Weimin Ye

Morphological and molecular analysis of six aphelenchoidoids from Australian conifers and their relationship to Bursaphelenchus (Fuchs, 1937)

Six isolates of Australian Aphelenchoidoidea, viz., Laimaphelenchus preissii from native coniferous Callitris preissii trees, L. australis from the common pine plantation trees of Pinus radiata and P. pinaster and L. heidelbergi and two morphospecies of Aphelenchoides (H1 and K1) and Cryptaphelenchus sp. (K2) from diseased P. radiata trees, were studied using light microscopy, scanning electron microscopy and phylogenetic analyses of nearly full length sequences of SSU, D2/D3 expansion segments of LSU rDNA and a fragment of cytochrome oxidase subunit I (COI). Bayesian phylogenetic analyses of SSU, LSU and COI of the six nematode species revealed that none of these Australian aphelenchoidoids was inferred to be closely related to Bursaphelenchus. The selected isolates of Aphelenchoides and Laimaphelenchus used in this study were paraphyletic in all molecular analyses. Cryptaphelenchus sp. (K2) was inferred to be sister to Seinura with SSU sequences.

Oscheius carolinensis n. sp. (Nematoda: Rhabditidae), a potential entomopathogenic nematode from vermicompost.

Summary – Oscheius carolinensis n. sp. (Rhabditidae) was recovered through the Galleria bait method from vermicompost produced in Raleigh, NC, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit rDNA gene (SSU), D2/D3 expansion segments of the large subunit rDNA gene (LSU) and internal transcribed spacer (ITS), revealed this as a new species, described herein as Oscheius carolinensis n. sp. The new species is characterised by a combination of characters including its unique DNA sequences, amphimictic reproduction, six separate lips with bristle-like sensilla, lateral field with four lines, leptoderan and open male bursa, arrangement of bursal papillae 1 + 1 + 1/3 + 3 + ph, evenly spaced first, second and third papillae, and separate spicules that are distally shaped like a crochet needle. Oscheius carolinensis n. sp. belongs to the Insectivorus-group and is closest to O. colombianus, O. chongmingensis n. comb., O. insectivorus and O. lucianii. A Bacillus-like bacterium appears to be associated with this nematode, based on our microscopic and SEM observations. Exposed Galleria larvae were killed within 5 days and numerous nematodes were recovered from the cadavers within 48 h. Preliminary tests revealed that this nematode is capable of infecting at least two other insect species (Pieris rapae and Tenebrio molitor) under laboratory conditions and therefore has potential as a biological control agent. The status of Heterorhabditidoides chongmingensis is discussed, the genus is proposed as a junior synonym of Oscheius ,a ndO. chongmingensis n. comb. is proposed.

Phylogeography of Coptotermes gestroi and Coptotermes formosanus (Isoptera: Rhinotermitidae) in Taiwan.

ABSTRACT The Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is primarily reported from subtropical and warm temperate regions, whereas Coptotermes gestroi (Wasmann) is reported from many areas of the tropics. Taiwan is one of a few areas where the distributions of the two species overlap. By analyzing partial mitochondrial sequences of COII, 12S rRNA, and 16S rRNA, we found that most Taiwanese C. formosanus populations were closely related to Japanese and some Chinese populations and that Taiwanese C. gestroi populations were most closely related to those from the Philippines and Hawaii rather than populations from Thailand, Malaysia, Singapore, and Indonesia. The intraspecific variation of C. formosanus was 0.7–0.8% for three genes among seven Taiwanese populations, whereas all Taiwanese C. gestroi populations had identical sequences. The results support that Taiwan may be a center of origin for C. formosanus, but a recent introduction site for C. gestroi.

Identification of Chilean Reticulitermes (Isoptera: Rhinotermitidae) Inferred from Three Mitochondrial Gene DNA Sequences and Soldier Morphology

Abstract Results of Bayesian, maximum parsimony (MP), and neighbor joining (NJ) analysis of mitochondrial COII, 16S, and 12S gene DNA sequences and soldier morphology identified Chilean samples of a Reticulitermes species as the eastern subterranean termite, Reticulitermes flavipes (Kollar). All Chilean R. flavipes samples had identical gene sequences for all loci examined, suggesting a single geographic introduction. The combined DNA sequences for Reticulitermes santonensis Feytaud collected from France were almost identical to those of R. flavipes samples from Florida, which agreed with previous studies suggesting that R. santonensis is a junior synonym of R. flavipes. One unexpected finding was a R. flavipes sample collected from California that closely resembled the Chilean R. flavipes in their combined mitochondrial DNA sequences. We hypothesize that the Chilean R. flavipes may have been introduced from California or vice versa or that both Chilean and Californian R. flavipes may have the same origin in North America. Except for one sample from Florida (3% divergence), intraspecies variation of R. flavipes used in this study was <1%.

