#Paraxiphidorus miichelluci$ n.g., n.sp. est décrit sur trois spécimens provenant de sol non cultivé d'Argentine. Ce nouveau genre est caractérisé par : région labiale en relief; amphides en étrier à ouverture large; odontostyle à base fourchue; odontophore à ailettes faiblement développées; guide du stylet en position postérieure; suppléments ventromédians dépassant le niveau des spicules; queue convexe-conoïde. Il ressemble à #Xiphidorus$ Monteiro, 1976 et #Paralongidorus$ Siddiqi, Hooper & Khan, 1963 mais diffère du premier par la structure de l'amphide et du second par celle du stylet, la position du guide du stylet, ainsi que par le nombre et la disposition des suppléments ventro-médians (Résumé d'auteur

Chaves, E.

Coomans, A.

Name not available

Paraxiphidorus michelluci n.g., n.sp. from Argentina (Nematoda : Longidoridae)

Horizon / Pleins textes

Fundam. appl. Nematol., 1995, 18 (3), 303-306
Paraxiphidorus michelluci n.g., n.sp.
from Argentina (Nematoda : Longidoridae)
August COOMANS* and Eliseo CHAVES**
* Instituut voor Dierkunde, Universiteit Gent, K. L. Ledeganckstraat 35, 9000 Gent, Belgium and
** INTA-Estacion Experimental de Balcarce, 7620 Balcarce, Argentina.
Accepted for publication 28 September 1994.
Summary - Paraxiphidorus mu:helluci n.g. n.sp. is described based on three specimens from uncultivated soil in Argentina. The new
genus is characterized by an expanded, offset lip region; stirrup-shaped amphids with wide aperture; odonrostyle with forked base,
odontophore weakly flanged; guiding ring far posterior; ventromedian supplements outside range of spicules and convex-conoid
tail. Ir resembles Xiphidorus Monteiro, 1976 and Paralongidorus Siddiqi, Hooper & Khan, 1963 but differs from the former in
amphid structure and from the latter in stylet structure, position of guiding ring and in number and position of the supplements in
the male.
Résumé - Paraxiphodorus michelluci n.g., n.sp. provenant d'Argentine (Nernatoda: Longidoridae) - Paraxiphidorus
michelluci n.g., n.sp. est décrit sur trois spécimens provenant de sol non cultivé d'Argentine. Ce nouveau genre est caractérisé par:
région labiale en relief; amphides en étrier à ouverture large; odontostyle à base fourchue; odontophore à ailettes faiblement
développées; guide du stylet en position postérieure; suppléments ventromédians dépassant le niveau des spicules; queue convexe-
conoïde. TI ressemble à Xiphidorus Monteiro, 1976 et Paralongidorus Siddiqi, Hooper & Khan, 1963 mais diffère du premier par la
structure de l'amphide et du second par celle du stylet, la position du guide du stylet, ainsi que par le nombre et la disposition des
suppléments ventro-médians.
Key-words : Longidoridae, nematodes, Paraxiphidorus.
During a survey of the nematofauna from several re-
gions in Argentina in 1984, three specimens were found
of a hitherto unknown longidorid which upon doser
examination appeared to represent a new genus. Despite
repeated attempts to collect more specimens none were
found. In view of the fact that this genus seems to occu-
py an interesting position in the family, we decided to
describe it based on the rwo males and one last stage
Juvenile.
The specimens were fixed with hot 4 % formalde-
hyde, extracted by centrifugation-flotation and mounted
in pure dehydrated glycerine using a modified Sein-
horst's (1959) method.
Paraxiphidorus n.g.
DlAGNOSIS
Lip region expanded and weil offset. Amphids with
wide stirrup-shaped fovea and wide aperture. Base of
odontostyle forked. Odontophore with weakly devel-
oped basal flanges. Cheilostome long; guiding ring
around the posterior third of the odontostyle in resting
position. No dilaiores buccae (= cheilostome retractors).
No compensation sacs. Stylet retractors and pharyngeal
retractors present. Pharyngeal gland pattern with small
