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Cocconeis subantarctica sp. nov. from Kerguelen Archipelago (Austral Ocean) and comparison with Cocconeis stauroneiformis (W.Smith) Okuno

Catherine Riaux-Gobin
Catherine Riaux-Gobin
 und 
Andrzej Witkowski
Andrzej Witkowski
   | 27. Sept. 2017
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Article Category: Original research paper
Online veröffentlicht: 27. Sept. 2017
Seitenbereich: 350 - 362
Eingereicht: 28. Jan. 2017
Akzeptiert: 23. März 2017
DOI: https://doi.org/10.1515/ohs-2017-0036
© 2017 Faculty of Oceanography and Geography, University of Gdańsk, Poland. All rights reserved
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Cocconeis subantarctica. SEM. monospecific clump (possibly in a fecal pellet). Scale bar: 20 μm
Cocconeis subantarctica. SEM. monospecific clump (possibly in a fecal pellet). Scale bar: 20 μm

Figure 2a-i

Cocconei subantarctica. LM (Pointe Bizet, Kerguelen Main Island). Complete frustule (a-b); often subdiscoid (d-e, g); elliptic small specimen with SVVC without fimbriae (c arrowhead); SVs with one virga slightly larger on one side of the valve (d-e arrowheads), SV areolae are not arranged in a regular axial pattern (d-e); small elliptic SV with pearl-like marginal areolae (f); RVs (g-i) with one virga slightly larger on one side (h arrowhead), and RV areolae arranged along axial rows. Note the marginal hyaline rim and large marginal areolae. Scale bar: 10 μm
Cocconei subantarctica. LM (Pointe Bizet, Kerguelen Main Island). Complete frustule (a-b); often subdiscoid (d-e, g); elliptic small specimen with SVVC without fimbriae (c arrowhead); SVs with one virga slightly larger on one side of the valve (d-e arrowheads), SV areolae are not arranged in a regular axial pattern (d-e); small elliptic SV with pearl-like marginal areolae (f); RVs (g-i) with one virga slightly larger on one side (h arrowhead), and RV areolae arranged along axial rows. Note the marginal hyaline rim and large marginal areolae. Scale bar: 10 μm

Figure 3a-g

Cocconeis subantarctica. SEM (Pointe Bizet, Kerguelen Is.). SV in the external view, note the subround shape (an illustration of the holotype); small elliptic SV with oblong complex marginal areolae separated from the rest of the stria by a hyaline rim (b framed arrow), and SVVC possibly open at both apices (b arrowheads); SV convex and flat (c); SV apex with 4 cingular bands (numbered 1-4), from which several are open; note a ligula (d arrowhead); one SV virga larger on one side (e arrowhead); detail of SV ornamentation with a kind of hymenate pierced rotae (f arrowhead), detail of the marginal complex and larger areolae (g). Scale bars: 5 μm (a-b), 3 μm (e), 2 μm (c), 500 nm (f), 400 nm (g)
Cocconeis subantarctica. SEM (Pointe Bizet, Kerguelen Is.). SV in the external view, note the subround shape (an illustration of the holotype); small elliptic SV with oblong complex marginal areolae separated from the rest of the stria by a hyaline rim (b framed arrow), and SVVC possibly open at both apices (b arrowheads); SV convex and flat (c); SV apex with 4 cingular bands (numbered 1-4), from which several are open; note a ligula (d arrowhead); one SV virga larger on one side (e arrowhead); detail of SV ornamentation with a kind of hymenate pierced rotae (f arrowhead), detail of the marginal complex and larger areolae (g). Scale bars: 5 μm (a-b), 3 μm (e), 2 μm (c), 500 nm (f), 400 nm (g)

