Two New Marine Free-Living Nematodes from Jeju Island Together with a Review of the Genus Gammanema Cobb 1920 (Nematoda, Chromadorida, Selachinematidae)

Alexei Tchesunov,Raehyuk Jeong,Wonchoel Lee

doi:10.3390/d12010019

Alexei Tchesunov, Raehyuk Jeong + Show 1 more

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https://doi.org/10.3390/d12010019

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Journal: Diversity	Publication Date: Jan 1, 2020
Citations: 5	License type: CC BY 4.0

Affiliation: Lomonosov Moscow State University, Hanyang University

Abstract

In the context of exploration of meiofauna in a sandy intertidal zone of Jeju Island (South Korea), over 70 nematode species are identified, some which have been proven to be new for science. Two new free-living marine nematode species of the family Selachinematidae (Chromadorida, Selachinematidae, Choniolaiminae) are described from the intertidal sandy sediments of Jeju Island (South Korea). Gammanema okhlopkovi sp. n. is closest to Gammanema anthostoma (Okhlopkov, 2002) and differs by having longer cephalic setae (8.5–19 μm in G. okhlopkovi versus 6–7.5 μm in G. anthostoma) and by the presence of precloacal supplementary organs. The genus diagnosis of Gammanema is updated. The genus includes fourteen valid species, while three species are considered species inquirendae due to incomplete diagnoses and illustrations impeding their correct recognition. An annotated list of valid and invalid Gammanema species is provided. A pictorial key for valid Gammanema species is constructed, which consists of two components: (1) simplified images of heads, and (2) a table summarizing most of the significant measured and numeric characters between species. Latronema obscuramphis sp. n. differs from its related species Latronema aberrans (Allgén 1934), Latronema annulatum (Gerlach, 1953), and Latronema spinosum (Andrássy, 1973) by body size, number of supplementary organs, tail shape, length of spicules, and cuticle ornamentation.

Highlights

Gammanema species is constructed, which consists of two components: (1) simplified images of heads, and (2) a table summarizing most of the significant measured and numeric characters between species
Latronema obscuramphis sp. n. differs from its related species Latronema aberrans (Allgén 1934), Latronema annulatum (Gerlach, 1953), and Latronema spinosum (Andrássy, 1973) by body size, number of supplementary organs, tail shape, length of spicules, and cuticle ornamentation
Data on Jeju marine free-living nematodes have been presented by Rho and Kim [1,2], Rho et al [3], and Lim and Chang [4]

Summary

Introduction

Data on Jeju marine free-living nematodes have been presented by Rho and Kim [1,2], Rho et al [3], and Lim and Chang [4]. A taxonomic survey of Jeju nematodes started with the family Thoracostomopsidae by Jeong et al [5,6]. We present a communication on the family Selachinematidae. The selachinematid nematodes are usually characterized by a stout cylindrical body with a truncate anterior end. They have a complicated buccal armament of rhabdions, denticles, or heavy mandibles, enabling them to capture nematode prey. The percentage of selachinematids and other predator taxa in nematode assemblages are usually low in mud and silty

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