Campyloneis frenguellii Riaux-Gobin et Guerrero

Al-Handal, Adil Y., Torstensson, Anders & Wulff, Angela, 2022, Revisiting Potter Cove, King George Island, Antarctica, 12 years later: new observations of marine benthic diatoms, Botanica Marina (Warsaw, Poland) 65 (2), pp. 81-103 : 90

Campyloneis frenguellii Riaux-Gobin et Guerrero ( Figures 56–59 , 113, 114 )

Literature: ( Riaux-Gobin and Romero 2003, p. 38, pl. 57, figs. 3–4 as Cocconeis cf. orbicularis ; Riaux-Gobin et al. 2019, p. 161, figs. 54–59).

Description: Length 28–41 µm, width 18–32 µm, striae 3.5– 4 in 10 µm (raphe valve), 2.5– 3 in 10 µm (rapheless valve).

Remarks: This species is characterized by its large marginal alveole which encompass tetraseriate striae. On the rapheless valve, another set of alveole is observed between the marginal alveole and the axial area but these do not reach valve center and their number varies from 2 to 5, their size decreases towards the center. The observed specimens were larger than those reported in the literature cited (17– 18 µm long, 11–13 µm wide).

Ecology and distribution: A marine cold-water species. It is very rarely mentioned in the literature and have only been reported from its type locality in Antarctica and from southern Argentina (Romero 1995). Frequent in the present samples from Potter Cove but were not encountered in the collections made during 2003–2006 from the same locality (Al-Handal and Wulff 2008a,b).

Cocconeis antiqua Tempère et Brun ( Figures 60, 61 ) Literature: (Al-Handal and Wulff 2008b, p. 426, figs. 28–29, 35–36 [as Cocconeis schuettii van Heurck 1909 ]; Scott and Thomas 2005, p. 127, fig. 2.69a–d).

Description: Length 47–72 µm, width 35–47 µm, striae 14– 16 on raphe valve, 24–26 on rapheless valve.

Remarks: The taxonomic position of Cocconeis antiqua has been discussed and revised by Romero (2011) where several taxa previously described by Van Heurck were considered as synonyms of this species. These include C. gautierii var. gautierii , C. gautierii var. inornata , C. litigiosa , C. schuettii var. schuettii , and C. schuettii var. minor Van Heurck.

Ecology and distribution: Cocconeis antiqua does not seem to have been found outside Antarctica since its description in 1909 by Van Heurck (Van Heurck 1909). Frequent in all samples examined from Potter Cove.

Figures

Figures 39–59: Marine benthic diatoms in Potter Cove, King George Island, Antarctica, summer 2015. (39) Lyrella hennedyi. (40) Petroneis sp. (41) Petroneis plagiostoma. (42) Staurophora sp. (43–46) Achnanthes cf. groenlandica, (43, 44) raphe valve, (45) sternum valve, (46) two cells in girdle view. (47) Cocconeis californica. (48) Cocconeis californica var. kerguelensis. (49) Cocconeis costata var. hexagona. (50) Cocconeis dallmannii. (51) Cocconeis fasciolata. (52) Cocconeis imperatrix. (53) Cocconeis matsii. (54, 55) Cocconeis melchioroides. (56–59) Cocconeis orbicularis, (56, 59) sternum valve, (57, 58) raphe valve.

Figures 113–118: SEM images of the marine benthic diatoms in Potter Cove, King George Island, Antarctica, summer 2015. (113, 114) Cocconeis orbicularis, external and internal faces of sternum valve. (115, 116) Fragilariopsis cylindrus, internal valve sides. (117) Entomoneis paludosa. (118) Nitzschia australis.

Figures 60–78: Marine benthic diatoms in Potter Cove, King George Island, Antarctica, summer 2015. (60, 61) Cocconeis antigua. (62) Diploneis smithii. (63) Diploneis weissflogii. (64) Diploneis sp. (65) Caloneis sp. (66, 67) Navicula cancellate. (68) Navicula directa. (69, 70) Navicula perminuta. (71) Navicula sp. (72, 73) Pseudogomphonema kamtchaticum. (74) Trachyneis aspera. (75, 76) Biremis ambigua. (77) Parlibellus crucicula. (78) Pinnularia quadratarea.