Caulobothrium katzi, Caira & Jensen, 2021

Caira, Janine N. & Jensen, Kirsten, 2021, Two new species of Caulobothrium (Cestoda: “ Tetraphyllidea ”) from the duckbill eagle ray, Aetomylaeus bovinus (Myliobatiformes: Myliobatidae), off Senegal with new insights on morphological features of the genus, Zootaxa 4903 (1), pp. 127-139 : 132-136

Caulobothrium katzi n. sp.

( Figs. 3 , 4 , 5C, D )

Zoobank No. 252FA59A-B537-40F8-A91E-7F7B1CBBCFAA

Type host: Aetomylaeus bovinus (Geoffroy St. Hilaire) , duckbill eagle ray ( Myliobatiformes : Myliobatidae ).

Type locality: St. Louis (16°1’28”N, 16°30’33”W), Senegal, Atlantic Ocean .

Additional locality: Diogue (12°34’30”N, 16°45’2”W), Casamance , Senegal, Atlantic Ocean .

Site of infection: Spiral intestine.

Prevalence of infection: 100% (2 of 2 duckbill eagle rays examined).

Type specimens: MNHN No. HEL1369 (holotype); LRP No. 10305 (1 paratype), LRP Nos. 10243–10251 (cross sections of strobila of 1 paratype stained with H&E); LRP Nos. 10252–10253 (cross sections of strobila of 1 paratype stained with H&E) ; USNM Nos. 1638631–1638633 (3 paratypes; 2 with scolices SEM specimens retained in the personal collection of the senior author.

Etymology: This species is named in honor of Theodore Katz whose undergraduate thesis on the diversity of Caulobothrium laid the foundation for our current understanding of the morphology of this genus overall.

Description. Based on whole mounts of 2 complete and 4 partial worms (including Healy et al. ’s [2009] molecular voucher of Caulobothrium n. sp. 3 [LRP No. 3915]), cross sections of 2 partial strobila, and 2 scolices examined with SEM.

Worms anapolytic, 9.4–12.6 cm long; greatest width 1,301 –1,795 at level of mature or gravid proglottids; 430– 515 proglottids per worm. Scolex consisting of 4 stalked bothridia and cephalic peduncle ( Figs. 3A , 4A ). Bothridia 1,092 –1,765 (1370 ± 180; 4; 12) long, 289–405 wide, bearing single anterior loculus with apical sucker and 2 columns of 17 loculi each and single posterior loculus; loculi 36 in total number; apical sucker inconspicuous ( Fig. 4B ), 10–22 long, 10–23 wide. Cephalic peduncle extensive, 12–16 (14 ± 1.5; 5) mm long, 658–828 (746 ± 68; 5) wide.

Distal surface of bothridial loculi and septa with acicular filitriches ( Fig. 4E ); distal surface of apical sucker with blend of acicular and papilliform filitriches ( Fig. 4B ); distal surface of bothridial rims with band of papilliform filitriches ( Fig. 4D ). Proximal surface of bothridium with acicular filitriches only ( Fig. 4F ). Spinitriches not observed on any bothridial surfaces. Cephalic peduncle surface with densely arranged small gladiate spinitriches; filitriches not observed ( Fig. 4G ).

