Acanthobothrium ppdeleoni, 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 : 158-161

Acanthobothrium ppdeleoni n. sp.

( Figs. 1 , 4–12 )

urn:lsid:zoobank.org:act:F5611609-1B2D-42D9-9B1C-A2328EDD6DAB

Type host: Hypanus dipterurus ( Myliobatiformes : Dasyatidae ).

Type locality: Bahía de Chamela, Jalisco, Mexico.

Site of infection: Spiral intestine.

Deposited material: Holotype ( CNHE–11253 ), 5 paratypes (CNHE–11254), and 7 paratypes (HWML– 216260).

ZooBank registration: The Life Science Identifier (LSID) urn:lsid:zoobank.org:act:F5611609-1B2D-42D9-9B1C-A2328EDD6DAB

Etymology: This species is named in honor of Dr. Gerardo Pérez-Ponce de León of the Laboratorio de Helmintología, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, México, for his contributions to knowledge of Platyhelminthes.

Description. Based on whole mounts of 9 mature worms and 5 incomplete specimens. Entire worms 2.5–5.95 mm (3.76 ± 1.2; 9; 9) long, greatest width at scolex ( Fig. 1 ), euapolytic; 6–14 (11 ± 3; 9; 9) proglottids per worm ( Fig. 1 ). Scolex consisting of scolex proper and cephalic peduncle, scolex proper with four bothridia, 225–365 (285 ± 44; 11; 11) long by 160–250 (219 ± 27; 10; 10) wide. Maximum width of scolex at level of middle loculus ( Figs. 4 and 9 ); surfaces of scolex covered with microtriches ( Fig. 10 ). Bothridia free posteriorly, 188–263 (224 ± 19; 11; 20) long by 78–125 (104 ± 13; 11; 20) wide; each with 3 loculi separated by two transverse septa, and specialized anterior region in form of muscular pad ( Figs. 4 and 9 ). Muscular pad 60–70 (66 ± 3; 11; 14) long by 83–100 (91 ± 6; 11; 14) wide, with apical sucker 24–31 (27 ± 3; 11; 22) long by 25–38 (31 ± 4; 11; 22) wide, each with one pair of bipronged hooks at posterior margin ( Figs. 4 and 9 ). Anterior loculus of bothridia 125–150 (131 ± 8; 10; 20) long; middle loculus 35–63 (42 ± 7; 10; 20) long; posterior loculus 25–75 (53 ± 13; 10; 20) long ( Figs. 4 and 9 ); loculus length ratio (anterior:middle:posterior) 1:0.32:0.40. Velum present between medial margins of bothridia at posterior margin of middle loculus ( Figs. 4 and 9 ).

Hooks bipronged, hollow, with tubercle on proximal surface of axial prong; internal channels of axial and abaxial prongs continuous, smooth, the base and anterior part of each hook embedded in muscular pad, axial prongs slightly longer than abaxial prongs ( Figs. 4–5 and 9 ). Bases (handles) of medial and lateral hooks articulated each another; lateral and medial hooks approximately equal size ( Figs. 5 and 9 ). Lateral hook measurements: A 38–50 (42 ± 4; 11; 21), B 80–113 (88 ± 9; 11; 20), C 75–113 (85 ± 10; 11; 17), D 113–158 (127 ± 11; 11; 20). Medial hook measurements:A’ 38–48 (40 ± 3; 11; 22), B’ 85–125 (95 ± 11; 11; 22), C’ 75–115 (87 ± 11; 11; 21), D’ 113–160 (129 ± 11; 11; 22).

