Acanthobothrium omanense, Maleki & Malek & Palm, 2019

Maleki, Loghman, Malek, Masoumeh & Palm, Harry W., 2019, Five new species of Acanthobothrium (Cestoda: Onchoproteocephalidea) from the long-tailed butterfly ray, Gymnura cf. poecilura (Elasmobranchii: Gymnuridae) from the Persian Gulf and Gulf of Oman, Zootaxa 4609 (2), pp. 289-307 : 290-291

Acanthobothrium omanense n. sp.

( Figs. 1–5 , 10–15 )

Type host: Gymnura cf. poecilura , Long-tailed butterfly ray ( Myliobatiformes : Gymnuridae ).

Type locality: Gulf of Oman (25° 11´N, 60° 33´E– 25° 25´N, 57° 43´E) , Iran.

Additional localities: Persian Gulf

Site of infection: Spiral intestine.

ZooBank registration: The Life Science Identifier (LSID) urn:lsid:zoobank.org:act:741B8217-BB7B-454C-AF35-DDAC48E3E694 .

Deposited material: Holotype ( ZCUOK. 117), 5 Paratypes ( ZCUOK 118 – ZCUOK 122 ), 5 paratypes ( ZUTC Platy. 1330– ZUTC Platy. 1334), 1 SEM voucher ( ZUTC Platy. 1335).

Prevalence of infection: 13.3% (4 of 30 individuals examined).

Etymology: This new species is named after its type locality, the Gulf of Oman.

Description: Based on whole mounts of 11 mature worms, 1 scolex examined with SEM, and a whole mount of its voucher. Worms 2.6–5.2 mm (3.6±0.8; 11; 11) long, greatest width at scolex; 10–18 (13±2; 11; 11) proglottids per worm; euapolytic. Scolex consists of scolex proper and conspicuous cephalic peduncle. Scolex proper with 4 bothridia, 199–278 (246±27; 11; 10) long. Bothridia free posteriorly, 145–382 (321±65; 11; 10) long by 112–371 (154±77; 11; 10) wide; each with 3 loculi separated by two transverse septa, and specialized anterior region in form of muscular pad; muscular pad 85–108 (92±7.8; 11; 11) long by 76–114 (92±7.8; 11; 11) wide, rounded in shape, consisting of apical sucker and 1 pair of hooks at posterior margin; accessory sucker 30–52 (40±7.4; 11; 10) long by 39–61 (50±6.9; 11; 10) wide; anterior loculus with two lappets at posterolateral margins, 128–185 (156±19; 11; 10) long; middle loculus 39–48 (43±3.5; 11; 10) long; posterior loculus 49–87 (65±13.6; 11; 10) long; ratio of locular lengths (anterior: middle: posterior) 1: 0.24–0.37: 0.31–0.47; maximum width of scolex, 234–306 (262±21; 11; 9), at level of anterior loculus. Velum between pair of adjacent bothridia present.

Hooks bipronged, hollow, with tubercle on proximal surface of axial prong; internal channels of axial and abaxial prongs continuous, lateral and medial hooks equal in size; axial prongs slightly longer than abaxial prongs. Lateral hook measurements: A 37–48 (41±3.3; 11; 12), B 69–87 (78±6.6; 11; 12), C 46–64 (54±5; 11; 12), D 102–124 (113±7.6; 11; 12), E 82–108 (95±7.4; 11; 12), W 36–51 (43±4.5, 11; 12). Medial hook measurements: A´ 35–48 (41±3.7; 11; 12), B´ 71–86 (77±4.5; 11; 12), C´ 44–59 (52±3.7, 11; 12), D´ 104–125 (113±6.9, 11; 12), E´ 80–107 (93±6.8; 11; 12), W´ 39–45 (40±2; 11; 12). Bases of lateral and medial hooks approximately equal in length; hook bases embedded in muscular pad, bases covered with encrusted sclerotisation. Cephalic peduncle 125–315 (187±56.8; 11; 10) long by 57–107 (89±16; 11; 10) wide at mid-level.

Apical pad surface ( Figs. 11, 12 ), proximal bothridial surfaces ( Fig. 13 ) and distal bothridial surface ( Fig. 14 ) covered with papilliform filitriches. Cephalic peduncle surface ( Fig. 15 ) covered with densely arranged blade-like gladiate spinitriches interspersed with capilliform filitriches.

