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Paolo Stara

  • Biodiversity Journal, 8 (2): 315-389 - MONOGRAPH

    Paolo Stara & Enrico Borghi
    Revision of the genus Amphiope L. Agassiz, 1840 (Echinoidea Astriclypeidae) with the description of a new species from the Miocene of France

    ABSTRACT
    The taxonomy of Amphiope L. Agassiz, 1840 (Echinoidea, Astriclypeidae), an echinoid distributed in the Oligo-Miocene of Central and Southern Europe, is largely unresolved since the description of most species attributed to this genus was based only on the external morphological features, while important characters, such as the oral plating and the internal support system, were poorly illustrated or completely omitted. Additionally, the type material of some species was missing or badly preserved and geographical/stratigraphical information about the type-locality was unclear. This was the case also for Amphiope bioculata (Des Moulins, 1837), the type species of the genus. The poor definition of the earlier described species of Amphiope prevented comparison with fossils from other localities and ages, subsequently attributed to this genus. A large part of the earlier species of Amphiope, key-taxa for the resolution of the complex taxonomy of this genus, are herein revised by modern methods. For this purpose, the type material available in public institutions has been re-examined and, when possible, new topo-typic material has been collected. As a result, the morphological description of A. bioculata has been completed based on fossils from the Middle Miocene of Hérault (France), which is here considered as the type area. The redefinition of the type species allowed to extend comparison and taxonomic discussion to other species earlier attributed to Amphiope. Seventeen species are herein confirmed as valid and maintained in the genus Amphiope. Three additional species so far attributed to Amphiope have been transferred to the genus Paraamphiope Stara et Sanciu, 2014: P. agassizi (Des Moulins in Cotteau, 1865), P. cherichirensis (Thomas et Gauthier, 1889) and P. baquiei (Lambert, 1907). Amphiope boulei Cottreau, 1914, has been assigned to the genus Sculpsitechinus Stara et Sanciu, 2014. Amphiope romani n. sp. is described on the basis of a sample from the Serravallian-Tortonian of Touraine (France); it is distinguished mainly by the periproct very close to the posterior margin and the lack of sinus in correspondence of the frontal ambulacra.

  • Biodiversity Journal, 7 (4): 935-944 - MONOGRAPH

    Yaser Fatemi, Gilan Attaran-Fariman & Paolo Stara
    Sculpsitechinus iraniensis n. sp. (Clypeasteroida Astriclypeidae), from Chabahar Bay, southeast coast of Iran

    ABSTRACT
    In the past, the practice of giving more weight to the outer shape of echinoderms than the structural characters, has led to misinterpretations in the systematics within the family Astriclypeidae Stefanini, 1912 (Clypeasteroida). We do not know, often, what the previous researchers were referring to when they refer to Echinodiscus, since many of these, in fact, belong to the genus Sculpsitechinus (at present including two species: S. auritus and S. tenuissimus). Every sand dollar that had two posterior ambulacral slots opens on the rear edge, was always classified as “E. auritus” now accepted as S. auritus. In fact, this general form, common across the Indian Ocean and spread to Indonesian Archipelago, until the Western Pacific, shows, locally, strong differences that justify a change in the specific allocation. A new form of living Sculpsitechinus was found from the sediments at low tide of Chabahar Bay, located along the Iranian coast of the Gulf of Oman. The analysis of morphometric and structural data, allowed us to establish this form as a new species: S. iraniensis n. sp. This new species differs from the type species of S. auritus mainly by the considerable size of the petalodium, that reaches the mean of 55% of test length, in comparison to the mean of 40% of the type test length. Moreover, the studied population shows considerable variability in the plating scheme of the adoral face, which will give rise to future insights.

