Journal of Nematology 27(1):94-102. 1995. © The Society of Nematologists 1995. Amended Descriptions of Longidorus sylphus Thorne, 1939, L. crassus Thorne, 1974, and L. fragilis Thorne, 1974 (Nematoda: Longidoridae) 1 R. T. ROBBINS 2 AND D. J. F. BROWN 3 Abstract: Lectotypes are designated for Longidorus sylphus, L. crassus, and L, fragilis from Thorne's original specimens. Amended descriptions, tables of morphological means, ranges and standard deviations, photographs of the anterior, vulval, and tail regions, and diagnoses and relationships are provided for each of the three species to aid identification and to better determine phylogenetic relationships within the genus Longidorus. Key words: amended description, lectotype, Longidorus crassus, Longidorus fragilis, Longidorus sylphus, morphology, morphometric, nematode, paralectotype, systematics, taxonomy. During his distinguished career as a poorly known, is hardly distinguishable nematologist, Gerald Thorne described from closely related species." Outside three species of Longidorus: L. sylphus in North America, L. sylphus has been re- 1939 (16) and L. crassus and L. fragilis in ported from Korea (3), Hawaii, Iraq, India 1974 (17). The morphometric data pro- (1), and Bulgaria (4); however, these iden- vided with each description are less than is tifications have not been confirmed. Com- required by current standards. Each de- parison of Thorne's L. sylphus specimens scription included average values for body with nematodes from Iowa, identified by length, ratios a, b, and c, vulva as a per- the senior author as L. sylphus (10), re- centage of body length, and odontostyle vealed these latter specimens to represent length (stylet) but did not provide mor- a hitherto undescribed species. phometric ranges, standard deviations, Hooper (5) distinguished L. sylphus from and numbers of individuals examined. L. elongatus (de Man, 1876) Micoletzky, Odontophore length (extension) was given 1922 by its narrower head, shorter dis- for L. sylphus and L. crassus. In addition, tance from the oral aperture to the guide type specimens were not designated. ring, and more pointed, conical tail. Sev- These three species are indigenous to eral other authors, when describing new North America, but few records of their Longidorus species, have also distinguished occurrence have been published. Norton their species from L. sylphus. Longidorus dis- et al. (9) reported an extensive distribution tinctus Lamberti, Cholera & Agostinelli, of L. sylphus in North America but quali- 1983 differs by having a more expanded fied the report by stating "There is uncer- labial region and a much longer tail (8). tainty regarding some earlier identifi- Longidorus conicaudatus Khan, 1986 differs cations of this species. This can only be by the shape of the amphid and the size clarified through re-collection and reiden- and shape of the tail (7). Longidorus ishrati tification." The only confirmed reports of Javed, 1983 differs by having a longer od- these species are their descriptions (9,11). ontophore, larger a value, differently Sturhan (14) reported "L. sylphus, which is shaped amphids, and a more posteriorly located guide ring (6). Longidorus aetnaeus Roca, Lamberti, Agostinelli & Vinciguerra, Received for publication 25 April 1994. 1 Published with the approval of the Director of the Ar- 1986 differs by having a shorter body, kansas Agricultural Experiment Station. slightly shorter odontostyle, and smaller c 2 Professor, Department of Plant Pathology, Nematology Laboratory, University of Arkansas, Fayetteville, AR 72701. value (13). 3 Zoology Department, Scottish Crop Research Institute, The following Longidorus species differ Dundee, DD2 5DA, Scotland, UK. Research at the Scottish Crop Research Institute is grant-aided by the Scottish Office from L. crassus. Longidorus henanus Xu & Agricultural and Fisheries Department. Cheng, 1992 differs in having a shorter 94 Amended Descriptions of Longidorus: Robbins, Brown 95 odontostyle and a differently shaped lip SYSTEMATICS region (18). Longidorus arthensis Brown, Grunder, Hooper, Kingler & Kunz, 1994 Longidorus sylphus Thorne, 1939 differs in having a more rounded lip re- (Fig. 1; Table 1) gion, longer amphidial pouches, and com- monly found males (2). Longidorus iranicus Amended description Sturhan & Barooti, 1983, with a more Lectotype (female in glycerine): Amended rounded and obviously narrower lip re- morphometrics given in Table 1. gion (15), also differs from L. crassus. Paralectotypes: Four females and one juve- Currently, there are 98 putative species nile (J4): Amended morphometrics given in the genus Longidorus of which 58 have in Table 1. been described since 1974, when Thorne Female: Body forming J- to spiral-shape. described L. crassus and L. fragilis. This tax- Body width at odontophore base about onomic inflation in the number of Longi- 85% that at midbody, tapering to 25% at dorus species descriptions has caused