Xiphinema bernardi n. sp. (Nematoda: Longidoridae) from the Great Smoky Mountain National Park

Abstract

In October 1985 during a survey of fauna of the Great Smoky Mountains National Park, Ernest Bernard recovered a limited number of specimens of a non-described species of Xiphinema (Nematoda: Longidoridae) and sent them to the senior author. The species is distinct from other species by its large size and having Z-organs in the genital tract. During July 2006, Dr. Bernard's survey crew took samples in the area where the species was first found and was successful in finding it again. Without Dr. Bernard's efforts, this species could not have been described and thus the new species is named X. bernardi n. sp. in his honor. Several female and juvenile specimens of the new species were recovered in a sample from a mixed forest of maple, hemlock, and silverbell. It is distinct from all others in Xiphinema group 4 species (with Z-organs) by having a longer total stylet length, 259.8 to 284.2 μm vs < 253 μm for all other species in this group. Xiphinema bernardi n. sp. is distinctive because of its long body length (4.45 to 6.00 mm), tail shape, and c' ratio. Of the group 4 species, it most closely resembles X. phoenicis. Second, third and fourth stage juvenile descriptions and morphometrics are included. The polytomous key code for X. bernardi n. sp. is A4-B1-C6-D56-E56-F(4)5-G4-H2-I34-J5-K?-L1. Molecular approaches using the internal transcribed spacer 1 sequences of nuclear ribosomal DNA suggested that X. bakeri and X. diversicaudatum are the most closely related species from the species examined.

Keywords: DNA sequencing; ITS; Smoky Mountains National Park; Xiphinema bernardi n. sp; juveniles; molecular phylogeny; morphometrics; nematode; taxonomy.

Fig. 1

Holotype female of Xiphinema bernardi n. sp. A) Head region with entire stylet. B) Posterior esophagus base. C) Tail. D) Anterior Z-organ. E) Posterior Z-organ. F) Vulval region. Scale bars in each picture.

Fig. 2

Paratype females of Xiphinema bernardi n. sp. A-C) Head with entire stylet. D) Anterior genital region. E) Enlarged Z-organ region. F-H) Tail region different shapes.

Fig. 3

Paratype juveniles of Xiphinema bernardi n. sp. A) J2 head. B) J2 tail. C) J3 head. D) J3 tail. E) J4 head. F-G) J4 tails. Scale bars in each picture.

Fig. 4

Drawings of Xiphinema bernardi n. sp. paratype females A-G) and juveniles H-J). A) Female head region with entire stylet. B). Anterior genital tract. C). Entire female. D). Genital region showing Z-organ. E-G). Female tails. H) J2 tail. I). J3 tail. J). J4 tail.

Fig. 5

The 10001st Bayesian tree inferred from ITS1 under GTR+I+G model (lnL=14610.5918; freqA=0.2813; freqC=0.208; freqG=0.2529; freqT=0.2578; R(a)=1.0104; R(b)=3.6894; R(c)=1.3796; R(d)=0.793; R(e)=4.6468; R(f)=1; Pinva=0.1546; Shape=2.2294). Posterior probability values exceeding 50% are given on appropriate clades.