  • Biodiversity Journal, 7 (4): 387-388
    Paolo Stara
    Echinoids and paleo-geographic reconstructions
  • Biodiversity Journal, 6 (1): 393-400 - MONOGRAPH

    Paolo Stara, Federico Marini, Giuseppe Carone & Enrico Borghi
    Distribution of two Amphiope L. Agassiz, 1840 (Echinoidea Clypeasteroida) morphotypes in the Western-Proto-Mediterranean Sea
    Proceedings of the 2nd International Congress “Speciation and Taxonomy”, May 16th-18th 2014, Cefalù-Castelbuono (Italy)

    ABSTRACT
    Several species belonging to the genus Amphiope L. Agassiz, 1840 (Echinoidea Astriclypeidae) from the Mediterranean Oligo-Miocene have been synonymised with A. bioculata (Des Moulins, 1835), the type-species of the genus, based on the interpretation given by Philippe (1998) as a taxon characterized by a large amount of morphological variability. A recent study introduced the characters of the internal test structure and the plating patterns as taxonomic tools in this genus. That paper indicated the occurrence of at least five different species in the examined sample from the Oligo-Miocene of Sardinia, thus pointing to a previous overestimation of the variability-range of the type-species and to the need of a review of the largely unresolved taxonomy of Amphiope. According to a recent study, Amphiope is considered as a shallow-water echinoid, inhabiting sandy bottoms with high hydrodynamic energy; so it represents a coastline marker, useful for the study of the paleo-geographic changes occurred in the Proto-Western-Mediterranean during the Miocene. The diffusion and speciation of Amphiope were highly influenced by those changes. In particular, the speciation rate of this genus was likely favored by the occurrence of isolated populations created when islands (e.g.: Baleares, Calabria, Corse, Kabylies, Sardinia) separate from the mainland, above all in the western part of that Basin, because of the opening of the Balearic Basin during the Late Oligocene-Early Miocene and of the Tyrrhenian Sea during the Burdigalian-Tortonian (references in this work). Two main morphotypes of Amphiope sensu Stara & Sanciu (2014), developed in the Western Mediterranean from the late Oligocene to the late Miocene. They are herein called the “bioculata” group, characterized by roundish to broad elliptical lunules with major diameter/minor diameter ratio (SI) < 1.59, and the "nuragica" group, with more or less narrow lunules and SI > 1.6. According to this authors, most Miocene forms with narrow elliptical lunules would derive from A. nuragica (Comaschi Caria, 1955), late Oligocene-early Miocene of Sardinia, the most archaic form so far known of this genus. The forms belonging to the “bioculata” group likely derived from a different common ancestor bearing round to broad ovoidal lunules. “A. bioculata” described by Cottreau (1914), from the Burdigalian (Philippe, 1998) of Saint Cristol (Nissan, Herault, France), is so far the most ancient known form belonging to this group. This work proposes a possible speciation sequence of the “nuragica” group.

  • Biodiversity Journal, 5 (2): 291-358 - MONOGRAPH

    Paolo Stara & Luigi Sanciu
    Analysis of some astriclypeids echinoids (Echinoidea Clypeasteroidea)

    ABSTRACT
    The systematic position of some astriclypeid species assigned through times to the genera Amphiope L. Agassiz, 1840 and Echinodiscus Leske, 1778 is reviewed based on the plating pattern characteristics of these two genera universally accepted, and on the results of new studies. A partial re-arrangement of the family Astriclypeidae Stefanini, 1912 is herein proposed, with the institution of Sculpsitechinus n. g. and Paraamphiope n. g., both of them characterized by a peculiar plating-structure of the interambulacrum 5 and of the ambulacra I and V. Some species previously attributed to Amphiope and Echinodiscus are transferred into these two new genera. Two new species of Astriclypeidae are established: Echinodiscus andamanensis n. sp. and Paraamphiope raimondii n. sp. Neotypes are proposed for Echinodiscus tenuissimus L. Agassiz, 1840 and E. auritus Leske, 1778, since these species were still poorly defined, due to the loss of the holotypes and, for E. auritus, also to the unclear geographical/stratigraphical information about the type-locality. A number of additional nominal fossil and extant species of "Echinodiscus" needs revision based on the same method.

