Three new species of Mesacanthion Filipjev, 1927 (Nematoda: Thoracostomopsidae) from Argentine coasts

Three new species of Mesacanthion Filipjev, 1927 were found along Patagonian coasts (Argentina). Mesacanthion bifidum sp. nov. is characterized by short labial and cephalic setae, onchia of equal size, spicule arcuate, and gubernaculum with caudal apophysis, ending in two teeth. The species is related to M. virile (Ditlevsen, 1930) De Coninck & Schuurmans Stekhoven, 1933. However, the spicules and gubernaculum of both species are different in shape. Mesacanthion longigubernaculum sp. nov. is characterized by its long and slender body, striated cuticle, relatively long cephalic and cervical setae, onchia of different sizes, amphidial fovea lentil-shaped, spicule arcuate, gubernaculum surrounding the spicule, and tail conical-cylindrical with terminal setae. Mesacanthion sanantoniensis sp. nov. is characterized by its long and stout body, striated cuticle, long cephalic setae, onchia of different sizes, amphidial fovea pouch-shaped, spicule arcuate, gubernaculum with dorsal apophysis, and tail conical without terminal setae. Following the key of Jeong et al. (2019), the last two species are related to M. pali Wieser, 1959 and M. longissimesetosum Wieser, 1953, so we provide a key to differentiate the four species.

Two new and two known species of the genus Paraoxydirus Jairajpuri and Ahmad, 1978 (Nematoda: Dorylaimida) from Western Ghats of India

Summary Two new and two known species of the genus Paraoxydirus Jairajpuri and Ahmad, 1978 are described and illustrated from Western Ghats of India. P. vulvalpapillatus n. sp. is characterized by having large sized body (L = 4.6 – 4.8 mm); lip region continuous with completely amalgamated lips; amphidial fovea cup – shaped; 5 – 6 μm long odontostyle; 11 – 13 μm long odontophore; pharyngeal expansion about 28 – 36 % of neck length; transverse vulva; vulval papillae conspicuous; males with 46 – 54 μm long spicules; 11 – 14 continuous ventromedian supplements and long filiform tail similar in both sexes. P. indicus n. sp. is characterized by having large sized body (L = 4.0 – 4.8 mm); lip region poorly offset with amalgamated lips; amphidial fovea cup-shaped; 7 – 8 μm long, robust odontostyle; 17 – 18 μm long odontophore; pharyngeal expansion about 32 – 40 % of neck length; 21 – 26 μm long cardia; longitudinal vulva; 748 – 894 μm long filiform tail; males with 45 – 54 μm long spicules and 12 – 15 continuous ventromedian supplements. P. gigas Jairajpuri, 1964 and P. novus Jairajpuri, 1965 are redescribed based on specimens collected from several localities. A diagnostic Key and compendium to the identification of its eight valid species is provided.

Descriptions of Deontolaimus holovachovi sp. nov. and Campylaimus zhoui sp. nov. from Chinese sea areas

Two new species of free-living marine nematode discovered from an intertidal sandy beach in the Bohai Sea and from a sublittoral region in the East China Sea are described. Deontolaimus holovachovi sp. nov. is characterized by short cephalic setae (2.5–3 μm long); ventrally-unispiral amphidial fovea; excretory pore located at the level with nerve ring; lateral alae present; two pairs of lateral cervical setae present; arcuate spicules 1.5–1.6 cloacal body diameter long, with the proximal half swollen and proximal end hooked, the distal half narrow; gubernaculum with dorso-caudal apophysis; postcloacal sensilla present in males; a midventral caudal papilla with a short seta situated at posterior third of tail length. Campylaimus zhoui sp. nov. is characterized by loop-shaped amphid with very long ventral limb extending along pharyngeal region to level of anterior part of intestine, 4.7–5.2 times the length of dorsal limb; excretory pore opening posterior to the pharyngo-intestinal junction; spicules symmetrical, slightly arcuate without proximal capitulum; gubernaculum with small dorsal apophysis; precloacal supplements absent.

Further data on Iranian marine nematode diversity, with description of three new Desmodoridae Filipjev, 1922 (Nematoda: Desmodorida) species from the Persian Gulf