Cephalic peduncle 300–925 (645 ± 181; 13; 13) long by 60–125 (81 ± 18; 13; 13) wide, covered with microtriches ( Fig. 11 ). Proglottids acraspedote. Immature proglottids 4–9 (6 ± 2; 9; 9) in number, 65–170 (103 ± 29; 13; 13) long by 100–168 (131 ± 22; 13; 13) wide; mature proglottids 3–5 (4 ± 1; 9; 9) in number, 338–1,025 (544 ± 191; 13; 13) long by 140–210 (179 ± 22; 13; 13) wide ( Figs. 1 and 6 ), terminal mature proglottids 650–1,055 (920 ± 183; 4; 4) long by 135–210 (183 ± 33; 4; 4) wide ( Figs. 1 and 7 ). Gravid proglottids not observed. Genital pore marginal, irregularly alternating, 46–64% (56± 5; 13; 13) of proglottid length from anterior end. Testes arranged in two irregular columns, one column on each side of the uterus anterior to ovarian isthmus ( Fig. 6 ), 28–38 (34 ± 3; 9; 18) long by 33–53 (41 ± 6; 9; 18) wide ( Fig. 6 ); testes 20–44 (33 ± 7; 9; 14) in total number, 11–25 (18 ± 4; 9; 14) aporal, 6–16 (11 ± 3; 9; 14) preporal, 3–5 (4 ± 1; 9; 14) postporal, no testes posterior to ovarian isthmus. Cirrus sac pyriform, extending anteriorly ( Figs. 6–8 and 12 ), 113–148 (131 ± 18; 7; 7) long by 63–88 (75 ± 13; 7; 7) wide in mature proglottids, 113–148 (131 ± 18; 3; 3) long by 63–88 (75 ± 13; 3; 3) wide in terminal proglottids. Cirrus armed with spinitriches. Vagina relatively thick walled covered with gland cells, extending along medial line of proglottid from oӧ type, reaching to anterior of cirrus sac to common genital atrium; vaginal sphincter absent; semi- nal receptacle not seen. Ovary occupying posterior of proglottid, asymmetrical; poral lobe 220–350 (282 ± 45; 7; 7) long in mature proglottids, reaching cirrus sac; aporal lobe 213–438 (329 ± 79; 7; 7) long in mature proglottids, reaching anterior margin of cirrus sac ( Figs. 6 and 7 ), inverted A-shaped in frontal view ( Figs. 1 , 6–7 ), lobulated, ovarian isthmus posterior to mid-point of ovary; Mehlis’ gland posterior to ovarian isthmus. Vitellarium follicular, in two columns, on each lateral side of proglottid, extending from near anterior margin of proglottid, to near posterior margin of proglottid, interrupted by vagina and cirrus sac ( Figs. 6 and 7 ); follicles 13–15 (13 ± 1; 9; 15) long by 13–30 (20 ± 7; 9; 15). Uterus thin-walled, sacciform, occupying midline of proglottid, extends from ovarian isthmus to near anterior margin of proglottid. Excretory ducts lateral. Eggs not seen.

Remarks: Acanthobothrium ppdeleoni n. sp. is a Category 2 species (sensus Ghoshroy & Caira 2001): Species have a total length ≤ 15 mm (2.5–5.95 mm); number of proglottids ≤ 50 proglottids (6–14 proglottids); the number of testes per proglottids ≤ 80 (20–44 testes per proglottid); and with an asymmetrical ovary. The new species is the fifth species of Acanthobothrium reported from H. dipterurus being preceded by A. bullardi ; A. dasi and A. rajivi that have been reported as Category 2 species and A. soberoni Ghoshroy & Caira, 2001 that has been reported as Category 6 species. There are currently 41 described Category 2 species ( Table 1 ). Acanthobothrium ppdeleoni n. sp. differs from all but A. campbelli ; A. coquimbensis ; A. dasi ; A. olseni and A. vargasi . The botridia of the new species is shorter than that of A. coquimbensis (188–263 x 78–125 vs. 312–480 x 136–200), the length of the cirrus sacs in mature proglottids of the new species is shorter than that of A. coquimbensis (80–125 vs. 200–400) and, the width of the testes in mature proglottids is grater than that of A. coquimbensis (33–53 vs. 12–24). The new species can be distinguished from A. campbelli by the total length of the whole worms that is longer than A. campbelli (2.5–5.95 vs. 0.99–1.80 mm), and A. campbelli has bases (handles) of the medial hooks shorter than those of A. ppdeleoni n. sp. (14–33 vs. 38–48). The new species differs from A. dasi by the length of the scolex proper (225–365 vs. 525–1,075), the length of bothridia is shorter than that of A. dasi (188–263 vs. 293–410) and A. ppdeleoni n. sp. has abaxial prong lengths slightly longer than those of A. dasi (75–113 vs. 50–75). The width of the cirrus sacs in mature proglottids of the new species is shorter than that of A. olseni (38–75 vs. 84–168), and the length of the testes of A. ppdeleoni n. sp. is shorter than that of A. olseni (28–38 vs. 43–72). The new species differs from A. vargasi in the width of the scolex proper (160–250 vs. 378 n=1), and the length of the bothridia (188–263 vs. 293–362).

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 4–8. Holotype of Acanthobothrium ppdeleoni n. sp. (CNHE–11253): 4. Scolex. Note: the black arrow tip show the presence of velum; 5. Hooks; 6. Mature proglottid; 7. Terminal mature proglottid; 8. Genitalia. Scale bars: 4, 6, 7 and 8 = 100 μm; 5. = 50 μm.

FIGURES 9–12. Light microscope photographs of holotype of Acanthobothrium ppdeleoni n. sp. (CNHE–11253): 9. Scolex; 10. Details of bothridium; 11. Details of peduncle cephalic; 12. Genitalia. Scale bars: 9 = 100 μm; 10 and 11 = 10 μm; 12 = 50 μm. Abbreviations: vl, velum; mt, microtriches; vg, vagina; cs,cirrus sac; gp, genital pore.