Omar M. Amin

KEY TO THE FAMILIES AND SUBFAMILIES OF ACANTHOCEPHALA, WITH THE ERECTION OF A NEW CLASS (POLYACANTHOCEPHALA) AND A NEW ORDER (POLYACANTHORHYNCHIDA)

A key to the classes, orders, families, and subfamilies of Acanthocephala based on the Meyer-Van Cleave system as presented by Amin (1985) is provided. A new class (Polyacanthocephala) and a new order (Polyacanthorhynchida) are erected to accommodate members of the monogeneric family Polyacanthorhynchidae Golvan, 1956.

ACANTHOCEPHALA FROM LAKE FISHES IN WISCONSIN: ECOLOGY AND HOST RELATIONSHIPS OF POMPHORHYNCHUS BULBOCOLLI (POMPHORHYNCHIDAE)

Pomphorhynchus bulbocolli Linkins in Van Cleave, 1919, was considerably more common in fishes of the river-connected Tichigan Lake than of the landlocked Silver Lake, southeastern Wisconsin. It is reported from 17 species of principal, accessory, and occasional definitive hosts (new record in Moxostoma carinatum) and from 13 species of paratenic hosts (new records in Amia calva, Ictalurus punctatus, Lepomis cyanellus, and Pomoxis nigromaculatus). Infection patterns were influenced by fish species, feeding behavior, temperature, availability of intermediate host, type of water body, fish movement, and changes in fish host community. Host roles are not fixed but are often interchangeable. A seasonal cycle in prevalence, intensity, and maturation was evident, with greatest abundance and maturation during summer and recruitment during summer and autumn. Recruitment of new infections, development, and release of eggs, however, occurred all year. Sex ratio changed from near equal in new infections to one more highly in favor of females in older adults. Female fish were considerably more frequently and heavily infected than males. No relationship with fish age (size) was evident. Worms were mostly attached in posterior intestinal locations but initial establishment sites correlated with temperature. Translocation of P. bulbocolli due to competitive exclusion in concurrent infections was not observed. The significance of extraintestinal larval forms in the cycle of transmission was noted.

ON THE CRUSTACEAN HOSTS OF LARVAL ACANTHOCEPHALAN AND CESTODE PARASITES IN SOUTHWESTERN LAKE MICHIGAN

A total of 11,875 crustaceans of 2 species, Pontoporeia affinis (Lindstrom) (Amphipoda) and Mysis relicta (Loven) (Mysidacea) from bottom samples as well as from the stomachs of slimy sculpins, Cottus cognatus Richardson, was dissected in search of certain larval helminth parasites. Pontoporeia affinis was found infected with larval Echinorhynchus salmonis Muller 1784 (Acanthocephala) (new cystacanth geographical record in Lake Michigan), Acanthocephalus parksidei Amin 1974 (Acantho- cephala) (first record of an intermediate host for A. parksidei) and Cyathocephalus truncatus Pallas 1781 (Cestoda) (first procercoid record in the United States). One M. relicta also was infected with C. truncatus (new host record). Frequency of infection with these parasitic species was extremely low although some- what higher, particularly in P. affinis females, from sculpins than from bottom samples. Most C. truncatus procercoids were gravid and progenesis of this species in North American P. affinis, along with other findings, is discussed.

INTESTINAL HELMINTHS OF SOME NILE FISHES NEAR CAIRO, EGYPT WITH REDESCRIPTIONS OF CAMALLANUS KIRANDENSIS BAYLIS 1928 (NEMATODA) AND BOTHRIOCEPHALUS AEGYPTIACUS RYSAVY AND MORAVEC 1975 (CESTODA)*

Of 10 species of Nile fishes collected during the summer of 1975 at Giza near Cairo, Egypt, 7 harbored 7 helminth species. Recovered material includes 3 species of nematodes: Camallanus kirandensis Baylis 1928 (new host and geographical record), Cucullanus barbi Baylis 1923, and Rhabdochona congolensis Campana-Rouget 1961 (new host record); three species of cestodes: Khawia sp. (new in Africa), Polyonchobothrium clarias (Woodland 1925) Meggitt 1930, and Bothriocephalus aegyptiacus Rysavý and Moravec 1975; and one acanthocephalan species, Acanthosentis tilapiae Baylis 1947 (new geographical record). Morphologic observations of each species are reported. C. kirandensis and B. aegyptiacus are redescribed.