Two new species of Schistonchus (Nematoda: Aphelenchoididae) associated with Ficus hispida in China

Two new nematode species of the genus Schistonchus were recovered from syconia from a single Ficus hispida caprifig tree in Guangzhou, China. They are described herein as Schistonchus guangzhouensis n. sp. and S. centerae n. sp. Schistonchus guangzhouensis n. sp. is characterised by possessing the longest postuterine sac (PUS) of all currently described females in the genus (84-148 μm or >3.5 vulval body diam. (VBD) long), excretory pore situated near the level of the metacorpus, two pairs of subventral papillae on the male tail, and unique recurved and mitten-shaped spicules. Schistonchus centerae n. sp. is characterised by a unique fusiform tail tip and short PUS (8-20 μm or <1.0 VBD long) in reproductive females, excretory pore located near the head, spicules with an indistinct rostrum, male tail with three pairs of papillae, and broadly truncate tail tip. Both new species were easily differentiated from each other and other members of the genus for which sequences of the D2/D3 expansion segments of the large subunit rRNA gene (LSU) and partial small subunit rRNA gene (SSU) were available. Phylogenetic analysis also supported a monophyletic Schistonchus within a well-supported clade of Aphelenchoididae (sensu Hunt, 1993) and shared a most recent common ancestor with Aphelenchoides and Laimaphelenchus.

A review of the taxonomy, phylogeny, distribution and co-evolution of SchistonchusCobb, 1927 with proposal of Ficophagusn. gen. and Martinineman. gen. (Nematoda: Aphelenchoididae)

The purposes of this paper are to clarify the taxonomic status of the fig-pollinating wasp associate Schistonchus sensu lato(Nematoda: Aphelenchoididae) and to suggest directions for future research on the systematics, life history and ecology of the group. Molecular phylogenetic analyses suggest that Schistonchus s.l.is polyphyletic, and the composition of the three major clades is outlined, together with information on nematode morphology, plant host species, associated pollinating wasp species, and distribution. Biological information and collection data is presented for Schistonchus s.l.from Ficussycones (Moracea) in Africa, Australia, Asia and Central America, and its putative phylogeny is discussed based on molecular and morphological evidence. Both wasps and figs are millions of years old and have worldwide distribution in tropical areas, i.e., opportunities for Schistonchus s.l.-like nematodes to have evolved could have occurred more than once. In addition, figs and their pollinating wasps have variable life histories, which could have provided opportunities for Schistonchus s.l.to also develop different life histories. However, these histories occur inside fig sycones and in association with wasps, which has apparently led to evolutionary convergence and extreme morphological conservatism. Diagnostic characters and their states, derived from examination of described species and morphospecies of Schistonchus s.l.and informed by molecular phylogenetic inferences, are discussed and illustrated. Schistonchus sensu strictois redefined, and Ficophagusn. gen. and Martinineman. gen. are proposed. Schistonchus s.s.is morphologically characterised by having the excretory pore opening in the region of, or posterior to, the metacorpus; Ficophagusn. gen. by having the excretory pore opening very near the cephalic region; and Martinineman. gen. by having it opening at the anterior end of the metacorpus. Several species of Schistonchus s.s.have a labial disc, but there is no evidence of this in either Ficophagusn. gen. or Martinineman. gen.

Schistonchus (Aphelenchoididae) from Ficus (Moraceae) in Australia, with description of S. aculeata sp. n.