Figure 4a-d

Cocconeissubantarctica. SEM (Pointe Bizet, Kerguelen Is.). SV in the internal view. Eroded SV in the internal view with flat virgae (a arrow); SVVC with undulating edge (b arrowhead), flat virgae, and SV areolae with a kind of pierced rota (b arrow); broken frustule showing RV marginal large and complex areolae (c arrow), SVVC still in place, with undulating short fimbriae (c arrowhead); detail of marginal complex areolae with domed hymenes still in place (d arrowhead) and low virgae (d arrow). Scale bars: 3 μm (a), 1 μm (b), 500 nm (c-d)
Cocconeissubantarctica. SEM (Pointe Bizet, Kerguelen Is.). SV in the internal view. Eroded SV in the internal view with flat virgae (a arrow); SVVC with undulating edge (b arrowhead), flat virgae, and SV areolae with a kind of pierced rota (b arrow); broken frustule showing RV marginal large and complex areolae (c arrow), SVVC still in place, with undulating short fimbriae (c arrowhead); detail of marginal complex areolae with domed hymenes still in place (d arrowhead) and low virgae (d arrow). Scale bars: 3 μm (a), 1 μm (b), 500 nm (c-d)

Figure 5a-e

Cocconeis subantarctica. SEM (Pointe Bizet, Kerguelen Is.). RV in the external view, note the round shape (a) with oblong complex marginal areolae and the presence of a larger asymmetrical virga (a-b arrowheads); detail of the marginal row of complex areolae with a kind of pegs (d arrowhead); apex void of areolae (c framed arrow), and close proximal raphe endings (c arrowhead); detail of a terminal raphe ending (e arrowhead). Scale bars: 5 μm (a), 3 μm (b), 1.8 μm (c), 1 μm (d), 700 nm (e)
Cocconeis subantarctica. SEM (Pointe Bizet, Kerguelen Is.). RV in the external view, note the round shape (a) with oblong complex marginal areolae and the presence of a larger asymmetrical virga (a-b arrowheads); detail of the marginal row of complex areolae with a kind of pegs (d arrowhead); apex void of areolae (c framed arrow), and close proximal raphe endings (c arrowhead); detail of a terminal raphe ending (e arrowhead). Scale bars: 5 μm (a), 3 μm (b), 1.8 μm (c), 1 μm (d), 700 nm (e)

Figure 6a-d

Cocconeis subantarctica. SEM (Pointe Bizet, Kerguelen Is.). RV in the internal view. Marginal rim and subtle helictoglossa (6 arrowheads) and narrow RVVC with no fimbriae (a twin arrowheads); central area, with proximal raphe endings bent in opposite directions (b arrowheads). Entire valve with the cingulum, note the axial rows of areolae (c); detail of an apex with subtle helictoglossa, complex marginal areolae (d arrowhead) and open copula (d arrows). Scale bars: 3 μm (a, c), 1 μm (b, d)
Cocconeis subantarctica. SEM (Pointe Bizet, Kerguelen Is.). RV in the internal view. Marginal rim and subtle helictoglossa (6 arrowheads) and narrow RVVC with no fimbriae (a twin arrowheads); central area, with proximal raphe endings bent in opposite directions (b arrowheads). Entire valve with the cingulum, note the axial rows of areolae (c); detail of an apex with subtle helictoglossa, complex marginal areolae (d arrowhead) and open copula (d arrows). Scale bars: 3 μm (a, c), 1 μm (b, d)

