hed DF bet Ay ny aac
bt
prey e Be ati ali
seaiagioaa i [os i S a re ieee
aera hte
(ey vi ia Hit
Rane ONO Aah tan
Pervanredia st WORE reo sheet tae
capa
Mata
else ih su anit siNiinayaijae ”
ih aa ang septa
Ian ta ioe
yy i
init
i L irr H had Pama ie Hit aa oP fete Phat ho ba iy J ves My 1 iM eben apat ae it ous Nite Pins tsYh aa iy 14 OV an et at ee PURE atnatatatsaaeatatsentea pdt synth ee Het i te epee ihe Neate eisai Watpaaisebdiocaoli ith Rie hat ae a as oHl hap ay Hate ber Gutta
94H on) p0n8 5
) int ate Seren Se i uae tstieorafeerrentrenns i ty hi et ait Witt sine ih iy Hy tae aetna eh
ata tte Ni teat)
WAL dh
Weide Ae Sul Mvarh alibi
ont tey aaa eee
nnn eee al ih oi i AN Mitte Spneent hay ase ashen , BOI Hat te since ‘| bit eat noc seerenieeatsaeFepeeaaaratih oe tes fiche OM ac Huai Aire a cl iat eoianes tan aN A we Mitesh jeunes att inh i iby Hesttrt vxit sin at nt eananien lesesete et
af) a etn ye Rafts ¢ nite be dP a ipapene Rint ear a Hane a taanineehd oS itp rap reign oi ia vei lr oe i inant aa sibs tenet ah an te ate nh aia 4 }1br bag east 9: eyenepnaie)) Ct
ay yas 8 Ai ai aon fate
aan
ct he
ia a ne NM it inate
tail Hint is i
ie ea ‘4 Hie i tak vt
PTA Wei ith
io a3 ahah ceo renee tents bag aga f ea lprteye haem ode R BLiAv bes ACANU Niet aah veut aig ie (iets jeaefunonge ipa te ned aa Rote Rs eh i See tT Ht thiidaipeteeb fear eee atte iby Fea hin mnidtaiil Lint) Hheitbonet iit He ne bit fin ie nineteen sii att ereremns YAR RTM ean iva Sey aea neonatal ' fragt Mite He isn na ait bay vase i tip i] ulna iH deen WeeHAt Hee eit f SACO ASIROAROK AMER HA AGE y viebeistepead ity et iri eh bisabetly tt basa ‘ett iin mth Ban
Rivet
ae soap aee
rene ee ln ane ee ae stasabareategetg ty Hpaliitierie see ter reapers rot 4 bate , rit tyre ytuath
a ign es i
Pbab dd Prilsbade bs Heaney aptiaen
cds ancy Leeaia lab yed dag dagtagan \ ihe
avnateut gegen Hat tertensernadl
PHiAetit bet Gilets
sa
(ats Eth ica tae a
eae f Beatie iets nebo eag enant at a eh ee ile
shee bake ithe Eien seein
otal estes st ai nity eae Heat } bei ett nt iy ii ss = ine ities Gettis iiveon yi un i ait if Neto RE fe Tet teh thn tedeette mi ile oe st eth eh ee it ase Piet on nlotaiteacentateat uy att eh) ‘i aap abst eit
vianareee
The iapnpeninat
nH ot en bien ie diya detel uci ee
tes bettowehog tute tt
prvertirines, ane ete
Tae aber ify hs ry Atty i oat
ies ie f Dan nt PUT os f f
tape ren tn ia ee
Matta aarp epee ah Hii iil Hie estan sites eaneneaeney H sin 4 et i} pijabeioaysysee ; ty iy Wie Se He Ak tiie as ait reget ii i gta mae reset tah tn ved bens eK os Higetts bite i HaHa oe Hedy melt Me st ‘s ity ae eit rT ae winnie ft abe give
site PAH ave
iia ae west
daederae see taba asic i ee 4 i
pail iter padeettt reneepeaersf
praia big
ait y peat iy iN] i ee i =
\ Nea Wri heat
iteeani'g lyin thon Wisden Wot mith
; Ryo i Jy
ae iattelt i it ay He uh caine Ait Dia EARN Hh
{ ales by i th MN tee ‘ 1 My Gest Te bi reerg tt Per ceerston paseianai es ii Bi eee
AMT
isn) stn Meant et
sa + 1H te Ra pep apsg rt ale a ate Bt 3 se a ace i IAD ett in ne yy auth ania ih Ne she ee Fea ean a aie ean i tan oro ARR Wehtacetaappetasae gs ee nu ica Pest rivaiha at ait mint aL AHHH aa ry tin my id sya iit rie iy ihari esd teanssdsdtiva aa tevisaHdeeaitUr eh Gates % ioe Wii ate i is ee i = (agate faa ce a H
Oh MA ANG eh sith tht
hs eee
ee Meh gaunt ean ih bit ie hae aa At ati 4 a7As ne
Se a a ioe
ae re ce bf Hh sit
ae te
Se o
i I i
iit wi +H ih riety f iat cae
cea teathoristastrs i tndakese vain stasis Psa neatnptisalest ibtayterne
ke aS
es a ee rate
pa Det Vee cbasgaue i wr at
wlan ! aN i iat oy eet nit Heath aeeal tv ia ttt iat
ty! Herb ren Hah vt int i ina a a pies o ae Bes cay prayers it oo mitiatebtet ete sirens pth
HL
Sea Ae
a dsaseith
gable i) Milli ina sania ae Ht be Ashe ae nila ade oo i ite set i
j pH rahe Bt) it 4 PE aK Wil 4 4 itihanintooe i si) Tene ydeutad velirivartlertaal {iy ee a ratty)
aS NOL san
i yt Hy eed helt thy ya
ee I ane ete ate ” a bri uy Sees eit 4
DORIC HTS) 149 bral by ta
Hentsds reetrery eat ap er ra oenbe Titetesstaeuranitgsn netaevetcorer tis rpeeeses
Stic = nannoneatia
sii ioe
9 eH
4 ul alas
Hermocved NTN ai ii VW Goma tbe
oe mH ae bdebbiae
aa ieee , : i i 0 ist ht ise me SSE areas in vibe shiv hall Wd» i it ee re eaareree ur beospre Seni) eset MP sn ‘ Fereue hub hiiieasguae el ahs denty: Hons Mis oa st Sennen v peruse ‘st cist Aeheh wraelssotaiosatn Haas theanelni a aTNattheaitey iiStaceaan in ‘ hoon tan } Ay ths ! Ht
A hei tid istatbnho! je ee at Re bat rere sab abeted tvnedd bathe r on
i ri oh
onan ete Tat Shei abe teraatacent het dite ieate pera
samen ienmenmrsteeat ROMANE ios MO lineal Sea vit viyaneara phic reteere ian nag Ly) Tesbevaiihactenty i i eae epetsaet eiahtpatt ent wa Viren Wb lad Len A} wh s iteavebeeresss SONG aster
ees ees ol Si7% on
Return this boox on or before the Latest Date stamped below. A charge is made on all overdue books.
University of Illinois Library
ILLINOIS BIOLOGICAL MONOGRAPHS
VoLuME XVII
PUBLISHED BY THE UNIVERSITY OF ILLINOIS
URBANA, ILLINOIS
EDITORIAL COMMITTEE
Joun THEoporE BUCHHOLZ Fred WILBUR TANNER HarLey JONES VAN CLEAVE
No
No
TABLE OF CONTENTS
. 1. Comparative Studies on Trematodes (Gyrodactyloidea) from the Gills of North American Fresh-water Fishes. By JouNn Dary MIZELLE.
. 2. The Microthyriaceae. By Frank LrINcoLn STEVENS and SISTER Mary Hixaire Ryan, O.P.
. 3. The Branchiobdellidae (Oligochaeta) of North American Cray- fishes. By CLARENCE JAMES GOODNIGHT.
. 4. Cytological Observations on Endamoeba blattae. By Pau A. MEGLITSCH.
Digitized by the Internet Archive in 2011 with funding from University of Illinois Urbana-Champaign
http:/Awww.archive.org/details/comparativestudi171 mize
ILLINOIS BIOLOGICAL MONOGRAPHS
VoL. XVII No. 1
PUBLISHED BY THE UNIVERSITY OF ILLINOIS UNDER THE AUSPICES OF THE GRADUATE SCHOOL Urpana, ILLINOIS
EDITORIAL COMMITTEE
JouHN THEODORE BUCHHOLZ FRED WILBUR TANNER Harvey JONES VAN CLEAVE
UNIVERSITY OF ILLINOIS
1000—9-38—13790
COMPARATIVE STUDIES ON TREMATODES (GYRODACTYLOIDEA)
FROM THE GILLS OF NORTH AMERICAN FRESH-WATER FISHES
WITH FIVE PLATES
BY
Joun Dary MIZELLE
CONTRIBUTION FROM THE ZOOLOGICAL LABORATORY OF THE UNIVERSITY OF ILLINOIS No. 520
THE UNIVERSITY OF ILLINOIS PRESS URBANA 1938
ACKNOWLEDGMENT
The author wishes to express his thanks and ap- preciation to Professor H. J. Van Cleave of the Department of Zoology, University of Illinois, for his encouragement and valuable suggestions; to Dr. D. H. Thompson and Mr. D. F. Hansen of the Illinois State Natural History Survey for their generous assistance and cooperation in the collection and identification of host species; to Drs. N. T. Mattox, W. C. Van Deventer, M. S. Ferguson, Mr. W. S. Summers, and the many other University of Illinois students of zoology who so willingly aided in the collection of host material; to his wife for assistance in the prepara- tion of the manuscript; to Dr. R. C. Hughes, of the Department of Zoology, Oklahoma Agricultural and Mechanical College, for reading the manuscript and suggesting many valuable corrections and additions; and to Dr. J. F. Mueller, of the New York State Col- lege of Forestry, for generous loan of type material.
. Superfamily Gyrodactyloidea Johnston and Tiegs, 1922
3
V OV,
CEN
CONTENTS
Introduction . Materials and Methods Order Monogenea Carus, 1863
Historical Review
Key to the Suborders of Monogenea Carus ion Key to the Superfamilies of Monopisthocotylea Odhner, 1912
General Morphology of the Gyrodactyloidea
Key to the Families of Gyrodactyloidea
The North American Fresh-Water Gyrodactyloidea
Review of Taxonomic Literature
Key to the Subfamilies of Gy <oAsseotiaen ¢ Cobbold, 1877 Key to the Subfamilies of Dactylogyridae Bychowsky, 1933 General Morphology of the North American Fresh-Water
Tetraonchinae Monticelli, 1903
Key to Genera of North American Fresh-Water Tetraonchinae
Genus Cleidodiscus Mueller, 1934
Diagnosis .
Cleidodiscus robustus Mueller, 1934 Cleidodiscus capax Mizelle, 1936 Cleidodiscus longus Mizelle, 1936 Cleidodiscus uniformis Mizelle, 1936 Cleitdodiscus vancleavet Mizelle, 1936 Cleidodiscus bedardi Mizelle, 1936 .
Cleidodiscus diversus sp. nov. Genus Onchocleidus Mueller, 1936
Diagnosis
Onchocleidus pinokpalke: Mizelle, 1936 Onchocleidus interruptus Mizelle, 1936 Onchocleidus mucronatus Mizelle, 1936
Onchocleidus distinctus Mizelle, 1936
Onchocleidus cyanellus sp. nov.
6 ILLINOIS BIOLOGICAL MONOGRAPHS
Genus Actinocleidus Mueller, 1937 . Diagnosis oe Pa Actinocleidus articularis (Mizelle, ie Actinocleidus longus sp. nov. Actinocleidus fergusoni sp. nov.
Genus Pterocleidus Mueller, 1937 Diagnosis ane oi, ces Pterocleidus acuminatus (Mizelle, 1936)
Genus Urocleidus Mueller, 1934 Diagnosis Urocleidus umbraensis sp. nov.
Genus Dactylogyrus Diesing, 1850 Diagnosis Dactylogyrus bychowskyi Mizelle, 1937 Dactylogyrus bifurcatus Mizelle, 1937 . Dactylogyrus simplex Mizelle, 1937 Dactylogyrus atromaculatus sp. nov.
Economic Importance Discussion
Summary . Bibliography .
Plates .
INTRODUCTION
This investigation was begun originally in the fall of 1933 as a general survey of the parasites of the Centrarchidae of Champaign County, Dli- nois. After two years of collecting, an attempt was made to identify the monogenetic trematodes, all of which had been preserved in Bouin's solution, before proceeding with the work on the other helminth parasites collected. Due to coagulation of adherent mucus and subsequent ad- hesion of specimens to the inner surfaces of vials, no Gyrodactyloidea were found in the fluid poured from containers in which specimens had originally been placed. New material was collected and the identification of parasites from living and freshly prepared mounts was undertaken together with the problem of perfecting a suitable technique requisite for research on this group of trematodes. As the work progressed the Monogenea were found to offer such a fertile field for investigation that on March 1, 1936, the problem was restricted to monogenetic forms only and expanded to include hosts of the piscine families Centrarchidae, Ser- ranidae, Cyprinidae, and Poeciliidae from various localities throughout the State of Illinois without restriction to any particular county. A few distribution records from Oklahoma have been made and included in this presentation.
Some of the research covered by this monograph has been briefly presented in three previous papers (Mizelle 1936, 1937, and 1938).
MATERIALS AND METHODS
Due to a lack of time for examination of a large number of fishes collected from several localities on the same date, freezing was resorted to as a means of host preservation. On examination of the branchial material so treated, many of the monogenetic forms present were found free from the host tissues in the containers used for examination. Further work on the efficacy of freezing as a method for the removal of ectopara- sitic trematodes from gill tissue resulted in the discovery of an optimum time of exposure ranging anywhere from six to seventy-two hours. In addition to the removal action, freezing also has the simultaneous effects of killing the parasites in a relaxed condition and of breaking up the mucus, both of which facilitate examination and preservation. Exposure for a shorter period than the above-stated minimum fails to break up the mucus to an optimum degree, while over-exposure distorts the specimens.
8 ILLINOIS BIOLOGICAL MONOGRAPHS
After freezing, the fishes were thawed in tap water, the gills removed, placed in stoppered homeopathic vials about two-thirds full of tap water, and vigorously shaken between thumb and forefinger for approximately fifty consecutive times. The liquid containing the parasites was then poured into Syracuse watch glasses and alternately diluted and decanted until clear enough for reliable examination with a widefield binocular microscope. The parasites were collected with a capillary pipette equipped with a rubber bulb and transferred to clear water to insure further re- moval of mucus. Experiments with fifty sets of gills taken from four species of sunfishes, namely, Helioperca macrochira (Rafinesque), Allotis humilis (Girard), Xenotis megalotis (Rafinesque), and Apomotis cyan- ellus (Rafinesque), have shown this method to be effective in removing ninety-two per cent of the gill trematodes present.
For making permanent mounts, the specimens were transferred from watch glasses to slides coated with Mayer’s albumen. These were placed on inverted stender dishes in a finger bowl. Alcohol was poured into the container to a level below the top of the stender dishes, the top of the bowl was covered, and the apparatus set in an incubator. It was found that exposure for a period of from one to five minutes (depending upon the amount of water transferred with the parasite to the slide) at a temperature of about fifty-five degrees centigrade was sufficient to coagu- late the albumen and securely attach the specimens to the surfaces of the slides. After attachment, the specimens were fixed in either Gilson’s or Bouin’s fluid and treated subsequently for removal of mercuric salts or picric acid. Specimens were stained in either Ehrlich’s acid haemotoxy- lin, borax carmine, or a mixture of Ehrlich’s acid haemotoxylin and Delafield’s haemotoxylin in a saturated aqueous solution of potassium alum. It was later discovered that Mayer’s albumen was unnecessary and that removal by pipette of the major portion of glycerine and water in which a parasite had been placed on a slide, caused adherence of speci- mens to the glass surface. Additional adherence was secured by im- mersing the preparations in fixatives (Gilson’s or Bouin’s) contained in Coplin jars. Inconsistencies in staining together with poor differentia- tion and obscuring of structures possessing critical taxonomic value, viz., anchors, bars, hooks, and copulatory apparatus, caused the final abandon- ment of staining procedures ( Mizelle, 1937). Thereafter the specimens were mounted, unstained in balsam. Because of small size and the tendency of the anchors to become entangled in debris and in the cuticula of other specimens, it was found practically impossible to handle these parasites in containers during the ordinary technical processes requisite for mounting. Either of the above procedures for fixation of speci-
STUDIES ON TREMATODES—MIZELLE 9
mens to slides works very well, but the latter is preferred by the present author because of a shortening of the time element.
The term haptor for attachment organs as proposed by Price (1934a) is adopted. The following terms are used as proposed by Mueller (1936) : anchors for the large hooks of the haptor; wings for the membranous structures arising from the convex surfaces of the anchor shafts; bars for the chitinous structures connecting the bases of a pair of anchors; and hooks for the smaller marginal armature of the haptor. The term copulatory complex is used for the ensemble of the male copulatory struc- tures such as the cirrus, accessory piece, cirral thread, and cirral fin when present in combinations of two or more. Buccal canal is proposed for the anterior portion of the digestive tube between the pharynx and the opening to the outside.
