Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 26. 2008. (Budapest, 2008)
Diagnosis — Dextral species with biconcave shell; weak, not corrugated carinae on outer angulations of teleoconch; smooth shell with extremely fine growth lines. Material — A shelly specimen (holotype) and an internal mould with shell fragments (paratype, GBa 2008/69/34/2/2), found amongst Discohelix excavata specimens in the "background" material. Measurements H holotype *5 paratype 111 HPW D *16.8 *18 W *5 AS 210° AU *140 c *145 c Shape — Biconcave species with umbilicus slighdy deeper than spire. Protoconch somewhat elevated (its other characters uncertain because of strong re-cry T stallization). Number of whorls ~7. Spiral and umbilical side ot whorls flat, except last one where feebly concave; outer side moderately convex. Outer angulations of teleoconch rather sharp and bearing weak carinae, being not corrugated. Sculpture — Shell smooth with extremely fine growTh lines (visible only by strong magnification). Remarks — A similar species is the Aalenian to Early Bajocian Discohelix levis WENDT, 1968, having also no ornament and a comparable shape. However, the morphology and the measurements are clearly different. Adult D. levis specimens have strongly thickened outer lip, but the available Discohelix sima n. sp. specimens do not show any trace of this peristome modification. Discohelix sima n. sp. is comparable also to D. inornata SZABÓ, 1979 of similar stratigraphical occurrence that may have also no more ornament over growth-lines. However, in the latter species, the carinae of the outer angulations are lacking; the whorls are convex in all growth stages; the adult size is much bigger and the number of whorls in this stage is 9—10); the measurements are also significantly different An adult Discohelix inornata specimen has trumpet like peristome while the available Discohelix sima n. sp. specimens do not show any trace of an enlarged peristome/aperture. See distinction from Discohelix stolic^kai n. sp. below. Distribution — Hallstatt, Hierlatz Alpe, Upper Sinemurian (Oxynotum Zone). Figure 6 — Discohelix sima n. sp., holotype. — A: spire view; B: dorsal view; C: "aperture" view; D: umbilical view; A—D = xl; E: magnified (x3) view to show details of the shape and the ornament. Discohelix stoliczkai n. sp. (Figure 7) H o lotvpe- GBa 2008/69/34/3/1; paratype: NhM 2007/0101/0007. Type locality — Hallstatt, Flierlatz Alpe. Type strata — Sinemurian (Oxynotum Zone) Hierlatz Limestone. Name — Dedicated to Ferdinand STOLICZKA. Diagnosis — Biconcave, dextral species, consisting of narrow whorls with flat umbilical and spiral side; outer side strongly convex, angulations without carinae; last whorl expanding and its cross-section tends to change into circular; ornament consisting of very fine growth-lines only. Material — Four specimens, one (paratype) from the NhM, three ones from the "background" material in GBa, found in a Discohelix excavata box. M easurements holotype paratype H *5.5 *6 HI HPW *4.9 D *15.5 *16.8 W *3.5 *4.4 AS AU *227° 128° 127° Shape — Biconcave shells with somewhat uncertain dextral coiling direction; strongly re-crystallised and partly covered, badly visible protoconch in holotype seems feebly raised in (5°) deeper side of shell that may mean false sinistral (feebly ultra-dextral) coiling. Axial part of paratype (largest specimen) has poorly preserved central region, it seems wrongly cleaned from matrix, (therefore) showing "giant" nucleus of probably artificial origin (Figure 7: D, F). Whorls narrow, therefore rather numerous: 9 in holotype, being subadult specimen. Paratype has additional expanded half whorl with strongly convex outer side and strongly rounded outer angulations. Near (apparent?) peristome of paratype, last whorl section from suture to suture across outer side tending to change into circular outline. Earlier whorls have less, but clearly convex outer side. Outer angulations more distinct on spire whorls but no keels visible on most of them, except earliest juvenile teleoconch whorls. Suture does not coincide with top of angulations therefore feebly (asymmetrically) impressed. Spiral and umbilical sides of whorls flattened, sometimes feebly concave.
