GENETIC DIVERSITY IN LUMBRICIDAE AND MEGASCOLECIDAE (OLIGOCHAETA) INFERRED FROM MITOCHONDRIAL DNA, WITH DESCRIPTION OF A NEW Aporrectodea longa AND NOTES ON Pithemera bicincta - Nazik M. Saeed Othman; Sherwan T. Ahmad; Sofyan H. Sedo (Journal of Animal and Plant Sciences, 2026)
<span style="font-size: 11.0pt; mso-bidi-font-size: 13.0pt; line-height: 107%; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-theme-font: major-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">Identification at a species level is one of the primary issues in earthworm species biodiversity, which restricts appropriate measurement of community structure and conservation level. Morphological characters together with molecular status, especially mitochondrial DNA markers have been useful to solve the ambiguous earthworm’s diversity. In this study, we examined the genetic diversity and phylogeny of earthworms in the Kurdistan Region of northern Iraq with reference to the mitochondrial cytochrome c oxidase subunit I (Cox1) gene. Between September 2024 and August 2025, a total of 200 earthworms were collected in various localities. Mitochondrial DNA was obtained using gizzard tissue, and a 523 bp fragment of Cox1 gene was amplified and sequenced. Three lumbricid species were identified through molecular identification that included: Aporrectodea trapezoides, Aporrectodea longa, and Pithemera bicincta. Maximum Likelihood method of phylogenetic analysis resulted in resolution of two major clades with the Iraqi isolates falling in the same clade as the Asian and European reference sequences. The haplotype network analysis revealed five haplotypes Hap_1-Hap_5 with Hap_1 being the most widespread in the areas of Iraq, Europe, Asia, and North America, which indicates extensive dispersal and high genetic connectivity. <span style="font-size: 11.0pt; mso-bidi-font-size: 13.0pt; line-height: 107%; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-theme-font: major-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-AE;">The haplotype diversity was moderate (Hd = 0.39), whereas the nucleotide diversity was high (π = 0.10), meaning that there was a significant sequence divergence between the taxa analyzed. In terms of neutrality tests, Tajima D was negative (-1.59) that implies the existence of more rare alleles that could be connected to the demographic growth or selection.<span style="font-size: 11.0pt; mso-bidi-font-size: 13.0pt; line-height: 107%; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-theme-font: major-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;"> <span style="font-size: 11.0pt; mso-bidi-font-size: 13.0pt; line-height: 107%; font-family: 'Times New Roman',serif; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-theme-font: major-bidi; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-AE;">Our results represent the initial molecular validation of P. bicincta in Iraq and expand the known range of A. longa. In general, the results provide novel molecular information on earthworm’s diversity in Iraq.
Keywords: journal article; Earthworms; Aporrectodea trapezoides; Aporrectodea longa; Pithemera bicincta; Cox1 gene; phylogenetic analysis; Genetic diversity