Iranian Journal of Ichthyology

DNA barcoding confirms the presence of a cryptic fish species, the floral blenny Petroscirtes mitratus (Teleostei: Blenniidae: Blenniinae) at Qeshm Island, Persian Gulf

Hamid Reza ESMAEILI — 2026-02-27

The floral blenny, Petroscirtes mitratus, is a widely distributed comb-tooth blenny in the Indo-West Pacific, previously reported from the southern Persian Gulf and the Oman Sea. However, its presence in the northern Persian Gulf had remained undocumented. This study provides the first confirmed record of this species from the northern Persian Gulf, based on a specimen collected from the intertidal zone of Qeshm Island, Iran. The identification was confirmed through an integrative taxonomic approach. Detailed morphological and meristic examinations aligned with the diagnostic characteristics of the species, including the distinctive notched dorsal fin and a dark spot on the pelvic fin. DNA barcoding of the mitochondrial COI gene provided molecular validation, with the obtained sequence forming a clade (bootstrap >80%) with other conspecific sequences from across its range. The genetic analysis also revealed clear differentiation from other Petroscirtes species. The study underscores the utility of combining morphological and molecular tools for accurate species identification in crypto-benthic fishes and has important implications for regional biodiversity assessments and conservation planning.

Taxonomical perspective of osteological features in Garra arunachalensis (Nebeshwar & Vishwanath, 2013), a native hill stream fish of upper Brahmaputra basin, India

Mintumoni PEGU — 2026-06-24

The genus Garra of Cyprinidae family comprises of 170 species inhabiting in the subtropical and tropical regions of Africa, Asia and Middle-eastern countries. The genus is specialized in having lower lip modified into mental adhesive disc which help the fishes in thriving fast flowing mountain streams. This study provides a comprehensive osteological description of Garra arunachalensis by using double staining method for skeletal visualization. Twenty specimens were used to study the structures of neurocranium, infraorbital series, branchial apparatus, axial skeleton, and fin structures of the species. Comparative analysis with congeners revealed similarities in neurocranium, branchial apparatus and pectoral and pelvic radial bones with species like G. mullya, G. annandalei and G. rossica while some notable differences were also found in hypural plates of caudal fin skeleton, number of axial skeletons, fin ray counts and infraorbital elements with the species like G. persica. The findings will underscore the utility of osteological characters in resolving taxonomic and phylogenetic complexities within the genus Garra for further systematics and evolutionary investigations.

The olfactory organ of long whiskered catfish, Mystus gulio (Hamilton, 1822): histomorphology and ultrastructure

Saroj Kumar GHOSH — 2026-06-24

The olfactory organ of the predatory catfish, Mystus gulio (Siluriformes: Ailiidae) was investigated through light microscopy and electron (scanning and transmission) microscopy to elucidate its structural organization. The olfactory rosette was elongated, comprising 32 to 38 lamellae arranged along a central midline raphe. Each olfactory lamella consisted of two principal parts: the olfactory epithelium (mucosa) and the median raphe. The mucosa displayed a clear demarcation into sensory and nonsensory zones, both exhibiting distinct cellular compositions that could be identified based on histoarchitectural features, staining affinities, surface morphology, distributional arrangement and ultrastructural characteristics. The sensory mucosa contained three types of receptor cells: two classical forms bearing either cilia or microvilli, and a third characterized by rod-shaped apical specialization. The nonsensory mucosa comprised mucous cells, chloride-like cells, rodlet cells and mast cells, along with two types of supporting cells categorized as either ciliated or non-ciliated. Basal cells were situated deep within the olfactory mucosa, adjacent to the central core. Structurally, the raphe was formed by compactly arranged stratified epithelial cells exhibiting distinct microridges on the apical membrane. The study discussed the functional relevance of the diverse cell types forming the olfactory mucosa, emphasizing their specific roles in the olfactory perception of Mystus gulio.

Microplastic contamination in the gastrointestinal tract of Common Kilka (Clupeonella cultriventris) caught of the Kiashahr coast (Southeastern Caspian Sea)

Raheleh MOTAMED — 2026-07-01

Microplastics, as emerging contaminants in aquatic ecosystems, have the potential to transfer through food webs. This study aimed to determine the relative frequency of shape, size, color, and polymer type of microplastics present in the gastrointestinal tract of common kilka (Clupeonella cultriventris) from the Kiashahr coast (southeastern Caspian Sea) during winter and summer seasons. Sampling was conducted in winter at six stations (S1 to S6) and in summer at two stations (S1 and S2). After dissection, the gastrointestinal tract of 80 fish specimens was digested using 30% H₂O₂ and separated via flotation in NaCl solution. Microplastics were categorized by shape (fibers, fragments, films, foams), size (five classes), color (five groups), and polymer type (determined by FTIR spectroscopy). At all stations and in both seasons, fibers were the dominant shape (winter: 65–75%; summer: approximately 63%). The size class of 500–1000 µm exhibited the highest frequency (winter: 40–50%; summer: 46–49%). Black color consistently showed the highest percentage (winter: 45–50%; summer: 45–47%). Polyethylene (PE) was the dominant polymer (winter: >40%; summer: 43–47%), followed by polypropylene (PP). No significant difference was observed among stations regarding the distribution of microplastic characteristics (P>0.05). Microplastic contamination in Kiashahr, kilka exhibits a uniform seasonal and spatial pattern, indicating a widespread and persistent source of pollution. Black polyethylene fibers measuring 500–1000µm were identified as the most common contaminant type. Controlling the input of municipal wastewater and fishing-related waste into the sea appears essential.