Anterior Genital Branch Research Articles

First report of Xiphinema hunaniense Wang & Wu, 1992 (Nematoda: Longidoridae) in Vietnam.

For the first time, a survey of plant-parasitic nematodes in the Central Highlands of Vietnam discovered a population of Xiphinema hunaniense Wang & Wu, 1992. The Vietnamese population of X. hunaniense is characterized by having an offset lip region, lack of anterior genital branch, vagina directed backward, and a digitate tail. Morphological features and morphometrics of this population are in agreement with the type population of X. hunaniense except for some variations. In addition, molecular characterization of this population and phylogenetic tree of 28S rDNA sequences of the genus are also provided.

Two new species of the genus Metaxonchium Coomans & Nair 1975 (Nematoda, Dorylaimida, Belondiridae) from Costa Rica, with new insights in the phylogeny of the family Belondiridae

Two new species of the genus Metaxonchium are described from natural habitats in Costa Rica. Metaxonchium parvisaccatum sp. n. is characterized by its 1.62–1.71 mm long body, lip region offset by constriction and 8.5–10 μm broad, odontostyle 10–11 μm long, neck 632–674 μm long, pharyngeal expansion occupying 68–71% of neck length, anterior genital branch reduced to a short uterine sac, 22–27 μm long or 1–2% of body length, posterior uterus long and tripartite without apophyses, vulva transverse (V = 54–55), caudal region short and rounded (23–26 μm, c = 62–76, c’ = 0.7–0.8), and male absent. Metaxonchium stenospiculum sp. n. is characterized by its 2.15–2.85 mm long body, lip region offset by constriction and 12.5–16 μm broad, odontostyle 13.5–16 μm long, neck 756–1011 μm long, pharyngeal expansion occupying 64–74% of neck length, anterior genital branch 8–13% of body length and consisting of a long uterine sac plus a terminal mass, posterior uterus long and tripartite without apophyses, vulva transverse (V = 53–59), caudal region short and rounded, nearly hemispheroid (20–28 μm, c = 91–126, c’ = 0.4–0.6) in females, and more conoid (29–41 μm, c = 80–88, c’ = 0.6–0.8) in males, spicules 96–102 μm long, and 11–14 spaced ventromedian supplements without hiatus. Molecular analysis of M. stenospiculum sp. n. D2-D3 LSU provides new insights in the phylogeny of Belondiridae as its rounded-tailed genera might constitute a monophyletic group.

Two new species of the genus Metaxonchium Coomans Nair, 1975 (Nematoda, Dorylaimida, Belondiridae) from Vietnam.

Two new species of the genus Metaxonchium are described from natural habitats of Vietnam. Metaxonchium bonkowskii sp. n. is characterized by its 1.69-2.23 mm long body, lip region offset by weak constriction and 9.5-10.5 µm broad, odontostyle 11-13 µm long, neck 673-868 µm long with the pharyngeal expansion occupying 66-77% of its length, anterior genital branch reduced to a uterine sac 75-135 µm long or 4-7% of body length, posterior uterus tetrapartite and including a Z-like differentiation, V = 51-55, and female tail short and rounded (37-51 µm, c = 66-97, c' = 0.5-0.7). Metaxonchium silvaticum sp. n is characterized by its 1.28-1.43 mm long body, lip region offset by weak depression and 7.0 µm broad, odontostyle 8-9 µm long, neck 502-630 µm long with the pharyngeal expansion occupying 65-76% of its length, anterior genital branch reduced to a uterine sac 65-80 µm long or 4-6% of body length, posterior uterus tripartite, non-echinophor, V = 52-57, tail short and rounded (18-23 µm, c = 56-74, c' = 0.6-0.8) with abundant blister-like or saccate bodies, spicules 41 µm long, and seven spaced ventromedian supplements.

