Acanthobothrium persicum, 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 : 301-304

Acanthobothrium persicum n. sp.

( Figs. 43–52 )

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

Additional host: None.

Type locality: Persian Gulf (26° 15´N, 53° 02´E – 27° 04´N, 57° 01´E), Iran .

Additional localities: None.

Site of infection: Spiral intestine.

ZooBank registration: The Life Science Identifier (LSID)

urn:lsid:zoobank.org:act:AB6340D8-CDF5-47CD-B6DC-F1C2ABDB1457 .

Deposited material: Holotype ( ZCUOK. 135), 2 paratypes ( ZCUOK 136 – ZCUOK 137 ), 2 paratypes ( ZUTC Platy. 1351– ZUTC Platy. 1352), 1 SEM voucher ( ZCUOK 142 ), 1 SEM voucher ( ZUTC Platy. 1353).

Prevalence of infection: 3.3% (1 of 30 individuals examined).

Etymology: This species is named for its type locality, the Persian Gulf, a centre of shark cestode biodiversity.

Description: Based on whole mounts of 5 mature worms, 2 scolex examined with SEM, and 2 whole mounts of their voucher. Worms 2.76–6.25 mm (4.3±1.2; 5; 5) long, greatest width at terminal proglottid; 19–30 (24.5±4.2; 5; 5) proglottids per worm; worms euapolytic. Scolex consists of scolex proper and conspicuous cephalic peduncle. Scolex proper with 4 bothridia, 272–306 (283±15.4; 5; 4) long. Bothridia free posteriorly, 405–477 (431±32.6; 6; 4) long by 171–199 (188±12.3; 6; 4) wide; each with 3 loculi separated by two transverse septa, and specialized anterior region in form of muscular pad; muscular pad 65–129 (100±29.7; 5; 4) long by 83–130 (101±20.7; 6; 4) wide, oval in shape, consisting of apical sucker and 1 pair of hooks at posterior margin; accessory sucker 26–41 (34±6.7; 5; 4) long by 31–58 (45±11.5; 5; 4) wide; anterior loculus with two lappets at posterolateral margins, 93–220 (171±47; 5; 5) long; middle loculus 30–81 (66±20.7; 5; 5) long; posterior loculus 48–107 (89±23.3; 5; 5) long; ratio of locular length (anterior: middle: posterior) 1:0.32–0.41: 0.45–0.57; maximum width of scolex, 310–408 (364±40.4; 5; 4), at level posterior margin 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 43–56 (51±6.2; 5; 5), B 72–98 (88±11.3; 5; 5), C 49–71 (59±11.1; 5; 5), D 106–145 (129±16.7; 5; 5), E 90–133 (111±18.2; 5; 5), W 39–62 (47±10.2, 5; 5). Medial hook measurements: A´ 41–55 (49±5.1; 5; 6), B´ 78–93 (85±6.1; 5; 5), C´ 39–67 (48±11.5, 5; 5), D´ 111–140 (125±11.5, 5; 5), E´ 76–113 (93±13.9; 5; 5), W´ 36–56 (48±8.6; 5; 5). Bases of lateral and medial hooks equal in length; hook bases embedded in muscular pad, bases covered with a encrusted sclerotisation. Cephalic peduncle 88–165 (135±31; 5; 5) long by 117–232 (185±47; 5; 5) wide at mid-level.

Apical pad surface ( Figs. 48, 49 ), and distal bothridial surface ( Fig. 51 ) covered with papilliform filitriches. Proximal bothridial surfaces ( Fig. 50 ) covered with papilliform to slightly acicular filitriches. Cephalic peduncle surface ( Fig. 52 ) covered with densely arranged gladiate spinitriches.

