Lizardfish Species Research Articles

Comparative ontogeny and phylogenetic relationships of eight lizardfish species (Synodontidae) from the Northwest Pacific, with a focus on Trachinocephalus monophyly.

Lizardfish (Aulopiforms: Synodontidae), distributed broadly in temperate to tropical waters, are represented globally by 83 species across four genera, with 10 species in Korea. Despite these numbers, few studies have been conducted on the early life history of lizardfishes compared to their adult counterparts. Thus, we conducted molecular identification of 123 Synodontidae larvae collected from the Northwest Pacific (Korea Strait, Yellow Sea, East China Sea, and East Sea) between June 2017 and July 2021, using mitochondrial DNA COI and 16S rRNA sequences. Significant morphological differences were observed in the larvae and juvenile, including variation in melanophore, count, morphometric characteristics, and body shape. The morphological traits of eight species (Harpadon nehereus, Saurida macrolepis, Saurida wanieso, Saurida sp., Synodus hoshinonis, Synodus kaianus, Synodus macrops, and Trachinocephalus trachinus) served as vital data for interpreting the phylogenetic relationships within the Northwest Pacific Synodontidae. Ultimately, the identification key revealed by this study will enable accurate identification of Synodontid larvae and juveniles, and further facilitate our understanding of the phylogenetic relationships within this family.

Population Dynamics and Stock Assessment of Two Lizardfish Species in the Southern Red Sea Coasts, Foul Bay, Egypt

Population Dynamics and Stock Assessment of Two Lizardfish Species in the Southern Red Sea Coasts, Foul Bay, Egypt

Distribution of 210Po in body organs of bigeye scad and greater lizardfish species at Binh Thuan, Vietnam

Distribution of 210Po in body organs of bigeye scad and greater lizardfish species at Binh Thuan, Vietnam

Species delineation of lizardfishes, Saurida pseudotumbil Dutt and Sagar, 1981 and Saurida tumbil (Bloch, 1795) using multivariate tools

Morphometric characters of two species of lizardfishes viz.,Saurida pseudotumbil Dutt and Sagar, 1981 and Saurida tumbil (Bloch, 1795), were studied to delineate the species using multivariate techniques. Specimens were collected from Parangipettai and Cochin waters, southern India, for recording data on 21 morphometric characters. Principal component analysis (PCA) was done after log transformation and the first three components explained 93.36% of the total variation. The most important morphometric characters determined using the eigenvectors (coefficients) of these components were post-orbital length, snout to pectoral, snout to pelvic, snout to anal, anal fin base and dorsal fin base, which showed high loading (≥0.8) in the three components. The overlapping ratio between these species ranged from 42.59 to 89.28%. The PCA data cloud of S. pseudotumbil and S. tumbil also reflected the same trend. Therefore, canonical analysis of principal coordinates (CAP) was done which clearly separated the species with maximum case allocation success (100%) for both S. pseudotumbil and S. tumbil, which clearly showed that both the species are different.

A New Species of Lizardfishes of Genus Trachinocephalus from the Western Indian Ocean (Synodidae)

Trachinocephalus atrisignis sp. n. is described from three specimens caught in the western Indian Ocean near Socotra Island. It differs from other representatives of the genus by a saturated black spot on the dorsal fin tip, the shape of the snout and lower jaw, and somewhat lower number of vertebrae and lateral line scales.

Melanization of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae)

Investigating the alimentary tract in several species of lizardfishes (Synodontidae, Teleostei) of the genera Saurida, Synodus and Trachinocephalus, from various sites of their distribution, revealed melanization of the tract wall. This phenomenon was observed in several species of the genus Saurida, but not in the other two genera. This melanization is caused by layers of melanosomes rich in melanin granules and deposited within the connective tissue of the submucosa, between the muscular wall and the muscularis submucosa. From this site this black submucosa extends into the folds of the mucosa. In S. tumbil and S. filamentosa, the entire alimentary tract is black, whereas in S. macrolepis only the stomach is partially or entirely black. This phenomenon and its possible importance are discussed.

Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae)

AbstractFishelson, L., Golani, D., Russell, B., Galil, B. and Goren, M. 2012. Comparative morphology and cytology of the alimentary tract in lizardfishes (Teleostei, Aulopiformes, Synodontidae). —Acta Zoologica (Stockholm) 93: 308–318.This study compares the morphology and cytology of the alimentary tract in several species of lizardfishes (Synodontidae, Teleostei) of the genera Saurida, Synodus, and Trachinocephalus, in relation to their diets and bathymetric distribution. All the studied species feature a large, pouch‐like stomach, with the intestine beginning at the stomach’s anterior apex, adjacent to the esophageal opening. In the more ‘microphagous’Synodus spp. and Trachinocephalus, the intestine bends twice before reaching the anus, whereas in the more ‘macrophagous’Saurida spp., the intestine extends straight to the anus. The species differ also in the number and form of their pyloric ceca, the length of the intestine and in the percentile relationship between stomach length and standard body length. Along the alimentary tract folds and villi protrude into the lumen, their numbers differing on various sites of the tract. Three cell types make up the gastric gland system: (1) pyramidal cells forming the tubular gastric glands in the lamina propria; among them are large, pale secretary cells; (2) groups of neck cells that surround the pits of the tubules; and (3) groups of large and granule‐rich cells at the end portion of the stomach. All species are carnivorous and uniform in morphology, the differences in the alimentary tract found between the more shallow‐water species of Synodus and Trachinocephalus, and the deeper‐dwelling Saurida, seem to be only partly correlated with the differences in diet.

