Schizogony in Dizerina anatolica Meriç

Abstract

Finding of the microspheric individual of Dizerina anatolica Meri9 containing 6 macrospheric embryos clearly indicates the presence of the schizogonic type reproduction in the Lepidorbitoididae. Location of the haploid macrospheric embryos within the test indicates the generation of these embryos in the rotaloid periembryonic part, and later, their movements toward the periphery of the test. INTRODUCTION The genus Dizerina was found, for the first time, in the vicinity of Koyulhisar (Sivas, Turkey; Meric 1978). In the examined thin-sections, one oblique-equatorial section of a rare microspheric individual was observed to have 6 macrospheric embryos. Two of those are located in the peripheral region of the test and four of them are located in the rotalloidally coiled periembryonic spiral. This situation, in other words, the schizogonic reproduction of the genus Dizerina, is observed for the first time. This individual, which was fossilized during the schizogony type reproduction, is one of the rarest samples of its kind. Presence of the schizogonic reproduction in benthic foraminifera has been noted by Cassan and Sigal (1961), Meriq (1966, 1970, 1973, 1976), Neumann and Poisson (1970) and Neumann (1972). As has been noted, the multinucleate microspheric individual produces the macrospheric embryos by means of dividing the cytoplasm (Grasse 1953). These macrospheric embryos move toward the periphery of the test by the dissolution of the chamber walls. Later, these walls are repaired. DESCRIPTION The individual of the Dizerina under consideration is a microspheric form. The diameter of this individual is 1.20mm in the oblique equatorial section. The rotalloidally-coiled periembryonic spiral forms roughly half of the test, as similarly seen in the macrospherical forms, and has a diameter of 800itm. Four of the macrospherical embryos are located in the periembryonic spiral and two are seen embedded into the lateral chambers (pl. 1, figs. 1, 2). In this section, it is observed that these are either protoconch or deuteroconch implying that these embryos are positioned differently. The width, height and the wall-thickness measurements are given in table 1. Some of the macrospheric embryos are located on the chamber walls of the periembryonic spiral, whereas the others are seen among the lateral chambers. This situation clearly indicates the enzyme activities secreted from the macrospheric embryos as similarly discussed in other cases of the schizogonic reproduction of the Orbitoidal foraminifera (Meriq 1966, 1970). By this activity, the chamber walls are dissolved and the macrospheric embryos move toward the periphery of the test. After the passage, the dissolved wall parts are repaired by CaCO3. TABLE 1 Measurements of the macrospheric embryos observed within the microspheric individual of Dizerina anatolica Meriq fossilized during the schizogony. Macrospheric Wall embryos Width (gum) Height(gim) thickness(jtm) 1 80 64 16 2 64 48 16 3 64 48 16 4 64 48 16 5 80 64 16 6 64 48 16 CONCLUSION This case of schizogonic reproduction in genus Dizerina is new evidence of the presence of the schizogonic reproduction stage of the Orbitoidal foraminifera as described by various authors (Cassan and Sigal 1961; Meriq 1966, 1970, 1973, 1976; Neumann and Poisson 1970; Neumann 1972). REFERENCES CASSAN, G. and SIGAL, J., 1961. Un cas de schizogonie intrathalame chez un Orbitoide. Bulletin de la Societe d'Histoire Naturelle de Toulouse, 96:153-156. GRASSE, P. P., 1953. Traite de Zoologie. Anatomie, Systematique, Biologie, 1(2), Paris. MERIR, E., 1966. A propos d'un cas de schizogonie dans un individu d'Orbitoides media (d'Archiac). Bulletin of the Mineral Research and Exploration Institute of Turkey, 67:93-96. , 1970. Schizogony in orbitoides apiculatus var. gruenbachensis. Micropaleontology, 16(2):227-232. ,1973. About the schizogony observed in the Discocyclina archiaci (Schlumberger). Revista Espafiola de Micropaleontologia, 5(3):403-408. , 1976. Bazi Ust Kretase ve Tersiyer bentonik foraminiferlerinde qogalma . I. T. U. Kiituphanesi, No. 1064, 1-89. , 1978. Dizerina, a new genus from the Upper Maastrichtian of northeastern Turkey. Micropaleontology, 24(1):97-108. NEUMANN, M., 1972. Sur les Orbitoidides du Cretace Superieur et du Tertiaire. II. Structure et classification. Revue de Micropaleontologie, 15(3):163-189. NEUMANN, M. and POISSON, A., 1970. A propos de la reproduction chez orbitoides media (d'Archiac). Revue de Micropaleontology, 13(2): 122-127. Manuscrip recieved August 15, 1991 Manuscript accepted December 3, 1991 micropaleontology, vol. 38, no. 3, pp. 313-314, plate 1, text-figure 1, table 1, 1992 313 This content downloaded from 207.46.13.146 on Tue, 23 Aug 2016 05:25:49 UTC All use subject to http://about.jstor.org/terms Engin Merif: Schizogony in Dizerina anatolica Meri? TEXT FIGURE 1 Index map of Turkey showing the location of the Koyulhisar area. Plate 1 2 Dizerina anatolica Meric 1 Oblique equatorial section of microspheric individual, containing 6 macrospheric embryos, x56. 2 Enlarged view of the macrospheric and microspheric embryos, ?105.