Proglottids acraspedote, protandrous. Immature proglottids 13–24 (19±4.5; 5; 5) in number; mature proglottids 3–6 (4.5±1.3; 5; 5) in number. Terminal mature proglottid 537–843 (683±104; 7; 7) long by 186–449 (322±96; 7; 7) wide, length: width ratio 1.4–2.8 (2.1±0.4; 7; 7):1. Gravid proglottids not seen. Genital pores lateral, alternating irregularly, 8–20% (12±4; 7; 7) of proglottid length from posterior end. Testes irregularly round to oval in dorsoventral view, 37–53 (44±5.2; 7; 11) long by 37–101 (53±41; 7; 11) wide, arranged in 2 regular columns well anterior to ovary, 38–49 (43±3.8; 7; 10) in total number, no testes in post-vaginal field, no testes posterior to ovarian field. Cirrus sac narrow, oval in mature proglottid, extending anteriorly along poral arm of ovary, 90–252 (139±53; 7; 7) long and 33–95 (60±22; 7; 7) wide, containing coiled cirrus, cirrus expanded at base; most of cirrus length covered with spinitriches. Vas deferens in mid-part of mature proglottid. Vagina short, thick walled, extending from o ӧtype along midline of proglottid to near anterior margin of poral lobe of ovary, then posteriorly following anterior margin of cirrus sac to common genital atrium; vaginal sphincter absent; seminal receptacle not seen. Ovary located in posterior third part of proglottid, poral lobe slightly displaced by cirrus sac, symmetrical, 118–232 (173±38; 7; 7) long, maximum width of ovary 79–200 (145±47.6; 7; 7), 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 follicles, extending from anterior margin of testes to near anterior margin of ovary, interrupted by vagina and cirrus sac and ovary; Vitelline follicles irregular, 15–34 (21±6.3; 7; 12) long by 9–30 (19±6.4; 7; 12) wide. Uterus median, thin-walled, sacciform, extending from near anterior part of proglottid to near o ӧtype. Excretory ducts lateral. Eggs spherical, unembryo- nated in utero.

Remarks: Acanthobothrium persicum sp. n. is a Category 1 species according to the categorization system by Ghoshroy & Caira (2001) (<15 mm in total length, <50 proglottids, <80 testes, with symmetrical ovary). It differs from all 51 Category 1 species (including 4 species described above) but 5 species in the possession of position of the genital pore in the posterior one-fifth of the proglottid, the lack of post-vaginal testes and the orientation of cirrus sac approximately parallel to the ovarian lobes. However, A. persicum n. sp. can be distinguished from A. omanense n. sp. with having more proglottids per worm (19–30 vs. 10–18), a wider scolex (310–408 vs. 234–306) and a wider cephalic peduncle (128–230 vs. 57–107). The new species differs from A. kurdistanense n. sp. and A. makranense n. sp. with the possession of a longer cephalic peduncle (88–165 vs. 36–82 and 38–80, respectively) and more testes (38–45 vs. 28–37 and 27–34, respectively). Acanthobothrium persicum n. sp. can be distinguished from A. halehae n. sp. with longer hooks (111–140 vs. 86–109) and more testes per proglottid (38–45 vs. 30–37). It can be distinguished from the other four newly described species by the genital pore extending posterior to the ovarian lobes, close to the posterior end of the proglottids. Acanthobothrium persicum n. sp. also possesses two lappets on its bothridia unlike A. fogeli which lacks of lappets on the bothridia. The genital pore position in A. persicum n. sp. (8–20%) is close to the posterior end of the proglottids compared with the other Acanthobothrium species from the Persian Gulf and Gulf of Oman (see remarks above).

Figures

FIGURES 43–46. Acanthobothrium persicum n. sp. 43. Scolex.Arrow shows the marginal lappet. 44. Hooks. 45. Whole worm. 46. Terminal proglottid. Scale bars: Figs. 43, 44= 50 µm; Fig. 45=200 µm. Fig. 46=100 µm.

FIGURES 47–52. Scanning electron micrographs of Acanthobothrium persicum n. sp. 47. Scolex. Note: Small numbers on scolex correspond to the figures showing higher magnification images of these surfaces and white arrow tip show the marginal lappet. 48. Apical pad and hooks. 49. Surface of apical pad. 50. Proximal bothridial surface. 51. Distal bothridial surface. 52. Cephalic peduncle surface. Scale bars: Fig. 47=100 µm; Fig. 48=40 µm; Fig. 52=3 µm; Figs. 50=2 µm; Figs. 49, 51=1 µm.