In forms with nonarticulate bars, the anchor pairs are designated dorsal and ventral, since their shafts curve toward and their points project from the dorsal and ventral haptoral surfaces. In forms with the bars articulate with each other, both pairs of anchors lie on the ventral side of the haptor, and while the designation of the roots is the same, the respective anchors and bars are designated anterior and posterior instead of ventral and dorsal. For ease of reference the two roots comprising the bases of the anchors are designated with regard to the surfaces of the haptor. The root nearest the surface is thus designated the superficial root and the other the deep root. Mueller (1936) designated the roots of the anchor bases with reference to the anchor points and classified them as internal and external. In his system the inner and outer roots corre- spond respectively to the roots designated as superficial and deep by the present writer.
The haptoral hooks are numbered consecutively from ventral to dorsal surfaces beginning near the anterior central portion of the haptor and proceeding posteriorly on the ventral side and then anteriorly on the dorsal surface (see figs. 173-174). The two pairs of hooks on the dorsal surface are numbered six and seven, number six being the more posterior. The hooks of pair number five are usually situated nearer the ventral than the dorsal surface. They may lie between the bars or between the distal ends of the ventral anchor shafts.
Descriptions of forms in this work have been made on living speci- mens as well as on stained and unstained mounts. Sections were made of Cleidodiscus robustus Mueller, 1934, and Cleidodiscus capax Mizelle, 1936. Measurements do not follow surfaces of curved structures, but have been made across the arcs formed by them. For example, an anchor length consists of a measurement extending from the region of junction
10 ILLINOIS BIOLOGICAL MONOGRAPHS
(curved portion) of the shaft and point to the tip of the more distant root of the anchor base.
All measurements, except those of the anchors, hooks, bars, and cirri were taken on freshly killed specimens temporarily mounted in a solution of equal parts of glycerine and water, on glass slides without cover- glasses. Measurements of the anchors, hooks, bars, and cirri were made with coverglasses on the preparations. Each mean measurement given in this work is a calculated average derived from measurements taken from twenty different specimens.
After considerable research on this group of parasites (Tetraonchinae and Dactylogyrinae) a modification of the relative importance and treat- ment of different structures was made with reference to their taxonomic value. In the first part of the work the haptoral hooks were measured individually, but no figures of these structures were given. In later parts of the investigation the hook measurements are usually represented by minima and maxima for the total number of hooks present, and descrip- tions for these are supplemented (except Actinocleidus fergusoni n. sp.) by one or more figures to illustrate the extent of differentiation of parts. In similar manner the cirrus descriptions have been supplemented by measurements which were omitted in the earlier portion of the investiga- tion. It should be pointed out that species described herein are arranged according to genera and not with reference to chronological completion of descriptions. Since the general internal structure in the subfamilies Tetraonchinae and Dactylogyrinae is very similar, figures of whole specimens are not given for all the species described. Structures con- sidered to possess critical taxonomic value are figured for all the forms described in this work.
Type material (cotypes) of forms described herein have been de- posited in the U. S. National Museum Helminthological Collection.
ORDER MONOGENEA CARUS, 1863
HistorrcaAL REVIEW
The group Trematoda, named by Rudolphi in 1808, as an order, origi- nally included the following genera: Monostomata Zeder, Amphistomata Rudolphi, Distoma Retzius, and Polystoma Zeder. In 1858, van Beneden proposed the term monogénéses for trematodes which develop without metamorphosis and digénéses for those which develop with metamor- phosis, the former category generally consisting of ectoparasites and the latter exclusively of endoparasites. In 1863, Carus proposed the terms Monogenea and Digenea, respectively, to replace the two terms of van
STUDIES ON TREMATODES—MIZELLE 11
Beneden. In 1892, Monticelli divided the order Trematoda into the sub- orders Heterocotylea, Aspidocotylea, and Malacocotylea. The suborder Heterocotylea coincides with the Monogenea (Pratt, 1900). The Aspid- ocotylea and Malacocotylea are divisions of the Digenea. Odhner (1912) divided the Monogenea of Carus into the Polyopisthocotylea and Mono- pisthocotylea, respectively, on the basis of the presence or absence of a genito-intestinal canal.
According to Fuhrmann (1928), as set forth in Kukenthal’s Handbuch der Zoologie, the Monogenea and Digenea of Carus are accepted as orders and the order Trematoda Rudolphi, is elevated to the status of class. The order Monogenea Carus, as given by Fuhrmann, embraces three sub- orders, Monopisthodiscinea, Monopisthocotylinea, and Polyopisthocoty- linea. The suborder Monopisthodiscinea is divided into four families, Protogyrodactylidae Johnston and Tiegs, 1922, Gyrodactylidae Cobbold, 1877, Dactylogyridae Bychowsky, 1933, and Calceostomatidae (Parona and Perugia, 1890). The suborder Monopisthocotylinea contains three families, Udonellidae Taschenberg, 1879, Monocotylidae Taschenberg, 1879, and Tristomidae van Beneden, 1858, while the suborder Polyo- pisthocotylinea is divided into five families, namely, Polystomidae van Beneden, 1858, Microcotylidae Taschenberg, 1879, Octocotylidae van Beneden and Hesse, 1863, Onchocotylidae Cerfontaine, 1899, and Diclidiphoridae Cerfontaine, 1894.
Price (1937a) prefers the divisions Monopisthocotylea ( — Mono- pisthodiscinea and Monopisthocotylinea) and Polvopisthocotylea (— Poly- opisthocotylinea) of Odhner to those of Fuhrmann and designates the superfamilies Gyrodactyloidea Johnston and Tiegs, 1922, and Capsaloidea Price, 1937, respectively, to replace the suborders Monopisthodiscinea and Monopisthocotylinea of Fuhrmann. Price’s classification is followed in the present publication.
KEY TO THE SUBORDERS OF MONOGENEA CARUS
Genito-intestinal canal wanting; haptor with or without a large sucking disc.. Pp Re ee ovrare Ste See oie ahaa eror ciate leronst ears, whave eis. 4 Cayetercael eters tye Monopisthocotylea Odhner
KEY TO THE SUPERFAMILIES OF MONOPISTHOCOTYLEA ODHNER, 1912
Posterior haptor armed; anchors with supporting bars..................---- FE On CCT arene rire Gyrodactyloidea Johnston and Tiegs Posterior haptor armed or unarmed; when armed, anchors without supporting DAT Sree errs Sere ere ie wine cw Oe bok ea ha enone Sa Meee nee Capsaloidea Price
12 ILLINOIS BIOLOGICAL MONOGRAPHS
SUPERFAMILY GYRODACTYLOIDEA JOHNSTON AND TIEGS, 1922
GENERAL MORPHOLOGY OF THE GYRODACTYLOIDEA
Changes in classification, since the characterization of this super- family by the above authors, have made it necessary to revise parts of their description. The description of the reproductive system, however, is taken from their monograph.
General anatomy.—The superfamily Gyrodactyloidea contains forms found in or on fishes, amphibians, and cephalopods. The species are characterized by the absence of anterior haptors and suckers of the ordi- nary type. A posterior haptor is present and consists of an armed disc which may or may not be distinctly set off from the body of the parasite. The haptor possesses hooks only (Isancistrinae), or hooks and anchors (one or two pairs) whose bases are connected by chitinous bars. The relationships of elements of haptoral armature vary greatly in different groups. Eye spots may be present or absent. In the pharyngeal region there are masses of glandular tissue which open to the outside by structures called head organs by Johnston and Tiegs (1922). An excep- tion to this condition occurs in the family Calceostomatidae, in which these glands open by small ducts not concentrated in groups to form the so-called head organs.
Reproductive system.—‘The testis is a compact or only slightly lobed organ, single or double, and never lies anterior to the ovary. The vas deferens may be a simple tube hardly expanded into a vesicula seminalis, or it may be widely dilated; sometimes enormously so in the Australian species. A bulbous ejaculatorius may or may not be present. The cirrus may range from a simple chitinous tube to a structure of considerable complexity, while an accessory clasping apparatus may occur.
“The ovary may be a branched or unbranched organ, lying either in the midline or asymmetrically. A vagina may be present (single or double) or absent; and there may be a receptaculum seminis connected with it.
“Shell-glands may vary from simple glandular thickenings of the ootype, to very prominent glands connected by long ducts with the female duct. The female aperture usually lies immediately behind the male opening, but sometimes at a considerable distance from it, generally later- ally. Never more than one egg is present in the uterus. The egg may be laid, or it may be retained in the uterus to develop into a young worm which may, while im utero, produce a second generation.
STUDIES ON TREMATODES—MIZELLE 13
“The yolk system may be poorly or strongly developed. In the most primitive members of the group there is a very distinct communication between the yolk system and the intestine in the posterior region of the animal.”
Digestive and excretory systems.—The mouth opens into a short buccal canal which empties into a muscular pharynx. An esophagus may or may not be present. The intestine may be saccate or bifurcate to form two crura which may or may not possess caeca. The crura may end blindly or be confluent with each other in the posterior body regions.
Johnston and Tiegs (1922) state, ‘““Excretory ducts open either at the anterior end or, in some forms, probably at the posterior end.’’ In the Dactylogyrinae and Tetraonchinae the present author is sure of ex- cretory openings only in the anterior regions at about the level of the copulatory complex (see page 17).
‘
KEY TO THE FAMILIES OF GYRODACTYLOIDEA
TEMA TV ID ATOUS) saierersna ts ase ee sesetts acaitse aes ee area ie MS AOS es Gyrodactylidae Cobbold Ovi par Ouse sac deeiac tcerescieveeneedsanivendusiecbsvanevaqesacdierbibielagscvare aialesote ddneleccl a.5.0uh%% aegagp se. accha woe 2 2. Vitello-intestinal duct present......... Protogyrodactylidae Johnston and Tiegs Witello-intestinal duct wanting) 6s: co<eansactae ear adigeleadovderaue nanos cen 5
3. Anterior end of body expanded to form head lappets....................- ieneperelsiahets ec leusis take Bierce he caer Calceostomatidae (Parona and Perugia)
Anterior end of body not expanded to form head lappets................. BP ey ae eel he rok a eicisnc ore PBe” whic. ccs verte merevie Sic aeest Dactylogyridae Bychowsky
THE NORTH AMERICAN FRESH-WATER GYRODACTYLOIDEA
Review oF Taxonomic LITERATURE
Specific taxonomic investigations concerning the Gyrodactyloidea from North American fresh-water fishes have been meager.*’ Most important _ are the works of Mueller (1934, 1936, 1936a, 1937, 1937a, 1938), Mueller
and Van Cleave (1932), Van Cleave (1921), Van Cleave and Mueller (1932 and 1934), and Price (1937a). In 1934 Mueller created the genera Cleidodiscus and Urocleidus; in 1936 he created the genera Onchocleidus, Leptocleidus, Tetracleidus, and Aristocleidus; and in 1937 he created the additional genera Hapflocleidus, Pterocleidus, and Actinocleidus. The established genus Ancyrocephalus was made to include strictly marine forms (Mueller, 1936) and certain fresh-water Tetraonchinae of un- certain generic relationships.
1The major portion of the work on the American fresh-water Gyrodactyloidea has dealt
with control measures and identification only to genus. A literature review of this work will be found in the section of this publication dealing with economic importance.
14 ILLINOIS BIOLOGICAL MONOGRAPHS
The present author ( Mizelle, 1936) described twelve species of Tetra- onchinae from the gills of Illinois Centrarchidae and Serranidae. In 1937 he described three species of Dactylogyrinae from the blunt-nosed min- now, Hyborhynchus notatus, and at present has descriptions of four ad- ditional species of Tetraonchinae and one species of Dactylogyrinae in press. Another species of Tetraonchinae (Actinocleidus fergusoni) is originally described herein. The six last mentioned forms will be listed as new species in this publication. Including all the forms in the above taxonomic categories, the described species of North American fresh- water Gyrodactyloidea now total sixty-one. Three of these, namely, Tetra- onchus monenteron (Wagener, 1857), Dactylogyrus anchoratus (Dujardin, 1845), and Gyrodactylus elegans von Nordmann, 1832, were first described from another continent (Europe). Seven of these belong to the Gyrodactylinae (genus Gyrodactylus), six to the Dactylogyrinae (genus Dactylogyrus), forty-seven to the Tetraonchinae, (12 Cleidodiscus, 11 On- chocleidus, 9 Actinocleidus, 3 Haplocleidus, 3 Pterocleidus, 3 Urocleidus, 2 Tetraonchus, 1 Leptocleidus, 1 Aristocleidus, 1 Tetracleidus, and 1 Ancyrocephalus), and one to the subfamily Lepidotreminae, viz., Le- pidotes collinsi Mueller, 1936.
Price (1937a) lists forty-five Dactylogyrinae and nine Gyrodacty- linae as foreign species (mostly European). Mueller (1936) gives six as the number of European species of fresh-water Tetraonchinae. According to the above information, the species of Gyrodactylinae are about evenly distributed between North America and Europe, whereas most of the Dactylogyrinae are found in Europe and most of the Tetraonchinae in North America.?
KEY TO THE SUBFAMILIES OF GYRODACTYLIDAE COBBOLD, 1877
Haptor with two anchors and 16 hooks................. Gyrodactylinae Monticelli Haptor without anchors but with 15 hooks................ Isancistrinae Fuhrmann
KEY TO THE SUBFAMILIES OF DACTYLOGYRIDAE BYCHOWSKY, 1933
l.. Haptor with. 2 pairs: of anchors! :i: joc cc aalee..c is acad reg toaiate se ersicngvaue lee alee. sietaicmats 2 Haptor with 1 pair of anchors... ss.s0%se cee Ged ios oobsc6 Kae scene eae oness ee 3 2. Haptor with a pair (dorsal and ventral) of accessory structures or squamodiscs ese mics avis SEa MIR Sea eacastaRev aha in Pisce knee eos She ener ee mere Diplectaninae Monticelli Haptor without squamodiscs.............00+eee eee eee Tetraonchinae Monticelli
3. Haptor with a circle of heavy cuticularized, tubular structures............ nop ed aesnan Seana ite Bere ee grene a Show ouaty eneee. csvOuta sseuevaueseidiarsverete Bothitrematinae Price
1After this publication went to press Mueller (1938) described additional species of Tetra- onchinae and Dactylogyrinae.
STUDIES ON TREMATODES—MIZELLE 15
GENERAL MorpPHOLOGY OF THE NortH AMERICAN FRESH-WATER TETRAONCHINAE Monrvice-tt, 1903
General anatomy.—The flattened body comprises two distinctly tandem regions, an anterior, very narrowly elliptical, body proper and a posterior, hexagonal or discoidal haptor.t The body surface is devoid of scales (except in some specimens of Cleidodiscus robustus Mueller, 1934). Internal monaxon spicules are very infrequently found in the body parenchyma, namely, in some specimens of Cletdodiscus robustus and Cleidodiscus capax Mizelle, 1936. A pair of lateral lobe-like projections (cephalic lobes) are generally present in the head region. Two pairs of eye spots are present, located dorsally near the anterior end, with one pair behind the other, those of the anterior pair being generally smaller. Each eye spot is composed of an aggregation of melanistic granules which are easily separated from each other by cover-glass pressure. A group of glandular cells occurs on each side of the body in the region of the pharynx. These glands open to the exterior by head organs situated on the anterolateral margins of the cephalic region.
Four anchors always present on the haptor, generally similar in shape (except genus Aristocleidus Mueller, 1936) and size (except genus Haplocleidus Mueller, 1937). Each anchor is differentiated into a base, which is usually bifurcate to form two roots; a shaft which may be solid or hollow; and a point which projects from the surface of the haptor. The shaft may be regularly recurved distally, merging imperceptibly with the point or sharply recurved to form a distinct internal angle at this locus. Membranous wings, so designated by Mueller (1936), arise from the convex surfaces of the anchor shafts. These have been found uni- versally present in the species described in this investigation. However, these structures exhibit differential development and are often scarcely perceptible in some species. Two bars always present (except in the genera Tetraonchus and Murraytrema), each of which connects the bases of a pair of anchors. The bars generally exist as separate structures. Actinocleidus Mueller, 1937, is the only genus in which the bars are articulated with each other. Seven pairs of chitinous hooks (eight pairs in Tetraonchus) are generally present on the haptor. A hook may be a solid or a hollow, cylindrical, tapering rod ending distally in a sickle- shaped process and opposable piece, or a solid structure distinctly differ- entiated into a base, shaft, sickle-shaped termination and an opposable
piece. Five pairs of hooks are located ventrally and two pairs dorsally (see figs. 173-174).
1Due to contraction at death, the postero-lateral sides of a haptor, normally hexagonal, may be pulled together to the extent that the posterior side is obliterated and in such case the structure assumes a pentagonal shape. The junction of the haptor with the body is con- sidered one side of the haptor. Body contraction at death may shorten or accentuate the peduncle so that relative separation of haptor from the body becomes a poor descriptive character.
