Cyclotella petenensis Sylvestre, Paillès & Escobar, 2018

Paillès, Christine, Sylvestre, Florence, Escobar, Jaime, Tonetto, Alain, Rustig, Sybille & Mazur, Jean-Charles, 2018, Cyclotella petenensis and Cyclotella cassandrae, two new fossil diatoms from Pleistocene sediments of Lake Petén-Itzá, Guatemala, Central America, Phytotaxa 351 (4), pp. 247-263 : 248

Cyclotella petenensis Sylvestre, Paillès & Escobar sp. nov. ( Figs. 1–9 )

Type: Lake Petén-Itzá, Department of Petén, Guatemala, Latitude 16° 15’ 50 N, Longitude 89° 15’ 00 W. Lacustrine sediment in Core PI- 6, sample GLAD 9- PET 06-6A-13H2-98,3-99,3 cm (39.35 m below lake floor). Core collected in February 2006.

Holotype: slide PC0612192 and sediment PC0612194 deposited at the Laboratoire de Cryptogamie , Museum National Histoire Naturelle ( MNHN) Paris, France.

Isotype: slides Zu/1094 and sediment R 1278 deposited at the Friedrich Hustedt Diatom Study centre in Bremenhaven, Germany.

Description

Cells circular, drum-shaped, with a diameter between 15 and 60 μm. Central area tangentially undulate, representing one third to half of the valve surface. Central area occupied on the elevated part by two (for smaller specimens) to>20 valve face fultoportae in a semicircular arrangement, the depressed part appears unstructured or colliculate. The total number of central fultoportulae is strongly positively related with cell diameter. Marginal area circumferentially undulate with coarse striae of equal length, 5 to 9 within 10 μm. Marginal striation crossed circumferentially by a «ring» about two third of the valve surface, representing the transition between internal openings of alveoli and central lamina. Stria composed of a main row of large pori starting near the central part and continuing with a double row of smaller ones arranged in a quicunx (staggered). Central fultoportulae formed by a short tubulus surrounded by three satellite pores. Marginal fultoportulae (one tube + three satellite pores) on each costa. Rimoportula on a costa within the ring of mantle fultoportulae.

Figures

FIGURES 1‒9. Type material of fossil lacustrine diatom Cyclotella petenensis from lake Peten Itza, LM.(1‒2) Valve view at two different focus showing striae and marginal alveoli representing the ‘shadow line’ and the tangentially undulated central area with CFP in an arc. (3–9) Size variation of C. petenensis with variable number of CFP related to valve diameter. (4) taken from holotype permanent slide PC0612192. Scale bar = 10μm.Abbreviations. central fultoportulae (CFP).