Chaetoceros lauderi Ralfs
Creators: name: Bosak, Sunčica
name: Sarno, Diana
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Chromista
Ochrophyta
Bacillariophyceae
Chaetocerotales
Chaetocerotaceae
Chaetoceros
Chaetoceros lauderi

description: Chaetoceros lauderi Ralfs in Lauder (1864a: 77) (Figs 142–153)   
 References: — Hustedt (1930), Cupp (1943), Hargraves (1979), Rines & Hargraves (1988), Hernández-Becerril & Flores Granados (1998), Jensen & Moestrup (1998), Sunesen et al. (2008), Kooistra et al. (2010), Ishii et al. (2011).   
 Synonyms: — Chaetoceros weissflogii Schütt.   
 Morphometry: —a.a.: 15–39 μm; p.a.: 27–63 μm.   
 LM: —Cells are united into long straight chains which are slightly twisted around the chain axis (Fig. 142). In valve view cells are circular to elliptical, in girdle view rectangular with sharp corners and pervalvar axis generally longer than the apical axis (Fig. 143). There are numerous (25–45) small chloroplasts present in each cell (Fig. 143). The valve face is flat. The mantle is low without constriction at its edge while the girdle is usually very broad. Intercalary setae emerge from the corners of the valves, fuse without a basal part and immediately diverge in different directions. Apertures are very narrow and slit-like (Fig. 143). Setae are generally straight, extending perpendicular to the chain axis, with some of them curving towards either end of the chain (Fig. 142). In valve view setae diverge from the apical plane at an angle of 30–40°; in some cases one seta is parallel with the apical plane and the other is more or less perpendicular. Terminal setae are morphologically similar to intercalary ones, strongly diverging in a broad Ushaped curve (Fig. 142).   
 EM: —The valve face is ornamented with densely and irregularly distributed anastomosing costae radiating from a relatively large central annulus (Figs 144, 145) and becoming parallel on the valve mantle (Fig. 146). The area between costae is hyaline. The marginal ridge is often ornamented with a very low hyaline rim (Fig. 147). Terminal valves possess a slit-shaped rimoportula (Figs 146, 148) with an external wide flattened tube (Fig. 147). Setae are circular in cross-section, ornamented with small poroids and shark fin-shaped spines arranged in a spiral pattern (Fig. 149). The girdle bands have parallel transverse ribs alternating with less silicified areas perforated by irregularly distributed small poroids (Fig. 150). The resting spores are ornamented with long spines on their primary valve and few long thing capilli on the secondary valve. (Fig 151). The capitate primary valve of the resting spore is constricted at its base and spines which are either completely straight or sharply bent near the tip (Fig. 152). Secondary valve is flat to vaulted, either with smooth surface or ornamented with thin and very long hair-like spines (capilli) which are commonly present in a form of a single ring on the mantle advalvar margin (Fig. 153).   
 Distinctive features: —Elongated cells, very narrow and almost non-existent apertures. Chains slightly twisted around the axis and setae diverging in all directions. Resting spores with long spines on the capitate primary valve and ring of long capilli around the secondary valve mantle.
description: Published as part of Bosak, Sunčica & Sarno, Diana, 2017, The planktonic diatom genus Chaetoceros Ehrenberg (Bacillariophyta) from the Adriatic Sea, pp. 1-44 in Phytotaxa 314 (1) on pages 28-30, DOI: 10.11646/phytotaxa.314.1.1, http://zenodo.org/record/13700770