16 ILLINOIS BIOLOGICAL MONOGRAPHS
Reproductive system.—The single testis, regular in outline, is located in the posterior half of the body and may be dorsal, posterior, or postero- dorsal to the ovary. The vas deferens passes forward, generally, on the left side of the body, and usually dilates to form a seminal vesicle im- mediately posterior to the cirrus base. Two prostate glands generally present, situated near the posterior end of the copulatory complex, and each connected with the cirrus by a single individual duct. The prostate glands are similar to those described by Goto (1894) for the genus Epibdella. The copulatory complex consists of a cirrus and one or more of the following chitinous structures: solid accessory piece, cirral thread, and cirral fin. This compound structure is situated in a vestibule imme- diately in rear of the esophageal bifurcation. The cirrus projects or empties ventrally through the vestibular pore.
The ovary is a nonlobed organ with spatial relationships with the testis as given above. It may be larger or smaller than or about the same size as the testis. Internally it is filled with relatively large, clear, nucleated eggs of different sizes, which are easily visible in living mounts. The eggs diminish in size toward the posterior portion of the ovary. The oviduct arises from the anterior portion of the ovary and passes forward near the midline of the body. Never more than one egg has been observed in the oviduct at a given time. The egg pore is situated ventrally near the vestibular pore. The single vagina (wanting in the genus Urocleidus and also in species of other genera) may occur on either lateral body margin. It is generally provided with a chitinous tube which connects it | with a seminal receptacle, situated near the anterior end of the ovary. The vitellaria consist of innumerable minute follicles arranged in two lateral longitudinal bands extending from dorsal to ventral body surfaces. Anteriorly these bands may or may not be confluent immediately behind the pharynx near their anterior limits but are always broadly confluent posteriorly on or near the peduncle. Encroachment of the vitellaria on the midbody regions of old individuals may become so marked as to obscure the visibility of internal organs. Vitelline ducts enter the odtype one on each side just anterior to the ovary as described by Goto (1894) for the genus Tristomum Cuvier, 1817, and by MacCallum (1915) for Ancyrocephalus teuthis.
Digestive and excretory systems.—The mouth is located in the mid- ventral region near the level of the anterior eye spots. A short buccal canal passes posterodorsad to enter the well-developed pharynx. The short esophagus bifurcates (except in Tetraonchus) to form two lateral intestinal crura which unite posteriorly (except in Murraytrema) in the region of confluency of the vitellarial bands.
The excretory system consists of a maze of ramifying tubules pre-
STUDIES ON TREMATODES—MIZELLE 17
sumably terminating in flame cells. Basically a single pair of lateral collecting ducts (one on each side) occurs in the posterior part of the anterior body half. Anteriorly each tube bifurcates to form two ducts. One of these passes laterally at an angle of about forty-five degrees and empties on the dorsolateral body surface, near the level of the copulatory complex. The other passes anteriorly and terminates lateral to the anterior eye spot.’ Posteriorly the single duct referred to above bifurcates in the region of the ovary to form two tubes which pass pos- teriorly, turn mesiad in the region of confluency of the vitellarial bands and unite to form a short tube. This structure unites with its bilateral mate to form a single duct which terminates near or on the peduncle. Especially large solenocytes have been observed in some species between the level of the ovary and the base of the copulatory complex. Flame cell numbers and patterns have not been worked out for the group. Note.—The status of most of the following genera is uncertain at the present time. The genera Onchocleidus, Tetracleidus, Aristocleidus, Haplocleidus, Pterocleidus, and Urocleidus are probably synonymous.
KEY TO THE GENERA OF NORTH AMERICAN FRESH-WATER TETRAONCHINAE (Excluding Tetraonchus and Murraytrema)
leenGirrus relatively simples, 26 cick cen Seer os oinremie es Shade esa eet eeteks obese 2 Cinniis?invaclarce: coil’ sec cars iee cae.cisisues odchardihesremts oar hies Leptocleidus Mueller Ze OUCHOTS Similar i SHAME. <5 «fcc, cicvacs 3 oars Sink tos vo oedecerdarish dee Mba Sar enchsbed dae aceataie 3 Anchors dissimilar in shape...............cceceeeeeeee eed Aristocleidus Mueller Se CANCHORS SIMilare dM: ‘SIZE. i524, out sans ened care 6 a wena Gs es ren AS See HENAN Pe gaa 4 Anchors markedly dissimilar in size...................5- Haplocleidus Mueller Hie Barsenonarticulates ccc fcicas ooxeasien oot talons again dk Savaae ee aaa bateeedes weaned Bars articulate with each other...................0000- 007 A4ctinocleidus Mueller DeeM Via Cilla PrESEMt care rasc acs « ab cutee a: bes Sai-ada Wa EA Fu deck doe wIawes| deed ae 6 VAGINA WANING seca lice cess eee nse heeds So oaeaeaerag bode HS Urecleidus Mueller Gees Varinarson right body margin... .<.Gsseccew ence ovat ees os ch clean seat dees 7 Vagina on lett body margin. :..s0cc..0 0006 Seat eeacean Cleiaodiscus Mueller 7s Anchor Shatts: “without: Spurs s.0.20 seme as See eae Lisson on Nene videne cane ae 8 Anchor shafts: with SpurS<%s: sce % sense eaeaweleewes onsen Pterocleidus Mueller &. Accessory pieCe Presents... sccccsasinceamncele eneGanennens Tetracleidus Mueller AGCESSOrY “plECe, Wanting. .ociscsa cules ssc sa nae nea neend ane Onchocleidus Mueller
1The present author (Mizelle, 1936) observed what he interpreted to be excretory pores in the anterior and posterior regions of these parasites as mentioned by Johnston and Tiegs (1922). Further observations have failed to reveal these structures consistently, so that it seems best to avoid any detailed discussion of them at the present time.
18 ILLINOIS BIOLOGICAL MONOGRAPHS
Genus Cleidodiscus Mueller, 1934
Diagnosis —Tetraonchinae with intestine bifurcate but confluent posteriorly. Vagina present on the left body margin about midway the length. Copulatory complex consisting of a cirrus and accessory piece. Accessory piece well developed, always present and articulated to the cirrus base. Haptor distinct, discoidal, pentagonal, or hexagonal in shape. Two separate bars present, each of which connects the bases of members of a pair of anchors. Each of the fourteen hooks present is structurally differentiated into a base, shaft, sickle-shaped termination, and opposable piece. Parasitic on the gills of fresh-water fishes. Type species, Cleidodiscus robustus Mueller, 1934.
Cleidodiscus robustus Mueller, 1934 Figs. 1, 13-21 Hosts and Localities: Bluegill Sunfish (Helioperca macrochira), Illinois River,
Havana, Ill.; Chautauqua Lake, Havana, Ill.; Horseshoe Lake, Cairo, IIL;
Lake Decatur, Decatur, Ill.; Lake Senachwine, Henry, Ill—Green Sunfish
(Apomotis cyanellus), Embarrass River, Urbana, IIL.
Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9090.* Synonym: Cleidodiscus incisor Mizelle, 1936.
General anatomy.—Relatively large parasites whose surfaces often possess chitinoid scale-like structures. The parenchyma of old individuals very frequently contains monaxon spicules. Average length 1.414 mm. (0.615-2.296 mm.), average width at level of cephalic lobes 0.132 mm. (0.106-0.246 mm.), average greatest body width 0.216 mm. (0.121-0.410 mm.), average width of peduncle at junction with haptor 0.060 mm. (0.041-0.106 mm.). Haptor distinct, discoidal, and broader than long, average width 0.111 mm. (0.092-0.148 mm.), average length 0.106 mm. (0.082-0.139 mm.). Ventral bar similar in shape to dorsal bar but slightly longer. Average length of ventral bar 0.028 mm. (0.025-0.032 mm.), average length of dorsal bar 0.027 mm. (0.024-0.029 mm.). Anchors similar in shape, bases bifurcate, superficial roots about same length as knob-like deep roots. Wings present on anchor shafts but often so delicate as to be scarcely perceptible. Shafts of both pairs of anchors hollow and regularly recurved, making junction with the points without formation of an angle. Ventral anchors slightly longer than dorsal anchors, bases of the two pairs of anchors approximately the same width. Average length of ventral anchors 0.026 mm. (0.021-0.030 mm.), average width 0.012 mm. (0.010-0.017 mm.), average length of dorsal anchors 0.024 mm. (0.019-0.027 mm.), average width of dorsal anchors
r 1These specimens were deposited as cotypes of C. incisor, which is now a synonym of . robustus.
STUDIES ON TREMATODES—MIZELLE 19
0.012 mm. (0.009-0.017 mm.). Hook bases ovate and very short as com- pared with lengths of shafts. Hooks of pair number one slightly shorter than rest of hooks. The arrangement of the hooks is characteristic of North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm, Range in man. 1 0.015 0.013-0.017 2 0.017 0.015-0.020 3 0.019 0.016-0.023 4 0.019 0.017-0.023 5 0.016 0.014-0.017 6 0.019 0.017-0.021 7, 0.019 0.017-0.023
Anterior eye spots smaller and usually closer together than the members of the posterior pair.
Reproductive system.—Gonads near middle of body, testis ovate and located posterior to ovary. Vas deferns passes forward on leit side of body and expands to form a conspicuous seminal vesicle just posterior to cirrus base. Only one prostate gland has been observed. It is bulb- shaped, located posterior to the cirrus base and contains a coarsely granular yellowish fluid. It empties into cirrus base by a single duct arising from the anterior end. Copulatory complex well developed and situated in a relatively large vestibule. Cirrus a simple, curved, chitinous tube; accessory piece a blade-like chitinous structure with a knob near the middle, which serves as a site for attachment of muscles. Contractile elements arise on posterior surface of knob of accessory piece and insert on base of cirrus. On contraction of these structures the cirrus and accessory piece separate distally and the cirrus is projected ventrally, for a short distance, through the pore of the vestibule. Retraction mechanism of the cirrus not understood.
Ovary ovate in shape, smaller than testis, and situated anterior to it. Egg pore located on ventral surface on right of copulatory complex. Vagina present on left side, near junction of first and second thirds of body length; vaginal canal short, with a row of spines encircling the base at its junction with the large pyriform seminal receptacle. Vitellaria and vitelline ducts as described in the general morphology of North American fresh-water Tetraonchinae. Shell gland a cluster of glandular cells surrounding the odtype.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American Fresh-water Tetraonchinae. Average diameter of pharynx 0.076 mm. (0.046- 0.123 mm.).
20 ILLINOIS BIOLOGICAL MONOGRAPHS
Systematic position—In the present investigation this parasite has been taken only from the bluegill and green sunfishes. It occurs in mixed infestations on the former host with Pterocleidus acer (Mueller, 1936), Haplocleidus dispar (Mueller, 1936), Actinocleidus fergusoni n. sp., and Onchocleidus mucronatus Mizelle, 1936, and in mixed infesta- tions on the latter host with Cleidodiscus diversus n. sp., Actinocleidus longus n. sp., Onchocleidus cyanellus n. sp., and an undescribed member of the genus Actinocleidus Mueller, 1937. This form was described by the present author (Mizelle, 1936) as Cleidodiscus incisor. Study of Muel- ler’s type specimens revealed it to be a synonym of Cleidodiscus robustus.
One hundred per cent infestation with C. robustus was recorded for: nineteen bluegill sunfish from Chautauqua Lake, Havana, IIl., in May, 1936; thirty-one bluegills from the Illinois River, Havana, IIl., in May, and June, 1936; six bluegills from Horseshoe Lake, Cairo, Ill, in June, 1936; twenty-three bluegill sunfish from Lake Decatur, Decatur, IIL, in June, July, and August, 1936. Fourteen bluegills from Lake Senachwine, Henry, Ill., were found only fifty per cent infested with this gill parasite in June, 1936. The green sunfish is only occasionally infested with this helminth.
Cleidodiscus capax Mizelle, 1936 Figs. 7, 67-75 Hosts and Localities: White Crappie (Pomoxis annularis), Lake Decatur, Decatur, Ill.; Illinois River, Havana, Hl—Black Crappie (Pomoxis sparoides), Lake Senachwine, Henry, Ill.; Illinois River, Havana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No, 9079.
General anatomy.—Relatively large gill parasites devoid of surface scales but often possessing internal monaxon spicules in the parenchyma. Average length 1.603 mm. (0.959-2.050 mm.), average width at level of cephalic lobes 0.161 mm. (0.115-0.205 mm.), greatest body width average 0.301 mm. (0.180-0.410 mm.), average width of peduncle at junction with haptor 0.096 mm. (0.082-0.107 mm.). Haptor distinct, discoidal in outline and broader than long, average width 0.158 mm. (0.115-0.180 mm.), average length 0.106 mm. (0.090-0.123 mm.). Ventral bar heavier and slightly longer than dorsal bar. Average length of ventral bar 0.032 mm. (0.028-0.034 mm.), average length of dorsal bar 0.030 mm. (0.024-0.036 mm.). Anchors similar in shape, bases often nonbifurcate, obscuring the two roots which are always evident in young individuals. Wings of anchor shafts often so delicate as to be scarcely perceptible. Shafts of both pairs of anchors solid and regularly recurved without formation of an angle at the point of junction with their respective points. Ventral anchors larger than dorsal anchors, bases of ventral anchors markedly wider than bases of dorsal anchors. Average length of ventral anchors 0.032 mm. (0.026- 0.038 mm.), average width 0.027 mm. (0.019-0.036 mm.), average length
STUDIES ON TREMATODES—MIZELLE 21
of dorsal anchors 0.031 mm. (0.026-0.038 mm.), average width 0.023 mm. (0.019-0.029 mm.). Hook bases ovate and very short as compared with lengths of shafts. Hooks of pair number one shorter than the rest of the hooks. The arrangement of the hooks is characteristic of North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in man. Range inmm 1 0.014 0.013-0.017 2 0.016 0.013-0.019 3 0.017 0.014-0.019 4 0.018 0.015-0.019 5 0.016 0.013-0.019 6 0.017 0.013-0.019 7 0.017 0.013-0.019
The anterior eye spots are smaller and invariably farther apart than members of the posterior pair.
Reproductive system.—Gonads situated near the middle of the body, testis ovate and situated posterior to ovary. Vas deferens passes forward on left side of body and expands to form a fusiform seminal vesicle near the cirrus base. Prostate glands two in number, larger one somewhat fusiform in shape and filled with a finely granular colorless fluid, smaller one subpyriform in outline and filled with a coarsely granular yellowish fluid. Copulatory complex well developed and situated in a relatively small vestibule. Cirrus a curved chitinous tube reciprocally coiled about the accessory piece. Accessory piece a curved chitinous rod. A conspicu- ous knob which serves as a site for muscular attachment occurs on the anterior portion of the accessory piece. Contractile elements arise on posterior portion of this knob and insert on the cirrus base. On con- traction of these structures the anterior portion of the accessory piece remains im situ, the portion of the accessory piece posterior to the knob bends in an elbow fashion and the cirrus is projected through the vestibular pore for a distance equal to about one half its length. The terminal portion of the accessory piece serves as a guide for the cirrus. Presumably, the retraction of the cirrus is accomplished by straightening of the accessory piece.
Ovary ovate, smaller than testis and situated anterior to it. Egg pore on ventral surface, on right of copulatory complex base. Vagina present on left body margin, anterior to middle of body proper; vaginal canal a long chitinous tube connecting vagina with the well-developed seminal receptacle. Vitellaria and vitelline ducts as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland a cluster of glandular cells surrounding the odtype.
Digestive and excretory systems.—The digestive and excretory sys-
22 ILLINOIS BIOLOGICAL MONOGRAPHS
tems are as described in the general morphology of the North American
fresh-water Tetraonchinae. Average diameter of pharynx 0.139 mm. (0.082-0.164 mm.).
Systematic position.—This parasite has been found to occur in heavy infestations on the gills of the black crappie from Lake Senachwine, Henry, Ill. Another form, Cleidodiscus vancleavei Mizelle, 1936, also occurs on the same host, but the two species have not been recovered from the same host specimen. Cleidodiscus capax occurs in smaller num- bers on the gills of the white crappie, in mixed infestations with Cleidodiscus longus Mizelle, 1936, Cleidodiscus uniformis Mizelle, 1936, and Cleidodiscus vancleavei. In size, this form closely approximates that ot Cleidodiscus robustus Mueller, 1934, but the anchors, bars, copulatory complex, and vagina are morphologically different from corresponding structures in C. robustus. C. capax occurs only on the black and white crappies, whereas C. robustus has been taken from the pumpkinseed, bluegill, green sunfish, “‘sunfish,’’ and “bass” (Mueller, 1936). Tetra- onchid parasites of crappies (black and white) have not been found to occur on other hosts in this investigation. One hundred per cent infesta- tion with C. capax was recorded for: forty-eight white crappies from Lake Decatur, Decatur, Ill., in May, June, July, and August, 1936; sixteen black crappies from Lake Senachwine, Henry, IIl.; and five black crappies from the Illinois River, Havana, IIl., in June, 1936.