Variability in Acanthocephalus parksidei Amin, 1974 (Acanthocephala: Echinorhynchidae)

Acanthocephalus parksidei Amin, 1974, was recently described from 11 species of Wisconsin fishes. Considerable variation was observed in this acanthocephalans body size, number and arrangement of proboscis hook, size of hooks, proboscis, proboscis receptacle, lemnisci, embryos, testes, and cement glands, and number of the latter two. Most of these variations were related to worm sex and age as well as host species. Structural variations in the shape and lobation of lemnisci, abnormalities in hooks and body wall, and changes associated with monorchidism in males were noted. The significance of the erection of this new taxon in relation to the taxonomic criteria applied to acanthocephalan species is discussed.

Host and Seasonal Associations of Acanthocephalus parksidei Amin, 1974 (Acanthocephala: Echinorhynchidae) in Wisconsin Fishes

Ecological associations of Acanthocephalus parksidei Amin, 1974, were studied in 11 southeastern Wisconsin fishes during 1972-73. Parasitic load was found to be related to host species, size (age), sex, concurrent infections, collection site, and season. Distribution in host intestine was related to the extent or intensity of infection, posterior migration, and concurrent infections. Parasitic cycle commenced in later summer-early autumn, peaked (in frequency and maturation) during the spring, and terminated in the late summer.

ACANTHOCEPHALA FROM LAKE FISHES IN WISCONSIN: HOST AND SEASONAL DISTRIBUTION OF SPECIES OF THE GENUS NEOECHINORHYNCHUS HAMANN, 1892

r: Five species of Neoechinorhynchus are reported, not including Neoechinorhynchus robertbaueri Amin, 1985, which was described elsewhere. Of 14 species of fish infected with Neoechinorhynchus cylindratus (Van Cleave, 1913) Van Cleave, 1919, from Silver and Tichigan Lakes, Micropterus salmoides, Micropterus dolomieui and Esox lucius were the principal definitive hosts. Lepomis macrochirus may be a second intermediate host in its life cycle. Most recruitment occurred in late summer and in autumn, sexual development and breeding by spring, and growth and elimination of ripe eggs by summer. A partial overlap of generations was observed in the autumn. Neoechinorhynchus prolixoides mostly infected Erimyzon sucetta but was also found in M. salmoides, M. dolomieui, Pomoxis nigromaculatus, Stizostedion vitreum, Pimephalus promelas (all new host records) and Moxostoma erythrurum; new state record for Wisconsin. Measurements of Neoechinorhynchus prolixoides were provided and comparison is made with the original description. Extension of its binucleate lemniscus relative to anterior testis margin is not a good diagnostic character. The seasonal periodicity of N. prolixoides bore basic similarities to that of N. cylindratus but involved more juveniles, particularly in the spring, and its simultaneous growth and maturation produced the highest adult intensity index during the summer. The smaller land-locked Silver Lake was considerably more heavily populated by both species than the larger riverconnected Tichigan Lake. Both species showed significant but limited posterior migration in the intestine of their major hosts by the summer. Their intestinal distribution was compared with sites occupied by other helminth species in concurrent infections. Host sex did not affect worm burden, but size did. Neoechinorhynchus rutili (Muller, 1780) Hamann, 1892 and Neoechinorhynchus strigosus Van Cleave, 1949 were also recovered from Culaea inconstans and Catostomus commersoni, respectively. Neoechinorhynchus salmonis Ching, 1984 is reported for the first time in the U.S., from Lepomis cyanellus (new host species and family records) that was recovered earlier from the Pike River, which drains into Lake Michigan. The descriptions of Fessisentis tichiganensis from Tichigan Lake (Racine County) and of Neoechinorhynchus robertbaueri from Silver Lake (Kenosha County) by Amin (1980 and 1985, respectively) constitute the first 2 of this series of reports on acanthocephalans from lake fishes in southeastern Wisconsin. Four other species of Neoechinorhynchus are reported herein from the above 2 lakes with emphasis on the host and seasonal distribution of the more common 2, Neoechinorhynchus cylindratus (Van Cleave, 1913) Van Cleave, 1919 and Neoechinorhynchus prolixoides Bullock, 1963. The Neoechinorhynchus sp. reported by Amin (1975) from Lepomis cyanellus Raf. in the Pike River, which drains into Lake Michigan, is herein assigned to Neoechinorhynchus salmonis Ching, 1984 and discussed. A number of new host and state records are noted. Received 29 April 1985; revised 9 August 1985; accepted 21 August 1985. MATERIALS AND METHODS Seasonal parasitological collections were made from Silver Lake (Kenosha County) and Tichigan Lake and canal (Racine County) during the spring (April, early May), summer (June, July, early August) and autumn (late October, November) between 1976 and 1984. The 188-ha Silver Lake has a maximum depth of 13.4 m. It is an eutrophic land-locked lake of glacial origin lying within the lateral moraine of the Lake Michigan lobe of the Wisconsin glacier. A small outlet historically permitted the intermittent discharge of overflow waters (until dammed in 1932) into the Fox River, a tributary of the Mississippi River drainage system. Silver Lake was probably originally populated by fish and parasite faunas of Mississippi River origin. The size of the eutrophic Tichigan Lake, originally a natural lake on the above Fox River, increased to 458 ha as a result of an impoundment of the Fox River in 1830; it has a maximum depth of 19.2 m. Fishes were routinely collected and specimens processed and measured as described by Amin (1985). All measurements are in micrometers, with averages in parentheses, unless otherwise noted. Mean per host is the number of parasites recovered/number of fishes examined. The site of infection was determined in host alimentary regions as footnoted in Tables V and VIII. Juveniles are recently recruited young adults with in-

