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 guitarfish, Zootaxa 2838, pp. 41-64: 57-61

publication ID

http://doi.org/ 10.5281/zenodo.206009

persistent identifier

http://treatment.plazi.org/id/0398B06F-5C76-E16D-F6E0-FBB9FEB1FD6B

treatment provided by

Plazi

scientific name

Acanthobothrium westi
status

sp. nov.

Acanthobothrium westi   sp. nov.

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

Specimens deposited: holotype ( USNPC 103841) and paratypes ( 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. 25 View 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. 29 View 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. 11 View FIGURES 9 – 13 and 29 View 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.

USNPC

United States National Parasite Collection