DN far behind corresponding ourlet (DO-DN = 14 %
of bulb length); SN larger than DN. Males with post-
erior ventromedian supplements outside the range of the
spicules. Tai! convex-conoid with broadly rounded ter-
mmus.
fSSN 1164-5571/95/03 S 4.00/ © Gauthier-Villars - ORSTOM
TYPE AND ONLY SPECIES
P. michelluci n.g., n.sp.
RELATIONSHIPS
The new genus resembles Paralongidorus Siddiqi,
Hooper & Khan, 1963, especially those Paralongidorus
species with expanded lip region and wide amphidial
fovea. However, the new genus differs in the following
aspects: z) dearly forked base of the odontostyle;
iz) weakly flanged odontophore; iiz) far posteriorly situ-
ated guiding ring; iv) smaller number of ventromedian
supplements with the posteriormost one weil in front of
the spicules.
The new genus resembles Xiphidorus Monteiro, 1976
in the structure of the stylet and guiding apparatus, in
the position of the guiding ring and in number and
position of the male supplements, but it differs in the
shape and aperture of the amphidial fovea.
Paraxiphidorus rnichelluci n.g., n.sp.
MEASUREMENTS
see Table 1
DESCRIPTION
Male: Body long and slender, more or less spiral upon
fixation. Lip region hemispherical, offset by a marked
constriction. Body cutide behind constriction bulging
303
A. Coomans & E. Chaves
Table 1. Measurements of type specimens of Paraxiphidorus
michelluci n.g., n.sp. (ail absolute measurements in J.un, except L
in mm).
Male Juvenile
Holorype Paratype
L 5.91 4.75 4.52
a 118 116 113
b 14.9 14.9 14.7
c 164 140 139
c' 1.03 1.14 1.05
T 54 48
Lip region width 14 12 12
Lip region height 5 5 5
Amphid aperture 12 10
Odontosty1e 123 128.5 108.5
Odontophore 52 43 43
Replacement odon-
tostyle 1305
Guilding ring 115 113 97
Pharynx:
- sIender part 152 140 193
- bulb Oength x width) 87x 19 71 x 15
Hemizonid 190 191
Nerve ring 204 201 198
Neck 1ength 396 317 307
Body diameter :
- at cardia 43 37.5 34.5
-at midbody 50 41 40
- at anus (cloacaJ
opening) 37 38.5 34
Prerectum 384 366 370
Tail 36 34 32.5
Spicule 1eft 57 55
Spicule right 56 54
Lateral guiding piece
left 13 14
Lateral guiding piece
right 12 14
Supplements from
cloacal opening :
- paired papilla 18 19
- pap. 1 92 78.5
- pap. 2 96 92
- pap. 3 107 107
-pap.4 124 127
- pap. 5 138 148
- pap. 6 154 172
- pap. 7 173
outward due to local thickening of median layer. Ante-
rior sensilla with typical 6 + 10 arrangement. Amphids
with stirrup-shaped fovea and wide slit-like aperture oc-
cupying 9/1 Oth of the width at the constriction. Lateral
304
body pores numerous, but dorsal and ventral body pores
few. Neck region with 9-10 (paratype) to 13-17 (holo-
type) lateral, 1 (holotype) or 2 (paratype) dorsal and 4
(holotype) or 5 (para type) ventral body pores. Odontos-
tyle long and slender, with forked base. Guiding appara-
tus as in Xiphidoms, i.e. with single guiding ring located
far backward and without compensation sacs. Odon-
tophore also comparable to Xiphidorus) but flanges
somewhat less developed. Stylet retractors present but
weakly developed, their nature (double or single) cannot
be determined on the available material. Pharyngeal re-
tractors as in Xiphinema and Xiphidoms. Slender part of
pharynx not offset from eruarged part. Latter at first
conical, then cylindrical. Dorsal gland nucleus smaller
than ventrosublateral ones. Positions of outlets and nu-
clei as percentage of bulb length (holotype) : DO: Il,
DN: 25, RSN : 48.5, LSN: 52, SO : 85. Pharyngo-
intestinal junction wide and flattened, with conoid cen-
tral valve. Intestine with thin wall, three or four cells in
circumference. Prerectum about twice as long as the
region of copulatory muscles. Tail dorsaUy convex-co-
noid with broadly rounded terminus, with 2-3 caudal
pores. Reproductive system confined to posterior body
