Clypeina lagustensis n.sp., a new calcareous alga from the Lower Tithonian of the Lastovo Island (Croatia)

Abstract

Clypeina lagustensis n. sp. has been found in the Lower Tithonian deposits of Lastovo Island (Dalmatia, Croatia). It is visually similar, obviously related and in some sections appears almost identical, to Clypeina jurassica FAVRE, from which it differs by visible swellings and thinning of the central cavity, more pronounced distance between the neighbouring whorls of fertile laterals, and in the shape and structure of the interverticillate thallus parts, characterized by having well developed, hairy, sterile laterals. These, after emerging from the exit pore, divide into several bundles which form a common tuft with a calcareous envelope in the proximal part.

Aloisalthella, a new genus of fossil Polyphysacean green algae (Chlorophyta, Dasycladales), with notes on the genus Clypeina (Michelin, 1845)

“…Similar features were documented in Clypeina sulcata by Radoičić (1969: text- figures 6.c-d, 9.a-d, 10.a-c) and followers (e.g., Granier, 1986: plate 9, figures d, i;De Castro, 1997: plate 19;plate 20, figures 2-3, 5-6;Schlagintweit et al, 2005: text-figure 35b-d). In our opinion, the recently described C. lagustensis Sokač et al, 2014, with numerous sterile verticils merely represents an ecological variant of C. sulcata (Alth, 1882). Sections documenting these sterile laterals are commonly subaxial (Figures 9.3, 11) or deep tangential, rarely oblique ( Figures 8.4, 9.2b, 10.1) or subtransverse (Figure 12.3, 12.6, 12.9), and the FIGURE 8.…”

Assessing Milankovitch forcing in disconformity‐prone cyclic shallow‐water carbonates, Upper Jurassic (Kimmeridgian), Adriatic Platform, Croatia

“…Ages of Upper Jurassic units of the Adriatic Platform are based on benthic foraminifera and calcareous algae. The Late Jurassic−earliest Cretaceous has several index species and biozones in the benthic foraminifera (Husinec et al ., 2000; Husinec & Sokač, 2006; Velić, 2007), whereas the Upper Jurassic dasycladalean algae form four distinct biozones (Nikler & Sokač, 1968; Velić, 1977; Velić & Sokač, 1978; Sokač et al ., 2014; Prtoljan et al ., 2015). In addition to the biostratigraphic control, δ 13 C chemostratigraphic profiles from the section were compared with other European δ 13 C profiles (Price & Rogov, 2009; Nunn & Price, 2010; Colombié et al ., 2011; Price et al ., 2016) to further constrain the stage boundaries (Fig.…”