Morphological and Molecular Diversity among Pin Nematodes of the Genus Paratylenchus (Nematoda: Paratylenchidae) from Florida and Other Localities and Molecular Phylogeny of the Genus.

Pin nematodes (Paratylenchus spp.) are root parasites found worldwide. They have different life cycles and feeding habits and can damage a wide range of plants. A remarkable diversity of pin nematode species was found in soil samples from Florida and other states of the USA, Canada, and Spain. Using integrative taxonomy, two new species (Paratylenchus hawaiiensis sp. n. and P. roboris sp. n.), six valid species (Paratylenchulus acti, P. aquaticus, P. goldeni, P. paralatescens, P. minutus (=P. shenzhenensis syn. n.), and P. straeleni), and two undescribed species were identified from Florida; P. goldeni, P. hamatus, P. hamicaudatus, P. holdemani, and P. pedrami were found in California, P. minutus in Hawaii, P. goldeni in Oregon and Washington, and one new species, Paratylenchus borealis sp. n., in Alaska. Outside the USA, Paratylenchus projectus was detected in samples from Canada and Spain as well as P. holdemani and Paratylenchus sp. from Spain. The pin nematode species from Belgium and Russia identified in former studies as Paratylenchus sp. F was herein described as a new species with the name of P. borealis sp. n., using a population from Alaska. Previously reported molecular type A of P. aquaticus from Hawaii was reclassified as P. hawaiiensis sp. n., using a population from Florida. Paratylenchus roboris sp. n. from Florida has obese sedentary females with a stylet 63-71 µm long. The results of the molecular analysis of P. shenzhenensis from Florida and China indicated that it was conspecific with P. minutus from Hawaii and considered here as its junior synonym. New 26 D2-D3 expansion segments of 28S rRNA, 17 ITS rRNA, and 20 COI gene sequences were obtained in this study. Phylogenetic relationships of Paratylenchus are reconstructed using the D2-D3 of 28S rRNA, ITS rRNA, and COI gene sequences. Congruence of molecular and morphological evolution and species identification problems are discussed. Obese females were found in two major clades of Paratylenchus. The problem of reference materials is discussed, and it is proposed to make more efforts to collect topotype materials of known Paratylenchus species for molecular study.

Morphology, development stages, and phylogeny of the Rhabditolaimus ulmi (Nematoda: Diplogastridae), a phoront of the bark beetle Scolytus multistriatus from the elm Ulmus glabra Huds. in Northwest Russia.

The nematode Rhabditolaimus ulmi was found in galleries, adults, and larvae of Scolytus multistriatus, the vector of the Dutch elm disease, in St. Petersburg parks. This nematode co-occurred with Bursaphelenchus ulmophilus, which is another phoretic partner of S. multistriatus. Nematodes were cultured on the fungus Botryotinia fuckeliana in potato sugar agar (PA) and used for morphological analyses of adults, juveniles, eggs, and dauers. Nematode females showed a didelphic female genital tract rather than a monoprodelphic gonad as reported in the original description. Male bursa peloderan, caudal papillae include three preanal pairs and one precloacal unpaired papillae; seven postanal papilla pairs, among which one is pore-like and possibly the phasmid homolog, one subdorsal, and a pair of three closely situated posteriorly at bursa alae. The juvenile stages differ in size and structure of their sexual primordia. Sex of juveniles may be identified from the third stage. The dauer juvenile is a phoretic third juvenile stage (DJ3), which enters and remains localized in the buccal cavity of beetle adults and last-instar larvae and also under the elytra and in the ovipositor's cavity of pupae and imagoes. The first molt J1-J2 occurred inside the eggshell. Adult females laid eggs in early stages of embryonic development or containing molted J2. The propagative non-phoretic J2 inside the egg and J3 have a long and well-developed median bulb. The phoretic dauer DJ3 has a small spherical bulb like the J1 juvenile within the egg. In a sterile fungal culture, the nematodes feed on both mycelium and their unidentified ecto-symbiotic bacteria, located on nematode surface coat and multiplying in PA. Diagnosis and tabular key to the Rhabditolaimus species are given. Phylogenetic analysis of the D2-D3 of 28S rRNA gene sequences resulted in the Bayesian consensus tree with the highly supported clade of the Rhabditolaimus species.

Morphological and molecular characterization of Xiphinemella esseri Chitwood, 1957 (Dorylaimida: Leptonchidae) from Florida, with the first molecular study of the genus.

