Meristic Research Articles

An integrative taxonomic study on needlefishes (Belonidae) unveils two new species within the genus Ablennes from the Indian Ocean

The needlefish genus Ablennes remains monotypic, characterized by the globally distributed flat needlefish known as Ablennes hians. Their taxonomy has been mired with ambiguities due to the greater-than-average morphological variations observed in samples from different regions. Utilizing integrated taxonomic methods relying on mitochondrial molecular markers, it was revealed that the species initially perceived as a single entity is, in fact, a complex comprising at least three different species. In this context, we introduce two new species: Ablennes joseberchmansis sp. nov. and Ablennes gracalii sp. nov., They are morphologically distinct: in view of the morphometry and meristic characteristics. A. joseberchmansis sp. nov. and A. gracalii sp. nov. display distinct differentiation characteristics from A. hians in terms of dorsal fin, nostril position, dorsal fin origin, vertebrae count, scale counts, head length, eye diameter, interorbital width, maxilla length, dorsal ray height, depth at pelvic origin, lower lobe of the caudal fin, and caudal peduncle depthcaudal peduncle depth. These variations highlight their unique morphological traits and aid in their differentiation within the genus Ablennes. We assessed genetic relationships using a Maximum likelihood (ML) phylogenetic tree, revealing three distinct clades of morphological differences in Ablennes specimens from different morphological groups. The genetic variation, as represented by Kimura 2 parameter (K2P) distances, within the three Ablennes species spans from 6.5% to 9.4%. More specifically, we observed a 7.5% genetic difference between A. hians and A. joseberchmansis sp. nov., and a 6.5% distinction between A. hians and A. gracalii sp. nov. The interspecies divergence between the two newly identified species measured at 9.4%. These findings, which showcase the genetic distinctions among the three morphologically distinct Ablennes specimens, provide strong confirmation for the existence of three separate species within the Ablennes genus of needlefish in the Indian Ocean.

Morphological and genetic data challenge species and subspecies in the Lerista microtis group (Squamata: Scincidae)

The subspecies rank has been widely applied by taxonomists to capture infraspecific variation within the Linnaean classification system. Many subspecies described throughout the 20th century were recognised largely based on perceived variation in single morphological characters yet have since been found not to correspond to separately evolving population lineages, thus requiring synonymy or elevation to full species under lineage-based views of species. These modern lineage-based taxonomic resolutions have resulted from a combination of new molecular genetic techniques, improved geographical sampling of specimens, and more sophisticated analyses of morphological variation (e.g., statistical assessments rather than solely univariate descriptive ones). Here, we revisit the current taxonomic arrangement of species-level and subspecific taxa in the Lerista microtis (Gray) group, which is distributed along a narrow ~2000 km strip on the southern coast of Australia. From specimens of the L. microtis group, an additional species (Lerista arenicola) and two additional subspecies (L. m. intermedia and L. m. schwaneri) were described. We collected data on mensural, meristic, and colour pattern characters to explore morpho-spatial relationships among these taxa. Although our morphological analyses revealed some distinctiveness among specimens from locations assigned to each taxon, this variation is continuous along Australia’s southern coastline, assuming the form of a geographic cline rather than discrete forms. For many characters, however, spatial patterns were inconsistent with the original descriptions, particularly of the subspecies. Moreover, analysis of genome wide restriction-associated DNA loci revealed multiple instances of paraphyly among taxa, with phylogenetic clustering of specimens assigned to distinct species and subspecies. These emerging patterns provide no support for L. arenicola as a species evolving separately from L. microtis. Additionally, our findings challenge the presumed distinctiveness and coherence of the three subspecies of L. microtis. We thus synonymise L. arenicola and the L. microtis subspecies with L. microtis and provide a redescription of a single yet morphologically variable species—an arrangement that best reflects evolutionary history and the continuous nature of morphological variation across space.