  • Biodiversity Journal, 5 (2): 269-290 - MONOGRAPH

    Paolo Stara & Maurizio Fois
    Analysis on a sample of Echinodiscus cf. auritus Leske, 1778 (Echinoidea Clypeasteroida)

    ABSTRACT
    In order to ascertain the extent of the natural intraspecific variability of living and fossil echinoids belonging to the family Astriclypeidae Stefanini, 1912, morphometric and structural aspects were examined in a number of specimens of extant Echinodiscus cf. auritus Leske, 1778, from Madagascar and Philippines. The data obtained will be compared, in a following work, with those of other echinoids belonging to the same family. The analysis of the results indicates, for the sample studied, a great variability in the length of the posterior ambulacral notches, in the petaloid length and in the position of the periproct respect to the posterior margin, while the study of the complete scheme of the plates has clarified the sta- bility and constancy of some parts of this scheme and the variability of other. On the basis of these observations, it has been claimed that the variability of these measures is not so extensive as to affect or determine specific distinctions, if used without careful analysis of the plating pattern in particular in the interambulacrum 5 and in the ambulacra I and II. The results of these analyses, finally, suggests that these echinoids belong to a different genus, than Echinodiscus Leske, 1778.

  • Biodiversity Journal, 5 (2): 245-268 - MONOGRAPH

    Paolo Stara & Enrico Borghi
    The echinoid genus Amphiope L. Agassiz, 1840 (Echinoidea Astriclypeidae) in the Oligo-Miocene of Sardinia (Italy)

    ABSTRACT
    The records of the genus Amphiope Agassiz, 1840 (Astriclypeidae) from Sardinia are revised on the basis of 110 specimens, collected from 15 localities of Oligo-Miocene age. Since the morphological characters stated in the literature to distinguish the species of Amphiope described in this region cannot provide a clear separation between them, analyses of the plate patterns and of the internal test structure are introduced as taxonomic tools useful for species-level taxonomy in this genus. Five different species of Amphiope are identified. Three of the six species erected on the basis of fossil material from Sardinia are confirmed as valid: Amphiope lovisatoi Cotteau, 1895, A. montezemoloi Lovisato, 1911 and A. nuragica (Comaschi Caria, 1955). Two additional species are left in open nomenclature. The morphological descriptions and the stratigraphical distributions are updated and improved.

  • Biodiversity Journal, 5 (2): 233-244 - MONOGRAPH

    Paolo Stara & Roberto Rizzo
    Paleogeography and diffusion of astriclypeids (Echinoidea Clypeasteroida) from Proto-Mediterranean basins

    ABSTRACT
    In this paper, the authors retrace the geological changes that during the Neogene have modified the paleogeography of the Western Mediterranean up to its current set-up. It is assumed that migration and probably also speciation of the involved astriclypeids (particularly Amphiope L. Agassiz, 1840 and Echinodiscus Leske, 1778) are closely related to those changes.

  • Biodiversity Journal, 5 (2): 229-232 - MONOGRAPH

    Paolo Stara & Daniele Fois
    Dispute about Echinodiscus Leske, 1778 and Amphiope L. Agassiz, 1840 (Echinoidea Astriclypeidae)

    ABSTRACT
    Between the late 1800s and early 1900s, some European echinologists gave rise to a dispute over belonging to the genus Amphiope Agassiz, 1840, rather than Echinodiscus Leske 1778, of some lunulate scutelliforms present in the Oligocene-Miocene deposits of France and Italy. The problem has never been resolved, due to the fact that these echinologists considered the similarities or differences in shape, rather than structural ones. One of the nodes of the dispute was the variability in shape and size of the lunules in Amphiope. Because of all these problems, and also because of the impossibility to obtain and examine the structures of some type specimens of several species established in the past, the recognition of new species is very complicated and research carried out so far, in many cases is doubtful or controversial.

  • Biodiversity Journal, 5 (2): 225-228 - MONOGRAPH
    Paolo Stara
    Preface. Studies on extant and fossils astriclypeids (Echinoidea Clypeasteroida)