A new dagger nematode, Xiphinema poasense n. sp. (Nematoda: Longidoridae), from Costa Rica

A new dagger nematode,Xiphinema poasensen. sp., is described and illustrated from three populations extracted from soil associated with a combined plantation ofEucalyptussp.,Cupressussp. andPennisetumsp. and wild plants from a tropical pre-montane forest in Costa Rica. The new dagger nematode is characterised by a moderate body size 2612 (2416-3042) μm long, a rounded lip region 15.0 (13.5-16.5) μm broad, separated from the body contour by a shallow depression, amphidial fovea large, stirrup-shaped, a very long odontostyle (175 (164-188) μm), stylet guiding ring located 167 (136-181) μm from anterior end, vulva situated anterior to mid-body (36-40%), anterior genital branch complete but strongly reduced, without uterine differentiation, female tail short, hemispherical to convex-conoid with a c′ ratio = 0.7 (0.6-0.8) and bearing two pairs of caudal pores, and male absent. Integrative diagnosis was completed with molecular data using D2-D3 expansion segments of 28S rRNA, ITS1 region, partial 18S-rRNA and the partial mitochondrial gene cytochrome c oxidase subunit 1 (coxI). The phylogenetic relationships based on D2-D3 segments of this species with otherXiphinemaspp. of theX.non-americanumgroup indicated thatX. poasensen. sp. clustered with other species with a reduced anterior genital branch from the morphospecies Group 2,viz.,X. costaricenseandX. krugi. However, the phylogeny ofcoxIand partial 18S rRNA gene revealed that the new species did not cluster withXiphinemaspecies having the anterior genital branch absent or reduced (i.e., morphospecies Groups 1 and 2, respectively).

Metaxonchium toroense n. sp. (Nematoda, Dorylaimida, Belondiridae) from Costa Rica, with the first molecular study of a representative of the genus.

The new species Metaxonchium toroense n. sp. from natural habitats of Costa Rica is described, including light microscopy (LM), scanning electron microscopy (SEM) and molecular (D2-D3 28S rDNA) analyses. The new species is characterized by its general size, the dimensions and appearance of its lip region, the length of the odontostyle and its fusiform aspect, the length of the neck and its pharyngeal expansion, the reduction of the anterior genital branch to a very short uterine sac without any rudiment of ovary or oviduct, tripartite and non-echinophor posterior uterus, the somewhat posterior vulva position, the length and shape of the caudal region, and the absence of males. Molecular analyses, the first to be performed on a Metaxonchium species, show a close relationship of the new species with representatives of the genera Axonchoides and Syncheilaxonchium.

Molecular and morphological characterization of Belondira coomansi n. sp. (Nematoda: Dorylaimida, Belondiridae) from Iran.

A new species belonging to the genus Belondira is described from natural areas in Iran. Belondira coomansi n. sp. is characterized by its general size, the dimensions and appearance of its lip region, presence of distinct labial and post-labial sclerotization, the length of the odontostyle and its inconspicuous lumen and aperture, the length of the neck and its pharyngeal expansion, the reduction of the female anterior genital branch to a simple uterine sac, a very short posterior uterus, the anterior position of the vulva, the length and shape of the caudal region with distinctly thick cuticle at its tip, the length of the spicules, and the presence of only one pair of ventromedian supplements. The new species is close to Belondira brevibulba, B. sacchari, B. tenuidens and B. thornei, and it is compared to them. Molecular characterization (D2-D3 expansion segments of the rRNA large subunit) of the new species is also provided, representing only the second species of this genus for which any DNA sequence data are available.

Description of a new species of the genus Caveonchus Siddiqi, 1982 (Nematoda: Dorylaimida) with diagnostic compendium and key to its species

Summary Caveonchus siddiqii n. sp. is described and illustrated based on specimens collected from both India and Japan. It is characterized by having a medium sized body (L= 0.86 - 1.12 mm); labial disc present; amphideal fovea flask-shaped; lip region cap-like, offset by slight constriction; odontostyle 8 - 9 μm, odontophore 10 - 12 μm; pharynx with slender anterior part which expands abruptly into the saccate basal bulb, occupying about 16 - 21 % of total neck length; female genital system mono-opisthodelphic; anterior genital branch 70 - 100 μm or 1.9 - 2.8 times the midbody diameter long; tail short, rounded, hemispheroid, 0.5 - 0.7 anal body diameter long; spicules 30 - 38 μm long; and three spaced ventromedian supplements. Its relationship with all the known species of the genus is discussed. A diagnostic compendium and a key to identification of the species is also provided.