half, short in para type, but longer in holotype due to
large number of spermatozoa. Both testes 520 J.l.m long
or Il % of the body length in the para type and 1040 J.l.m
long or 17.6 % of the body length in the holotype. Sper-
matozoa 5.8 J.l.m (n = 10) long. Vas deferens in the holo-
type packed with small, highly refractive granules till
opposite the anteriormost copulatory muscles, then
finely granular till it merges with the very short rectum to
form the cloaca. In the para type the vas deferens is filled
with the refractive granules throughout its length. There
are 32 (holotype) to 37 copulatory muscles and four or
five pairs of ejaculatory glands in the posterior body
region. Behind the last copulatary muscle three smaller
muscles running inward at each side from the latero-
dorsal body wall along the rniddle part of the spicule and
bending tO\vards the ventral side of the spicule. In the
tail there are 4-5 caudal copulatory muscles. In addition
to the paired genital papilla opposite the level of the
middle of the spicules, there are seven (holotype) or
six ventromedian supplements. The anteriormost of
these is less developed and anterior to the first
copulatory muscles; the posteriormost ventromedian
supplement occurs at about two spicule lengths in front
of the cloacal opening. There are five subventral
body pores in the region of the copulatary muscles.
Spicules stout, L-shaped with posterior dorsal
thickening.
Juvenile: Agreeing in most aspects with the males,
except for genital structures. Tail conoid-rounded with
three caudal pores. Judging from its size, length of re-
placement odontostyle and development of genital pri-
mordium (61 x 9 J.l.m) and lack of a spicular prirnordi-
um it seems ta be a young preadult female (or J 4) stage.
Fundam. appl. Nematol.
Paraxiphidorus michelluci n.g., n.sp.
R
~c?
~c::::"\J ~=
~=
S
30 ~m
B-F,H,I,N-S
10 ~m
G
sa ~m
A,M
Fig. 1. Paraxiphidorus michelluci n.g., n.sp. A : Neck region; B : Amen'or end, median view; C : Amen'or end, surface view; D : Amen'or
end, dorsa-ventral view; E. Posterior parI of slylel; F: Same, bUI of juvenile; G: Base of odonlOslyle [J : Paralongidorus cebensis (Jar
campan'son); 2: Funelional odomoslyle ofjuvenile; 3 : Replacemem odonlOslyle ofjuvenile}; H: Pha1)>ngeal bulb; 1: Tail ofjuvenile; J :
Hololype male; K: Paralype male; L: Juvenile paralype; M : Poslen'or body region ofmale; N: Tail end ofmale; 0 : RighI spicule; P, Q:
LaIerai guiding pieces; R.' Sperm; S : Spicules and laleral guiding pieces of paralype male. (A-C, E, H, J, M-R are from hololype).
Vol. 18, n° 3 - 1995 305
A. Coomans & E. Chaves
The base of the odontostyJe is less clearly forked, but the
base of the replacement odontostyle is forked as in the
male.
TYPE LOCALITY AND HABITAT
Uncultivated soil, Campo Arana, Pdo. de Tandil,
Buenos Aires Province, Argentina. Collected by E.
Chaves, 20 Aug. 1984.
TYPE SPECIMENS
Holotype male and paratype juvenile on slides
n° 3809 and 3810 respectively in the Nematode Collec-
tion of the Zoology Institute, University of Ghent, Belgi-
um. Paratype male in the Nematode Collection
306
of INTA-Estaci6n Experimental de Balcarce, Argenti-
na.
References
MONTEIRO, A. R. (1976). XlphidoTUS yepesara n.gen., n.sp.
(Nematoda : Longidoridae), [rom Brazil. Nemal.Ol. Medit., 4 :
1-6.
SEINHORST, ]. W. (1959). A rapid method for the transfer of
nematodes [rom fIxative to anhydrous glycerin. Nemalologica,
4: 67-69.
SlDDIQI, M. R., HOOPER, D. ]. & KHAN, E. (1963). A new
nematode genus ParalongidoTUs (Nematoda : Dorylaimoidea)
with descriptions of two new species and observations on
ParalongidoTUs cùri (Siddiqi, 1959) n.comb. Nemal.Ologica, 9 :
7-14.
Fundam. appl. NemalOl.


Paraxiphidorus michelluci n.g., n.sp. from Argentina (Nematoda : Longidoridae)

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