Geo.Cro.2-3-61-KB.pdf 273 � 1. INTRODUCTION In the Izmir region (Western Turkey) near Bornova, Meso- zoic rocks are represented by the “wildfl ysch” zone of the Taurids consisting of a Maastrichtian-Danian sandy-shaly ma- trix with Late Triassic to Late Cretaceous carbonate mega- blocks. Previous work on the Mesozoic carbonates has been carried out by AKDENIZ et al. (1986), ERDOĞAN (1990) and ISINTEK et al. (2000). AKDENIZ et al. (1986) noted a thick carbonate sequence of Late Cretaceous age, tectonically overlying the Late Cretaceous clastics. ERDOĞAN (1990) reported that the Late Triassic to Late Cretaceous limestone masses in question were allochthonous blocks in the so-called “Bornova Melange” of Maastrichtian-Danian age. According to ERDOĞAN (1990) the carbonate block lying between the village of Naldöken and Çiçekli consists of Jurassic to Upper Cretaceous deposits, including an Albian bauxite lens north of Naldöken (Fig. 1). Recently the presence of a second baux- ite bearing horizon in the Barremian part of the upper lime- stone unit has been documented NE of Naldöken (Fig. 2). The Izmirella-bearing limestones are exposed in the so- called “Bornova-block” located between Naldöken and Çiçek- li (1:25.000, Izmir – L18 – b1 sheet; Figs. 1, 2). The studied Cretaceous deposits, north of Naldöken, are represented by a thick sequence of lagoonal, subtidal to supratidal limestones, Barremian–Lower Aptian in age and including a bauxite ho- rizon. The type section of the Izmirella-bearing limestones is located 250 m east of the Hendilagili Ridge, 2.7 km to the northeast of Naldöken (Figs. 1b, 2), and consists of a grey, thick bedded limestone sequence about 30 m thick (Fig. 3). The basal part of the section (about 10 m thick) consists of thick-bedded peloidal micrite and/or peloidal sparry facies, including laminated fenestral structures, intercalated with ter- restrial lime clays and palaeosols. The middle part of the section is made up of well bedded or nodular micritic and/or sparitic limestones, sometimes lami- nated, with pebbly or clayey micrite associated with early ero- sional surfaces. The clayey micritic limestones include rare foraminifera, gastropods, ostracods, faecal pellets, Salpingo- Baba Senowbari-Daryan1 and Ismail Isintek2 AB STRA CT Izmirella cretacea nov. gen., nov. sp., a complex alga, forming microbioherms is described from Barremian – Aptian platform carbonates of the “Bornova block”, an allodapic unit derived from the northern margin of the Menderes Massif, included in Maastrichian – Danian fl ysh deposits, called the “Bornova melange”. The verticillate thallus of this alga consists of strongly imbricated bowl- to funnel-shaped whorls having tightly stacked laterals with two lay- ers. The fi rst is composed of radially and fan-like running segments, appearing as large cells in section parallel to the growth direction. The second is composed of multibranched tubes, running perpendicular to the segments of the fi rst layer. Besides its organizational traits, this has original calcite mineralogy and an aggregative behaviour lead- ing to the formation of laminated build-ups closely resembling stromatolitic bioconstructions or even stromatopo- roids. Keywor ds: Algae, Izmirella, Cretaceous, Izmir, Turkey 1 GeoZentrum Nordbayern, University of Erlangen-Nürnberg, Loewenichstr. 28, D-91054 Erlangen, Germany; (basendar@uni-erlangen.de) 2 Department of Geological Engineering, Engineering Faculty, Dokuz Eylul University, 35100 Bornova, Izmir, Turkey; (ismail.isintek@deu.edu.tr) Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous, NE of Bornova-Izmir/Turkey Geologia Croatica 61/2–3 273–295 10 Figs. 7 Pls. Zagreb 2008 Geologia CroaticaGeologia Croatica � Geologia Croatica Geologia Croatica 61/2–3 274 Fi gu re 1: Location map of the study area in Western Turkey; (a) geological map of the Bornova area; (b) the position of the Izmirella nov. gen. bearing site (simplifi ed after ERDOĞAN, 1990). Fi gu re 2: Detailed geological map of the Mesozoic carbonates of the “Bornova block” in the area of the type locality of Izmirella nov. gen. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 275 Fi gu re 3: Type section of the Izmirella cretacea nov. gen., nov. sp. bearing limestone, in the upper limestone unit of the “Bornova block”. Geologia Croatica Geologia Croatica 61/2–3 276 porella (Hensonella?) dinarica RADOIČIĆ, large (2–25 cm) fragments of Izmirella microbioherms. Salpingoporella (Hen- sonella?) dinarica RADOIČIĆ is a paleobiogeographic marker of the Mediterranean Southern Tethyan margin (PEYBERNES & CONRAD, 1979), and has been reported from beds rang- ing from the Valanginian(?) (SCHINDLER & CONRAD, 1994) or from the Tithonian?–Berriasian (GRANIER, 2002) to Late Aptian (VELIĆ & SOKAČ, 1983). Its acme is in the Barremian–Lower Aptian (LUPERTO SINNI & MASSE, 1993). The upper part of the type section with Izmirella cretacea nov. gen., nov. sp. is characterized by bioturbated, thick bed- ded or laminated micritic and/or intra-pelsparitic limestone with laminated fenestral structures, and thick bedded nodular micritic limestone. 