Comparative morphology and cytology of the eye, with particular reference to the retina, in lizardfishes (Synodontidae, Teleostei)

Fishelson, L., Delarea, Y. and Goren, M. 2012. Comparative morphology and cytology of the eye, with particular reference to the retina, in lizardfishes (Synodontidae, Teleostei). —Acta Zoologica (Stockholm) 93: 68–79. The retinas of nine species of lizardfishes (Synodontidae) are composed of double cones, single cones, and rods. The cones are 16–28 μm long, and their number in the fundus of adult Synodus variegatus reaches ca. 32,900 mm2 (varying from ca. 300,000 to ca. 390,000 in a 10 mm2 of the retina), while in Saurida spp., they number ca. 12,000–14,000/mm2. The cone ellipsoids are with up to 600 mitochondria, 0.5–1.6 μm in diameter. The rods are 30–50 μm long; their outer segments 0.6–1.2 μm thick and 15–18 μm long; their inner segments elongated. Their number varies from 15 to 128 million/retina. In fish of similar dimensions but of different species, the number of visual cells in the retina differs. In all species, the eyes increase from 2.0 mm in diameter in the smallest fish studied to 12 mm in the largest one. With eye growth, the retina in the various species increases from ca. 3.8 mm2 in the smallest fish to ca.160.0 mm2 in the large Saurida macrolepis. The possible ecological aspects of the observed phenomena are discussed.

Environmental influences on the replenishment of lizardfish (family Synodontidae) in Caribbean Panama

Lizardfish (family Synodontidae) are little studied despite their potentially important predatory role in epibenthic coral reef communities. The present study documented the temporal and spatial larval supply patterns of five Caribbean lizardfish species together with environmental variables (solar radiation, rainfall, water temperature, onshore-offshore winds, alongshore winds and wind-induced turbulence) to examine: (1) whether species within the same family respond differently to their developmental environment and (2) if larval supply in year-round warm waters is influenced by climatic changes. To address these questions, late-stage larvae of Synodus foetens, Synodus intermedius, Synodus poeyi, Saurida suspicio and Saurida brasiliensis were collected in replicate light traps in three different reef habitats (back-reef, lagoon and exposed) in the San Blas Archipelago, Panama, over 18 consecutive lunar months. Although replenishment of lizardfish occurred year-round, the temporal and spatial supply patterns were species-specific: S. foetens, S. intermedius and S. poeyi were most abundant during the dry season while S. suspicio and S. brasiliensis were most prevalent during the wet season. When seasons were analysed separately, water temperature explained 39 and 26% of the variance in light trap catches of S. foetens and S. intermedius, respectively, in the dry season while wind-induced turbulence accounted for 25% of the variability in S. suspicio and S. brasiliensis catches during the wet season. These findings stress the importance of analysing larval supply in conjunction with environmental data at a high taxonomic resolution to better understand the mechanisms that drive replenishment in reef systems at low latitudes.

CDNA cloning and complete primary structures of myosin heavy chains from brushtooth lizardfishSaurida undosquamisand wanieso lizardfishS. waniesofast skeletal muscles

The complete cDNA sequences encoding predominant types of myosin heavy chain (MYH) in the fast skeletal muscle were, determined for brushtooth lizardfish Saurida undosquamis and wanieso lizardfish S. wanieso, which are used as materials for preparing high-quality surimi-based products. The cDNA consisted of 5973 and 5987 bp, respectively, and both encompassed an open reading frame encoding a polypeptide of 1936 amino acid residues. Brushtooth and wanieso lizardfish MYH showed the amino acid, sequence identity of 92–93% to white croaker MYH, which was higher than that of 90% to walleye pollack MYH. The putative binding sites for ATP, actin, and regulatory and essential light chains in the subfragment-1 region of brushtooth lizardfish MYH exhibited a high identity with white croaker counterparts as well as the sequences of subfragment-2 and light meromyosin. In contrast, phylogenetic tree, constructed by the neighbor-joining method based on mitochondrial 16S rRNA gene, revealed that the two lizardfish species formed a cluster with walleye pollack, which was paraphyletic with white croaker. Therefore, a good reputation for lizardfish and white croaker to have a high thermal-gel forming ability seemed to be reflected by MYH rather than biolgoical similarity as revealed by the mitochondrial 16S rRNA gene.

