image/svg+xml153New species of UrocleidoidesNeotropical Helminthology (Lima). Vol. 17, Nº2, jul - dic 2023Neotropical HelminthologyNeotropical Helminthology, 2023, vol. 17 (2), 153-163ORIGINAL ARTICLE / ARTÍCULO ORIGINALMORPHOMETRIC AND CYTOGENETIC DESCRIPTION OF BLATTICOLA CHYDAEUS SP. N. (NEMATODA, THELASTOMATIDAE), A PARASITE OF ANUROGRYLLUS MUTICUS(DE GEER, 1773) (ORTHOPTERA, GRYLLIDAE) IN ARGENTINADESCRIPCIÓN MORFOMÉTRICA Y CITOGENÉTICA DE BLATTICOLA CHYDAEUSSP. N. (NEMATODA, THELASTOMATIDAE), UN PARÁSITO DE ANUROGRYLLUS MUTICUS(DE GEER, 1773) (ORTHOPTERA, GRYLLIDAE) EN ARGENTINANora B. Camino1,2,3*; Carolina Casanovas1,2& Sergio Rodríguez Gil1,4ISSN Versión Impresa 2218-6425 ISSN Versión Electrónica 1995-1403DOI: https://dx.doi.org/10.24039/rnh20231721655Volume 17, Number 2 (jul - dec) 2023Este artículo es publicado por la revista Neotropical Helminthology de la Facultad de Ciencias Naturales y Matemática, Universidad Nacional Federico Villarreal, Lima, Perú auspiciado por la Asociación Peruana de Helmintología e Invertebrados Af nes (APHIA). Este es un artículo de acceso abierto, distribuido bajo los términos de la licencia Creative Commons Atribución 4.0 Internacional (CC BY 4.0) [https:// creativecommons.org/licenses/by/4.0/deed.es] que permite el uso, distribución y reproducción en cualquier medio, siempre que la obra original sea debidamente citada de su fuente original.Centro de Estudios Parasitológicos y de Vectores, CEPAVE, Argentina.2 Universidad Nacional de La Plata, UNLP, Facultad de Ciencias Naturales y Museo, Argentina.3 Investigador CIC, Comisión de Investigaciones Científ cas de la provincia de Buenos Aires, CIC, Argentina.4 Consejo Nacional de Investigaciones Científ cas y Técnicas, CONICET, Argentina.* Corresponding author: nemainst@cepave.edu.ar Nora B. Camino: https://orcid.org/0000-0003-4910-3986Carolina Casanovas: https://orcid.org/0009-0003-9774-6078Sergio Rodríguez-Gil: https://orcid.org/0000-0003-4608-1961 ABSTRACTBlatticola chydaeusn. sp. (Nematoda, T elastomatidae), parasitizing Anurogryllus muticus(De Geer, 1773) (Orthoptera, Gryllidae) in Argentina is morphometric and cytogenetic described. It is characterized by the female with cuticle annulated up to the middle of the body, the mouth surrounded by eight cephalic papillae, the stoma short with two plates and one tooth, the amphid pore shaped, the esophagus divided into three parts, anterior cylindrical corpus, isthmus distinct, and basal bulb valvated, the excretory pore located posterior to the basal bulb, the nerve ring situated at the beginning of the esophagic isthmus, the intestine broadest anteriorly, the egg oval, smooth shell, in apical view show a triangular section. T e tail appendage is short and conic and presents anal alae. T e vulva is protruding, the vagina is long and posterior. T e male has one preanal papilla, one simple papilla, and one pair of postanal papillae. One spicule, short and simple, without gubernaculum. T e tail appendage is short, conic, and pointed. T e cytogenetic study revealed very small acrocentric chromosomes, this new species shows 3 and 3+X bivalent chromosomes, the sexual determination is not given by haplodiploidy, the sexual chromosome was assumed to be X.Keywords: Blatticola chydaeus sp. n. – T elastomatidae – cricket – morphometric – cytogenetic – Argentina
image/svg+xml154Neotropical Helminthology (Lima). Vol. 17, Nº2, jul - dic 2023Camino et al.RESUMENBlatticola chydaeusn. sp. (Nematoda, Telastomatidae), es un parásito de Anurogryllus muticus(De Geer, 1773) (Orthoptera, Gryllidae) en Argentina, se describe al parásito morfométrica y citognéticamente. Se caracteriza porque la hembra posee una cutícula anillada hasta la mitad del cuerpo, boca rodeada por ocho papilas cefálicas, estoma corto con dos placas y un diente, anfdio piriforme, esófago dividido en tres partes, corpus anterior, istmo y bulbo basal valvado. El poro excretor ubicado posterior al bulbo basal, el anillo nervioso situado al comienzo del istmo esofágico, el intestino más ancho anteriormente, huevos ovales de cáscara lisa en vista apical muestran una sección triangular. Apéndice caudal corto y cónico, con ala anal. Vulva protuberante, vagina larga y posterior. El macho tiene una papila preanal, una papila simple y un par de papilas postanales. Una espícula, corta y sencilla, sin gubernáculo. El apéndice caudal corto, cónico y puntiagudo. El estudio citogenético reveló cromosomas acrocéntricos muy pequeños. Esta