Acanthobothrium westi , Vardo-Zalik, Anne M. & Campbell, Ronald A., 2011

Vardo-Zalik, Anne M. & Campbell, Ronald A., 2011, Five new species of Acanthobothrium van Beneden, 1849 (Cestoda: Tetraphyllidea) in elasmobranchs from the northwest Atlantic and Gulf of Mexico with first records from smooth-hound sharks and , Zootaxa 2838, pp. 41-64: 57-61

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Acanthobothrium westi

sp. nov.

Acanthobothrium westi  sp. nov.

( Figs. 25 –30View FIGURES 25 – 30, 32, 33View FIGURES 31 – 36)

Specimens deposited: holotype ( USNPCAbout USNPC 103841) and paratypes ( USNPCAbout USNPC 103838, 103840, 103843 –103845, 103847).

Host: Raja texana Chandler, 1921  ; Roundel skate; Rajiformes  : Rajidae  .

Type Locality: western Gulf of Mexico, 28 º 13.40 ’ N, 94 º 43.15 ’ W at depth of 27.5 fathoms. 23. x. 94, coll. R. A. Campbell.

Other localities: 27 º 58.57 ’N, 95 º 21.61 ’ W at 35 fathoms, 20. x. 94; coll. R.A. Campbell.

Site of infection: spiral intestine.

Prevalence: 2 of 11 individuals examined.

Etymology: the species is named after Dr. Warwick R. West, mentor to RAC and former chairman of the Department of Biology, University of Richmond for his guidance and support.

Description: Based on measurements of 8 whole mounted specimens. Small cestodes 1520 – 2340 (1950, n= 7) long, strobila consisting of 5–11 (10, n= 7) acraspedote segments, euapolytic. Scolex 215–277 (241, n= 7) long by 200–240 (224, n= 7) wide composed of 4 triloculate bothridia free at posterior ends; each bothridia with pad and apical sucker, and armed with one pair of bifid hooks. Bothridia 182–232 (216, n= 12) long by 82–128 (102, n= 12) wide, rounded posteriorly, joined by a velum ( Fig. 25View FIGURES 25 – 30), covered with filitriches and spinitriches over proximal surfaces and bothridial margins, divided into three loculi by thin muscular septa. (BL: BW) 1.75: 1 to 2.3: 1. Anterior loculus 72–123 (99, n= 12) long, middle loculus 35–49 (41, n= 12) long, posterior loculus 27–42 (32, n= 12) long. Ratio of locular lengths (A: M: P) 1: 0.29: 0.26 to 1: 0.35: 0.26. Apical pad 80–99 (91, n= 14) wide, bearing a single accessory sucker 23–36 (31, n= 14) in diameter. Cephalic peduncle 216–480 (265, n= 7) by 76–85 (82, n= 7) wide, covered with spinitriches. Ratio of bothridial length to cephalic peduncle length (BL: CPL) 1: 1.14 to 1: 2.4.

Hook dimensions: Hooks delicate, dissimilar in form. Lateral hook (n= 8): A= 25–28 (26); B= 42–53 (48); C= 38–48 (44); D= 63–72 (68); E= 63–73 (66); W= 34–48 (42). Medial hook (n= 8): A’ = 23–25 (24); B’= 49–57 (53); C’= 38–48 (43); D’= 69–76 (73); E’= 63–72 (67); W’= 32–49 (41). (THL: BL) 1: 2.5 to 1: 2.6.

Strobila: Immature segments wider than long, 4–9 (6, n= 8) in number, elongating with maturity. Mature segments 500–624 (570, n= 13) long by 160–224 (195, n= 13) wide, 1–3 (2, n= 8) per worm. Genital pores 45–56 % (50 %, n= 10) of segment length from posterior extremity, irregularly alternating. Genital atrium indistinct. Cirrus sac postequatorial, 72–84 long by 72 to 80 wide, pyriform in early segments, subspherical in oldest segments, tilted slightly posteriorly. Cirrus armed. Testes preovarian, 20–24 (22, n= 22) per segment, subspherical, 30–48 long by 19–38 wide, in two, single-layered columns, extending from anterior margin of ovary to near anterior extremity of segment. Testis distribution 7–10 (7.7, n= 22) preporal, 2–3 (2.8, n= 22) postporal, 10–13 (10.7, n= 22) aporal. Vagina anterior to cirrus sac, thick walled, arches from genital pore along anterior margin of cirrus sac to midline, turns posteriorly descending to join oviduct posterior to ovarian isthmus. Vaginal sphincter absent. Seminal receptacle not observed. Ovary posterior, 152–176 long by 57–88 wide, H-shaped, bilobed in cross section with 4–6 distinct pendulous lobules. Ovarian lobes nearly symmetrical, poral lobe often slightly (7 %) longer (154–179 by 27– 30) than aporal lobe ( Fig. 29View FIGURES 25 – 30), lobes may overlap posteriorly but not united. Mehlis’ gland posterior to ovarian isthmus, 17–23 long by 20–21 wide. Uterus median, tubular, thick walled, extending anteriorly about 79–85 % of segment length. Vitellarium follicular, in 2 lateral columns, each column 1–2 follicles wide, extending from anterior ovarian lobes to level of second testes anteriorly, interrupted by genital terminalia on poral side; follicles irregular in shape, c. 10–17 long by 7–13 wide. Excretory ducts lateral.

