Description of Laimaphelenchus piceae sp. n., a new evidence of cryptic speciation, and L. sinensis Gu et al., 2020 (Rhabditida: Aphelenchoididae), a record from Shanxi province, north China

This contribution deals with the record and description of one new species and record of one known species of the genus Laimaphelenchus from Shanxi province, north China. The type population of L. piceae sp. n. is characterised by having females 642-807 μm long, the cephalic region with six labial sectors divided by ribs, stylet 12-14 μm long, lateral field with four incisures, postvulval uterine sac (PUS) 114-161 μm long, vulva with a well-developed anterior flap, tail with a single stalk at tip, bearing four pedunculate tubercles, each tubercle including 5-7 finger-like protrusions; males spicules 18-24 μm long and three pairs of caudal papillae present. The new species looks closely similar to L. persicus, representing its cryptic species, being separated by differences in some morphological indices and partial large subunit (LSU) rDNA sequences. Its morphological differences from other relevant species were discussed. L. sinensis was also recorded from Shanxi province for the first time. The phylogenetic relationships of the recovered populations were reconstructed using sequences of the near full length small subunit (SSU) and D2-D3 segments of LSU rDNA, and the relationships of both species were discussed.

Description of Longidorus bordonensis sp. nov. from Portugal, with systematics and molecular phylogeny of the genus (Nematoda, Longidoridae)

The genus Longidorus currently comprises 176 species of polyphagous plant ectoparasites, including eight species that vector nepoviruses. Longidorus is one of the most difficult genera to accurately identify species because of the similar morphology and overlapping measurements and ratios among species. Sequences of ribosomal RNA (rRNA)-genes are a powerful level-species diagnostic tool for the genus Longidorus. From 2015 to 2019, a nematode survey was conducted in vineyards and agro-forest environments in Portugal. The populations of Longidorus spp. were characterized through an integrative approach based on morphological data and molecular phylogenetic analysis from rRNA genes (D2-D3 expansion segments of the 28S, ITS1, and partial 18S), including the topotype of L. vinearum. Longidorus bordonensissp. nov., a didelphic species recovered from the rhizosphere of grasses, is described and illustrated. Longidorus vineacola, with cork oak and wild olive as hosts, is also characterized. This is the first time that L. wicuolea, from cork oak, is reported for Portugal. Bayesian inference (BI) phylogenetic trees for these three molecular markers established phylogenetic relationships among the new species with other Longidorus spp. Phylogenetic trees indicated that i) L. bordonensissp. nov. is clustered together with other Longidorus spp. and forms a sister clade with L. pini and L. carpetanensis, sharing a short body and odontostyle length, and elongate to conical female tail, and ii) all the other species described and illustrated are phylogenetically associated, including the topotype isolate of L. vinearum.

Morphological and Molecular Characterization of Paralongidorus sali Siddiqi, Hooper, and Khan, 1963 with a Description of the First-Stage Juvenile and Male of Longidorus jonesi Siddiqi, 1962 from China

Longidorids are economically important plant-parasitic nematodes because several species are virus vectors. Populations of Paralongidorus sali and Longidorus jonesi , isolated from woody perennials of Hangzhou, Zhejiang, China, were characterized molecularly and morphologically. The morphometric data of the Chinese populations of both species were compared with other populations. The present study provided a first record of the occurrence of Paralongidorus in China coupled with description of the first-stage Juvenile and male of L. jonesi . Phylogenetic analysis based on 18S and D2-D3 expansion segments of 28S gene indicated that L. jonesi clustered with L. jonesi reported from Japan and P. sali grouped with P. bikanerensis from Iran. Considering the pathological and economic importance of this group of nematodes, the study emphasized the need of updated descriptions from accurately identified specimens, isolation of sufficient material for examination, and molecular and phylogenetic analysis for a better understanding and diagnostics of Longidorid nematodes.

Description of Longidorus cheni sp. n. (Nematoda, Longidoridae) from China

Longidoruschenisp. n., an amphimictic species recovered from the rhizosphere of Larixprincipis-rupprechtii and Pyracanthafortuneana in Shanxi and Beijing, China, is described and illustrated. The taxonomic position of L.chenisp. n. among other species within the genus was elucidated using morphometric and molecular data, and phylogenetic relationships were inferred using D2–D3 expansion domains of 28S and 18S rRNA genes by Bayesian Inference (BI) method. The new species is characterised by females with a medium body size (L = 4.9–6.6 mm), a lip region slightly expanded, broadly rounded frontally and laterally, the amphidial fovea broad and symmetrically bilobed at base, odontostyle long and slender (143–168 μm), odonthophore slightly swollen at the base, tail short bluntly conoid to rounded. Guide ring located far posterior from the oral aperture (70–93 μm). Males with two ad-cloacal pairs of supplements preceded by a row of 10–14 ventromedian supplements, with robust spicules measuring 111–126 μm along the median line. Three juvenile stages were present, tail shape of J1 elongate conoid while in J2 and J3 the tail gradually becomes bluntly rounded. Codes for identifying the new species are: A6-B3-C5-D2-E2-F3-G1-H1-I2-J2-K2. Longidoruschenisp. n. belongs to a group of species with a guide ring at the mid-odontostyle position that have a predominantly Asiatic origin. It differs from all of them by a combination of morphological characters and unique sequences of partial 18S and D2–D3 region of 28S rRNA genes. The percentage dissimilarities in partial 18S and D2–D3 28S rRNA genes of L.cheni to the closest species (L.litchii, L.fangi, L.jonesi and L.juglans) were 1.5 %–1.8 % and 16.8–18.3 %, respectively.

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

Longidorus pinussp. 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 thatL. pinussp. n. is closely related toL. hangzhouensis,L. asiaticus, andL. camelliae, all of which apparently share a common Asiatic geographic origin. In addition, a key for identification ofLongidorusfound in China, based on morphological characters of both female and first-stage juvenile, is provided.