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  • Author or Editor: Robin Giblin-Davis x

Weimin Ye, Yongsan Zeng and Robin Giblin-Davis

Abstract

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.

Walter Sudhaus, Robin Giblin-Davis and Karin Kiontke

Abstract

Caenorhabditis angaria n. sp., an ectophoretic associate of the West Indian sugarcane weevil, Metamasius hemipterus (Coleoptera: Curculionidae) is described and illustrated. Data on biology (longevity, fecundity) and ecology are presented. Caenorhabditis angaria n. sp. is gonochoristic and can be differentiated from other species of Caenorhabditis by its comparatively short stoma in combination with six semicircular overlapping flaps on the lips, lack of a pharyngeal sleeve, one pair of teeth on each sector of the metastegostom, and a proximally open bursa with nine pairs of genital papillae (GP) and papilliform phasmids (ph) in a 2/2 + 2 + 3 + ph arrangement with GP4 and 7 opening dorsally. Caenorhabditis angaria n. sp. was isolated and cultured from M. hemipterus from Dade, Broward and Palm Beach Counties, FL, USA, and from Port-of-Spain, Trinidad, and from the American palm weevil, Rhynchophorus palmarum, from Trinidad. The nematode is phoretically associated with weevils as dauer juveniles without causing obvious deleterious effects. Caenorhabditis angaria n. sp. does not require the association with a weevil and can be cultured continuously on bacteria.

Barbara Center, Robin Giblin-Davis and Natsumi Kanzaki

Abstract

The type specimens of four Bursaphelenchus species described by Massey, i.e., B. tritrunculus, B. willi, B. scolyti and B. maxbassiensis, were re-examined and photo-documented to update the descriptions in the light of a contemporary understanding of the genus. Detailed spicule morphology, lateral field (probably with two lines), hemizonid and a three-celled structure at the uterus-postuterine sac junction of females were observed for B. tritrunculus, all features not originally described. Based on spicule and vulval structure, B. tritrunculus is hypothesised to be related to the 'hunti' group of the genus. The type material of B. willi was in poor condition and several morphological features have been lost, although variation of excretory pore position and additional features of spicule morphology were observed and described. Bursaphelenchus willi is a morphologically atypical species within the genus. With only two pairs of male caudal papillae and an inconspicuous narrow 'bursa', it appears typologically similar to the Cryptaphelenchus lineage, although females have a functional rectum and anus. Re-isolation and molecular characterisation are needed to help define the precise status of this species. The spicule morphology of B. scolyti was different from the original description, the species being similar to several European species. Bursaphelenchus scolyti shares several morphological and biological characters with B. xerokarterus, i.e., spicule and female tail morphology and host (vector) insect. Re-isolation of B. xerokarterus and comparisons between it and B. scolyti are necessary to assess possible conspecificity. Three females and several juveniles of B. maxbassiensis were available for examination. It has unusual lip and stylet morphology and an anteriorly located excretory pore. The inconspicuous rectum and anus are similar to some other genera of aphelench. The precise phylogenetic position of B. maxbassiensis was not confirmed, partly because male specimens were not available. Re-isolation and wider comparisons involving molecular phylogenetic inferences, i.e., with other aphelench genera, are necessary.

Natsumi Kanzaki, Takuya Aikawa and Robin Giblin-Davis

Abstract

Bursaphelenchus tokyoensis n. sp. is described and figured from a dead Japanese red pine, Pinus densiflora. Despite several attempts, the new species was not successfully cultured and so individuals isolated from the original dead log were used as type specimens. The new species has a body length of ca 710 μm (male) and 770 μm (female), medium values of ratio a (ca 32-38 for males and ca 29-41 for females), b ratio of ca 10-12 (male) and 11-14 (female), c ratio of ca 24-29 (male) and 30-41 (female), c′ ratio of ca 2.3 (male) and ca 2.0 (female), ca 11-14 μm long stylet, four lines in the lateral field, relatively small (ca 14-16 μm), smoothly arcuate spicule lacking clear condylus, rostrum and cucullus, seven male caudal papillae and short and broad female tail with variable-shaped terminus. The new species is typologically close to B. idius but can be distinguished by male caudal papillae arrangement, female tail length and number of lateral lines. Inferred trees based upon molecular phylogenetic analysis of near full length (ca 1.6 kb) small subunit and ca 0.7 kb of the D2/D3 expansion segment of the large subunit of ribosomal DNA placed B. tokyoensis n. sp. closest to the xylophilus- and africanus-groups. However, the new species is distinguished from members of these groups by its characteristic spicule morphology and relative molecular phylogenetic placement.

Natsumi Kanzaki, Robin Giblin-Davis and Barbara Center

Abstract

Ektaphelenchoides spondylis n. sp. is described and figured from Spondylis buprestoides. The new species is characterised by the bipartite stylet conus, male spicule with rounded condylus, blunt rostrum and plate-like cucullus, long postuterine sac and long and smoothly tapering female tail. The new species is almost morphologically identical to E. compsi, but can be distinguished from it by stylet morphology, female tail shape, male ratio (a) and molecular sequence of the D2/D3 expansion segment of the large subunit of ribosomal DNA. In the molecular phylogenetic analysis, E. spondylis n. sp. formed a well supported clade with E. compsi within Ektaphelenchoides. Based upon molecular phylogenetic analysis with one locus, Ektaphelenchoides spp. formed a well supported clade and Ektaphelenchus and Cryptaphelenchus also formed a well supported clade. However, the molecular and morphological information available from our study are insufficient to revise the generic taxonomy of the subfamily. More sampling and an integrated taxonomic revision of the subfamily Ektaphelenchinae are needed.