A population of Xiphinemella esseri, recently collected under the canopy of associated live oak trees in north Florida, was studied and described with an integrative approach, including the first molecular study of the genus. This Florida population is characterized by its 2.30 to 3.32 mm long body, labial disc well developed, lip region offset by constriction, and 16.5 to 17.5 µm broad, odontostyle 46 to 49 µm long with minute aperture, neck 288 to 296 µm long, pharyngeal expansion occupying 28 to 30% of total neck length, uterus a tripartite tube-like structure, pars refringens vaginae absent, vulva transverse (V = 45.4-49.7%), tail short and rounded (18-28 µm, c = 94-158, c' = 0.6-0.9), spicules 41 to 45 µm long, and 8 to 10 irregularly spaced ventromedian supplements bearing hiatus. The phylogenetic analysis inferred from the D2-D3 expansion segments of 28S rRNA gene and 18S rRNA gene sequences showed that X. esseri clustered with other dorylaims from the family Leptonchidae. A brief discussion about the distribution and biological considerations of X. esseri is also provided.

Morphological and Molecular Characterization of Kochinema farodai Baqri and Bohra, 2001 (Dorylaimida: Nordiidae) from California, with the First Molecular Study and an Updated Taxonomy of the Genus.

This paper deals with the morphological and molecular characterization of Kochinema farodai Baqri and Bohra, 2001, with an integrative approach. The finding of K. faroidai in California is a remarkable biogeographical novelty, as it is the first American record of the species. Molecular data herein obtained represent the first molecular study of the genus Kochinema. Furthermore, scanning electron microscopy (SEM) observations of a member of Kochinema are provided for the first time. Additionally, this contribution provides new insights into the phylogeny and taxonomy of the nematode genus Kochinema. A brief historical outline of the matter is presented. Then, the morphological pattern of the genus is revised and illustrated, the anterior position of amphids, whose opening is located on lateral lip, being its most relevant diagnostic feature. The phylogenetic analysis inferred from D2-D3 expansion segments of 28S rRNA gene shows that Kochinema clustered together with other dorylaimid species characterized by the absence of pars refringens vaginae and that it does not share a recent common ancestor with other members of the family Nordiidae. A likely polyphyly of the family Nordiidae is confirmed. Finally, an updated taxonomy of the genus is proposed, including a revised diagnosis, a list of species, a key to species identification, and a compendium of their main morphometrics and distribution data.

Morphological and Molecular Identification of Two Florida Populations of Foliar Nematodes (Aphelenchoides spp.) Isolated From Strawberry With the Description of Aphelenchoides pseudogoodeyi sp. n. (Nematoda: Aphelenchoididae) and Notes on Their Bionomics.

Two Florida populations of foliar nematodes were collected from strawberries originating from Cashiers, North Carolina (USA) located west from Willard, the type locality of Aphelenchoides besseyi. Both nematodes were cultured on Monilinia fructicola and identified using morphological characteristics and molecular assays as Aphelenchoides besseyi and Aphelenchoides pseudogoodeyi sp. n., a herein described new species related to Aphelenchoides goodeyi belonging to the Group of Aphelenchoides exhibiting stellate tails. The morphological and biological characters of Florida A. besseyi fit those of the original description of this species. A. pseudogoodeyi sp. n., which was initially misidentified as Aphelenchoides fujianensis, differed from the type population of the latter species from China because it was without males, and females lacked a functional spermatheca, whereas type A. fujianensis is an amphimictic species. Phylogenetic analyses using near full-length 18S ribosomal RNA (rRNA), the D2-D3 expansion fragments of 28S rRNA, and partial COI gene sequences indicated that A. besseyi is a species complex. A. pseudogoodeyi sp. n. grouped in different clades from those of the type A. fujianensis, instead merging with populations identified of 'A. fujianensis' from Brazil and other countries, suggesting that the latter are conspecific and incorrectly identified. The Florida A. besseyi infected strawberry and gerbera daisy, but not soybean and alfalfa. A. pseudogoodeyi sp. n. is mainly mycetophagous. Localized inoculation of 300 specimens applied with filter paper adhering to the blade of the soybean leaves resulted in nematode penetration into the mesophyll with subsequent development of lesions limited to the inoculated area of the blade.