Taxonomy of the genus Tantunema Siddiqi, 1982 (Dorylaimida: Tylencholaimidae) with description of one new and two known species

ABSTRACTOne new and two known species of the genus Tantunema Siddiqi, 1982 are described and illustrated. Tantunema indicum sp. nov. is characterized by having a small body (length 0.32–0.45 mm); lip region cap-like, set off by slight constriction; odontostyle 6–7 µm and odontophore 8–10 µm long; pharyngeal expansion gradual, expanded part occupying about 35–41% of total neck length, lumen of posterior expanded part widened and thickened; female genital system mono-opisthodelphic, anterior genital branch absent; tail short, hemispheroid, 0.8–1.1 anal body diameter long. Tantunema pakistanense (Timm, 1964) comb. nov. (=Tylencholaimus pakistanensis Timm, 1964) and Tantunema intermedium (Peña-Santiago and Coomans, 1996) Andrássy, 2009 are redescribed. A diagnostic compendium and key to species of the genus is also provided.

Free-living dorylaimid nematodes from nature reserves in Costa Rica. The genus Oriverutus Siddiqi, 1971 – species with simple uterus

AbstractThree Costa Rican species with a simple uterus, two new and one known, belonging to the genus Oriverutus are described. Descriptions, measurements and illustrations are provided. A detailed study of O. asaccatus, including SEM pictures, is presented and its diagnosis emended; O. sturhani is regarded as its junior synonym. Oriverutus costaricensis sp. n. is distinguished by its body 1.07-1.24 mm long, lip region offset by constriction and 14-15 μm broad, odontostyle 23.5-24 μm long, neck 277-353 μm long, pharyngeal-expansion 125-179 μm long or 45-51% of total neck length, cardia asymmetrical, a dorsal cell mass present at level of pharyngo-intestinal junction, female genital system amphidelphic, V = 45-48, tail conical and slightly bent dorsad at the end (42-43 μm long, c = 25-29, c′ = 1.7-1.8), and males unknown. Oriverutus hemihystera sp. n. is characterised by its body 0.92-1.17 mm long, lip region offset by shallow depression or almost continuous and 10-11.5 μm broad, odontostyle 22-24 μm long, neck 280-330 μm long, pharyngeal expansion 115-138 μm long or 41-43% of total neck length, female genital system amphidelphic but anterior genital branch reduced, V = 43-45, tail conical and slightly bent dorsad at the end (62-65 μm long, c = 15-18, c′ = 3.1-3.4), and males unknown.

Free-living dorylaimid nematodes from nature reserves in Costa Rica. The genus Oriverutus Siddiqi, 1971 – species with specialised uterus

Three Costa Rican species with a simple uterus, two new and one known, belonging to the genus Oriverutus are described. Descriptions, measurements and illustrations are provided. A detailed study of O. asaccatus, including SEM pictures, is presented and its diagnosis emended; O. sturhani is regarded as its junior synonym. Oriverutus costaricensis sp. n. is distinguished by its body 1.07-1.24 mm long, lip region offset by constriction and 14-15 μm broad, odontostyle 23.5-24 μm long, neck 277-353 μm long, pharyngeal-expansion 125-179 μm long or 45-51% of total neck length, cardia asymmetrical, a dorsal cell mass present at level of pharyngo-intestinal junction, female genital system amphidelphic, V = 45-48, tail conical and slightly bent dorsad at the end (42-43 μm long, c = 25-29, c′ = 1.7-1.8), and males unknown. Oriverutus hemihystera sp. n. is characterised by its body 0.92-1.17 mm long, lip region offset by shallow depression or almost continuous and 10-11.5 μm broad, odontostyle 22-24 μm long, neck 280-330 μm long, pharyngeal expansion 115-138 μm long or 41-43% of total neck length, female genital system amphidelphic but anterior genital branch reduced, V = 43-45, tail conical and slightly bent dorsad at the end (62-65 μm long, c = 15-18, c′ = 3.1-3.4), and males unknown.

