Abstract
Clypeina lagustensis n.sp. has been found in the Lower Tithonian deposits of the Lastovo Island (Dalmatia, Croatia). It is visually similar, obviously related and in some sections appearing almost identical, to Clypeina jurassica FAVRE, from which it differs by visible swellings and thinning of the central cavity, more pronounced distance between neighbouring whorls of fertile branches, and shape and structure of the interverticillate thallus parts, characterized by having well developed, hairy, sterile branches. These, after emerging from the exit pore, divide into several bundles which form a common turf with a calcareous envelope in the proximal part. Normal 0 21 false false false HR X-NONE X-NONE
Highlights
In the preparation for the new lithostratigaphic map of Croatia, the Croatian Geological Survey investigated several regions within the Dinarides, including the insular belt, in order to establish lithostratigraphic units suitable for correlation within the broader Dinaridic area
These included the morphology and structure of the thallus, as well as the values of some biometric parameters, which, in some earlier descriptions, seemed to be taken in variously oriented sections and, were ill-suited for comparisons. The reason for this seems to be the fact, that C. jurassica was both established (FAVRE & RICHARD, 1927) and subsequently determined by numerous authors, mostly involving transverse and oblique sections cutting one or at most a few (2-3) disks of fertile laterals, making it impossible to gain a complete insight into the thallus morphology and reliable values for most of the biometric parameters
This was previously noticed by REMANE (1969), who, in his detailed morphological and statistical analysis of some biometric parameters of C. jurassica, commented on the validity and usefulness of individual biometric parameters, which are mutually dependent on the type and the position of sectioning
Summary
In the preparation for the new lithostratigaphic map of Croatia, the Croatian Geological Survey investigated several regions within the Dinarides, including the insular belt, in order to establish lithostratigraphic units suitable for correlation within the broader Dinaridic area. According to the present state of availability of published material and presented opinions regarding the validity of C. inopinata, we agree with REMANE’S (1969) opinion, accepting comments and the opinions of SCHLAGINTWEIT, DIENI & RADOIČIĆ (2009) regarding the conservation of the already well-established species-specific name Clypeina jurassica FAVRE This short, partly reduced, review, of the earlier studies, opinions, supplements, and (taxonomically often confused) interpretations, including their deficiencies, was deemed necessary as a preliminary introduction to our further considerations, better understanding, and legitimacy for establishing an independent taxon for a new form, in spite of its visual similarity with C. jurassica, but displaying newly observed characteristics. We hesitated as to which taxonomic category this form should be assigned; should it be considered as a case of heteromorphism, variation, subspecies, or be separated as a new taxon? Taking all its specific features together, as a set of differences with regard to C. jurassica, and accepting the possibility that by gradual acquisition of new, more or less pronounced, features, species become the origin for another species, we decided to put this form in the species rank as Clypeina lagustensis n. sp
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