Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 26. 2008. (Budapest, 2008)
HL HP D W AA AL *4 *2.4 *4.3 *2.2 -170° 90° Measurements H lectotype *4.5 y a i Figure 71 — Guidonia rotula (STOLICZKA, 1861), lectotype (A-B) and paralectotype(C-D). — 7 a-c: copy of the original figures from STOLICZKA (1861) Tafel II; A-B: lectotype in apical view, A = xl, B = x8; C-D: paralectotype (GBa 2008/69/21/2) in apical view, C = xl,B = x8. Shape — Small, few (5) whorled shell of planispiral protoconch and gradate teleoconch. Protoconch consisting of two whorls; first half and initial chamber slightly impressed. First three whorls simply convex then angulation developes gradually below midwhorl, subdividing whorls into gently sloping, wide ramp and narrower outer face. Latter almost parallel to axis but abapicially feebly de\ r iates abaxially. Ramp becoming slighdy concave short after appearance, simultaneously with formation of keel on angulation; outer face does it also but in various growth stages in different specimens. Periphery angulate and carinate. Base convex and narrowly phanerompalous or ha\ r ing considerable false umbilicus. Peristome strongly prosocline, not in one plane and discontinuous, only thin inducture connect suture to columellar lip, being backward inclined. Sculpture — Protoconch seems to have no ornament. Spiral threads appear on third whorl first along suture then cover, on two specimens, complete whorl and also base. Third specimen has spiral threads only along suture and in outer, near periphery' belt of base. Collabrally, marked growth-lines cross the spiral ornamental elements on whole shell and low, periodically repeating ridges do it on the ramp. Ridges gently corrugating angulation at abaxial rim of ramp and subsutural swollen (cord-like) edge of whorls. Remarks — In the available small material two strongly different ornament appear but the shapes are similar. Two specimens hav^e the ornament, displayed in Figure 71: A-B (lectotype), this matches better to the original figuration. The other ornament type is much more delicate and lacks many elements of the previous sculpture; to find a possible taxonomical conclusion to these differences, further material is necessary. Guidonia rotula resembles to some Helicacanthus, and low spired Amphitrochus species; both genera are member of family Nododelphinulidae COX, 1960. COX accomodated this family in superfamily Amberleyoidea WENZ, 1938 (= Eucycloidea KOKEN, 1897). Guidonia resembles also Chartronella (Paramrbinidae, Palaeotrochoidea). This similarity also call the attention that a revision of Eucycloidea and Palaeotrochoidea is badly needed. Tentatively Nododelphinulidae regarded as independent family here but within Trochoidea. Distribution — Hallstatt, Hierlatz Alpe, Upper Sinemurian (Oxynotum Zone). Superfamily Eucycloidea KOKEN, 1897 Family Eucyclidae KOKEN, 1897 Subfamily Eucyclinae KOKEN, 1897 Genus Eucyclus}. A. EUDES-DESLONGCHAMPS, 1860 Subgenus Eucyclus]. A. EUDES-DESLONGCHAMPS, 1860 Type species: Eucyclus obeliscus). A. EUDES-DESLONGCHAMPS, 1860 Remarks — Beside the most common, low to high turbiniform species of the genus, moderately and strongly turriculate transformation of shells with Eucyclus morphology were also found in the Hierlatz Limestone material. Two of the three species, distinguishable amongst the "Chemnitina margaritacea STOLICZKA, 1861" syntypes, have rather slender shells of 18° and 25° coiling angle, respectively; [Eucyclus margaritaceus (STOL.) and Eucyclus sandrae n. sp.]. Their "cenogastropod-like" form caused some hesitation owing to their strongly fragmentary shells. However, their genus identification as Eucyclus was supported by the subturriculate form of the type species on one hand, and by the occurrence of a new species in the fauna with rather typical Eucyclus morpohology {Eucyclus mitterseensis n. sp.) that has rather high and acute shell of coeloconoidal outline with coiling angles, changing from —20° to 31°, on the other hand. GRÜNDEL (2007) also reported similar trouble in his paper, written about the Feuguerolles (Normandy, France) Pliensbachian gastropod fauna; he regarded the turriculate and cyrtoconoidal ProcerithiumQ) dimorphospira COSSMANN, 1913 as questionably belonging to Eucyclus.
