Camino, N.B.

Stock, S.P.

Horizon / Pleins textes

Fundam. appl. NemalOl., 1992, 15 (l), 15-18.
Hexamennis ovistriata n. Sp. (Nematoda : Mermithidae)
a parasite of the grasshopper Staurorhectus longicomis
Giglio-Tos (Orthoptera : Acridiidae) in Argentina
S. Patricia STOCK and Nora B. CAMINO
Centro de Estudios Parasitol6gicos y de Vectores (CEPA VE), Calle 2, No 584, 1900 La Plata, Argentina.
Accepted for publication 4 December 1990.
Summary - Hexamennis ovistriala n. sp. (Nematoda : Mermithidae) a parasite of the grasshopper SlaurOrheclUs longicornis
Giglio-Tos (Orthoptera : Acridiidae) is described and il1ustrated. Ir is charaeterized by the presence of large, flask-shaped amphids,
vagina J-shaped, IWO medium sized spicules and six rows of genital papillae : fourteen pre-anal and eighteen post-anal papillae. Eggs
with three longitudinal lines.
Résumé - Hexamermis ovistriata n. sp. (Ne7natoda : Mennithidae) parasite de la sauterelle Staurorhectus longicor-
nis Giglio-Tos (Orlhoptera : Acridiidae) en Argentine - Hexamennis ovistriala n. sp. (NemalOda : MennithidaeJ, parasite de
la sauterel1e SlaurorheClus longicornis Giglio-Tos (Orthoptera : Acridiidae) est décrit et illustré. Il est caractérisé par la présence de
grandes amphides en forme de bouteille, un vagin en forme de J, la présence de deux spicules de taille moyenne et de six rangées
de papilles génitales: quatorze préanales et dix-huit postanales. Les œufs sont ornés de trois lignes longitudinales.
Key-words : Hexamermis, grasshopper.
During the summer of 1989, we discovered a mermÎ-
thid parasitizing nymphs of the grasshopper Scaurorhec-
tus longicornis Giglio-Tos, 1876, at Brandsen, Buenos
Aires, Argentina. Twenty different genera of acridids
parasitized by Hexamennis species have been reported
from USA, Europe and South America.
Further investigations showed that this mermithid is
new to science. It is described and figured below, as
Hexamennis ovistriata n. sp.
Material and methods
Nymphs of Staurorheetus longicornis, were collected
with a sweepnet from the field at Brandsen. They were
placed in cages which had plastic containers with moist
soi!. The nematodes that emerged were collected from
the moist soil and kept in moist soil until they matured.
Adults and post-parasitic juvenile nematodes were
observed alive and then killed in distilled water at 60 oC
for 3 s, flXed in TAF and processed to glycerol by
Seinhorst's method for taxonomic studies (Curran &
Hominick, 1980). Histological sections to determine the
arrangment of the longitudinal chords were made by
fixing the nematodes in Bouin's fluid, passing through
alcohol series to parapiast, seetioning at 10 Ilm and
staining with hematoxilin-eosin. An apical view of the
head was prepared in glycerine jelly (Hooper, 1970).
Drawing and measurements were made from live and
fixed specimens with a camera lucida microscope and
micrometer.
Hexamermis ovistriata n. sp.
(Fig. 1)
MEASUREMENTS
Female (paratypes; n = 23). L = 40-355 (126 ±
116.36) mm; head diam. at cephalic papillae level
52-95 Ilm; (71 ± 11.61) Ilm; maximum body diam.
144-560 Ilffi (282.8 ± 137.27) Ilm; diam. at posterior
end of trophosome leveI = 100-381 (208. 19 ±
86.97) Ilm; dist. ant. end to nerve ring = 220-470
(349.19 ± 67.25) Ilm; V = 43.48-65.1 (52.12 ± 7.31);
length ant. portion of vagina = 44-100 (63 ±
23.42) Ilm; vagina length = 80-500 (260 ± 141.91) Ilm;
vagina width = 52 + 125 (98 ± 37.20) Ilm.
Male (paratypes; n = 15). L = 13-68.15 (34 ±
18.52) mm; head diam. at cephalic papillae level =
49.5-64 (57.2 ± 4.87) Ilm; body diam. at nerve ring
leveI = 90-140 (115.5 ± 14.98) Ilm; body diam. =
139-200 (168.5 ± 23.93) Ilm; dist. ant. end to nerve
ring = 246.5 (276 ± 19.83) Ilffi; taillength = 142-309.5
(200 ± 59.84) Ilffi; spicules length = 127.5-240
(167.5 ± 30.52) Ilm; width of spicules in the middle =
9-24 (14.5 ± 4.03) Ilm.
HOLOTYPE (male). L = 48 mm; head diam. at cepha-
lic papillae leveI = 58 Ilm; body diam. at nerve ring
level = 100 Ilm; maximum body diam. = 9 Ilm; body
diam. at anus level = 151 Ilm; dist. ant. end to nerve
ring = 278 Ilm; tail length = 203 Ilffi; spicules
length 162.5 Ilm; width of spicules in the middle =
ISSN 1164-5571/92/0//1504 $ 2.40/© Gauthier-Villars - ORSTOM 15
S. P. Scock & N. B. Gamina
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Fig. 1. Hexamennis oviscriaca n. sp. A : Dorsal view of male head; B : Dorsal view of female head; C : Cross section at midbody,
