Lateral Line Scales Research Articles

Revisiting the description of Atractoscion macrolepis (Perciformes: Sciaenidae): Another argument for comprehensive taxonomy

Atractoscion macrolepis was described as a species separate to A. aequidens, distinguished by a geographically-separated distribution, genetic evidence and a diagnostic meristic character: the number of pored lateral line scales. However, the distinction of these species and description of A. macrolepis were based on the examination of a limited number of specimens, some of which were incorrectly catalogued and possibly wrongly identified. Moreover, earlier data, demonstrating the overlap of the supposedly diagnostic character, were overlooked or not considered fully. The present study aimed to reconsider the distinction of these two species and to highlight characters for identification, using a more extensive representation of specimens, additional character sets and multivariate analyses. Seven meristic characters, 24 morphometric measurements and nine otolith variables were examined from up to 33 specimens of A. aequidens and 52 specimens of A. macrolepis. These were compared among the species and subjected to univariate and multivariate analyses, including Principal Component Analyses (PCAs) and Discriminant Function Analyses (DFAs). No meristic characters, including the number of lateral line scales, could distinguish the species, with modes being identical or with nodes differing, but ranges overlapping. While the PCA of size-transformed morphometric data revealed some separation of the two species, the DFA indicated significant and reliable discrimination. Considering the otolith variables, the PCA showed weak separation of the two species, while fair discrimination was observed in the DFA. ANOVAs indicated a number of significant differences for some transformed otolith measurements, but there were no clear trends with respect to proportions that would discriminate the species. Further exploration of those morphometric variables highlighted as contributing to separation in the PCA and DFA provided a number of variables that, when expressed as a proportion of SL and used in combination, discriminate A. aequidens and A. macrolepis: HL, MCL, PFL, AFL and PLFL. The present study does not contest the taxonomic status of A. macrolepis, the distinction of which has been demonstrated repeatedly, but does refute the characters regarded as diagnostic. In light of this, an updated key is provided for the five species of the genus. The study demonstrates the value of increased specimen representation and having data fully available rather than in summary.

A new species of Opsariichthys (Teleostei, Cypriniformes, Xenocyprididae) from Southeast China.

Opsariichthysiridescens sp. nov. is described from the Qiantang and Oujiang rivers in Zhejiang Province and a tributary of the Yangtze River adjacent to the Qiantang River. It is distinguished from congeners by the following combination of morphological features: no obvious anterior notch on the tip of the upper lip; 45-52 lateral-line scales; 18-21 pre-dorsal scales; two rows of pharyngeal teeth; a maxillary extending to or slightly beyond the vertical anterior margin of the orbit in adult males; a pectoral fin extending to the pelvic fin in adult males; nuptial tubercles on the cheeks and lower jaw of males, which are usually united basally to form a plate; uniform narrow pale pink cross-bars on trunk and two widening significantly on caudal peduncle. Its validity was also supported by its distinct Cyt b gene sequence divergence from all congeners and its monophyly recovered in a Cyt b gene-based phylogenetic analysis.

Meristic co-evolution and genomic co-localization of lateral line scales and vertebrae in Central American cichlid fishes.

Meristic traits are often treated as distinct phenotypes that can be used to differentiate and delineate recently diverged species. For instance, the number of lateral line scales and vertebrae, two traits that vary substantially among Neotropical Heroine cichlid species, have been previously suggested to co-evolve. These meristic traits could co-evolve due to shared adaptive, developmental, or genetic factors. If they were found to be genetically or developmentally non-independent, this might require a more general re-evaluation of their role in evolutionary or taxonomic studies. We expanded a previous analysis of correlated evolution of meristic traits (lateral line scales and vertebrae counts) in these fishes to include a range of phylogenetic reconstructions as well as the analyses of 13 Nicaraguan Midas cichlid species (Amphilophus spp.). Additionally, we performed qualitative traits locus (QTL) mapping in a F2 laboratory-reared hybrid population from two ecologically divergent Midas cichlid fish species to discover and evaluate whether genomic co-segregation might explain the observed patterns of meristic co-evolution. Meristic values for these traits were found to morphologically differentiate some species of the Midas cichlid adaptive radiation. Our QTL analysis pinpointed several genomic regions associated with divergence in these traits and highlighted the potential for genomic co-segregation of the lateral line and vertebrae numbers on two chromosomes. Further, our phylogenetic comparative analyses consistently recovered a significant positive evolutionary correlation between the counts of lateral line scale and vertebrae numbers in Neotropical cichlids. Hence, the findings of genomic co-segregation could partially explain the co-evolution of these two meristic traits in these species. Continuing to unravel the genetic architecture governing meristic divergence helps to better understand both trait correlations and the utility of meristic traits in taxonomic diagnoses and how traits in phenotypes might be expected to co-evolve.

