Scanning electron microscopy and morphological analysis reveal size‐dependent changes in the scale surface ornamentation of tooth‐carp <i>Aphaniops hormuzensis</i> (Teleostei; Aphaniidae)

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The scale morphology of a native goby, Awaous jayakari (Gobiidae) was studied using scanning electron microscopy and light microscopy. The morphological descriptions were based on the scale's type, shape, and features of the anterior, posterior, and lateral fields. Further characteristics of the focus, circuli, radii, lepidonts, and cteni, were investigated. Morphometric indices were calculated for some scales. Shape variability of scales was high in different regions. However, the majority of scales displayed a polygonal shape (hexagonal and pentagonal). Both ctenoid and cycloid scales were observed in the studied fishes. The ctenoid scale of A. jayakari was peripheral and characterized by the presence of one row of marginally located spines in two completed and uncompleted subtypes. The focus was positioned posteriorly or postero-centrally. The microscopic examinations revealed the presence of lepidonts of different sizes being very tiny, small, or prominent performing flat, blunt, pointed, short, or truncated shapes. The rostral margin of the scales was convex to moderately flattened and represented striate, scalloped, or waved types. Lateral fields were often flattened in all regions, while convex in the lateral fields of the scales of some individuals. The posterior field showed variations in different regions, for example, tapered and flattened ends. The anterior-posterior axis presented a laterally expanded or an elongated extension. The considerable morphological variation in the scales of various body regions makes it difficult to nominate a typical scale to be used in taxonomic studies. However, the key scales can be used for the comparison of different Awaous species.

Section: Discussionsupporting

confidence: 93%

“…The mean and range of the scale indices are given in Table 1. The Ibáñez Lippitsch, 2010;Teimori, Esmaeili, & Motamedi, 2021;Teimori, Iranmanesh, et al, 2021).…”

Section: Scale Indicesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Morphological and microstructural characteristics of scales in longnose goby Awaous jayakari (Teleostei: Gobiidae): Light and scanning electron microscopy approaches

Jufaili

Masoumi

Esmaeili

et al. 2021

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“…Scales have been used to access sexual dimorphism, age determination, and growth, past environment experienced by fish, discrimination between hatchery‐reared and wild populations, migration, environmental pollution of the water, assessing the genetic structure of the population, and phylogenetic affinities (Chu, 1935; Dapar, Torres, Fabricante, & Demayo, 2012; Das, 1959; Esmaeili, Zarei, Vahed, & Masoudi, 2019; Ferrito, Corsaro, & Tigano, 2003; Jawad, 2005a, 2005b; Lanzing & Higginbotham, 1974; Pacheco‐Almanzar, Loza‐Estrada, & Ibáñez, 2020; Seshappa, 1999). The use of Scanning Electron Microscopy (SEM) has greatly increased the importance of scale morphology in ichthyological studies by providing hidden characteristics (see Esmaeili et al, 2007; Esmaeili, Baghbani, Zareian, & Shahryari, 2009; Esmaeili et al, 2019; Jawad, 2005a, 2005b; Teimori, Esmaeili, & Motamedi, 2021). For example, scale surface morphology and microstructures have previously been used for the identification of the Cichlidae (Lippitsch, 1995), Cyprinidae (Jawad, 2005a, 2005b), Cyprinodontidae/Aphaniidae (Esmaeili et al, 2019; Esmaeili & Gholami, 2007; Ferrito et al, 2003; Ferrito, Pappulardo, Fruciano, & Tigano, 2009; Teimori, Motamedi, & Golmakan, 2017a; Teimori, Motamedi, & Manizadeh, 2017b), Mugilidae (Esmaeili et al, 2014) and Clupeiformes (Purrafee Dizaj, Esmaeili, Teimori, & Abbasi, 2020).…”

Section: Introductionmentioning

confidence: 99%

Hidden morphological and structural characteristics in scales of mullid species (Teleostei: Mullidae) using light and scanning electron digital imaging

