Sergio Álvarez-Ortega

New proposal for a detailed description of the dorylaim spicule (Nematoda: Dorylaimida)

The morphology of dorylaimid spicules is richer than usually conceived and shows interesting interspecific variations that have not received much attention. New ideas are proposed to describe these structures, including a delimitation or definition of their parts and a series of morphometrics, either (absolute) measurements or ratios. Three descriptive examples are presented. Several morphological characters (head shape, development of the ventral hump, etc.) and a number of morphometric features (total and relative lengths, relative size of the median piece, terminal tip width, etc.) are especially useful for species characterisation and comparative purposes.

Nematodes of the order Dorylaimida from Andalucía Oriental, Spain. Nevadanema nevadense gen. n., sp. n. (Qudsianematidae) from Sierra Nevada National Park

Nevadanema nevadense gen. n., sp. n. is described from natural highlands in the south-eastern Iberian Peninsula and is characterised on the basis of morphological, morphometric and molecular (D2/D3-LSU rDNA) data, including SEM study. The new genus is mainly distinguishable by its rounded and offset lip region with amalgamated lips, odontostyle comparatively attenuated, guiding ring double, odontophore rod-like, female genital system amphidelphic, pars refringens vaginae present, and short and rounded tail. It is morphologically close to Labronema, from which it differs in the nature of the lip region and odontostyle. Two species of Labronema, namely L. fimbriatum and L. uniforme, are transferred to the new genus.

Rotylenchus dalikhaniensis n. sp. (Nematoda: Hoplolaimidae), a monosexual species recovered from the rhizosphere of Ruscus hyrcanus Woronow in Mazandaran province, northern Iran

Summary – A new monosexual species of Rotylenchus is described and illustrated based on morphological, morphometric and molecular studies from northern Iran. Rotylenchus dalikhaniensis n. sp. is characterised by having a continuous, conoid lip region with four, rarely three, annuli, lateral fields regularly areolated in pharyngeal region and irregularly throughout the body except in tail region, rarely with anastomoses at mid-body, body without longitudinal striations, stylet 34-36 μm long, vulva located at 59-64%, tail with 16-19 annuli and ventral projection, and having no males in population. The differences of the new species with five known species, namely R. breviglans, R. alii, R. pakistanensis, R. echelimae and R. provincialis, are discussed. Phylogenetic analyses using 681 bp partial sequences of D2-D3 expansion region of the 28S and 383 bp ITS1-rRNA genes revealed that the new species formed a clade with some species of Helicotylenchus and Rotylenchus, respectively.

Morphological and molecular study of Californian species of the genus Aporcelaimellus Heyns, 1965 (Dorylaimida: Aporcelaimidae).

Several species of Aporcelaimellus collected in natural areas in California, USA, are characterised on the basis of morphological, morphometric and molecular data. Two new species are identified and described here. Aporcelaimellus californicus sp. n. is characterised by its body length of 2.46-3.42 mm, lip region offset by constriction and 24-26 μm broad, odontostyle 23-24 μm long, neck 611-765 μm long, pharyngeal expansion occupying 50-52% of total neck length, a dorsal cellular mass present at level of cardia, uterus simple and 246-408 μm long, V = 53-58, short conoid tail (43-50 μm, c = 56-71, c′ = 0.8-1.0) with a large hyaline portion occupying more than half of its total length, spicules 98 μm long, and 8-9 spaced ventromedian supplements. Aporcelaimellus salicinus sp. n. is distinguished by its body length of 1.45-1.94 mm, lip region offset by deep constriction and 16-18 μm broad, odontostyle 18-20 μm long, neck 393-521 μm long, pharyngeal expansion occupying 45-51% of total neck length, presence of a dorsal cellular mass at level of cardia, uterus simple and 21-45 μm long, V = 51-57, tail conical to conoid (31-38 μm, c = 39-59, c′ = 1.0-1.4), and male unknown. Measurements, sequences and taxonomic comments are provided for the other three Aporcelaimellus species. Californian Aporcelaimellus display a notable morphological homogeneity but a remarkable molecular diversity, putting into question the monophyly of this group.

An integrative approach to assess the phylogeny and the systematics of rounded-tailed genera of the subfamily Qudsianematinae (Nematoda, Dorylaimida)

The evolutionary relationships of rounded‐tailed dorylaimid genera traditionally classified under the subfamily Qudsianematinae in Qudsianematidae are analysed and discussed with an integrative approach, including morphological features, postembryonic development and D2–D3 expansion segments of 28S rDNA gene sequences. Evidences are provided that support a closer relationship of these genera with members of Dorylaimidae rather than with other representatives of Qudsianematidae. Specifically, remarkable are the changes observed in the morphology of caudal region (tail) during the postembryonic development, with a common pattern: the existence of one or more long‐tailed juvenile stages that result in short, rounded‐tailed adult stage. The new phylogeny derived from such evidences does not match the current classification system, and, consequently, several taxonomic changes are proposed to improve it: eight genera are transferred from Qudsianematidae to Dorylaimidae, the new subfamily Labronematinae is proposed to accommodate them, a new classification in presented for Dorylaimidae, and emended diagnoses are given for the family Dorylaimidae and the subfamily Qudsianematinae.

