单孔科拟囊腔属吸虫一新种

One new species of Saccocoelioides (Digenea: Haploporidae) from Liza carinatus in Taiwan Strait

拟囊腔吸虫 ,新种Saccocoelioideslizaesp .nov .发现于棱 Lizacarinatus的消化道 .同已知种相比 ,无论虫体大小还是各器官的形态结构及分布 ,新种与S .magniovatusSzidat,1 954和Saccocoelioidesbeauforti(Hanter&Thomas,1 961 ;Over streef,1 971 )最为相似 .但S .magniovatus没有前咽 ,虫卵 (0 .0 95～ 0 .1 1 4× 0 .0 41～ 0 .0 60 )较大且卵黄腺几乎呈“V”形 ;而Saccocoelioidesbeauforti的食道较长 ,肠叉位于腹吸盘之后 ,肠管止于卵巢之后 ,虫卵里的毛蚴不具眼点 .

The paper deals with a new species of Saccocoelioides Szidat, 1954 obtained from the intestine of Liza carinatus (Cuvier et Valenciennes). Type specimens are deposited in Parasitology Research Laboratory, School of Life Sciences, Xiamen University. Measurements are given in millimeters, as the ranges followed by the mean in parentheses, unless otherwise stated. Saccocoelioides lizae sp. nov. (PlateⅠ) Type host:Liza carinatus (Cuvier et Valenciennes). Prevelence and infectivity: 37.2% (105 infected/282 examined), 1～327 (12) helminths per fish. Site of infection: Intestine. Type locality: Jimei,Xiamen(24°25′24″～33′14″N, 118°03′58″～11′48″E), Fujian, China. Etymology: The specie name refers to its host Liza carinatus. Description (Based on 18 specimens): Body elliptical, broad at ovarian level, 0.690～0.990×0.300～0.406 (0.848×0.358). Tagument spinose from anterior end to near posterior end of body. Pigment distributed in forebody. Oral sucker subterminal, 0.080～0.106×0.092～0.128 (0.094×0.113). Acetabulum 0.094～0.110×0.080～0.120 (0.102×0.109), situated at the junction of anterior and middle third of body. Sucker ratio 1∶0.84～1.22 (1.04). Prepharynx 0.024～0.084 (0.058) long. Pharynx globular, 0.058～0.072×0.058～0.078 (0.063× 0.064 ). Esophagus 0.080～0.150 (0.119) long. Esophagus/Pharynx length ratio 1.3～2.6 (1.9)∶1 . Intestinal bifurcation at middle or anterior to acetabulum, and caeca ending anterior to ovary. Testis single, oval to spherical, 0.080～0.168×0.066～0.156 (0.119×0.119). Posttesticular space 0.130～0.374 (0.219) long. Harmaphroditic sac thick-walled, nearly rectangular, 0.110～0.160×0.076～0.136 (0.129×0.097), largely or entirely anterior to acetabulum; contents including tubular internal seminal vesicle, 0.064～0.152×0.016～0.032 (0.098× 0.022 ), with its anterior portion turning posteriorly; prostatic complex 0.020～0.040 (0.028) long; metraterm 0.020～0.030 (0.024) long; and muscular hermaphroditic duct, 0.054～ 0.110 ×0.029～0.048 (0.074×0.038), armed with spirally arranged pads. External seminal vesicle saccular to elongated, 0.062～0.140×0.016～0.072 (0.102×0.036). Genital pore median, anterior to acetabulum. Ovary oval to spherical, median, 0.030～0.050×0.030～0.054 (0.042×0.042), anterior to testis. Receptaculum seminis absence. Laurer's canal 0.200～0.284 (0.226) long, opening dorsally middle of posterior third of body. Vitellaria follicular, on each lateral side of middle third of body, arranged in irregular H～shaped. Uterus with descending and ascending limbs. Eggs large, 0.072～0.086×0.038～0.052 (0.078×0.047), elliptical transparent containing oculate miracidium. Excretory vesicle 'Y' shaped, with short stem which has a peculiar bulb consisting of very fine muscle fiber at subterminal part and narrow diverging crura extending to pharyngeal zone, excretory pore terminal. Discussion Since Szidat (1954) erected the genus Saccocoelioides for seven species of the genus collected from freshwater fishes of Argentina, several authors have noted its systimatics and species compositions. Yamaguti (1954) reduced Saccocoelioides to subgeneric status of Lecithobotrys Looss, 1902, but in 1971 he reinstated it to its original genetic position. Nasir & Gomez (1976) considered Saccocoelioides a synonym of Lecithobotrys. Travassos, Freitas & Kohn (1969), Kohn (1985) and Rekharani & Madhavi (1985) considered Saccocoelioides a valid genus. Up to now, there are 16 nominal species which have been attributed to the genus Saccocoelioides. These are: S. nanii Szidat, 1954, type species; S. elongates Szidat, 1954; S. magniovatus Szidat, 1954 [transferred to Lecithobotrys Looss, 1902 by Martin (1973)]; S. magnus Szidat, 1954; S. sp. 5 Szidat, 1954; S. sp. 6 Szidat, 1954; S. sp. 7 Szidat, 1954; S. sogandaresi Lumden, 1963 [not been accepted as a member of the genus Saccocoelioides by Thatcher (1978)]; S. szidati Travassos, Freitas & Kohn, 1969[denominated to S. sp. 6 Szidat, 1954 by Travassos, Freitas & Kohn, 1969]; S. octavus Szidat, 1970; S. beauforti (Han