2. SYSTEMATIC PALAEONTOLOGY Alga incertae sedis Genus Izmirella nov. gen. Derivatio nominis: After the city of Izmir, close to which the alga was found. Diagnosis: Thallus segmented, composed of strongly im- bricated bowl- to funnel-shape whorls, each with tightly stack- ed, septate laterals. Laterals, appearing as an oval or rectan- gular cell layer in sections, are divided radially several times towards the periphery of the whorls. A multibranched cell lay- er originates from the upper surface of the laterals, forming a second layer of whorls. A third layer consisting of “chaotic” tubes is located between the individual layers of the thallus. Calcifi cation was originally calcitic. The organism grew with successive rows of closely packed individuals forming domal, laminated thalli resembling stromatolites or even stromatopo- roids. Type species: Izmirella cretacea nov. sp. Izmirella cretacea nov. sp. (Figs. 4–10; Pls. 1–7) Derivatio nominis: After the occurrence of the alga in the Cretaceous deposits. Holotype: Longitudinal section illustrated in Pl. 4, Fig. 1. Isotypes: All specimens illustrated in Pls. 1–7. Locus typicus: 2.7 km northeast of Naldöken, 250 m east of Hendilagili Ridge, Karaburun/Turkey (see Figs. 1–2). Stratum typicum: Lower Cretaceous (Bar remi an–Aptian) Diagnosis: Because of the monospecifi c character of the alga, the species diagnosis corresponds to the diagnosis of the genus. Material: Four microbioherms contain numerous hemi- spherical laminae. From one microbioherm containing the hol- otype (Pl. 4, Fig. 1) three large thin sections (10´15 cm) and from the second microbioherm two large thin sections were made. Depository: The holotype (5 thin sections and 4 rock pieces) and illustrated paratypes are kept in the Forschungs- institut und Naturmuseum Senckenberg/Frankfurt a. M., Ger- many, Inventary-Nr: microbioherm of holotype (rockpieces: SM.B. 20863/a–c, thin sections illustrated in Pls. 1–4: SM.B. 20863a/1, 20863b/1, 20863c/1, 20863d/1, 20863e/1), and one paratype SM.B. 20864 illustrated in Pl. 5. Description of microbioherms Izmirella cretacea nov. gen., nov. sp. forms bioconstructed bo- dies up to 22 cm high which resemble stromatolites or stro- matoporoid sponges with distinct laminations (Pl. 1, Figs. 1– 4; Pl. 2, Figs. 1–2; Pl. 3, Fig. 1). The individual laminae (layers) of the outside of the bioherms correspond internally to the individual rows, which are formed by numerous thalli of Iz mirella cretacea arranged one beside the other (Pl. 2, Figs. 1–2). In thin sections, individual laminae are separated by dark horizons, usually thinner than the layers of Izmirella rows (Pl. 2, Figs. 1–2). These dark horizons are composed of small and multibranched tubes of “chaotic” arrangement (Pl. 5, Figs. 5, 8) resembling Girvanella. These tubes will be described in detail under the description of Izmirella. The microbioherm containing the holotype is tabular, up to 7 cm thick with a height of 14 cm and a lateral extent of 21 cm (before cutting). Another microbioherm (Pl. 1, Figs. 1–4), showing the height (Figs. 1–2), thickness (Fig. 3) and lateral extension (Figs. 1–2), is also tabular, reaching 5.5 cm thick- ness, 22 cm height and 22 cm width. The microbioherm containing the holotype exhibits the well-developed lamination on one side only but the paratype, illustrated in Pl. 1 shows well developed lamination on both sides. The base of this microbioherm is bulbous and shows several circular shaped initial parts of individual thalli of Iz- mirella, having a diameter of approximately 2 mm. Each basal bulb consists of the individual thalli of Izmirella cut in cross section (see Pl. 2, Fig. 1 upper part of the photograph). The outer surfaces of all four available microbioherms are lamellar. The height of individual laminae is almost con- stant (about 3 mm, rarely varying between 2 mm and 5 mm). The laminae in the basal part of two microbioherms extend laterally, parallel to the substrate but in the younger part they are almost sub-spherical. In the third microbioherm the lami- nae at the top also extend parallel to the substrate (Pl. 1, Figs. 1–2). This specimen seems to be broken at both sides. The top of all microbioherms are vaulted. Description of Izmirella cretacea nov. gen., nov. sp. Three large thin sections (10x15 cm, two parallel and one trans- verse to the growth direction) were cut into the microbioherm containing the holotype. Two large thin sections were made from the second microbioherm. The longitudinal sections show (as recognizable from the outside), the layers (laminae) reaching a height of about 3 mm (Pl. 1, Figs. 1–4; Pl. 2, Figs. 1–2; Pl. 3, Fig. 1). Each laminae is composed of numerous thalli of Izmirella, arranged in rows one beside the other (Pl. 2, Figs. 1–2; Pl. 3, Fig. 2). Adjacent thalli are in contact (especially at their lower and middle parts), but they never amalgamate laterally. Individual thalli reach a diameter of 2.5–4.5 mm (Pl. 3, Figs. 2–4; Pl. 4, Figs. 1, 4, 6; Pl. 5, Fig. 1, 3; Pl. 6, Figs. 1, 4). Most thalli have the same length corresponding to the height of laminae. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 277 Each thallus is composed of numerous soup-plate- or bowl- to V-shaped elements or segments (Pl. 2, Figs. 1–2; Pl. 3, Figs. 2–4; Pl. 4, Figs. 1–2, 4–5; Pl. 5, Figs. 1, 3; Pl. 6, Fig. 1, 4), termed whorls in this paper. The whorls are fi tted one above the other. At the basal part of the thalli, the individual whorls are usually soup-plate-like, at the middle they become more bowl-like, at the upper part the whorls are mostly V- shaped in section with a wide collar (Pl. 3, Fig. 3; Pl. 4, Figs. 1, 4–5), U-shaped (Pl. 3, Fig. 4), or even cup-shaped (Pl. 6, Figs. 1, 4, 8). In some specimens the bowl-shaped whorls of the middle part are less steep and resemble the soup-plate shaped whorls of the basal part, which they partly overlap (Pl. 5, Fig. 3). The inside of the youngest whorl is fi lled with ei- ther secondary calcite cement (Pl. 2, Figs. 1–2; Pl. 3, Fig. 2; Pl. 7, Fig. 7) or a micritic fi lm which covers the inside of the whorl (Pl. 3, Fig. 4). Micrite also fi lled part of the inside of the whorl (Pl. 4, Fig. 2; Pl. 6, Figs. 4, 8). The micritic fi llings do not show any geopetal fabric and are interpreted to be of organic origin. Spherical elements of about 50 µm in diameter were observed within this micritic mass (Pl. 6, Fig. 12). Inter- pretation of these spherical elements as reproductive organs (gametangia) is very speculative. In longitudinal sections (parallel to the axis of the thallus) the individual whorls exhibit two layers of “cell-like” struc- tures (Pl. 4, Figs. 2–3, 5–6; Pl. 5, Figs. 1–4, 6; Fig. 4). The basal layer is composed of “large cells” corresponding with what we assume to be “laterals” (analogous to the thallus or- ganization of dasyclad algae) cut in cross sections, arranged radially and running from the centre to the periphery of the whorls, similar to Recent Acetabularia (Pl. 3, Figs. 5–6; Pl. 4, Figs. 2–3, 5–7; Pl. 5, Figs. 1–4, 7; Pl. 6, Figs. 2–3, 5, 10–11, 13; Pl. 7, Figs. 1–2.). In cross section, the outline of the laterals (“large cells”) is oval to quadratic in shape, normally 80x40 µm directly around the axial column, termed here as the “ax- ial stem” (Pl. 4, Figs. 2–3, 6; Pl. 5, Figs. 1, 3, 6; Pl. 6, Figs. 2, 5; Fig. 4 marked with number 1). As observed in tangential sections, the laterals are divided several times toward the pe- riphery of the whorls, by a zig-zag (wavy), thin wall (Pl. 3, Figs. 5–6; Pl. 4, Fig. 7; Pl. 5, Figs. 1–3, 7; Pl. 6, Figs. 10–11, 13; Pl. 7, Figs. 1–2; Figs. 5–6). At least fi ve divisions and six orders of laterals were commonly observed (Fig. 7). As shown in Fig. 7, the levels where the laterals divide are not exactly at the same horizons. The divided pattern of the “laterals” of Izmirella resembles some porostromate calcareous algae, like Hedstroemia, Selonopora or Palaeozoic genera including Boto- maella or Halysis (compare RIDING & VORONOVA, 1985, fi g. 6; MUNNECKE et al., 2001, fi g. 9; FLÜGEL, 2004, pl. 98, fi g. 2). Such dichotomy of the “laterals” was also observed in the dasycladalean genus Campbelliella (see DE CASTRO, 1993, pl. 13). The second layer, which appears darker in transmitted light, is developed above the fi rst and is composed of tubes originating from the upper surface of the laterals (Pl. 4, Figs. 3, 6; Pl. 5, Figs. 2, 4; Pl. 7, Fig. 1). If the section passes through the upper surface of the laterals, they appear as a plate of pores, refl ecting the cross sections of the tubes (Pl. 3, Figs. 5–6; Pl. 7, Fig. 1; Figs. 4, 6). We term this layer with its correspond- ing tubes as “tubes of the second layer”, interpreted as having originated by multi-branching from different portions of the “laterals” (Pl. 4, Figs. 3, 6; Pl. 5, Figs. 1–4; Pl. 6, Fig. 6). The transverse outline of these “tubes” is usually polygonal, or somewhat circular, with a diameter of approximately 10 µm (Pl. 5, Figs. 2, 4, 6,). The resulting pattern consists of a layer of tubes between two layers of laterals (Pl. 4, Figs. 2, 3, 6; Pl. 5, Figs. 1–4, 6; Pl. 6, Fig. 3; Pl. 7, Figs. 1, 7–8), which repre- sent off shoots? of Izmirella and may be erroneously inter- preted as representing another alga. As mentioned above, the darker horizons between the in- dividual laminae (Pl. 2, Figs. 1–2; Pl. 3, Fig. 1) are composed of a “chaotic” cell layer, similar to Girvanella (Pl. 4, Fig. 7; Pl. 5, Figs. 5, 8). As observed in several specimens, the edge of the last whorl becomes trumpet-like from which the “chaotic” Fi gu re 4: Section through three layers of laterals appearing white in thin sections (1) and three layers of tubes of second layers appearing dark in thin sections (2). The upper right corner of the photograph corresponds to the upper surface of laterals, from which the tubes of second layer (2) originate. The centre of the thallus is located in the NE, outside of the drawing. Redrawn from Pl. 5, Fig. 2. Fi gu re 5: Section exhibiting the radiating branching pattern of the laterals from the axial stem. From seven laterals at the base (from the “axial stem”), about 40 laterals originate in the periphery of the whorl. Geologia Croatica Geologia Croatica 61/2–3 278 PLATE 1 1–4: Microbioherm (paratype) formed by Izmirella cretacea nov. gen., nov. sp. Scale: 1 cm. 1 View of the “front-side” of a paratype showing the well-developed wavy laminae oriented parallel to the substrate (for magnifi cation of laminae see fi g. 4). 