Genero berria, Stegasteridae (Echinoidea) Coniaciarreko Euskokantauriar arroko sakoneko faziesekoa

• Autores: Enric Forner i Valls, José Kruz Arbilla Karasatorre, Txema Moreno
• Localización: Nemus: revista de l'Ateneu de Natura, ISSN 1697-2694, Nº. 11, 2021, págs. 187-204
• Idioma: euskera
• Títulos paralelos:
  • New genus of Stegasteridae (Echinoidea) from the Coniacian deep facies of the Basque-Cantabrian basin
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• Resumen
  • euskara

    Gaur egungo Holasteroida Durham & Melville, 1957, ordenako ekinidoak itsaso sakonean soilik bizi dira. Ekinido guztien artean batimetria handiagoko eremuetan bizi direnak ditugu (Smith & Kroh, 2020), nahiz eta Kretazeoan holasteroideo batzuk sakonera gutxiko uretan egon bazeuden. Haien arteko erlaziorik gabe, lau aldiz gutxienez, migratu dira holasteroideoak itsaso sakonerantz; horietatik hirutan Goi Kretazeoa eta Tertzia-rioaren artean. Stegasteridae (Duncan, 1889) familiakoak nagusitu ziren Goi Kretazeoko ur sakonetan baina, antza, Kretazeo/Tertziarioko trantsizioan galera handia pairatu zuten. Stegasteridae familiaren sistematika ez dago oraindik ongi finkatuta, beste arrazoiren artean, deskribatutako genero-tipoen hainbat espezieren eza-gutza ahula delako.Egun Euskokantauriar arro sedimentarioko (CVC hemendik aurrera, Cuenca Vasco-Cantábricaren siglak, hain zuzen ere) ekinidoen ezagutza eskasa da eta, bestalde, deskribapen urriko Rispolia subtrigonata (Catulo, 1827) izenarekin ekinido asko aipatzen dira, beti ur sakonekin lotuak, eremu eta adin geologiko oso ezberdi-nekoak, espeziaren aldakortasun handia aitzakia harturik, baina baliteke espezie ezberdinez aritzea; hori dela eta, beraien ezagutzan sakontzea bidezkoa dirudi.Rispolia Lambert,1917, generoa ez dela onargarria ondorioztatzen da Stegaster Pomel, 1883, generoaren ondorengo sinonimoa delako; eta baita espezie tipotzat Rispoliasubtrigonata hartzen duelako, zeina taxon bezala barne moldetan bakarrik oinarritzen denez zehaztasun, ezagupen eta irudikapen eskasekoa delako. Gauzak horrela, nomen dubium bezala hartu beharko litzateke, eta horrela ez jokatzean taldearen sistema-tikan nahasmen handia sortarazi du. Kontuan hartu behar da holotipoa galduta dagoela eta diagnosi-ezaugarri nagusiak agerian utziko zituen kalitatezko material faltagatik ezin izan dela deskribapen berririk egin. Iberiar penintsulako R. subtrigonata multzoan sailkatu den material guztia bi taldetan banatu daiteke: CVCn eta ziur aski baita Huescan eta Lleida aldean aurkitu direnak ere -azken hauek kontserbazio oneko aleak ez izanda ere- lan honetan deskribatzen den espeziari dagozkio. Berriz, Sistema Bético-ko eremukoak (Almeria, Murtzia, Alacant) Stegaster sp. espezie bati dagozkio, zeinean anbulakro pareak ez-petalodun agertzen diren eta sistema apikala luzatua, betiere, azterketa sakona osatzeko kalitatezko aleen falta izan.Stegasteridae familiaren diagnosia ere zuzendu eta biribildu egiten da lan honetan, genero berri bat deskri-batuz, Nafarroina, eta baita espezie berria ere, singularis, hain zuzen ere. Ondorioz, ur sakonetako Stegasteridae familiaren ezagutzarako ekarpena egiten da eta baita CVCko Echinoidea klasea hobe ezagutzeko ekarpena ere.Gako hitzak: Holasteroida, Stegasteridae, Nafarroina singularis taxon berriak, sakoneko faziesa, Coniaciarra, Euskokantauriar arroa.

  • English

    Currently, echinoids of the order Holasteroida Durham & Melville, 1957 live exclusively in the deep sea. In the Cretaceous some groups of holasteroids lived in shallower waters. Holasteroids have migrated to the deep sea at least four times independently, three of those times being between the Upper Cretaceous and the Lower Ter-tiary. The components of the family Stegasteridae Duncan, 1889 were the dominant deep-water holasteroids of the Upper Cretaceous, but they apparently underwent a major regression in the Cretaceous / Tertiary transi-tion. The systematic understanding of the Stegasteridae family is not yet fully established. One of the causes is insufficient knowledge of some type species of the genera described.

    Current knowledge of the echinoids of the Basque-Cantabrian sedimentary basin (BCB) is quite incomplete. On the other hand, many echinoids are cited under the name of Rispolia subtrigonata (Catullo, 1827), which was described in a very incomplete way, despite originating from different zones and ages, always from deep facies, taking refuge in the great variability of the species. It is very likely that there are different species among them and it is of interest to improve our knowledge about them.It is concluded that the genus Rispolia Lambert, 1917 is not valid, because it is a later synonym of StegasterPomel, 1883. Additionally, because it has as a type species, R. subtrigonata, which is an insufficiently described, understood and figurative taxon which, apparently, is only known from internal moulds, it should be consi-dered nomen dubium. This failure has contributed to a great deal of confusion in the group’s system. The holo-type is lost and it has not been possible to re-write with quality material, where all the diagnostic characters can be appreciated. It is considered that all the material that has been assigned to R. subtrigonata in the Iberian Peninsula can be classified into two groups. The fossils of the BCB and also, presumably in the absence of good specimens, those of the Lleida-Huesca area, correspond to the species described in this work. Those from the Betic area (Almería, Murcia and Alicante) correspond to a Stegaster sp., with no petaloid pairs ambulacres and elongated apical system, and which is pending study in the hope of obtaining specimens of sufficient qualityThe diagnosis of the family Stegasteridae has been amended and completed. The new genus Nafarroina and the new species singularis have been described. Therefore, a small contribution has been made to the improvement of the knowledge of the deep-sea family Stegasteridae and of the Echinoidea class, in general, to the BCB.