<I>Longidorus ferrisi</I> n. sp. from California Citrus

  • R. T. Robbins
  • Weimin Ye
  • Majid Pedram
Keywords: 18S rDNA, California, Citrus, DNA sequencing, Longidorus ferrisi n. sp., molecular phylogeny, morphology, needle nematode, new species, taxonomy


In October 1999, the authors received fixed specimens of a species of Longidorus from Howard Ferris found about the roots of a citrus tree in Oakville, Napa County, CA. After determining it to be new a species, we requested additional specimens. The samples contained roughly equal numbers of males and females. Longidorus ferrisi n. sp. is most similar to L. elongatus, but can be distinguished by a greater c-ratio (111-187 vs 73-141), a lesser c (0.7-1.1 vs 1.0-1.3), a more offset head, a more posterior guide ring (35-40 vs 30-33 mm), the presence of sperm in the uterus in mature females, and the approximate 1:1 ratio of females to males. Other similar species include L. artemisiae, L. crassus, L. glycines, and L. milanis. Longidorus ferrisi n. sp. differs from L. artemisiae by a lesser a-ratio (74-102 vs 109-155), a lesser c value (0.7-1.1 vs 1.0-1.6), a more posterior guide ring (35-40 vs 27-34 mm), a longer odontostyle (91-108 vs 84-98 mm), a wider lip region (16-19 vs 14-17 mm), wider mid-body (53-69 vs 41-52 mm), and longer spicules (57-65 vs 39-49 mm). The new species differs substantially from L. crassus by its lip shape and the presence of males, and differs from L. glycines by a shorter body (4.33-5.97 vs 6.14-8.31 mm), a lesser c value (0.7-1.1 vs 0.9-1.4), a narrower lip region (16-19 vs 20-23 mm), wider mid-body (53-69 vs 39-57 mm), longer spicules (53-69 vs 45-53 mm), and fewer supplements (7-11 vs 11-17). Longidorus ferrisi n. sp. differs from L. milanis by a longer body (4.33-5.97vs 3.00-4.90 mm), a greater c value (111-187 vs 86-130), a wider mid-body (53-69 vs 43-56 mm), a different head shape, and longer spicules (53-69 vs 41-54 mm). The nuclear 18S ribosomal DNA sequence of this species revealed that this species is unique with respect to all sequenced Longidorus species.