Multigene phylogeny of root-knot nematodes and molecular characterization of Meloidogyne nataliei Golden, Rose & Bird, 1981 (Nematoda: Tylenchida).

The root-knot nematodes of the genus Meloidogyne are highly adapted, obligate plant parasites, consisting of nearly one hundred valid species, and are considered the most economically important group of plant-parasitic nematodes. Six Meloidogyne species: M. arenaria, M. hapla, M. incognita, M. microtyla, M. naasi and M. nataliei were previously reported in Michigan, USA. For this study, Meloidogyne nataliei was isolated from the grapevine Vitis labrusca from the type locality in Michigan, USA, and was characterized using isozyme analysis and ribosomal and mitochondrial gene sequences. No malate dehydrogenase activity was detected using macerate of one, five, six, seven or ten females of M. nataliei per well. However, one strong band (EST = S1; Rm: 27.4) of esterase activity was detected when using homogenates of ten egg-laying females per well. Phylogenetic analyses of sequences of the partial 18S ribosomal RNA, D2-D3 of 28S rRNA, internal transcribed spacer of rRNA, mitochondrial cytochrome oxidase subunit I genes and the cytochrome oxidase subunit II-16S rRNA intergeneric fragment from fifty-five valid Meloidogyne species and M. nataliei were conducted using Bayesian inference and maximum likelihood methods. From these results, we infer 11 distinct clades among studied species, with M. nataliei and M. indica composing a basal lineage. Seventy five percent of these species belong to seven clades within the Meloidogyne superclade. Characterization of these clades is provided and evolutionary trends within the root-knot nematodes are discussed.

Description of Aphelenchoides giblindavisi n. sp. (Nematoda: Aphelenchoididae), and Proposal for a New Combination.

One new and one known species of the genus Aphelenchoides from Iran are studied. Aphelenchoides giblindavisi n. sp. is mainly characterized by having five lines in the lateral fields at mid-body, and a single mucro with several tiny nodular protuberances, giving a warty appearance to it, as revealed by detailed scanning electron microscopic (SEM) studies. The new species is further characterized by having a body length of 546 to 795 µm in females and 523 to 679 µm in males, rounded lip region separated from the rest body by a shallow depression, 10 to 11 µm long stylet with small basal swellings, its conus shorter than the shaft ( m = 36-43), 52 to 69 µm long postvulval uterine sac (PUS), males with 16 to 18 µm long arcuate spicules, and three pairs of caudal papillae. The new species was morphologically compared with two species of the genus having five lines in the lateral fields namely A. paramonovi and A. shamimi and species having a warty-surfaced mucro at tail end and similar morphometric data ranges. The morphological features and morphometrics of the second studied species, A. helicus , agreed well with the data given for the type population. However, detailed study of fresh females revealed it has three drop-shaped stylet knobs and long PUS, making it typologically similar to the genus Robustodorus , meriting its taxonomic revision, i.e., transferring to it. In molecular phylogenetic analyses using partial small and large subunit ribosomal RNA gene (SSU and LSU rDNA) sequences, the new species formed a clade with A. heidelbergi in both SSU and LSU D2-D3 trees. The species A. helicus , however, clustered inside a well-supported clade of the genus Robustodorus in both trees, corroborating its newly proposed taxonomic placement as Robustodorus helicus n. comb.

Two rare species of tylenchids, Discotylenchus biannulatus n. sp. and Labrys chinensis Qing Bert, 2018 (Nematoda: Tylenchidae) from western Iran.

Two rare species of the family Tylenchidae are described and illustrated based on morphological and morphometric characters. Scanning electron microscope (SEM) studies provided details of anterior end structures, helpful in generic identification of the studied populations. Discotylenchus biannulatus n. sp. is characterized by its dorso-ventrally flattened smooth cephalic region having two proximal annuli and a rectangular perioral disc, short longitudinal amphidial slits, lateral field with four incisures, stylet 9-10 µm long, with the conus shorter than half the total stylet length and with posteriorly directed knobs, well-developed median bulb, mono-prodelphic reproductive system with rounded empty spermatheca and short postvulval uterine sac (PUS), and filiform tail with pointed end. It is compared with other species of Discotylenchus having four lines in the lateral field. The Iranian population of Labrys chinensis is characterized by its long and slender (a = 45.2-57.2) body, smooth rounded cephalic region and an offset disc-like apical labial plate, short longitudinal lateral amphidial slits, lateral field with two incisures, moderately developed stylet with the conus less than half the total length and posteriorly directed knobs, median bulb fusiform with distinct but weak valve, gradually joining the isthmus, vulva at 57.2-59.1% with small flaps, elongate conoid tail, uniformly and slightly narrowing toward end with broadly rounded terminus and rare males. The minor morphological differences of the recovered population with the type population are discussed.