Two New Species of the Genus Dorylaimoides Thorne & Swanger, 1936 (Nematoda: Dorylaimida) From Spain

Two new species belonging to the genus Dorylaimoides Thorne & Swanger, 1936 are described from natural areas in southeastern Spain, D. baeticus sp. n. is characterized by having lip region offset from the adjacent body, odontostyle shorter than head diameter, pharyngeal bulb marked off by a constriction, anterior genital branch reduced to a simple sac 1.7-3.5 times the corresponding body width long, tail conical with blunt terminus and five ventromedian supplements regularly spaced. D. cylindricaudatus sp. n. is distinguished by medium size (1.18-1.38 mm long), lips amalgamated with low inner part, pharyngeal bulb constricted, female genital system pseudo-opisthodelphic, tail cylindrical elongated 3.8-5 anal body widths long,and 5-6 regularly spaced ventromedian supplements.

Comments On the Taxonomy, Occurrence and Distribution of Longidoridae (Nematoda) in North America

The occurrence, distribution and associations with nepoviruses of members of the Longidoridae in North America are presented for each species. Three genera of Longidoridae, Longidorus (10 species), Paralongidorus (2 species), and Xiphinema (38 species) have been reported from North America. Twenty of the Xiphinema species are from the X. americanum group, twelve species have a conoid digitate tail, six species have a hemispherical tail with or without a peg, and two have a long conical tail. Seven North American Xiphinema species have a Z-differentiation and five have only one ovary. One species, X. krugi, has a normal posterior genital branch and ovary and a reduced anterior genital branch lacking an ovary. Longidorus diadecturus differs from all other North American Longidorus species in having weakly developed odontophore flanges and a guide-ring at about mid-odontostyle. Many of the species identifications require to be confirmed, especially those within the X. americanum-group. Five Xiphinema and one Longidorus species are natural vectors of nepoviruses in North America. It is suggested that methods routinely used in North American laboratories for extracting nematodes from soil are inappropriate for recovering Longidoridae and that these nematodes are more widespread and occur more frequently than indicated in published literature.

Description of Dolichodor Us Pellegrini Sp. N. (Nematoda: Dolichodoridae) and Xiphinema Fa Gesi Sp. N. (Nematoda: Dorylaimidae) From New Caledonia

New species of plant nematodes belonging to the genera Dolichodorus Cobb, 1914 and Xiphinema Cobb, 1913 are described and illustrated from New Caledonia. Dolichodorus pellegrini sp. n. differs from all known species of the genus in having a lateral field with one line. Of those species having the excretory pore at, or anterior to the medium bulb the other primary differential characters are: body, stylet and gubernaculum length. Xiphinema fagesi sp. n. is the sole monodelphic species having a spatulate posterior part. It differs further from other monodelphic species by having a short, more or less hemispherical tail without peg or bulge, by a greater body length, and by the structure of the anterior genital branch.

