New data on two remarkable Antarctic species Amblydorylaimus isokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpus paradoxus (Loof, 1975), gen. n., comb. n. (Nematoda, Dorylaimida)

By

Elshishka, Milka
Lazarova, Stela
Radoslavov, Georgi
Hristov, Peter
Peneva, Vlada

Type

Article

Date of Publication

2015

Original Publication

ZooKeys

Volume

511

Pages

25-68

Subjects

18S rDNA , D2-D3 28S rDNA , Morphology , new geographic records , Nomenclature , SEM , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.511.9793

 

Abstract

The taxonomic position of two antarctic dorylaimid species Amblydorylaimus isokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpus paradoxus (Loof, 1975), gen. n., comb. n. are discussed on the basis of morphological, including SEM study, morphometric, postembryonic and sequence data of 18S rDNA and the D2-D3 expansion fragments of large subunit rDNA. The evolutionary trees inferred from 18S sequences show insufficient resolution to determine the assignment of the two species to particular families, moreover P. paradoxus gen. n., comb. n. (=Rhyssocolpus paradoxus) previously regarded as a member of Nordiidae or Qudsianematidae, showed distant relationship both to Rhyssocolpus vinciguerrae and Eudorylaimus spp. The phylogram inferred from 28S sequences revealed that A. isokaryon is a member of a well-supported group comprised of several Aporcelaimellus spp., while, no close relationships could be revealed for the P. paradoxus gen. n., comb. n. to any nematode genus. On the basis of molecular data and morphological characteristics, some taxonomic changes are proposed. Amblydorylaimus isokaryon is transferred from family Qudsianematidae to family Aporcelaimidae, and a new monotypic genus Pararhyssocolpus gen. n. is proposed, attributed to Pararhyssocolpidae fam. n. The diagnosis of the new family is provided together with emended diagnosis of the genera Amblydorylaimus and Pararhyssocolpus gen. n. Data concerning distribution of these endemic genera in the Antarctic region are also given.