Remarks: Acanthobothrium westi  is a new category 1 species based on the criteria of Ghoshroy& Caira (2001). Distinguishing characters include the combination of small size, cephalic peduncle length, preovarian disposition of the testes, testis number, short extent of the ovarian lobes, and hook dimensions in contrast to other category 1 species. Compared to category 1 species in Atlantic coastal waters of the United States the presence of postporal testes and fewer testes (20–24 vs. 36–54) differentiates A. westi  from A. fogeli  ; it has fewer postporal testes (2–3 vs. 5–10) than A. lineatum  ; A. westi  has fewer testes (20–24 vs. 30–46), and fewer segments (5–11 vs. 5– 60) than A. lintoni  ; and it differs from A. paulum  by fewer segments per strobila (5–11 vs. 22–50), fewer antiporal testes (10–13 vs. 17–34) and shorter ovarian lobes (108–154 vs. 620–676); A. westi  has fewer segments (5–11 vs. 17–26) and fewer testes (20–24 vs. 38–57) than A. himanturi  ; it is smaller than A. marplatense  (<2.5 mm vs. 4.79– 8.44 mm) with fewer segments (5–11 vs. 18–30); and it is shorter than A. mathiasi  (2.5mm vs. 10–20 mm) which has bothridia longer than the cephalic peduncle. Acanthobothrium westi  differs from Category 1 species described herein by the following: A. westi  differs from A. lentiginosum  by possessing shorter total hook lengths (69–76 vs. 100–140) and the absence of testes between the ovarian lobes (compare Figs. 11View FIGURES 9 – 13 and 29View FIGURES 25 – 30); it differs from A. schalli  in the absence of testes between ovarian lobes; it differs from A. ulmeri  by numerous scolex features including total hook length (63–76 vs. 80–103), and bothridia consistently shorter than the longer cephalic peduncle (216–480 vs. 48–176) resulting in (BL: CPL) ratio of (1: 1.14–2.4 vs. 1: 0.15–0.4) and locular length ratio (A:M:P) of 1: 0.29– 0.35: 0.26 vs. 1: 0.4: 0.48.

Only a few species of Acanthobothrium  from the eastern Atlantic and Mediterranean Sea that closely resemble A. westi  are known well enough for critical comparison. In his review of the genus Williams (1969) pointed out the need for redescription of several species from the eastern North Atlantic similar to species described from elasmobranchs in the western North Atlantic. Among those descriptions are A. benedeni  and the large and small forms of A. filicolle  which may be a mix of species and remain unresolved. Of the recognizable species that are comparable, A. westi  lacks lappets on the bothridial margins seen in A. dujardinii  and A. edwardsi  . It also differs from A. minus  in lacking a vaginal sphincter and testes between the ovarian lobes; and it is distinguished from A. quadripartitum  and A. tripartitum  by possessing symmetrical ovarian lobes that do not reach the cirrus sac.

Acanthobothrium westi  can be distinguished from other category 1 species from the eastern Pacific as follows: from A. monksi  by smaller size (up to 2.3 mm vs. up to 7.6 mm) and fewer segments than A. monksi  and A. royi  (5– 11 vs. 24 –48, 19– 26 respectively); it differs from A. nicoyaense  by the lack of a vaginal sphincter and protruding genital pore; it has smaller bothridia (182–232 vs. 422–435) and smaller medial total hook length (69–76 vs. 163– 166) than A. atahualpai  ; and it differs from A. minusculum  and A. dollyae  in number of testes (20–24 vs. 6 –10, 42– 45 respectively).

Of the category 1 species from the Indo-Pacific region A. westi  differs from A. foulki  and A. larsoni  , A. marymichaelorum  , A. saliki  and A. southwelli  in the absence of postovarian testes and from A. guptai  by testis number (20–24 vs. 44–45). It lacks the horizontal band of musculature across the posterior loculi possessed by A. asnihae  and absence of postporal testes of A. gnomus  . Acanthobothrium westi  has a broader, rounder posterior loculus compared to the abruptly acuminate posterior loculus of Acanthobothrium lepidum Reyda & Caira, 2006  and it differs from A. oceanharvestae  , A. rowmanowi  and A. zimmeri  as follows: from A. zimmeri  in lacking postovarian testes; it is differentiated from A. rowmanowi  by testis number (20–24 vs. 34–53), posterior position of the genital pore, fewer segments (5–11 vs. 16–23) and smaller size (<2.5 mm vs. 4– 7.1 mm); and it differs from A. oceanharvestae  in number of postporal testes (2–3 vs. 6–11), testes between the longer ovarian lobes (176–182 vs. 380–711) which reach near the cirrus sac. Acanthobothrium westi  has fewer segments than A. zainali  (5-11 vs. 15–21).

Category 1 Australian species to be compared with A. westi  are: A. bartonae  , A. clarkae  , A. laurenbrownae  , A. martini  , A. odonoghuei  , A. rohdei  , A. pearsoni  and A. urolophi  . Acanthobothrium westi  differs as follows: it has shorter medial/lateral axial prongs (49–57 and 42–53 vs. 81–82 and 76–94) and lacks the hook tubercles present in A. bartonae  ; possesses fewer testes than A. clarkae  , A. laurenbrownae  , A. pearsoni  , and A. urolophi  (20–24 vs. 45 – 52, 31–46, 56–60, 34– 41 respectively) but more testes than A. martini  (20–24 vs. 8–11); it differs from A. mooreae  in the absence of a vaginal sphincter and smaller anterior loculus (72–123 vs. 147–175); A. odonoghuei  has testes distributed between the ovarian lobes and has a cephalic peduncle with very long hairlike microtriches, not observed in A. westi  ; it differs from A. rohdei  by in lacking a vaginal sphincter (present in A. rohdei  ) and the cirrus sac does not extend beyond the midline; and from A. stevensi  and A. thomasae  which have testes between the ovarian lobes.


United States National Parasite Collection