ORIGINAL PAPER Strigeid parasites of Circus buffoni from Argentina, with the description of a new species of Parastrigea Szidat, 1928 Fabiana B. Drago1,2 & Verónica Núñez1,2 & Lía I. Lunaschi1,2 Received: 13 November 2017 /Accepted: 29 December 2017 /Published online: 16 January 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Studying the Helminthological Collection of Museo de La Plata (MLP-He), several specimens of digeneans, recovered parasit- izing a long-winged harrier, Circus buffoni (Accipitridae) from Buenos Aires Argentina, were analysed. The morphological and morphometric analysis of these specimens revealed the presence of two strigeid species, one of them new for science. Parastrigea buffoni n. sp. is characterised by a forebody differentiated in a retractile cephalic region with a large opening and a balloon-shaped collar region or collerette, suckers located in cephalic region, holdfast organ with well development dorsal and ventral lips that can emerge through opening, a claviform hindbody, a large copulatory bursa with muscular ring (Ringnapf) and a genital cone well delimited, crossed by a sinuous hermaphroditic duct with internal rugae. The euryxenous parasite, Strigea falconis brasiliana, is briefly described, parasitizing a new host. This is the first record of helminths parasitizing long-winged harrier. Keywords Strigeidae . Parastrigea buffoni n. sp. . Strigea falconis brasiliana .Circus buffoni . Accipitridae . Argentina Introduction Circus buffoni (Gmelin) (Accipitridae) commonly known as long-winged harrier is a bird of prey found in open fields, marshes, grasslands and savannas of the Neotropical region, from SW Colombia to the Guianas, Trinidad and Tobago, NE Brazil, E Bolivia and N and central region of Argentina and Chile (Thiollay 1994). The long-winged harrier is considered to be a least concern species (BirdLife International 2017). The knowledge about the helminth parasites is very important for the conservation of wildlife with implications in host pop- ulation biology (Youssefi et al. 2014). Until now, the helminth fauna of long-winged harriers has been unknown. Other two species of Circus Lacépède inhabit the Neotropical region, Circus cinereus Vieillot and Circus cyaneus (Linnaeus). In South America, the helminth fauna of these species is poorly known, only Ophiosoma microcephalum Szidat, 1928 (Digenea, Strigeidae) was reported parasitizing C. cyaneus (as Falco cyaneus) from Brazil (Szidat 1928). The aim of this study is to know the diversity of helminths in long-winged harriers from natural environments. Materials and methods A total of 69 digenean specimens stored in the Helminthological Collection ofMuseo de La Plata (MLP-He), La Plata, Argentina, were examined. They were recovered from a single specimen of Circus buffoni collected in Puán (37° 33′ S; 62° 46′W), Buenos Aires, Argentina, on April 1996. The specimens were stained with hydrochloric carmine, dehydrated and mounted in Canada balsam (Langeron 1942). Some specimens were removed from the slide and mounted between cover glasses in order to facilitate handling and observation. The terminal genitalia were studied in two specimens cleared in creosote. The measurements below are given in micrometres (μm) unless otherwise stated, as the range followed by mean in parentheses. Drawings were made with the aid of a drawing tube. The terms cephalic region and collerette of the forebody are used according to Dubois (1968). Cephalic region is the anterior region of the forebody containing the * Fabiana B. Drago