Acanthobothrium sinaloaensis, Zaragoza-Tapia & Pulido-Flores & Monks, 2020

Zaragoza-Tapia, Francisco, Pulido-Flores, Griselda & Monks, Scott, 2020, Three new species of Acanthobothrium Blanchard, 1848 (Cestoda: Onchoproteocephalidea) in Stingrays (Dasyatidae) from the Pacific coast in Mexico, Zootaxa 4766 (1), pp. 139-172 : 164-165

Acanthobothrium sinaloaensis n. sp.

( Figs. 3 , 22–30 )

urn:lsid:zoobank.org:act:835CD0CA-6412-444D-8322-B5CBCB9FE584

Type host: Hypanus longus ( Myliobatiformes : Dasyatidae ).

Type locality: La Puntilla, Mazatlán, Sinaloa, Mexico.

Site of infection: Spiral intestine.

Deposited material: Holotype ( CNHE–11257 ) , 6 paratypes (CNHE–11258), and 5 paratypes (HWML– 216262).

ZooBank registration: The Life Science Identifier (LSID) urn:lsid:zoobank.org:act:835CD0CA-6412-444D-8322-B5CBCB9FE584

Etymology: The species name refers to the state of Sinaloa, México where the type specimen was collected.

Description. Based on whole mounts of 11 mature worms and 2 incomplete specimens. Entire worms 1.5–2.75 mm (1.85 ± 0.38; 11;11) long, greatest width at level of mature proglottids ( Fig. 3 ), euapolytic; 6–9 (7 ± 2; 11; 11) proglottids per worm ( Fig. 3 ). Scolex consisting of scolex proper and cephalic peduncle, scolex proper with four bothridia, 210–300 (267 ± 24; 11; 11) long, 175–200 (189 ± 11; 11; 11) wide. Maximum width of scolex at level of posterior margin of anterior loculus ( Figs. 22 and 27 ); surfaces of scolex covered with microtriches ( Fig. 28 ). Bothridia free posteriorly, 193–250 (214 ± 13; 11; 21) long by 75–113 (88 ± 8; 11; 21) wide; each with 3 loculi separated by two transverse septa, and specialized anterior region in form of muscular pad ( Figs. 22 and 27 ). Muscular pad 54–60 (58 ± 3; 11; 23) long by 75–100 (90 ± 7; 11; 23) wide, with apical sucker 22–24 (23 ± 1; 11; 22) long by 38–43 (40 ± 2; 11; 22), each with one pair of bipronged hooks at posterior margin ( Figs. 22 and 27 ). Anterior loculus of bothridia 113–163 (134 ± 12; 10; 20) long; middle loculus 30–50 (41 ± 5; 10; 20) long; posterior loculus 30–50 (38 ± 5; 10; 20) long ( Figs. 22 and 27 ); loculus length ratio (anterior:middle:posterior) 1:0.31:0.28. Velum absent ( Fig. 22 ).

Hooks bipronged, hollow, with tubercle on proximal surface of axial prong; internal channels of axial and abaxial prongs continuous, smooth, and base and anterior part of each hook embedded in muscular pad, axial and abaxial hooks approximately equal in size ( Figs. 22–23 and 27 ). Bases (handles) of medial and lateral hooks articulated each another ( Fig. 23 ). Lateral hook measurements: A 38–45 (40 ± 3; 11; 21), B 65–98 (78 ± 7; 11; 21), C 70–93 (79 ± 6; 11; 21), D 95–133 (110 ± 9; 11; 21). Medial hook measurements: A’ 33–43 (37 ± 3; 11; 23), B’ 68–100 (82 ± 9; 11; 27), C’ 68–100 (79 ±7; 11; 23), D’ 100–140 (115 ± 10; 11; 27).

Cephalic peduncle 260–640 (357 ± 104; 13; 13) long by 60–95 (77 ± 12; 13; 13) wide, covered with microtriches ( Fig. 29 ). Proglottids craspedote. Immature proglottids 2–6 (4 ± 1; 11; 11) in number, 50–195 (96 ± 34; 10; 17) long by 113–175 (134 ± 20; 10; 17) wide; mature proglottids 3–4 (3 ± 0.5; 11; 11) in number, 215–400 (286 ± 74; 5; 6) long by 123–153 (141 ± 11; 5; 6) wide ( Figs. 3 and 24 ), terminal mature proglottids 500–710 (577 ± 63; 11; 10) long by 170–240 (197 ± 24; 11; 10) wide ( Figs. 3 and 25 ). Gravid proglottids not observed. Genital pores marginal, irregularly alternating, 50–56% (52 ± 3%; 11; 5) of proglottid length from anterior end in mature proglottids. Testes oval in frontal view, arranged in two regular columns anterior to ovarian isthmus, 13–33 (21 ± 5; 11; 31) long by 25–55 (36 ± 9; 11; 31) wide ( Figs. 3 , 24–25 ); testes 21–32 (27 ± 3; 11; 17) in total number, 10–17 (14 ± 2; 11; 17) aporal, 8–11 (10 ± 1; 11; 17) preporal, 3–4 (4 ± 1; 11; 17) postporal, no testes posterior to ovarian isthmus. Cirrus sac pyriform, extending medially ( Figs. 24–26 , 30 ), 50–110 (73 ± 17; 10; 10) long by 18–38 (26 ± 8; 10; 10) wide in mature proglottids. Cirrus armed with spinitriches. Vagina narrow and relatively thick walled covered with gland cells, reaching to anterior of cirrus sac to common genital atrium; vaginal sphincter absent; seminal receptacle not seen. Ovary asymmetrical; poral lobe 70–145 (100 ± 26; 9; 9) long in mature proglottids, reaching to cirrus sac; aporal lobe 95–188 (131 ± 36; 9; 9) long, reaching to anterior margin of cirrus sac ( Figs. 24, 25 ), inverted A-shaped in frontal view ( Figs. 24 and 25 ), lobulated, ovarian isthmus posterior to mid-point of ovary. Mehlis’ gland posterior to ovarian isthmus. Vitellarium follicular, follicles arranged in two lateral bands; each band consisting of oval follicles; extending from near anterior margin of proglottid to near posterior margin of proglottid, interrupted by vagina and cirrus sac ( Fig. 25 ); follicles 8–13 (10 ± 2; 10; 22) long by 13–20 (15 ± 2; 10; 22) wide. Uterus thin-walled, sacciform, extends from near anterior margin of proglottid to near to near oӧ type. Excretory ducts lateral. Eggs not seen.

