Gynichthys diakidnus n. g., n. sp. (Digenea: Cryptogonimidae) from the grunt Plectorhinchus gibbosus (Lacépède, 1802) (Perciformes: Haemulidae) off the Great Barrier Reef, Australia

Abstract

Gynichthys diakidnus n. g., n. sp. (Digenea: Cryptogonimidae) is described from the fish Plectorhinchus gibbosus (Lacépède) (Perciformes: Haemulidae) off Heron and Lizard Islands on the Great Barrier Reef, Australia. The monotypic Gynichthys n. g. is distinguished from all other cryptogonimid genera by the combination of a fusiform body, the lack of oral spines, a forebody that occupies approximately half or more of the body length, a deeply lobed ovary, opposite to slightly oblique testes, a seminal vesicle that is confined mainly in the forebody and the presence of multiple gonotyls in the form of two small slightly muscular pores or pseudosucker-like structures in the mid-line well anterior to the ventral sucker. Bayesian inference analysis of LSU rDNA data revealed that G. diakidnus n. sp. grouped relatively distant to species of the cryptogonimid genus Oligogonotylus Watson, 1976, which also have multiple gonotyls, suggesting that the presence of multiple gonotyls is homoplasious and has thus at least evolved twice in the family. The secondary structure of the internal transcribed spacer 2 (ITS2) rDNA region was inferred for G. diakidnus using minimum free energy and homology modelling algorithms. A four helix model was inferred with helices I and IV being relatively short (<30 nucleotides) and helix three being the longest; this structure is homologous with that observed for other digeneans and eukaryotes in general.

Two new Stephanostomum-like cercariae (Digenea: Acanthocolpidae) from Nassarius dorsatus and N. olivaceus (Gastropoda: Nassariidae) in Central Queensland, Australia

“…The optimal secondary structures inferred here for these putative acanthocolpid cercariae also agree with the four domain model of the ITS2 rDNA region using minimum free energy folding algorithms reported for other digenean families (Morgan & Blair 1998). All four of the helices in the models for these two cercariae are of similar length and structure to that of the general digenean structure reported by Morgan & Blair (1998) and Miller & Cribb (2009).…”

A molecular phylogenetic appraisal of the acanthostominesAcanthostomumandTimoniellaand their position within Cryptogonimidae (Trematoda: Opisthorchioidea)

“…Presently, more than 50 cryptogonimid taxa have been recorded from fishes belonging to the Lutjanidae and Haemulidae of the IW-P ( Miller & Cribb, 2007b ; Cribb et al, 2016 ), reflected in the phylogenetic topology revealed in this study; e.g., the genera Beluesca , Varialvus , Caulanus , Latuterus , Siphomutabilus , Metadena , Chelediadema , and Gynichthys ( Fig. 2 ) ( Miller & Cribb, 2007c ; Miller & Cribb, 2009 ; Miller & Cribb, 2013 ; Miller et al, 2010a ; Miller et al, 2010b ; Miller, Bray & Cribb, 2011 ; Overstreet, Cook & Heard, 2009 ). Furthermore, Adlardia novaecaledoniae has been found in Nemipteridae from the Indo-West Pacific ( Miller et al, 2009 ).…”

Cryptic species of Euryakaina n. g. (Digenea: Cryptogonimidae) from sympatric lutjanids in the Indo-West Pacific

“…The secondary structure of the ITS2 rDNA region for species of the new genus was also inferred to explore the homology of the structures with that recently predicted for other cryptogonimids (Koetschan et al, 2010;Miller & Cribb, 2009c). We then used comparative analyses of the aligned secondary structures of the species reported here to investigate the numbers of compensatory base changes (CBCs) and hemi-CBCs that may exist between these taxa.…”