A new species Unionicola (Dimockatax stat. rev.) haungthayawensis sp. nov. (Trombidiformes: Unionicolidae) from the freshwater mussel Lamellidens generosus (Gould, 1847) in Myanmar

Abstract

Unionicola (Dimockatax stat. rev.) haungthayawensis sp. nov. is described from the freshwater mussel Lamellidens generosus (Gould, 1847) (Bivalvia: Unionidae). The mites were collected from two sites in Myanmar. The mites were examined morphologically under the light microscope and their mitochondrial COI gene sequences have been obtained. Unionicola (Dimockatax stat. rev.) haungthayawensis sp. nov. is distinguished from another Asian member of the subgenus, U. (D.) tumidoides Vidrine, 1986, by the size of idiosoma (for males), and by the length of leg segments (for males and females) and chaetotaxy of the legs. Phylogenetic analysis reveals that these mites are phylogenetically close to two North American species belonging this subgenus, i.e. U. (Dimockatax stat. rev.) tumida (Wolcott, 1898) and U. (Dimockatax stat. rev.) ernstingi Edwards et al., 2009 (uncorrected COI p-distance = 13.6% and 17.3%, respectively). In this paper, we also restore Dimockatax Vidrine, 1992 stat. rev. as a valid subgenus, because it was supported by a broad-scale phylogenetic research.

New Molecular-Based Phylogeny of Mussel-Associated Mites Reveals a New Subgenus and Three New Species Representing an Example of a Host-Driven Radiation in Indochina and Confirms the Concept of Division of the Genus Unionicola Haldeman, 1842 (Acari: Unionicolidae) into Numerous Subgenera

“…Guided by these considerations, we have recently restored the subgenus Dimockatax when describing the new species, Unionicola (Dimockatax) haungthayawensis [14]. Now, we here restored the valid subgenera in this genus as follows: Unionicola Haldeman, 1842 stat.…”

“…Posterior coxal group without an apparent posterior apodeme, square or rectangular shape with rounded inner corners (females have more rounding along the inner caudal margin). Both male and female genital fields consist of a single pair of acetabular plates; genital acetabula with many pairs (13)(14)(15)(16)(17)(18)(19)(20) concentrated in anterior and posterior groups and may be without a distinct visible border between these groups; leg I with large setae; leg IV rather long, especially IV-L-5 noticeably longer than other segments, tarsus of every leg with bifid claws. Chaetotaxy of walking legs in females and males is different, P-3 with one seta for females and without setae for males; the idiosoma size for females is slightly larger than for males.…”

“…This genus comprises 58 subgenera with more than 260 Unionicola species [7,9,10]. Despite this fact, new species are still being described every year from different geographical localities according to the subtle differences in morphology and genetic data [7,[11][12][13][14]. Investigation of parasite species richness is a crucial step towards the evaluation of interactions between environment, chironomid and mussel hosts, and parasitic mites.…”

“…Furthermore, the discovery of the new subgenus and species, Unionicola (Gibbosulicola) sella Chapurina, Bolotov, Vidrine, Kondakov and Vikhrev, 2021, from the margaritiferid species Gibbosula laosensis (Lea, 1863) (Margaritiferidae: Gibbosulinae) suggests that all six families in the order Unionida are infected with Unionicola mites [7], although the family-group placement of some genera such as Acostaea d'Orbigny, 1851 is questionable [25,26]. Two new free-living species of Unionicola from Thailand were recently described [10], and one parasitic species has been recently described from Myanmar [14]. Our earlier study [7] showed that members of seven subgenera of parasitic Unionicola mites were recorded in Southeast Asia: Dimockatax Vidrine, 1992, Fulleratax Vidrine, 1984, Imamuratax Vidrine, 1994, Pentatax Thor, 1922, Prasadatax Vidrine, 1992, Unionicola Haldeman, 1842 (hosts: Unionidae), and Gibbosulicula Chapurina, Bolotov, Vidrine, Kondakov and Vikhrev, 2021 (hosts: Margaritiferidae) [7].…”

First record of Unionicola (Myanmaratax) savadiensis from India, with remarks on parasite-host relationship in unionicolid mites (Acari, Unionicolidae)

“…Chapurina et al (2022a, b) reported a number of species from Lamellidens Simpson, 1900 as gill mites from Myanmar, including U. diversipes, U. (Dimockatax) huangthayaensis (Chapurina et al, 2022b), U. (Myanmaratax) generosa Chapurina, Vidrine, Kondakov, Vikhrev & Bolotov, 2022(in Chapurina et al, 2022a and U.…”