Exon-primed intron-crossing (EPIC) polymerase chain reaction (PCR) was applied to ribosomal protein genes of long-spined sea urchin species of the genus Diadema. Amplicon size differences among three species (D. clarki, D. setosum, and D. savignyi) were observed in 40S ribosomal protein S3, to which large indels in the intron were primarily responsible. This may be a simple and diagnostic nuclear DNA marker for hybridization study in Diadema.

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The common freshwater shrimp Palaemon paucidens is recognized as a species complex comprising three genetically distinct types, referred to as A, B, and C. The B type is further subdivided into two subtypes, B-I and B-II, with B-I being described as the new species P. septemtrionalis. In this study, we designed a PCR primer pair based on the nucleotide sequence of the cDNA encoding the insulin-like androgenic gland hormone (IAG) of P. paucidens. PCR products were cloned and the nucleotide sequences from A, B (including both B-I and B-II subtypes), and C types were determined. The PCR products encompassed the entire exon 1, the complete intron 1, and partial exon 2. Phylogenetic analysis revealed two largely divergent clades, designated as IAG1 and IAG2 paralogs. Substantial nucleotide sequence differences were observed among the three types in IAG1 and between B and C types in IAG2. Notably, no IAG2 was detected in A type samples, and no apparent difference was observed between the B-I and B-II subtypes in either paralog.

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Juveniles of the Japanese turban shell Turbo sazae were reared under static and flowing water conditions by feeding cabbage alone for two years. The growth of the reared individuals was comparable to that of reared juveniles fed formulated diets and/or algae and to that of wild juveniles, indicating that the cabbage could be an alternative or supplemental food source for rearing the turban shells. Survival rates were approximately 60 % after one year and decreased to 20 % after two years. Spine formation was not observed in all individuals. Factors involved in the spine formation were discussed.

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A gilled (final) stage phyllosoma larva (BL = 10.8 mm) of scyllarine slipper lobster was collected in the western North Pacific (29º 07' N, 129º 06' E). Database homology searches and phylogenetic analysis using partial mitochondrial 16S rDNA and COI sequences failed to identify the species but indicated that this larva belonged to the genus Eduarctus. Although this phyllosoma was morphologically very similar to the final stage larva of Eduarctus modestus, the nucleotide sequences of this specimen differed substantially from those of E. modestus.

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A final stage scyllarine phyllosoma larva collected in the western North Pacific (27º 00N, 130º 00E) was identified as Crenarctus bicuspidatus by mitochondrial 16S rDNA sequence analysis. This larva was characterized by having a small body length (BL = 14.0 mm) for a final stage, a round cephalic shield, and long lateral spines on the telson.

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We have performed DNA barcoding and morphological analyses for scyllarine phyllosoma larvae. Five phyllosoma larvae having subrectangular-shaped cephalic shields with straight posterior margins were selected from plankton samples collected in the central North Pacific. Mitochondrial 16S rDNA sequence analysis indicated Crenarctus crenatus to be the closest species for these larvae. Based on the nucleotide sequence divergence (K2P: 1.66 ± 0.61 %) between these five larvae and C. crenatus and the geographic distribution of C. crenatus restricted to the South Pacific, we tentatively determined these larvae to be a subspecies of C. crenatus (designated as C. crenatus sub sp. 1).

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Of scyllarine phyllosoma larvae collected in the western North Pacific, a larva with a large body length (28.1 mm) for a subfinal stage and having a large kidney-shaped cephalic shield was selected. Mitochondrial 16S rDNA and COI sequence analyses indicated this larva to belong to the genus Galearctus but failed to identify species. We tentatively designated the species of this larva as Galearctus sp-A.

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Of phyllosoma larvae of the subfamily Scyllarinae collected in the western North Pacific, 19 individuals (BL = 10.1‒38.5 mm) having an onion-shaped cephalic shield were selected. Phylogenetic analysis using partial mitochondrial 16S rDNA and COI sequences revealed that these larvae were of Galearctus lipkei. Gilled (final) stage phyllosoma larvae (BL = 34.2‒38.5 mm) of G. lipkei were the largest in this subfamily reported to date.

