Biodiversity of oligotrich ciliates in the South China Sea: description of three new <i>Strombidium</i> species (Protozoa, Ciliophora, Oligotrichia) with phylogenetic analyses

<div><p>The morphology and small subunit ribosomal RNA (SSU rRNA) gene sequences of three new species of ciliates in the genus <i>Strombidium</i> are recorded: <i>S. paracapitatum</i> sp. nov., <i>S. cuneiforme</i> sp. nov., and <i>S. caudispina</i> sp. nov. <i>Strombidium paracapitatum</i> sp. nov. is characterized by having a prominent and transparent apical protrusion and two types of extrusomes. <i>Strombidium cuneiforme</i> sp. nov. differs from its congeners in the combination of its long conical body shape, eyespot and elongated tail. <i>Strombidium caudispina</i> sp. nov. is recognized by its posterior spine and short ventral kinety. In SSU rRNA gene trees, all members of the genus <i>Strombidium</i> cluster into three separate groups. The first group is composed of nine <i>Strombidium</i> species including <i>S. cuneiforme</i> sp. nov., plus <i>Williophrya maedai</i>. The second group consists of <i>S. paracapitatum</i> sp. nov., <i>S. caudispina</i> sp. nov. and three congeners. The third group comprises <i>S. conicum</i> and <i>S. chlorophilum</i>.</p><p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:25871A6B-772A-4D26-9940-ACE2B5F1EA07" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:25871A6B-772A-4D26-9940-ACE2B5F1EA07</a></p></div>