A new species of the Cyrtodactylus brevipalmatus group (Squamata: Gekkonidae) from Phuket Island, Thailand with a discussion of the group’s potential biogeography

Model based integrative analyses supports the recognition of a new species of the Cyrtodactylus brevipalmatus group from Phuket Island, Thailand. Cyrtodactylus thalang sp. nov. is most closely related to the sister species C. brevipalmatus from the Thai-Malay Peninsula and C. cf. brevipalmatus from Langkawi Island, Kedah State, Peninsular Malaysia. Based on the mitochondrial gene ND2, C. thalang sp. nov. bears an uncorrected pairwise sequence divergence of 14.7% and 15.1% from C. cf. brevipalmatus and C. brevipalmatus, respectively, significantly different (p<0.05) mean values of meristic and morphometric characters, and discrete categorical morphological differences. A multiple factor analysis morphospatially statistically placed C. thalang sp. nov. well outside all other species of the brevipalmatus group. The BAYAREALIKE model of a BioGeoBEARS analysis indicated the origin of the brevipalmatus group was in western Indochina with subsequent south to north speciation along the Tenasserim Mountains followed by a west to east invasion of northern Thailand, Laos, and northwestern Vietnam northeast of the Chao Phraya Basin and north of the Khorat Plateau.

Prebosphoric occurrence of Korean rockfish, Sebastes schlegelii Hilgendorf, 1880 in southwestern Black Sea with notes on its morphometry and dispersal potential

On 21 December 2023 one specimen of Sebastes schlegelii Hilgendorf, 1880 have been captured by means of a commercial bottom trawler towed at a depth of 30 m off Şile coast. Following its first occurrence in Turkish Black Sea waters off Giresun coast on 6 March 2023, it has recently reported from the Sea of Marmara (Gulf of İzmit) on 7 January 2024, exhibiting a noteworthy dispersal speed which required less than one year to migrate across nearly a 1,000 km. Therefore, the dispersal and potential interactions with indigenous species of this invasive teleostean along theTurkish coast should be monitored carefully. In the present article, authors provide full morphometric and meristic characters of S. schlegelii, as well.

First case of a reversed Parabothus taiwanensis Amaoka & Shen, 1993 from Taiwan (Pleuronectiformes: Bothidae), with first evidence of situs inversus viscerum in bothid.

Reversed condition is rarely found in most flatfishes in natural environment, except for some certain species. The mechanism controlling the reversals in flatfishes has been studied in some cultivated species, whereas some have only few cases for the entire family and remain unclear. Here, we report the first record of a dextral (reversed) specimen of Parabothus taiwanensis Amaoka & Shen, 1993 collected off southwestern Taiwan recently. It represents the second reversed case ever recorded in Bothidae. We aim to provide a detailed description of this dextral specimen and compared to the sinistral (normal) specimens collected from the vicinity. Specimens were fixed in 4% formaldehyde and transferred to 70% ethanol for preservation. Meristic and morphometric characters were examined for both dextral and sinistral specimens. Dissections were made on specimens to confirm the position of internal organs. Lastly, X-radiographs were taken to elucidate the osteological features. As a result, no differences of both meristic and morphometric characters were observed between the dextral and sinistral specimens. Nevertheless, situs inversus viscerum is discovered in the dextral specimen for the first time in Bothidae and the sixth record within flatfishes.

Morphological features of round whitefish Prosopium cylindraceum lake Lama (Putorana Plateau)

The article presents materials on the meristic and plastic characteristics of the round whitefish, Prosopium cylindraceum (Pennant, 1784), in Lake Lama, which is part of the Norilo-Pyasinsky water ecosystem and the Pyasina River basin. The Yenisei and Pyasina rivers define the western boundary of this species’ habitat. While the round whitefish is a relatively rare species with a low population in the Yenisei basin, it is abundant in the Pyasina basin, especially in some of the upper water bodies. The round whitefish is a common species in the Norilo-Pyasinsky lakes and is present in all large lakes of the region, except for lake Keta, where it has not been found. Both river and lake-river forms of the round whitefish are present in these water bodies. Both forms have experienced a significant impact from non-commercial fishing, and in some parts of the basin, they have practically disappeared or significantly reduced in number. The areal of the round whitefish in the Pyasina River basin also extends to some right-hand tributaries (Dudypta, Samoyedskaya, etc.) in the northern regions of the basin. The tributaries where the round whitefish is found are typically characterized as rocky, fastflowing streams. The variability of meristic characters of the round whitefish in lake Lama, lake Sobachye, and some parts of the upper Pyasina river are examined. Current data show the round whitefish in the Pyasina River basin and other water bodies of the Taimyr region is represented by a relatively homogeneous population with close values in such basic parameters as lateral line, the number of gill rakers, and other characteristics.

