R Bray, A Gaevskaya - Bathymonorchis polyipni reimer 1985 n g n comb digenea monorchiidae from bathypelagic fishes of the eastern mid-atlantic ocean - страница 1
Systematic Parasitology 26: 91-95, 1993.
© 1993 Kluwer Academic Publishers. Printed in the Netherlands.
Bathymonorchis polyipni (Reimer, 1985) n. g., n. comb. (Digenea: Monorchiidae) from bathypelagic fishes of the eastern mid-Atlantic Ocean
Rodney A. Bray1 and Albina V. Gaevskaya2
'Department of Zoology, The Natural History Museum, Cromwell Road, London SW 7 5BD, UK ^Institute of Biology of the Southern Seas, Academy of Sciences of Ukraine, 2, Nakhimov St., Sevastopol 335000, Ukraine
Accepted for publication 28th October, 1992 Abstract
The new genus Bathymonorchis is defined and differentiated from the genera Monorchis and Allolasi-otocus. B. polyipni (Reimer) n. comb., previously attributed to Monorchis, is described from Neoscopelus macrolepidotus and Polymetme corythaeola from the Atlantic off the coast of NW Africa. The new genus is characterised by its single vitelline field, multilobate ovary, spinous blind portion of Looss' organ, lack of external seminal vesicle, testicular position and uterine configuration.
It has been shown that there are relatively few endemic digeneans in meso- and bathypelagic fish species (Noble & Collard, 1970; Gartner & Zwerner, 1989), but in this paper we report the presence of a new genus of monorchiid digenean from myctophiform and salmoniform mid-water species.
Materials and methods
The specimens were fixed flattened or unflattened in formalin, stained by various methods and mounted in Canada balsam. Serial sections were stained in eosin and Mayer's haemalum and mounted in thin Canada balsam. Measurements are quoted in micrometres throughout as the range with the mean in parentheses.
Family Monorchiidae Odhner, 1911
Subfamily Monorchiinae Odhner, 1911 Genus Bathymonorchis n. g.
Monorchiidae, Monorchiinae. Body fusiform. Tegument spinous. Oral sucker subglobular, subter-minal. Prepharynx usually visible. Pharynx small. Oesophagus short to long. Intestinal bifurcation in mid-forebody. Caeca long, terminate blindly well into hindbody. Ventral sucker rounded, in anterior half of body. Testis one; elongate-oval; lateral, in posterior third of body. Cirrus-sac large. Seminal vesicle internal; saccular. Pars pro-statica narrow. Ejaculatory duct wide, lined with long, narrow spines. Genital pore ventro-median, in posterior forebody. Ovary multilobate, lateral at level of ventral sucker. Uterine seminal receptacle present. Uterus coiled throughout hindbody, enters middle of Looss' organ. Looss' organ large, spined in blind and distal parts. Vitellarium follicular; follicles large, in single field across posterior
half of forebody. Excretory pore terminal; vesicle not seen.
Type-species: Bathymonorchis polyipni (Reimer, 1985) n. comb.
Bathymonorchis polyipni (Reimer, 1985) n. comb.
Synonym: Monorchis polyipni Reimer, 1985. Material studied
ex Neoscopelus macrolepidotus Johnson, Neosco-pelidae, Myctophiformes. Rectum. Atlantic Ocean off Western Sahara (23-27° N, 13-17° W, depth 590-600m, March 1974). Collector: A.V. Gaevskaya. BM(NH) Reg. No. 19184.108.40.206. ex Polymetme corythaeola (Alcock), Photichthyi-dae, Salmoniformes. Intestine. Atlantic Ocean off Morocco (34° N, 09° W, depth 360-408 m, 14 January 1971). Collector: R.A. Bray. BM(NH) Reg. No. 19220.127.116.11.
Based on 16 flattened specimens from TV. macrolepidotus, 2 of which were subsequently sectioned, and one unflattened from P. corythaeola, also subsequently sectioned. Measurements on 14 specimens from N. macrolepidotus.