Scale Characteristics of Six Fish Species of the Genus Cyprinion (Teleostei: Cypriniformes): A Microscopic Analysis.

This study investigated the morphological characteristics of scales in six Cyprinion species, using light and scanning electron microscopy focusing on key features such as scale type, key scales, lateral line scales, radius/radii, rostral margin, focus, circuli, lepidonts, tubercles, and scale indices. The research analyzed the scales using ultramicroscopy and light microscopy imaging, categorizing them based on size classes and body regions. The morphological variations in scale characteristics were examined across different species, regions, and size classes. Notable findings included the tetra-sectioned form of scales, representing a unique characteristic of the Cyprinion genus. Morphological changes in scale features were observed with fish growth, particularly in the overall shape, focus shape, and size. Quantitative analysis revealed variations in average relative scale length and width among different species, regions, and size classes. The study utilized canonical discriminant analysis for multivariate assessment, classifying the species into distinct groups based on morphometric indices. The findings contribute to the understanding of scale morphology in Cyprinion species and exploring morphological variation between the examined species.

Parallel phenotypic evolution of two independent cavefish lineages of Astyanax mexicanus (De Filippi, 1854) (Characiformes: Characidae)

Abstract Astyanax mexicanus offers a unique model for studying parallel evolution, with cave-dwelling forms arising from at least two distinct surface lineages. Here, we examined repeated evolution in the two cave-adapted lineages across four phenotypic datasets: (i) meristic data; (ii) ecomorphological data; and geometric morphometric data for (iii) head and (iv) premaxillary bone shape. Additionally, we assessed the association of these phenotypes with their phylogenetic history. Certain traits exhibited evidence of parallel evolution for the cave ecotype across lineages, such as increased maxillary tooth count, reduced lateral line scale count, and shorter ascending process of the premaxillary bone. Geometric morphometric data showed a phenotypic divergence gradient in head shape between cave and surface populations, with the strongest divergence between Sierra de El Abra and surface populations and with less differentiation between surface populations and caves from Sierra de Guatemala and Micos. Cave populations that hybridize with surface populations (e.g. Micos) displayed the greatest overlap with the surface ecotype. There was a similar divergence gradient for premaxillary bone shape, but with weaker differentiation between cave and surface ecotypes. This evidence of repeated evolution in several cave traits emphasizes the significance of selective pressures exerted by the environment on the evolution of cave ecotypes.

Threatened fishes of the world: Schizothorax (Racoma) biddulphi (Günther, 1876) (Cyprinidae)

In order to study the individual biology of endemic fish in China, lay a foundation for the conservation of its germplasm resources, and consolidate the basic biological data of endemic fish in the world. According to the ethical code and fishing permit, 21 samples of Schizothorax (Racoma) biddulphi (Günther, 1876) were collected from the Muzati River in Tarim River system from 2021 to 2022, and their morphological characteristics, age identification and anatomical observation were analyzed by classical biological methods. S. biddulphi has a long body, a conical head, a pointed snout and a lower mouth. Requires 2 pairs. The scales are small and neatly arranged; Bare or scaly chest; The lateral line scale is slightly larger. The lateral line is complete. The correlation equation between body length and body weight is: W = 4.148 × 10-5L2.791. There were 5 kinds of age identification materials: 15+ for lapillus and asteriscus, 14+ for vertebra, 11+ for opercular bone, and 9+ for anal scale. The peritoneal wall of S. biddulphi is black; The tooth type is 2·3·5-5·3·2; The gill harrow was 11~13 for laymen and 15~18 for experts. Diphysocyte; Gallbladder oval; The number of vertebrae is 4+42-43+1, and the number of ribs is 23 or 24. S. biddulphi is a special species in the Tarim River system, and its evolutionary adaptation is closely related to the uplift of the Qinghai-Tibet Plateau.