Summary The Desmodoridae is a diverse and widespread family of free-living nematodes. Here, we provide the first record of the group in the Persian Gulf and describe three new species: Metachromadoroides sinuspersici sp. n., Zalonema iranicum sp. n. and Z. supplementorum sp. n. Metachromadoroides sinuspersici sp. n. is characterised by finely annulated cuticle, short and stout cephalic sensilla, amphidial fovea on cuticular thickening, pharyngeal bulb well developed and partitioned into three sections, absence of precloacal supplements, and presence of 6-8 pairs of rounded postcloacal papillae. Zalonema iranicum sp. n. is characterised by papilliform subcephalic sensilla (best observed with SEM), convex cephalic capsule, large multispiral amphidial fovea with 4-5 turns in both males and females, buccal cavity with one ventrosublateral and two dorsal teeth and posterior body of males with lateral alae extending from the last third of the body to the cloacal aperture and ventral alae extending 1395-2250 μm anterior to the cloacal aperture, and no precloacal supplements. Zalonema supplementorum sp. n. is characterised by four subcephalic sensilla 1-2 μm long, multispiral amphidial fovea with three turns in both males and females, buccal cavity with one dorsal and two ventrosublateral teeth, males with lateral alae present on each side of body from posterior half of body to cloacal aperture, ventral alae extending 942-1257 μm anterior to cloacal aperture, strongly cuticularised spicules 41-43 μm long, and 12-16 precloacal supplements. Near full length SSU and partial D2-D3 LSU sequences are provided for M. sinuspersici sp. n. and Z. iranicum sp. n., and the COI sequence is provided for Z. iranicum. The SSU phylogeny suggests a close relationship between M. sinuspersici sp. n. and Metachromadora and Metachromadoroides species and the monophyly of Zalonema (after currently available data). The LSU phylogeny suggests an affinity between Metachromadoroides and Zalonema with Spirinia and Acanthopharynx, respectively.

Morphological and molecular characterisation of populations of Longidorus longicaudatus Siddiqi, 1962 and L. americanus Handoo, Carta, Skantar, Ye, Robbins, Subbotin, Fraedrich & Cram, 2005 from Florida, USA

Summary Two populations of needle nematode, Longidorus longicaudatus Siddiqi, 1962, are described from Quercus hemisphaerica, Q. nigra and Q. virginiana from north Florida, USA. These populations are characterised morphologically by females having a body shorter than 3800 μm, a rounded or slightly flattened lip region, an amphidial fovea pouch-like often with two symmetrical lobes, an odontostyle 99-110 μm long, a conoid tail ending in a bluntly pointed terminus, ranging values of ratio c′ greater than 2, and males very rare. The polytomous code for these populations is A34, B23, C2, D23, E2, F12, G12, H6, I12, J1, K6. Although the morphology and morphometrics of these two populations fit the original description of Longidorus longicaudatus, Florida specimens have greater diameters of lip region, mid and anal body than those of the five type specimens used for the description of this species. The Florida L. longicaudatus is similar to L. paralongicaudatus, but differs from the paratypes of this species in having smaller and greater values of ratios c (53.8 (43.8-64.5) vs 79.2 (61.9-103.5)) and c′ (2.4 (2.1-2.9) vs 1.8 (1.5-2.0)), respectively, and longer tail (60 (53-67) vs 46 (36-53) μm). Molecular characterisation of one of the two Florida L. longicaudatus populations was made based on the D2-D3 of 28S rRNA, ITS1 rRNA and COI gene sequences. The results of the ITS1 rRNA gene sequence analysis indicated that it is genetically different from L. paralongicaudatus. A few specimens of a needle nematode associated with L. longicaudatus were identified morphologically and molecularly as the pine needle nematode, L. americanus. This detection is a new record of the occurrence of the pine needle nematode in Florida.

Sigmolenchus sinuosus n. gen., n. sp. (Tylenchidae: Ecphyadophorinae), a new member of the family

Summary Sigmolenchus n. gen., is proposed as a new member of the Tylenchidae. The new genus is proposed based upon light and scanning electron microscopic (LM and SEM) observations and phylogenetic analyses based upon small, large and internal transcribed spacer sequences of ribosomal DNA (SSU, LSU D2-D3, ITS rDNA) and mitochondrial cytochrome c oxidase I gene (COI mtDNA) sequences. It is characterised partly by its slender body, but mainly by having a dorso-ventrally flattened, smooth and elevated cephalic region, unique elongate sinuous amphidial openings, each appearing as a wavy slit with three peaks, originating from the vicinity of the labial plate, extending posteriorly and reaching and passing the first body annulus, and a spacious amphidial fovea. It has an anteriorly rounded outline under LM, knobbed stylet, its conus comprising about one-third of the total length, lateral field with a single band, metacorpus with a distinct valve, vulva with small lateral flaps, and males common with tylenchoidiform spicules. The new genus is morphologically compared with seven tylenchid genera, viz., Chilenchus, Ecphyadophoroides, Filenchus, Labrys, Lelenchus, Sakia, and Tenunemellus, mainly by having small slender body and dorso-ventrally flat cephalic region, and is placed under the subfamily Ecphyadophorinae because of its slender body, elevated smooth cephalic region, long amphidial openings and spacious amphidial fovea. It was recovered from marine muddy sediments taken 2 m deep in mangrove forests off southern Iran. Currently S. sinuosus n. gen., n. sp. is monotypic. In SSU phylogeny, the new genus formed an unsupported sister relationship with Filenchus discrepans, and in LSU phylogeny it occupied a placement inside a major clade including several Tylenchinae genera.