Heteromorphic sex chromosomes of lizardfish (Synodontidae): focus on the ZZ-ZW1W2 system in Trachinocephalus myops.

The karyotype and DNA content of four lizardfish species (family Synodontidae), that is, Saurida elongata, Synodus ulae, Synodus hoshinonis and Trachinocephalus myops, were analyzed. The karyotype of T. myops significantly differed from that of the other three species having diploid chromosome number of 48 with mainly acrocentric chromosomes and the ZZ-ZW sex chromosome system. The chromosome number of male T. myops was 2n = 26, while that of female T. myops was 2n = 27. The karyotype consisted of 11 pairs of metacentrics, one pair of acrocentrics and, in addition, two large metacentrics in the male and a single large metacentric, a distinctly small subtelocentric and a microchromosome in the female. C-banding demonstrated that in the female the subtelocentric chromosome and the microchromosome were heterochromatic. The karyotype of T. myops was thought to be derived from a 48 chromosome type synodontid fish through the involvement of Robertsonian rearrangement; the rearrangement of the sex chromosomes proceeded during karyotype evolution. Among the chromosomes, the large metacentrics were determined to be neo-Z (a fusion of the original Z and an autosome), the microchromosomes the W1 (originally W), and the subtelocentric chromosomes the W2 (derived from an autosome pair). The miniaturization of W1 and W2 chromosomes and their heterochromatinization suggested that sex chromosomes in this species have been already highly differentiated. The findings on DNA content implied that the karyotype of T. myops evolved by centric fusion events without loss in DNA amount.

Seasonal Variation of Gel-forming Characteristics of Three Lizardfish Species

Seasonal Variation of Gel-forming Characteristics of Three Lizardfish Species

Identification of Proteolytic Activities of Gel-Degrading Factors in Three Lizardfish Species.

The inhibitory effects of several selected proteinase inhibitors, soybean trypsin inhibitor, leupeptin, antipain, E-64, NEM and EDTA, on myosin heavy chain (MHC) degradation of unwashed and washed meat gels from three lizardfish species, maeso or true lizardfish Saurida undosquamis, wanieso Saurida wanieso, tokageeso or shortfin lizardfish Saurida elongata, were investigated in order to identify the proteolytic activities of gel-degrading factors (GDFs) existing in mat. It was apparent that the proteolytic activities of GDFs responsible for MHC degradation of meat gels from all species at 40°C resulted from two myofibril-associated (Mf) type proteinases, mainly of serine proteinase and slightly of cysteine proteinase. In addition, as indicated by the amino acid patterns obtained from TCA-soluble fraction of meat gels with the presence of various inhibitors, these proposed proteinases were not distinct in these three species. With regard to the MHC degradation at 60°C, the proteolytic activity present in GDFs of maeso, proposed as myofibril-associated gel degrading factors (Mf-GDFs), belonged to cysteine proteinase while that of wanieso and tokageeso were sarcoplasmic-type serine proteinases. The Mf-GDF corresponding to the MHC degradation at 60°C, which occasionally occurs in wanieso meat gel, showed the proteolytic activities of serine proteinase.

The Gel-Forming Characteristics of Lizardfish.

The gel-forming characteristics of unwashed and washed meat from three lizardfish species (maeso Saurida undosquamis, wanieso Saurida wanieso, and tokageeso Saurida elongata) were investigated at various heating temperatures from 30 to 80°C for 20 minutes and 2hours. Judging from evaluation of gel strength by tensiometer and a folding test accompanied by degradation of myosin heavy chain (MHC) by SDS-PAGE analysis, the gel degradation of unwashed meat gels occurred at 40, 60, and 70°C in tokageeso, while it occurred at 60 and 70°C in maeso and at 60°C in wanieso. Washing of meat did not improve the gel strength or MHC degradation of meat gel at 40°C in tokageeso or at 60°C in maeso. Moreover, washing of meat showed an enhancing effect on MHC degradation of maeso and wanieso meat gels at 40°C. These findings indicate that the gel-degrading factors (GDFs) which existed in these species were not only sarcoplasmic (Sp) and myofibrillar (Mf) type active at 60°C but also Mf type active at 40°C and Sp type active at 70°C.

マエソ属魚類3種の筋肉たんぱくの電気泳動像の比較

The cellulose acetate electrophoretic patterns of three species of lizard fishes, Saurida undosquamis, S. tumbil and S. elongata were observed. The property of muscle proteins soluble in salt solution of low ionic strength in each species was analyzed for the mobility and percentage of each component, and the number of components in the electrophoretic pattern. Although the differentiation among these three species was distinct, S. undosquamis was more similar to S. tumbil than to S. elongata, and S. tumbil was intermediate between S. undosquamis and S. elongata in this character. This trend was parallel with that of the morphological evidence. It is also verified that electrophoretic patterns of muscle proteins were very stable for at least 45 days, when the specimens were stored at -20°C.