Neomerinthe ornithoptera, a new species of scorpionfish (Teleostei: Scorpaenidae) from the southwestern Pacific Ocean, with a reassessment of the diagnosis for N. pallidimacula (Fowler 1938)

Neomerinthe ornithoptera n. sp., described on the basis of three specimens from Fiji and the Wallis and Futuna Islands, southwestern Pacific Ocean, was previously reported as Neomerinthe pallidimacula (Fowler 1938), due to its characteristic lack of both lateral lacrimal and second preopercular spines. The new species is clearly distinguished from Indo-Pacific congeners, including N. pallidimacula, by the following combination of characters: pectoral-fin rays 18; scale rows in longitudinal series 44 or 45; pored lateral-line scales 23; scale rows above lateral line 6 or 7, below lateral line 12, between sixth dorsal-fin spine base and lateral line 5, between last dorsal-fin spine base and lateral line 5; upper gill rakers 6, lower gill rakers 13, total gill rakers 19; longitudinal ridge on lateral surface of maxilla absent; many small cycloid scales on base of pectoral fin and ventral surface of body between isthmus and posterior to pelvic fin; pectoral-fin ray length 37.6–40.0% of SL; first anal-fin spine length 6.9–8.5% of SL; second anal-fin spine length 23.3–25.5% of SL; third anal-fin spine length 22.7–23.1% of SL; pelvic-fin spine length 17.9–18.1% of SL; longest pelvic-fin soft ray length 26.6–29.2% of SL; and several lower pectoral-fin rays markedly elongated. In addition, the diagnosis of N. pallidimacula shows the species to be similar to Neomerinthe bucephalus (Alcock 1896), although distinguished from the latter by the following features: upper-jaw length 25.0% of SL; maxilla depth 8.2% of SL; eleventh dorsal-fin spine length 5.7% of SL; and 22 pored lateral-line scales.

Redescription of Cyprinion muscatense (Teleostei: Cyprinidae) with the first phylogenetic analysis of the genus.

Members of the genus Cyprinion (Cypriniformes: Cyprinidae) are found in the Indus River basin west to the Arabian Peninsula and the Tigris-Euphrates River drainages (Persian Gulf basin). The taxonomic status of Cyprinion including Cyprinion muscatense is poorly understood when compared to other cyprinid genera. C. muscatense has been considered as a member of the Cyprinion watsoni-microphthalmum group and a valid species endemic to the Arabian Peninsula. Here, we redescribe C. muscatense based on an integrative morphological and molecular approach and freshly sampled material from several localities in the Oman Mountains ecoregion. The results showed that C. muscatense is distinguished from the other Cyprinion species in the Arabian Peninsula by having a short, thin, and slightly serrated last unbranched dorsal fin ray; the lower number of circumpeduncular scales; lateral line scales; and also scales between the lateral line and the dorsal-fin origin. Subterminal mouth, presence of one pair of small barbels at the mouth corner, 3-4 unbranched and 9½-10½ dorsal-fin branched rays, 12-14 pectoral-fin rays, 7-8 pelvic-fin rays, 2-3 unbranched and 6½-7½ branched anal-fin rays, and 37-40 lateral line scales are other morphological characteristics of C. muscatense. C. muscatense is also well distinguished by molecular characters among its congeners. The first molecular phylogenetic analysis of the genus, covering all currently recognized Cyprinion species except for C. watsoni, is also presented. C. muscatense is resolved as the sister species to another endemic fish of the Arabian Peninsula Cyprinion mhalense, with a Kimura-2-Parameter model distance of 5.3%.

Garra hexagonarostris, a new labeonine fish (Teleostei: Cyprinidae) from the Chindwin basin, Manipur, Northeast India, and a critical review on the taxonomic status of G. minimus, G. alticaputus, G. nigricauda, G. kimini, and G. tyao.