Proglottids acraspedote, protandrous. Immature proglottids 10–12 (10.6±0.8; 12; 9) in number; mature proglottids 1–3 (2.1±0.6; 12; 9) in number. Terminal mature proglottid 425–998 (668±150; 12; 12) long by 128–276 (199±41; 12; 12) wide, length: width ratio 2.2–5.3 (3.4±.9; 12; 12): 1. Gravid proglottids not observed. Genital pores lateral, alternating irregularly, 11–19 % (15.3±2.7; 12; 11) of proglottid length from posterior end. Testes irregularly oval in dorsoventral view, 24–49 (40±6.5; 12; 17) long by 27–45 (36±4.6; 12; 17) wide, arranged in 2 regular columns anterior to ovary, 25–45 (33±4.8; 12; 12) in total number, no testes post-vaginal, no testes posterior to ovarian field. Cirrus-sac oval in mature proglottid, extending anteriorly along poral arm of ovary, 106–160 (134±16.9; 12; 12) long and 29–68 (50±11; 12; 12) wide, containing coiled cirrus; cirrus expanded at base; most of cirrus length covered with spinitriches. Massive vas deferens in mid-part of mature proglottid. Vagina short, thick walled, sinuous, extending from o ӧtype along midline of proglottid to near anterior margin of poral lobe of ovary, then bent posteriorly along anterior margin of cirrus sac to common genital atrium; vaginal sphincter absent; seminal receptacle not seen. Ovary located in posterior third of proglottid, poral lobe distorted by cirrus sac, symmetrical, 138–258 (198±39; 12; 12) long, maximum width of ovary 58–163 (102±28; 12; 12), H-shaped in dorsoventral view, lobulated; reaching to posterior margin of testes; ovarian isthmus near mid-point of ovary; Mehlis’ gland posterior to ovarian isthmus. Vitellarium follicular, consisting of two lateral bands; each band consists of 2 columns of relatively large follicles, extending from near anterior extent of testes to near anterior margin of ovary, interrupted by vagina, cirrus sac and ovary; vitelline follicles irregular, 13–37 (23±6.9; 12; 15) long by 11–30 (17±5.1; 12; 15) wide. Uterus median, thin-walled, sacciform, extending from near anterior part of proglottid to near o ӧtype. Excretory ducts lateral. Eggs spherical.

Remarks: Acanthobothrium omanense n. sp. is a Category 1 species, according to the categories for Acanthobothrium species determined by Ghoshroy & Caira (2001) i.e. less than 15 mm in total length, fewer than 50 proglottids, fewer than 80 testes, and an ovary with symmetrical lobes. There are currently 48 described Category 1 species. Acanthobothrium omanense n. sp. differs from all but Acanthobothrium fogeli Goldstein, 1964 in the position of the genital pore in the posterior one-fifth of the proglottids, the orientation of the cirrus sac parallel to the ovarian lobes and having lappets on the bothridia. The new species can be distinguished from A. fogeli in having smaller accessory suckers (30–52 vs. 60–108) and the possession of distinct marginal lappets on its bothridia. This new species has more posterior genital pores (11–19%) than previously reported all other Acanthobothrium species in the Persian Gulf and Gulf of Oman, i.e. A. asrinae Maleki, Malek, Palm, 2015 (55–58%), A. fylerae Maleki, Malek, Palm, 2015 (57–72%), A. sphaera Maleki, Malek, Palm, 2013 (59–72%), A. janineae Maleki, Malek, Palm, 2015 (63–79%), A. jamesi Maleki, Malek and Palm, 2015 (71–74%) and A. jalalii Maleki, Malek and Palm, 2013 (72–80%).

Figures

FIGURES 1–5. Acanthobothrium omanense n. sp. 1. Scolex. Arrows show the marginal lappets. 2. Hooks. 3. Terminal mature proglottid. 4. Whole worm. 5. Terminal genitalia. Scale bars: Figs. 1, 2, 3, 5= 50 µm; Fig. 4= 100 µm.

FIGURES 10–21. FIGURES 10–15. Scanning electron micrographs of Acanthobothrium omanense n. sp. 10. Scolex. Note: Small numbers on the scolex correspond to the figures showing higher magnification images of these surfaces, and white arrow tip show the marginal lappet. 11. Apical pad and hooks. 12. Surface of apical pad. 13. Proximal bothridial surface. 14. Distal bothridial surface. 15. Cephalic peduncle surface. FIGURES 16–21. Scanning electron micrographs of Acanthobothrium kurdistanense n. sp. 16. Scolex. 17. Apical pad and hooks. 18. Surface of apical pad. 19. Proximal bothridial surface. 20. Surface of anterior region of strobila. 21. Distal bothridial surface. Scale bars: Fig 16=100; Fig. 10=80 µm; Figs. 11, 17=40 µm; Figs 15, 20=2 μm; Figs. 12, 13, 14, 18, 19, 21=1 µm.