Biometric Analysis of Fish Remains from Palaeolake Boltysh (Ukraine)

The results of the study of the meristic and morphometric characters of complete and fragmentary skeletons of Notogoneus gracilis (Gonorynchidae) and Boltyshia brevicauda (Umbridae) recovered from Paleocene–Eocene lacustrine deposits of the Boltysh impact structure are presented in the paper. Some of the specimens previously assigned to Thaumaturus avitus were reidentified as Boltyshia brevicauda. The meristic characters of the specimens considered are stable in both species and refer to those in the respective type series. A previously unknown caudal fin formula (I 6–6 I) is observed in several specimens of Boltyshia brevicauda. The latter species is characterised by more variable meristic characters compared to Notogoneus gracilis.

Study of some morphometric and meristic characteristics of Alepes vari (Cuvier, 1833) collected from the Arabian coast.

The present study examines the correlations between fifteen morphometric and ten meristic characters and total length (TL) of males, females, and combined sexes of Alepes vari (Cuvier, 1833) collected from Karachi fish harbor, West Wharf of Karachi Coast. Statistical analyses of linear regression relationships show mostly strong correlations (r≥0.70; p<0.05) between total length (TL) and most morphometric characters in males, females, and combined sexes, except the height of pectoral-fin (PFH), and pelvic-fin base length (PelFL); whereas, meristic characters were found to be constant and indicate weak or negative type correlations (r≤0.50; p>0.05) with total length (TL). Hence, according to our present results, there is a direct relationship between the total length of fish and all morphometric characters, which were found to be the best indicators of positive allometric pattern growth in fish. Moreover, analysis of the 2-sample t-test revealed (t-test; p>0.05) that no sexual dimorphism was reported in Alepes vari. Thus, our present study could be valuable in systematic classification, sexual dimorphism, and management of this species on the Karachi coast.

Morphological and molecular evidences confirm a new species in Ophichthus (Anguilliformes: Ophichthidae) from the east coast of India

A new species of snake eel, Ophichthus suryai sp. nov., is discovered based on six specimens collected from three different estuarine ecosystems in Odisha, India. The new species can be distinguished from its closely allied congeners Ophichthus alleni, Ophichthus zophistius, and Ophichthus altipennis, and other members in this genus by having the dorsal fin origin (DFO) just above or slightly anterior to the gill opening, its unique vertebral count (7-8/45-47/142-142), and teeth patterns consisting of multiple rows on both maxilla and mandible. The distinctiveness of this new species is also supported at the molecular level by a strongly supported (bootstrap value &gt;99%) monophyletic grouping of the mitochondrial DNA (mtDNA) Cytochrome Oxidase I (COI) gene sequences of the holotype and one paratype. The current study describes the morphometric and meristic characters and molecular phylogeny of Ophichthus suryai sp. nov.

A new species of Inpaichthys from the rio Canamã, rio Aripuanã basin, Mato Grosso State, Brazil, with a redefinition of the genus (Characidae: Stethaprioninae)

Abstract A new species of Inpaichthys is described from a tributary of the rio Canamã, rio Aripuanã basin, Mato Grosso State, Brazil. The new species can be diagnosed from its congeners by the color pattern in life and by morphometric and meristic features. A comprehensive phylogenetic analysis of the Characidae, conducted to assess the generic placement of the new species, revealed that Hasemania nambiquara is also a member of Inpaichthys and thus transferred to this genus. A monophyletic group composed of the three known species of Inpaichthys is hypothesized to be related to Nematobrycon and a clade composed of Carlana, Pseudochalceus, and Rhoadsia, among the taxa herein analyzed. A diagnosis for Inpaichthys and morphometric and meristic data of I. kerri are also presented.

Comparative analysis of Oreochromis niloticus and a putative hybrid (Wesafu): A Search for morphometric identity

Oreochromis nilotics is an important aquaculture species worldwide. Members of the tilapiine family hybridize easily in nature. The present study was conducted to examine the morphometric and meristic characteristics of Oreochromis niloticus from New Calabar River and a putative hybrid called Wesafu found in Epe Laggon. The study was based on the hypothesis that the tilapia hybrid will possess traits which will be intermediate to those of O. niloticus. A total of 24 morphometric measurements and 8 meristic counts were used to generate data which were analyzed using t-test. The total length of Wesafu and O. niloticus fish ranged from 7.00 -24.5cm and 12.00 -15.5cm respectively. Our study rejected the hypothesis of mid-values Additionally, the total length and body weight relationship were found to be a straight line in logarithmic scale expressed Log BW = 2.7724 Log TL - 1.6171 and Log BW = 2.8442 Log TL - 1.7114 for both Wesafu and O. niloticus respectively. The value of regression co-efficient "b" obtained for the length-weight relationship of Wesafu and O. niloticus was 2.7 and 2.8 respectively.