Cleidodiscus longus Mizelle, 1936 Figs. 4, 49-56 Hosts and Localities: White Crappie (Pomoxis annularis), Lake Decatur, Decatur, Ill.; Salt Fork of the Big Vermilion River, south of Oakwood, Ill.; Boomer Creek, Stillwater, Okla. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9080.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.626 mm. (0.492-0.713 mm.), average width at level of cephalic lobes 0.087 mm. (0.066-0.107 mm.), greatest body width average 0.106 mm. (0.098-0.123 mm.), average width of peduncle at junction with haptor 0.064 mm. (0.038-0.086 mm.). Haptor distinct, hexagonal in shape, and broader than long, average width 0.110 mm. (0.076-0.123 mm.), average length 0.100 mm. (0.057- 0.114 mm.). Ventral bar with notched ends, relatively straight, heavier and slightly longer than dorsal bar which is bent in middle to present a sagged appearance. Average length of ventral bar 0.038 mm. (0.032- 0.042 mm.), average length of dorsal bar 0.037 mm. (0.028-0.042 mm.). Anchors similar in shape, bases bifurcate, superficial roots longer than deep roots. Wings on anchor shafts clearly discernible. Distal portion
STUDIES ON TREMATODES—MIZELLE 23
of each anchor shaft markedly dilated and containing a cavity which extends into basal portion of each point. Anchor points and shafts unite to form an internal angle at locus of junction. Ventral anchors larger than dorsal anchors. Average length of ventral anchors 0.043 mm. (0.038-0.051 mm.), average width 0.028 mm. (0.019-0.032 mm.), average length of dorsal anchors 0.037 mm. (0.031-0.046 mm.), average width 0.017 mm. (0.013-0.023 mm.). Bases of ventral anchors conspicuously wider than bases of dorsal anchors. Hook bases of pair number five ovate and shorter than their respective shafts, bases of other hooks elongate-ovate and about same length as their shaits. Hooks of pair number five noticeably shorter than rest of hooks. The arrangement of the hooks is characteristic of North American Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range in main. 1 0.017 0.015-0.019 2 0,020 0.017-0.023 3 0.021 0.019-0.023 4 0.019 0.017-0.023 5 0.014 0.009-0.017 6 0.019 0.015-0.021 7 0.021 0.017-0.023
The anterior eye spots are smaller and invariably farther apart than members of the posterior pair.
Reproductive system.—Gonads located anteriorly in posterior half of body, testis elongate and located posterior to ovary. Vas deferens arises from anterior end of testis, passes forward on leit side of body without evident dilatation to form a seminal vesicle. Two prostate glands present, larger one elongate-saccate in outline and filled with a finely granular colorless fluid, the smaller one saccate and containing a coarsely granular yellowish fluid. Each prostate gland empties into base of cirrus by a single individual duct. Copulatory complex well developed and situated in a slender vestibule. Cirrus a long chitinous whip-like tube attenuated distally to a fine thread. Accessory piece consists of a chitinous struc- ture with a deep groove which serves as a guide for the cirrus. Con- tractile elements originate on the accessory piece near its midportion and insert on the base of the cirrus. On contraction of these elements, the portion of the accessory piece distal to the muscular attachments remains im situ, the proximal portion bends in elbow fashion and the cirrus is pro- jected through the vestibular pore, beyond the body surface, for a distance equal to about one-half its length. Presumably, the straightening of the accessory piece retracts the cirrus.
Ovary ovate, from one to two times as large as testis and situated anterior to it. Uterine pore located on ventral surface at right of copula-
24 ILLINOIS BIOLOGICAL MONOGRAPHS
tory complex base. Vagina present on left margin near the middle of the body ; vaginal canal a chitinous tube emptying mesially into a well-defined seminal receptacle. The vitellaria and vitelline ducts are as described in the general morphology for the North American fresh-water Tetraonchinae. Shell gland, a group of glandular cells surrounding the ootype.
Digestive and excretory systems.—The digestive and excretory sys- tems exist as described in the general morphology of the North American
fresh-water Tetraonchinae. Average diameter of pharynx 0.033 mm. (0.030-0.036 mm.).
Systematic position.—This species of gill parasite has been recovered only from the white crappie in this investigation. It occurs in mixed infestations with Cleidodiscus vancleavei Mizelle, 1936, Cleidodiscus capax Mizelle, 1936, and Cleidodiscus uniformis Mizelle, 1936. Clei- dodiscus longus possesses a copulatory complex similar to but longer than that of C. uniformis. The vaginae of the two species are almost identical. The chief differences are the dissimilarities of bars and anchors of these two species. The bases of the two pairs of anchors of C. longus are markedly different in width, whereas the widths of the two pairs of anchors of C. uwniformis are almost identical. Average width of ventral anchors of C. longus 0.028 mm., average width of dorsal anchors 0.017 mm, Average width of ventral anchors of C. uniformis 0.017 mm., average width of dorsal anchors 0.016 mm. C. longus possesses anchors whose shafts are markedly dilated distally while the anchors of C. uni- formis are never more than slightly dilated. Each anchor shaft of C. longus meets its respective point to form an internal angle, but the shafts of C. uniformis are uniformly recurved without formation of an angle at this point.
The bars of the two species are different and constant in shape. C. uniformis is the closest morphological relative of C. longus.
Forty-eight white crappies from Lake Decatur, Decatur, Il., in May, June, July, and August, 1936, were infested one hundred per cent with this gill parasite. Only one host was taken from the Salt Fork of the Big Vermilion River south of Oakwood, Ill, July, 1936. Five hosts from Boomer Creek, Stillwater, Okla., were infested one hundred per cent with this species.
Cleidodiscus uniformis Mizelle, 1936 Figs. 12, 85-93
Hosts and Localities: White crappie (Pomoxts annularis), Lake Decatur, Decatur, ll.; Salt Fork of the Big Vermilion River, south of Oakwood, Ill.; Boomer Creek, Stillwater, Okla.
Location: Gills.
Specimens: U.S.N.M. Helm. Coll. No. 9081.
STUDIES ON TREMATODES—MIZELLE 25
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.583 mm. (0.398-0.738 mm.), average width at level of cephalic lobes 0.080 mm. 0.065-0.114 mm.), greatest body width average 0.097 mm. (0.075-0.147 mm.), average width of peduncle at junction with haptor 0.062 mm. (0.034-0.092 mm.). Haptor distinct, hexagonal in shape and broader than long, average width 0.107 mm. (0.076-0.127 mm.), average length 0.093 mm. (0.062-0.114 mm.). Ventral bar about size of dorsal bar, but straighter and with anterior surface raised in the midportion. Dorsal bar slightly bent ventrally in the middle and with obliquely truncate ends. Average length of ventral bar 0.036 mm. (0.029-0.038 mm.), average length of dorsal bar 0.036 mm. (0.030-0.040 mm.). Anchors similar in shape and size, bases bifurcate, superficial roots longer than deep roots. Wings clearly evident on all four anchor shafts. Anchors hollow distally, regularly recurved without formation of an angle at junction with points. Hollow portion of shaft continued into base of anchor point. Bases of dorsal and ventral anchors not markedly different in width. Average length of ventral anchors 0.032 mm. (0.026-0.034 mm.), average width 0.017 mm. (0.013-0.019 mm.), average length of dorsal anchors 0.032 mm. (0.026- 0.036 mm.), average width 0.016 mm. (0.013-0.018 mm.). Hook bases ovate to elongate-ovate in shape. Hooks of pairs numbers one and five shorter than other hooks. The arrangement of the hooks is as described in the general morphology of the North American fresh-water Tetra- onchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range in mim. 1 0.015 0.011-0.017 2 0.019 0.015-0.021 3 0.020 0.015-0.023 4 0.021 0.015-0.023 5 0.015 0.010-0.017 6 0.021 0.015-0.023 7 0.020 0.015-0.023
Spatial relationships between members of the pairs of eye spots variable, anterior pair smaller.
Reproductive system.—Gonads situated anteriorly in the second halt of body, testis ovate, slightly smaller than, and located dorsoposterior to ovary. Vas deferens arises from anterior end of testis, passes forward near midline of body and enters cirrus base without evident dilatation to form a seminal vesicle. Two prostate glands present, larger one irreg~ ularly saccate and filled with a finely granular fluid, smaller one elongate and containing a coarsely granular, yellowish fluid. Copulatory complex well developed and situated in a slender vestibule. Cirrus a long chitinous whip-like tube attenuated distally to a fine thread. Accessory piece a
26 ILLINOIS BIOLOGICAL MONOGRAPHS
chitinous structure with a deep groove which serves as cirrus guide. Muscular elements originate about midway on accessory piece and insert on base of cirrus. On contraction of these elements the portion of the accessory piece anterior to the attachment remains in situ, the portion of the accessory piece posterior to the attachment bends in elbow fashion and the cirrus is projected ventrally, through the vestibular pore, for a distance equal to about one-half its length.
Ovary ovate, slightly larger than testis and situated anteroventrally to it. Egg pore located on ventral surface on right of vestibular pore. Vagina present on left margin in anterior body half, vaginal canal a relatively long chitinous tube terminating at the well-developed seminal receptacle. Vitellaria and vitelline ducts are as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—The digestive and excretory systems exist as described in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.034 mm.
(0.030-0.048 mm. ).
Systematic position.—This parasite, from Illinois localities, has been found to occur in mixed infestations with Cleidodiscus vancleavei Mizelle, 1936, Cleidodiscus capax Mizelle, 1936, and Cleidodiscus longus Mizelle, 1936. It has been recovered only from the gills of the white crappie. The vagina of this species is almost identical with that of C. longus. Whereas , the shafts of C. longus are markedly dilated to form an internal angle at the junction with the points, the converse condition exists in the anchors of C. uniformis. The anchor shafts of C. uniformis are never more than slightly dilated, hollow and regularly recurved without forma- tion of an angle at the locus mentioned above for C. longus. The ventral anchor bases of C. Jongus are much wider than are the dorsal anchor bases. The dorsal and ventral anchor bases of C. uniformis are almost identical in width. Average width of ventral anchor bases of C. longus 0.028 mm., average width of dorsal anchor bases 0.017 mm.; average width of ventral anchor bases of C. uniformis 0.017 mm., average width of dorsal anchor bases 0.016 mm. In addition to the above differences, the bars of the two species are constantly different in shape. C. longus 1s the nearest morphological relative of C. wniformis.
Forty-eight white crappies from Lake Decatur, Decatur, Ill, in May, June, July, and August, 1936, were one hundred per cent infested with this parasite. Only one host was taken from the Salt Fork of the Big Vermilion River south of Oakwood, IIL, July, 1936. Five hosts from Boomer Creek, Stillwater, Okla., were infested one hundred per cent with this species.
STUDIES ON TREMATODES—MIZELLE 27
Cleidodiscus vancleavei Mizelle, 1936 Figs. 5, 31-39 Hosts and Localities: White and Black Crappies (Pomoxis annularis and P sparoides), Lake Decatur, Decatur, Ill.; Salt Fork of the Big Vermilion River, south of Oakwood, Ill.; Boomer Creek, Stillwater, Okla. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9082. Synonyms: Onchocleidus formosus Mueller, 1936; C. formosus (Mueller, 1936)
Price, 1937.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.563 mm. (0.399-0.681 mm.), average width at level of cephalic lobes 0.068 mm. (0.042-0.089 mm.), greatest body width average 0.070 mm. (0.057-0.089 mm.), average width of peduncle at junction with haptor 0.047 mm. (0.036-0.067 mm.). Haptor distinct, hexagonal in shape and broader than long, average width 0.104 mm. (0.089-0.124 mm.), average length 0.086 mm. (0.074- 0.105 mm.). Dorsal bar notched at each end and with a median spine on the posterior border. Ends of ventral bar variable in shape, median posterior spine present. Average length of ventral bar 0.024 mm. (0.019- 0.029 mm.), average length of dorsal bar 0.025 mm. (0.019-0.029 mm.). Anchors similar in shape, bases slightly bifurcate, superficial roots longer than deep roots, wings clearly evident. Each anchor shaft solid, junction with point marked by an internal angle. Ventral anchors slightly longer than dorsal anchors. Bases of dorsal and ventral anchors not noticeably different in width. Average length of ventral anchors 0.039 mm. (0.033- 0.044 mm.), average width 0.019 mm. (0.013-0.023 mm.), average length of dorsal anchors 0.036 mm. (0.029-0.042 mm.), average width 0.017 mm. (0.015-0.019 mm.). Hook bases of pair number five ovate and shorter than shafts, bases of remaining hooks elongate. Bases of pair number one about same length as their shafts, bases of remaining hooks longer than their respective shafts. Hooks of pair number five noticeably shorter than the other hooks. The arrangement of the hooks is character- istic of North American Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range im mam. 1 0.018 0.013-0.019 2 0.020 0.017-0.023 3 0.019 0.015-0.023 4 0.022 0.019-0.025 5 0.013 0.011-0.015 6 0.021 0.017-0.025 7 0.024 0.019-0.027
The anterior eye spots are smaller and farther apart than members of the posterior pair.
Reproductive system.—Gonads situated anteriorly in posterior body
28 ILLINOIS BIOLOGICAL MONOGRAPHS
half, testis relatively small and located posterior to ovary. Vas deferens dilated near cirrus base to form a tubular seminal vesicle. Two prostate glands, one containing a finely granular colorless fluid, the other filled with a coarsely granular faintly yellowish fluid. Copulatory complex well developed and situated in a small vestibule. Cirrus a short chitinous tube, base relatively large, shaft tapered to a point distally. Accessory piece a chitinous structure of variable shape. It encloses the base of the cirrus and usually makes one complete turn around the cirrus shaft. Operation of copulatory complex not observed.
Ovary ovate, much larger than testis and situated anterior to it. Egg pore on ventral surface anterior to base of copulatory complex. Vagina on left margin near midlength of body; vaginal canal short, emptying mesially into a transparent seminal receptacle. Vitellaria and vitelline ducts exist as described in the general morphology of the North American fresh-water Tetraonchinae. Nature of shell gland not determined.
Digestive and excretory systems.—The digestive and excretory sys- tems are as given in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.025 mm. (0.023-0.028 mm. ).
Systematic position.—This parasite, from Illinois localities, has been recovered from the gills of the white crappie, in mixed infestations with Cleidodiscus capax Mizelle, 1936, Cleidodiscus longus Mizelle, 1936, and Cleidodiscus uniformis Mizelle, 1936. It has been recovered from the gills of the black crappie in pure infestations. C. capax also occurs on the black crappie, but in this investigation these two parasites have not been recovered from the same host specimen. While the general morphology of Cleidodiscus vancleavei is similar to that of the rest of the members of the genus, the characteristic copulatory complex, together with the presence of spines on both the dorsal and ventral bars distinguish it immediately from all related forms. In May, June, July, and August, 1936, forty-eight white crappies from Lake Decatur, Decatur, IIl., were found one hundred per cent infested with this helminth. Only one host (white crappie) was taken from the Salt Fork of the Big Vermilion River. Six black crappies from Lake Decatur in June, 1936, were infested only fifty per cent with this parasite.
Mueller (1936a) described this parasite from the gills of the black crappie from Lake Okeechobee, Clewiston, Fla., as Onchocleidus formosus. The sinistral vagina and the copulatory complex with the accessory piece articulated to the cirrus base, definitely places this form in the genus Cleidodiscus Mueller, 1934. Mueller’s specimens of O. formosus have been compared with specimens of C. vancleavei, and forms showing variation in the ventral bar and accessory piece identical
STUDIES ON TREMATODES—MIZELLE 29
with Mueller’s figures have been taken from the black and white crappies in Hlinois and Oklahoma.
Cleidodiscus bedardi Mizelle, 1936 Figs. 6, 57-66 Host and Localities: Long-Eared Sunfish (Xenotis megalotis), Embarrass River, Urbana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9083.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.412 mm. (0.285-0.495 mm.), average width at level of cephalic lobes 0.056 mm. (0.047-0.067 mm.), greatest body width average 0.080 mm. (0.057-0.103 mm.), average width of peduncle at junction with haptor 0.057 mm. (0.038-0.065 mm.). Haptor distinct, subdiscoidal in shape and broader than long, average width 0.087 mm. (0.059-0.100 mm.), average length 0.058 mm. (0.051-0.067 mm.). Ventral bar noticeably larger than dorsal bar and variable in shape. Both bars bent near middle, dorsal bar always bent posteriorly, ventral bar may be bent either anteriorly or posteriorly. Average length of ventral bar 0.031 mm. (0.027-0.036 mm.), average length of dorsal bar 0.024 mm. (0.023-0.025 mm.). Anchors similar in shape, bases bifurcate, superficial roots slightly longer than deep roots. Anchor shafts solid, suggestion of internal angle at junction of shaft and point. Ventral anchor slightly longer than dorsal anchors. Ventral anchor bases not conspicuously wider than dorsal anchor bases. Average length of ventral anchors 0.027 mm. (0.023-0.034 mm.), average width 0.012 mm. (0.009-0.015 mm.), average length of dorsal anchors 0.024 mm. (0.021-0.032 mm.), average width 0.011 mm. (0.009-0.015 mm.). Hooks not conspicuously different in length. Bases of hooks ovate, bases of pair number five shorter than shafts, bases of other hooks about same length as their respective shafts. The arrangement of hooks is as described in the general morphology of the North American Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range iw mm 1 0.013 0.011-0.015 2 0.014 0.011-0.015 3 0.014 0.013-0.015 4 0.014 0.013-0.015 5 0.012 0.009-0.013 6 0.015 0.013-0.016 vf 0.014 0.013-0.015
Anterior eye spots smaller and generally farther apart than members of posterior pair.