2 View of the other side (“back-side”) of the same specimen illustrated in fi g. 1. 3 Side-view of the same specimen illustrated in fi g. 1 or fi g. 2. 4 Magnifi ed part from Fig. 1 (quadrangle marked with white line) shows details of the lamination. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 279 Geologia Croatica Geologia Croatica 61/2–3 280 PLATE 2 1–2: Izmirella cretacea nov. gen., nov. sp. 1 Magnifi cation from thin section 1q (transverse to oblique section) showing three layers (correspond to the laminae, separated by dark area containing “chaotic tubes”) in which the individual thalli are arranged in rows one beside the other. In the lower part of the photograph the thalli are cut in longitudinal section exhibiting the individual soup-plate-, bowl- or funnel-shaped whorls arranged one above the other. At the upper part of the photograph the thalli are cut obliquely or transversely, exhibiting the circular outline of the whorls in cross section. 2 Magnifi cation from thin section 1/l showing the rows (layers or laminae), in which the individual thalli are arranged one beside the other. The dark areas between the layers of adjacent thalli contain small “chaotic tubes”. The youngest whorl of the thallus is usually fi lled with calcite cement. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 281 Geologia Croatica Geologia Croatica 61/2–3 282 PLATE 3 1–7: Izmirella cretacea nov. gen., nov. sp. Scale in Fig. 1 is 2 cm, in all others 1 mm. 1 Longitudinal section (parallel to the growth direction) of a microbioherm containing the holotype (see Pl. 4, Fig. 1) exhibits the individual layers (laminae) composed of numerous thalli of Izmirella arranged in rows one beside the other in horizontal direction (thin section 1/l). 2 Magnifi cation from fi g. 1 showing several thalli with bowl- or funnel-shaped whorls. The interior of the last whorl is usually fi lled with calcite cement. Thin section1/1. 3 Magnifi cation from fi g. 1. View of a thallus showing the plate-like and relatively broad whorls at the lower part (right in photograph) and V-shaped whorls at the upper part (left in photograph) of a thallus. Thin section 1/1. 4 Section through the younger part of a thallus that exhibits the cup-shaped last whorl. From the upper part of the youngest whorl there appears to arise a new whorl or a new thallus(?). The interior of the last whorl is covered by micrite of organic origin; the remainder is fi lled with calcite cement (for details see Fig. 10). 5 Longitudinal section through a thallus showing the “laterals” of the fi rst order (small arrows), branching to the “laterals” of the second and higher orders. The large triangular arrows indicate the radially arranged “laterals” of the fourth order. The medium-sized triangular arrows indicate the polygonal outline of the “tubes of the second layer” running perpendicular to the “laterals” of fi rst and second order. The small triangular arrow indicates the axial stem connecting the individual whorls. The large arrows at the left of the photograph indicate the branching pattern of the “tubes of the second layer” from the upper part of the “laterals”. Note the wavy (zig-zag-like) wall between the “laterals” of fi rst and second orders (compare fi g. 7). Thin section 1/1. 6 Similar to fi g. 5. Longitudinal section through four whorls exhibiting alternating “laterals” and the polygonal outline of the “tubes of the second layer” which are cut in transverse section and run perpendicular to the “laterals”. Note the wavy (zig-zag-like) wall between the “laterals”. Thin section l/q. 7 Section exhibiting the edge of the last whorl of a broad, trumpet-like form, from which the tubes of the second layer originate (for details see Fig. 8). Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 283 Geologia Croatica Geologia Croatica 61/2–3 284 PLATE 4 1–7: Izmirella cretacea nov. gen., nov. sp. All fi gures are from the same microbioherm as the holotype (thin section 1/l, Pl. 3, Fig. 1). Scale in all fi gures 1 mm. 1 Holotype. Axial longitudinal section showing numerous soup-plate to bowl- to funnel-shaped whorls. The narrow axial stem is cut in the upper and lower parts of the whorl. Thin section 1/1. 