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Four species (Chelarctus aureus, C. crosnieri, C. cultrifer, and C. virgosus) have been described in the genus Chelarctus of the subfamily Scyllarinae, of which mid to final stage phyllosoma larvae in three species (C. aureus, C. crosnieri, and C. virgosus) have been reported. Ueda et al. (2021) found phyllosoma larvae morphologically assigned to the genus Chelarctus but having distinct DNA sequences from the above four species, designating ?Chelarctus sp-1. Additional specimens (n = 8) of mid to final stage phyllosoma larvae of this species were collected in the western North Pacific. The 16S rDNA sequence data supported ?Chelarctus sp-1 to be a member of the genus Chelarctus. Based on the shape of the cephalic shield, the ratio of the cephalic shield width and length, length of posterolateral spines on the telson, and body size of each stage, mid to final stage phyllosoma larvae of ?Chelarctus sp-1 could be discriminated from those of the other species of the genus reported to date.

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A gilled (final) stage slipper lobster phyllosoma larva (BL = 23.8 mm) collected in the western North Pacific (27º N, 130º E) was determined to be Chelarctus aureus using mitochondrial 16S rDNA sequence analysis. Morphological characteristics of this larva agreed well with the final stage larva of this species reported previously (Ueda et al. 2021). Mid to final stage phyllosoma larvae of this species can be distinguished from those of the other congeneric species based on their large cephalic shield width and length ratio (1.404‒1.587) and the sub-rectangular shape cephalic shield.

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Thirty-four exon-primed intron-crossing PCR (EPIC-PCR) primer pairs for amplifying ribosomal protein gene introns were tested using eight individuals from four Thunnus tuna species. Only two pairs failed to amplify fragments for all individuals. Whenever amplicons were observed, no apparent fragment length difference was observed between species. Possible allelic variation due to fragment length polymorphism was observed at 13 loci.

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Eight fan lobster species have been described in the genus Ibacus, two of which (Ibacus ciliatus and I. novemdentatus) are observed in Japanese waters. Complete larval development in the laboratory has been successfully achieved for these two species. However, the available information on phyllosoma larvae of these species in plankton samples is fragmental, insufficient to match with the reared specimens and to elucidate the distribution and recruitment of the larvae. This review provides a comprehensive overview of the larval development, species identification, distribution, and recruitment of Ibacus phyllosoma.

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The PCR-amplified partial mtDNA cytochrome c oxidase subunit I (COI) gene of the Aesop slipper lobster (Scyllarides haanii) was subjected to direct nucleotide sequencing and clone library-based nucleotide sequencing analyses. A total of 35 clones were sequenced, of which 16 were determined to be the authentic mtDNA COI sequence (763 bp) of this individual. Nucleotide sequences of 10 clones that differed by one to three nucleotides from the authentic sequence were designated as variant artifacts by PCR-cloning. Seven haplotypes were obtained from the remaining nine clones, which differed by 70 to 112 nucleotides from the authentic COI sequence and were determined to be nuclear mitochondrial pseudogenes (NUMTs). Double peaks were observed in the electropherogram obtained by direct nucleotide sequencing, and the resulting nucleotide sequence was substantially different from both the authentic mtDNA COI and NUMT sequences. It was shown that the electropherogram obtained by direct nucleotide sequencing appeared to be a mixture of signals from the authentic mtDNA COI and NUMTs sequences.

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A juvenile spiny lobster (50.6 mm in body length, 20.6 mm in carapace length) was collected off Usujiri (41°93'N, 140°96'E), Hakodate, Japan, November 2023. Morphological analysis and DNA barcoding using mitochondrial 16S rDNA sequence unambiguously indicated this juvenile to be the Japanese spiny lobster Panulirus japonicus. This is the second report of this species from Hokkaido, but the first with species identification by DNA analysis.

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