Caulobothrium pieroi, Menoret & Ivanov, 2023

Menoret, Adriana & Ivanov, Verónica A., 2023, Cestodes of Pseudobatos horkelii (Müller and Henle) (Rhinopristiformes) including Rhinebothrium quequense n. sp. (Rhinebothriidea) and Caulobothrium pieroi n. sp. (“ Tetraphyllidea ”) from the southwestern Atlantic, Zootaxa 5361 (1), pp. 87-102 : 93-94

Caulobothrium pieroi n. sp.

urn:lsid:zoobank.org:act:B074FCF2-6E2E-4943-A86D-79D38AA01729

( Figs. 4–6 )

Type host: Pseudobatos horkelii (Müller and Henle) , Brazilian guitarfish ( Rhinopristiformes: Rhinobatidae ).

Type locality: Puerto Quequén (38°37’S; 58°53’W), Buenos Aires Province, Argentina, southwestern Atlantic .

Site of infection: Spiral intestine of P. horkelii .

Prevalence of infection: 50% (2 hosts infected out of 4 Brazilian guitarfishes examined).

Material deposited: Holotype (mature worm) MACN-Pa No. 779, 7 paratypes (2 mature worms, 5 strobilae without scolex) MACN-Pa No. 780/1–7.

Additional specimens (histological sections and specimens prepared for SEM) retained in the personal collection of Adriana Menoret.

Etymology: This species is named in memory of Piero Nardi Pantoli.

Description: Based on 8 whole mounts including 3 mature worms (2 complete worms and 1 worm with a bothridium), and 5 strobilae (4 with mature proglottids and 1 with terminal gravid proglottid); and histological sections of 1 terminal mature proglottid.

Clade 4: Worms apolytic, 4.7–6.1 (5.3 ± 0.6, n = 3) mm long; greatest width at the level of scolex; proglottids acraspedote, 8–22 (14 ± 5, n = 7) per worm ( Fig. 4A ). Scolex 755–825 (n = 2) long, 660–675 (n = 2) wide, composed of 4 stalked bothridia, facially loculate bothridia ( Fig. 4A, B ). Bothridia canoe-shaped, 680–850 (758 ± 63, n = 3) long, 170–280 (225 ± 16, n = 3) wide, with muscular rims. Distal bothridial surface divided by 21–22 (21 ± 1, n = 3) transverse septa delimiting 2 columns of 20–21 (20.5 ± 0.5, n = 3) loculi per column, anteriormost single loculus bearing apical sucker, and posteriormost loculi double, resulting of a total of 43–45 (44 ± 1, n = 3) loculi per bothridium; ( Fig. 4A, B , 6A, B , Table 1 ). Bothridial stalks shorts, fan-shaped. Cephalic peduncle distinct, muscular, 300–670 (417 ± 187, n = 5) long, 100–255 (188 ± 63, n = 5) wide.

Immature proglottids 7–21 (13 ± 5, n = 7) in number, initially wider than long, becoming longer than wide with maturity. Single terminal mature proglottid, longer than wide, 770–1,275 (997 ± 180, n = 6) long, 207–330 (278 ± 38, n = 6) wide, length to width ratio 2.7–4.8 (3.6 ± 0.7, n = 6): 1 ( Fig. 4A, C ). Single gravid proglottid, 1,275 (n = 1) long, 410 (n = 1) wide, length to width ratio 3.1(n = 1): 1. No detached gravid proglottids were seen.

Genital pores lateral, alternating irregularly, 27–32% (29 ± 2, n = 7) of proglottid length from posterior margin of proglottid. Testes oval, 44–59 (52 ± 6, n = 5) long, 32–52 (44 ± 8, n = 5) wide, 33‒47 (39 ± 6, n = 4) in number, arranged in 2–3 regular columns, 1 layer deep in cross section, each column extending from near anterior margin of proglottid to posterior margin of ovary. Genital atrium short, narrow ( Figs. 4A, C , 5A, B, C ). Cirrus sac elongate oval, slightly curved antero-medially from genital pore, thin walled, 75–107 (93 ± 17, n = 3) long, 42–57 (50 ± 7, n = 3) wide, extending to near midline of proglottid, containing cirrus unarmed ( Figs. 4C , 5B ). Vas deferens extending anteriorly from beyond the sac, entering cirrus sac anteriorly. Vagina simple tubular, extending medially from ootype, passing ventral and turning anteriorly to cirrus sac, opening into genital atrium anterior to cirrus; vaginal sphincter and seminal receptacle not observed ( Fig. 4C , 5A, C ).

Ovary lobulated, poral lobe 285–600 (405 ± 110, n = 6), aporal lobe slightly shorter than poral lobe, 270–590 (408 ± 115, n = 6) long, maximum width 100–160 (133 ± 21, n = 6), H-shaped in dorso-ventral view, tetralobed in cross-section at level of ovarian isthmus ( Figs. 4C , 5C ). Vitellarium follicular; vitelline follicles wider than long, 25–35 (28 ± 7, n = 4) long, 17–28 (22 ± 4, n = 4) wide, 1–2 dorsal and 1–2 ventral columns on each lateral margin of proglottid, not interrupted by ovary ( Figs. 4A, C , 5A, B, C ). Mehlis’ gland posterior to ovarian isthmus. Uterus saccate, ventral, extending to near anterior third of proglottid; uteroduct observed ( Figs. 4C , 5C ). Osmoregulatory ducts 4, 1 dorsal and 1 ventral pairs, medial to vitelline follicles.

Figures

FIGURE 4. Caulobothrium pieroi n. sp. from Pseudobatos horkelii (Müller and Henle), line drawings. A—Mature worm (holotype MACN-Pa No. 779). B—Scolex (holotype MACN-Pa No. 779). C—Terminal proglottid (paratype MACN-Pa No. 780/1).

FIGURE 5. Caulobothrium pieroi n. sp. from Pseudobatos horkelii (Müller and Henle), light micrographs of cross sections of a mature proglottid. A—Anterior to genital atrium. B—At the level of the genital atrium. C—posterior to the cirrus sac. D—At the level of the ovarian isthmus. Abbreviations: cs—cirrus sac, ov—ovary, t—testis, ud—uteroduct, ut—uterus, vf—vitelline follicle, vg—vagina, vod—ventral osmoregulatory duct.

FIGURE 6. Light micrographs of Caulobothrium species from the southwestern Atlantic. A—Caulobothrium pieroi n. sp., detail of the anterior loculus with apical sucker (arrow) (holotype MACN-Pa No. 779). B—Caulobothrium pieroi n. sp., detail of the posterior loculus (double) (paratype MACN-Pa No. 780/2). C—Caulobothrium uruguayense, showing two columns of paired loculi (arrows) (paratype USNM No. 1371263). D—Caulobothrium ostrowskiae, anterior portion of bothridium showing a single anteriormost loculus (paratype USNM No. 1371264).