fdrago@fcnym.unlp.edu.ar 1 División Zoología Invertebrados, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata (UNLP), Paseo del Bosque S/No. 1900, La Plata, Buenos Aires Province, Argentina 2 Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), La Plata, Argentina Parasitology Research (2018) 117:751–758 https://doi.org/10.1007/s00436-017-5746-x http://crossmark.crossref.org/dialog/?doi=10.1007/s00436-017-5746-x&domain=pdf mailto:fdrago@fcnym.unlp.edu.ar aperture and the collerette the posterior region containing the lateral expansions. Additionally, four of these specimens were deposited in the Collection of the Natural History Museum (NHM) in London, UK. Results The morphological and morphometric analysis of the studied specimens revealed the presence of two strigeid species, one of them new for science: Parastrigea buffoni n. sp. (22 spec- imens) and Strigea falconis brasiliana (47 specimens), a euryxenous parasite. Parastrigea buffoni n. sp. (Figs. 1 and 2, Table 1) Description (based on 18 specimens): body distinctly bipar- tite, 4.2–6.0 mm (5.314 mm) in total length (Fig. 1a). Tegument: smooth. Forebody globose: well differentiated in anterior cephalic region and posterior collar region or collerette, 1.4–2.1 mm (1.8 mm) long (Figs. 1b and 2). Cephalic region: cylindrical, retractile and with a large open- ing, 483–793 × 677–870 (623–783). Collerette: balloon- shaped, with prominent and bulbous lateral expansions, wider than cephalic region, 0.822–1.400 mm × 1.229–1.657 mm (1.192 × 1.488 mm). Hindbody claviform: longer than forebody, 2.628–4.0 mm × 0.914–1.371 mm (3.517 × 1.226 mm). Ratio of forebody length to hindbody length: 1:1.57–2.46 (1.96). Ratio of hindbody width to forebody width: 1:0.97–1.45 (1.25). Suckers: situated in cephalic re- gion. Oral sucker: weakly developed, 86–115 × 95–117 (97 × 107). Ventral sucker larger than oral sucker: 95–131 × 130–169 (113 × 146). Suckers width ratio: 1:1.22–1.78 (1.41) and distance between suckers: 88–136 (119). Pharynx: small, 69–100 × 69–107 (84 × 85); oesophagus: short, 49–87 (68) long; caeca: diverging anterior to ventral sucker, ending blind near the posterior region of the body. Holdfast organ: with well-developed dorsal and ventral lips, which can either emerge through the opening or stay indoors in the forebody. Dorsal lip: with two voluminous symmetrical expansions, oc- cupying almost the entire collerette and forming the space in which the cephalic region retracts. Proteolytic gland: well de- veloped, compact, 145–184 × 52–145 (172 × 101), situated in the middle of the collerette at 855–1354 (1173) from the an- terior end. Testes in tandem: multilobed, with digitiform lobes, situat- ed in the second third of the hindbody. Anterior testis: 387– 841 × 870–1286 (685 × 1118); posterior testis: 406–967 × 774–1257 (734 × 1115). Seminal vesicle: sinuous, postesticular. Copulatory bursa: large, delimited by moderate constriction, occupying 23–32% (28%) of the hindbody length; 735–1143 × 629–971 (997 × 892). Muscular ring (Ringnapf): present. Genital cone: well delimited, with strong muscular wall, 532–783 × 367–435 (658 × 401), crossed by a sinuous hermaphroditic duct with internal rugae (Fig. 1c). Genital atrium: shallow. Ovary: oval, reniform- or horseshoe-shaped, pretesticular, 328–493 × 440–919 (408 × 641). Pre-ovarian region: 677– 1402 (1052) occupying 25–41% (30%) of the hindbody length. Laurer’s canal: not seen. Ootype, Mehlis’ gland and vitelline reservoir in intertesticular region. Vitelline follicles: similar in size in both body