A new species of Microlaimus de Man 1880 (Nematoda: Microlaimidae) from the Black Sea

Microlaimus sergeevae sp. n. is described and illustrated from the Crimea shelf of the Black Sea. It is characterized by the 1301–1728 μm long body; cuticle with distinct annuli; spicules 34–37 μm long, curved; gubernacular apophyses 20–25 μm long, surrounding distal end of spicules; criptocyrcular amphidial fovea 7–8 μm in diameter; cervical setae present; four submedian rows of pores spreading along the whole body length, and eight precloacal supplements in males. The new species morphologically resembles M. gerlachi Wieser 1954, M. paraborealis Allgen 1940a and M. kaurii Wieser 1954, but differs from them by the length of cephalic setae, size of the body, presence of cervical setae, shape of the gubernacular apophyses, eight tubular precloacal supplements and submedian rows of pores spreading along the whole body length. M. sergeevae sp. n. differs from M. gerlachi by having a smaller amphidial fovea, shorter spicules and gubernacular apophyses. The new species differs from M. paraborealis by having larger value of c. It differs from M. kaurii by having longer spicules and larger values of c and b.

Four new species of free-living nematodes from shallow continental shelf of Portugal

Free-living marine nematodes of continental shelf of Portugal were studied through the goals of the Marine Biodiversity Information System Project (M@rbis 2015). Four species unknown to science and belonging to the families Axonolaimidae, Chromadoridae, Desmodoridae and Xyalidae are described. Besides Hypodontolaimus golikovy, Hypodontolaimus portuguese sp. n. is the only species in this genus which lacks precloacal supplements and gubernaculum but differs from the former mainly in cephalic setae length and amphidial fovea features. Metachromadora aliusa sp. n. doesn’t have a unique diagnostic character, differing in many aspects from the other species of the genus instead, mainly teeth number in the buccal cavity, size of the cephalic setae and the amphidial fovea, velum presence in the spicules, number and shape of the precloacal supplements. The main character of Odontophora sinapophysis sp. n. is the absence of apophysis in the gubernaculum. Stylotheristus multipapillatus sp. n. is characterized by the presence of precloacal supplements (papilliform) and the gubernaculum formed by only a piece.

Morphological and molecular characterisation of Longidorus pinus sp. n. (Nematoda: Longidoridae) from China and a key to known species of Longidorus in China

Summary Longidorus pinus sp. n. from China is characterised by females 3.3-4.9 mm long; lip region 8-12 μm diam., distinctly offset by a constriction; amphidial fovea pocket-shaped without basal lobes; a short odontostyle (67-81 μm); anteriorly located guide ring (30-38 μm); and short and conoid tail (31-40 μm long, c = 84-138, c′ = 1.2-1.9), with one or two pairs of caudal pores on each side. Males were not found. Three developmental juvenile stages were identified, the first-stage juvenile with conoid tail (c′ = 2.4-2.9). The polytomous key codes for the new species are: A2(3), B1, C23, D4, E1, F2, G23, H23, I1, J2, K6. Molecular phylogenetic analyses based on SSU, D2-D3 of LSU, ITS1 and ITS2 rDNA sequences indicate that L. pinus sp. n. is closely related to L. hangzhouensis, L. asiaticus, and L. camelliae, all of which apparently share a common Asiatic geographic origin. In addition, a key for identification of Longidorus found in China, based on morphological characters of both female and first-stage juvenile, is provided.

Belgopeltula belgica (Vincx & Gourbault, 1992) gen. et comb. nov. and Mudwigglus micramphidium sp. nov. from the west coast of Sweden, and reappraisal of the genus Pseudaraeolaimus Chitwood, 1951 (Nematoda: Araeolaimida: Diplopeltidae)

Two species of the nematode family Diplopeltidae are described from Skagerrak. The new genus Belgopeltula gen. nov. is proposed for Diplopeltula belgica Vincx & Gourbault, 1992 and is characterised by: amphidial fovea circular in female and double-loop-shaped in male; excretory pore located at the level of cephalic setae bases; oral opening on the dorsal side of the body; pharynx subdivided into strongly muscularised fusiform corpus and weakly muscularised narrow and long postcorpus; female didelphic with antidromously reflexed ovaries; supplements absent. Mudwigglus micramphidium sp. nov. is characterised by: a body of 0.6 mm long; cephalic sensilla 1.5 µm long; amphidial fovea loop-shaped, 8 µm long and 3.5 µm wide; gymnostom without cuticularised ring; tail elongate conoid, with subcylindrical distal part; terminal setae absent; spicules 15 µm long; gubernaculum present; two midventral precloacal setae. It is distinguished from M. macramphidium Leduc, 2013 in having shorter amphidial fovea, shorter spicules and presence of two precloacal setae. Redescription of Diplopeltis cylindricauda Allgén, 1932 is provided based on type material. Diplopeltula minuta Vitiello, 1972 is transferred to the genus Mudwigglus Leduc, 2013. Diplopeltis cylindricauda Allgén, 1932, Diplopeltula laminata Vitiello, 1972 and Diplopeltula cassidaignensis Vitiello, 1972 are transferred to the genus Pseudaraeolaimus Chitwood, 1951.