2 Section through a thallus exhibiting several whorls with the axial stem cut in the centre of the last four whorls. Tubes of the second order, originating from the edges of the last whorl, extend bridge-like between the edges of the last whorl. The interior of the last whorl is covered by micritic layer (black) of organic origin. “Up” is toward the left. 3 Magnifi cation of several whorls showing the “laterals” (appearing as large cells) passing to the small, branched tubes (“tubes of second layer”) which have arisen from the laterals of fi rst order (arrow). “Up” is toward the left. 4 Magnifi cation of a thallus showing the bowl-like whorls at the lower part (right in photograph) and funnel- or V- shaped at the upper part (left in photograph) of a thallus. The small arrow indicates the radially arranged and fan- like multibranched tubes of the fi rst order of “laterals” (longitudinal section). “Up” is toward the left. 5 The “laterals” of the fi rst and second order are recognizable in the last funnel-shaped whorl. The axial stem is cut in the centre of the preceding three whorls. “Up” is toward the left. 6 Similar to fi g. 5. The large arrows indicate the branching pattern of the “tubes of the second layer” and the triangu- lar arrow points to the branching of a “tube of the second layer”. 7 Transverse to oblique section through several whorls. The arrows indicate to the fan-like radially branched fi rst, second and third order “laterals”. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 285 Geologia Croatica Geologia Croatica 61/2–3 286 PLATE 5 1–8: Izmirella cretacea nov. gen. nov. sp. from the third microbioherm. Scale in fi gs. 1 and 3 is 0.5 mm, in fi g. 6 is 0.1 mm, in all others 0.2 mm. 1 Section through several whorls of a thallus exhibiting the laterals and the tube layers of second order. The laterals appear as rectangular cells in the middle part, becoming oval and tube-like to the periphery of the whorls. The fan- like branching of the laterals is recognizable in the last whorl (for details see fi gs. 2, 4). 2 Magnifi cation from fi g. 1 shows the details of three whorls with laterals (light area) and the tubes of a second layer (dark area). The fan-like branching of the laterals of the last whorl is clearly recognizable. The dark area with some pores at the last whorl (upper right) shows the boundary between the laterals and tubes of the second layer. Arrows indicate the origin of the tubes of the second layer from the laterals (for details see Fig. 4). 3 Section through the upper part of a thallus exhibiting individual whorls running down and covering the old whorls. The axial stem is cut at the upper part, continuing to the fan-like branched laterals. 4 Similar section to fi g. 2 showing the same characteristics. Arrows indicate the detailed origin of the tubes of the second layer. 5 Cluster of “chaotic” cells originating from the laterals (white area with large “cells”). 6 Two “cell” layers of laterals (large “cells”) and tubes of the second layer (small “cells”) in an isolated fragment of a thallus. 7 Fan-like branching of the laterals as shown in fi g. 7. 8 Formation of “chaotic” tubes from the second layer (2) of the whorl. White “line” (1) indicates the laterals. Arrow indicates the origin of the “chaotic” tubes. C = the cavity within the “chaotic” tubes. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 287 Geologia Croatica Geologia Croatica 61/2–3 288 PLATE 6 1–13: Izmirella cretacea nov. gen. nov. sp. from the third microbioherm. 1 Section through two thalli each with numerous whorls. The interior of the last whorl in the thallus on the left is fi lled with calcite cement. The axial stem is cut in the lower part of the thallus on the right. For details see fi g. 2. 2 Magnifi cation of the area in fi g. 1, marked with white rectangle, showing numerous whorls with the laterals appearing as rectangular cells (lower part) adjacent to the axial stem. The axial stem passes through the whorls and branches at the upper most part (see fi g. 3). 3 Magnifi cation of the upper most part of the axial stem in fi g. 2 showing the branching pattern. The laterals appear gray (partly as a cell layer); the tubes of the second layer are darker. Small arrows indicate the branched tubes of the second layer. 4 Section through a thallus with a cup-shaped fi nal whorl. The edge of the last whorl (quadrangle, see fi g. 7) expands (trumpet-like), with the later rejuvenation above. The interior of the last whorl is fi lled partly with micrite (gray) of organic origin. Numerous small spherical elements (gametangia?, barely recognizable, see fi g. 12) are embedded within the micritic fi lling. 5 Section from the upper part of a thallus showing the laterals and the branching pattern of the axial stem at the upper end of the thallus (for details see fi g. 6). 6 Magnifi cation of fi g. 5 showing the details of the axial stem. 7 Magnifi cation from fi g. 4 (quadrangle) showing the trumpet-like broadening of the upper end of the last whorl. 