Morphological description and molecular identification ofMyxobolus dajiangensisn. sp. (Myxozoa: Myxobolidae) from the gill ofCyprinus carpioin southwest China

Abstract

Background Myxosporean diversity is a hot topic since they are difficult to accurately identify and classify. Many Myxobolus parasites have been named as Myxobolus koi because of their similar morphological features with the species originally reported. However, the distinctions in fine morphological features, host specificity, and molecular data have given rise to the attention of researchers. Methods The classical morphometric and histological methods were used to describe the Myxobolus dajiangensis n. sp. in morphology. The common techniques in modern molecular biology and the methods of phylogenetic analyses were combined to identify the species. Results Plasmodia of interlamellar-vascular type were found in the vascular network of gill lamellae. Mature myxospores of M. dajiangensis n. sp. were elongated and pyriform from the frontal view. The myxospores were 14.8 ± 0.4 (13.9–15.6) µm in length, 8.0 ± 0.5 (7.2–9.1) µm in width, and 5.5 µm in thickness. The two polar capsules were pyriform and slightly different in length. The length of the larger polar capsules was 8.0 ± 0.4 (7.1–8.8) µm, and it was 7.4 ± 0.4 (6.1–8.0) µm for the smaller ones. The width of both polar capsules was 2.5 ± 0.2 (2.0–3.2) µm. The polar filaments within the polar capsules were each coiled nine to 11 turns. Comparative analysis of both the morphological and molecular data between the present speices and other similar species revealed that the present species is a novel species, Myxobolus dajiangensis n. sp. Also, M. koi (FJ710800) was misidentified and the congener with M. dajiangensis n. sp., depending on the secondary structures of SSU rRNA and phylogenetic analysis. Moreover, the cryptic species existed in the M. koi parasites.

Myxobolus xiushanensis n. sp. (Myxozoa: Myxobolidae) infecting the gill arches of Yellowhead Catfish Tachysurus fulvidraco from China

“…Moreover, an increasing number of novel Myxobolus species are being recognized with constant depth and expansion in related research fields. At present, a combination of morphological traits, molecular data, host preference, and parasite tropism contributes to the identification of novel species and the discrimination of morphologically similar species (Zhao et al 2013; Fiala et al 2015; Liu et al 2019b; Wang et al 2022).…”