Morphological and molecular characterisation of Californian species of Metaporcelaimus Lordello, 1965 (Dorylaimida, Aporcelaimidae), with a new concept of the genus

Two new and one known species of Metaporcelaimus from Californian natural habitats were studied using morphological and molecular approaches. Metaporcelaimus marinensis sp. n. is characterised by its body 1.99-2.48 mm long, lip region offset by deep constriction and 14-15 μm broad, odontostyle 13-15 μm long, neck 456-529 μm long, pharyngeal expansion occupying 47-50% of total neck length, pharyngo-intestinal junction bearing a dorsal lobe, uterus tripartite and 201-262 μm long, pars refringens vaginae well developed, V = 55-58, tail conical (43-55 μm, c = 43-52, c′ = 1.3-1.6) with its inner core somewhat notched and nearly reaching the tip, spicules 54-63 μm long and 6-7 spaced ventromedian supplements located outside the range of the spicules. Metaporcelaimus ovogranulosus sp. n. is distinguished in having body 1.54-1.96 mm long, lip region offset by deep constriction and 17-19 μm broad, odontostyle 17-19 μm long, neck 415-539 μm long, pharyngeal occupying 49-53% of total neck length, uterus simple and 27-41 μm long, uterine eggs granulate, pars refringens vaginae well developed, V = 48-51, tail conical (35-44 μm, c = 39-52, c′ = 1.4-1.6) with its inner core notched and nearly reaching the tip, and male unknown. Measurements and LM illustrations are also provided for M. capitatus. Metaporcelaimus was morphologically compared with Aporcelaimellus. The analysis revealed that these genera are barely distinguishable from each other. Aporcelaimellus species can be separated into two groups, one of them being morphologically similar to Metaporcelaimus. Molecular data and the derived evolutionary tree show that Metaporcelaimus and Aporcelaimellus do not share a recent common ancestor. Consequently, a new concept is proposed for Metaporcelaimus, M. ahmadi sp. n. is proposed for A. coomansi apud Ahmad nec Baqri & Khera, and 16 species of Aporcelaimellus are transferred to Metaporcelaimus. An updated list of Metaporcelaimus species with their synonyms, a key to their identification and a tabular compendium with important taxonomic morphometric characters are given.

Morphological and molecular characterisation of Aporcelaimellus simplex (Thorne & Swanger, 1936) Loof & Coomans, 1970 and a new concept for Aporcella Andrássy, 2002 (Dorylaimida: Aporcelaimidae).

This contribution presents a study of Iberian and Californian populations of Aporcelaimellus simplex, including morphological, morphometric and molecular data. The species is characterised and distinguished by its lip region offset by an expansion, pars refringens vaginae absent, and conical tail with a small but distinct hyaline terminal portion. No significant difference exists between American and European populations. Molecular data and the derived evolutionary tree show a topology in which this species forms a well-supported group with members of Discolaiminae, far from other representatives of Aporcelaimellus. Putting special emphasis in the absence of pars refringens vaginae, A. simplex is transferred to the genus Aporcella. The taxonomy of this genus is revised in depth, with the proposal of an emended diagnosis, the provision of a list of 13 valid species (mostly new combinations from Aporcelaimellus) as well as a key to their identification and a compendium of their main morphometrics. Aporcella debruinae sp. n. is proposed for Aporcelaimellus papillatus apud de Bruin & Heyns, 1992.

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

Axonchoides smokyensis sp. n. (Dorylaimida: Belondiridae) from the Great Smoky Mountains National Park: the second species of a very rare genus

Axonchoides smokyensis sp. n., collected from a natural forest area in Tennessee, USA, is described and illustrated, including LM and SEM pictures as well as molecular (rRNA SSU-ITS1 and LSU D2/D3) sequences. The new species is characterised by its body length of 2.56-3.18 mm, lip region continuous and 10-12 μm wide, odontostyle 10-13 μm long, neck 662-789 μm long, anterior portion of pharynx enlarging gradually, pharyngeal expansion 407-548 μm long or 60-70% of the total neck length and surrounded by a strong muscular sheath with nearly longitudinal bands, female genital system pseudodidelphic-monodelphic with anterior branch lacking a functional ovary and posterior one bearing a long and tripartite uterus, V = 42-46, female tail slightly clavate (27-34 μm, c = 84-105, c′ = 0.8-1.0), male tail short and rounded (34-38 μm, c = 87-113, c′ = 0.7-0.9), spicules 49-53 μm long, and five or six widely spaced ventromedian supplements outside the range of the spicules. The taxonomy of Axonchoides is discussed on the base of morphological and molecular evidence, and an emended diagnosis proposed. It was easily differentiated from other sequenced dorylaimid taxa, but phylogenetic analysis from SSU and LSU failed satisfactorily to resolve its placement in Dorylaimina.

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

Abstract Three new species of Aporcelaimoides from natural habitats in Vietnam are studied, described and illustrated, including line drawings, LM and/or SEM pictures. Aporcelaimoides brevistylum 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. Aporcelaimoides minor 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. Aporcelaimoides silvaticum 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 Sectonema amazonicum, Sectonema haguei and Sectonema moderatum, 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.