The marine diatom family Rhizosoleniaceae: Morphology and distribution in Korean coastal waters

Abstract

In order to understand morphology and distribution of diatoms in the family Rhizosoleniaceae in coastal waters of Korea, samples were taken 341 sites from September 2008 to February 2010 and specimens were identified by using LM and SEM. In total 32 sites, 6 genera 18 species were identified. 6 genera in the family Rhizosoleniaceae were divided two groups by valve shape and areolae. The first group were composed of a conoidal valve and loculate areolae. They were identified four genera (Rhizosoelnia, Proboscia, Pseudosolenia, Neocalyptrella). The second group were composed of a flat or rounded valve and poroid areolae. They were identified two genera (Guinardia, Dactyliosolen). The genus Rhizosoelnia were observed nine species (R. bergonii, R. fallax, R. formosa, R. hyalina, R. imbricata, R. setigera, R. pungens, R. cf. imbricata and R. cf. fallax). They were identified by girdle segment structure in column, external process shape, otaria, clasper, continuos area, striation and velum structure. The genus Proboscia were observed two species (Proboscia alata and P. indica). They were identified by proboscis structure, clasper of position and symmetry. The genus Guinardia were founded three species (Guinardia delicatula, G. flaccida and G. striata). They were identified by process of shape and position. The genus Dactyliosolen were founded two species (Dactyliosolen fragilissimus and D. phuketensis) and were identified by external tube of position in valve marginal part. Neocalyptrella robusta were identified by ‘calyptra' structure. Psuedosolenia calcar-avis were identified by claw-like process and lacking otaria. To identify the family Rhizosoleniaceae, the most important characters are valve shape and areolae. This study confirmed also important characters which were external process or tube of position and shape in valve marginal part. Of these, R. fallax, R. formosa and D. phuketensis were found firstly in the Korean coastal waters.