Thalassiosira catharinensis M. Garcia, 2016

Garcia, Marinês & Dutra, Débora Bärwaldt, 2016, A new species of nanoplanktonic diatom: Thalassiosira catharinensis (Bacillariophyceae) from Southern of Brazil, Phytotaxa 288 (1), pp. 61-68 : 62

Thalassiosira catharinensis M. Garcia , sp. nov. ( Figs 1–14 )

Valve faces are circular and plane, 4.4–6.6 μm diameter ( Figs 1–6 ). The mantle is shallow, 1–2 areolae in height. Areolae are round to elliptical, with external foramina, 39–48 in 10 μm, arranged in radial striae ( Figs 5, 7–8 ). Cribra are internal and finely perforated ( Fig. 13 ). There is an external ring of fultoportulae, 3.0– 3.3 in 10 μm, with short external tubes, ca. 300 nm long ( Figs 5–9 ). Rimoportulae is next to a marginal fultoportula, with an external tube of about the same diameter as that of the fultoportulae ( Figs 5–10 ) or rarely wider. One fultoportula is present at the valve face center, with short external tubes ( Figs 6, 7 ). Internally, central and marginal fultoportulae present three satellite pores ( Figs 11–14 ) and the rimoportula is small and shallow ( Figs 5 and 11–14 ). The external tubes of the rimoportula and the fultoportulae open in distinct directions ( Figs 6, 10 ). There is a valvocopula with a ring of round poroids, ca. 70 in 10 μm at the advalvar edge ( Figs 5, 8 ).

Type:— BRAZIL. Santa Catarina State: Laguna, Praia do Gi, 29° 28’ 01.01” S, 48° 45’ 58.76” W, M. Garcia, March 10, 2014 (holotype ICN!, slide M. Garcia 160320, Department of Botany, here illustrated as Fig. 5 ).

Paratype: Sample PEL 24220 in the Herbarium PEL of Universidade Federal de Pelotas (Pelotas) collected from intertidal sediment surface (sand) in Santa Catarina: Bombinhas, Zimbros (27 o 10’52.09”S, 48 o 31’17.62”W). Sampled on March 14, 2014.

Etymology:— Thalassiosira catharinensis is named after the type locality: Santa Catarina State in Brazil.

Figures

FIGURES 1–4. Thalassiosira catharinensisin LM images. Figs 1–2. Valves views. Figs 3–4. Group of frustules. Scale bars: 5μm

FIGURES 5–10. Thalassiosira catharinensis. SEM, external views. Rimoportula and fultoportulae are indicated with white arrows. 5. Frustule in external view showing part of the internal view at right hand side. Note the valvocopula with a row of pores at the advalvar edge (*) and areolae with external foramina. The small and shallow internal rimoportula opening is indicated by a black arrow. 6. External view of a frustule showing short external fultoportulae tubes (black arrows). Note the fultoportulae and rimoportula tubes openings in different directions (white arrow). 7. Another valve showing fultoportulae and rimoportula external tubes located next to each other and at the same level. 8. Valve showing fultoportulae and rimoportula tubes openings in distinct directions and a valvocopula with a row of pores at the advalvar edge (*). 9. Valve partially covered by mucilage showing fultoportulae and rimoportula external tubes located next to each other and at the same level. 10. Part of a valve showing fultoportulae and rimoportula tubes openings in different directions. Scale bars: 1 μm.

FIGURES 11–14. Thalassiosira catharinensis. SEM, internal views. Rimoportula indicated with a white arrow. 11. Internal view showing fultoportulae with three satellite pores. 12. Internal general view showing a rimoportula located next to a fultoportula with three satellite pores. 13. Detail of the central fultoportula with three satellite pores. 14. Part of a valve showing in detail central and marginal fultoportulae with three satellite pores. A small and shallow rimopotula is located at the same level than the marginal fultoportula. Scale bars: Figs 11–12, 14 = 1 μm, Fig. 13 = 500nm. FIGURE 15. Thalassiosira minima. SEM, internal view showing two central fultopotulae with three satellite pores and marginal fultoportulae with four satellite pores. Note the internal rimportula opening (white arrow) not aligned with the marginal fultoportulae ring. Scale bar: 1 μm