Garra hexagonarostris, a new member of the proboscis species group, is described from the Chakpi River of Chindwin basin in Manipur, India. The new species is distinguished by the following combination of characters: a prominent hexagon-shaped unilobed proboscis with five large-sized conical tubercles on anterior margin, and three or four medium-sized conical tubercles on anteroventral region; transverse lobe with 1335 small- to medium-sized conical tubercles; lateral surface of snout swollen with 818 small- to medium-sized conical tubercles; 3132 lateral-line scales including three pored scales on caudal fin; and a large arch-shaped black spot on each side of opercle, immediately anterior to upper angle of gill opening. The taxonomic status of several species of Garra from Arunachal Pradesh and Mizoram, is reviewed and accordingly Garra minimus is considered as a junior synonym of G. quadratirostris; G. nigricauda as a junior synonym of G. arunachalensis; G. alticaputus and G. kimini as junior synonyms of G. birostris; and G. tyao as a junior synonym of G. rakhinica.

A new striped species of Brachychalcinus (Ostariophysi: Characiformes) from Amapá and Pará states, northern Brazil

Abstract A new species of Brachychalcinus is described from the rio Mapaoni, rio Jari basin, and the coastal rio Araguari, Amapá and Pará states, Brazil. The new species is distinguished from all congeners, except B. reisi, by possessing conspicuous longitudinal dark stripes across the body. It can be diagnosed from B. reisi by having longer predorsal and preanal spines, by having scales with few curved radii, and by having more scale rows between lateral line and midventral scale series. A single specimen from rio Tapajós (Pará, Brazil) bears all the diagnostic features of the new species and is herein tentatively identified as belonging to this taxon, extending its distribution to this river basin.

Morphological description of spontaneous pelvic fin loss in a neotropical cichlid fish.

Pelvic finsare a characteristic structure of the vertebrate Bauplan. Yet, pelvic fin loss has occurred repeatedly across a wide diversity of other lineages of tetrapods and at least 48 times in teleost fishes. This pelvic finless condition is often associated with other morphological features such as body elongation, loss of additional structures, and bilateral asymmetry. However, despite the remarkable diversity in the several thousand cichlid fish species, none of them are characterized by the complete absence of pelvic fins. Here, we examined the musculoskeletal structure and associated bilateral asymmetry in Midas cichlids (Amphilophus cf. citrinellus) that lost their pelvic fins spontaneously in the laboratory. Due to this apparent mutational loss of the pelvic girdle and fins, the external and internal anatomy are described in a series of "normal" Midas individuals and their pelvic finless sibling tankmates. First, other traits associated with teleost pelvic fin loss, the genetic basis of pelvic fin loss, and the potential for pleiotropic effects of these genes on other traits in teleosts were all reviewed. Using these traits as a guide, we investigated whether other morphological differences were associated with the pelvic girdle/fin loss. The mean values of the masses of muscle of the pectoral fin, fin ray numbers in the unpaired fins, and oral jaw tooth numbers did not differ between the two pelvic fin morphotypes. However, significant differences in meristic values of the paired traits assessed were observed for the same side of the body between morphotypes. Notably, bilateral asymmetry was found exclusively for the posterior lateral line scales. Finally, we found limited evidence of pleiotropic effects, such as lateral line scale numbers and fluctuating asymmetry between the Midas pelvic fin morphotypes. The fast and relatively isolated changes in the Midas cichlids suggest minor but interesting pleiotropic effects could accompany loss of cichlid pelvic fins.

Fluctuating asymmetry patterns of common carp (Cyprinus carpio) in fish hatchery center of Kabat, Banyuwangi, Indonesia

A decrease in common carp (Cyprinus carpio) fry quality has occurred in many hatcheries indicated by fry abnormality increase, which causes low survival and growth rates. This research aims to obtain quantitative information of asymmetry level on common carp fry in the Fish Hatchery Centre (FHC) of Kabat as a reference for the breeding program. A total of 200 common carp fries with a total length of 5-7 cm were obtained from FHC of Kabat. The observed magnitude (FAm) and number (FAn) are fluctuating asymmetry. To calculate both of them; bilateral meristic characteristics were measured are pectoral fins radii, ventral fins radii, and scales on the lineal lateralis number. We found that there was an incidence of asymmetric fluctuations in FHC of Kabat with the highest FAm and FAn were obtained in lateral line scales. This implies inbreeding which causes a decrease in hatchery productivity, so the introduction of brood stock from other areas is required.

Malakichthys formosus, a new species of small seabass (Acropomatiformes: Malakichthyidae) from southwestern Taiwan.

