Two new species of free-living marine nematodes of Adoncholaimus Filipjev, 1918 (Oncholaimida: Oncholaimidae: Adoncholaiminae) from Hokkaido, northern Japan, with a key to species and discussion of the genus

Abstract

Two new species of free-living marine nematodes, Adoncholaimus daikokuensis sp. nov. and A. pseudofervidus sp. nov., from the coastal area of northern Japan, are described and illustrated. Adoncholaimus daikokuensis sp. nov. is similar to five congeners, A. derjugini, A. punctatus, A. oxyuroides, A. squalus comb. nov. and A. fiUcauda comb. nov. in the absence of a gubemaculum, but differs in the absence of a ventral swelling on tail, spicule length and buccal cavity length. Adoncholaimus pseudofervidus sp. nov. is similar to A. fervidus in having large body size, short tail, similar positions of the excretory pore and nerve ring, short spicules, arrangement of subventral setae in posterior region of body in males, and a single pair of terminal pores of the Demanian system surrounded by small gland cells in females. Adoncholaimus pseudofervidus sp. nov. differs from A. fervidus in having smaller, more anteriorly located amphids, longer buccal cavity, absence of gubemaculum in the male, and a different position of the terminal pores in the female. Partial sequences of the mitochondrial cytochrome c oxidase subunit I gene (309-337 bp) of the new species are provided for identification based on the DNA barcoding method. Metoncholaimoides is proposed as a junior synonym of Adoncholaimus. The new diagnosis oí Adoncholaimus and a key to species are provided. Adoncholaimus squalus comb, nov., Adoncholaimus filicauda comb. nov., and Admirandus papillatus comb. nov. are proposed.

Checklist of the subfamily Adoncholaiminae Gerlach and Riemann, 1974 (Nematoda: Oncholaimida: Oncholaimidae) of the world: genera, species, distribution, and reference list for taxonomists and ecologists

“… Adoncholaiminae Type genus: Adoncholaimus Filipjev, 1918 = Metoncholaimoides Wieser, 1953 [by Shimada and Kajihara (2014) ] …”

“… Adoncholaiminae Gerlach and Riemann, 1974 is a subfamily of free-living aquatic nematode family Oncholaimidae Filipjev, 1916 (phylum Nematoda ). It consists of four genera ( Lorenzen 1981a , Lorenzen 1994 , Shimada and Kajihara 2014 ), viz. Adoncholaimus Filipjev, 1918, Admirandus , Belogurov and Belogurova 1979, Kreisoncholaimus Rachor, 1969, and Meyersia Hopper, 1967.…”

“… Adoncholaimus Filipjev, 1918, Admirandus , Belogurov and Belogurova 1979, Kreisoncholaimus Rachor, 1969, and Meyersia Hopper, 1967. Metoncholaimoides Wieser, 1953 has been placed in the subfamily before, but Shimada and Kajihara (2014) considered the genus as a junior synonym for Adoncholaimus . Adoncholaiminae morphologically differs from the other six subfamilies of family Oncholaimidae Filipjev, 1916 in the order Oncholaimida Siddiqi, 1983 and suborder Oncholaimina de Conink, 1965 (c.f.…”

“… Adoncholaiminae morphologically differs from the other six subfamilies of family Oncholaimidae Filipjev, 1916 in the order Oncholaimida Siddiqi, 1983 and suborder Oncholaimina de Conink, 1965 (c.f. Filipjev 1916 , Maggenti 1981 , Siddiqi 1983 , Smol and Coomans 2006 , Hodda 2011 , Shimada and Kajihara 2014 ) by the well developed sperm-storage organ (Demanian system) in the female ( Rachor 1969 , Belogurov and Belogurova 1977a , Belogurov and Belogurova 1977b , Belogurov and Belogurova 1977c , Belogurov and Belogurova 1977d , Belogurov and Belogurova 1989 , Smol and Coomans 2006 ), however there have been no molecular phylogenetic evidences at present. Nematodes belonging to Adoncholaiminae are found from all continents, from the equatorial tropic to the two poles.…”

“…Although many revisions of the specific genera or higher taxa with species lists and taxonomic keys (e.g. Greenslade and Nicholas 1991 , Huang and Cheng 2012 , Shimada and Kajihara 2014 ) have been published since 1974, full literature of them is not available today.…”