New and Known Nematode Species (Nematoda: Dorylaimida) From Romania

Four new and three known soil nematode species (Nematoda: Dorylaimida) from Romania were collected and examined. Chitwoodius retezatensis n. sp. has a body 1.33 (1.07-1.53) mm long, cap like lip region, odontostyle 24 (22.5-25) μm and odontophore 23 (21-26) μm long, a longitudinal vulva, and males with spicules 53 (50-57) μm long and a series of four-five ventro-median papillae. Funaria meri- dionalis n. sp. has a body 1.81 (1.49-1.97) mm long, slender odontostyle 7 μm long, longitudinal vulva surrounded by a cuticular membrane and a broadly conoid tail with a terminal mucro in the female; male with 42-45 μm long spicules and a series of five ventromedian supplements. Axonchium banaticum n. sp. is characterized by an amalgamated lip region not offset, vagina first slender and then thickened and lacking an anterior genital branch. A. bihariensis n. sp. has offset lip region with well separated rounded lips, very narrow antcrior oesophagus, oesophageal constriction inconspicuous, non-sclerotized vagina; anterior genital branch a simple sac, posterior genital branch with Z organ. Measurements, illustrations and comments are also given for three other known species, namely: Axonchium coronatum (de Man, 1906) Thorne & Swanger, 1936, Axonchium apud deconincki Nair, 1975 and Opisthodorylaimus sylphoides (Williams, 1959) Carbonell & Coomans, 1986. These species are all first records in the Romanian fauna.

Nine New Dorylaimida (Nematoda) From the New Zealand Region

The following species are described from either New Zealand pastures or peats on Chatham Island. Tylencholaimus chathami n. sp. is prodelphic, with short tail and without offset inner lip region; it is closest to T. dorae Kruger but differs in having V = 69-72% and c = 43-57. Tylencholaimus australis n. sp. has a hemispheroid tail and rudimentary posterior genital branch; it differs from T. maritus Loof & Jairajpuri in having V = 67-72% and in the posterior genital branch being two anal body widths long. Tylencholaimus rossi n. sp. in being opisthodelphic, less than 1 mm long and having a short tail is similar to T. pakistanensis Timm and T. gertii Kruger; it is differentiated by V = 54-58% and the tail being truncate. Tylencholaimus micronanus n. sp. is 0.38-0.42 mm long and is distinguished from T. nanus Thorne by its length and having c = 33-46 cf. 50-60. Dorylamioides chathami n. sp. has a rudimentary caudal gland duct, is pseudo-opisthodelphic with a distinctly offset lip region and may be distinguished from D. thornei (Jairajpuri) by being larger (L = 0.97-1-.38 mm), in the shape of the odontostyle and oesophageal bulb, and in having a rudimentary, reflexed anterior genital branch. Axonchium (Dactyluraxonchium) watti n. sp. is distinguished from A. (D.) arcuatum Thorne by being smaller, bisexual, and in having a well-developed prevulval sac. Axonchium (Discaxonchium) coxi n. sp. is distinguished from A. (D.) serpens Thorne, A. (D.) crassum Thorne, and A. (D.) micans Thorne by length, tail shape, and form of the vaginal sclerotisation. Oxydirus visseri n. sp. is opisthodelphic, has a more anterior vulva than O. oxycephalus and differs from O. tenuicaudatus in begin longer, bisexual, and in having a prevulval sac. Dorylaimellus pastura n. sp. is closest to D. andrassyi Heyns, but differs in being monosexual, larger, and in having over 70 glandular bodies in the lateral field.

The Genus Axonchium V. Species With Amalgamated Lip Region

The following Axonchium species belong to this group : A. amalgans Thorne, 1939, A. asacculum Siddiqi, 1968, A. baldum Thorne, 1964, A. indicum Siddiqi, 1964, A. nairi Altherr, 1974 and A. rotundum Thorne, 1964. These species have been redescribed on the basis of type material except for A. amalgans and A. baldum for which type specimens no longer exist. Two new species, A. coomansi from The Netherlands and A. deconincki from South Africa are described. A. coomansi n.sp. differs from all other species in the shape and structure of the vagina. It resembles A. rotundum and A. nairi from which it differs in the shape of the lip region and the tail and has shorter spicules. A. deconincki n.sp. differs from the other species in the structure of the vagina, the very small distal uterus expansion and the shape of the spicules. It resembles A. rotundatum, A. nairi and A. coomansi n.sp. from which it differs in tail shape and in having a simple sac-like anterior genital branch in females.