Syvertsenia iberica Witkowski & Gomes, 2013

Gomes, Ana, Witkowski, Andrzej, Dąbek, Przemysław, Boski, Tomasz, Moura, Delminda, Szkornik, Katie & Kurzydłowski, Krzysztof, 2013, Syvertsenia iberica (Cymatosiraceae): a new estuarine diatom genus characterized by the position of its process, Phytotaxa 142 (1), pp. 25-36 : 30

Syvertsenia iberica Witkowski & Gomes sp. nov. ( Figs 2–19 )

Valves linear with protracted to capitate apices, 21.4–28.6 (25.2 ± 2.9) µm long, 3.1–4.5 (3.7 ± 0.6) µm wide. Valves slightly arched about transapical axis. The mantle is shallow, except next to the process where a convex expansion of the valve mantle with an areolae situated above the process is observed. The whole valve surface is covered with areolae, except a small part of the valve in the middle which is close to the tubular process. The number of areolae in 10 µm varies between 17 and 20. Close to the process, there is a small oval area devoid of areolae ( Figs 4, 6–8 and 11 ). The single tubular process is positioned on the extension of the valve mantle ( Figs 3, 4 , Figs. 6–8 and Fig. 10 ). The valve linkage consists of one row of marginal, short, Y-shaped linking spines at each side of the valve ( Fig. 14 ). The row of linking spines terminates close to the ocelluli ( Figs. 17 and 19 ). There are two ocelluli (with ca. 20 porelli each and small spines inside— Figs 16–19 ) set on the apices. The ocelluli are slightly displaced from the valve centre ( Figs 10, 16–19 ).

Type: ⎯ SPAIN. Ayamonte : Guadiana Estuary , sandy flat near the river mouth ( Fig. 1B ), station GS1 (37º11’41’’N, 7º24’22’’W, Fig 1C ). Sample collected from surface sediment by Ana Isabel Gomes on the 26 th of May, 2010. Holotype SZCZ slide 18916, illustrated in Figures 6 and 7 ; isotype slide no. 13298/ ALGU in the ALGU Plant and Algae Collection ( Fig. 2 ).

Etymology: ⎯The specific epithet was chosen considering that Guadiana Estuary makes the border between the two countries that constitute the Iberian Peninsula.

Distribution and ecology: ⎯Thus far, known only from the type habitat area i.e. Guadiana Estuary, stations GS1, GS2 and GS18 ( Fig. 1C ). In the referred stations, the salinity of the sediment interstitial water ranges between 19.93 (GS1) and 30.74 g /Kg (GS18) while pH values varies from 7.27 (GS18) to 7.58 (GS2). The substrate grain-size preference varies between medium silt (GS18) and fine sand (GS2). In terms of organic carbon percentage it ranges from 0.36 % (GS2) to 3.40 (GS18). Table 3 presents in detail the physicochemical parameters measured at each sampling station. The river water column adjacent to the sampling stations presents a mean salinity of 26.43 ± 11.13 g /Kg, a pH of 8.20 ± 0.27, dissolved oxygen of 98 ± 19.48 % and a mean temperature of 17.88 ± 5.13º C.

Figures

FIGURE 1. Study area: (A) Location in Iberia Peninsula, (B) Location in the lower area of the Guadiana Estuary and (C) Schematic representation of the sampling transect (elevation relative to the mean sea-level). Illustrations of Sarcocornia perennis (Miller) A. J. Scott (1977: 367) & Halimione portulacoides (L.) Aellen (1938: 126) by Tracey (2010) and Spartina maritima (Curtis) Fernald (1916: 180) by Saxby (2010).

FIGURES 2–9. Syvertsenia iberica. LM images. Figs 3–9: Specimens from the holotype slide. Figs 6, 7: Holotype specimen photographed in various techniques, note the presence of the tubular process on a mantle (arrow) Figs 8, 9: Same specimen photographed in various techniques. Figs 4–6 and 8: Phase contrast. Figs 7 and 9: Differential Interference Contrast. All scale bars = 10 µm.

FIGURES 10–19. Syvertsenia iberica. SEM images from the holotype sample (GS1) from Guadiana Estuary, Spain. Fig. 10: General view of the interior of the process valve. Note the tubular process (white arrow) and the presence of two linearly opposed ocelluli. Fig. 11: Close up to the valve internal view. Fig. 12: Close up of the middle part of the valve. Note the areolae occlusions, tubular process (black arrowhead) and mantle expansion with an areolae (white arrow). Fig. 13: Close up of the tubular process and areolae in the mantle expansion. Fig 14: Close up to the marginal spines. Fig. 15: Close up to the valve face areolae, which present an approximated linear and equidistant distribution. Figs 16, 17: Close up to the ocellulus, external (black arrowhead, Fig. 16) and internal (white arrow, Fig. 16) showing the presence of porelli (note the presence of spines in an external view). Figs 18, 19: Close up to the opposite apex ocellulus external view, note the presence of spines within ocellulus (black arrowhead, Fig. 18). Fig. 10: Scale bar = 10 µm. Fig. 11: Scale bar = 5 µm. Figs 12, 15 and 19: Scale bar = 500 nm. Fig. 13: Scale bar = 250 nm. Fig. 14: Scale bar = 200 nm. Fig. 16: Scale bar = 2 µm. Figs 17, 18: Scale bar = 1 µm.