Phasmarhabditis thesamica n. sp. (Nematoda: Rhabditidae), a new slug nematode from southern slope of Caucasus, Georgia

Abstract

Summary Phasmarhabditis thesamica n. sp., belonging to the family Rhabditidae, was isolated from the bodies of the invasive slug, Deroceras reticulatum in Georgia. Nematodes of this genus have never been recorded previously in Georgia. Phasmarhabditis thesamica n. sp. was characterised at morphological, morphometrical and molecular level. Females are 2052 (1863-2241) μm long, lateral fields consisting of three protruding central ridges and four incisions. The vulval opening is in the middle of the body. The tail is conical, long, tapering to a filiform tip, with prominent rod-shaped phasmids. The reproductive system is didelphic-amphidelphic. Males are 1301 (1123-1456) μm long, with an open peloderal bursa, which is supported by nine pairs of genital papillae 1 + 1 + 1/2 + 1 + 3, and two phasmids located close to tail tip. The molecular phylogeny of P. thesamica n. sp. inferred by using ITS, D2-D3 expansion domains of the 28S rRNA gene and the 18S rRNA gene revealed close relationships with P. clausiliiae, with high support.

Synopsis of gastropod-associated nematodes of Ciscaucasia (Russian Federation) with the description of a new species of Pellioditis Dougherty, 1953 (syn. Phasmarhabditis Andrássy, 1976)

“…The analysis also grouped two other Caucasian species, P. clausiliiae and P. thesamica , which show close relationships with the exotic P. zhejiangensis , although with weak support. Our analysis is consistent with the data of Gorgadze et al 2022 who recently described P. thesamica from eastern Georgia. Thus, the present five Pellioditis species from the Caucasus form two subclades that are closest to the European P. pellio (previously described as P. bohemica ), P. neopapillosa, P. hermaphrodita , and P. villasmundi and at the same time, to Chinese P. zhejiangensis.…”

“…By the shape of the female tail, the present species is most similar to four other species from the Caucasus region, i.e., P. circassica Ivanova, Geraskina & Spiridonov, 2020, P. clausiliiae Ivanova, Geraskina & Spiridonov, 2020, P. akhaldaba Ivanova, Gorgadze, Lorthipanidze & Spiridonov, 2021, and P. thesamica Gorgadze, Troccoli, Fanelli, Tarasco & De Luca, 2022. While the female tails of P. circassica , P. clausiliiae and P. thesamica show little variation in shape, two discovered populations (strains ‘quick’ and ‘slow’) of P. akhaldaba show variation in female tail shape similar to P. thermalis sp.…”

Pellioditis pelhamin. sp. (Nematoda: Rhabditidae) andPellioditis pellio(Schneider, 1866), earthworm associates from different subclades withinPellioditis(syn.PhasmarhabditisAndrássy, 1976)

“…EM434 [6, 13, 15-17, 26, 43-54] = Phasmarhabditis sp. [55,56], using sequence accession numbers EU195967 and EU196008.  DF5056: leg.…”

Thirty years of slug control using the parasitic nematode Phasmarhabditis hermaphrodita and beyond

“…77 Nematodes from the genus Phasmarhabditis are problematic to classify as there are some poorly described species, but currently 18 species have been isolated from terrestrial gastropods, including P. apuliae, P. bohemica, P. bonaquaense, P. californica, P. circassica, P. clausilliae, P. hermaphrodita, P. meridionalis, P. neopapillosa, P. papillosa, P. safricana, P. akhaldaba, P. kenyaensis, P. thesamica, P. quinamensis, P. zhejiangensis and P. tawfiki, and one species (P. huizhouensis) from rotting leaf litter. [78][79][80][81][82][83][84][85][86][87][88][89][90][91] There were another two Phasmarhabditis species including P. nidrosienses (isolated from a marine habitat) and P. valida (isolated from littoral detritus), 92 but after revision they were moved to the genus Buetschlinema. 93 It is clear from the numerous surveys carried out over the last 30 years that Phasmarhabditis nematodes are commonly found in many countries from diverse terrestrial gastropod hosts.…”