Cainozoic Research, 7(1-2), pp. 109-117, April 2010 A in between striking convergence conchological morphology Oligocene-Miocene lottiids (Mollusca, Patellogastropoda) from the North Sea Basin and the Paratethys Olga+Yu. Anistratenko¹Adri+W. Burger² & Vitaliy+V. Anistratenko³ 1 Institute of Geological Sciences ofNationalAcademy ofSciences ofthe Ukraine, O. GontcharaSir., 55-b, 01601, Kiev, Ukraine. E-mail: [email protected] 2 P. Soutmanlaan 18, NL-1701 MC Heerhugowaard, The Netherlands. E-mail: [email protected] 3 1.1. SchmalhausenInstitute ofZoology ofNationalAcademy ofSciences ofthe Ukraine, B. Khmelnitsky Str., 15, 01601. Kiev, Ukraine. E-mail: [email protected] Received 24 February 2009; revised version accepted 14 February 2010 The protoconch and teleoconchmorphology of Patella compressiuscala Karsten, 1849 (North Sea Basin, Chattian - Langhian) is de- The Boreobliniais established for this which is characterized indicative of scribed and illustrated. new genus species by a protoconch a lecithotrophic typeof early development, lacking even a short free-swimming larval stage. The distinctness ofBoreobliniagen. nov. from other Patellogastropoda such as Tectura,Patella, and Helcionexhibiting the typical patellogastropodprotoconch types is supported also by its unusual shell structure. An amazing heterochronous convergence ofboth protoconch and teleoconch morphology between the new species from the North Sea Basin and Miocene Flexitectura subcostata (Sinzow, 1892)from the Sarmatianofthe Paratethys is shown. Detailed descriptions and SEM images of species involved are presented. KEY WORDS:- Gastropoda, Lottidae, Miocene, Europe, protoconch, new genus Introduction marine gastropods with a planktotrophic larva in their on- togeny {e.g., Bandel, 1982, 1991; Sasaki, 1998; Kahn, 2004). The characters of embryonic, larval, and juvenile Oligocene and Miocene patellogastropods from the Medi- shells can be used to reconstruct the phylogeny of some terranean and Paratethys as well as from the North Sea the of the the gastropods. In case patellogastropods proto- Basin have usually been classified in different families, conch characters can reveal the size of the eggs and the such as PatellidaeRafmesque, 1815, Acmaeidae Carpenter, mode of embryonic development, e.g., the presence of a 1857, or Tecturidae Gray, 1847. The small-shelled repre- free swimming larva. sentatives ofthis group occur regularly but not abundantly For the first time a comparative study is presented between in various shallow to deeper marine and brackish water the minute Patella-like Patellacompressiuscala Karsten, habitats and were studied by many authors (Eichwald, 1849 that lived in the North Sea Basin from Chattian until 1830-1853; Karsten, 1849; von Koenen, 1882; Sinzov, Langhian time (Late Oligocene - Middle Miocene), and 1892; Friedberg, 1928); Kolesnikov, 1935; Jekelius, 1944; similar species known from the later Badenianand Sarma- Anderson, 1959;Baluk, 1975; Janssen, 1984; Il’ina, 1993; tian (Middle Miocene) from the Paratethys. The former Anistratenko, 2000, 2001; Harzhauser and Kowalke, exhibits unusual of which indicates an type protoconch, a 2002). of This of lecithotrophic type early development. type pro- Correct taxonomic identificationofthese species is some- toconch has been discovered before only in several species times difficult because the restricted number of concho- ofSarmatian lottiids from the Paratethys (see Anistratenko characters available and insufficient of logical knowledge also and discuss & Anistratenko, 2007). We present new the range of intraspecific morphological variation. Fur- data on the shell structure ofthe studied species. thermore, few data on protoconch morphology and type of For the Oligocene/Miocene species the new genus name early development ofthese gastropods have beenobtained Boreoblinia is proposed. Although the generic level of so far {e.g., Anistratenko et al., 2006; Anistratenko & taxonomic attributionofthe patellogastropods investigated Anistratenko, 2007). here requires further confirmation we assign them to the Protoconch ornamentation and shape are now generally family Lottiidae Gray, 1840 (for more detailed discussion useful taxonomic in accepted as characters, particularly see below under“Taxonomy”). - no- Figure I.Stratigraphic correlation chartof the standard scale (MediterraneanStages) with local stagesof the North Sea Basin, the Cent- ral and the Eastern Paratethys (Mediterranean Stages after Gradstein etal, 2004; CentralParatethys regional Stages afterHarzhauser & time in Mandic, 2008). The ranges ofPatellogastropods with a differenttype ofprotoconch shown vertical lines. — Figure 2. Localities, where studied materials were collected. 