Using otolith shape and morphometry to identify four Alburnus species (A. chalcoides,A. escherichii,A. mossulensis and A. tarichi) in Turkish inland waters

Asteriscus otolith shapes as well as their morphometry and shape contours were investigated in order to identify four allopatric Alburnus species: A. chalcoides (Güldenstädt, 1772) (Ordu), A. escherichii Steindachner, 1897 (Eski?ehir), A. mossulensis Heckel, 1843 (Tunceli), and A. tarichi (Güldenstädt, 1814) (Van) in Turkish inland waters. These were compared using the shape indices (form factor, roundness, circularity, ellipticity, rectangularity and aspect ratio), and the morphological characters [otolith weight (OWE), otolith length (OL), otolith width (OW), otolith perimeter (OP), and otolith area (OA)]. The overall canonical discriminant analysis (CDA) classification score was 93.8%, with the lowest score for A. escherichii (82.5%) and the highest for A. chalcoides (100%). The otolith shapes, morphology and shape contours of all sampled fish were a clear species differentiator, thereby demonstrating that the otolith shape is species‐specific. The current study presents for the first time comprehensive variation information on interspecific left‐right asteriscus otoliths in males and females of each Alburnus species: A. chalcoides from Ordu, A. escherichii from Eski?ehir, A. mossulensis from Tunceli and A. tarichi from Van, based on a total of 307 individuals. Scanning electron microscopy (SEM) images, shape contours and other otolith characters vary within the same genus; these differences should be investigated not only in other freshwater fish species or genera but also in the same species living in different habitats. In addition, further investigation is required not only with respect to the morphometry, biometry, shape, geometry, and shape contours of the otoliths, but also regarding the genetic methods for robust identification of various sympatric and allopatric fish populations.     

Comparative morphology of the sagittal otolith in three species of south Caspian gobies

Sagittal otolith shapes were investigated in order to identify three sympatric species of south Caspian gobies (Caspian goby Neogobius caspius, deepwater goby Ponticola bathybius and bighead goby Ponticola gorlap). The sagittal otoliths in P. bathybius have a rectangular shape and are thick, whereas in N. caspius they are relatively round and thin. In P. gorlap, otoliths have an elongated shape and are relatively thick. The noticeable difference among the otoliths of the three species is the presence of one anterior and one posterior projection in the otoliths of N. caspius and P. gorlap. Among shape indices, form factor (irregularity of surface area), circularity, aspect ratio and rectangularity are the foremost that indicate interspecific variability. The canonical discriminant analysis correctly classifies 94·7% of the original group cases. The overall analyses show the relevance of applying otolith shape for interspecific distinction of the three species of Caspian gobies.     

Ageing Belanger's croaker,Johnius belangerii (Cuvier, 1830), based on otolith shape analysis

The use of morphological characters and otolith weight as predictors of fish age has proven to be an efficient, objective and precise method, but studies were heretofore focused primarily on fast‐growing fish species. In the present study, Belanger's croaker, Johnius belangerii (Cuvier, 1830), is presented as a model species for slow‐growing fish where it is hypothesized that age has a significant effect on the otolith shape, and that the otolith weight has the potential to predict individual fish age as an alternative and objective method. Discriminant function analysis (DFA) of shape variables and cross‐validation were applied to a total of 359 sagittal otoliths in the age groups 0, 1 and 2. The shape variables demonstrated 64.1% correct age classification, and a 93.5% correct age classification with the inclusion of otolith weight in the discriminant function. Results show that a combination of shape variables and otolith weight work well in age determination of Belanger's croaker, and demonstrate its application potential for sciaenids that are distributed throughout the coastal waters of China.     

Otolith patterns of rockfishes from the northeastern pacific

Sagitta otolith shape was analysed in twenty sympatric rockfishes off the southern California coast (Northeastern Pacific). The variation in shape was quantified using canonical variate analysis based on fifth wavelet function decomposition of otolith contour. We selected wavelets because this representation allow the identifications of zones or single morphological points along the contour. The entire otoliths along with four subsections (anterior, ventral, posterodorsal, and anterodorsal) with morphological meaning were examined. Multivariate analyses (MANOVA) showed significant differences in the contours of whole otolith morphology and corresponding subsection among rockfishes. Four patterns were found: fusiform, oblong, and two types of elliptic. A redundancy analysis indicated that anterior and anterodorsal subsections contribute most to define the entire otolith shape. Complementarily, the eco‐morphological study indicated that the depth distribution and strategies for capture prey were correlated to otolith shape, especially with the anterodorsal zone. J. Morphol. 276:458–469, 2015. © 2014 Wiley Periodicals, Inc.     