Figure 7a-g

Cocconeis scutellum var. stauroneiformis W.Smith (1852: Supp. Pl. 30, fig. 34 β) (a). Cocconeis scutellum Ehrenberg in Smith (1852: pl. 3, fg. 34) (b). Cocconeis scutellum var. stauroneiformis W.Smith in Van Heurck (1880: fgs 10-11) (c). Cocconeis scutellum var. stauroneiformis Sm. in Peragallo & Peragallo (1897-1908: pl. 4, fg. 4) (d). Cocconeis paniformis Brun and allied, in Schmidt et al. (1874-1959: pl. 189, fgs 16-20, see text) (e). Cocconeis scutellum var. y in Roper (1858: pl. 3, fg. 9) (f). Cocconeis scutellum Ehrenberg f. parva in Peragallo & Peragallo (1897-1908: pl. 4, fg. 3) (g). Scale bars: 20 μm. Refer to Roper (1858) and Schmidt et al. (1874-1959) for other illustrations.
Cocconeis scutellum var. stauroneiformis W.Smith (1852: Supp. Pl. 30, fig. 34 β) (a). Cocconeis scutellum Ehrenberg in Smith (1852: pl. 3, fg. 34) (b). Cocconeis scutellum var. stauroneiformis W.Smith in Van Heurck (1880: fgs 10-11) (c). Cocconeis scutellum var. stauroneiformis Sm. in Peragallo & Peragallo (1897-1908: pl. 4, fg. 4) (d). Cocconeis paniformis Brun and allied, in Schmidt et al. (1874-1959: pl. 189, fgs 16-20, see text) (e). Cocconeis scutellum var. y in Roper (1858: pl. 3, fg. 9) (f). Cocconeis scutellum Ehrenberg f. parva in Peragallo & Peragallo (1897-1908: pl. 4, fg. 3) (g). Scale bars: 20 μm. Refer to Roper (1858) and Schmidt et al. (1874-1959) for other illustrations.

List of materials examined, including locality, geographical coordinates

Locality Island Date Material Zonation Latitude Longitude
Mayès I. Kerguelen 20.01.1991 sediment 20 m deep 49°28′20″S 69°55′55″E
Pointe Bizet 18.01.1991 intertidal 49°31′12″S 69°54′36″E

Morphometrics and features of 1) C. subantarctica sp. nov. (Kerguelen Is., present study), 2) C. stauroneiformis (cf. Riaux-Gobin & Romero 2003, Kerguelen Is.) and 3) C. stauroneiformis sensu Romero (1996, diverse origin)

Cocconeis subantarctica sp. nov. present study n = 80 Cocconeis stauroneiformis (W.Smith) Okuno sensu Riaux-Gobin & Romero (2003) Cocconeis stauroneiformis (Rabenh.) Okuno sensu Romero (1996) Cocconeis scutellum var. posidoniae M.De Stefano, D.Marino & L.Mazzella (2000)
Valve face subround to elliptic elliptic elliptic to elliptic-lanceolate elliptic
Length (µm) min-max 12-18 15-32 9.6-36 -
14.6 ± 1.0
Width (µm) min-max 8-15 8-21 5.5-27 -
10.3 ± 1.3
SV stria density min-max 11-14 8-9 6-11 12-14
12.6 ± 0.9
uniseriate, rotate and reniform hymenate occlusions wavy transapical rows, externally complex, internally uniseriate externally tetra- to pentaseriate, internally uniseriate uniseriate, transapical rows of areolae with axial bar, rotate or not
RV stria density min-max 12-14 8-10 6-12 18-23
13 ± 0.6
uniseriate, hymenate reniform occlusions biseriate in mid-valve, complex on the margin biseriate, tetra- to pentaseriate at the margin uniseriate
SV sternum straight, relatively large straight, narrow, externally depressed (thickened internally) straight, narrow, concave straight, narrow
SV fascia one virga larger on one side absent absent absent
Marginal SV areolae transapical to quadrangular group of hymenate reniform occlusions undifferentiated from the other areolae - biseriate to triseriate occlusions
SV marginal rim often present absent absent absent
SV internal virgae large, flat thickened elevated narrow, not elevated
SVVC with short undulations, possibly open at both ends short fimbriae reduced fimbriae, open at both ends digit fimbriae
RV fascia often assymetrical more or less wide present absent
RV marginal rim present robust present present
Marginal RV areolae transapical and complex large group of concentric hymenate reniform occlusions apically elongated group of hymenate reniform occlusions group of hymenate reniform occlusions striae biseriate on the mantle
RVVC open, without fimbriae - short fimbriae, open at one apex fused fimbriae
Biogeography Kerguelen Is. Kerguelen Is. diverse origin Ischia I. (Italy)
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