Discopersicus n. gen., a New Member of the Family Tylenchidae Örley, 1880 with Detailed SEM Study on Two Known Species of the Genus Discotylenchus Siddiqi, 1980 (Nematoda; Tylenchidae) from Iran.

Discopersicus iranicus n. gen., n. comb., previously described from Iran as a new species under the genus Discotylenchus, is illustrated using light microscope and scanning electron microscope (SEM) observations and further studied using molecular characters. SEM studies revealed the newly proposed genus has oblique amphidial apertures on the lateral sides of the lip region. SEM images are also provided for two species of Discotylenchus, namely D. discretus and D. brevicaudatus, as the first SEM study of the genus. These results confirmed longitudinal amphidial aperture type on lateral sides of the lip region in genus Discotylenchus, as noted by Siddiqi while erecting the genus with D. discretus as the type species. Molecular phylogenetic analyses using partial small subunit (SSU) and large subunit (LSU) rDNA sequences revealed the affinity of the genus Discopersicus n. gen. with members of the subfamily Boleodorinae, as supported by morphological characters (mainly, the oblique amphidial opening).

Sectonema caobangense sp. n. from Vietnam (Nematoda, Dorylaimida, Aporcelaimidae).

Sectonema caobangense sp. n. from evergreen forest soil in Vietnam is described, including scanning electron micrograph (SEM) observations and D2-D3 LSU rDNA analysis. The new species is characterized by its 3.12 to 5.80 mm long body, lip region offset by deep constriction and 21 to 23 µm broad, mural tooth 13 to 14 µm long at its ventral side, 940 to 1,112 µm long neck, pharyngeal expansion occupying 61% to 69% of total neck length, uterus a long simple tube-like structure 292 to 363 µm long or 2.7 to 2.9 times the corresponding body diameter, pars refringens vaginae well developed, V = 48 to 56, short (36-51 µm, c = 77-132, c' = 0.5-0.8) and rounded tail, 87 to 99 µm long spicules, and four or five irregularly spaced ventromedian supplements bearing hiatus. Sectonema caobangense sp. n. differs from the typical pattern of Sectonema in the nature of the stomatal protrusible structure, bearing a mural tooth attached to the ventral side of the stoma. Molecular data obtained and the derived evolutionary trees support a close phylogenetic relationship with other Sectonema species.

Rotylenchus sardashtensis n. sp., a monosexual species from Iran, with molecular identification and detailed morphological observations on an Iranian population of Rotylenchus cypriensis Antoniou, 1980 (Nematoda: Rhabditida: Hoplolaimidae).

Rotylenchus sardashtensis n. sp., a new monosexual species is described and illustrated based on morphological, morphometric and molecular studies. Rotylenchus sardashtensis n. sp. appears close morphologically and molecularly to eight known species of the genus, i.e. R. buxophilus Golden, 1956, R. eximius Siddiqi, 1964, R. breviglans Sher, 1965, R. cypriensis Antoniou, 1980, R. pakistanensis Maqbool & Shahina, 1986, R. vitis Cantalapiedra-Navarrete, Liébanas, Archidona-Yuste, Palomares-Rius & Castillo, 2012, R. paravitis Cantalapiedra-Navarrete, Navas-Cortés, Liébanas, Vovlas, Subbotin, Palomares-Rius & Castillo, 2013 and R. dalikhaniensis Aliramaji, Pourjam, Álvarez-Ortega, Pedram & Atighi, 2015 from which the morphological differences are discussed. The new species is characterised mainly in having a hemispherical and well set off lip region with 3-4 annuli under light microscopy and irregular cob-like appearance under scanning electron microscopy (SEM), a stylet 26-30 µm long, a vulva located at 61-77% of body length with double epiptygma, rounded tail with 2-4 annuli and ventral mucron at its tip. Morphologically, R. sardashtensis n. sp. could be distinguished from all similar species within the genus by its matrix code as follows: A3, B1, C1, D4, E1, F2, G2, H5, I2, J2, K1. Rotylenchus cypriensis collected from the rhizosphere of Prunus sp. in Gilangharb region is characterised with its morphological and molecular data. Phylogenetic analyses based on sequences of the D2-D3 expansion region of the 28S rRNA gene and the ITS1 fragment revealed the relationships of both species examined in present study and other species of the genus Rotylenchus Filipjev, 1936 and the family Hoplolaimidae Filipjev, 1934 included in analyses.