Taxonomic notes on Polyacanthorhynchus kenyensis (Acanthocephala: Polyacanthorhynchidae) from Lake Naivasha, Kenya.

The original description of Polyacanthorhynchus kenyensis Schmidt and Canaris, 1967 from 2 species of fish in Lake Naivasha, Kenya was primarily based on measurements of 2 male cystacanths. That description is herein emended based on the availability of a larger number of immature worms of both sexes obtained from the freshwater teleosts Orechromis leucostictus, Tilapia zillii (new paratenic host records), and Micropterus salmoides. A secretory function for the apical organ is suggested.

Acanthocephala from lake fishes in Wisconsin: morphometric growth of Pomphorhynchus bulbocolli (Pomphorhynchidae)

The trunk, proboscis, basal proboscis hooks, neck (exclusive of bulb), bulb, basal hooks, anterior testis, and eggs of Pomphorhynchus bulbcolli Linkins in Van Cleave, 1919, were studied in 7 length classes of worms ranging between 2 and 16 mm. All structures, except proboscis hooks, showed progressive and continuous growth corresponding with increase i omomn worm length. Growth was most rapid in worms shorter than 6 mm including mostly immatures. Females smaller than 6 mm had no eggs. Eggs and proboscis hooks in worms longer than 6 mm were sufficiently stable to be of reasonable taxonomic value. Growth in bulb diameter and length of proboscis hooks and neck appear essential for the special attachment mechanism characteristic of P. bulbocolli. The small size of these structures in recently ingested immatures permits the freedom to disengage, move, and reattach. Within 2-3 wk, these structures reach considerable size in worms ca. 6 mm long. Once secured, maturation and reproductive activity become evident as growth slows down. The reported study provides a reference line against which a comparison with other species, e.g., P. rocci Cordonnier and Ward, 1967, may be made.

ACANTHOCEPHALA FROM LAKE FISHES IN WISCONSIN: NUMERICAL AND STRUCTURAL-FUNCTIONAL RELATIONSHIPS OF THE GIANT NUCLEI IN NEOECHINORHYNCHUS CYLINDRATUS (NEOECHINORHYNCHIDAE)

Numerical and structural variations in the giant nuclei of Neoechinorhynchus cylindratus collected from Micropterus salmoides and Esox lucius in Silver Lake (Kenosha County), Wisconsin, were systematically studied. The number of nuclei (usually 17 in males and 9 in females) in the population examined was correlated with host species, season, sex and developmental stage. Structural changes observed in all giant subcuticular, lemniscal (in both sexes) and cement gland, nuclei (in males) corresponded with initiation, continuation and termination of reproductive activity of worms. Both morphological and positional changes of the nuclei in each of 5 developmental stages are described. Acanthocephalans invariably have giant nu- clei during their early developmental stages. In Palaeacanthocephala the giant nuclei fracture in later developmental stages and remain frag- mented in the adults. In Archiacanthocephala and Eoacanthocephala, they are variably re- tained in the adults. The persistence of giant nu- clei in adult Acanthocephala is inconceivably purposeless. The wide variety of shapes and ar- rangements assumed by giant nuclei, particularly those of the subcuticle in Eoacanthocephala, e.g., Neoechinorhynchidae, are evident in the taxo- nomic literature. This study was undertaken with the view that these nuclei must have some re-