Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 16. 1993. (Budapest, 1993)

Apringia atla (Oppel, 1863) Capillirhynchia sp., aff. brentoniaca (Oppel, 1863) Nucleata tenuiplicata (Uhlig, 1881) Karadagithyris sp. Dorsoplicathyris ? sp. In addition to the hooked beak, the new rhynchonellid possesses a robust constitution and a giant size (at least a single, possibly gerontic specimen) and this recalls the similar relationships found at some other late Middle Jurassic rhynchonellids (e.g. Septirhynchia and "Rhynchonella" decorata). Apart from the strong morphological differences, they seem to be quite distant from paleobiogeographical and phylogenetical points of view as well. Nevertheless, the more or less synchronous appearance of these exaggerated forms points to an episode of "rhynchonellid gigantism" near the end of the Middle Jurassic. Therefore, in spite of the sparse material and the regrettable monotypy, it seems to be reasonable to erect a new genus on these unusual South Alpine forms. In this paper, the higher rank systematic categories developed by Ager et al. (1972) will be used. SYSTEMATIC DESCRIPTION Order RHYNCHONELLIDA Kuhn, 1949 Superümüy RHmCHONELLACEA Gray, 1848 Family Septirhynchiidae Muir-Wood & Cooper, 1951 The status of this family was endorsed in the "Treatise" (Ager 1965) and in Ager et al. (1972), later on, however, Mancenido & Walley (1979) lowered its rank to the subfamily level. The main reason for doing this was the monotypic character of the taxon. By the addition of Lessiniella, this reason vanishes and the status of the group can be restored with special reference to the strange, pentameroid shape of the taxa included. Genus Lessiniella gen. n. Derivatiö nominis: after the name of Lessini Mts. (Southern Alps, Italy). Type species: L. benettii sp. n. Diagnosis: Large sized rhynchonellids, valves strongly convex, gibbose, urnbones massive, beaks strongly incurved. Dorsal fold and ventral sulcus weak, anterior commissure uniplicate to parasulcate. Planareas well-developed. Dental plates and pedicle collar are present. Cardinal process is formed by a blade-like extension of the dorsal umbo. Septalium slightly overturned. Dorsal median septum well-developed, long. Crural bases emerge dorsally, crura radulifer. Discussion: Lessiniella was included in the family Septirhynchiidae after some hesitation. At first sight it seems to be very different from Septirhynchia because of the lack of ribbing. However the giant size and the gibbose, pentameroid appearance are more important common external features. The internal morphology of the two genera matches rather well; difference is only in the ventral umbo, namely the absence of median septum in Lessiniella. The genus Heteromychus Cooper (Cooper 1989, p. 41) seems to be transitional from this point of view. It is