A new thelastomatid of the genus Blatticola Schwenk , 1926 ( Nematoda , Th elastomatidae ) a parasite of cricket ( Orthoptera , Gryllidae ) from Argentina

Blatticola biannulata n. sp. (Oxyurida, Thelastomatidae) a parasite of the cricket Anurogryllus muticus (De Geer) (Orthoptera, Gryllidae) from Argentina, is described and illustrated. This is the second species of the genus Blatticola found parasitizing cricket. Females of this new species is characterized by the cuticle that is annulated from the anterior end up to the middle of the body, the mouth opening being subtriangular in shape surrounded by 8 cephalic papillae, the short stoma with two semicircles sclerotised and the telostoma with one movable tooth, small pore shaped amphids, an oesophagus divided into three parts, anterior cylindrical corpus, isthmus distinct, and basal bulb valvated, the nerve ring situated arounded the isthmus, the intestine broadest anteriorly, eggs oval, smooth shell, in apical view show a triangular section, with three wings, the dorsal one and two lateroventrals, males with one pair of preanal, and two pairs of postanal papillae, and the tail appendage short, conical and pointed, the female has in the top an structure of anchorage, like structure of grasp. [P]

solution with tap water (1:3), the insects were put in plastic containers by hand and later transferred to individual vials.The insects were kept at 5°C for 10 min, and then dissected in Petri dishes fi lled with distilled water under a stereoscope microscope.A transverse incision was made along the posterior end of the abdomen and the digestive tract was removed to obtain the parasites.The nematodes were killed by placing them in distilled water at 60°C for 2 min.They were removed to 50% TAF solution in water for 48 h, then into pure TAF.Fixed specimens were used for drawings and measurements with the aid of a lucida camera mounted on a Zeiss compound microscope.All measurements are in μm, and presented as the mean and standard deviation, with ranges in parenthesis.Scanning electron micrographs obtained using a JEOL JSM-100 scanning electron microscope, and were used to describe the external ultrastructure of the cuticle of the nematodes.Specimens prepared for scanning electron microscopy were fi xed in a cold solution of 1.5% glutaraldehyde/ 1.5% formaldehyde in 0.1M acidulate buffer (pH 7.35) overnight, postfi xes in cold aqueous solution of 1% osmium peroxide overnight, transferred to 70% ethanol and hydrated in ethanol.The nematodes were dehydrated in a graded series of ethanol washes from 10% to 90%, to fi nish the dehydration in absolute alcohol (100 %), and then critical point dried with liquid CO 2 , mounted on SEM stubs, and coated with gold for 1 hour.