Proglottids craspedote, anterior margin wider than posterior margin of preceding proglottid in some. Immature proglottids 354–364 in number, wider than long. Mature proglottids 49–88 in number, wider than long; 2 posterior-most mature proglottids 349–573 (498 ± 84; 4; 8) long, 1,042 –1,388 (1,247 ± 126; 4; 8) wide, width to length ratio 1.9–4:1 (2.6 ± 0.7; 4, 8). Gravid proglottids 12–24 in number, wider than long. Post-gravid proglottids 15–39 in number, wider than long, becoming longer than wide towards posterior of strobila. Genital pores lateral, irregularly alternating, 47–55% of proglottid length from posterior margin of proglottid in 2 posterior-most mature proglottids. Testes 69–89 (79 ± 6; 6; 12) in total number, 16–53 long, 35– 69 wide, extending from anterior of proglottid to ovarian bridge ( Fig. 5D ); 2 irregular layers deep in cross section ( Fig. 5C ); post-poral testes present, 10–23 (17 ± 4; 6; 12) in number; post-ovarian testes absent. Vas deferens extensively coiled in center of proglottid, joining cirrus sac at antero-medial margin. Cirrus sac bent slightly anteriorly, highly elongate, narrow, 342–568 (466 ± 111; 5; 5) long, 33–75 (52 ± 16; 5; 5) wide in posterior-most 2 mature proglottids, not reaching midline of proglottid, containing coiled cirrus; cirrus unarmed. Ovary 133–183 (163 ± 18; 4; 8) long, 630–1,140 (821 ± 209; 4; 8) wide in 2 posterior-most mature proglottids, weakly H-shaped in dorso-ventral view, tetralobed in cross section ( Fig. 5D ); ovarian margins lobulated. Vagina essentially straight, extending from ootype along midline of proglottid, passing ventral to cirrus sac, opening into genital atrium slightly anterior to cirrus; vaginal sphincter not observed. Vitellarium follicular; vitelline follicles wider than long, 6–23 (13 ± 4; 5; 30) long, highly variable in width, in relatively extensive lateral fields of multiple follicles; lateral fields extending from near anterior margin of proglottid to near posterior margin of proglottid, uninterrupted by terminal genitalia and ovary. Uterus medial, ventral, extending to anterior margin of proglottid, sacciform in mature proglottids, developing lateral diverticula in gravid proglottids; posterior diverticula extending posterio-lateral to and compressing ovary into triangular form when filled with eggs. Excretory vessels 4, arranged in 1 dorsal and 1 ventral pair on each lateral margin of proglottid. Details of eggs not observed.

Remarks. Caulobothrium katzi n. sp. is one of the largest, most robust members of the genus; it is greater in TL than its small-bodied congeners C. pedunculatum , C. multispelaeum , C. myliobatidis , C. ostrowskiae , C. opisthorchis , C. longicolle , and C. uruguayense (9.4–12.6 cm vs. 1.0–5.4, 1.7–3.4, 2.5–6, up to 15, less than 15, 28, and up to 30 mm, respectively). It also has a greater number of proglottids than C. myliobatidis , C. pedunculatum , C. multispelaeum , C. ostrowskiae , C. opisthorchis , and C. uruguayense (i.e., 430–515 vs. 7–16, 8–15, 8–18, 16–20, about 25, and 100–150, respectively). It differs from C. tetrascaphium and C. tobijei , which are the other two large species in the genus, in having conspicuously fewer testes (69–89 vs. more than 200 and 140–160, respectively). It further differs from both species in the number and/or arrangement of facial loculi. Whereas C. katzi n. sp. bears a total of 36 loculi (1 anterior and 1 posterior loculus, and 2 columns of 17 loculi each), C. tetrascaphium bears a total of 22 loculi arranged in two columns of 11 each, and C. tobijei bears only a single column of 16 loculi.

This species was assigned the provisional name Caulobothrium n. sp. 3 by Healy et al. (2009), with the associated GenBank record No. FJ177103 . We are hereby formally establishing this taxon as Caulobothrium katzi n. sp.

Figures

FIGURE 3. Line drawings of Caulobothrium katzi n. sp. from Aetomylaeus bovinus off Senegal. A. Scolex (holotype; MNHN No. HEL1369). B. Whole worm (holotype; MNHN No. HEL1369). C. Detail of terminal genitalia (holotype; MNHN No. HEL1369). D. Mature proglottid (paratype; USNM No. 1638631).

FIGURE 4. Scanning electron micrographs of Caulobothrium katzi n. sp. from Aetomylaeus bovinus off Senegal. A. Scolex; small letters indicate locations of details in E–G. B. Anterior region of bothridium showing inconspicuous apical sucker (arrow). C. Proximal surface of bothridial rim at level of loculi. D. Distal surface of bothridial rim. E. Distal surface of bothridium away from rim. F. Proximal surface of bothridium. G. Surface of cephalic peduncle.

FIGURE 5. Light micrographs of sections of Caulobothrium multispelaeum n. sp. and Caulobothrium katzi n. sp. stained with Delafield’s hematoxylin and counter-stained with eosin. A. Cross section of mature proglottid of C. multispelaeum n. sp. anterior to cirrus sac. B. Cross section of mature proglottid of C. multispelaeum n. sp. at level of ovarian isthmus. C. Cross section of mature proglottid of C. katzi n. sp. anterior to cirrus sac. D. Cross section of mature proglottid of C. katzi n. sp. slightly posterior to ovarian isthmus. Abbreviations: O, ovary; T, testis; VF, vitelline follicle.