Redescription of Paradiplozoon opsariichthydis (Jiang, Wu et Wang 1984) Jiang, Wu et Wang, 1989 (Monogenea, Diplozoidae).

Paradiplozoon opsariichthydis (Jiang, Wu et Wang, 1984) Jiang, Wu et Wang, 1989 (Platyhelminthes, Monogenea, Diplozoidae) is blood-feeding parasite from the gills of Asian cyprinid fish Opsariichthys bidens Günther, 1873. In this study, we present a morphological redescription of P. opsariichthydis neotype main morphological features e.g. size of body and clamps due to the fact that the type material is missing. We decided to supplement morphological descriptions by the relevant molecular data (internal transcribed spacer - ITS2) related to P. opsariichthydis adult worm isolates and other representatives of genus Paradiplozoon to cross verify our findings. In addition to that, this study also brings an attention to the host identification. Thus, parasite data were complemented by the determinant cytochrome oxidase b (cytb) sequences of its hosts. All novel sequences are deposited in GenBank. This combination of the morphological and molecular data related to both the parasite and its host seems to be the optimal approach to the general process of (re)description of highly host-specific parasitic organisms, which can then lead to a meaningful phylogenetic analysis.

Molecular and Morphological Diversity of the Oxymonad Genera Monocercomonoides and Blattamonas gen. nov.

Oxymonads are a group of flagellates living as gut symbionts of insects or vertebrates. They have several unique features, one of them being the absence of mitochondria. Diversity of this group is seriously understudied, which is particularly true for small species from the family Polymastigidae. We isolated 34 strains of oxymonads with Polymastigidae-like morphology from 24 host species and unused cesspits and sequenced the SSU rRNA gene. Our strains formed two clades in the phylogenetic tree with Streblomastix strix branching between them. This topology was also supported by a three-gene phylogenetic analysis. Despite considerable genetic differences between the clades, light and electron microscopy revealed only subtle differences. The larger clade is considered genus Monocercomonoides and the isolates belonging here were classified into three new species (including the first potentially free-living species), two previously described species, and three unclassified lineages. The smaller clade, here described as Blattamonas gen. nov., consists of three newly described species. Concomitantly with the description of Blattamonas, we elevate the Monocercomonoides subgenus Brachymonas to the genus level. Our study shows that, despite their conserved morphology, the molecular diversity of Polymastigidae-like oxymonads is broad and represents a substantial part of the diversity of oxymonads.

Redescription of Paradiplozoon hemiculteri (Monogenea, Diplozoidae) from the type host Hemiculter leucisculus, with neotype designation.

Paradiplozoon hemiculteri (Ling, 1973), a member of the Diplozoidae, parasitizes the gills of Asian fish. Not only is the type material unavailable for this species, the original description was poor and somewhat conflicting, and adequate molecular data were not available. What is more, the available morphological and molecular data are inconsistent and fluctuate significantly. Here, we present a redescription of P. hemiculteri based on morphological and molecular data from new isolates collected from the type host, the sharpbelly Hemiculter leucisculus (Basilewsky, 1855), captured at the neotype locality (Shaoguan, Guangdong Province, southern China); a neotype for P. hemiculteri was designated from this collection. The length and width of the body, buccal suckers, pharynx, attachment clamps, sickle and the central hook handle were all measured and the shape of the anterior and posterior part of the median plate and anterior and posterior joining sclerites accurately documented. Phylogenetic analyses based on the sequences of the second rDNA internal transcribed spacer (ITS2) indicated that all new samples clustered together and differed clearly from sequences attributed to P. hemiculteri, which are deposited in GenBank. Our results confirm that P. hemiculteri is the only diplozoid that has demonstrably been found on the gills of H. leucisculus to date.