Molecular and morphological characterization of Veleshkinema iranicum n. gen., n. sp. (Nematoda: Hexatylina, Sphaerularioidea) from Iran.

Veleshkinema  iranicum n. gen., n. sp. is described and illustrated based on morphological, morphometric and molecular characters. The new genus is characterized by having slender females and males, stylet with asymmetrical knobs, dorsal gland orifice just posterior to subventral knob, lip region with flattened apex and eight sectors, pharynx with a non-muscular and non-valvular median bulb, pharyngeal glands slightly overlapping intestine dorsally, visible cellular cardia, female with a single gonad having a quadricolumellate crustaformeria with 8-10 cells in each column, no postvulval uterine sac and rounded and offset spermatheca containing spheroid sperm cells, males with arcuate tylenchoid spicules and subterminal bursa. The new genus is morphologically compared with four genera: Abursanema, Deladenus, Prothallonema and Sphaerularia. Molecular phylogenetic studies of the new genus using 808 bp partial sequences of SSU ribosomal RNA gene placed the new genus in a clade with Sphaerularia spp. In phylogenetic analyses using 756 bp partial sequences of the 28S ribosomal RNA gene (D2-D3 segments), the new genus formed a monophyletic group with Abursanema iranicum and Sphaerularia spp.

Description of Trischistoma abharensis n. sp. (Nematoda: Trischistomatidae) and first record of Tripylella intermedia (Bütschli, 1873) Brzeski & Winiszewska-Slipinska, 1993 (Nematoda: Tripylidae) from Iran.

Two populations of the genera Trischistoma and Tripylella were recovered from the rhizosphere of grapevines and mosses growing on alder trees in Zanjan and Guilan provinces, respectively, Iran. The nematodes were identified as Trischistoma abharensis n. sp. and Tripylella intermedia, respectively. Trischistoma abharensis n. sp. is characterized by having females with body length 1069-1322 µm, presence of sparse somatic setae on the sublateral body, absence of ventromedian cervical setae, a distinct dorsal tooth directed anteriorly, absence of post-vulval uterine sac, and tail with one pair of subdorsal caudal setae. Males were not found. Tripylella intermedia is characterised by having females with body length 905-990 µm, annulated cuticle, stoma with two chambers: with dorsal tooth lying in posterior buccal chamber, and one large subventral and one small subventral tooth, respectively lying in posterior and anterior buccal chambers, cardiac glands large, composed of six fused cells, and tail 121-155 µm long, ventrally bent, anterior half broad, then suddenly narrowing, with posterior half tapered narrowly and cylindrically. The phylogenetic relationships of both species were analysed using sequences of the partial small subunit (SSU) and D2/D3 expansion segments of large subunit (partial LSU) of ribosomal RNA genes and are discussed.

Three new species of the genus Aporcelaimoides Heyns, 1965 from Vietnam (Nematoda, Dorylaimida, Aporcelaimidae), with an updated taxonomy of the genus.

Three new species of Aporcelaimoides from natural habitats in Vietnam are studied, described and illustrated, including line drawings, LM and/or SEM pictures. Aporcelaimoidesbrevistylum sp. n. is characterized by its body 1.95-2.90 mm long, lip region offset by deep constriction and 17-18 µm broad, ventral side of mural odontostyle 11-14 µm long with aperture occupying 62-71% of its length, neck 663-767 µm long, pharyngeal expansion occupying 58-66% of total neck length, uterus a simple tube 85-182 µm long, pars refringens vaginae absent, V = 55-63, tail short and rounded (34-46 µm, c = 49-76, c' = 0.6-0.8), spicules 67-86 µm long, and one ventromedian supplement out the range of spicules. Aporcelaimoidesminor sp. n. is distinguished in having body 2.09-2.61 mm long, lip region offset by deep constriction and 19-20 µm broad, mural odontostyle 14-16 µm long at its ventral side with aperture occupying 73-84% of its length, neck 579-649 µm long, pharyngeal expansion occupying 57-66% of total neck length, uterus a simple tube 44-69 µm long, pars refringens vaginae well developed, V = 48-56, female tail very short, rounded conoid or truncate (14-26 µm, c = 90-146, c' = 0.3-0.6), and male unknown. Aporcelaimoidessilvaticum sp. n. is characterized by its body 2.09-2.60 mm long, lip region offset by depression and 17-18 µm broad, mural odontostyle 11-12 µm long at its ventral side with aperture occupying 60-66% of its length, neck 597-720 µm long, pharyngeal expansion occupying 58-64% of total neck length, uterus a simple tube 128-243 µm long, pars refringens vaginae well developed, V = 58-60, tail short and rounded (27-37 µm, c = 67-94, c' = 0.6-0.7), spicules 64-75 µm long, and two or three widely spaced ventromedian supplements bearing hiatus. The genus Aporcelaimoides is restored, its diagnosis emended, and three species of Sectonema, namely Sectonemaamazonicum, Sectonemahaguei and Sectonemamoderatum, transferred to it. An updated list of its species, a key to their identification and a tabular compendium with the most important morphometric features are also presented.