Body fusiform, widest at level of ventral sucker; 1,640-2,650 x 630-920 (2,281 x 801) (Fig. 1). Width 24-52 (36)% of length. Tegument spinous throughout; spines more widely spaced in hindbody (but lost in several specimens). Oral sucker subterminal; subglobular; walls thin; 142185 x 125-194 (157 x 168). Ventral sucker rounded; muscular walls thin; 178-220 x 158-209 (203 x 188). Sucker-ratio 1:0.95-1.42 (1.13). Forebody 26-44 (34)% of body-length. Prephar-ynx usually distinct, occasionally not visible; 0-38 (16). Pharynx oval; small; 70-101 x 61-82 (82 x 67). Oral sucker: pharynx width ratio 1:0.36-0.50 (0.40). Oesophagus long, narrow; 95310 (231). Intestinal bifurcation in mid-forebody; 201-448 (315) from ventral sucker. Caeca narrow; reach to mid-hindbody or just beyond; terminate blindly; posterior extremity obscured by eggs in whole-mounts.
Excretory pore terminal. Vesicle obscured by eggs, even in sectioned specimens.
Testis single; longitudinally elongate-oval; margin may be indented by configuration of adjacent uterus; in posterior third of body, lying close to left or right lateral margin, usually on opposite side of body to ovary (on same side in one specimen), occasionally difficult to see in specimens replete with eggs; 340-630 x 89-159 (479 x 123). Cirrus-sac large; claviform; lying dorsally or laterally to ventral sucker, reaching into anterior hindbody; 310-492 x 83-140 (396 x 106) (Fig. 2). Seminal vesicle internal; oval, saccular. Pars pro-statica narrow; surrounded by large irregular gland-cells. Ejaculatory duct distinct, wide; lined with numerous, distally pointing, narrow, filamentous spines of up to 80 long. Genital atrium distinct, tubular. Genital pore median; close to anterior margin of ventral sucker.
Ovary multilobate, longitudinally elongate-oval; lies laterally, either sinistrally or dextrally, at level of ventral sucker or just anterior; 127— 460 x 61-120 (254 x 92). Laurer's canal apparently runs posteriorly from ovary; dorsal aperture not seen. Proximal coils of uterus form uterine seminal receptacle. Uterus extensive; coils fill most of hindbody and may reach into lateral regions of posterior forebody. Eggs numerous; small, 19-23 x 9-14 (21 x 12); tanned; opercu-late. Looss' organ claviform; widest proximally; with thicker wall distally; 145-234 x 76-108 (200 x 92); lined with numerous filamentous spines of up to 70 long in blind proximal portion and up to 50 long in distal portion. Uterus enters Looss' organ at about middle of median margin (Fig. 2). Vitellarium follicular; follicles large, irregular with tendency to be elongate longitudinally; in single field reaching across posterior half of forebody; ventral to caeca and oesophagus; reaching to about mid-oesophagus, 39-228 (118) from pharynx.
Measurements of single specimen from P. corythaeola (taken prior to sectioning): Body 1,475 x 420. Width 28% of length. Oral sucker 114 x 142. Ventral sucker 145 x 159. Sucker-ratio 1:1.12. Forebody 32% of body length. Prephar-
Figs 1-2. Bathymonorchis polyipni (Reimer) n. comb, from Neoscopelus macrolepidotus. 1. Ventral view of flattened worm. 2. Terminal genitalia. Scale-bars: 1, 500 \i.m; 2, 200 \x.m.
ynx not seen. Pharynx 71 x 44. Oral sucker: pharynx ratio 1:0.31. Oesophagus at least 135; intestinal bifurcation obscured by eggs. Testis obscured by eggs. Cirrus-sac 340 x 75. Looss' organ 165 x 74. Ovary 138 long, width obscured by eggs. Eggs 21-22 x 12-16.