A checklist of Schistonchus collected from Ficus spp. in Australia and stored in the Waite Nematode Collection at the University of Adelaide is presented. Within Australia, Schistonchus contains 12 morphospecies and four nominal species, based on a combination of the following characters: body shape when heat-relaxed, position of excretory pore, length of post-uterine sac, spicule form, and number and position of caudal papillae. Up to four morphospecies of Schistonchus have been collected from one species of Ficus and, in several cases, one morphospecies of Schistonchus has been collected from more than one host fig species. A phylogenetic tree based on D2/D3 sequences showed that Australian collections of Schistonchus fall into two clades, suggestive of endemic and introduced lineages with host switching. Schistonchus aculeata sp. n. is described from F. aculeata and F. opposita and differentiated from other species of Schistonchus by having the excretory pore opening near the lips, a short post-uterine sac, rosethorn-shaped spicules, arcuate gubernaculum or thickening of dorsal wall, amoeboid sperm, and three pairs of caudal papillae (one pair adcloacal, one just posterior to mid-tail, and one near the tail tip), association with Kradibia spp. pollinating wasps and apparent biogeographical range. A key to the known species and morphospecies of Schistonchus from Australia is presented.

Teratodiplogaster fignewmani gen. nov., sp. nov. (Nematoda: Diplogastridae) from the Syconia of Ficus racemose in Australia

During the course of a survey of fig-associated nematodes in eastern Australia, we discovered an unusual diplogastrid nematode that we describe herein as Teratodiplogaster fignewmani gen. nov., sp. nov. This nematode was isolated as adults and juveniles from the syconia of Ficus racemosa in Queensland and Western Australia. It is presumed to be associated with the agaonid fig wasp, Ceratosolen fusciceps, for dispersion to new phase-B sycones. Teratodiplogaster fignewmani gen. nov., sp. nov. was inferred to be the sister taxon to the genus Parasitodiplogaster based upon molecular phylogeny using nearly full-length sequences of the SSU and D2/D3 LSU ribosomal RNA genes. It is sufficiently distinct in morphology (with many autapomorphies) to justify a new monotypic genus with the hypothesis that further species of Teratodiplogaster gen. nov. will be discovered when sycones from other Ficus from tropical Australasia and possibly Africa are sampled.

Acrostichus rhynchophori n. sp. (Rhabditida: Diplogastridae): a phoretic associate of Rhynchophorus cruentatus Fabricius and R. palmarum L. (Coleoptera: Curculionidae) in the Americas.

Acrostichus dauer larvae (JIII) were recovered during dissections of the palmetto weevil, Rhynchophorus cruentatus, from southern Florida, and the palm weevil, R. palmarum, from Colombia, Costa Rica and Trinidad. Based upon morphological and molecular studies, the four isolates are conspecific and are described herein as A. rhynchophori n. sp. Acrostichus rhynchophori n. sp. is characterised by narrow, flap-like dorsal tooth, female gonads not reflexed to the level of the vulva, male spicule and gubernaculum morphology, i.e., spicule with small and indistinct manubrium embedded in lamina/calomus complex, strong expansion just posterior to manubrium and smoothly curved and smoothly tapered lamina/calomus complex, and gubernaculum with claw-like anterior end in lateral view and three distal branches in ventral view. The new species is distinguished from A. superbus by morphology of the spicule and gubernaculum. Type specimens of four other Acrostichus species, originally described from bark beetles from North America, i.e., A. concolor, A. gubernatus, A. ponderosus and A. taedus, were re-examined and photo-documented.

Schistonchus virens sp. n. (Aphelenchoididae) and Parasitodiplogaster australis sp. n. (Diplogastridae) from Ficus virens (Moraceae) in Australia

A new species each of Schistonchus and Parasitodiplogaster were recovered from the sycones of Ficus virens from St Lucia, Brisbane, QLD, Australia. This is also the first record of Parasitodiplogaster from Australia. The species are described here as Schistonchus virens sp. n. and Parasitodiplogaster australis sp. n. Schistonchus virens sp. n. is differentiated from other species of the genus by a combination of morphological characters, including C-shaped females and males, excretory pore opening located near the head, a short post-vulval uterine sac, rose-thorn-shaped spicule, amoeboid sperm, no gubernaculum, three pairs of subventral papillae on the male tail, DNA sequence data; biogeographical range and host wasp and Ficus species affiliation. Parasitodiplogaster australis sp. n. is differentiated from all other species of the genus by having females with only one gonad, males with C-shaped spicules with an arcuate, slender gubernaculum, characteristic arrangement of the male caudal papillae and DNA sequence data. The generic diagnosis of Parasitodiplogaster is emended to include loss of a female gonad.