nueva especie muestra cromosomas bivalentes 3 y 3 + X, la determinación sexual no se da por haplodiploidía, el cromosoma sexual es X. Palabras claves: Blatticola chydaeus n. sp. – Telastomatidae – grillo – morfometría – citogenética – ArgentinaINTRODUCTIONDuring the day, Anurogryllus muticus(De Geer, 1773) crickets stay in the galleries they make under the ground, feeding on grass roots, and on warm nights, they often leave their caves to feed on the surface. Te most serious damage caused by crickets is to the grass, where they can destroy the root system. Due to the signifcant loss of root mass, a yellow spot can be observed (Rusconi, 2007). Tat is why it is necessary to fnd some biocontrol agent, such as nematodos, which promise to be efective. It is necessary to search for some biocontrol agent, such as nematodes. Nematodes of the family Telastomatidae, which belongs to the genus Blatticola, were found during a feld survey. Te genus BlatticolaSchwenk, 1926, who was designated for B. blatticolaas its type species. In 1932, Chitwood considered this species a synonym of B. blattae(Graefe, 1860). Te confusion in the taxonomy of the genus and type species was clarifed by Dale in 1966. Earlier emended diagnosis of the genus was modifed (Adamson & van Waerebeke, 1992) to accommodate the species described by Chitwood (1932) in a revision of the thelastomatid group. Te genus BlattellicolaBasir, 1940 and BlatellicoloidesFarooqui, 1966 agree with Blatticolain 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 feld surveys on agricultural pests in Argentinian areas of La Plata, Buenos Aires province, we found cricket nymphs parasitized by species of this thelastomatid group. Achinelly & Camino (2007) described a new species, Blatticola cristovata, and then Camino & Schargorodsky (2009) described B. biannulata. Tese records represent the frst and second reports of parasitized crickets in Argentina. Rodriguez-Gil et al.(2017) described the morphology of another new species of the genus and carried out a cytogenetic study on Blatticola ancoracauda, also from Argentinian crickets. In the present study, we found a new species of the genus Blatticola. MATERIALS AND METHODSTwenty-fve crickets were collected from the lawn in 66thAv., between 1st Av. (34° 55’ 13.318’’ S, 57° 55’ 42.994’’ W) and 2ndSt. (34° 55’ 16.612’’ S, 57° 55’ 46.432’’ W) in La Plata, Buenos Aires province, from October 2017 to March 2018. Considering the biological cycle of the crickets, were captured during the warm months of the Southern Hemisphere, in coincidence with their reproductive season. Te adults were found from October to December, and between January and March, mostly nymphs. Te crickets were captured using a tensioactive solution (detergent and water) that causes an obstruction in their respiratory tract, making them come out of the subterranean galleries they inhabit. Te methodology followed consisted frstly on the identifcation of the holes that were compatible the cricket’s caves. Ten, each hole was flled with the tensioactive solution until the crickets came out. Every single insect was recollected in a jar and immediately carried to the laboratory to execute its dissection by previously refrigerating it to asleep. If the dissection couldn’t be done on the same day of the recollection, the insects were kept in the refrigerator at -4°C until the next day. Te dissection was carried out under stereoscopic binocular lens, with the help of dissection needles, tweezers, a Westcott pair of scissors and under immersion in physiological solution. Te incision begins at the anus, continuing by the cricket pleura until
image/svg+xml155Morphometric and cytogenetic description of Blatticola chydaeusNeotropical Helminthology (Lima). Vol. 17, Nº2, jul - dic 2023the thoracic region, then transversely by the sterno and it fnishes by the other pleura, opening a window from where the mid and posterior gut was retired. Te cricket was kept in an 80% ethyl alcohol solution for posterior taxonomic identifcation. Later on, the gut was opened side to side, caring not to hurt the potential parasites, to make evident their presence. Te nematodes were extracted and fxed in diferent solutions for its posterior treatment, depending on the study to be carried out. Each treatment is described below.Morphometric and systematic analysis of nematodesFor the morphological studies and systematic analysis TAF (formalin 7%, triethanolamine 2 % and distilled water 91%) was used as fxer (Courtney et al.,1955). 