Natsumi Kanzaki and Robin M. Giblin-Davis

Rhabditidoides humicolus n. sp. is described and illustrated from arthropods associated with decaying tissue from the crown shaft of a living spindle palm, Hyophorbe verschaffeltii, in southern Florida, USA. In addition to its generic character, i.e., the arrangement of male genital papillae, ⟨v1, v2, v3d, CO, v4, (ad, v5, ph, v6), (pd, v7)⟩, the new species is characterised by its small stomatal flaps, a secretory pore-like opening, a pair of deirids, two pairs of post-deirids and small subventral vulval papillae located just anterior to the vulva. Besides those newly found characters, there are only a few typological differences between R. humicolus n. sp. and several previously described species in the genus. However, based on the biological characters, e.g., gonochoristic reproduction, association as dauers with the crane fly, Limonia (Rhipidia) schwarzi (Diptera: Limoniidae), millipedes, an immature cockroach, and staphylinid beetle adults, and distribution in southern Florida, the new species was considered to be different from others in the genus.

Natsumi Kanzaki and Robin M. Giblin-Davis

Summary

A new Acrostichus species is described based upon molecular sequence profiles and hybridisation testing. The new species, A. palmarum n. sp., had been previously described as local isolates (strains) of A. rhynchophori, i.e., an isolate recovered from Rhynchophorus cruentatus from South Florida (culture code RGD193) was designated as the type strain of A. rhynchophori, and other Central and South American strains (RGD194-196), recovered from R. palmarum were considered as conspecific regional isolates. However, additional sequencing of ribosomal DNA loci (near full-length of small subunit, full length of internal transcribed spacer and D2-D3 expansion segments of large subunit) and partial mitochondrial cytochrome oxidase subunit I gene and hybridisation testing suggested the independent species status of RGD194-196. Furthermore, two strains of A. palmarum n. sp., RGD194 and RGD195, showed partial reproductive isolation from each other, i.e., the fecundity of F1 progeny was obviously low, suggesting that geographical isolation within a widely-distributed species is occurring.

Natsumi Kanzaki, Natsumi Kanzaki, Robin M. Giblin-Davis, Natsumi Kanzaki, Robin M. Giblin-Davis, Daniel Carrillo, Natsumi Kanzaki, Robin M. Giblin-Davis, Daniel Carrillo, Rita Duncan, Natsumi Kanzaki, Robin M. Giblin-Davis, Daniel Carrillo, Rita Duncan and Rafael Gonzalez

During an experimental host-plant survey for the invasive redbay ambrosia beetle, Xyleborus glabratus, in Homestead, Florida, it and three native species of ambrosia beetle, Xyleborus affinis, X. volvulus and Xyleborinus gracilis were found to be associated with a Bursaphelenchus species. This nematode species, isolated from ambrosia beetles from the tribe Xyleborini, was cultured on Monilinia fructicola or Botryotinia fuckeliana for further study and was determined to be new to science and a putative sister species to B. kiyoharai because of two apomorphic characters in males, viz., possession of a tail spike vs the typical bursal flap, and the apparent absence of the P1 ventral single papilla, both typically plesiomorphic characters for the genus. Additionally, B. kiyoharai is associated with X. serriatus suggesting that the host and microbiome associations that are shared between these two species, both of which are carried by ambrosia beetles, may have ecological and biological significance in their evolution and lineage radiation. Molecular phylogenetic analyses of the near-full-length small subunit (SSU: 18S) and the D2/D3 expansion segments of the large subunit (LSU: 28S) confirmed that B. penai n. sp. is very closely related to B. kiyoharai which is a member of the B. fungivorus clade that includes B. thailandae and B. willibaldi. Bursaphelenchus penai n. sp. and B. kiyoharai both share very similar overall spicule morphology with the B. fungivorus clade. The new species is described and can be typologically differentiated from B. kiyoharai by the position of the hemizonid and excretory pore and its different geographical and host associations.

Barbara Center, Robin Giblin-Davis, E. Allen Herre and Natsumi Kanzaki

Abstract

Parasitodiplogaster citrinema and P. popenema were re-isolated from syconia of Ficus citrifolia and F. popenoei, respectively, from Barro Colorado Island, Panama, and are redescribed and figured herein. Both of these species were previously described as having a “well-developed stoma” and in the case of P. popenema with “stoma slightly longer than wide”. Re-examination of fresh material revealed that they share characteristic stomatal morphology, i.e., relatively wide and tube-like stomas with newly observed thorn-like stegostomatal teeth. This is distinctive from the other described Parasitodiplogaster species, which either have a relatively short and narrow stoma with protuberant, claw-like, teeth or a simple cylinder. In addition to the characters of the male papillae arrangement and spicule and gubernaculum morphology, these two species are distinguished from each other by newly-observed lip morphology characters, viz., P. citrinema has three small setae on the outer surface of each lip sector whereas P. popenema has smooth lips. Both P. citrinema and P. popenema appear typologically closest to P. sycophilon, which has a relatively wide and open stoma and seven pairs of male genital papillae, but were distinguished from P. sycophilon by the presence of stegostomatal teeth and the arrangement of the genital papillae.