Type-host and locality: Polyipnus spinosus, Indian Ocean, Mozambique Channel. Records: 1. Reimer (1985); 2. Present study. Definitive hosts: Neoscopelidae: Neoscopelus macrolepidotus (2). Photichthyidae: Polymetme [or Yarella] corythaeola (1,2). Sternoptychidae: Polyipnus spinosus (1).
Distribution: FAO Fisheries Areas 34 Atlantic, E Central [off Western Sahara (2), off Morocco (2)], 51 Indian Ocean, W [Mozambique Channel (1)].
The family Monorchiidae includes well in excess of 50 described genera, whose relationships and supra-generic systematics are not well worked out. The family is considered polyphyletic by Brooks, O'Grady & Glen (1985), and Cable (1974) considered some of the freshwater forms to be closer to the marine zoogonids than to the marine monorchiids. The latest summaries of the systematics of the family are by Mamaev (1968) and Yamaguti (1971). Mamaev (1968) discussed the history of the family, the status of the subfamilies proposed by various authors and reviewed some of the characters, stating, for example, that the number of testes (one or two) is not a subfamily character and that the point of entry of the uterus into Looss' organ is not a generic character.
We have examined all described genera and have found our new genus to be closest to Monorchis Looss, 1902 and Allolasiotocus Yamaguti, 1959.
Bathymonorchis differs from Monorchis spp. in the following characters: (1) vitellarium in a single field rather than two separated fields; (2) ovary multilobate rather than globular, lobed or irregular; and (3) spines present in blind proximal portion of Looss' organ. In addition to specimens of
Monorchis monorchis (Stossich, 1890), we have consulted the descriptions of Monorchis monorchis [syn: M. parvus Looss, 1909] by Naid-enova & Gaevskaya (1978) and Radujkovic, Orec-chia & Paggi (1989), of M. hermanni Issa, 1963 by Issa (1963), of M. japonicus Zhukov, 1970 by Zhukov (1970), of M. minutus Madhavi, 1977 by Madhavi (1977), of M. diplovarium Mamaev, 1970 by Mamaev (1970), of M. heterorchis Bilqees, 1980 by Bilqees (1981) and of M. fusi-formis Wang, 1982 by Wang (1982).
Bathymonorchis differs from Allolasiotocus spp. by the following characters: (1) lack of an external seminal vesicle; (2) vitellarium in a single field rather than two separated fields; (3) testis close to posterior extremity rather than adjacent to ovary and ventral sucker; (4) bulk of uterus pre-testicular rather than post-testicular; (5) lack of a three-chambered genital atrium lined with 'bristles'; and (6) ovary multilobate rather than irregular or with few lobes. We have consulted the descriptions of Allolasiotocus nibeae Yamaguti, 1959 of Yamaguti (1959) and A. pseudoscia-enae Wang, 1982 of Wang (1982).
The species Monorchis polyipni Reimer, 1985 was described from two teleost species of the order Salmoniformes from the Indian Ocean in the Mozambique Channel (between 21°06' and 24°54' S, depth 420-605 m) (Reimer, 1985). Our specimens show slight, but insignificant, differences to Reimer's description. Professor Reimer kindly lent us three specimens of M. polyipni which, on examination, were found to be practically indistinguishable from our specimens. The oesophagus, which appeared to be shorter judging by Reimer's description, was seen clearly in only one of Reimer's contracted specimens, but in that case it measured 167 long. The contracted condition of the Indian Ocean worms also, we believe, contributes to the apparent difference in the anterior extent of the vitellarium.
We are indebted to Professor L. Reimer of the University of Rostock, Germany, for the loan of
A пё* monorchiid genus from bathypelagic fishes 95
specimens. The visit of AVG to Britain was partly funded by The Royal Society. We would like to thank Dr D.I. Gibson for reading the manuscript and Mr D.W. Cooper for the preparation of serial sections.
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