segments. In forebody: with folli- cles disseminated in the body wall from the oral sucker, and in the dorsal lip of holdfast organ: forming two voluminous J- shaped masses occupying almost the entire collerette. In hindbody: with follicles occupying almost the entire width of the pre-ovarian region, extending ventrally to testes up to copulatory bursa. Uterus: thin-walled extending anteriorly from the ootype to the intersegmental constriction, and de- scending ventrally through the testicular region to joining with the ejaculatory duct at the base of the genital cone. Genital pore: terminal. Eggs: numerous, oval, 95–114 × 52–67 (102 × 61). Body length:egg length ratio 1:40–61 (1:52). Excretory vesicle and excretory pore: not seen. Taxonomic summary Type of host: Circus buffoni (Gmelin) (Accipitridae) (long- winged harrier) Type of locality: Puán, Buenos Aires Province, Argentina (37° 33′ S, 62° 46′ W) Date of collection: April 1996 Site of infection: Intestine Type of material: Holotype MLP-He 5801; paratypes MLP-He 5802 (six specimens) and NHM 2008.6.12.1 (four specimens) Voucher specimens: MLP-He 7443 (11 specimens) Etymology: The new species is named after the specific name of the host. Remarks The cosmopolitan genus Parastrigea Szidat, 1928 has been mainly reported parasitizing accipitrid, anatid, ardeid, ciconiid, falconid, jacanid, larid, podicipedid, recurvirostrid, threskiornithid and tytonid birds. Also, it was recovered in one Nile crocodile, probably as an accidental host (Dubois 1968). Six species are known in South America: Parastrigea brasiliana (Szidat, 1928), Parastrigea caballeroi Dubois, 1952, Parastrigea cincta (Brandes, 1888), Parastrigea diovadena Dubois and Macko, 1972, Parastrigea macrobursa Drago and Lunaschi, 2011 and Parastrigea robusta Szidat, 1928. Parastrigea brasiliana [syn. Apharyngostrigea brasiliana (Szidat, 1928)] has been found parasitizing exclusively ardeid 752 Parasitol Res (2018) 117:751–758 birds, Cochlearius cochlearius (Linnaeus), Nyctanassa violacea (Linnaeus), Butorides striatus (Linnaeus), Egretta thula (Molina), Tigrisoma lineatum (Boddaert) from Brazil and Ardea alba egretta Gmelin from Brazil and Venezuela (Fernandes et al. 2015). In Argentina, specimens were found parasitizing Ardea alba Linnaeus and Bubulcus ibis (Linnaeus) by Labriola and Suriano (1998), and A. a. egretta by Boero et al. (1972). All these specimens from Argentina were originally reported as A. brasiliana and later listed as Parastrigea brasiliana by Lunaschi et al. (2007). Finally, the specimens described by Labriola and Suriano (1998) were re- examined and transferred to Apharyngostrigea ardearum (Lutz, 1928); while the report of Boero et al. (1972) was regarded erroneous (see Drago and Lunaschi 2011a). In North America, P. brasiliana was reported in Ardea herodias Linnaeus from the USA (Gibson et al. 2005). Parastrigea brasiliana can be distinguished from the new species by hav- ing a cephalic region wider than the collerete, an undiscernible pharynx, a longer body size and hindbody, a larger ventral sucker and smaller ovary, copulatory bursa and eggs (Table 1). Parastrigea caballeroi has been reported parasitizing ciconiid birds, Jabiru mycteria (Lichtenstein) and Mycteria americana Linnaeus from Venezuela (Fernandes et al. 2015). This species mainly differs from P. buffoni n. sp. by having a forebody not divided and by the location of the ven- tral sucker, near the intersegmental constriction. It also differs in most metrical characters (Table 1). Parastrigea cincta has been recovered