30 ILLINOIS BIOLOGICAL MONOGRAPHS
Reproductive system.—Gonads located in posterior body half, testis ovate, situated dorsoposterior to and much smaller than ovary. Vas deferens passes forward generally on left side of body as a slightly undulant tube dilated near cirrus base to form a fusiform seminal vesicle. Only one prostate gland observed; it is saccate and contains a coarsely granular yellowish fluid. Copulatory complex well developed and situated in a relatively large vestibule. Cirrus a simple curved chitinous tube tapered distally to a fine point. Accessory piece a solid chitinous rod with a chelate termination. Operation of cirrus not observed.
Ovary subspherical, much larger than, and situated anteroventrally to the testis. Egg pore on ventral surface on right of copulatory complex. Vagina present on left margin near midlength of body; vaginal canal short, emptying into a small seminal receptacle lying parallel to the lateral margin of body. A pseudovagina (Fig. 64) occurs immediately anterior to the vagina. Vitellaria and vitelline ducts exist as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland a thickened portion of the oviduct.
Digestive and excretory systems.—The digestive and excretory sys- tems are as described in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.025 mm. (0.021-0.032 mm.). A large solenocyte occurs in the region of the seminal receptacle.
Systematic position.—This parasite, from Illinois localities, occurs in mixed infestations with Actinocleidus articularis (Mizelle, 1936), Onchocleidus distinctus Mizelle, 1936, Pterocleidus acuminatus (Mizelle, 1936), an undescribed species of Cleidodiscus Mueller, 1934, and an un- described member of the genus Haplocleidus Mueller, 1937. Cleidodiscus bedardi has been taken only from the gills of the long-eared sunfish from the Embarrass River south of Urbana, Ill. It is immediately recognizable by the striking difference in the size of the dorsal and ventral bars, the ventral being much larger; the presence of a pseudovagina; and a chelate accessory piece. The anchors are relatively small with deeply bifurcate bases. These structural details taken together are radically different from those of any other described member of the genus Cleidodiscus.
One hundred per cent infestation was recorded for one hundred twenty-five long-eared sunfish, from the Embarrass River in April, May, June, July, and August, 1936.
Cleidodiscus diversus sp. nov. Figs. 141-147 Host and Localities: Green Sunfish (Apomotis cyanellus), Embarrass River, Urbana, Ill.; Boomer Creek, Stillwater, Okla. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9139.
STUDIES ON TREMATODES—MIZELLE il
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.340 mm. (0.205-0.394 mm.), greatest body width (near peduncle) average 0.061 mm. (0.052-0.085 mm.). Haptor distinct, hexagonal and broadly connected to peduncle. Ventral bar variable in shape, heavier and slightly longer than dorsal bar which is bent in middle to present a sagged appearance. Average length of ventral bar 0.029 mm. (0.025-0.034 mm.), average length of dorsal bar 0.021 mm. (0.019-0.023 mm.). Anchors similar in size and shape, bases bifurcate; wings on anchor shafts clearly discernible. Anchor points and shafts unite to form an internal angle at locus of junction, Average length of ventral anchors 0.025 mm. (0.021-0.032 mm.), average length of dorsal anchors 0.025 mm. (0.022-0.029 mm.). Each of the fourteen hooks is differentiated into a base, shaft, sickle-shaped termina- tion, and opposable piece. Hook lengths 0.013-0.019 mm. Hook bases elongate-ovate and about same length as shafts. The arrangement of the hooks is characteristic of North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62). The anterior eye spots are smaller and generally farther apart than members of the posterior pair.
Reproductive system.—Gonads located anteriorly in posterior half of body; vas deferens arises from anterior end of testis, passes forward as a slightly undulant tube. Copulatory complex well developed and situ- ated in a relatively large vestibule. Cirrus a short chitinous tube with a large base and tapered shaft, length 0.034 mm. (0.027-0.043 mm.). Accessory piece a doubly recurved chitinous structure with a knob near the midportion and with a forked termination. Operation of cirrus not observed.
Ovary ovate; egg pore located on ventral surface near vestibular pore. Vagina present on leit margin near the middle of the body. The vitellaria and vitelline ducts are as described in the general morphology for the North American fresh-water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—The digestive and excretory sys- tems exist as described in the general morphology of the North American
fresh-water Tetraonchinae. Average diameter of pharynx 0.021 mm. (0.017-0.027 mm.)
Systematic position —Cleidodiscus diversus occurs in mixed infesta- tions with Cleidodiscus robustus Mueller, 1934, Onchocleidus cyanellus n. sp., Actinocleidus longus n. sp., and an undescribed member of the genus Actinocleidus Mueller, 1937. C. diversus possesses anchors similar to those of Cleidodiscus bedardi Mizelle, 1936, and a copulatory complex like that of Actinocleidus fergusoni, n. sp. The former species occurs on
32 ILLINOIS BIOLOGICAL MONOGRAPHS
the long-eared sunfish, the latter on the bluegill, and C. diversus on the green sunfish. One hundred per cent infestation with this parasite is recorded for twenty-six green sunfish from the Embarrass River in May, 1937.
Genus Onchocleidus Mueller, 1936
Diagnosis.—Tetraonchinae with intestine bifurcate but confluent pos- teriorly. Vagina present or absent; when present it lies on the right body margin near the midlength. Copulatory complex weakly developed, cirrus a slender chitinous tube, at times with a fin or cirral thread around the shaft, at times corkscrew-like in nature. Accessory piece may be wanting but when present its base is not articulated with the cirrus base. Haptor generally distinct, hexagonal or pentagonal in shape. Fourteen hooks present, each of which may be solid and differentiated into a base, shaft, sickle-shaped termination and opposable piece, but generally exists as a solid or hollow cylindrical structure with a sickle-shaped termination and opposable piece distally. Parasitic on the gills of fresh-water fishes. Type species, O. ferox (Mueller, 1934).
Onchocleidus principalis Mizelle, 1936 Figs. 3, 76-84 Hosts and Localities: Kentucky Bass (Micropterus pseudaplites) and Small-Mouth
Bass (Micropterus dolomieu), Salt Fork of the Big Vermilion River, Homer,
Ill. Large-Mouth Bass (Aplites salmoides), Lake Senachwine, Henry, III. Location: Gills.
Specimens: U.S.N.M. Helm. Coll. No. 9085. Synonym: Onchocleidus contortus Mueller, 1937.
General anatomy.—Relatively small parasites devoid of body scales and internal spicules. Average length 0.467 mm. (0.369-0.631 mm.), average width at level of cephalic lobes 0.079 mm. (0.066-0.108 mm.), greatest body width average 0.096 mm. (0.070-0.127 mm.), average width of peduncle at junction with haptor 0.057 mm (0.028-0.070 mm.). Haptor distinct, hexagonal in shape and broader than long, average width 0.098 mm. (0.078-0.125 mm.), average length 0.066 mm. (0.051-0.082 mm.). Ventral bar relatively straight and heavier than dorsal bar. Dorsal bar with midportion noticeably curved posteriorly, slightly shorter than ventral bar and with a notch on posterior margin near each end. Average length of ventral bar 0.036 mm. (0.032-0.042 mm.), average length of dorsal bar 0.035 mm. (0.030-0.044 mm.). Anchors similar in shape, wings slightly visible. Shaft and point of each anchor solid and relatively regu- larly recurved without formation of a distinct internal angle at their junction. Ventral anchors slightly longer than dorsal anchors. Average length of ventral anchors 0.033 mm. (0.028-0.038 mm.), average width 0.018 mm. (0.015-0.021 mm.), average length of dorsal anchors 0.031
STUDIES ON TREMATODES—MIZELLE 33
mm. (0.027-0.034 mm.), average width 0.015 mm. (0.013-0.017 mm.). Bases of ventral anchors larger but not conspicuously wider than bases of the dorsal anchors. Each of the fourteen hooks differentiated into a base, shaft, sickle-shaped termination and opposable piece. Hook bases elon- gate, bases of pair number one about same length as their shafts, bases of pair number five shorter than their shafts, bases of remaining hooks slightly longer than their shafts. Hooks of pairs numbers one and five shorter than other hooks. The arrangement ot the hooks is as described in the general morphology of the North American fresh-water Tetra- onchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length im min. Range im min 1 0.017 0.013-0,019 2 0.020 0.019-0.023 3 0.020 0.019-0.023 4 0.021 0.019-0,024 5 0.015 0.013-0.019 6 0.020 0.019-0.025 vf 0.021 0.019-0.025
Anterior eye spots smaller and about the same distance apart as members of the posterior pair. In life, a refractile area is present immediately in front of each anterior eye spot.
Reproductive system.—Gonads located in posterior body halt, testis ovate and situated dorsal to ovary. Vas deferens passes forward on left side of body and expands into a relatively large fusiform seminal vesicle just posterior to cirrus base. Two prostate glands present, larger one tubular and filled with a finely granular hyaline fluid, smaller gland an elongate bulb-like structure containing a coarsely granular yellowish fluid. Each prostate empties into base of cirrus by a single individual duct. Copulatory complex weakly developed and situated in a relatively small vestibule. Cirrus a chitinous corkscrew-like tube emptying ven- trally through the vestibular pore. Accessory piece a solid chitinous structure about three-fifths the length of cirrus and with a forked term- ination which is often complete to form a ring through which the cirrus passes. Operation of cirrus not observed.
Ovary ovate and about two to three times as large as the testis. Ege pore located on the ventral surface at right of cirrus base. Vagina present on right margin about midway the body length; vaginal canal an undulant, lightly chitinized tube, often with one or two loose coils; seminal receptacle conspicuous. The vitellaria and vitelline ducts are as described in the general morphology of the North American fresh-water Tetraonchinae.
Digestive and excretory systems.—The digestive system agrees with
34 ILLINOIS BIOLOGICAL MONOGRAPHS
the description given for the North American fresh-water Tetraonchinae. Average diameter of the pharynx 0.029 mm. (0.025-0.034 mm.). Excre- tory system as described for the North American fresh-water Tetra- onchinae, but an additional pair of ducts occur at level of seminal re- ceptacle. One of these ducts is present on each side of the body and passes toward the lateral body margins. Openings for these structures have not been observed. Two very large solenocytes are present, one is located at the level of the ovary and the other near the posterior end of the seminal vesicle.
Systematic position—This parasite is singular in that each of the fourteen hooks is differentiated into a base, shaft, sickle-shaped termina- tion and opposable piece. While this character is common to the genus Cleidodiscus Mueller, 1934, the possession of other characters as vagina on right margin, and accessory piece not articulated to the cirrus base definitely places it in the genus Onchocleidus Mueller, 1936. The bars, anchors, vaginal tube, and hooks are distinctive.
Mueller (1937) described this parasite as Onchocleidus contortus from the large-mouth bass in Florida. The distal portion of the acces- sory piece of O. principalis was originally described (Mizelle, 1936) as forming a ring through which the cirrus projected. Mueller (1937) distinguished O. contortus from O. principalis by the forked termination of the accessory piece. This structural variation of the accessory piece was earlier recognized by the present author. Specimens of these two species have been compared and found to be identical. Hosts, for this species, have been found one hundred per cent infested.
Onchocleidus interruptus Mizelle, 1936 Figs. 2, 103-108 Host and Localities: Yellow Bass (Morone interrupta), Lake Decatur, Decatur, Ill.; Lake Senachwine, Henry, Il. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9088.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.407 mm. (0.285-0.508 mm.), average width at level of cephalic lobes 0.073 mm. (0.067-0.080 mm.), greatest body width average 0.085 mm. (0.066-0.104 mm.), average width of peduncle at junction with haptor 0.057 mm. (0.046-0.070 mm.). Hap- tor distinct, hexagonal in shape and broader than long, average width 0.097 mm. (0.086-0.133 mm.), average length 0.078 mm. (0.066-0.095 mm.). Ventral bar slightly longer than dorsal bar and with a cavity in its posterior midportion. Both bars slightly bent in the middle. Average length of ventral bar 0.033 mm. (0.029-0.044 mm.), average length of
STUDIES ON TREMATODES—MIZELLE 3
mn
dorsal bar 0.030 mm. (0.027-0.036 mm.). Anchors similar in shape, bases bifurcate superficial roots longer than deep roots. Anchor wings clearly perceptible. Each anchor shaft solid and uniting with its point to form an internal angle at junction. Ventral anchors longer than dorsal anchors. Average length of ventral anchors 0.045 mm. (0.040-0.052 mm.), aver- age width 0.024 mm. (0.019-0.032 mm.), average length of dorsal anchors 0.040 mm. (0.036-0.050 mm.), average width 0.014 mm. (0.013-0.021 mm.). Bases of ventral anchors noticeably wider than bases of dorsal anchors. Each hook, except pair number five, consists of an elongate chitinous body with an opposable piece and sickle-shaped termination. Each hook of pair number five is differentiated into a base, shaft, sickle- shaped termination, and opposable piece. Hooks of pair number one longer, and hooks of pair number five conspicuously shorter than rest of hooks. The arrangement of hooks is as given in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in min. Range in mm. 1 0.032 0.028-0.040 2 0.024 0.021-0.025 3 0.024 0.021-0.027 4 0.023 0.019-0.032 5 0.013 0.011-0.015 6 0.026 0.021-0.032 7 0.029 0.027-0.034
The spatial relationships between members of the two pairs of eye spots variable, anterior pair smaller.
Reproductive system.—Gonads situated anteriorly in the posterior body half, testis ovate, from four to six times as large as ovary and located posterior to it. Vas deferens dilated immediately posterior to cirrus base to form a conspicuous seminal vesicle. Two prostate glands present, large one saccate, filled with a finely granular, colorless fluid, smaller one botuliform and containing a coarsely granular yellowish fluid. Copulatory complex weakly developed and enclosed within a slender vestibule. Cirrus a short, straight, chitinous tube attenuated distally, expanded terminally, and with a cirral thread around the shaft. Accessory piece solid, with a key-hole effect distally through which one of the loops of the cirral thread passes. Operation of copulatory com- plex not fully understood.
Ovary subspherical, much smaller than testis and situated anterior to it. Egg pore on ventral surface on right of copulatory complex. Vagina and seminal receptacle wanting in this species. Vitellaria and vitelline ducts are as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland not observed.
36 ILLINOIS BIOLOGICAL MONOGRAPHS
Digestive and excretory systems.—The digestive and excretory sys- tems are as described in the general morphology of the North American
fresh-water Tetraonchinae. Average diameter of pharynx 0.028 mm. (0.023-0.032 mm.).
Systematic position.—This parasite has been collected only from the gills of the yellow bass. It is the only monogenetic form recorded from this host. Onchocleidus interruptus is easily recognized by the massive testis and the characteristic bars and anchors. The shafts of the ventral anchors are noticeably bent in the direction of the points. The copu- latory complex resembles that of Onchocleidus distinctus Mizelle, 1936, a form which occurs on the long-eared sunfish. Sixty-five hosts from Lake Decatur in May, June, July, and August, 1936, and eight hosts from Lake Senachwine in June, 1936, were infested one hundred per cent with O. interruptus.
Onchocleidus mucronatus Mizelle, 1936 Figs. 9, 22-30 Hosts and Localities: Bluegill Sunfish (Helioperca macrochira), Orange-spotted
Sunfish (Allotis humilis), Pumpkinseed Sunfish (Eupomotis gibbosus), Hybrid
between Bluegill and Pumpkinseed Sunfishes and Hybrid between Orange-
spotted and Pumpkinseed Sunfishes, Lake Senachwine, Henry, Ill.—Bluegill
Sunfish, Lake Decatur, Decatur, Ill.; Boomer Creek, Stillwater, Okla.—
Orange-spotted Sunfish, Salt Fork of the Big Vermilion River, Homer, Il. Location: Gills.
