Aulacoseira veraluciae Tremarin, Torgan & T. Ludwig, 2014

Tremarin, Priscila Izabel, Ludwig, Thelma Alvim Veiga & Torgan, Lezilda Carvalho, 2014, Aulacoseira veraluciae sp. nov. (Coscinodiscophyceae, Aulacoseiraceae): a common freshwater diatom from Brazil, Phytotaxa 184 (4), pp. 208-222 : 215-218

Aulacoseira veraluciae Tremarin, Torgan & T. Ludwig , sp. nov. ( Figs 2‒35 )

Holotype:— UPCB 76037 , Diatom Collection of the Herbarium of Universidade Federal do Paraná, Brazil, illustrated here in Fig. 21 .

Isotype:— BM 101711 ( The Natural History Museum , England) .

Type locality:— BRAZIL. State of Rio Grande do Sul, Tapes and Mostardas municipalities, Patos lake , 30º23’S / 50º41’W to 32º07’S / 52º12’W, phytoplankton, collected from 07 January 1988 by L.C. Torgan .

Etymology:—The new species is named in honor of Dr. Vera Lúcia de Moraes Huszar of National Museum, Rio de Janeiro Federal University, for her dedication to phytoplankton research.

Description: — Cells solitary or joined by short spines to form short or long chains, straight or slightly curved. Valve diameter 3–15 µm, mantle height 4–12 µm. Mantle height/diameter ratio 0.35–2.01. Separation valves with face flat, totally or partially covered by areolae and mantle with deep longitudinal depressions formed by the spine insertion of the adjacent cell. Separation spines attenuate and long (ca. 3‒8 µm in length), one to five per valve, intercalate by other smaller and conical spines, one spine for every two interstriae. Linking valves with a flat face, perforated by marginal areolae that extend into the mantle through the marginal spines. Linking spines short, broadly spathulate with smooth edge, one spine for every two interstriae. Valve mantle usually ornamented by small knobs. Collum narrow, height 0.8‒1.1 µm. Pervalvar rows of areolae straight, 10‒16 in 10 µm. Areolae triangular close to marginal spines become rounded in the middle region of the mantle and elongate near the collum, 10‒15 in 10 µm, occluded by cribra. Ringleiste deep and thick, width1.6‒2.3 µm, protruding into the cell with reinforced rim. One to three rimoportulae above the inner side of the ringleiste. Other rimoportulae near the valve face/mantle junction in the separation and linking valves. External opening of rimoportulae associated with an areola, and not visible in LM. Internal opening of rimoportulae elongate and without stalk. Girdle bands with prominent ligula and finely perforated by round porous, ca. 10‒13 in 1 µm. Valvocopulae fimbriate. Auxospore with 12‒15 µm diameter.

Figures

FIGURES 2–22. Aulacoseira veraluciae, LM. Scale: 10 µm. Figs 2, 3. Initial cells. Figs 4, 5. Valve view of the separation cells. Figs 6, 7. Valve view of the linking cells. Fig. 8. View of the cell lumen showing the ringleiste. Figs 9‒22. Aspect of the chains.

FIGURES 23–29. Aulacoseira veraluciae, SEM, external view. Scales: 5 µm (Figs 23, 29), 2 µm (Figs 24‒28). Fig. 23. Overview of the valve showing the separation spines. Fig. 24. Valve face of the separation cell. Fig. 25. Valve face of the linking cell. Figs 26, 27. Detail of the linking spines. Fig. 28. Detail of the mantle areolae occluded by velum. Fig. 29. Mantle of the linking valves and location of external rimoportulae openings (arrows).

FIGURES 30–35. Aulacoseira veraluciae, SEM. Scales: 2 µm (Figs 30, 31, 34), 1 µm (Figs 32, 33, 35). Figs 30, 31. External rimoportulae openings (arrows) in the separation and linking valves, respectively. Fig. 32. Internal rimoportula opening (arrow) near the valve face/ mantle junction in the separation valve. Fig. 33. Internal rimoportulae openings (arrows) on the ringleist. Fig. 34. Detail of ringleiste. Fig. 35. Aspect of the girdle bands. Note the fimbriate valvocopula (arrow).