D : Lateral view of post-parasiric juvenile tail; E : Vagina; F : En face view of male head; G : Lateral view of male tail; H : Ventral
view of male tail. (Bars: A-E = 100 J.lm; F-f = 50 J.lm.J
16 Fundam. app/. Nemaco/.
11.5 ~m; length and width of amphids = 40.5 x
14.5 ~m.
ALLOTYPE (female). L = 135 mm; head diam. at
cephalic papillae level = 72.5 ~; body diam. at nerve
ring level = 166.5 ~m; maximum body diam. =
260 ~m; body diam. at posterior end of trophosome
level = 210 ~m; dist. ant. end to nerve ring = 357.5 ~m;
V = 54; length ant. portion of vagina = 54 ~m; vagina
length = 325.5~; vagina width = 110 ~m; length and
width of amphids = 23.5 x 6 ~m.
DESCRlPTION
Adults .. Long white nematodes. Cuticle with criss-
cross fibres, visible with light microscope. Head homo-
cephalic. Six cephalic papillae surrounding the mouth.
Amphids large sized, flask-shaped. Amphidial opening
smal!. Six hypodermal chords : lateral chords containing
three rows of cells ail along the body; the dorsal,
subventral and ventral chords containing one row of
cells. Mouth terminal and centra!.
Females .. Vulva a longitudinal slit. Cuticle thin at the
vulval canal. Vagina J-shaped, perpendicu1ar to the longi-
tudinal body axis. Anterior portion of the vagina weil
muscularized, with a descending branch and another
ascending whose terminal portion makes a loop before
joining the uterus. Anterior uterus ventrally situated,
connecting vagina direcùy anterior to vulval region.
Head rounded, with a slight neck constriction. With or
without tail appendage (juvenile females with tail ap-
pendage were found in a 6 % of the population).
Males .. Spicules paired, medium sized, exceeding the
width of body at anal level, never twisted. Spicule tip
rounded, simple, lacking ornamentation. Six rows of
genital papillae, double row of lateral papillae : the
external row with thirteen papillae and the internai one
with twelve papillae irregularly arranged; ventral row
with fourteen pre-anal papillae : a single papilla at the
beginning of the spicules, three pairs of papillae, a single
papilla, and three pairs of papillae; eighteen post-anal
papillae : two triplets of papillae, five pairs of papillae
ending with two single ones. Head structure similar to
that of the female. Amphid size greater in males than in
females. With or without tail appendage (juvenile males
with tail appendage were found in a 4 % of the popu-
lation.)
Eggs .. Not embryonated in uterus. Chorion composed
of two layers, outer layer with three longitudinal lines
and thin inner, smooth and clear; no byssi. Eggs =
120-165 (148 ± 23.1) x 73-105 (92 ± 16.27) ~m.
Post-parasiticjuveniles .. Dimensions similar to that of
adults. With or without caudal appendage.
TYPE HOST AND LOCALITY
Nymphs of Slaurarheetus longicornis Giglio-Tos,
1976 (Orthoptera : Acridiidae). Brandsen, Buenos Aires,
Argentina.
Vol. 15, nO 1 - 1992
Hexamermis ovistriata n. sp.
TYPE SPECIMENS
Holotype .. deposited in the helminthological collection
in the CEPAVE. Allotype and paralypes : deposited in
the Invertebrata Division, Faculty of Natural Sciences
and Museum, La Plata, Buenos Aires, Argentina.
DIAGNOSIS
Mermithidae Braun, 1883; Hexamermis Steiner,
1924. Hexamermis ovistriata n. sp. is characterized by :
i) the presence of large, flask-shaped amphids which in
profile do not pass inside the head almost to the oeso-
phageal canal; ii) a J-shaped vagina, situated transver-
sally near the middle of the body; iii) spicules medium
sized and slightly curved; iv)six rows of genital papillae
(fourteen pre-anal; eighteen post-anal); v) eggs with
three longitudinal lines of striations.
RELATIONSHIPS
The new species is placed in the genus Hexamermis
because, although its amphids are large, they are actually
much smaller than those of Amphidamermis Filipjev,
1934.
Also, the preparasitic stage of H. ovistriala n. sp. lacks
the post nodaJ region of the body, an oustanding charac-
ter of the members of the genus Agamermis Cobb,
Steiner & Christie, 1923 and the parasitic and post-
parasitic stages of H. ovistriata n. sp. lack the nodal scar
that is present in Agamermis species.
Hexamermis ovistriata n. sp. shares the morphology of
its vagina U-shaped) with nine species of the genus
Hexamermis Steiner, 1924 : H. albicans (Siebold, 1848)
Poloshentsev & Artyuskhovsky, 1959 from Europe, Asia
and America; H. arvalis Poinar & Gyrisco, 1962 from