con- lips. Cuticle containing inconspicuous fusion in identifying several of the earlier, pores, apparently plain and composed of inadequately described species. Further- two layers each about 1.5 p,m thick; subcu- more, difficulties with identification have ticle slightly thicker (up to 3 txm) in region been compounded by the paucity of reli- of odontostyle; thickened posterior region able characters useful for distinguishing starting about four tail lengths anterior to Longidorus species. the anus. Lip region slightly rounded an- We designate type specimens from the teriorly; small but conspicuous labial and nematodes available in Thorne's collection cephalic papillae present; body walls pos- for each of the three Longidorus species de- terior to papillae almost parallel one- scribed by Thorne. Also, supplementary eighth of distance to guide ring, then ta- morphometric data and photographs of pering; lip region not constricted or ex- the head, vulval, and tail regions are pro- panded. Amphidial pouches obscure, vided to aid identification and to better de- extending about 40 to 50% of anterior end termine the phylogenetic relationships to guide ring distance. Nerve ring about within the genus Longidorus. one body width posterior to odontophore ~ ~ ~iii~!~i~+~ ~i!!:! ~'~ i~'~# ~ • FIG. 1. PhotomicrographsofLongidorus sylphus Thorne 1938 females. A) Anterior region. B) Vulval region. C,D) Posterior region. Scale bar = 50 trm. i, 96 Journal of Nematology, Volume 27, No. 1, March 1995 TABLE 1. Morphometricst of five Longidorus sylphus Thorne, 1939, females and one juvenile from Thorne's collection (Timp. Loop, Utah). Paralectotypes (n = 4) Juvenile From Thorne Character Lectotype Mean Range 04) (n = 1) (16) Measurements (Ixm) Length Body 3,841 4,130 (4,087-4,203) 2,984 4,400 Odontostyle 75 76.7 (72-80) 62 ca. 85 Odontophore 53 46.7 (44-50) 50 ca. 50 Replacement odontostyle 76 Anterior end to guide rng 25 24 (23-25) 22 23.35 Postcorpus 88 91 (88-93) Anterior ovary 338 288 (190-360) 440 Posterior ovary 280 242 (210-260) 440 Tail 44 46 (42-50) 52 Hyaline area of tail 12 12.5 (12-13) 8 Width Lip 11 11.3 (ll-12) 10 10~: Postcorpus 19 19.1 (18-20) Midbody 50 47.5 (46~49) 36 Anus 30 30.5 (28-32) 25 Ratios and percentages a 77 86 (84-89) 83 88 b 10.5 11.7 (10.5-13.5) 10.7 12.3 c 87 89 (84-98) 57 88 c' 1.5 1.5 (1.4-1.6) 2.08 1.54~ V 46.4 45.8 (44.8--46.8) 48 ? Mean, range in parentheses. $ Calculated fi'om Thorne's drawing. base. Odontostyle slender, diameter about Diagnosis 2 ~m at base, odontophore base slightly Longidorus sylphus differs from other spe- muscular and swollen. Postcorpus length cies of the genus in the following combina- about 4.5 times its width, tapering anteri- tion of characters: female lip area body orly. Esophago-intestinal valve about half walls parallel in the approximate range of the width of the muscular esophagus base, the amphids, body at level of amphids 11- conically rounded posteriorly, slightly 12 ~tm wide, conical tail about 1.5 times the longer than wide. Vulva not elevated. Va- anal body width with a finely rounded tip, gina perpendicular to body axis with thick- odontostyle 70-80 ~m long, odontophore ened cuticle lining, encircled by a muscular base slightly muscular and swollen, and band at junction with uterus. Sphincter body length 3.5-4.5 mm. joining uterus and oviduct not prominent, sperm not observed in genital tract. Ova- Relationships ries paired, opposed, reflexed. Prerectum 8-11 anal body widths in length. Rectum Longidorus sylphus most closely resembles about one anal body width in length. Tail L. africanus Merney, L. conicaudoidesJacobs conical-rounded, with dorsal curvature, & Heyns, and L. auratus Jacobs & Heyns in rounded tip diameter 4-6 p~m. Hyaline body, tail, and odontostyle length, lip area of tail about as long as wide. width, lip and tail shape, distance from an- Male: Unknown. terior end to the guide ring, and c'. Longi- Juvenile (pre-adult stage): Resembles fe- dorus sylphus differs from these three spe- male except for undeveloped genital struc- cies by having a slight swelling at the base tures and longer tail. of the odontophore and a shorter distance Amended Descriptions of Longidorus: Robbins, Brown 97 to the guide ring (23-25 ~m vs. 26-33, 27- Nematode Collection in Beltsville, Mary- 33, 27--33 ~xm, respectively). From L. af- land. ricanus and L. conicaudoides it differs by Note: The L. sylphus juvenile specimen, having a slightly shorter odontostyle (72- and that of L. crassus, were each identified 80 p.m vs. 82-93, 82-93 txm, respectively). as preadults which, according to the no- The tail of L. sylphus is slightly longer than menclature proposed by Robbins et al. that of L. auratus (42-50 Ixm vs. 33-41 (12), are referred to as J4. The preadult in Ixm), also the tail terminus is less rounded species for which there is unequivocal evi- than for L. auratus or L. africanus. dence of only three juvenile stages are re- ferred to as JIII.