Introduction
The genus Blatticola was proposed by Schwenk (1) in 1926, to designating B. blatticola as type species.In 1932 Chitwood (2) considered this species a synonym of B. blattae Graeffe (3).The confused taxonomicy history of the genus and of the type species was clarifi ed by Dale (4) in 1966.The emended diagnosis of the genus given earlier was modifi ed by Adamson & van Waerebeke (5) to accommodate the species described by Chitwood (2) in a revision of the group of thelastomatids.The genus Blattellicola Basir (6) and Blatellicoloides Farooqui (7) agree with Blatticola in all essential respects and they are considered synonymous.All the species described up to the present are parasites of cockroaches from all major regions of the world.While conducting fi eld surveys on agricultural pests in Argentina in areas of La Plata, Buenos Aires province, we found nymphs of crickets parasitized by a species of this group of thelastomatids.Achinelly and Camino (8) described a new species Blatticola cristovata, which was the fi rst report from a cricket in Argentina.In this contribution we report another new species of the genus, Blatticola biannulata n. sp. a parasite of the cricket Anurogryllus muticus (De Geer) (Orthoptera, Gryllidae) found in Argentina.
A new thelastomatid of the genus Blatticola Schwenk, 1926 (Nematoda, Thelastomatidae) a parasite of cricket (Orthoptera, Gryllidae) from Argentina 35  Males smaller in size than females.Cuticle slightly annulated along body.Amphids small and pore-shaped.Cephalic papillae not visible with light microscopy.Stoma longer than broad, with two semicircles sclerotised; telostoma with one tooth, like in female.Oesophagus and intestine similar as in female (Figures 1C and 1E).Nerve ring surrounding isthmus.Excretory pore posterior to anterior end of intestine.Testis single, extending anteriorly, and then refl exed posteriad linearly towards posterior end of the body.Ejaculatory duct evident.Spicule single, small, linear, straight forming an arrow, without sculpture, tip pointed (Figure 1F).Capitulum and gubernaculum absent.Genital papillae arranged ventrolaterally in one pair of preanal papillae, and two pairs of postanal papillae (Figure 2J).Tail appendage short, wide, conical and pointed (Figure 1F).
Male Small nematodes.Cuticle of the female annulated from anterior end up to middle of body.The fi rst three rings bigger than the remaining rings (Figures 1B and 2G).Mouth surrounded by six fi nger-shaped cephalic papillae (Figures 2G and  2H).The fi rst annul has the cephalic papillae, small amphids, pore-shaped, amphidial apertures small and circular positioned between second and thirdst annulies (Figure 2H).Stoma longer than broad, with two semicircles sclerotised and the telostoma with one movable tooth (Figure 1B).Oesophagus tripartite, indistinctly sclerotised at anterior end, with corpus subparallel-sided, expanded posteriorly, short isthmus, and basal bulb valvated (Figure 1B).Nerve ring situated around isthmus.Excretory pore posterior to anterior end of intestine.Intestine broad decreasing in width posteriorly.Vulva posterior, not protruding, with one lip more developed; vagina long and narrow (Figure 1A).Uterus single, directed anteriorly from vagina, and looping near anterior end of intestine, then posteriorly to posterior end of intestine, looping again and ascend anteriorly to level of vagina.Ovary single directed anteriorly to anterior end of intestine, near excretory pore.Eggs oval, with smooth shell, in apical view showing triangular section, with three wings, with dorsal wing and two lateroventrals wings (Figure 2D).Tail appendage short, conical and pointed, with anchorage-like structure at tip for grasping (Figures 1A, 2I, 2L, 2M and 2N).
the telostoma with one movable tooth, iv) amphids small pore shaped, v) oesophagus divided into three parts, anterior cylindrical corpus, isthmus distinct, and basal bulb valvated, vi) the nerve ring situated arrounded the isthmus, vii) the intestine broadest anteriorly, viii) eggs oval, smooth shell, in apical view show a triangular section, with three wings, the dorsal one and two lateroventrals, ix) males with one pair of preanal, and two pairs of postanal papillae, and the tail appendage short, conical and pointed, x) the female has in the top an structure of anchorage, like structure of grasp.Dale (4); by having the intestine of femaled taper posteriorly, and the nerve ring is located around the corpus.B. barryi can be distinguished from the new species by having the vulva to a distance of 17% of the length of the body, cuticle annulated only anteriorly, distinct rectal glands, the eggs with operculum, the male with three pairs of genital papillae, and two shallow constrictions in the tail.B. caucasica is distinguished by having mainly the male four pairs of genital papillae which two pairs are preanal and two pairs are postanal.B. cristovata can distinguished by having the stoma without tooth, with thick sclerotised walls forming three pairs of plates aligned in two rows with three pairs of plates, and the genital papillae arranged ventrolaterally in one pair of preanal, one pair of adanal and two pairs of postanal papillae.B. monandros can be characterized by the distance from vulva to anus about 7-17% of body length, three pairs of tail genital papillae, the cuticle annulated only anteriorly, tail without sharply linear point, corpus not broadest medially, fl ask shaped, the egg with operculum, and the spicule short (less than 15 μm).B. supellaimae is separated by having the distance from vulva to anus about 5% of body length, four pairs of tail papillae, tail conical, sharply linear point, and the nerve ring located around half corpus.B. tuapakae is different by the distance from vulva to anus about 7 % of body length, the three pairs of tail papillae, the cuticle annulated only anterior, the tail convex conoid, tending subulated near tip.Also we can compare our species with the type species, B. blattae Chitwood (4), since this one possesses the diagnostic characteristics of the genus, but differs from our new species by the female with the posterior part of the intestine broader than medial intestine, outstretched testis in the male, and the nerve ring situated around the isthmus, near base the corpus.

Remarks
Blatticola biannulata n. sp. is characterized by i) the females has the cuticle annulated up to the middle of the body, ii) the mouth opening subtriangular surrounded by 8 cephalic papillae, iii) the stoma short with two semicircles sclerotised and

Figure 1 -
Figure 1 -B.biannulata n. sp.A -Female; B -Anterior end of female; C -Male; D -Eggs: lateral view and anterior view; E -Anterior end of male; F -Posterior end of male, lateral view.Bars = 100 μm Source: Research data.

Figure 2 -
Figure 2 -B.biannulata n. sp.G -Anterior end of the female, fi nger shaped cephalic papillae.H -Front view of anterior end of female; I, L, M, N -Posterior end of female showing the structure of anchorage of the tail appendage; J -Posterior end of male with genital papillae.Bars = G, H, J, M: 10 μm; I, L, N: 20 μm Source: Research data.