DFG Projekt (Ba 675/21/1-2) :
The cerithioideans of the coastal swamps and of fresh water lakes and rivers are analyzed according to their palaeontological history and their DNA composition. This later aspect has been analyzed by Ralf Bischoff from Bremen, who may assemble his data and may complete his doctoral thesis in the near future. We found a quite good fit between data on fossils back to the mid Cretaceous and grouping of Cerithioidea according to their DNA. The material for study comes from all parts of the world. Some of the most important results so far have been that there are at least four different lineages with which the Cerithioidea have moved from the sea into the fresh-water environment, and all the changes have apparently occurred already during Cretaceous time. The data allow to phrase some novel models on how fresh water populations evolved.
In this regard it has been very helpful to start a project on the coastal swamp and riverine gastropods in SE Asia, so far on Cebu Island with Frank Riedel, on Bali and Java. It also was of great value to have a collecting trip to Lake Tanganyika, Lake Malawi, and Madagascar, but also to visit Lake Baikal with Frank Riedel. Even though there are some similarities in general points between these two long existing lakes, the differences are considerable.
Published Papers:
Bandel, K.; Glaubrecht, M. & Riedel, F. (1997): On the Ontogeny, Anatomy, and Ecology of the Tropical Freshwater Gastropod Stenomelania (Cerithioidea, Thiaridae). Limnologia 27: pp 238-250.
Bandel, K. (1998): Evolutionary history of East African fresh water gastropods interpreted from the fauna of Lake Tanganyika and Lake Malawi. Zbl. Geol. Paläont. Teil 1: 233-292.
Abstract:
The long-lived Lake Tanganyika has a molluskan fauna that differs from other lakes in the area and from short lived lakes in general. Lake Malawi similar in shape, climatic conditions, size and depth has a different molluskan fauna. The radula and ontogeny of the endemic (thalassoid) gastropods of Lake Tanganyika reveal the presence of at least seven separate groups that probably represent monophyletic lineages derived from at least seven original immigrants to the lake: (1) the Paramelaniinae sensu stricu (with Paramelania ), (2) the Spekiinae n. subfam. with Spekia , Stormsia , and Bridouxia , (3) the possible Cleopatra relation around Reymondia , (4) the viviparous Lavigeriinae with the species of Lavigeria , (5) the minute sand- and thicket-dwelling Syrnolopsidae with Syrnolopsis , Anceya , and Martelia , (6) the Tanganyiciinae n. subfam. with Tanganyicia rufofilosa that has been described as having a brood pouch in the head-foot and would therefore represent a possible member of the Thiaridae, (7) the Neothauma group of viviparids. An eighth group has species living also outside of the lake with the basommatophoran Bulinus and Burnupia . A minute hydrobiid was newly discovered while the mostly monotypic genera Tiphobia , Mysorelloides , Limnotrochus and Chytra are thalassoid species, but were not encountered alive and may represent additional groups (probably two). While the radiation of fresh water caenogastropods characteristic of Lake Tanganyika has commonly been assigned to mainly one single family Thiaridae with exception of Neothauma , it has become evident that the thalassoid species are not monophyletic, but rather of polyphyletic origin. None of the species appear to be closely related to any of the species of the Thiarinae, even though the representative of this taxon, Melanoides is living in the larger tributaries of the lake. Neothauma appears to have been more widespread in the past, but with exception of the basommatophorans all others are restricted to actual Lake Tanganyika.
Lake Malawi in contrast, which appears to be of about four million years of age has no unique gastropod fauna that differentiates it from other lakes and even ponds and rivers of the region. The special fauna here has no endemic genera, and even the species here are the same or similar to those of the outside. Basically Lanistes , Melanoides , Bellamya and Gabbiella represent caenogastropods of the lake, and all four demonstrate a morphological spectrum which may represent a speciation still close to the founder, but could also represent only intraspecific variability. With exception of Gabbiella the founder species of all groups are also living in the lake. Comparison to fossil faunas of about two million years of age indicate that the fauna since then has little changed. A similar picture arises when fossil species found connected to the other lakes of the East-African Rift are compared with those of Lake Tanganyika. The fauna of the Lake Malawi type has been recognized here and their deposits ranging back into the Miocene, based on the genera Pila , Lanistes , Bellamya , Gabbiella , Cleopatra and Melanoides . It, thus, becomes evident that most of the gastropods that live in modern Lake Tanganyika have not come from these, but entered the lake during or prior to the Miocene and, thus, at least 5 million years ago when other genera dominated fresh water sources in Africa. A comparison of the described species with those known from Africa and described by Brown (1980, 1994) can be utilized to reconstruct a model of evolution of East African lake gastropods in Tertiary time.