The use of otolith shape analysis for ageing juvenile red snapper, Lutjanus campechanus

Morphological changes in otolith shape with age, of young (<age 3) red snapper were examined through shape analysis and tested as an objective method for age determination. Otoliths from two collections of juvenile fish (hatchery and wild) were used in the study. First, shape analysis was applied to a series of known-age otoliths from hatchery-reared age 0, 1 and 2 fish. Multidimensional scaling and non-parametric analysis of similarities showed significant shape differences among the three age classes of fish. Discriminant function analysis and cross-validation classification showed 65.6% correct age classification based on shape variables alone, and 86.7% correct age classification with inclusion of otolith weight in the discriminant function (n?=?90). Subsequently, the method was applied to otoliths from a series of age 0, 1 and 2 wild caught red snapper. Otoliths from wild fish showed a similar age classification success rate of 68.9% based on shape variables alone and 86.7% correct age classification with the inclusion of otolith weight in the discriminant function (n?=?90). Ageing of juvenile red snapper through otolith increment counts has been difficult in past studies and this study provides an alternative, objective method of otolith shape analysis for ageing young fish of this species.     

Shape indices to identify regional differences in otolith morphology of comber, Serranus cabrilla (L., 1758)

Sagittal otoliths from the Atlantic and Mediterranean regions of Serranus cabrilla L. were compared using shape indices (form‐factor, roundness, circularity, rectangularity, ellipticity and eccentricity). Regional differences were best described by form‐factor, circularity and eccentricity variables. The canonical discriminant functions were built with form‐factor or rectangularity indices. The results indicated slight regional variations. The G‐test was the criterion more useful to identify the otolith origin in the discriminant analysis.     

Otoliths as natural tags in the systematics of salmonids

Synopsis We studied otolith shape in two species of Salmo and two species of Salvelinus to quantify the accuracy of intraspecific, interspecific, and intergeneric identification. Otolith shape is chiefly population and species specific. Between genera, only 3% of the specimens were incorrectly grouped using discriminant analysis.     

The concept of genus within the family Phytoseiidae (Acari: Parasitiformes): historical review and phylogenetic analyses of the genus Neoseiulus Hughes

Systematic studies on the family Phytoseiidae were first conducted at the beginning of the 20^th century but increased greatly after the Second World War. Various classifications have been proposed based on different characters such as: dorsal, ventral, and leg chaetotaxy; the shape of ventrianal and sternal shields; the shape of the insemination apparatus (spermatheca) and spermatodactylus; the number of teeth on the movable digit of chelicera; and dorsal and ventral adenotaxy. The genus concepts developed over the last five decades can be divided into two main categories or hypotheses. The first, supported mainly by Chant and McMurtry, focuses on dorsal and ventral chaetotaxy, and the genera so defined usually include a great number of species. The second category, proposed by Athias‐Henriot, considers the shape of the insemination apparatus as the key character, and the genera so defined usually include a limited number of species. From a diagnostic point of view, both classifications have a valid structure, but the question investigated herein was: which of the two classifications or hypotheses fits phylogenetic evolution? To answer this, we conducted molecular phylogenetic analyses (using the genes ITS and 12S rRNA) on the genus Neoseiulus, which has been subjected to classification based on the two main genus concepts. The results showed that the first hypothesis (Chant and McMurtry) leads to polyphyly of the genus Neoseiulus, while the second (Athias‐Henriot) leads to paraphyly of the genus. The results show that acarologists who first decided that the insemination apparatus was of evolutive importance could be correct as the shape of the insemination apparatus seems to better fit evolutive clades than dorsal and ventral chaetotaxy. The morphology of this organ, however, must be more accurately studied to better define homologies. The present paper investigates the two main hypotheses proposed until now for classification of Phytoseiidae and thereby opens the way for improved classification. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 253–273.     

A new species of Pomatoschistus (Teleostei,Gobiidae): the Mediterranean's smallest marine fish

The new sand goby species Pomatoschistus nanus (Teleostei: Gobiidae) is described from the northern coast of the Levantine Sea (eastern Mediterranean Sea) based on both morphological and DNA barcoding data. The new species is the smallest fish in the Mediterranean Sea and may be distinguished from congeners by the following features: predorsal area, first dorsal‐fin base and breast naked; δ‐pore missing; anterior point of the suborbital row b not reaching level of posterior point of suborbital row d; slightly emarginated caudal fin and nape coloration pattern. DNA barcode data clearly discriminate Pomatoschistus spp. in the neighbour‐joining tree with an average of 17·7% interspecific K2P distance. The most closely related taxon to P. nanus sp. nov. is Pomatoschistus bathi and the most distantly related is Pomatoschistus tortonesei with 11·9 and 21·9% K2P distances respectively. Morphometric and genetic data are also provided for Pomatoschistus bathi.     