8 Section through the upper part of a thallus showing the interior of the last whorl fi lled partly by micrite (gray) of organic origin and partly by cement (white). Numerous spherical elements (gametangia?) are embedded within the micritic fi lling. Cluster of tubes (appearing as cells) connect (like a bridge) the outer edges of the last whorl (for details see fi g. 9 and 12). 9 Magnifi cation of part of fi g. 8, (large rectangle) of cells originating from one end of the whorl connecting both edges of the last whorl. 10 Cross section through two thalli showing the last whorls appearing concentric (bulbous) with numerous laterals. Arrow indicates the details of the last whorl in fi g. 11. 11 Magnifi cation from fi g. 10 (arrow) showing the rejuvenation (?) of a whorl from a lateral and the branching pattern of the laterals. 12 Magnifi cation from fi g. 8 (small rectangle) shows the tubes (right in photograph) and numerous spherical elements (gamentangia?) within the micrite infi lling. 13 Magnifi cation of the upper part of the specimen illustrated in Pl. 5, Fig. 3 showing the origin of the whorls and laterals from the axial stem (white area) and the tubes of the second layer that originated from the laterals (dark area). Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 289 Geologia Croatica Geologia Croatica 61/2–3 290 PLATE 7 1–8: SEM-photomicrographs from diff erent parts of Izmirella cretacea nov. gen., nov. sp. 1 Section through three layers of laterals and tubes in a second layer. White arrows indicate the tube-like laterals. Tubes of the second layer originate from the “pores”, in the upper surface of laterals. For magnifi cation of the area marked with rectangle marked see fi g. 2. “Up” is toward the left. 2 Magnifi cation from fi g. 1 (rectangle) showing the inside of laterals fi lled with large calcite crystals (arrows) and the wall of the laterals characterized by microgranular micritic crystals. For magnifi cation of the area marked with a rectangle see fi g, 3. “Up” is toward the left. 3 Magnifi cation from fi g. 2 showing the laterals, characterized by large crystals, and the wall characterized by microgranular structure of the crystals. “Up” is toward the left. 4 Magnifi cation from fi g. 7 showing the laterals with large crystals. Arrows indicate the wall of laterals branching to the tubes of the second layer. “Up” is toward the left. 5 Similar to fi g. 3. “Up” is toward the left. 6 The interior of laterals is characterized by large crystals and the walls (arrows) by microgranular structure. The area within the dots points to the tubes of the second layer that originated from one lateral. “Up” is toward the left. 7 SEM-view of alternating laterals (large crystals) and tubes of the second layer (small crystals). Arrow indicates the last whorl fi lled with calcite cement. “Up” is toward the left. 8 Alternation of laterals and tubes of second layer. Arrows indicate their boundaries. “Up” is toward the left. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 291 Geologia Croatica Geologia Croatica 61/2–3 292 Girvanella-like tube layer originates (Pl. 3, Fig. 4; Pl. 5, Figs. 5, 8; Pl. 6, Figs. 4, 7; Fig. 8). The edges of the last whorl in some specimens are connected by a layer of tubes, forming a lid (appearing as a bridge between the edges) covering the top of the whorl (Pl. 3, Fig. 4; Pl. 4, Fig. 2; Pl. 6, Figs. 8–9; Figs. 9–10). Apparently the repetitive settlement of the alga results from these tube layers originating from the edges or lids of the last whorl. In most cases one or several calcite-fi lled cav- ities were observed within the clusters of the “chaotic” Gir- vanella-like tubes (Pl. 5, Fig. 8). Interpretation of these cavi- ties as conceptacles is very speculative. The most peculiar part of this alga is the axial stem con- necting the whorls of the thallus (Pl. 4, Figs. 1–2, 5; Pl. 5, Fig. 3; Pl. 6, Figs. 1–6, 10–11, 13). The axial stem is very narrow (less than 1 mm; usually 0.40–0.80 mm). Numerous sections show that the axial stem is a part of this alga and can not be interpreted as a boring or as an interaction between the alga and another organism (symbiosis or commensalism; like a worm, etc.). The following criteria support this interpretation: a) the axial stem is always in the centre of the whorls and the whorls are arranged symmetrically around it; b) the cements of the axial stem continue into the whorls and there is no re- cognizable boundary between them (Pl. 6, Figs. 3–6, 11–13); c) the laterals of the last whorl originated from the branching of the axial stem and the axial stem does not possess its own wall (Pl. 6, Figs. 2–3, 4–5, 10–13); d) the axial stem never steps out over the last whorl. The holotype (Pl. 4, Fig. 1) exhibits numerous bowl- to V-shaped whorls in longitudinal section, showing only some of the characteristics of Izmirella cretacea summarized from the paratypes. The holotype is composed of at least 20 whorls. The axial stem is cut through several whorls. A reconstruction of a half-whorl of Izmirella cretacea nov. gen., nov. sp. is giv- en in Fig. 6. Rejuvenation of the thalli usually takes place at the bound- ary between two laminae (Pl. 2, Figs. 1–2; Pl. 3, Figs. 2, 4, Pl. 4, Fig.4). This boundary is marked by a dark horizon where individual whorls, at the base of the thalli, are usually develop- ed as a soup-plate pile arranged densely one above the other. 