Specimens: U.S.N.M. Helm. Coll. No. 9087.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.503 mm. (0.426-0.820 mm.), average width at level of cephalic lobes 0.051 mm. (0.041-0.098 mm.), greatest body width average 0.065 mm. (0.051-0.131 mm.), average width of peduncle at junction with haptor 0.042 mm. (0.019-0.075 mm.). Haptor distinct, hexagonal or pentagonal in shape and broader than long, average width 0.101 mm. (0.070-0.148 mm.), average length 0.098 mm. (0.076-0.139 mm.). Each bar possesses a spine projecting from middle of posterior margin. Average length of ventral bar 0.022 mm. (0.019- 0.024 mm.), average length of dorsal bar 0.024 mm. (0.021-0.025 mm.). Wings on anchor shafts delicate. Anchors similar in shape, bases slightly bifurcate, superficial roots longer than deep roots. Anchor shafts solid and unite with anchor points to form an internal angle at junction. Anchors approximately same size. Average length of ventral anchors 0.057 mm. (0.051-0.067 mm.), average width 0.014 mm. (0.009-0.019 mm.), average length of dorsal anchors 0.057 mm. (0.051-0.074 mm.), average width 0.012 mm. (0.009-0.019 mm.). Each hook, except pair number five, has an elongate chitinous body, a sickle-shaped termination, and opposable piece. Each hook of pair number five possesses a base,
STUDIES ON TREMATODES—MIZELLE 37
shaft, sickle-shaped termination and opposable piece. Hooks of pairs numbers one and seven with apparent cavity, members of pair number two often with slight cavity. Hooks of pair number one noticeably longer and hooks of pair number five conspicuously shorter than other hooks. The arrangement of the hooks is as given in the general mor- phology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range in mm. 1 0.035 0.030-0.043 2 0.026 0.023-0.032 3 0.030 0.025-0.037 4 0.032 0.028-0.038 5 0.013 0.010-0.015 6 0.033 0.028-0.038 7 0.031 0.028-0.044
Anterior eye spots smaller and usually farther apart than members of the posterior pair.
Reproductive system.—Gonads located in posterior half of body, testis subspherical, located posterior to, and from two to three times as large as ovary. Vas deferens passes forward generally making one loop in front of vaginal canal and dilates posterior to cirrus base to form an elongate seminal vesicle. Two prostate glands present, larger one banana-shaped, containing a finely granular colorless fluid, smaller one saccate and filled with a coarsely granular yellowish fluid. Each prostate gland empties into cirrus base by a single individual duct. Copulatory complex weakly developed and enclosed within a slender vestibule. Cirrus a chitinous tube with a cirral thread around the shaft. Accessory piece a solid chitinous structure with a key-hole effect distally through which the cirrus projects. Muscular elements arise on accessory piece and insert on base of cirrus; on contraction of these elements the accessory piece remains in situ, and the cirrus is projected ventrally, through the vestibular pore, a short distance beyond the body surface. Retraction of cirrus not fully understood.
Ovary subspherical, about one-third to one-half the size of testis and situated anterior to it. Egg pore on ventral surface near vestibular pore. Vagina on right body margin near midlength; vaginal canal a short zigzag, chitinous tube emptying into a small bag-like seminal receptacle. Vitellaria and vitelline ducts as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland a cluster of cells surrounding the ootype.
Digestive and excretory systems—Digestive and excretory systems as given in the general morphology of the North American fresh-water
38 ILLINOIS BIOLOGICAL MONOGRAPHS
Tetraonchinae. Average diameter of pharynx 0.027 mm. (0.024- 0.039 mm.).
Systematic position.—This species occurs in mixed infestations with Cleidodiscus robustus Mueller, 1934, Haplocleidus dispar (Mueller, 1936), Pterocleidus acer (Mueller, 1936) and Actinocleidus fergusoni n. sp. on the bluegill sunfish. Superficially the copulatory complex is similar to that of H. dispar. Each bar of O. mucronatus possesses a spine on the posterior middle region, a condition seldom found in the genus. Specimens of O. mucronatus from Lake Senachwine were almost twice the size of those from the same host, viz., the bluegill sunfish, from Lake Decatur. One hundred per cent infestation with this parasite is recorded for: nineteen bluegills from Lake Chautauqua, Havana, IIL, in May, 1936; five hybrids between the bluegill and pumpkinseed sunfishes from Lake Senachwine, Henry, Hl., in June, 1936; six hybrids between the orange-spotted and pumpkinseed sunfishes from Lake Senachwine, Henry, Ill., in June, 1936; four orange-spotted sunfish from the Salt Fork of the Big Vermilion River, Homer, Ill, in April, 1936; and one bluegill sunfish from the Illinois State Natural History Survey pond, Urbana, Il., in July, 1936. Twelve bluegills from Lake Senachwine in June, 1936, were infested seventy-five per cent.
Onchocleidus distinctus Mizelle, 1936 Figs. 8, 109-117 Host and Locality: Long-eared Sunfish (Xenotis megalotis), Embarrass River, Urbana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9086.
General anatomy.—Relatively small parasites devoid of body scales and internal spicules. Average length 0.476 mm. (0.344-0.590 mm.), average width at level of cephalic lobes 0.065 mm. (0.048-0.072 mm.), greatest body width average 0.070 mm. (0.050-0.095 mm.), average width of peduncle at junction with haptor 0.046 mm. (0.032-0.057 mm.). Haptor distinct, hexagonal or pentagonal in shape and broader than long, average width 0.078 mm. (0.0640.110 mm.), average length 0.070 mm. (0.057-0.086 mm.). Ventral bar slightly shorter than dorsal bar. Average length of ventral bar 0.024 mm. (0.021-0.027 mm.), average length of dorsal bar 0.026 mm. (0.023-0.029 mm.). Anchors similar in shape, bases slightly bifurcate, superficial roots longer than deep roots. Anchor wings weakly developed. Distal portion of each anchor shait slightly dilated and hollow. Internal angle at junction of each anchor shaft and point. Ventral anchors slightly longer than dorsal anchors. Average length of ventral anchors 0.035 mm. (0.032-0.038 mm.), average width
STUDIES ON TREMATODES—MIZELLE 39
0.016 mm. (0.013-0.019 mm.), average length of dorsal anchors, 0.034 mm. (0.030-0.036 mm.), average width 0.013 mm. (0.011-0.015 mm.). Bases of ventral anchors not conspicuously wider than bases of the dorsal anchors. Each of the fourteen hooks consists of an elongate cylindrical body with a sickle-shaped termination and opposable piece distally. Body of each hook of pair number five, which lies between the shafts of ventral anchors, shows a tendency toward differentiation into a base and shaft. Hooks of pairs numbers one, six, and seven possess hollow bodies, hooks of pair number two often have slightly hollow bodies, rest of hook bodies solid. Hooks of pair number one larger and hooks of pair number five conspicuously smaller than rest of hooks. The arrangement of the hooks is as given in the general morphology ot the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mim Range in mm. 1 0.032 0.027-0.036 2 0.026 0.023-0.030 3 0.026 0.023-0.029 4 0.028 0.023-0.030 5 0.010 0.009-0.012 6 0.029 0.025-0.032 if 0.030 0.027-0.034
Anterior eye spots smaller and almost invariably farther apart than members of posterior pair.
Reproductive system.—Gonads located anteriorly in the posterior body half, testis ovate, smaller than ovary and situated posterior to it. The vas deferens arises from anterior end of testis, passes forward on left side of body and expands into a fusiform seminal vesicle near cirrus base. Two prostate glands present, each tubular in shape, smaller one about three-fourths the size of larger, and filled with a finely granular colorless fluid, larger one containing a coarsely granular yellowish fluid. Copulatory complex weakly developed and situated in a relatively small vestibule. Cirrus a small chitinous tube with a cirral thread around the shaft. Accessory piece a partial sleeve, open proximally and complete distally, and enclosing cirrus. Contractile elements arise on inner surface of accessory piece and insert on base of cirrus. On contraction of these structures the accessory piece remains i situ, and the cirrus is projected ventrally through the vestibular pore, for a short distance beyond the body surface. Retraction of the cirrus not understood.
Ovary ovate, larger than testis and situated anterior to it. Egg pore on ventral surface near vestibular pore. Vagina on right margin near termination of first body half; vaginal canal a chitinized tube emptying
40 ILLINOIS BIOLOGICAL MONOGRAPHS
mesially into a small seminal receptacle. Vitellaria and vitelline ducts are as described in the general morphology of the North American fresh- water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—The digestive system is as described in the general morphology of the North American fresh-water Tetraon- chinae. Average diameter of pharynx 0.023 mm. (0.019-0.028 mm.). The excretory system is common to the North American fresh-water Tetra- onchinae. Two especially large solenocytes are present immediately an- terior to the level of the ovary; a third flame cell is present in the region of the seminal receptacle.
Systematic position.—This parasite occurs in mixed infestations with Cleidodiscus bedardi Mizelle, 1936, Actinocleidus articularis (Mizelle, 1936), Pterocleidus acuminatus (Mizelle, 1936), an undescribed species of the genus Cleidodiscus Mueller, 1934, and an undescribed species of Haplocleidus Mueller, 1937. It has been recovered only from the long- eared sunfish. The cirrus superficially resembles the cirrus of Oncho- cleidus mimus Mueller, 1936. The accessory piece is wanting in O. mimus but is present in Onchocleidus distinctus. The vaginal canal, bars, and slightly dilated and hollow anchors, are conspicuously different from any other described member of the genus. One hundred per cent infestation is recorded for one hundred twenty-five hosts taken from the Em- barrass River during the months of April, May, June, July, and August, 1936.
Onchocleidus cyanellus sp. nov. Figs. 135-140 Host and Locality: Green Sunfish (Apomotis cyanellus), Embarrass River, Urbana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9142.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.572 mm. (0.328-0.738 mm.), greatest body width average 0.096 mm. (0.067-0.114 mm.). Haptor distinct, hexagonal in shape and broader than long. Each bar possesses a spine projecting from middle of posterior margin. Average length of ventral bar 0.024 mm. (0.021-0.027 mm.), average length of dorsal bar 0.025 mm. (0.021-0.029 mm.). Wings on anchor shafts deli- cate. Anchors similar in shape, bases slightly bifurcate, superficial roots noticeably longer than deep roots. Anchor shafts solid and unite with anchor points to form an internal angle at junction. Anchors approxi- mately same size. Average length of ventral anchors 0.052 mm. (0.048- 0.057 mm.), average length of dorsal anchors 0.053 mm. (0.049-0.059). Each hook has an elongate chitinous body with a sickle-shaped termi-
STUDIES ON TREMATODES—MIZELLE 41
nation and opposable piece distally. Hooks of pair number five show a tendency toward differentiation into a base, shaft, sickle-shaped termi- nation and opposable piece. Length of hooks of pair number five 0.008- 0.013 mm., length of rest of hooks 0.024-0.032 mm. The arrangement of the hooks is as given in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62). Anterior eye spots smaller and usually farther apart than members of the posterior pair.
Reproductive system.—Gonads located in posterior half of body; vas deferens passes forward as a slightly undulant tube. Copulatory complex weakly developed and enclosed within a slender vestibule. Cirrus a chitin- ous tube with a cirral thread around the shaft, length 0.035 mm. (0.032- 0.040 mm.) ; accessory piece vestigial. Operation of cirrus not observed.
Ovary subspherical; egg pore on ventral surface near vestibular pore. Vagina on right body margin near midlength. Vitellaria and vitelline ducts as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—Digestive and excretory systems are as given in the general morphology of the North American fresh- water Tetraonchinae. Average diameter of pharynx 0.024 mm. (0.018- 0.036 mm.).
Systematic position.—This species occurs in mixed infestations with Cleidodiscus diversus n. sp., Cleidodiscus robustus Mueller, 1934, Actin- ocleidus longus n. sp., and an undescribed member of the genus Actin- ocleidus Mueller, 1937. The anchors and bars resemble those of Onchocleidus mucronatus Mizelle, 1936. The copulatory complex is different from the foregoing species and the zigzag vaginal tube charac- teristic of O. mucronatus is wanting. One hundred per cent infestation
is recorded for twenty-six green sunfish from the Embarrass River in May, 1937.
Genus Actinocleidus Mueller, 1937
Diagnosis —Tetraonchinae with intestine bifurcate but confluent pos- teriorly. Vagina present on left body margin near the midlength. Copu- latory complex consisting of a cirrus and accessory piece. Accessory piece well developed, always present, and articulated to the cirrus base. Haptor distinct, discoidal in shape, and has both pairs of anchors on the ventral surface. The bars connecting the anchor bases are articu- lated with each other in their midregions. Each of the fourteen hooks present is differentiated into a base, shaft, sickle-shaped termination and opposable piece. Parasitic on the gills of fresh-water fishes. Type species, Actinocleidus oculatus (Mueller, 1934).
42 ILLINOIS BIOLOGICAL MONOGRAPHS
Actinocleidus articularis (Mizelle, 1936) Figs. 10, 40-48 Host and Locality: Long-eared Sunfish (NXenotis megalotis), Embarrass River, Urbana, Illinois. Location: Gills. Specimen: U.S.N.M. Helm. Coll. No. 9084.
General anatomy.—Relatively small gill parasites with internal spicules and surface scales wanting. Average length 0.470 mm. (0.360- 0.615 mm.), average width at level of cephalic lobes 0.062 mm. (0.049- 0.082 mm.), greatest body width average 0.068 mm. (0.049-0.079 mm.), average width of peduncle at junction with haptor 0.041 mm. (0.028- 0.067 mm.). Haptor distinct, disc-like in shape and broader than long, average width 0.072 mm. (0.061-0.086 mm.), average length 0.055 mm. (0.047-0.057 mm.). Anterior bar noticeably bent posteriorly in mid- portion with a notch present near each end on posterior margin. Pos- terior bar modified to form a plate-like structure, anterior end of which articulates with posterior surface of anterior bar. Average length of anterior bar 0.037 mm. (0.032-0.042 mm.), average length of posterior bar 0.022 mm. (0.019-0.025 mm.). Anchors similar in shape and size, bases nonbifurcate, deep roots vestigial. Anchor wings moderately de- veloped. Anchor shafts solid and regularly recurved without formation of an angle at junction with hollow points. Average length of anterior an- chors 0.033 mm. (0.032-0.038 mm.), average width 0.010 mm. (0.009- 0.013 mm.), average length of posterior anchors 0.032 mm. (0.028-0.038 mm.), average width 0.010 mm. (0.008-0.011 mm.). Bases of hooks sub- spherical in shape and very short as compared with shafts. Hooks of pair number one slightly shorter than rest of hooks. Arrangement of the hooks is as described in the general morphology of the North American fresh-water Tetraonchinae with fourteen haptoral hooks (See pages 9, 15, and 62).
Hook pair Average length in mm. Range in mm. 1 0.011 0.009-0.015 2 0.014 0.013-0.015 3 0.015 0.013-0.019 4 0.015 0.013-0.017 5 0.014 0.013-0.015 6 0.015 0.013-0.019 7 0.014 0.013-0.015
Anterior eye spots smaller and usually farther apart than members of the posterior pair.
Reproductive system.—Gonads situated in posterior half of body, testis ovate, about same size as ovary and located dorsoposterior to it.
STUDIES ON TREMATODES—MIZELLE 43
Vas deferens arises from anterior end of testis and passes forward as an undulant tube and dilates slightly to form a tubular seminal vesicle near cirrus base. Two prostate glands present, smaller one somewhat bulbular in shape and filled with a finely granular colorless fluid, larger one bulbular in shape and containing a coarsely granular yellowish fluid. Copulatory complex well developed and situated in a moderate-sized vestibule. Cirrus a chitinous tube with a large base and a doubly re- curved shaft which ends in a forked termination. Accessory piece a chitinous structure of an aviform shape. Operation of copulatory com- plex not observed.
Ovary ovate in outline, about same size as testis and located antero- ventrally to it. Egg pore located on ventral surface on right of copula- tory complex. Vagina present on left margin near midlength of body; vaginal canal a short chitinous tube emptying into a transparent seminal receptacle which lies at anterior end of ovary. Vitellaria and vitelline ducts as described in the general morphology of North American fresh- water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American fresh-water
Tetraonchinae. Average diameter of pharynx 0.025 mm. (0.021- 0.028 mm.).
Systematic position—This species, from Illinois localities, occurs in mixed infestations with Onchocleidus distinctus Mizelle, 1936, Cleido- discus bedardi Mizelle, 1936, Pterocleidus acuminatus (Mizelle, 1936), an undescribed species of Cleidodiscus Mueller, 1934, and an undescribed species of the genus Haplocieidus Mueller, 1937. Actinocleidus oculatus (Mueller, 1934), structurally stands closer to this species than does any other member of the genus. Actinocleidus articularis is readily dis- tinguishable from A. oculatus by the presence of hollow anchor points, a doubly recurved cirrus, and an aviform accessory piece. The former species has been taken only from the long-eared sunfish, whereas the latter is common only to the pumpkinseed sunfish (Eupomotis gibbosus). One hundred twenty-five long-eared sunfish taken from the Embarrass River south of Urbana, IIl., in the months of April, May, June, July, and August, 1936, were infested one hundred per cent with this parasite.
Actinocleidus longus sp. nov. Figs. 166-172 Host and Localities: Green Sunfish (Apomotis cyanellus), Embarrass River, Urbana, Ill.; Boomer Creek, Stillwater, Okla. Location: Gills. Specimen: U.S.N.M. Helm. Coll. No. 9140.