Description of Sectonema septentrionale sp. n. (Nematoda: Dorylaimida: Aporcelaimidae) from Northern Iberian Peninsula.

A new species of the genus Sectonema, collected from natural forests in the Spanish provinces of León and Palencia, is described and illustrated with line drawings and LM pictures. Sectonema septentrionale sp. n. is characterized by its 5.59-6.90 mm long body, lip region 25-29 µm broad and offset by deep constriction, mural tooth 18-19 µm long at its ventral side and occupying most of the stomatal lumen, pharyngeal expansion 618-926 µm long or 60-73% of total neck length, uterus tripartite and 370-493 µm long or 2.9-4.3 times the corresponding body diameter, V = 48-52, tail short and rounded (40-62 µm, c = 108-146, c' = 0.6-0.8), spicules 100-145 µm long, and 5-11 irregularly spaced ventromedian supplements with hiatus. It is very close to S. demani, but differs both in the nature of the mural tooth and of the uterus.

Studies on the genus Aporcelaimellus Heyns, 1965 (Nematoda, Dorylaimida, Aporcelaimidae). Four atypical species with simple uterus from Southern Iberian Peninsula.

Three new and one known species of the genus Aporcelaimellus, collected mainly in natural areas from the Iberian Peninsula and characterized by having a simple uterus and atypical caudal region are described and illustrated, including line drawings, LM pictures and/or SEM pictures. Aporcelaimellus deserticola sp. n. is distinguished by its body 1.79-2.43 mm long, lip region 14-16 pm broad and offset by expansion rather than by constriction, odontostyle 18-21 µm long, neck 464-555 µm long, pharyngeal expansion 234-283 µm long or 49-52% of total neck length, a dorsal cell mass present at level of anterior end of intestine, uterus 34-67 µm long or 0.6-1.1 times the corresponding body diameter, V= 49-55, tail conical with rounded terminus (29-43 µm, c = 47-66, c' = 0.9-1.4) and bearing a short but perceptible hyaline portion, and male unknown. Aporcelaimellus hyalinus sp. n. is characterized by its body 1.49-2.23 mm long, lip region offset by constriction and 13-16 µm broad, odontostyle 14-16 µm long, neck 389-474 µm long, pharyngeal expansion 183-242 µm long or 45-53% of total neck length, uterus 44-106 µm long or 0.7-1.8 times the corresponding body diameter, V = 48-55, tail conical with rounded terminus (27-41 µm, c = 38-68, c' = 1.0-1.4) and short inner core, spicules 56 µm long, and seven irregularly spaced ventromedian supplements. Aporcelaimellus rarus sp. n. is distinguished by its body 1.96-2.34 mm long, lip region offset by constriction and 14-16 µm broad, odontostyle 15-16 µm long, neck 411-518 µm long, pharyngeal expansion 196-270 µm long or 48-52% of total neck length, a dorsal cellular mass at a short distance behind the cardia, uterus 63-96 µm long or 0.8-1.5 times the corresponding body diameter, V= 51-56, female tail short and conical (28-40 µm, c = 50-74, c' = 0.7-0.9) with rounded terminus and bearing a dorsal concavity at its posterior half, and males unknown. New data are provided for A. salicinus. A discussion of these atypical species is also provided.