3. DISCUSSION Izmirella cretacea nov. gen., nov. sp. is a representative of fossil plants, most probably algae. However, because of the totally different characteristics, its systematic classifi cation within the known groups of algae is uncertain. In longitudinal sections, (parallel sections to the growth direction), through the thalli of Izmirella-buildups, the indi- vidual laterals appears as cell rows, resembling some red algae (Rhodophycea) with “large cells”, e. g. representatives of the genus Lithoporella (FOSLIE) or Titanoderma NÄGELI (com- pare WRAY, 1977, fi g. 58; RASSER, 1994; PILLER & RASS- ER, 1999). Izmirella may be ascribed to such algae if its thal- lus is fractured (Pl. 5, Fig. 6). In thin-sections of Izmirella, the “large-cell”-like structures (similar to Lithoporella), are in re- ality the radially arranged (similar to representatives of Mod- ern Acetabulariaceae) “laterals” cut in cross section. Cells with different sizes and arrangement may occur in some red algae, e. g. in crustose coralline red algae Phymatolithon calcareum and Lithothamnium coralloides (ADEY & MCKIBBIN, 1970) or in recent genus Tenarea (WRAY, 1977, fi g. 54). Laterals in Izmirella are, however, segments that are arranged as in the cups of Recent dasycladales Acetabularia – radially around the axial stem, which is not known from red algae. The radially arranged “laterals” and the axial stem con- necting the successive whorls is a common feature of the Dasycladales, family Acetabulariaceae (see BERGER & KAE- VER, 1992). In this group, individuals are usually isolated; the gregarious potential and the ability to build small bio- herms, as in Izmirella are very rare in the fossil record. Neo- Figure 6: Reconstruction of a half whorl of Izmirella cretacea nov. gen., nov. sp. showing the radially arranged “laterals” that are subdivided internally and peripherally to laterals of the second and higher orders (compare also Fig. 7). From the pores of the upper surface (shown in third lateral from left) open into the cross-sections of “tubes of the second layer” which are oriented perpendicular to the laterals of fi rst and higher orders. Schematic, not to scale. Figure 7: The branching pattern of the laterals of the fi rst, second and further orders (6 orders, see numbers) of the whorls. The branching doesn’t occur at exactly the same level. The wall between the tubes is zig-zag-like (wavy). Schematic, not to scale. Geologia CroaticaBaba Senowbari-Daryan and Ismail Isintek: Izmirella cretacea nov. gen., nov. sp., a complex alga from the Lower Cretaceous... 293 teutloporella BASSOULETT et. al. is the only representative (BASSOULETT et. al., 1978) of gregarious (numerous thalli growing one beside the other) dasycladales occuring in the Oxfordian–Tithonian according to GRANIER & DELOFFRE (1993) or Oxfordian–Berriasian according to SCHLAGINT- WEIT & EBLI (1999). For instance in the Upper Jurassic reef facies of Sicily, this alga is very abundant in nodular micro- bioherms up to 30 cm in diameter (SENOWBARI-DARYAN et al., 1994). The following features might support the affi liation of Iz- mirella to the Dasycladales: a) Each thallus possesses an axial stem which passes through the individual whorls (Pl. 4, Figs. 1–2, 5; Pl. 5, Fig. 3; Pl. 6, Figs. 1–6, 13). The axial stem with a diameter of 40–80 µm, however, is extremely narrow to bear the weight of laterals with a diameter of about 3 mm, but the Recent Acetabularia also possesses a narrow stalk. It may be assumed that the ar- rangement of the thalli in rows and their growth strategy in Izmirella, i. e. one beside the other, could help to support the individual thalli in growth position. b) The arrangement of the “laterals” is comparable with the rays (laterals) from caps of Recent Acetabularia, Polyphy- sa or Chalmasia, radiating around the axial stem (see BERG- ER & KAEVER 1992, fi gs. 3.56, 3.81, 3.91), c) The segments, i.e. whorls, are arranged vertically around the axial stem, one above the other. d) The microbioherms are composed of individual stacked thalli of Izmirella. Notwithstanding these apparent similarities, the verticil- late organisation of the whorls around the axial stem and the septate nature of the laterals, do not conform to the features of the Dasycladales (BERGER & KAEVER, 1992). The fol- lowing features of Izmirella argue against its assignment to Dasycladales: a) Calcite mineralogy of skeleton: The primary skeletal mineralogy of the Dasycladales is aragonite; primary calcite in Dasycladales is extremely rare. Minor amounts of calcite do occur in some Dasycladales e. g. in Bornetella (FLAJS, 1977), and the membranes around the laterals of Clypeina jurassica (FAVRE) are