Search

In Ariake Bay, Japan, two sciaenids Nibea albiflora and Pennahia argentata spawn in the same season and their larvae and juveniles are believed to co-occur. We developed a molecular method to identify larvae and early-stage juveniles of N. albiflora and P. argentata using multiplex polymerase chain reaction (PCR) due to difficulties of species identification using morphological keys and compared the ontogenetic distribution and feeding habits in larvae and early-stage juveniles of both species. N. albiflora spawn in the shallow water of the inner part of the bay, and P. argentata spawn in the deeper waters from the middle to the outer part of the bay. As a result of inter-species difference in their preferred spawning areas, P. argentata larvae were more common than N. albiflora in the southern part of the bay. The larvae of both species tended to emerge in shallower waters toward the inside of the bay and juveniles were observed exclusively in the lower reaches of the inflowing rivers, suggesting that larvae and juveniles could be successfully transported to their nursery ground or retained in the bay without seaward dispersion. In Ariake Bay, the maximum turbidity zone is around the mouth and estuarine areas of the rivers in the innermost part of the bay and these areas are important nursery grounds for both study species during their early life stages, especially the early juvenile stage. For N. albiflora , pre-flexion and flexion larvae fed exclusively on small copepods, mainly Oithona davisae , whereas post-flexion and juveniles fed mainly on a large copepod, Sinocalanus sinensis , and mysids. P. argentata larvae and juveniles consistently fed on copepods, mainly Paracalanidae. Both species consumed small prey throughout the larval stages and the smallest prey consumed by juveniles was larger than that consumed by larvae. The size of the largest prey consumed by larvae and juveniles of both species tended to increase throughout development. The similarity of morphological features and ontogenetic distribution patterns between species suggest that the observed differences in diet composition of both species may result from differences in selective feeding by larval and juvenile N. albiflora and P. argentata . [ABSTRACT FROM AUTHOR]

Abstract: Percomorpha has been described as the “(unresolved) bush at the top” of the teleostean phylogenies and its intrarelationships are intrinsically difficult to solve because of its huge diversity (>15,000 spp.) and ill-defined higher taxa. Patterns of facial nerves, such as those of the ramus lateralis accessorius (RLA), have been considered as one of the candidate characters to delimit a monophyletic group within the percomorphs. Six families of the suborder Percoidei (Arripidae, Dichistiidae, Kyphosidae, Terapontidae, Kuhliidae, and Oplegnathidae) and suborder Stromateoidei (including six families) share the unique pattern 10 of RLA and it has been suggested that those fishes form a monophyletic group across the two perciform suborders. To evaluate the usefulness of the RLA pattern 10 as a phylogenetic marker within the percomorphs, we newly determined whole mitochondrial genome (mitogenome) sequences for the 13 species having RLA pattern 10 and their putatively, closely-related species (5 spp.). Unambiguously aligned sequences (14,263bp) from those 18 species plus 50 percomrphs and two outgroups (total 70 species) were subjected to partitioned maximum likelihood and Bayesian analyses. The resulting trees clearly indicated that there were at least two independent origins of the unique facial nerve pattern: one in a common ancestor of Kyphosidae, Terapontidae, Kuhliidae, and Oplegnathidae and another one in that of the percoid Arripidae and Stromateoidei. Thus further detailed anatomical studies are needed to clarify the homology of this character between the two lineages. It should be noted that the latter two taxa (Arripidae and Stromateoidei) formed an unexpected, highly-supported monophyletic group together with Scombridae and possibly Chiasmodontidae and Bramidae, all lacking RLA pattern 10 (the former two are members of other perciform suborders Scombroidei and Trachinoidei, respectively). This novel, trans-subordinal clade has never been suggested by any morphological studies, although they share a common ecological characteristic, dwelling in the pelagic realm and often associated with long-distance migrations. [Copyright &y& Elsevier]

Abstract: Tetraodontiformes includes approximately 350 species assigned to nine families, sharing several reduced morphological features of higher teleosts. The order has been accepted as a monophyletic group by many authors, although several alternative hypotheses exist regarding its phylogenetic position within the higher teleosts. To date, acanthuroids, zeiforms, and lophiiforms have been proposed as sister-groups of the tetraodontiforms. The monophyly and sister-group status was investigated using whole mitochondrial genome (mitogenome) sequences from 44 purposefully-chosen species (26 sequences newly-determined during the study) that fully represent the major tetraodontiform lineages plus all the groups that have been hypothesized as being close relatives. Partitioned Bayesian analyses were conducted with the three datasets that comprised concatenated nucleotide sequences from 13 protein-coding genes (with and without, or with RY-coding, 3rd codon positions), plus 22 transfer RNA and two ribosomal RNA genes. The resultant trees were well resolved and largely congruent, with most internal branches being supported by high posterior probabilities. Mitogenomic data strongly supported the monophyly of tetraodontiform fishes, placing them as a sister-group of either Lophiiformes plus Caproidei or Caproidei only. The sister-group relationship between Acanthuroidei and Tetraodontiformes was statistically rejected using Bayes factors. These results were confirmed by a reanalysis of the previously published nuclear RAG1 gene sequences using the Bayesian method. Within the Tetraodontiformes, however, monophylies of the three superfamilies were not recovered and further taxonomic sampling and subsequent efforts should clarify these relationships. [Copyright &y& Elsevier]