44 ILLINOIS BIOLOGICAL MONOGRAPHS
General anatomy.—Relatively small gill parasites with internal spicules and surface scales wanting. Average length 0.444 mm. (0.336-0.573 mm.), greatest body width average 0.069 mm. (0.055-0.095 mm.). Haptor distinct, disc-like in shape and broader than long. Anterior bar noticeably bent posteriorly in midportion, and articulated with central portion of posterior bar. Average length of anterior bar 0.044 mm. (0.036-0.049 mm.), average length of posterior bar 0.031 mm. (0.027-0.040 mm.). Anchors similar in shape and size, bases nonbifurcate, deep roots vestigial. Anchor wings well developed. Anchor shafts hollow and regularly re- curved without formation of an angle at junction with hollow points. Average length of anterior anchors 0.036 mm. (0.034-0.038 mm.), aver- age length of posterior anchors 0.037 mm. (0.032-0.042 mm.). Bases of hooks subspherical in shape and very short as compared with shafts, hook lengths 0.013-0.017 mm. Arrangement of the hooks is as described in the general morphology of the North American fresh-water Tetraonchinae with fourteen haptoral hooks (see pages 9, 15, and 62). Anterior eye spots smaller and usually farther apart than members of the posterior pair.
Reproductive system.—Gonads situated in posterior half of body; vas deferens arises from anterior end of testis and passes forward as an undulant tube. Copulatory complex well developed and situated in a moderate-sized vestibule. Cirrus a chitinous tube with a moderately large base, and attenuated to form a hair-like tube in the middle, but moderately enlarged distally. Accessory piece whip-like and much shorter than the cirrus. Operation of copulatory complex not observed.
Ovary ovate in outline; egg pore located on ventral surface near vestibular pore. Vagina present on left margin near midlength of body. Vitellaria and vitelline ducts as described in the general morphology of North American fresh-water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American fresh-water
Tetraonchinae. Average diameter of pharynx 0.026 mm. (0.021- 0.029 mm.).
Systematic position.—This species occurs in mixed infestations with Cleidodiscus diversus n. sp., Cleidodiscus robustus Mueller, 1934, Onchocleidus cyanellus n. sp., and an undescribed species of Actinocleidus Mueller, 1937. This species has been collected only from the green sunfish. It possesses a copulatory complex somewhat similar to that of Cleidodiscus longus Mizelle, 1936, from the white crappie, and anchors, hooks, and bars resembling those of Actinocleidus articularis (Miczelle, 1936). One hundred per cent infestation with this parasite is recorded for twenty-six green sunfish from the Embarrass River in May, 1937.
STUDIES ON TREMATODES—MIZELLE 45
Actinocleidus fergusoni sp. nov. Figs. 148-153 Host and Localities: Bluegill Sunfish (Helioperca macrochira), Lake Senachwine, Henry, Ill.; Boomer Creek, Stillwater, Okla.
Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9141.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.379 mm. (0.330-0.444 mm.), greatest body width average 0.056 mm. (0.045-0.083 mm.). Haptor distinct, subdiscoidal in shape and broader than long. Anterior bar bent posteriorly in the middle; posterior bar modified to articulate with anterior bar. Average length of anterior bar 0.029 mm. (0.025-0.033 mm.), average length of posterior bar 0.019 mm. (0.012-0.025 mm.). Anchors similar in shape, nonbifurcate, superficial roots elongate, deep roots vestigial, Anchor shafts hollow and regularly recurved without formation of angle at junction with hollow points. Anchors similar in size and shape. Average length of anterior anchors 0.025 mm. (0.023- 0.027 mm.), average length of posterior anchors 0.023 mm. (0.021-0.025 mm.). Hooks not conspicuously different in length. Hook lengths 0.009- 0.015 mm. Hook bases subspherical and much shorter than hook shafts. The arrangement of hooks as described in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62). Anterior eye spots smaller and generally farther apart than members of the posterior pair.
Reproductive system.—Gonads located in posterior body half, testis ovate, situated dorsoposterior to and about same size as ovary. Vas deferens passes forward as a slightly undulant tube. Copulatory complex well developed and situated in a moderately large vestibule. Cirrus a simple curved chitinous tube with large base, and tapered distally to a fine point, average length 0.023 mm. (0.021-0.028 mm.). Accessory piece with two curves and with a knob near the middle. Operation of cirrus not observed.
Ovary subspherical, and situated anteroventrally to testis. Egg pore on ventral surface on right of copulatory complex. Vagina present on left margin near midlength of body. Vitellaria and vitelline ducts exist as described in the general morphology of the North American fresh- water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—The digestive and excretory sys- tems are as described in the general morphology of the North American
fresh-water Tetraonchinae. Average diameter of pharynx 0.017 mm. (0.012-0.025 mm.).
Systematic position.—This parasite, from Illinois localities, occurs in
46 ILLINOIS BIOLOGICAL MONOGRAPHS
mixed infestations with Cleidodiscus robustus Mueller, 1934, Onchocleidus mucronatus Mizelle, 1936, Pterocleidus acer (Mueller, 1936) and Haplocleidus dispar (Mueller, 1936). This species is closely related to Actinocleidus gracilis Mueller, 1937. The cirrus of Actinocleidus fergusoni is sickle-shaped whereas the cirrus of A. gracilis is an undu- lant tube. Only slight infestation of the bluegill sunfish is recorded for this parasite. Genus Pterocleidus Mueller, 1937
Diagnosis —Tetraonchinae with intestine bifurcate but confluent posteriorly. The vagina, when present, is located on the right body margin near the midlength. Copulatory complex consisting of a cirrus, cirral thread, and accessory piece or a cirrus and cirral fin. The accessory piece, when present is never articulated with the cirrus base. Haptor distinct, pentagonal or hexagonal in shape. Each anchor shaft possesses a spur-like projection near the origin of the anchor point. The bars con- necting the anchor bases are not articulated with each other. Each haptoral hook generally consists of a solid or hollow shaft terminating distally in a sickle-shaped structure and opposable piece. Parasitic on the gills of fresh-water fishes. Type species Pterocleidus acer (Mueller, 1936).
Pterocleidus acuminatus (Mizelle, 1936) Figs. 11, 94-102 Host and Locality: Long-Eared Sunfish (NXenotis megalotis), Embarrass River, Urbana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9089.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.495 mm. (0.338-0.640 mm.), average width at level of cephalic lobes 0.066 mm. (0.052-0.095 mm.), greatest body width average 0.093 mm. (0.066-0.118 mm.), average width of peduncle at junction with haptor 0.053 mm. (0.038-0.068 mm.). Haptor distinct, hexagonal or pentagonal in shape and slightly broader than long, average width 0.078 mm. (0.064-0.104 mm.), average length 0.077 mm. (0.068-0.098 mm.). Ventral bar smaller than dorsal bar, both bars with a gentle posterior slope in the midregions. Average length of ventral bar 0.025 mm. (0.019-0.027 mm.), average length of dorsal bar 0.026 mm. (0.022-0.029 mm.). Anchors similar in size and shape, bases slightly bifurcate, superficial roots longer than deep roots. Anchor shafts solid, junction with points forms an internal angle. Spurs on anchor shafts well developed. Anchor wings clearly discernible. Average length of ventral anchors 0.047 mm. (0.040-0.051 mm.), average width 0.014 mm, (0.011-0.017 mm.), average length of dorsal anchors 0.048 mm.
STUDIES ON TREMATODES—MIZELLE 47
(0.040-0.053 mm.), average width 0.013 mm. (0.010-0.017 mm.). Each hook consists of an elongate, solid chitinous body with a sickle-shaped termination and opposable piece distally. Hooks of pairs numbers one, six, and seven larger and pair number five noticeably smaller than rest of hooks. The arrangement of the hooks is as given in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range in mim. 1 0.026 0.021-0.029 2 0.020 0.015-0.023 3 0.022 0.015-0.025 4 0.025 0.019-0.029 5 0.012 0.009-0.015 6 0.026 0.020-0.029 7 0.027 0.023-0.029
Anterior eye spots smaller and almost invariably farther apart than members of the posterior pair.
Reproductive system.—Gonads located anteriorly in posterior body half, testis ovate, posterior to, and about same size as ovary. Vas deferens passes forward on left side of body and dilates to produce a spindle- shaped seminal vesicle immediately posterior to cirrus base. Two prostate glands present, banana-shaped, and about of equal size. One of the prostate glands contains a finely granular colorless hyaline fluid, the other contains a coarsely granular yellowish fluid. Each prostate gland empties into cirrus base by a single individual duct. Copulatory complex weakly developed and enclosed within a slender vestibule. Cirrus a cork- screw-like chitinous tube with a moderate-sized base. Accessory piece a ploughshare-shaped structure lying along side of cirrus proximally and complete distally to form a ring through which the cirrus passes. Opera- tion of cirrus not observed.
Ovary ovate, about size of testis and situated anterior to it. Egg pore located on ventral surface near vestibular pore. Vagina present on right body margin near midlength; vaginal canal a chitinized tube often making one or two loops before emptying mesially into the seminal receptacle. Vitellaria and vitelline ducts as described in the general morphology of the North American fresh-water Tetraonchinae. Shell gland not observed.
Digestive and excretory systems.—The digestive and excretory sys- tems exist as described for the North American fresh-water Tetra- onchinae. Average diameter of pharynx 0.026 mm. (0.019-0.030 mm.). Two large flame cells present, one at level of seminal receptacle, the other one at level of copulatory complex.
48 ILLINOIS BIOLOGICAL MONOGRAPHS
Systematic position.—This species occurs in mixed infestations with Cleidodiscus bedardi Mizelle, 1936, Actinocleidus articularis (Mizelle, 1936), Onchocleidus distinctus Mizelle, 1936, and an undescribed mem- ber of Haplocleidus Mueller, 1937, and undescribed member of Cleidodi- scus Mueller, 1934. The cirrus of Pterocleidus acuminatus resembles that of Onchocleidus principalis Mizelle, 1936, but the anchors possess spur- like structures which are characteristic of the genus Pterocleidus. P. acu- munatus has been collected only from the long-eared sunfish. The bars, anchors, vagina and vaginal tube of this species are distinctive in them- selves. One hundred twenty-five hosts from the Embarrass River in April, May, June, July, and August, 1936, were infested one hundred per cent with this parasite.
Genus Urocleidus Mueller, 1934
Diagnosis.—Tetraonchinae with intestine bifurcate but confluent posteriorly. Vagina and seminal receptacle lacking. Copulatory complex weakly developed and consisting of an accessory piece and cirrus. Acces- sory piece not articulated to cirrus base. Haptor subdiscoidal, pentagonal, or hexagonal in shape. Each of the fourteen hooks present may be solid or hollow, with a sickle-shaped structure and opposable piece distally ; or consist of a base, shaft, sickle-shaped structure, and opposable piece. Parasitic on the gills of fresh-water fishes. Type species Urocleidus aculeatus (Van Cleave and Mueller, 1932).
Urocleidus umbraensis sp. nov. Figs. 159-165 Host and Locality: Top Minnow (Fundulus mnotatus), Embarrass River, Urbana, III. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9146.
General anatomy.—Relatively small parasites devoid of surface scales and internal spicules. Average length 0.546 mm. (0.508-0.623 mm.), greatest body width average 0.123 mm. (0.090-0.140 mm.). Haptor dis- tinct, subdiscoidal to hexagonal in shape and broadly connected to the short peduncle. Ventral bar variable in shape, length 0.025 mm. (0.023- 0.027 mm.), average length of dorsal bar 0.023 mm. (0.021-0.026 mm.). Anchors similar in shape, bases slightly bifurcate, superficial roots longer than deep roots, wings clearly evident. Each anchor shaft with a small cavity proximally, regularly recurved without formation of angle at junction with points. Bases of ventral anchors wider than dorsal anchor bases. Average length of ventral anchors 0.023 mm. (0.021-0.025 mm.), average length of dorsal anchors 0.022 mm. 0.019-0.024 mm.). Each hook
STUDIES ON TREMATODES—MIZELLE 49
consists of a slender shaft, sickle-shaped termination and opposable piece. Hook lengths 0.010-0.013 mm. The arrangement of the hooks is as de- scribed for the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62). Anterior eye spots smaller and farther apart than members of the posterior pair.
Reproductive system.—Gonads situated anteriorly in posterior body half ; vas deferens passes forward as a slightly undulant tube. Copulatory complex weakly developed and situated in a small vestibule. Cirrus a curved chitinous tube, tapered distally, length 0.025 mm. (0.019-0.030 mm.). Accessory piece a chitinous structure of variable shape. Operation of copulatory complex not observed.
Egg pore on ventral surface anterior to base of copulatory complex. Vagina and seminal receptacle lacking. Vitellaria and vitelline ducts exist as described in the general morphology of the North American fresh-water Tetraonchinae. Nature of shell gland not determined.
Digestive and excretory systems.—The digestive and excretory sys- tems are as given in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.032 mm.
(0.029-0.038 mm.).
Systematic position.—This species has been collected only from the gills of Fundulus notatus and is the only monogenetic fluke recorded for this host. Urocleidus wmbraensis multiplies readily on hosts confined in aquaria. Hosts from natural waters present a low infestation with this parasite.
Genus Dactylogyrus Diesing, 1850 Synonym: Gyrodactylus Monticelli, 1892, in part.
Diagnosis.—Dactylogyridae with intestine bifurcate but usually con- fluent posteriorly. Vagina present or absent. Copulatory complex well developed. Haptor moderately developed. One pair of anchors present with bases connected by one or two chitinous bars. Fourteen hooks present on haptor. Four eye spots of approximately the same size in head region. Parasitic on the gills of fishes. Type species, Dactylogyrus auriculatus (v. Nordmann, 1832) Diesing, 1850.
Dactylogyrus bychowskyi Mizelle, 1937 Figs. 118-122 Host and Localities: Blunt-Nosed Minnow (Hyborhynchus notatus), Embarrass River and Drainage Ditch, Urbana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9143.
General anatomy.—Relatively small gill trematodes of a somewhat
50 ILLINOIS BIOLOGICAL MONOGRAPHS
fusiform nature. Average length 0.381 mm. (0.285-0.615 mm.), average width at level of cephalic lobes 0.057 mm. (0.040-0.086 mm.), greatest body width average 0.079 mm. (0.049-0.108 mm.), average width of peduncle at junction with haptor 0.044 mm. (0.030-0.067 mm.). Haptor distinct, knob-like, at times assuming a subpentagonal shape and broader than long; average width 0.072 mm. (0.050-0.095 mm.), average length 0.059 mm. (0.048-0.068 mm.). The single pair of anchors is located dorsally with their superficial bases connected by a solid chitinous bar. Bases of anchors bifurcate, superficial root noticeably longer than deep root. Anchor shafts (solid in fresh preparations, small cavity in per- manent mounts) make junction with points to form a distinct internal angle. Wings on anchor shafts clearly visible. Average length of anchors 0.048 mm. (0.038-0.057 mm.), average width of anchor bases 0.020 mm. 0.015-0.028 mm.). A ventral bar or “ventrales Chitinstuck” or “Chitin- klammer” of German workers, has not been observed in this species. Average length of dorsal bar 0.021 mm. (0.017-0.025 mm.). Each of the fourteen hooks present is differentiated into a base, shaft, sickle-shaped termination and opposable piece. Hook bases ovate and very short as compared with length of shaits. Hooks of pairs numbers one and five slightly shorter than rest of hooks. The arrangement of the hooks is as given in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15,
and 62).
Hook pair Average length in mm. Range in mim. 1 0.015 0.013-0.017 2 0.017 0.015-0.019 3 0.017 0.015-0.019 4 0.018 0.015-0.021 5 0.014 0.011-0.017 6 0.017 0.013-0.021 7 0.017 0.015-0.019
Eye spots four in number, approximately equal in size and with members of each pair about the same distance apart.
Reproductive system.—Gonads located near middle of body, testis ovate, situated dorsoposterior to and smaller than ovary. Vas deferens passes forward near the median line of the body as a slightly undulant tube. Seminal vesicle lies near the copulatory complex base and consists of an elongate dilatation of the vas deferens. Two prostate glands present near copulatory compiex base, one bulbular in shape, the other botuliform, each emptying into cirrus base by a single individual duct. Copulatory complex well developed and situated in a relatively large vestibule. Cirrus an elongate hollow chitinous tube tapering to a point distally and with a digitiform projection arising from the base. Average length of cirrus
STUDIES ON TREMATODES—MIZELLE iL
wm
0.044 mm. (0.038-0.051.). Accessory piece a solid chitinous blade-like structure with a knob present about halt-way its length. Proximal portion of accessory piece articulated with base of cirrus.
Ovary ovate, larger than testis and with spatial relationships as given above. Egg pore located on ventral surtace in the region of the copula- tory complex. Vagina present on right body margin in posterior portion of anterior body half. Vaginal tube chitinous and connected with a small clear ovate seminal receptacle. Vitellaria and vitelline ducts as given in the general morphology of the North American fresh-water Tetraonchinae.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.038 mm. (0.029- 0.048 mm.).
Systematic position.—Dactylogyrus bychowskyi possesses a copulatory apparatus similar to that of Dactylogyrus amphibothrium Wagener, 1857, but is different from the latter species in the possession of a digitiform process on the cirrus base. The anchors, hooks, and bars of the two species differ in shape and size relationships. D. amphibothriwm is found on Acerina cernua whereas D. bychowskyi occurs on Hyborhynchus notatus.