1 Miste, near Winterswijk, the Netherlands (local stage Hemmoorian, lower part ofthe Langhian); 2 - Pinnow, in the neighborhoodof Schwerin, Germany (“StembergerGestein”, Neochattian); 3 - Heist- op-den-Berg, located between Antwerp and Aarschot, Belgium (Zonderschot Sands, late Hemmoorian,early Langhian). - Ill - Material and methods Nomenclatural notes and taxonomy Our study is based on material from three localities in the Originally the species discussed was described as Patella North Sea Basin (Figures 1,2): compressiuscala and subsequently has been attributed to 1. Miste near Winterswijk (Gelderland province, the differentgenera: Acmaea Eschscholz in Rathke, 1833(e.g. Netherlands). It concerns a Middle Miocene fauna (local Kautsky, 1925), Scurria Gray, 1840{e.g. Anderson, 1959), stage Hemmoorian, lower part ofthe Langhian) from the Lepetella Verrill, 1880 {e.g., Janssen, 1984). According to Breda Formation that is described by Janssen (1984). At Waren(1972) the species belongs to the Cocculinacea and this lot of have been made for the Acmaeidae. locality a pits especially not to In our opinion Patellacompressius- fossil Six collecting. specimens came from the pit, made in calaKarsten, 1849 should be assigned to the family Lotti- the other six from several between idae it is 1968; come pits, dug Gray, 1840 as characterized by the sametype and 1968 and 1977. All provided by A.W. Burger. morphology of protoconch as Blinia Anistratenko, Bandel 2. Six specimens ofPatellacompressiuscala from theNeo- & Anistratenko, 2006 and Flexitectura Anistratenko, 2000 chattian “Sternberger Gestein” kindly provided by mr (more details see below). A.F.J. Jansen could be studied, collected near Pinnow in Since the publication ofKarsten (1849) the incorrectspell- the neighborhood of Schwerin (Schleswig-Holstein, Ger- ing “compress iuscula” has been generally used {e.g. Kaut- many). sky, 1925; Anderson, 1959; Janssen, 1984; Wienrich, 3. Also A.F.J. Jansen 18 “ provided by mr were specimens 2001), although the correct original spelling is com- from a” Heist-op-den-Berg (Brabant Province, Belgium), pressiuscal (Karsten, 1849: 12), and there is no nomen- where also several have been for fossil clatural it. in this risk pits dug collecting. reason to change Moreover, case the The material originates from the Zonderschot Sands, also of homonymy with Pileopis compressiuscula Eichwald, of late Hemmoorian(early Langhian) age. 1830 (though it is attributed to another genus - Tectura) is Adult shell characters were studied with an optical stereo- fortunately removed. microscope. Standard dimensionsfor shell characters were The distinct similarity ofthe protoconch and teleoconchof used. Morphological features of protoconchs such as P. compressiuscala with Flexitectura subcostata (Sinzov, shape, size, sculpture and character of boundary with the 1892) from the Middle SarmatianofUkraine and Moldova teleoconch were examined by means of scanning electron might be considered as evidence for their congenerity or of microscope (SEM). Altogether thirty-six specimens Pa- even conspecifity. However, there are some strong argu- tellacompressiuscala were analysed. Four specimens were ments against this attribution.First of all this Middle Sar- partially broken for SEM examination of the shell micro- matian lottiidwith a pancake-like protoconch is assumed to “ ” structure. be derived from the Early Sarmatian Tectura and might Most of the SEM obtained in the Institute of of of endemic mollusc images were represent one a large group genera Geological Sciences National Academy ofSciences ofthe of the Middle Sarmatian Paratethys basin (Kolesnikov, Ukraine (Kiev, Ukraine). Shells were mounted on stubs, 1935; Paramonova, 1994; Harzhauser & Kowalke, 2004; with and then documented sputter-coated gold using a lonesi et al., 2005; Anistratenko & Anistratenko, 2007). JSM-6490 Scanning Electron Microscope. A few addi- Noteworthy, the Early Sarmatian basin was already land- tional SEM micrographs ofshell structure were performed locked and immigrants from the Mediterranean or the in the Instituteand of North Basin Geological-Paleontological Museum Sea could not penetrate. The last occurrence the University of Hamburg (Germany); here the digital ofP. compressiuscala in the North Sea Basin predates the SEM LEO 1455 VP was used. All figured specimens are first occurrence ofBlinia andFlexitectura about2.5 Ma. If housed at the Institute of Geological Sciences National P. compressiuscala from the North Sea Basin and F. sub- of Sciences of the Ukraine would be attributed the Academy (Kiev, Ukraine), costata to a single genus mono- abbreviated IGS of as NANU. phyly the genus Flexitectura would become question- able. Hence, in spite ofa striking resemblance we treatthe Morphological terms for the shell description used