Genetic and morphological evidence of a single species of bronze featherback (Notopterus notopterus) in Sundaland

The bronze featherback (Notopterus notopterus) is an iconic species of freshwater fish commonly found in South-East Asia and of great commercial and patrimonial importance. At present, the genus Notopterus comprises of two distinct species, Notopterus notopterus (Pallas, 1769) and Notopterus synurus (Bloch & Schneider 1801). On the Indonesian archipelago, genetic diversity and morphology of the bronze featherback were investigated for conservation purposes. The use of DNA-based species delimitation methods, applied to 165 Cytochrome oxidase I sequences of Notopteridae (121 belonging to N. notopterus), evidence a concordance between species and Molecular Operational Taxonomic Unit (MOTU) and the two species of Notopterus are recognized. In N. notopterus, 9 haplotypes are detected among the 121 sequences analyzed, and three are restricted to Sundaland. These three haplotypes had distinct geographic distribution with a haplotype observed in Java, Sumatra and Borneo, another haplotype restricted to South Sumatra and a third haplotype only found in Northern Sumatra. The analyze of 21 morphometric and 9 meristic variables revealed two groups within N. notopterus, which were only supported by subtle differences in measurements with overlapping distributions between groups. The present study supports the validity of Notopterus notopterus in Sundaland and the remarkable genetic continuity among populations across its range distribution.

Additional Record of Rare Pilot Fish, Naucrates ductor (Linnaeus, 1758) with Some Biological Notes from the Northern Aegean Sea, Türkiye

In this study, four individuals of pilot fish Naucrates ductor which were accidentally caught by a commercial purse seiner in Edremit Bay (Aegean Sea) were investigated. The morphometric and meristic characteristics, sex, maturity stages, otoliths, age and stomach contents of the specimens were evaluated. This study contributes to the existing literature by providing additional records from specimens reported from the northernmost location reported so far as well as other biological information for the rarely observed pilotfish.

Ontogeny of vertebral column and fin development, and detection of deformations in hatchery-reared European Flounder (Platichthys flesus) during early life stage

Understanding the skeletal development and deformations for aquaculture candidate fish species is vital for successful aquaculture practices. Developmental abnormalities at early life stages may reduce fish viability, growth, and wellbeing. This study was carried out to investigate the skeletal ontogeny and skeletal deformities of the European flounder (Platichthys flesus) at early life stage. Artificially produced European flounder larvae (n = 270) were randomly selected at a regular interval (30 fish at each sampling) from hatching to 50 days post-hatch (dph) and their skeletal ontogeny and skeletal deformations were evaluated by using bone and cartilage staining techniques. The average length of fish was 2.71 ± 0.04 mm at 0 dph and reached 19.76 ± 1.7 mm at 50 dph. The notochord began to form at 10 dph and finished flexion at 30 dph. Hypural rays appeared between 10 and 15 dph, followed by appearance of tail fin rays. Urostyle developed at 30 dph and began to ossify at 40 dph. Meristic characters showed an interspecific variation. At least one type of deformation was observed on 23.3% of larvae, and a total of 13 different deformations were identified. The most common deformation was the deformed vertebra which was observed 13 times followed by deformed dorsal fin ray, deformed caudal fin ray, and deformed neural arch and/or spine. Skeletal development during the early life stage of European flounder under culture conditions could be useful for future culture attempts and for early detection of skeletal deformations.

Morphological and genetic characteristics of garfish Belone belone (L., 1760) (Belonidae, Teleostei) population from the southern Bulgarian Black Sea coast

This study was conducted to investigate genetic and some morphometric and meristic characteristics of garfish Belone belone from Nesebar in the Bulgarian Black Sea coast. Twelve morphometric characters were measured, and six meristic characters were counted for each individual. Based on both sexes’ morphological and meristic analyses, no statistically significant sexual differences were observed. Additionally, DNA barcoding was done. The fragment of the cytochrome oxidase subunit I (COI) gene of mitochondrial DNA was sequenced to supplement the species identification and population diversity study. Two haplotypes were found out of 39 sequences, indicating a low level of haplotype diversity (0.146±0.072). Nucleotide diversity was also found to be low (0.00023±0.00011). The Nesebar population of B. belone requires conservation efforts, due to the highly decreased mtDNA genetic diversity.

