval shell. D. PZO 12699, juvenile specimen with mammilated protoconch having spiral crests, in lateral view (D1); D2, early whorls, larval shell ending at sinusigera, in lateral view.