taxonID	type	description	language	source
03B5878CFF97DA3A7D58010CFB05F9B6.taxon	discussion	Remarks. The two names Pseudoacanthocephalidae and Pseudoacanthocephalus were introduced without diagnoses (Petrochenko 1956: 160) and were nomina nuda at that time. These names became available when Petrochenko (1958) provided a detailed diagnosis of the family and the genus. Therefore, the date of publication of these names is 1958 instead of 1956.	en	Kajihara, Yuki Kita Masato Nitta Harue Abe Shigen Kaburagi Takeshi Fujita Kenji Toyota Yusuke Kondo Hiroshi (2025): A new species of Pseudoacanthocephalus (Acanthocephala: Pseudoacanthocephalidae) from Sado Island, Japan, with a report of its accidental occurrence in a marine elasmobranch. Folia Parasitologica (028) 72: 1-11, DOI: 10.14411/fp.2025.028, URL: https://doi.org/10.14411/fp.2025.028
03B5878CFF97DA3E7D5802ECFEE9FA36.taxon	description	urn: lsid: zoobank. org: act: 5068 EFBC-DD 37 - 405 E-A 337 - 17 A 4 D 1 CA 57 F 9 H o l o t y p e: ICHUM 8962 - 1 (male). P a r a t y p e: ICHUM 8962 (2 males and 1 female), 8963 (1 male and 1 female), 8964 - 1 (1 female), 8965 (1 male), 8967 (1 male and 1 female), 8968 (1 male and 1 female), 8970 (1 male), and 8974 (1 female). T y p e l o c a l i t y: Ishina (38.2111 N, 138.3911 E) (Sado, Niigata, Japan). O t h e r l o c a l i t i e s: Bunagataira (Sado, Japan); Hannokidate (Sado, Japan); Katagami (Sado, Japan); Minami-Katabe (Sado, Japan); off Tassha (Sado, Japan: accidental); Ohkura-Shiraba (Sado, Japan); Sugiike (Sado, Japan). T y p e h o s t: Rana ornativentris Werner (Ranidae). O t h e r h o s t s: Zhangixalus arboreus (Okada et Kawano) (Rhacophoridae); Scyliorhinus torazame (Tanaka) (Scyliorhinidae: accidental). D e s c r i p t i o n: General (n = 14, including SEM specimen). Trunk cylindrical, aspinose, slightly swollen in anterior one-fourth to middle. Proboscis cylindrical to conical, armed with 18 – 19 longitudinal rows (n = 8) of 6 – 7 hooks (n = 3) (Figs. 2 B, C, 3 B). Size of hooks gradually increasing toward middle of row: female hooks relatively larger than male. Proboscis receptacle short, double-walled. Cephalic ganglion positioned middle of proboscis receptacle. Lemnisci longer than receptacle, broad. Male (n = 7). Trunk cylindrical, 4.6 – 7.4 mm (average 6.4 mm) × 1.1 – 1.3 mm (1.3 mm) (Fig. 2 A). Proboscis cylindrical to conical, 500 – 550 (530) (n = 2) × 280 – 400 (350) (n = 5) (Fig. 2 A – C). Size of hooks gradually increasing toward middle of row: hook blade 30 – 40 (40) in anterior first and second hooks, 50 – 60 (54) in third hook, 50 – 70 (63) in fourth hook; 60 – 70 (67) in fifth hook; and 40 – 70 (55) in sixth hook; hook root 10 – 20 (16) in first and second hooks; 20 – 30 (27) in third hook; 20 – 40 (35) in fourth hook; 30 – 40 (40) in fifth hook; and 20 – 30 (31) in sixth hook. Proboscis receptacle short, double-walled, 400 – 770 (559) × 230 – 370 (291) (Fig. 2 A). Lemnisci longer than receptacle, broad, 600 – 1,130 (843) in length (Fig. 2 A). Testes globular to oval, tandem (Fig. 2 A). Anterior testis 380 – 630 (483) × 280 – 540 (430). Posterior testis 360 – 650 (510) × 240 – 470 (388). Cement glands six, clustered, filiform to fusiform (Figs. 2 A, 3 D). Saefftigen’s pouch 400 – 680 (558) in length. Copulatory bursa opening