New species of free-living aquatic nematodes from south-western Australia (Nematoda: Axonolaimidae and Desmodoridae)

Abstract

-Descriptions of 10 new species of free-living aquatic nematodes are presented. Four of the new species belong to the Axonolaimidae, i.e. Ascolaimus australis, Parascolaimus brevisetus, Odontophora serrata and Parodontophora aurata. The remaining six species belong to the Desmodoridae, i.e. Bolbonema spiralis, Onyx cephalispiculus, O. potteri, Eubostrichus otti, Catanema australis and Leptonemella peronensis. All 10 species were found in sediments taken from near-shore waters of either the Swan River Estuary or marine waters of the Perth region (Western Australia). Ascolaimus australis differs from its only congener A. elongatus in that its spicules are non-barbed and have rounded proximal cephalations. Parascolaimus brevisetus is different from its four other congeners by its short cephalic setae, which are less than one quarter the length of any other Parascolaimus, and the spicule cephalations are rounded rather than simple or spade-shaped. Parodontophora aurata is distinguished from six morphologically similar species by the unique arrangement ((4D-2V)2) and greater length (6 µm) of the opisthocephalic setation. Odontophora serrata is distinct from other Odontophora species in that each odontiuim bears seven dentate projections, which is more projections than similar species, O. bermudensis (5), O. villoti (3) and O. paravilloti (3). Bolbonema spiralis has spiral amphids with two turns, in contrast to those of B. longisetosum, which are only a single loop. Onyx cephalispiculus is most similar to O. sagittarius but has more robust spicules with large, bilobed cephalations. Onyx potteri is the only Onyx species to exhibit spicules with a distinct constriction and one of only two species with ten tubular precloacal supplements. The other, O. dimorphus, has sexually dimorphic amphids whereas O. potteri does not. Eubostrichus otti is most similar to E. topiarus but is only half the size. Cephalic setation is also divergent, with E. otti having two cephalic crowns, eight setae in the anterior, four in the posterior, whereas this arrangement is reversed for E. topiarus. Catanema australis is most similar to C. exilis but is distinguished from that species by the lack of prominent, tubular, postcloacal supplements and having only four pairs of normal setae on the tail. Leptonemella peronensis is most similar to L. granulosa but differs in its non-granular cephalic capsule, shorter tail and different circumcloacal setation (two precloacal, four postcloacal and one terminal double pair v. L. granulosa's seven postcloacal pairs).

Onyx disparamphis sp. n. (Nematoda, Desmodorida) from South Korea with a taxonomic review of the genus

“…Onyx cephalispiculus Hourston & Warwick, 2010 . Hourston & Warwick, 2010 : 56–58, fig. 6 A–C, Table 7 (males, females); south-western Australia, subtidal sediment of heterogeneous grain size with low to moderate particulate organic content.…”

Two New Species of Free-living Marine Nematodes (Nematoda: Axonolaimidae and Tripyloididae) from the Coast of Antarctica

“…We add four valid species: O. sinapophysis Pinto and Neres, 2020, which was described after the work by Leduc and Zhao (2016); O. hawksbiensis Turpeenniemi, Nasira, andMaqbool, 2001, andO. serrata Hourston andWarwick, 2010, which were overlooked by Leduc and Zhao (2016); and O. polaris (Cobb, 1914), which De Coninck andSchuurmans Stekhoven (1933) regarded as a species inquirenda. Zhao (2016) followed De Coninck andSchuurmans Stekhoven (1933), probably because of the incomplete original description by Cobb (1914) based only on an immature specimen, although Cobb (1930) and Timm (1978b) later provided descriptions of both sexes.…”

“…longicaudata Schuurmans Stekhoven and De Coninck, 1933 to be a species inquirenda, because this species was established based only on a juvenile. Thus, the genus Odontophora now contains the following 36 valid species (Cobb 1914;Turpeenniemi et al 2001;Hourston and Warwick 2010;Leduc and Zhao 2016;Pinto and Neres 2020).…”

“…Scale bars: A-G, J, K, 10 µm; H, I, 5 µm. (Luc and De Coninck 1959;Gerlach 1962;Vitiello 1971;Blome 1982;Keppner 1988); O. articulata, O. bermudensis, and O. carrolli, five cusps (Jensen and Gerlach 1976;Keppner 1988); and O. serrata, seven cusps (Hourston and Warwick 2010). Species in Odontophoroides and Synodontium Cobb, 1920, also have bicuspidate odontia, but differ from O. odontophoroides sp.…”

Review ofOnyxCobb (Nematoda: Desmodoridae) with description of two new species from the Yellow Sea, China

“…Samples were stratified by 0–2, 2–8 cm and fixed with 5% formalin in seawater respectively for long-term preservation. In the laboratory, samples were stained with 0.1% rose bengal for 24 h (Higgins & Thiel, 1988). The samples were washed to remove the formalin and sieved over two mesh sizes (500 and 42 μm) in order to separate the macrofauna (500 μm) from the meiofauna (42 μm).…”