A new species of Malakichthys is described based on six specimens collected from deepwaters off southwestern Taiwan, northwestern Pacific Ocean. The new species, M. formosus sp. nov., exhibits distinct morphological characters, primarily characterized by the absence of chin spines, distinguishing it from other congeners with the exception of M. levis and M. mochizuki. It differs from the two species by having more lateral-line scales, a shorter distance between the snout and dorsal-fin origin, a shallower head, fewer scale rows below the lateral line, and the structure of the first anal-fin pterygiophore. Eight species are now recognized in Malakichthys.

A new species of the genus Enneapterygius (Perciformes: Tripterygiidae) from Japan and the Philippines, with a synopsis and synonymy of related species.

A new species of triplefin (Tripterygiidae), Enneapterygius olivaceus n. sp., is described on the basis of 28 type specimens (13.725.1 mm standard length: SL) from Japan (Ryukyu Islands) and the Philippines. The new species is characterized by having 1822 (20) notched lateral-line scales, 2 or 3 (2) scales below the 1st notched lateral-line scale, a single symphyseal mandibular-pore (mandibular pore formula 3 + 1 + 3), black pectoral fins in nuptial males, and no distinct line on the anal-fin membranes. In this study, Enneapterygius minutus (Gnther, 1877), previously regarded as a junior synonym of Enneapterygius philippinus (Peters, 1868), is considered a valid species, being redescribed based on 109 specimens, including the re-examined type specimens. Diagnostic characters and distributional records of the species closely related to E. olivaceus n. sp. are reviewed. Enneapterygius tusitalae Jordan & Seale, 1906, Enneapterygius pardochir Jordan & Seale, 1906 and Enneapterygius punctulatus Herre, 1935 are regarded here as junior synonyms of E. minutus; Tripterygium callionymi Weber, 1909 and Enneapterygius waigiensis Herre, 1935 are junior synonyms of Enneapterygius tutuilae Jordan & Seale, 1906; Enneapterygius cerasinus Jordan & Seale, 1906 is a junior synonym of Enneapterygius unimaculatus Fricke, 1994; Enneapterygius fuligicauda Fowler, 1946 is a senior synonym of Enneapterygius similis Fricke, 1997.

Cabdio occidentalis, a new species from Lake Mashkid basin and the Makran region (Teleostei: Danionidae).

Cabdio occidentalis, new species, is described from the Lake Mashkid basin and the Makran region of Iran. It is distinguished from other species of the genus by a combination of characters: 3842+12 total lateral-line scales, 1923 predorsal scales, 911 pectoral-fin rays, and the absence of a keel between the pelvic-fin base and the genital papilla. The cytochrome c oxidase subunit I (COI) sequence separates C. occidentalis from C. morar, its closest congener, by a p-distance of 5.5%.

Badis limaakumi, a new species of badid fish from Nagaland, Northeast India (Teleostei: Percomorpha: Badidae).

Badis limaakumi, a new species of Badis from Nagaland, Northeast India is distinguished from all its congeners by the following combination of characters: a large (>60 mm SL) and slender body (23.228.0% of SL), presence of an opercular blotch at the base of the opercular spine, absence of blotches on the sides and fins, as well as on the cleithrum, and greater number of lateral-line scales.

Incipient speciation in allopatric Etheostoma rupestre (Percidae: Etheostomatinae) lineages, with the description of three new subspecies.

In recent years, new species descriptions for the North American darters have proliferated. Most species concepts accepted by contemporary ichthyologists require that a valid species be both monophyletic and diagnoseable, yet many lineages exhibit modal or range differences in morphological characteristics without individuals being diagnosable. Such scenarios present difficulties with regards to proper taxonomic recognition of divergent lineages and often prohibit appropriate conservation action. Following the example of recent authors, we provide meristic, geometric morphometric, and pigmentation data to support the recognition of three subspecies of Etheostoma rupestre, a species endemic to the Mobile Basin. These morphological data cohere with previous genetic work for E. rupestre. The nominate subspecies Etheostoma rupetsre rupestre (Tsais Rock Darter) is endemic to the Tombigbee River and Black Warrior River watersheds in Alabama and Mississippi and is characterized by having lower numbers of lateral blotches, lower range and mean of lateral line scales, lower modal number of scales above the lateral line, and lower degrees of nape squamation than other subspecies. Etheostoma rupestre piersoni (Shamrock Darter), ssp. nov., is endemic to the Cahaba and Alabama River Watersheds in Alabama and is characterized by intermediate counts of lateral blotches and higher scale counts and nape squamation than E. r. rupestre. Etheostoma rupestre uphapeense (Jade Darter), ssp. nov., is restricted to several small, disjunct populations in the Coosa and Tallapoosa watersheds in Alabama, Georgia, and Tennessee. Etheostoma r. uphapeense is characterized by having a higher mean number of lateral blotches than both other subspecies and higher scale counts than E. r. rupestre. While E. r. rupestre and E. r. piersoni are widespread and abundant within their respective ranges, E. r. uphapeense has a disjunct range and is often uncommon where it occurs. Etheostoma r. uphapeense should be monitored where it occurs to discern population trends.