Sex-linked variations in the sagittal otolith biometry of Nemipterus randalli (Russell, 1986) from the eastern Mediterranean Sea

Few studies have been conducted on the sagittal otolith shape and morphometry of Nemipterus randalli, and none of these studies has examined the effect of sexual dimorphism on the otolith morphology of this species, therefore this study aimed to contribute to knowledge about the otolith morphology of N. randalli, an invasive fish species for the Mediterranean Sea. For this purpose, a total of 132 samples (51 female and 81 male) were obtained from İskenderun Bay with the help of commercial fishermen in November 2018. Relationships between otolith measurements and fish size were determined. Shape indices and elliptic Fourier coefficients were calculated. Significant differences were detected between males and females in all analysis. The sexes were separated from each other using both shape indices and elliptic Fourier coefficients. However, shape analysis was more effective in distinguishing sexes than traditional morphometric analysis. Asymmetry in the otolith morphology of sexes has been attributed to differences in the growth and sexual maturity of male and female fish. The results of this study indicated that sexual dimorphism in Nemipterus randalli was also reflected in the otolith morphology.     

Relationships between otolith and fish size from Mediterranean and north‐eastern Atlantic species to be used in predator–prey studies

Regressions between fish length and otolith size are provided for 40 species from the north‐eastern Atlantic Ocean and 142 species from the Mediterranean Sea. Regressions were also estimated at genus level. Most of the regressions (c. 84%) explained a high percentage of the deviance (>75%).     

Morphological divergence and diagnostic characters of ginger goby <Emphasis Type="Italic">Neogobius eurycephalus</Emphasis> (Kessler, 1874) and surman goby <Emphasis Type="Italic">N. cephalargoides</Emphasis> Pinchuk, 1976 (Perciformes,Gobiidae)

Comparative analysis of morphometric characters of surman goby Neogobius cephalargoides and of two subspecies of ginger goby N. eurycephalus is made. Characteristics liable to size variation and sex dimorphism are revealed. Independence of the investigated species and the diagnostic value of characters previously suggested for classification are confirmed. The obtained data confirm isolation of north-western populations of ginger goby as a separate subspecies N. eurycephalus odessicus and suitability of three meristic characters for differentiation of the subspecies: the number of rays in the second dorsal fin and anal fin and the number of transverse rows of scales.     

Integrative insect taxonomy based on morphology,mitochondrial DNA,and hyperspectral reflectance profiling

Integrative taxonomy is considered a reliable taxonomic approach of closely related and cryptic species by integrating different sources of taxonomic data (genetic, ecological, and morphological characters). In order to infer the boundaries of seven species of the evacanthine leafhopper genus Bundera Distant, 1908 (Hemiptera: Cicadellidae), an integrated analysis based on morphology, mitochondrial DNA, and hyperspectral reflectance profiling (37 spectral bands from 411–870 nm) was conducted. Despite their morphological similarities, the genetic distances of the cytochrome c oxidase subunit I (COI) gene among the tested species are relatively large (5.8–17.3%). The species‐specific divergence of five morphologically similar species (Bundera pellucida and Bundera spp. 1–4) was revealed in mitochondrial DNA data and reflectance profiling. A key to identifying males is provided, and their morphological characters are described. Average reflectance profiles from the dorsal side of specimens were classified based on linear discriminant analysis. Cross‐validation of reflectance‐based classification revealed that the seven species could be distinguished with 91.3% classification accuracy. This study verified the feasibility of using hyperspectral imaging data in insect classification, and our work provides a good example of using integrative taxonomy in studies of closely related and cryptic species. © 2015 The Linnean Society of London     

Otolith microchemistry of tropical diadromous fishes: spatial and migratory dynamics

Otolith microchemistry was applied to quantify migratory variation and the proportion of native Caribbean stream fishes that undergo full or partial marine migration. Strontium and barium water chemistry in four Puerto Rico, U.S.A., rivers was clearly related to a salinity gradient; however, variation in water barium, and thus fish otoliths, was also dependent on river basin. Strontium was the most accurate index of longitudinal migration in tropical diadromous fish otoliths. Among the four species examined, bigmouth sleeper Gobiomorus dormitor, mountain mullet Agonostomus monticola, sirajo goby Sicydium spp. and river goby Awaous banana, most individuals were fully amphidromous, but 9–12% were semi‐amphidromous as recruits, having never experienced marine or estuarine conditions in early life stages and showing no evidence of marine elemental signatures in their otolith core. Populations of one species, G. dormitor, may have contained a small contingent of semi‐amphidromous adults, migratory individuals that periodically occupied marine or estuarine habitats (4%); however, adult migratory elemental signatures may have been confounded with those related to diet and physiology. These findings indicate the plasticity of migratory strategies of tropical diadromous fishes, which may be more variable than simple categorization might suggest.