parasitizing Phimosus infuscatus berlepschi Hellmayr (Threskiornithidae) from Colombia, Ardea sp. (Ardeidae) andMicrastur gilvicollis Fig. 1 Parastrigea buffoni n. sp. from Circus buffoni. a Holotype, entire worm. b Dorsal view of forebody, collerette (Co), cephalic region (CR), dorsal lip of holdfast organ (DL), ventral lip of holdfast organ (VL). c Lateral view of terminal genitalia, genital cone (GC), hermaphroditic duct (HD), Ringnapf (R), seminal vesicle (SV), uterus (U) Parasitol Res (2018) 117:751–758 753 (Vieillot) (Falconidae) from Brazil and J. mycteria (Ciconiidae) from Venezuela (Fernandes et al. 2015). Also, it has been re- ported in Central andNorth America parasitizingPlatalea ajaja (Linnaeus) (Threskiornithidae), Falco sparverius sparverius Linnaeus (Falconidae) from Cuba and Eudocimus albus (Linnaeus) (Threskiornithidae) from Mexico (Dubois and Macko 1972; Ortega-Olivares et al. 2011). This species can be easily differentiated from P. buffoni n. sp. by having a forebody with a narrow opening, a sacciform hindbody and a copulatory bursa scarcely delimited and by the location of the ventral sucker, between the lateral expansions of the forebody vs. in the cephalic region. Also, it differs in most metrical char- acters (Table 1). Parastrigea diovadena was recovered parasitizing threskiornithid birds, Eudocimus ruber (Linnaeus) from Colombia (Dubois 1978). It is also reported in Central and North America parasitizing E. albus from Cuba, the USA and Mexico (Dubois and Macko 1972; Bush and Forrester 1976; Ortega-Olivares et al. 2011). This species mainly differs from P. buffoni n. sp. by having a forebody not divided, a copulatory bursa scarcely delimited and a large bilobed pro- teolytic gland. It also differs in most metrical characters (Table 1). Parastrigea macrobursa was described parasitizing Buteogallus urubitinga (Gmelin) (Accipitridae) from Argentina (Drago and Lunaschi 2011b). This species differs from P. buffoni n. sp. by having a forebody not divided, with lateral expansions lesser-developed, a copulatory bursa with- out muscular ring (Ringnapf), a proteolytic gland located at the base of the forebody and testes not lobed. It also differs in most metrical characters (Table 1). Parastrigea robusta was reported parasitizing Jacana ja- cana jacana (Jacanidae) from Brazil (Fernandes et al. 2015). It was also recovered in Tachybaptus ruficollis (Pallas) (Podicipedidae) from North America (Storer 2000) and in anatid and falconid birds from Eurasia (Dubois 1968). This species mainly differs from the new species by having a forebody with a small opening, a copulatory bursa poorly delimited, suckers situated in the collerette and an ovary lo- cated near the intersegmental constriction. It also differs in most metrical characters (Table 1). In Central and North America, other five species of Parastrigea occur, Parastrigea campanula Dubois and Rausch, 1950; Parastrigea mexicana Coil, 1957; Parastrigea ogchnocephala Dubois and Rausch, 1950; Parastrigea plataleae Hernández-Mena, García-Prieto and García-Varela, 2014 and Parastrigea tulipoides Miller and Harkema, 1965. Parastrigea campanula was recovered in Accipiter cooperii (Bonaparte) and Accipiter striatus Vieillot (Accipitridae) from the USA (Dubois and Rausch 1950; Gibson et al. 2005). This species mainly differs from the new species by having a campaniform copulatory bursa with- out muscular ring (Ringnapf) and a longer pre-ovarian region (occupying 49–50% of the hindbody length vs. 25–41%) (Dubois and Rausch 1950). Parastrigea mexicana