Echreshavi

Esmaeili

Teimori

et al. 2021

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The scale morphology of nine Mullidae taxa consisting of three genera and nine species from the Persian Gulf and the Gulf of Oman was described and compared using light and scanning electron microscopy from four different body regions. The general scale type in the studied mullid species was ctenoid except in the head region of Mulloidichthys vanicolensis and Parupeneus margaritatus, which had cycloid scales. The scales demonstrated a large focus with the central or centro‐posterior position. The large variations of scale morphology were observed for the scales from different body regions of a single species. The shape of focus was in five types with the round type being the most common. In the scales of most examined species, there were 5–6 radii present in the anterior field. No radii exist in the lateral and posterior fields, and the radii orientation was parallel in all the studied species. The rostral margin of scales represented five types among the studied species; waved (M. vanicolensis), smooth in (P. rubescens), dentate (Upeneus doriae), scalloped (U. vittatus), and fluted (U. tragula). The lepidont shape varied among the species from blunt to flat, pointed, tiny, sharp, pointed, triangle, short, and long. The results also showed that the relative scale size has a desirable contribution to separate the examined genera. The scale morphological‐based tree was largely consistent with the known systematics of the studied fishes. It was concluded that variation of scale characters has probably taxonomic and even phylogenetic information in both species and genus levels in the studied mullid fishes. However, variation of scale morphology between body regions, as shown in this study, suggests that scale characters should be used cautiously for taxonomic studies of these fishes.

Scale morphology variability in cyprinid fishes and its significance in taxonomy using light and scanning electron microscopy: A case study of the genus Garra Hamilton, 1822 (Teleostei: Cyprinidae)

Faal,

Esmaeili,

Teimori

et al. 2024

To evaluate scale morphological variability (shape, size, topological macro‐ and microstructures, ornamentation patterns) of cyprinid fishes, nine species of the genus Garra were selected and their scales from five different body regions were studied by using light and scanning electron microscopy. The scales of the examined species were thin with a central or antero–centrally positioned focus, with no cteni in the posterior part. In addition to these typical characteristics, some morphological variation was observed in the overall shape (irregular round, true oval, round‐triangular, irregular pentagonal, hexagonal, irregular hexagonal, pentagonal, ovoid), and the focus shape. These variations were mainly dependent on the fish lengths and the flank region. Morphological analysis clustered the examined species into two distinct groups. Group I consisted of G. amirhosseini and G. gymnothorax, while Group II has three subgroups, which include G. persica and G. mondica (subgroup I), G. meymehensis, G. rossica, G. nudiventris, G. hormuzensis (subgroup II), and G. rufa (subgroup III). The grouping of the studied Garra species based on the current scale morphological characters and the molecular data was only consistent for G. rossica and G. nudiventris. In addition, in the phylogenetic tree, G. persica, G. mondica, G. amirhosseini, and G. hormuzensis formed a distinct clade. However, these species did not represent close relationships in the dendrogram obtained from the scale morphology. A possible explanation why the grouping of the studied Garra species based on their scale morphological characters does not match their phylogenetic relationships is that most of the scale morphological traits vary depending on the fish size and the location of the scales on the flank. Therefore, except for some traits, that is, central or antero–centrally positioned focus, having no cteni, a specific sectioned form so called “tetra‐sectioned” type, the other examined variables are not useful enough to be used in the taxonomic study of the examined cyprinid fishes. Therefore, scale morphological characters should be used carefully for taxonomic purposes.Research Highlights Shape, size, topological macro‐ and microstructures, and ornamentation patterns of nine species of the genus Garra were studied by using light and scanning electron microscopy. The scales were thin with a central or antero–centrally positioned focus, with no cteni in the posterior part. Morphological variation was observed in the overall shape (irregular round, true oval, round‐triangular, irregular pentagonal, hexagonal, irregular hexagonal, pentagonal, and ovoid), and the focus shape. The grouping of Garra species based on the current scale morphological characters and the molecular data was only consistent for G. rossica and G. nudiventris.