The planktonic diatom genus Chaetoceros Ehrenberg (Bacillariophyta) from the Adriatic Sea Author Bosak, Sunčica University of Zagreb, Faculty of Science, Department of Biology, Rooseveltov trg 6, HR- 10000 Zagreb, Croatia Author Sarno, Diana Stazione Zoologica Anton Dohrn, Department of Integrative Marine Ecology, Villa Comunale, 80121 Naples, Italy text Phytotaxa 2017 2017-07-21 314 1 1 44 http://dx.doi.org/10.11646/phytotaxa.314.1.1 journal article 10.11646/phytotaxa.314.1.1 1179-3163 13700770 Chaetoceros peruvianus Brightwell (1856: 107) ( Figs 24–26 ) References :— Hustedt (1930) , Cupp (1943) , Rines & Hargraves (1988) , Hernández-Becerril (1996) , Shevchenko et al. (2006) , Sunesen et al. (2008) , Kooistra et al. (2010) . Synonyms: — Chaetoceros convexicornis Mangin , Chaetoceros peruvianus var. currens Peragallo , Chaetoceros peruvioatlanticus Karsten , Chaetoceros chilensis Krasske. Morphometry: —a.a.: 15–39 μm; p.a.: 16–33 μm LM: —Cells are solitary, containing numerous small plastids located in the cell body and in the setae ( Figs 24–26 ). The frustules are heterovalvate with a convex anterior valve and a concave posterior valve. The mantle of both valves is usually high, with a distinct constriction near the mantle edge, and the girdle is small. All setae lie in the apical plane and are oriented towards the same (posterior) end of the cell ( Fig. 24 ). The setae of the anterior valve emerge very close to the valve centre and are drawn up in the pervalvar direction touching each other with a groove between them, and fuse in the valve centre ( Fig. 25 ). The setae then sharply bend back in a curve toward the posterior end of the cell. The posterior setae originate close to the valve margins and then curve from the cell in the same direction as the anterior ones becoming almost parallel to the pervalvar axis. Setae are thick, coarse, long and ornamented with spines visible in LM ( Fig. 26 ). Distinctive features: —Solitary, heterovalvar cells, all setae curved towards the posterior cell end. Basal parts of anterior setae touching each other with a groove between them.