has been reported parasitizing recurvirostrid birds, Himantopus mexicanus (Müller) from Cuba, Mexico and the USA and Recurvirostra americana Gmelin from Mexico, the USA and Canada (Coil 1957; Coil 1969; Dubois and Macko 1972; García and Canaris 1987; Hinojos and Canaris 1988; Edwards and Bush 1989). This species can be easily differentiated from P. buffoni n. sp. by having a forebody not divided with a small opening, an ovoid hindbody, a much shorter pre-ovarian region (occupying 14– 18% of the hindbody length vs. 25–41%), and a genital cone and a copulatory bursa weakly developed (Dubois and Macko 1972). Parastrigea ogchnocephala was reported in Accipiter gentilis (Linnaeus) and C. cyaneus (Accipitridae) from Alaska (Dubois and Rausch 1950, Dubois 1968). This species differs from the new species by having a shorter pre-ovarian region (occupying 20% of the hindbody length vs. 25–41%) and a voluminous genital cone (1050–1300 × 630–730 vs. 532–783 × 367–435) (Dubois and Rausch 1950). Parastrigea plataleae has been reported parasitizing P. ajaja (Threskiornithidae) from Mexico (Hernández-Mena et al. 2014). This species mainly differs from P. buffoni n. sp. by having a forebody with moderate lateral expansions, a cephalic region not retractile and poorly differentiated, a Fig. 2 Enlarged view of forebody of Parastrigea buffoni n. sp. from Circus buffoni 754 Parasitol Res (2018) 117:751–758 Ta bl e 1 C om pa ra tiv e m ea su re m en ts of P ar as tr ig ea bu ffo ni n. sp .w ith So ut h A m er ic an P ar as tr ig ea sp ec ie s P. bu ffo ni n. sp . P. br as ili an a P. ca ba lle ro i P. ci nc ta P. di ov ad en a P. m ac ro bu rs a P. ro bu st a B L (m m ) 4. 2– 6. 0 U p to 7. 6 U p to 6. 4 U p to 7. 5 2– 3. 7 1. 18 9– 2. 11 7 U p to 3. 7 FB (m m ) 1. 4– 2. 1 × 1. 3– 1. 7 1. 0– 1. 65 × 0. 71 –1 .0 1. 20 –1 .7 9 × 1. 06 – 0. 8– 1. 47 × 0. 66 –1 .1 3 0. 44 –0 .7 8 × 0. 35 –0 .6 4 1– 1. 25 × 0. 9– 1. 5 H B (m m ) 2. 6– 4 × 0. 9– 1. 2 4– 6 × 0. 48 –0 .9 2 3. 9– 4. 5 × 1. 06 –1 .2 0 – 1. 29 –2 .2 4 × 0. 7– 1. 1 0. 75 –1 .5 × 0. 39 –0 .6 6 1. 7– 2. 4 × 0. 9– 1. 4 H B /F B 1. 6– 2. 5 3. 1– 4. 8 2. 5 – 1. 4– 1. 8 1. 7– 3. 1 1. 7– 1. 9* * O S 86 –1 15 × 95 –1 17 80 –9 6 × 10 0– 12 0 19 0– 20 9 × 15 9– 19 0 80 –1 10 × 11 5– 13 0 70 –1 00 × 95 –1 10 76 –8 7 × 64 –9 9 10 0– 13 0 × 10 0– 13 5 V S 95 –1 31 × 13 0– 16 9 14 5– 16 2 × 17 5– 20 0 28 5– 31 2 × 27 4– 30 8 13 5– 15 0 × 14 5– 16 5 11 5– 15 0 × 11 5– 16 0 82 –1 07 × 60 –1 50 13 0– 17 0 × 10 0– 15 0 Ph 67 –8 8 × 79 –9 3 U nd is ce rn ib le 13 7– 14 4 × 95 –9 9 95 –1 20 × 80 –1 10 42 –5 5 in di am . 44 –6 0 × 39 –6 0 90 –1 00 × 65 –1 00 PG 14 5– 18 4 × 52 –1 45 – – 29 0– 31 0 × 14 5– 16 5 18 0– 20 0 × 24 0– 30 0 (e ac h lo be ) 64 –8 3 × 60 –7 6 – O 32 8– 49 3 × 44 0– 91 9 21 0– 26 0 × 34 0– 36 0 26 6– 28 9 × 59 8– 68 1 45 0– 66 0 × 77 0– 95 0 17 0– 32 0 × 23 0– 45 0 69 –1 31 × 10 9– 19 0 – A T 38 7– 84 1 × 87 0– 12 86 50 0– 74 0 × 64 0– 82 0 64 7– 79 7 × 83 0– 10 62 56 0– 77 0 × 14 70 –1 57 0 38 0– 42 0 × 67 0– 82 0 97 –1 55 × 18 8– 26 2 – PT 40 6– 96 7 × 77 4– 12 57 55 0– 74 0 × 64 0– 85 0 68 1– 84 7 × 76 4– 12 45 80 0– 87 5 × 13 00 –1 57 0 40 0– 45 0 × 69 0– 87 0 10 2– 21 3 × 19 3– 30 4 – C B 73 5– 12 57 × 62 9– 97 1 40 0– 60 0 – – – 29 0– 64 8 × 28 0– 53 2 – G C 53 2– 78 3 × 36 7– 43 5 – 28 9 × 28 9– 34 2* – – 11 7– 17 9 × 10 7– 17 6 50 0 × 15 5– 21 0 E gg s 95 –1 14 × 52 –6 7 84 –9 4 × 53 –6 3 87 –9 1 × 41 –5 3 80 –1 20 × 50 –7 0 90 –1 00 × 62 –6 8 92 –1 43 × 57 –7 7 90 –1 15 × 40 –7 0 S ou rc e Pr es en ts tu dy D ub oi s (1 96 8) D ub oi s (1 96 8) D ub oi s