A new Thelastomatidae , Oryctophila bonaerensis sp . nov . ( Nematoda ) parasite of curculionid beetle larvae of Prosalbus rufus ( Coleoptera : Curculionidae ) from Argentina

Oryctophila bonaerensis sp. nov. parasitizing curculionid beetle larvae from Argentina, is described and illustrated. The species is characterized by a prominent genital cone and a short and filiform tail appendage. Female with vulva at midlenght of body, vagina long, S-shaped, monodelphic, opistodelphic. Male with one club-shaped spicule. Genital papillae arranged as follows: one pair of large preanal papillae and three pairs of postanal papillae of various sizes: a pair of medium sized papillae is immediately posterior to the anus, followed by a pair of large papillae, and one pair of small papillae at the base of the caudal appendage.


Larvae of Prosalbus rufus
from Gorina (34°58'S, 57°54'W), La Plata, Buenos Aires Province, Argentina, were collected by hand and placed in individual vials.We followed POINAR's (1975) dissection protocol, keeping insects at 5°C for 10 minutes, and then dissecting them in Petri dishes filled with distilled water under a Zeiss stereoscope.The nematodes were euthanized in 60°C distilled water for two minutes.They were subsequently removed to 50% TAF solution in water for 48 hours, and then transferred into pure TAF.The nematodes were transferred from the fixative to glycerol for clearing.Fixed specimens were used for drawings using a camera lucida mounted on a Zeiss compound microscope.All measurements are in µm (holotype male and allotype female), with ranges in parenthesis (paratypes).

Figs 1-6
Description: small nematodes; cuticle annulated throughout length of body.Female: cephalic extremity (Fig. 1) formed by circumoral annule (diameter 40 µm) and enlarged second annule (diameter 52 µm).Buccal cavity short, cylindrical with simple walls.Esophagus with a corpus, an isthmus and a basal bulb.Nerve ring located in the middle of the corpus.Excretory pore situated at mid-isthmus level.Female with vulva at midbody, with posterior lip well developed (Fig. 3 long and filiform (Fig. 5).Male: cephalic extremity (Fig. 2) formed by simple annule (diameter 17 µm).Stoma simple with thin walls.Nerve ring at midlevel of corpus.Excretory pore at mid-isthmus level.Genital cone prominent, with a short and filiform tail appendage (Fig. 6).The male with testis extending to middle of the body.One club-shaped spicule, without gubernaculum.The genital papillae arranged with one large pair preanal papillae and three pairs postanal, of these, one pair medium size just behind the anus, medial pair large and distal pair small at base of the caudal appendage (Fig. 4).
Site in host: intestine, midgut.Etymology: the name refers to the geographical region where it is found.
Type material: holotype male and allotype female are deposited in the Helminthological collection of Museo de Ciencias Naturales de La Plata, nº 5483, paratypes in the Nematological collection of CEPAVE (Dr.Camino's laboratory).

DISCUSSION
Females of Oryctophila bonaerensis sp.nov.are similar to four other species of Oryctophila: O. alatum (Johnaston, 1914) Basir, 1956, parasite of a cetonid beetle larva from Australia; O. crimense (Skrjabin, 1927) Basir, 1956, from myriapods from Russia;O. myriapodicola (Skrjabin, 1916) Basir, 1956, from myriapods from Africa, and O. sphaeropoli (Parona, 1896) Basir, 1956, from millipedes from Indonesia.The female reproductive apparatus of these species is similar, including a monodelphic, opistodelphic condition.Two traits distinguish O. alatum from O. bonaerensis: First, the latter has a pair of caudal papillae near the anus; second, the intestine of O. bonaerensis is dilated anteriorly to form a cardia.The males have not been described for the other three species; therefore, the comparisons below are based on females.O. crimense has larger eggs (113 x 85 µm vs in O. bonaerensis (64-70.8x 41-46.2µm) and a more anterior excretory pore (in the middle of the corpus).Oryctophila myriapodicola differs by having a shorter tail (about one-fifth of the body, 460-510 µm), and the intestine enlarged anteriorly forming a distinct cardia, which occupies almost the entire width of body.Finally, J. sphaeropoli is characterized by having a distinct sub-spherical swelling of the posterior end of the corpus in the shape of a pseudobulb and a spicate, filiform tail of about one-third the length of the body (980-1430 µm).
Investigador CIC, Centro de Estudios Parasitológicos y de Vectores,CEPAVE.Calle 2, nº 584, 1900 La Plata, Argentina.E-mail: nemainst@cepave.edu.arABSTRACT.Oryctophila bonaerensis sp.nov.parasitizing curculionid beetle larvae from Argentina, is described and illustrated.The species is characterized by a prominent genital cone and a short and filiform tail appendage.Female with vulva at midlenght of body, vagina long, S-shaped, monodelphic, opistodelphic.Male with one club-shaped spicule.Genital papillae arranged as follows: one pair of large preanal papillae and three pairs of postanal papillae of various sizes: a pair of medium sized papillae is immediately posterior to the anus, followed by a pair of large papillae, and one pair of small papillae at the base of the caudal appendage.KEY WORDS.Nematodes; Entomoparasitic; Insect; taxonomy.