Szidatitrema yamagutii, Dronen & Craig & Hammond, 2006

Dronen, Norman O., Craig, Thomas M. & Hammond, Elizabeth E., 2006, Szidatitrema yamagutii n. sp. (Digenea: Cyclocoelidae: Ophthalmophaginae) from the bearded barbet, Lybius dubius (Capitionidae), and the white-necked myna, Streptocitta albicollis (Sturnidae), that died at the Audubon Zoo in New Orleans, Louisiana, U. S. A., Zootaxa 1219 (1), pp. 59-68 : 61-64

Szidatitrema yamagutii n. sp.

( Figs. 1–5 )

Type host: Streptocitta albicollis (Vieillot, 1818) , Sturnidae ; the white­necked myna or Sulawesi magpie.

Additional host: Lybius dubius (Gmelin, 1788) , Capitionidae; the bearded barbet.

Type locality: Audubon Zoo in New Orleans , Louisiana, U.S.A. This is likely a species that was introduced from Sulawesi .

Site of infection: Air sacs of lungs and body cavity.

Number of worms present: Approximately 30– 40 adult worms from Streptocitta albicollis and from each of the Lybius dubius .

Deposited specimens: Holotype USNPC 96975 ; paratypes (1 specimens) HWML

48328; Voucher specimens (4 specimens) HWML 48329 , 48330 , 48331 .

Etymology

The species is named in honor of Dr. Satyu Yamaguti for his many contributions to our knowledge of the cyclocoelids and the genus Szidatitrema Yamaguti, 1971 .

Description

Based on 14 specimens (6 entire adult specimens, 7 damaged adult specimens and 1 sectioned specimen). With characteristics of the genus. Body moderately large, oval, (holotype specimen, 5.6mm) 6.6 (5.5–8.8)mm long by (1.6) 1.8 (1.6–2.1)mm wide at widest point (n=4). Oral sucker and acetabulum absent. Mouth slightly subterminal; prepharynx (measured as the distance from the opening of the mouth to the anterior margin of the pharynx) (50) 60 (40–80) long; pharynx well developed, (240) 260 (230–320) long by (210) 215 (200–290) wide; esophagus longer than prepharynx (measured as actual length), (230) 295 (230–400) long. Ceca simple, uniting near posterior extremity to form cyclocoel. Genital pore generally postpharyngeal, opening ventrally near midline of body, but located at level of posterior fourth of pharynx in many specimens. Testes smooth, spherical to subspherical, somewhat oblique, located in intercecal region in posterior fourth of body. Anterior testis in anterior aspect of posterior quarter of body, (330) 405 (330–520) long by (380) 375 (330–420) wide. Posterior testis located in posterior seventh of body, (370) 435 (370–530) long by (360) 370 (290–420) wide. Cirrus sac (300) 345 (250–440; approximately 5% of body length) long by (170) 130 (100–170) wide (n=6). Ovary smooth, oval, dextral and posterior to posterior testis in some specimens, but more adjacent in most with its center at level of posterior extremity of posterior testis, contiguous with cyclocoel posteriorly, forming elongated triangle with testes, (280) 275 (220–370) long by (270) 260 (220–330) wide. Postovarian space (410) 590 (400–820 long; approximately 10% of body length) (n=5). Seminal receptacle located between ovary and posterior testis at level of posterior margin of posterior testis. Laurer’s canal absent. Ootype located immediately sinistral to seminal receptacle. Details of the female reproductive system were not visible. Vitelline follicles distributed laterally along ceca from level of esophagus to near posterior extremity, not confluent posteriorly. Uterus extensive, with extracecal loops common in posterior two thirds of body. Eggs in anteriormost loops of uterus, (104) 97 (80–105) long by (46) 45 (40–55) wide (n=30). Miracidia nonoculate. Excretory vesicle simple, anterior extent not visible. Excretory pore terminal.

Remarks

The new species has a posttesticular ovary that forms a triangle with the testes, a genital pore that is postpharyngeal, vitelline fields that are not united posteriorly, and it has extracecal uterine coils that do not surpass the vitelline fields, placing it in Szidatitrema .

Currently, there are 2 nominal species of Szidatitrema : S. philomachii ( India) and S. vogeli ( Liberia) . Szidatitrema yamagutii n. sp. can be distinguished from both of these species by having a smaller egg size (80–105 by 40–55 compared to 117–126 by 54–72 and 110 by 50, respectively) and the placement of the testes in S. yamagutii n. sp. relative to one another is less oblique, where the anterior testis is not contiguous with the cecum. The new species further differs from S. philomachii by lacking an oral sucker and having larger testes (anterior testis 405 by 375 compared to 270 by 210; posterior testis 435 by 370 compared to 225 by 210). The new species is most similar to S. vogeli in general body morphology, but it further differs from this species by having a shorter cirrus sac (345 compared to 554), somewhat smaller testes (anterior testis 405 long compared to 700; posterior testis 435 long compared to 500), a smaller ovary (220–330 wide compared to 400) and a larger postovarian space (approximately 10% of body length compared to 6% [calculated from Szidat’s figure]).

Gupta (1964) described Ophthalmophagus mertensis Gupta, 1964 from the body cavity of the common sandpiper, Actitis hypoleucos (Linnaeus, 1758) from India, but this species has a postpharyngeal genital pore and vitelline fields that are not confluent posteriorly, and therefore should not be assigned to Ophthalmophagus . The placement of this species in an existing genus of Ophthalmophaginae where the genital pore is postpharyngeal and the vitelline fields are not united posteriorly ( Spaniometra , Szidatitrema ) is difficult. Ophthalmophagus mertensis is like species of Szidatitrema by having testes that are not arranged in a straight line with the ovary; however, it is unlike species of this genus by having testes that are tandem rather than being oblique and O. mertensis has a very extensive intertesticular space. Although O. mertensis is somewhat like species of Spaniometra by having tandem testes, unlike species in this genus, the testes in O. mertensis are situated on the left side of the posterior third of the body rather than forming a straight line with the ovary and being situated in the middle third of the body, and the uterine coils in O. mertensis are intertesticular rather than extending laterally beyond the ceca and vitelline fields as is seen in species of Spaniometra . This species may represent an undescribed genus in Ophthalmophaginae .

Figures

FIGURES 1–4. Szidatitrema yamagutii n. sp. from the bearded barbet, Lybius dubius. 1. Dorsal view of adult. 2. Enlarged photograph of opening of genital pore, ventral view. 3. Photograph of pharyngeal region showing location of the cirrus sac relative to pharynx, ventral view. 4. Drawing of terminal genitalia. Abbreviations C, cecum; GP, genital pore; P, Pharynx; SV, seminal vesicle; U, uterus. Scale bars: 1, 1,200µm; 2, 150µm; 3, 350µm; 4, 350µm.

FIGURE 5. Picture of a bearded barbet, Lybius dubius showing Szidatitrema yamagutii n. sp. in place. Abbreviation AF, adult flukes.