composed of Mg-calite (CONRAD & VAROL, 1990). Similarly, the sporangia within the axial stem in Diplo- pora iranica (SENOWBARI-DARYAN & HAMEDANI, 2000) were primary Mg-calcite, but a primary Mg-calcite mineralogy for the thallus of Dasycladales is not known. The systematic position of some dasyclad type organisms, e. g. Palaeozoic Psedo vermiporella ELLIOT, as Dasycladales is uncertain (FLÜGEL, 2004). Therefore, the primary calcite mineralogy of Izmirella does not support its classifi cation as a dasycla- dalean. b) The branching pattern of the “tubes of the second layer” is similar to porostromate cyanophyceans like Cayeuxia, Hed- stroemia or Halysis mentioned above. However, such struc- tures, originating from the radially arranged laterals around the axial stem, are not known from the Dasycladales. Ramifi - cation of laterals to a higher order and the formation of the “chaotic tube” in Izmirella are not characteristic for Acetabu- lariaceae. Gametangia, occurring in the laterals of e. g. Acetab- ularia, have not been observed in the laterals of Izmirella. c) Also the “chaotic” (Girvanella-like) tube layer between the individual thalli of Izmirella rows does not support its in- terpretation as a Dasycladacean. An alternative classifi cation to the Dasycladales might be the red algae. Actually a placement of Izmirella in the Pey- ssonneliacea could be envisaged. In this view the “stacked superimposed whorls” might be interpreted as lamellar thalli growing on some non-calcifi ed erect fi laments (= “axial stem”); Figure 8: Redrawn from Pl. 3, Fig. 7 (quadrangle) showing the edge of a trumpet-like broadened lateral, from which the tubes of the second layer originate. Figure 9: Section through the last cup of specimen illustrated in Pl. 6, Fig. 8 showing the large “cells” of the laterals, numerous tubes of the lid (appearing as bridge between the edges of the cup), micritic fi lling within the bowl (dotted area) and the small spherical elements (gametangia?) within the micritic fi lling. The white area within the micritic fi lling is sparry calcite cement. Geologia Croatica Geologia Croatica 61/2–3 294 this peculiar mode of life may be refl ected by the wavy “bowl- shaped” aspect. Nevertheless, this hypothesis looks inadequ- ate if one considers the absence of a well-defi ned cellular net- work with a hypothallus and perithallus (DENIZOT, 1968) which typifi es the Peyssonneliacea. The cell-like structure (oval or rectangular) of the laterals in sections directly around the axial stem (Pl. 4, Figs. 3, 6; Pl. 5, Figs. 1–4; Pl. 7, Figs. 2, 5, 8), also are similar to some red algae (e. g. Lithoporella, see WRAY, 1977, fi g. 56), but they are tube-like in Izmirella. Different cell sizes, developed as two tube layers of Izmirella, is known from other red algae, e. g. in the crustose coralline red algae Phymatolithon calcareum and Lithothamnium coralloides (ADEY & MC KIBBIN, 1970). The cells are signifi cantly elongated during winter growth. Also the mineralogy of the cells (i. e. content of Mg) in mod- ern calcareous red algae varies from summer to winter (MIL- LIMAN et al., 1971; KOLESAR, 1978). Seasonal cell sizes and variation in Mg-content in calcite of the cell walls is also known from fossil solenoporacean algae (WRIGHT, 1985; WENDT, 1993). The different cell sizes, and possibly differ- ent content of Mg in the cell wall of laterals and “tubes of the second layer” in Izmirella could also refl ect seasonal variation, but these features do not justify classifying Izmirella as a so- lenoporacean red algae. The fan-like branching pattern of the fi rst order of tubes and of the “chaotic” tube layer of Izmirella could support its attribution to the cyanophyceans. Such branching patterns of cells is common in cyanophyceans, but the axial stem of Iz- mirella and the arrangement of laterals around the axial stem are features contrary to the affi liation of Izmirella with this group. Izmirella nov. gen. is surely an alga but its taxonomic po- sition within the algae remain uncertain. ACKNOWLEDGEMENT The investigations were carried out within the research project “Se 416/13” of the fi rst author supported by the Deutsche Forschungsge- meinschaft (DFG). We thank E. Isikli (Izmir) for her kind help during fi eld work and sample preparation. For critical reading of the fi rst draft of the manuscript and for helpful comments, we thank E. Akay (Izmir), I.I. Bucur (Cluj-Napoca). P. Genot (Nantes) and P. De Castro (Naples). We thank also B. Granier (Brest) and an anonymous reviewer, whose helpful comments improved the manuscript. We are grateful to A. Fag- erstrom (Boulder, USA) for his linguistic help and useful comments. REFERENCES ADEY, W. & MCKIBBIN, D.L. (1970): Studies of the maerl species Phy- ma tolithon calcareum (Pallas) nov. comb. and Lithothamnium coral- lio ides Croun, in the Ria de Vigo. – Botanica marina, 13, 100–106. AKDENIZ, N., KONAK, N., ÖZTÜRK, Z. & CAKIR, M.H. 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