USA; H. brevis (Hagmeier, 1912) Polozhentsev &
Artyukhovsky, 1959 from Europe; H. cathetospiculae
Poinar & Chang, 1985 from Malaysia; H. cavicola
Welch, 1963 from Australia; H. elangata Kaiser, 1977
from Europe; H. micraamphidis Steiner, 1925 from Java
Islands; H. hortensis Camino & Stock, 1989 from
Argentina.
H. albicans differs from the new species in the arran-
gement of the genital papillae in the males: four to eight
pre-anal and five to nine post-anal papillae.
H. arvalis can be separated by having a vagina situ-
ated parallel to the longitudinal body axis and in the
arrangement of the genital papillae : three to six irregular
and discontinuous rows.
H. brevis has very short spicules (50-130 ~m) and the
post-anal papillae are placed in several rows to triplets.
H. cathetospiculae differs from H. avistriata n. sp. in
the size of the spicules (289-334 ~m) and the genital
papillae having three broken (double) rows; lateral
double rows containing 20-32 papillae each, extending
anteriorly past the cloacaJ opening, but ooly half the
length the spicules; median double row of20-25 papillae
extending anteriorly almost the lateral papillae.
17
s. P. SlOck & N. B. Gamino
H. cavicola differs in the presence of several irregular
rows of genital papillae (eight anal and ten post-anal).
H. elongata differs from H. ovislriata n. sp. by having
large spicules (130-230 llm) and amphids situated lat-
erally.
H. incisura differs in the size of the spicules, which are
very short (110 llffi) and thin at their beginning.
H. lineata can be separated from the new species by
having spicules that are thin at their beginning
(185-250 llm) and by the small amphids situated behind
the cephalic papillae.
H. microamphidis differs from H. ovislriata n. sp. by
having shorter spicules, with a length smaller than body
diameter at anus level, and the very small amphids.
H. horlensis differs in the amphids, smaller than those
of H. ovislriata n. sp., and in the distribution of the
genital papillae.
References
CAMINO, N. B. & STOCK, S. P. (1989). Hexamermis horlensis n.
sp. (Nematoda : Mermithidae), parasita de larvas de Spodop-
lera frngiperda (Smith) (Lepidoptera : Noeruidae) en Argen-
tina. Revca iber. Parasic., 49 : 329-333.
CURRAN,]. & HOMINICK, W. M. (1980). Effeet of mounting
methods on taxonomie eharaeters of adult male mermithids
(Nematoda : Mermithidae). NemalO/ogica, 26 : 455-466.
HOOPER, D. ]. (1970). Handling, foong, staining and mounting
nematodes. In : Southey, ]. F. (Ed.). LaboralOry mechods for
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work wich plane and soi/ nemalOdes. London, M.A.F.F.,
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KAISER, H. (1977). Untersuchungen zur Morphologie, Bio-
metrie, Biologie und Systematik von Mermithiden. Ein
Beitrag zum Problem der Trennung morpholgiseh schwer
unterscheidbarer Arten. Zoo/. Jb., Abc. Syscemacik, 104 :
20-71.
POINAR, G. O. Jr. & CHANG, P. (1985). Hexamermis cachelOspi-
cu/ae n. sp. (Mermithidae : Nematoda) a parasite of the riee
stemborer, Tryporyza incerculas (W1k.) (Pyralidae : Lepido-
tera) in Malaysia. J. NemalO/., 17 : 360-363.
POINAR, G. O. Jr. & GYRISCO, G. G. (1962). A new mermithid
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Insece Pach., 4 : 201-206.
POLOZHENTSEV, P. A. & ARTYUKHOVSKY, A. K. (1959). [On the
systematies of the family Mermithidae Braun, 1883 (Dory-
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STEINER, G. (1924). Beitrage zur Kenntnis der Memithiden. 2.
Teil. Mermithiden aus Paraguay in der Sammlung des
Zoologischen Museums zu Berlin. Zencbl. Baki. ParasicKde,
62 :90-110.
STEINER, G. (1925) : Mermithids parasite in tea bug (He/ope/lis
anlOnii Sign.). Meded. Proefsc. voor Thee, 44 : 10-16.
WELCH, H. E. (1963). Amphimermis bogongae sp. nov. and
Hexamermis cavico/a sp. nov. from the Australian bogong
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Amphimermis Kaburaki & Imamura, 1932 (Nematoda :
Mermithidae). Parasit%gy, 53 : 55-62.
Fundam. appl. NemalO/.


Hexamermis ovistriata n. sp. (Nematoda : Mermithidae) a parasite of a grasshopper Staurorhectus longicornis Giglio-Tos (Orthoptera : Acridiidae) in Argentina

Hexamermis ovistriata n. sp. (Nematoda : Mermithidae) a parasite of a grasshopper Staurorhectus longicornis Giglio-Tos (Orthoptera : Acridiidae) in Argentina

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