Characterizing the Dark Mahseer, Naziritor chelynoides (McClelland, 1839): A Morphological, Osteological, and Molecular Approach

Dark mahseer, Naziritor chelynoides is a vulnerable stream fish in several Asian countries, and developing an effective conservation strategy is impeded by incomplete information about its taxonomy. To address this research gap, in the current study dark mahseer collected from Himalayan stream in India (29°21`99.5` N and 79°33`23.9` E) were examined for their morphometric, meristic, osteological, and molecular characteristics. This study discovered unique features of dark mahseer, including its thin non-hypertrophied lower lip without median lobe, complete post-labial groove, 33 to 34 central perforated lateral line scales, a dark elliptical blotch at the angle of the operculum, and numerous fine black dots on a crescent pattern on scales. This species has 9 to 11 slender gill rakers (595.93±148.71 μm in length), 40 to 41 total vertebrae, 38 to 39 neural spines, 14 to 15 hemal spines, and fused first to fourth abdominal vertebrae. Molecular analysis of cytochrome c oxidase subunit 1 gene (cox1), cytochrome b (cytb), and ATPase subunit 6&8 (ATPase 6&8) genes revealed the genetic distance of 0.08 to 0.10, 0.12 to 0.13, and 0.01 to 0.11 respectively from other Tor species. Our study enhances knowledge of dark mahseer's taxonomy, supporting conservation strategies for this valuable fish species.

A new cavefish of Sinocyclocheilus (Teleostei: Cypriniformes: Cyprinidae) from the Nanpanjiang River in Guizhou, China.

A new species, Sinocyclocheilus xingyiensis, is described based on specimens collected from a karst cave in Guizhou Province, China. The authors used an integrated taxonomic approach, including morphological and molecular data, to identify the new species as a member of the Sinocyclocheilu angularis group, and it can be distinguished from all other members of this group by a combination of the following features: two pairs of long barbels and long pectoral fins, 42-46 lateral-line scales, 7 (13-14) on outer (inner) side of the first gill arch and 35 (14-15 + 4 + 16 - 17) vertebrae. Phylogenetic analyses based on the cytochrome b (cyt b) gene fragment suggest that S. xingyiensis is a sister lineage to Sinocyclocheilus flexuosdorsalis. The genetic distance (Kimura 2-parameter) between the S. xingyiensis and S. angularis groups of Sinocyclocheilus species based on cyt b gene fragment ranged from 1.2% to 15.4%.

Patterns of Phenetic Diversity and Taxonomy of the Ide <i>Leuciscus idus</i> (Cypriniformes, Cyprinidae) from Water Bodies of Russia and Adjacent Countries

Using the methods of population morphology, we studied the structure of phenetic diversity of the ide Leuciscus idus (L.) from the water bodies of the Russian Federation and some neighboring countries. We analysed our own collection and literature data on meristic characters of external morphology, axial skeleton, as well as the pharyngeal teeth formula. The main features contributing to population differentiation were the number of lateral line scales, total vertebrae count, caudal and pre-caudal vertebrae ratio. It was shown that the strong positive relationships of the first two features with the geographical latitude of fish habitats is associated, first of all, not with the direct influence of physical factors functionally dependent on latitude, but with particular (sub)speciation processes in river basins and dispersal of evolutionarily derived forms to the north. The results obtained are discussed in terms of evolutionary trends in the subfamily Leuciscinae and call for a taxonomic revision of the L. idus species in its current volume with elevation of the former subspecies L. idus oxianus to a species rank.