an d M ac ko (1 97 2) D ub oi s an d M ac ko (1 97 2) D ra go an d L un as ch i( 20 11 b) D ub oi s (1 96 8) AT an te ri or te st is ,B L bo dy le ng th ,C B co pu la to ry bu rs a, F B fo re bo dy ,G C ge ni ta lc on e, H B hi nd bo dy ,H B /F B hi nd bo dy le ng th /f or eb od y le ng th ,O ov ar y, O S or al su ck er ,P h ph ar yn x, P G pr ot eo ly tic gl an d, P T po st er io r te st is ,V S ve nt ra ls uc ke r *I nv ag in at ed ;* *C al cu la te d fr om or ig in al de sc ri pt io ns Parasitol Res (2018) 117:751–758 755 proteolytic gland situated near the intersegmental constriction and a campaniform copulatory bursa wider than longer. Parastrigea tulipoides, reported in Buteo lineatus (Gmelin) and Buteo jamaicensis (Gmelin) (Accipitridae) from the USA (Dubois 1968; Gibson et al. 2005), can be easily differentiated from the new species by having a forebody with lateral expan- sions poorly developed, a proteolytic gland situated near the intersegmental constriction, a long pre-ovarian region, occu- pying more than 50% of the hindbody and a shorter genital cone (200–240 × 150–210 vs. 532–783 × 367–435). Based on all these morphological and morphometrical dif- ferences, a new species Parastrigea buffoni n. sp. is proposed. Strigea falconis brasiliana Szidat, 1929 (Fig. 3) Measurements (based on ten specimens): Body distinctly bi- partite, 2057–3285 (2595.5) in total length. Forebody: 677– 1000 × 740–985 (861 × 862). Hindbody: subcylindrical, with- out a true neck region or BHalstei^, 1371–2286 × 648–1000 (1734 × 877). Ratio of hindbody length to forebody length: 1:1.7–2.4 (2). Oral sucker: 68–126 × 89–169 (105 × 137.5), ventral sucker: 101–212.5 × 121–266 (157–209). Suckers width ratio: 1.1–2 (1.5). Pharynx: 75–140 × 58–124 (102 × 93). Proteolytic gland: 109–193 × 169–270 (142 × 215). Testes in tandem—anterior testis: 198–541 × 261–967 (394 × 566), posterior testis: 169–580 × 285–880 (392 × 566). Pre-ovarian region: occupying 12–26 (21) % of the hindbody. Ovary: 179–280 × 203–493 (223 × 386). Vitellarium follicular in the forebody: reaching pharyngeal region; in the hindbody: occupying its whole width in the pre-ovarian region and extending dorsally up to the copulatory bursa. Vitelline reservoir: intertesticular. Uterus: with 12–50 eggs, 93–117 × 57–74 (105 × 66.5). Copulatory bursa: 295– 561 × 257–493 (388 × 426), with muscular ring (Ringnapf) and genital cone 174–241.5 × 203–270 (204–252). Taxonomic summary Host: Circus buffoni (Gmelin) (Accipitridae) (long-winged harrier) Locality: Puán, Buenos Aires Province, Argentina (37° 33′ S, 62° 46′ W) Date of collection: April 1996 Site of infection: Intestine Voucher specimens: MLP-He 5895 (47 specimens) Remarks This strigeid has a broad spectrum of definitive hosts, including raptors, scavenging and aquatic birds (Lunaschi and Drago 2013). Particularly in Argentina, it was reported parasitizing Rupornis magnirostris (Gmelin), Milvago chimachima (Vieillot), Caracara plancus (Miller), Phalacrocorax brasilianus (Gmelin) and Asio clamator (Vieillot) (Lunaschi and Drago 2006; Drago et al. 2011, 2014, 2015). The finding of this strigeid species in C. buffoni represents a new host record. Discussion Helminths of wild birds have been less studied than other vertebrates, mainly because the birds are one of the most char- ismatic and protected groups. Then, it is difficult to obtain a sufficient number of these hosts because many are protected by national and international laws (Perez Ponce de León et al. 2011). Much of the information available on parasites in wild birds comes from studies carried out in birds that died acci- dentally or by nature causes. In these cases, the hosts or their viscera are often fixed in formalin or frozen; thus, the parasites can contract or some structures are lost making taxonomic identification difficult. Therefore, the majority of parasites of wild birds have yet to be described taxonomically (Wobeser 2008). Other important sources of information for taxonomic studies on helminths of birds are the helminthologicalFig. 