Remarks: Acanthobothrium sinaloaensis n. sp. is a Category 2 species (sensus Ghoshroy & Caira 2001): Species have a total length ≤ 15 mm (1.5–2.75 mm); number of proglottids ≤ 50 proglottids (6–9 proglottids); the number of testes per proglottids ≤ 80 (21–32 testes per proglottid); and with an asymmetrical ovary. The new spe- cies is the eighth species of Acanthobothrium reported from H. longus in the world being preceded by A. cimari ; A. hypanus n. sp.; A. puntarenasense and A. vargasi that have been reported as Category 2 species (see Table 1 ); A. cleofanus that has been reported as Category 3 species, and A. obuncus that has been reported as Category 6 species. There are currently 43 described Category 2 species (including A. hypanus n. sp. and A. ppdeleoni n. sp.). Acanthobothrium sinaloaensis n. sp. differs from all but A. campbelli ; A. dasi ; A. olseni ; A. vargasi , and two of them described above. The new species can be distinguished from A. campbelli , A. dasi , A. hypanus n. sp., and A. vargasi by the width of the scolex proper (175–200 vs. 211–255, 213–288, 300–350 and 378 n=1, respectively). The width of the accessory sucker of the new species is shorter than that of A. hypanus n. sp. (38–43 vs. 43–55) and greater than that of A. olseni and A. ppdeleoni n. sp. (38–43 vs. 24–34 and 25–38). The length of the bothridia of the new species is shorter than that of A. dasi and A. vargasi (193–250 vs. 293–410, 293–362); the width of the bothridia of the new species is shorter than that of A. hypanus n. sp., A. olseni and A. vargasi (80–105 vs. 113–150, 120–168 and 121–145, respectively). The width of the cirrus sacs in mature proglottids of the new species is shorter than that of A. dasi and A. olseni (18–38 vs. 43–90 and 84–168). The total number of testes per mature proglottid in A. sinaloaensis n. sp. is less than that of A. hypanus n. sp. (21–32 vs. 36–47). The number of aporal testes in mature proglottids of the new species is less than those of A. dasi and A. hypanus n. sp. (10–17 vs. 22–37 and 19–24). The length of the poral lobe of the ovary in the mature proglottids of the new species is shorter than that of A. dasi , A. hypanus n. sp., A. ppdeleoni n. sp. and A. vargasi (70–145 vs. 178–335, 150–285, 220–350 and 158–381, respectively). The number of immature proglottids in the A. sinaloaensis n. sp. is less than that of A. hypanus n. sp. (2–6 vs. 11–16). Finally, A. sinaloaensis n. sp. does no present velum between of bothridia and A. ppdeleoni n. sp. and A. hypanus n. sp. has velum between medial margins of bothridia.

Figures

FIGURES 1–3. Light microscope photographs of entire worms of the three new species (Holotypes). 1. Acanthobothrium ppdeleoni n. sp. (CNHE–11253); 2. Acanthobothrium hypanus n. sp. (CNHE–11255); 3. Acanthobothrium sinaloaensis n. sp. (CNHE–11257). Scale bars: 1, 2 and 3 = 500 μm.

FIGURES 22–26. Holotype of Acanthobothrium sinaloaensis n. sp. (CNHE–11257): 22. Scolex; 23. Hooks; 24. Mature proglottid; 25. Terminal mature proglottid; 26. Genitalia. Scale bars: 22 = 100 μm; 23, 24, 25 and 26 = 50 μm.

FIGURES 27–30. Light microscope photographs of holotype of Acanthobothrium sinaloaensis n. sp. (CNHE–11257): 27. Scolex; 28. Details of bothridium; 29. Details of peduncle cephalic; 30. Genitalia. Scale bars: 27 = 50 μm; 28, 29 and 30 = 10 μm. Abbreviations: mt, microtriches; vg, vagina; cs, cirrus sac; gp, genital pore.