20 nematodes were fxed. Te nematodes were killed by placing them in distilled water at 60 °C for 2 minutes. Ten they were moved to a 50% TAF solution in water for 48 hours, and fnally they were placed in pure TAF. Fixed specimens were photographed with a camera mounted on a Zeiss compound microscope. All measurements are in µm, and presented as the mean and standard deviation, with ranges in parenthesis.Cytogenetic analysisFor cytogenetic studies, 139 crickets were analyzed, 22 of which were parasitized with at least one nematode. 16 nematodes adults were selected and placed in distilled water for 30 minutes and then fxed in regular Carnoy’s solution (six parts pure ethyl alcohol, three parts chloroform and one-part acetic acid) and in a modifed one (six parts pure ethyl alcohol, one-part chloroform and one part acetic acid). Te cytogenetic preparations were made using the squash technique and stained with 45% acetic orcein (Adamson, 1981; Lacadena, 1996; Rodríguez-Gil et al., 2007). Te representative cells of each stage were photographed with an Olympus microscope with digital camera DP 71, using the program DP Controller 3.3.1.292, the images were processed with the programs Pixillion V Demo 6.08, and the karyotypes were done with DRAWID (Kirov et al., 2017).Te TCL, which represents the total length of a haploid cell, was obtained summing the average of each one of the homologous chromosomes.Ethic aspect: Te ethical biosafety standards established for laboratory animals and good animal experimentation practices were followed.RESULTSWe recognized our new species belonging to the genus BlatticolaSchwenk, 1926, which is characterized by the female with cuticle annulated up to the middle of the body, the mouth opening subtriangular surrounded by eight cephalic papillae, the stoma short and telostoma with two plates and one tooth in the telorhabdion (Fig. 1 A), the amphid small pore shaped, the oesophagus divided into three parts, anterior cylindrical corpus, isthmus distinct, and basal bulb valvated (Fig. 1 B), the excretory pore located posterior to basal bulb, the nerve ring situated at the beginning of the esophagic isthmus, the intestine broadest anteriorly, the egg oval, smooth shell, in apical view show a triangular section. Te basal bulb is muscular and strong, and is inserted into the frst part of the intestine. Te tail appendage is short and conic, and presents anal alae (Fig. 1C). Te vulva is protruding, the vagina is long and posterior with V = 70% (Fig. 1D). Te male has one preanal papilla, one simple papilla and one pair of postanal papillae (Fig. 2B). It also has a spicule, short and simple, without gubernaculum (Fig. 2A). Te tail appendage is short, conic and pointed.Table 1. Blatticola chydaeusn. sp. Mean and standard deviation of the diferent measurements, with ranges (minimum and maximum) µm in parenthesis.Total length5,500 ± 368.62 (5,200 – 6,300)1,125 ± 320 (1,000 – 1,800)Diameter of head at level of cephalic papillae24 ± 5.2 (20-32)14.28 ± 4.6 (11-20)Stoma length16 ± 0.6 (15-17)5.2 ± 0.2 (5- 6)Stoma width8.8 ± 0.2 (8-9)3.5 ± 0.2 (3-4)Width of body at level of nerve ring164.70 ± 42.1 (122-210)40.22 ± 3.8 (38-45)Maximum body diameter282.35 ± 45.9 (222-318)47.36 ± 2.2 (46-50)Width of body at level of posterior end 129.41 ± 13.6 (116-142)40 ± 3.8 (36-42)Width of body at level of vulva241.17 ± 33.9 (220-290)---Distance anterior end to nerve ring 358.82 ± 45.4 (320-410)125.71 ± 18.6 (109-145)(Continued Table 1)
image/svg+xml156Neotropical Helminthology (Lima). Vol. 17, Nº2, jul - dic 2023Camino et al.Oesophagus length620 ± 45.6 (550-660)194.98 ± 68.3 (120-260)Distance from anterior end to excretory pore1,400 ± 305 (1,000 – 1,600)337.14 ± 642.5 (290-382)Vagina length300 ± 60.9 (260-355)---Vagina width47.05 ± 4.3 (42-52)---V (distance anterior end to vulva/body length x 100)68.98 ± 1.6 % (68-71)---Spicule length ---32.35 ± 2.8 (29-35)Spicule width---4.41 ± 0.6 (4-5)Length of eggs88.23 ± 2.6 (85-90)---Width of eggs41.17 ± 1.5 (40-43)---Tail appendage length45.29 ± 2.8 (42-48)26.47 ± 1.02 (25-27)(Continued Table 1)ABCDFigure 1. Blatticola chydaeus n. sp. Te female. A) Anterior end. B) Oesophagus and anterior end of intestine. C) Tail appendage. D) Posterior end of the body showing the vulva. Bars = A, C: 100 µm; B, D: 200 µm.
image/svg+xml157Morphometric and cytogenetic description of Blatticola chydaeusNeotropical Helminthology (Lima). Vol. 17, Nº2, jul - dic 2023