Taxonomy of the genus Aporcelaimellus Heyns, 1965 (Nematoda, Dorylaimida, Aporcelaimidae).

The taxonomy of the genus Aporcelaimellus is revised and updated. A new definition is proposed, with several remarkable diagnostic characters: cuticle three-layered, especially distinguishable at caudal region, usually bearing a hyaline space between inner and intermediate layers at terminal portion of tail; cervical lacunae often present and well developed; oral aperture a dorso-ventral, hexagonal open slit; lip region showing bilateral symmetry and offset by a more or less distinct constriction; odontostyle short, robust and with wide aperture; uterus simple, bi- or tripartite; pars refringens vaginae present, well developed; tail similar in both sexes, short, rounded to conical with more or less rounded terminus; and ventromedian supplements 7-25 in number, separated, almost always with precloacal space (hiatus). A list of 28 valid species and their synonyms is provided as well as a key to their identification and a tabular compendium of their morphometrics. Aporcelainiellus faridpuriensis is considered to be a species inquirenda. Twenty-one species are regarded as incertae sedis: A. amplexor, A. budauniensis, A. canis, A. digicaudatus, Dorylaimus domus glauci, A. estonicus, A. gerlachi, A. goldeni, A. index, A. jairajpurii, A. monodelphus, A. nawabganjense, A. nivalis, A. paracentrocercus, A. paraobtusicaudatus, A. radicus,A. sacchari, A. seinhorsti, A. stilus, A. submissus and A. subsimilis. Two species are retained under other genera: A. bicuticulus under Labronema, and A. cocophilus under Aporcelaimus. Sixteen species are transferred to other genera: A. baqrii and A. odhneri to Crassolabium; A. dubius to Discolaimium as Discolaimium geraldi nom. n.; A. duhouxi to Labronema; A. glandus, A. heynsi, A. maitai and A. paraconicaudatus to Discolaimiun; A. insularis, A. jiaonanensis, A. kikereensis and A. propinquus to Aporcelinus; A. maximus to Aporcella; A. paracentrocercus apud Andrássy (1960) to Aporcelinus as Aporcelinus africanus sp. n.; A. saprophilus to Eudorylaimus; and A. tritici to Makatinus. Finally, A. concavus becomes a non-valid binomen.

Studies on the genus Aporcelaimellus Heyns, 1965 (Nematoda, Dorylaimida, Aporcelaimidae). Four typical species with simple uterus from Southern Iberian Peninsula.

Three new and one known species of the genus Aporcelaimellus with simple uterus and typical caudal region, mainly col-lected in natural areas of southeastern Iberian Peninsula, are studied, including descriptions, measurements, line illustrations and LM pictures. Aporcelaimellus baeticus sp. n. is characterized by a body length of 1.96-2.95 mm, lip region offset by constriction and 17-20 µm broad, odontostyle 17-22 µm long, neck 510-635 µm long, pharyngeal expansion 250-335 µm long, a dorsal cell mass at level of anterior end of intestine, uterus 60-150 µm long or 0.9-1.7 times the corresponding body diameter, vulva transverse (V = 48-54), tail convex conoid with broadly rounded terminus (30-46 µm, c = 47-80, c' = 0.7-1.1), spicules 99-103 µm long, and 18-21 irregularly spaced ventromedian supplements which lack hiatus. Aporcelaimellus brevicaudatus sp. n. is characterized by a body length of 1.54-2.14 mm long, lip region offset by a more or less distinct constriction and 14-16 µm broad, odontostyle 13-15 µm long, neck 512 µm long, pharyngeal expansion 255 µm long, uterus 39-57 µm long or 0.9-1.0 times the corresponding body diameter, V = 50-55, tail short and rounded to hemispherical (24-27 µm, c = 66-82, c' = 0.6-0.7) with inner core hardly reaching the middle of tail length, and male unknown. Aporcelaimellus rotundus sp. n. is characterized by its body 2.01-2.58 mm long, lip region offset by constriction and 19-20 µm broad, odontostyle 22-23 µm long, neck 455-579 µm long, pharyngeal expansion 226-316 µm long, a dis-tinct dorsal cell mass present at cardia level, uterus 28-74 µm long or 0.5-0.9 times the corresponding body diameter, V = 47-52, female tail short and conoid to rounded (27-33 µm, c = 64-90, c' = 0.7-0.9), and males unknown. New data, including SEM pictures, sequences and taxonomic comments, are provided for A. waenga.