Bandel, K. & Riedel, F. (1998): Ecological zonation of gastropods in the Matutinao River (Cebu, Philippines), with focus on their life cycles. Annls. Limnol. 34: 171-191.
Abstract: The tropical Matutinao River was investigated in respect of the question: what determines the distribution of the extant gastropods? Since ecological zonation and life-cycles are somewhat correlated, we followed both research avenues and in particular focussed on early ontogenetic strategies, which can be discriminated with the aid of detailed studies of corresponding shell features. With twenty-six gastropod species, almost all species which are distributed over whole Cebu Island occurred jointly in the small Matutinao River. The specific associations of river sections, and ecological demands and life-cycles of gastropods are characterized. Of special interest are planktotrophic neritoidean larvae, which are usually carried to the sea and develop in the marine environment, but in rare cases remain and successfully metamorphose in freshwater. The biogeographic background and evolutionary consequences of the results are discussed.
Bandel , K. (2000): Speciation among the Melanopsidae (Caenogastropoda). Special emphasis to the Melanopsidae of the Pannonian Lake at Pontian time (Late Miocene) and the Pleistocene and Recent of Jordan. – Mitt. Geol.-Paläont. Inst. Univ. Hamburg, Heft 84, S. 131-208, 176 figs., Hamburg.
Abstract: Melanopsis and the Melanopsidae can be traced to the Santonian (Cretaceous). Their closest relation among the Cerithioidea is with the Potamididae which remained in the coastal swamps, while Melanopsidae entered the fresh water. For ribbed Melanopsis like modern M. costata and smooth species like modern M. buccinoides record can be traced to the Cretaceous.
Alongside with unidirectional evolutionary change from one to the next species through an unknown amount of time the process of sudden and local hybridization plays a major role in the appearance of new species within the Melanopsidae. Hybrids occur in modern populations of Melanopsis living in the Jordan catchment and may be present among those that live in the Maghreb and Spain. Hybrids between the smooth species like Melanopsis buccinoides / praemorsa and the axially ribbed species like M. costata / tingitana and, in the western populations, also the spirally keeled M. dufouri may locally be common. A member of the M. dufouri group was still present in the early Pleistocene of the Orontes-Jordan area, but is no lo longer in existence here.
During late Miocene in Lake Pannon of the Paratethys basin even more species were involved in the hybridization process than today. Melanopsis. impressa , M. bouei , and M. kleini are known from the earlier Miocene. But also species regarded to represent members of other genera like Esperiana without posterior callus pad on the inner lip and record to the Cretaceous and Melanoptychia with a plication on the columella and unknown fossil record apparently mixed their genes with those of the obvious members of the genus Melanopsis within the vicinity of Lake Pannon.
The seven groups involved in hybridization recognized at Lake Pannon belong to the large sized Melanopsis impressa with angulated whorls, and the smaller smooth M. kleini , the tuberculous M. bouei , the ribbed M. oxyacantha , the small M. fuchsi with slender Esperiana -like shell, the keeled M. brusinai , and the Melanoptychia group with columellar plicae. The taxonomic treatment of melanopsids encountered in such meeting and hybridization places of two or more species resulted in many morphologically more or less distinct forms and, thus, numerous species names. Hybridization in differently mixed populations occurred at different times and places, sometimes with similar results regarding shell morphology, in other cases resulting in quite unique morphologies. Even though taxonomy is difficult, it is still evident that at different time slices since the Santonian the general shell characters within the melanopsids changed. For example Campanian, Eocene, late Miocene, Pleistocene and Recent melanopsids differ, even though some species appear very similar. The large lakes of the late Miocene Paratethys show a high diversity and displays different characters than are noted today, even though quite a number of relict species are still living. The latest large shift seems to have occurred in connection to the Messinian drying up of much of the Mediterranean Sea and, thus, the meeting of the catchment areas of rivers within the Mediterranean Basin. In its process two of the six groups from the Lake Pannon disappeared, while a few were greatly successful and developed several new hybridisation centers.
The oldest known ribbed Melanopsis is described as M. trempensis from the Campanian, and the genus Stilospirula from the Eocene is characterized.
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