Taxonomy and identification of the armored dinoflagellate genus Heterocapsa (Peridiniales, Dinophyceae)

Abstract

Abstract:The armored dinoflagellate genus Heterocapsa is composed of relatively small species, including a species responsible for harmful red tides, H. circularisquama. Some Heterocapsa species such as H. rotundata and H. triquetra have been well documented as red tide-forming species, but are not recognized as causing harmful effects. Following sequential shellfish mass mortalities in the coastal waters of western Japan due to H. circularisquama red tides, this species has attracted considerable interest. Many properties of this species, such as its distribution and growth characteristics, have been investigated to better understand the mechanisms involved in harmful red tide formation. Related to the need for unambiguous identification of H. circularisquama, several unidentified (or undescribed) Heterocapsa species, which must be distinguished from the harmful taxon, have been detected sympatrically in regions where H. circularisquama blooms occur. However, the taxonomic affiliation of these Heterocapsa species have not yet been determined because several characteristics of Heterocapsa (e.g. body scale ultrastructure) have not yet been reported from all described species due to the changing taxonomic criteria. After the taxonomic ambiguities in this genus were resolved, cellular and body scale morphology of Heterocapsa were reinvestigated and several new species were described. In the present paper, the taxonomic history and morphological characters of the genus Heterocapsa are summarized.

The phylogeny of Heterocapsa sp. (Dinophyceae) isolated from the south coast of Iran during a Cochlodinium polykrikoides bloom

“…Species of the genus Heterocapsa are small in size and have almost the same morphological characters, such as thecal plate pattern and reticulated peripheral chloroplast, which makes their identification by light microscopy difficult (Iwataki, 2008). Although tabulation does not vary much among the species of Heterocapsa (Uysal et al, 2003), thecal plate arrangement was noted as an important feature in the identification of most dinoflagellates (Fensome et al, 1993).…”

“…Although tabulation does not vary much among the species of Heterocapsa (Uysal et al, 2003), thecal plate arrangement was noted as an important feature in the identification of most dinoflagellates (Fensome et al, 1993). In addition, many researchers noted that the fine structure of body scales, also present in the genus Heterocapsa, is a more reliable feature for species identification than other morphological characters (Iwataki et al, 2002;Tamura et al, 2005;Iwataki, 2008). Cell shape, cell size, and position of the nucleus and pyrenoid vary among some Heterocapsa species and are also useful for species identification (Iwataki, 2008); however, molecular data are necessary to address the systematic level of the species (Daugbjerg et al, 2000).…”

Isolation and Physiological Characterization of a New Algicidal Virus Infecting the Harmful Dinoflagellate Heterocapsa pygmaea

“…established a new genus, Heterocapsa (Iwataki et al, 2008;Pennick and Clarke, 1977;Tamura et al, 2005). Therefore, the host alga was identified by the sequence analysis of the large-subunit RNA gene (D1-D2 region) and the 18S rDNA region and transmission electron microscopic observation.…”

“…The genus Heterocapsa comprises small, marine, gymnodinioid dinoflagellates (Loeblich et al, 1981). Heterocapsa pygmaea has been isolated from Hong Kong to Japan (Iwataki, 2008), but this species is newly identified from Korean coastal waters. In the present study, the isolation, growth in culture, life-cycle, stability, and gene content of HpygDNAV, a novel DNA virus, are described.…”

“…AF201747) which had been reclassified as Heterocapsa spp. (Iwataki et al 2008). The host was further identified as H. pygmaea based on the morphological observation showing the typical characteristics of the species including the cell size, body scale size, and the number of pyrenoid among them.…”