3 Strigea falconis brasiliana from Circus buffoni 756 Parasitol Res (2018) 117:751–758 collections, which preserve information on spatial and tempo- ral biodiversity. Collections also can provide information about the habits and diet of birds. The large number of strigeids (22P. buffoni n. sp. and 47 S. f. brasiliana) found in a single specimen of C. buffoni could be related to the feeding habits of these birds and the intermediate hosts of these digeneans. The diet of the long-winged harrier mainly consists of birds, mammals, reptiles and amphibians (Thiollay 1994). Research conducted in Buenos Aires Province, shows that birds are the preferred prey (Tinamidae, Threskiornithidae, Anatidae, Rallidae, Columbidae, Furnariidae, Mimidae, Passerellidae, Thraupidae, Icteridae, Passeridae, Fringillidae), followed by mammals (Leporidae, Cricetidae and Didelphidae) and insects (Coleoptera and Odonata) (Bó et al. 1996). The known life cycle of Parastrigea spp. includes metacercariae of ‘tetracotyle’ type in anurans as intermediate hosts, while in Strigea spp. involves mesocercariae in anurans and metacercariae of ‘tetracotyle’ type in amphibians, reptiles, birds and mammals (Niewiadomska 2002). Particularly in Strigea falconis falconis (Viborg, 1795), mesocercariae were reported in several species of tadpoles and adults of anurans, and metacercariae were mainly recovered parasitizing a broad spectrum of birds Ciconiiformes, Podicipediformes, Ralliformes, Pelecaniformes, Anseriformes, Charadriiformes, Falconiformes, Coraciiformes, Galliformes, Columbiformes, Slrigiformes, Piciformes and Passeriformes (Dubois 1968). The higher intensity of S. f. brasiliana can be associated with the preferred preys of the host (birds), while the moderate intensity of P. buffoni n. sp. can be related with the occasional consumption of amphibians. Acknowledgements We thank Sonia Fontana for the revision of the English version. Funding This study was funded by the Universidad Nacional de La Plata (UNLP) (11/N751) and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC) (Res. No. 048/16). 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Asian Pac J Trop Biomed 4(Suppl 1):S143–S147. https://doi.org/10.12980/APJTB.4. 2014C1205 758 Parasitol Res (2018) 117:751–758 https://doi.org/10.11646/zootaxa.1403.1.1 https://doi.org/10.11646/zootaxa.1403.1.1 https://doi.org/10.11646/zootaxa.1106.1.2 https://doi.org/10.14411/fp.2013.034 https://doi.org/10.1079/9780851995472.0231 https://doi.org/10.1079/9780851995472.0231 https://doi.org/10.5772/25011 https://doi.org/10.1002/9780813804620.ch1 https://doi.org/10.1002/9780813804620.ch1 https://doi.org/10.12980/APJTB.4.2014C1205 https://doi.org/10.12980/APJTB.4.2014C1205 Strigeid parasites of Circus buffoni from Argentina, with the description of a new species of Parastrigea Szidat, 1928 Abstract Introduction Materials and methods Results Parastrigea buffoni n. sp. (Figs. 1 and 2, Table�1) Taxonomic summary Remarks Strigea falconis brasiliana Szidat, 1929 (Fig. 3) Taxonomic summary Remarks Discussion References