Biometrijske osobine rumenca okana, Pagellus bogaraveo (Brunnich, 1769) (Osteichthyes: Sparidae) u istočnom dijelu Jadrana

A biometric analysis was performed on a sample of 420 specimens of the blackspot seabream, Pagellus bogaraveo (Brunnich, 1769), from the eastern Adriatic Sea. The total length of all specimens ranged from 9.2 to 47.8 cm (23.70 ± 7.63 cm). Eighteen morphometric and eight meristic characteristics were determined. There were no statistically significant differences between the sexes in the morphometric and meristic characteristics of the blackspot seabream in the Adriatic Sea. Regarding meristic characteristics, there are no significant morphological differences between the blackspot seabream population in the Adriatic Sea and that in other areas of the Mediterranean Sea and the eastern Atlantic Ocean. Relative growth was studied by comparing changes in morphological characteristics with growth in total length and head length. The results indicate the presence of a single population of P. bogaraveo in the Adriatic Sea.

Length-weight relationship and morphometric and meristic variation in Dinnawah snowtrout, Schizothorax progastus, inhabiting the Suru River and its tributaries of Kargil, Ladakh Region

Abstract Morphometric variations across fish stocks have long been acknowledged as useful for determining population structure and identifying stocks. Schizothorax progastus (McClelland) is a common, dominant fish in most cold-water rivers and is considered a good sport fish and also delicious in taste. For the people of Ladakh, this fish is a significant source of nutrition. A total of 70 specimens were collected for this study. A total of 24 morphometric and six meristic characters were studied, with 18 morphometric characters assessed as percentages of total length and four characters analyzed as percentages of head length. Standard length and fork length had the strongest correlations with total length at 0.98 and 0.99, respectively. Overall, the findings demonstrated that all morphometric features had linear correlations and exhibited a high degree of association (P &lt; 0.05). The meristic counts examined in this study were consistent among all fish of various sizes, suggesting that body size had no effect on them. The biological information generated from this study serves as an essential guideline for future management and conservation of S. progastus, an important food source in the Ladakh, Trans Himalayan region.

IDENTIFIKASI MORFOMETRIK DAN MERSITIK BETTA BURDIGALA ASAL PERAIRAN BANGKA SELATAN SEBAGAI DASAR PENGEMBANGAN AKUAKULTUR

Betta burdigala is a type of endemic fish from Bangka Island. The Betta burdigala on Bangka Island is threatened with extinction, with Critically Endangered (CR) status. The decline in the Betta burdigala fish population is caused by habitat degradation and environmental damage. The existence of Betta burdigala fish has never been reported in waters other than Bangka Island. This research aimed to described the morphometric and meristic characteristics of Betta burdigala fish from South Bangka waters as a basis for the conservation and development of aquaculture. The method used in this research is observation, with direct measurement, and observation of morphometric and meristic characters as well as literature studies to identify the morphology of Burdigala betta. The results of this research showed that the morphological characters of Betta burdigala have a mixed form. The shape of the tail fin of the Betta burdigala is round (spherical).. This type of fish's mouth is terminal (located in the anterior middle of the head). The type of scales it has is cosmoid shaped. The average morphometric characters measured were TL(28.25mm), SL(22.05mm), HL(6.15mm), ED(1.5mm), IW(1.6mm), BD(3.8mm), PDL(1.3mm), DBL(7.6mm), DFH(5.8mm), PAL(9.2mm), ABL(10.85), CPD(3.25mm), LUCL(5mm), LMCL(4 .5mm), LCLL(4.1mm). The average meristic character of the Betta burdigala fish is that the dorsal fin rays have the formula D.XIV, the anal fin rays have the formula A.XXV. The caudal fin radius has the formula C.XIII.

Morphology and cytochrome b gene identification of Cempedik fish for ascertainment of domestication broodstock source in Belitung Island

Cempedik, a native fish of Belitung Island, has economic potential due to its dependence on natural supplies in local rivers. Domestication efforts are needed for this species to continue its availability and protect the sustainibility of its natural population. However, there is little information regarding this freshwater fish belonging to Osteochilus spilurus and the emergence of phenotypic variations in fish with the same local name from different rivers. This study identified morphology and cytochrome b genes from Cempedik fish obtained from Gantung, East Belitung and Membalong, West Belitung. The fin membranes of fish from West Belitung are reddish in color, while the color is brownish gray in fish from East Belitung. Meristic variation is found in scales on lateral line. Fish from both locations were in different clusters in the phylogenetic tree construction with large genetic distances. It is possible that there are cryptic conditions or species differences in the two fish samples.

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.