Ji Hye Kim

Pleurostomatids are raptorial ciliates that form a very distinct group within the Haptoria. Traditionally, the order Pleurostomatida was divided into two families: the Amphileptidae with two perioral kineties and a suture formed by the right side ciliary rows, and the Litonotidae with three perioral kineties and without suture. However, molecular phylogenies depicted the “traditional” Amphileptidae as a paraphyletic assemblage nesting also the Litonotidae. To overcome this problem we have analyzed genealogy of pleurostomatids using morphological data and 18S rRNA gene sequences, including newly sequenced genera Acineria and Kentrophyllum. Specifically, we have combined a morphological and molecular approach and have used also some other phylogenetic tools such as phylogenetic networks, split spectrum analysis, quartet mapping as well as the likelihood method of tracing history of morphological characters. These analyses show that: (1) there are not two but three distinct pleurostomatid lineages – Epiphyllidae fam. nov., Amphileptidae and Litonotidae; (2) epiphyllids (Epiphyllum + Kentrophyllum) represent a basal pleurostomatid group which is defined by two perioral kineties, by the presence of a suture on both the right and the left side of the body, by the loss of the oral bulge extrusomes, and by the extrusome fringe extending all around the body except for the oral region; (3) the families Amphileptidae and Litonotidae are monophyletic each, and represent sister groups; (4) Acineria belongs to the Litonotidae, as already indicated by morphological data; (5) Loxophyllum is a monophyletic and crown genus of the Litonotidae; and (6) Litonotus is paraphyletic, which could be very likely caused by a rapid radiation event that did not allow primary nucleotide homologies to be fixed.

Brackish water populations of Pinacocoleps pulcher were collected from a lagoon in Korea. This species has never been described using silver impregnation and nuclear small subunit ribosomal RNA (SSU rRNA) gene. In the present study, we investigated the morphological and molecular attributes of P. pulcher using standard methods. The morphology was studied based on observations of live materials, silver-impregnated preparations, and scanning electron microscopy. The morphological characteristics are as follows: body size 80–90 × 40–50 µm in vivo, shape broadly ellipsoidal, body cross-section ellipsoidal, about seven anterior spines and about seven posterior spines, approximately 21 somatic ciliary rows, one macronucleus and one micronucleus, and a single caudal cilium. The SSU rRNA gene tree supports a sister relationship of P. pulcher to the genus Apocoleps, not P. tesselatus.