Diplopora obliquspora, Senowbari-Daryan, 2014

Senowbari-Daryan, Baba, 2014, Dasycladales Algae From The Norian-Rhaetian Reef Carbonates Of Argolis Peninsula, Greece, Acta Palaeontologica Romaniae 10 (1 - 2), pp. 1-2 : 42-45

Diplopora obliquspora nov. sp.

( Fig. 3 ; Fig. 5 a-d)

? 1979 Clypeina sp. - Flügel, pl. 2, fig. 9.

? 1980 Clypeina sp. - Senowbari-Daryan, p. 67, pl. 14, fig. 5-6.

Derivatio nominis: Obliquus (latin) = oblique, porus (latin) = pore. Named for the oblique running laterals.

Holotype: Specimen illustrated in Fig. 5c (magnification in Fig. 3 , thin section G75 ).

Locus typicus: Norian-Rhaetian reef carbonates near the town Sarmeika ( Fig. 1 ).

Stratum typicum: Norian-Rhaetian reef carbonates.

Diagnosis: Cylindrical thallus with a relatively wide axial cavity. Tufts of trichophorous laterals are originated from the common base. Oblique orientation of the laterals. A thin wall at the base of the thallus wall surrounds the axial cavity. Metaspondyl arrangement of the laterals.

Material: Four specimens.

Description: The thallus of this cylindrical and tiny alga is composed of a relatively thick thallus wall. The length of the holotype ( Fig. 3 ) is about 8 mm with thallus diameter (D) of 1.4 mm. Diameter of axial cavity (d) is 0.6 mm (about 43%). Characteristic of the alga is the metaspondyl arrangement of the laterals as indicated by the relict appearance of the tufts through the thallus wall ( Fig. 3 : large arrows). Each tuft is composed of about five laterals (in longitudinal section three are recognizable, Fig. 3 : small arrows).

Laterals are oriented oblique to the axial cavity with about 30-75° off-axis angle).

Around the axial cavity a thin wall of only 0.06 mm thickness is pierced by the base of laterals. Diameter of individual laterals is about 0.05 mm. Individual laterals are extended spine-like over the thallus surface appearing as circles in cross section (see at the base of the thallus). Discussion: The attribution of this species to the genus Diplopora is based on the metaspondyle arrangement of the laterals and the tufts arising from the common base. Cysts within the axial cavity were not found in the Sarmeika species. Such spine-like extended individual laterals of the new species – like in Probolocupsis sarmeikensis described above – are not known from the other species of the genus Diplopora .

Diplopora obliquspora – similar sections were described from the Norian-Rhaetian reef carbonates of the Northern Calcareous Alps as Clypeina sp. by Flügel (1979) and Senowbari-Daryan (1980). Both specimens from the Alps, including their dimensions of the thallus are similar to the Sarmeika species illustrated in Fig. 5a . The classification of these specimens as Diplopora obliqusipora is uncertain.

Diplopra obliquspora differs from the known species of the genus by the inclination of the laterals, very thin laterals and the outer surface of the thallus. Dimensions are given in table 3.

Figures

Fig. 3 Diplopora obliqusipora nov. sp. (Holotype). The magnification from Fig. 5c shows the relics of metaspondyle arrangement of the tufts (large arrows, also the cross sections of the laterals at the base of the thallus indicate the metaspondyle arrangement of the laterals). Small arrows indicate the tufts arising from the common base. The thin wall around the axial cavity is clearly recognizable.

Fig. 5 Diplopora obliguspora nov. sp. (a to d) and Probolocuspis tenuiparia nov. sp. (e to l) from the Norian-Rhaetian reef carbonates of Sarmeika, Peloponnes, Greece. a Specimen exhibits the thin wall around the axial cavity and the spine-like extended laterals. Thin section G1, x32. b Similar section as Fig. a showing the common base of oblique orientation of individual laterals. Thin section G89, x12. c (Holotype). Longitudinal section exhibiting the metaspondyle arrangement of the laterals, tuft of laterals and the thin wall around the axial cavity (for more information see Fig. 3). Thin section G75, x8. d Two cross sections exhibiting the spine-like extended individual laterals. G12, x20. e Cross sections through several specimens with thin thallus wall. Thin section G012, x20. f Sections through three specimens with relatively thick thallus wall but the individual laterals are recognizable. Thin section G08a, x25. g Oblique to longitudinal section. Thin section G08a, x20. h Holotype. The oblique section shows the individual laterals at the base. Thin section G08a, x20. i Sections through four specimens showing the laterals in part. Thin section G08a, x20. j Sections similar to Fig. i. Thin section G08a, x20. k Cross sections clearly showing the spine-like extended laterals. Thin section G08a, x40. l Similar to k. Thin section G40/1, x12.

Fig. 1 Geographic position of the Norian-Rhaetian reef locality north of the town of Sarmeika, Peloponnes, Greece.