UHH - Geologisch-Palaeontologisches Institut (original) (raw)

3. Koevolution der Schnecken und der Mangrove, DFG Projekt (BA675/ 23)

Finished summer 2000 and continued especially regarding Neritimorpha.

In the project on Mangrove-Gastropoda our highlights were in the tracing of Potamididae-evolution from Late Cretaceous to the Recent, jointly with Thorsten Kowalke (now München). We were able to get some ideas of the paleobiogeography, starting out in the Eocene northern Tethys margin and splitting up into the modern Pazific, West African and Caribbean Provinces. We began the project with insights into coastal gastropods from the Cretaceous, which guided us to the questions of how they changed into the characteristic mangrove snails of out time.

Own papers here would be:

Bandel , K. & Riedel , F., (1994): The late Cretaceous gastropod fauna from Ajka (Bakony Mountains, Hungary). A Revision - Annalen des Naturhistorischen Museums, Wien. - 96A, S. 1-65, 1994.

Kowalke , T. & Bandel , K. (1996): Systematik und Paläoökologie der Küstenschnecken der nordalpinen Brandenberg-Gosau (Oberconiac/Untersanton) mit einem Vergleich zur Gastropodenfauna des Maastrichts des Trempbeckerns (Südpyrenäen, Spanien). Mitt. Bayer. Staatsslg. Paläont. hist. Geol., München - 15-71, 5 Pl., 10 Tab.

Bandel , K. & Kowalke , T. (1997): Eocene Melanotarebia n.g. and its relation among modern Thiaridae (Caenogastropoda: Cerithioidea). N. Jb. Geol. Paläont. Mh., H11, pp. 683-695, 10 figs., Stuttgart.

Abstract: Eocene Melanotarebia n.g. from freshwater-deposits of the coastal swamps of Gant/Hungary represents the oldest known member of the Thiaridae s.s. with an early ontogeny that took place in a brood pouch. Data concerning the morphology of the protoconch confirm a close relation to the Recent genera Melanoides , Tarebia and Sermyla . Thiaridae, thus, were present in Europe during the Eocene and could have originated here. Consequently migrating routes to Europe from the southeast since Late Miocene may represent a reestablishment of Thiaridae after they had disappeared from the region during the Late Oligocene.

Bandel , K. & Kowalke , T. (1999): Gastropod fauna of the Cameroonian coast. Helgoland Marine Research 53: 129-140.

Abstract: 18 species of gastropods were encountered to live near and within the large coastal swamps, mangrove forrests, intertidal flats and the rocky shore of the Cameroonian coast of the Atlantic Ocean. These represent members of the subclasses Neritimorpha, Caenogastropoda, and Heterostropha. Within the Neritimorpha representatives of the genera Nerita , Neritina , and Neritilia could be distinguished regarding their radula anatomy and eology. Within the Caenogastropoda representatives of the families Potamididae with Tympanotonus and Planaxidae are characterized by their early ontogeny and ecology. The Pachymelaniidae are recognized as independent group and are introduced as a new family within the Cerithioidea. Littorinimorpha as well as Neogastropoda ( Thais ) and Heterostropha ( Melampus and Onchidium ) are described and compared with representatives of the Caribbean and Indopacific province.

Bandel , K. (2001): The history of Theodoxus and Neritina connected with description and systematic evaluation of related Neritimorpha (Gastropoda). - Mitt. Geol.-Paläont. Inst. Univ. Hamburg, Heft 85, 65-164, 315 figs., Hamburg.

Abstract: Theodoxus and Neritina are distinguished from each other by their ontogeny. While the Theodoxus relation hatches from its spawn as miniature adult, Nertina and relation leaves its spawn as planktotrophic larva that will swim in the sea for a more or less extended period before its metamorphosis to a crawling young under the influence of fresh water. This difference in ontogeny can be recognized in the shape of the protoconch and history of both is traced to the Paleocene. Two subfamilies of the Nertininidae can, thus, be distinguished, namely the Neritininae n. subfam., and the Theodoxinae n. subfam. The Jamaican Fluvinerita has a place among the Theodoxinae and, therefore, the paleobiogeography of the Theodoxus relation is much enlarged. Today its species live in Europe, Northern Africa, and the Middle East. Among living species of Theodoxus systematic differentiation is difficult and when fossil representatives are included the taxonomic separation of species is even more problematic. An explanation for this is suggested in local hybridization, similar as is the case among modern species of Neritina occurring in the Indo-Pacific Ocean. Here transition between species are documented from Cebu (Philippines) and Bali (Indonesia) which include the “genera” Clithon as well as Neritina and its “subgenera”.

Interpretation of the evolution of the Neritoidea is not easy because of repeated convergence of shell shapes occurring at different times in different groups. Similar species as found among recent Neritoidea have been living in the tropical littoral zones in the Triassic and during the Jurassic species adapted to the environment of coastal swamps. The Neritidae became quite recognizable during the Cretaceous when smooth Dontostoma as well a spirally ribbed Nerita dwelled in tropical rocky littoral environments. A subdivision of the genus Nerita in subgenera is problematic since transitional species are the rule. Smaragdiidae have evolved mainly on and along with the marine sea grass. Their protoconch resembles that of the Paleogene Velatinae n. subfam. which evolved to quite characteristic shell shape and large shell dimensions. The Caribbean Puperita intermediates between Neritinae and Neritininae. Calyptronerita from the Eocene could represent an intermediate between Neritidae and Phenacolepadidae. Neritiliidae are an independent group that may be related to the Cretaceous Schwardtina and the terrestric Hydrocenidae, as is indicated when protoconchs are compared.

Neritoidea characterized by dissolution of their inner shell walls in the larval shell as well as in the adult shell demonstrate within their genera Theodoxus and Neritina holding many species the common occurrences of hybrids, and similar tendencies may be discovered among members of the genera Nerita and Smaragdia as soon as they become more closely inspected. The distinction of species is rather difficult due to the process of hybridization. Due to it a local geographic expresssion is produced and rapid historical changes in faunal composition are possible. A better understanding of this process can help in the interpretation of paleobiogeography as is documented by the differences seen in the faunal composition of Neritina varieties from Bali, Cebu and Natal/Madagaskar.