subterminally, 440 – 540 (497) (n = 2) in width (Fig. 2 B). Female (n = 6). Trunk cylindrical, 5.1 – 9.7 mm (7.9 mm) × 1.1 – 1.3 mm (1.3 mm) (Fig. 2 D). Proboscis cylindrical, 260 – 430 (336) (n = 5) in width (Fig. 3 D) (not fully extended). Size of hooks gradually increasing toward middle of row: hook blade 50 – 70 (60) in third hook, 60 – 80 (74) in fourth hook; 70 – 80 (77) in fifth hook; and 50 – 70 (61) in sixth hook; hook root 20 – 30 (25) in third hook; 30 – 40 (36) in fourth hook; 30 – 40 (40) in fifth hook; and 20 – 40 (32) in sixth hook. Proboscis receptacle short, double-walled, 290 – 1,000 (561) × 190 – 340 (248) (Fig. 2 D). Lemnisci longer than receptacle, broad, 560 – 820 (735) (n = 3) in length (Fig. 2 D). Uterus 940 – 1,100 (1,014) in length (Fig. 2 E). Vaginal sphincter single. Eggs elliptical with polar prolongation, 80 – 100 (96) (n = 10) in length (Figs. 2 F, 3 C).	en	Kajihara, Yuki Kita Masato Nitta Harue Abe Shigen Kaburagi Takeshi Fujita Kenji Toyota Yusuke Kondo Hiroshi (2025): A new species of Pseudoacanthocephalus (Acanthocephala: Pseudoacanthocephalidae) from Sado Island, Japan, with a report of its accidental occurrence in a marine elasmobranch. Folia Parasitologica (028) 72: 1-11, DOI: 10.14411/fp.2025.028, URL: https://doi.org/10.14411/fp.2025.028
03B5878CFF97DA3E7D5802ECFEE9FA36.taxon	etymology	Etymology. The new specific name is an adjective, after the type locality, Sado Island.	en	Kajihara, Yuki Kita Masato Nitta Harue Abe Shigen Kaburagi Takeshi Fujita Kenji Toyota Yusuke Kondo Hiroshi (2025): A new species of Pseudoacanthocephalus (Acanthocephala: Pseudoacanthocephalidae) from Sado Island, Japan, with a report of its accidental occurrence in a marine elasmobranch. Folia Parasitologica (028) 72: 1-11, DOI: 10.14411/fp.2025.028, URL: https://doi.org/10.14411/fp.2025.028
03B5878CFF97DA3E7D5802ECFEE9FA36.taxon	discussion	Remarks. Based on the key to species provided by Zhao et al. (2024) and the original descriptions of all congeners, the new species is distinguished within the genus by (i) the arrangement of proboscis hooks, (ii) the number of cement glands, and (iii) the presence of eggs with polar prolongation (Table 3). We can distinguish Pseudoacanthocephalus sadoensis sp. n. from other congeners by the presence of polar prolongation in the eggs, except P. caucasicus (Petrochenko, 1953), P. lucidus and P. toshimai. These three species differ from P. sadoensis sp. n. in the proboscis hook arrangement: P. sadoensis sp. n. possesses 18 – 19 hook rows, compared to 12 – 16 rows in P. lucidus and P. toshimai, and 22 – 24 in P. caucasicus. In addition, we found that the proboscis hooks in females were relatively larger than those in males. Such sexual dimorphism has not been observed in previous studies of P. lucidus or P. toshimai (Van Cleave 1925, Nakao 2016), the closest relatives of P. sadoensis sp. n.	en	Kajihara, Yuki Kita Masato Nitta Harue Abe Shigen Kaburagi Takeshi Fujita Kenji Toyota Yusuke Kondo Hiroshi (2025): A new species of Pseudoacanthocephalus (Acanthocephala: Pseudoacanthocephalidae) from Sado Island, Japan, with a report of its accidental occurrence in a marine elasmobranch. Folia Parasitologica (028) 72: 1-11, DOI: 10.14411/fp.2025.028, URL: https://doi.org/10.14411/fp.2025.028
