Morphological characterization of Chironomidae (Diptera) larvae in Anzali Wetland, Southwest Caspian Sea: First record of Chironomus plumosus

Abstract

Chironomids (Diptera) include the most abundant group of macroinvertebrates. They are usually collected from aquatic environments for quality evaluation. Tolerant aquatic organisms such as Chironomids are more abundant in polluted sites. This note makes the Chironomids as an excellent bioindicators. This group is not characterized in Anzali Wetland as well. So that, the aim of this study was to recover and characterize chironomidlarvae in this wetland. Hence, Chironomidlarvae were collected on the seasonal basis from 13 stations in the wetland. The main characteristics for their identification were eye spot, mentum, ventromental plate, antenna, and ventral tubules. The mitochondrial cytochrome oxidase I (COI) gene was applied to simplify the identification of Chironomus species by polymerase chain reaction (PCR) and sequencing method. The nucleotide sequence alignments were used for construction of the phylogenetic trees based on maximum likelihood method. Six genera were identified in three subfamilies, including: Chironominae (1 genus), Orthocladinae (1 genus), and Tanypodinae (4 genera). Based on ventral tubules, the dominant population of Chironomus larvae found in this study, lie in thummi and plumosus types. Five genera were reported for the first time from Anzali Wetland. The dominant genus was Chironomus. These groups of larvae were ultimately identified as Chironomus plumosus reporting for the first time from the wetland. It was also found that the Chironomids diversity is higher than those described in few studies before, however, further studies are still needed.