Dactylogyrus bifurcatus Mizelle, 1937 Figs. 123-128 Host and Localities: Blunt-Nosed Minnow (Hybdorhynchus notatus), Embarrass River and Drainage Ditch, Urbana, III. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9144.
General anatomy.—Relatively small gill trematodes of a somewhat fusiform nature. Average length 0.343 mm. (0.254-0.492 mm.), average width at level of cephalic lobes 0.051 mm. (0.038-0.065 mm.), greatest body width average 0.070 mm. (0.049-0.095 mm.), average width of peduncle at junction with haptor 0.038 mm. (0.019-0.042 mm.). Haptor distinct, subdiscoidal in shape and broader than long, average width 0.062 mm. (0.049-0.087 mm.), average length 0.044 mm. (0.023-0.057 mm.). The single pair of anchors is located dorsally with their super- ficial bases connected by a solid chitinous bar. Bases of anchors bifurcate, superficial root longer than deep root. Anchor shafts (solid in fresh preparations, small cavity in permanent mounts) regularly recurved without formation of an angle at junction of shafts and anchors. Wings on anchor shafts clearly visible. Average length of anchors 0.033 mm. (0.028-0.034 mm.), average width of anchor bases 0.012 mm. (0.008- 0.013 mm.). Ends of ventral bar slightly bent posteriorly with a short median projection on anterior border and about the same length as dorsal
92 ILLINOIS BIOLOGICAL MONOGRAPHS
bar. Average length of dorsal bar 0.017 mm. (0.015-0.023 mm.). Each of the fourteen hooks present is differentiated into a base, shaft, sickle- shaped termination and opposable piece. Hook bases elongate and nearly as long as the shafts. Hooks of pair number one slightly shorter than the rest of the hooks. The arrangement of the hooks is as given in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range in mm. 1 0.016 0.013-0.019 2 0.018 0.015-0.021 3 0.019 0.015-0.023 + 0.018 0.015-0.021 a 0.017 0.015-0.019 6 0.018 0.013-0.019 7 0.017 0.015-0.019
Eye spots four in number, about the same size and with members of the two pairs about the same distance apart.
Reproductive system.—Gonads situated near middle of body, testis globular, located posterior to and much larger than ovary. Vas deferens passes forward near median line of body as a slightly undulant tube. Seminal vesicle near copulatory complex and consists of an elongate dilatation of vas deferens. The single prostate gland which lies near the copulatory complex base is bulbular in shape. Copulatory complex well developed and situated in a small vestibule. Cirrus a short curved chitinous tube tapering to a point distally. Average length of cirrus 0.029 mm. (0.027-0.030 mm.). Accessory piece a solid chitinous structure bifurcate distally and with the proximal portion articulated to cirrus base.
Ovary ovate, smaller than testis and with spatial relationships as given above. Egg pore located on ventral surface in region of copulatory complex. The vagina and seminal receptacle have not been observed in this species. Vitellaria and vitelline ducts as given in the general morphology of the North American fresh-water Tetraonchinae.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.022 mm. (0.019- 0.027 mm.).
Systematic position—The morphology of Dactylogyrus bifurcatus conforms with the general generic morphology, but differs from other members of the genus by the possession of a short distally bifurcate accessory piece.
STUDIES ON TREMATODES—MIZELLE 53
Dactylogyrus simplex Mizelle, 1937 Figs. 129-134 Host and Localities: Blunt-Nosed Minnow (Hyborhynchus notatus), Embarrass River and Drainage Ditch, Urbana, III. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9145.
General anatomy.—Relatively small gill trematodes of a general fusi- form shape. Average length 0.324 mm. (0.189-0.443 mm.), average width at level of the cephalic lobes 0.045 mm. (0.038-0.057 mm.), greatest body width average 0.062 mm. (0.044-0.076 mm.), average width of peduncle at junction with haptor 0.036 mm. (0.023-0.048 mm.). Haptor distinct, irregularly discoidal in shape, and broader than long, average width about 0.056 mm. (0.042-0.074 mm.), average length about 0.038 mm. (0.029-0.048 mm.). The single pair of anchors is located dorsally with their superficial bases connected by a solid chitinous bar. Bases of anchors bifurcate, superficial root longer than deep root. Anchor shafts solid and regularly recurved without formation of an angle at junction of shafts and points. Wings on anchor shafts clearly discernible. Average length of anchors 0.028 mm. (0.027-0.034 mm.), average width of anchor bases 0.012 mm. (0.008-0.017 mm.). Ends of ventral bar bent posteriorly with a short median projection on the anterior border and about same length as dorsal bar. Average length of dorsal bar 0.019 mm. (0.017- 0.021 mm.). Each of the fourteen hooks present is differentiated into a base, shaft, sickle-shaped termination, and opposable piece. Hook bases elongate and nearly as long as the shafts. Hooks of pair number one slightly shorter than rest of hooks. The arrangement of the hooks is as given in the general morphology of the North American fresh-water
Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62).
Hook pair Average length in mm. Range in mm. 1 0.015 0.011-0.017 Zz 0.017 0.015-0.019 a 0.018 0.015-0.023 4 0.017 0.015-0.023 5 0.016 0.011-0.021 6 0.016 0.013-0.017 7 0.017 0.014-0.023
Eye spots four in number, approximately equal in size and with members of each pair about the same distance apart.
Reproductive system.—Gonads situated in first portion of posterior body half. Testis globular, located posterior to and much larger than ovary. Vas deferens passes forward near median line of body as a slightly undulant tube. Seminal vesicle lies near copulatory complex and
54 ILLINOIS BIOLOGICAL MONOGRAPHS
consists of a dilatation of vas deferens. Two prostate glands present near copulatory complex base, one bulbular in shape, the other elongate, each emptying into cirrus base by a single individual duct. Copulatory complex well developed and situated in a large vestibule. Cirrus a hollow, sickle- shaped, chitinous tube, tapering to a point distally. Average length of cirrus 0.024 mm. (0.019-0.029 mm.). Accessory piece a solid chitinous structure with a knob present near the midlength. The proximal portion of the accessory piece is articulated with the base of the cirrus.
Ovary ovate, smaller than testis and with spatial relationships as given above. Egg pore located on ventral surface in region of copulatory complex. The vagina and seminal receptacle are not clearly discernible in this form. Vitellaria and vitelline ducts as given in the general morphology of the North American fresh-water Tetraonchinae.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American fresh-water Tetraonchinae. Average diameter of pharynx 0.022 mm. (0.019- 0.025 mm.).
Systematic position —Dactylogyrus simplex is closely related morpho- logically to Dactylogyrus anchoratus (Dujardin, 1845); Dactylogyrus intermedius Wegener, 1909; and Dactylogyrus macracanthus Wegener, 1909. Dactylogyrus simplex differs from these three related species in the shape and size relationships of the copulatory complex, anchors, bars, and hooks. D. anchoratus occurs on Carassius carassius, Carassius auratus, and Cyprinus carpio; D. intermedius on Carassius carassius; D. macra- canthus on Tinca tinca; and D. simplex on Hyborhynchus notatus.
Dactylogyrus atromaculatus sp. nov. Figs. 154-158 Host and Locality: Creek Chub (Semotilus atromaculatus), Embarrass River, Urbana, Ill. Location: Gills. Specimens: U.S.N.M. Helm. Coll. No. 9148.
General anatomy.—Relatively small gill trematodes of a somewhat fusiform nature. Average length 0.526 mm. (0.385-0.656 mm.), greatest body width average 0.089 mm. (0.080-0.103 mm.). Haptor hexagonal or subdiscoidal, and well set off from the body. The single pair of anchors is located dorsally with their superficial bases connected by a solid chitinous bar. Bases of anchors bifurcate, superficial root noticeably longer than deep root. Anchor shafts solid and regularly recurved with- out formation of internal angle at junction with points. Wings on anchor shafts clearly visible. Average length of anchors 0.033 mm. (0.029- 0.040 mm.). A ventral bar, “ventrales Chitinstiick” or “Chitinklammer” of German workers, has not been observed for this species. Length of
STUDIES ON TREMATODES—MIZELLE 55
dorsal bar about length of anchors. Each of the fourteen hooks present is differentiated into a base, shaft, sickle-shaped termination and oppos- able piece. Hook bases elongate-ovate and shorter than the shaits. Hooks similar in shape and size, lengths 0.017-0.025 mm. The arrangement of the hooks is as given in the general morphology of the North American fresh-water Tetraonchinae possessing fourteen haptoral hooks (see pages 9, 15, and 62). Eye spots four in number, approximately equal in size and with members of each pair about the same distance apart.
Reproductive system.—Gonads located near middle of body, testis ovate; vas deferens passes forward near the median line of the body as a slightly undulant tube. Copulatory complex well developed and situated in a relatively large vestibule. Cirrus an elongate hollow chitinous tube tapered distally. Average length of cirrus 0.037 mm. (0.025-0.042 mm.). Accessory piece a solid chitinous blade-like structure with an enlarge- ment near the midlength. Proximal portion of accessory piece articulated with base of cirrus.
Egg pore located on ventral surface in the region of the copulatory complex. Vagina not clearly distinguishable. Vitellaria and vitelline ducts as given in the general morphology of the North American fresh-water Tetraonchinae.
Digestive and excretory systems.—Digestive and excretory systems as given in the general morphology of the North American fresh-water
Tetraonchinae. Average diameter of pharynx 0.031 mm. (0.029- 0.038 mm.).
Systematic position.—This species differs from other described species of Dactylogyrus by the nature of the copulatory complex. The anchors are similar to those of Dactylogyrus simplex Mizelle, 1937. A vestigial bar is lacking in Dactylogyrus atromaculatus n. sp., whereas one is present in D. simplex. D. atromaculatus has been collected only from the gills of the creek chub. It occurs in mixed infestations with an unde- scribed species of Dactylogyrus.
ECONOMIC IMPORTANCE
Trematodes are found abundantly in and on both marine and fresh- water fishes. That they cause serious damage to the host is demon- strated by the work of several authors. The results of Cross (1935) on four-year-old yellow perch (Perca flavescens) show that fish with light infestations averaged eighteen per cent longer and one hundred twenty per cent heavier than fish with heavy infestations. This work included observations on myxosporidian, cestode, nematode, and copepod parasites,
56 ILLINOIS BIOLOGICAL MONOGRAPHS
in addition to the ectoparasitic and endoparasitic trematodes.1 Bangham (1927) found that larval cestodes (Proteocephalus ambloplites) sterilized one hundred fifty small-mouth bass breeders in an Ohio hatchery. Out of three hundred ninety-one fish (Platygobio gracilis) Hubbs (1927) found sixty-eight individuals with abnormalities which he attributed to infestation with parasites, chiefly Proteocephalus and several species of trematode metacercariae.*?, The abnormal fish showed an increase in the number of scales, a retention of larval characters, and an average growth retardation of 4.5 mm. in length. In the production of abnormalities, Hubbs considered Proteocephalus more important than trematodes, but in a few cases he attributed relative damage to the latter since some abnormally developed individuals harbored heavy infestations of trema- todes and only a few specimens of Proteocephalus. Van Haitsma (1931) noted death of four out of a lot of nine ducks, which he was inclined to attribute to infestation with Cotylurus flabelliformis (Faust). The same author (193la) observed two experimentally infested suckers whose death he was sure was due to penetration with cercariae of Diplostomulum flexicaudum (Cort and Brooks). Van Haitsma (193la) quoted Bloch- man as having had the same experience with several fish placed in a tank with eight specimens of Lymnaea stagnalis shedding furcocercous cer- cariae (Cercaria fissicauda). Szidat (1927) cited Diplostomum spatha- ceum (Rud.) as being responsible for the death of thousands of Acerina cernua and Leuciscus rutilis. McCoy (1928) reported death of seven sunfish (Eupomotis gibbosus) by penetration of large numbers of Cercaria hamata Miller. Ferguson (unpublished data) in 1936 noted the death of several blunt-nosed minnows (Hyborhynchus notatus) experimentally infested with variable numbers of an unidentified furcocercous cercaria from Physa integra.
Bangham (1928) is of the opinion that “The internal flukes are probably the least harmful of the bass parasites, but those which are external often do considerable damage to the gills, skin, and fins of the host—especially where they are found in ponds where many bass are confined.” Hofer (1904) and Plehn (1924) considered Gyrodactylus as destructive to the skin and gills of various species of European fishes. Roth (1922) mentioned this organism as the etiological agent of a con- tagious disorder of carp, goldfishes, and other fish in aquaria and natural waters. Atkins (1901) recorded Gyrodactylus elegans von Nordmann in hatchery ponds and also in the wild waters of Maine. Cooper in 1915 re- ported Gyrodactylus medius Kathariner, on the small-mouth black bass of Canada. Van Cleave (1921) doubted the identity of Cooper’s species and
1Only one specific parasite was mentioned, namely Triaenophorus nodulosus (cysts).
*The genus Proteocephalus was the only identification made. Hubbs dealt only with endoparasites.
STUDIES ON TREMATODES—MIZELLE 57
believed it different from any described form. In the same publi- cation Van Cleave described Gyrodactylus fairporti in an epidemic from the common bullhead (Ameiurus melas) and the European carp (Cyprinus carpio) at Fairport, Iowa. Pratt (1929) recorded ectoparasitic helminth infestations on the gills of rainbow trout in the New York Hatchery at Cold Spring Harbor, and mentioned that the parasites were numerous enough in many cases to cause marked damage to the affected hosts. He did not determine the species, but his figure indicated it to be a species of Gyrodactylus. Ward (1918) noted the occurrence of Gyrodactylus in several localities attacking lake trout and small-mouth bass in the Eastern United States and Canada. Moore (1922) reported it as the causative agent of disease in fish hatcheries in New York, affecting trout primarily, and stated that its range was probably widespread. In 1924 Embody reported Gyrodactylus as responsible for considerable loss of trout in New Jersey where measures were undertaken to control its ravages. Hess (1928) noted serious losses in hatcheries among “fry” three to six weeks old by an unidentified species of Dactylogyrus. MacCallum (1915) found that members of the family Microcotylidae caused the death of ninety per cent of the angel and butterfly fishes in the tanks of the New York Aquarium. Guberlet, Hansen, and Kavanagh (1927) reported a daily mortality of one to two per cent for rainbow trout fingerlings (Salmo wideus shasta) infested with Gyrodactylus elegans, in a hatchery near Seattle, Washington, from November 15 to December 20, 1925. Two individuals (observed by the present author) out of a lot of sixteen black crappies (Pomoxis sparoides) transported by automobile from Lake Senachwine near Henry, Illinois, showed signs of suffocation and loss of balance on arrival at the laboratory at Urbana, Illinois. These two fish died approximately six hours later in one of the Illinois State Natural History Survey aquaria. On examination they were found heavily in- fested with Cleidodiscus capax Mizelle. The rest of the fish presented no particular symptoms of disease, and when examined at a later date were found to harbor only light infestations of the same species of parasite. It has been observed that yellow bass (Morone interrupta), which often harbor several hundreds of Onchocleidus interruptus Mizelle, on their gills, die soon after removal from the net when placed in containers filled with aerated water of the same temperature as that from which they were taken. Death of these hosts was prevented by cooling the water in con- tainers before placing the fish therein. During the spring of 1937 an epidemic among blunt-nosed minnows (Hyborhynchus notatus) by Dacty- logyrus bychowskyi Mizelle, was observed. Over three hundred hosts in an aquarium at the University of Illinois died during the epidemic. Steel colored minnows (Notropis whipplii) in the same tank were not affected.
58 ILLINOIS BIOLOGICAL MONOGRAPHS
The flukes were found to infest the gills of the hosts exclusively. As many as two hundred parasites were recovered from one fish in this epidemic, whereas twenty-five fish examined a few hours after removal from neighboring streams, namely the Drainage Ditch and Embarrass River, harbored an average of five parasites each. It has not as yet been determined whether these phenomena are due wholly to infestation with the specific gill trematodes mentioned. Van Cleave (1921) and Mueller and Van Cleave (1932) are in accord with Bangham (1928) in stating that infestations with ectoparasites are more apt to become serious in aquaria and artificial enclosures rather than in natural waters. The same idea was expressed by MacCallum (1915), but after his publication had gone to press he had occasion to examine several fish from the open sea, two of which were snappers (Priacanthus crwentatus), whose death he was certain was due to infestation with Diplectana. The present writer has not recorded a single epidemic of tetraonchid ectoparasites among infested sunfishes kept in aquaria for maximum intervals of four weeks. Records of epidemics or serious outbreaks of oviparous Gyrodactyloidea are not as numerous as for viviparous forms. Members of the genus Gyrodactylus, have been observed to harbor as many as two generations within a single parent.
The nature of damage by ectoparasitic trematodes to fish hosts is varied. MacCallum (1915) attributed the damage of Microcotyle to be of a double nature, namely the production of an anemia and suffocation. This author says that species of this genus (Microcotyle) fasten them- selves to the gills of fishes and that such attachment causes irritation which induces an outflow of mucus covering the gills, thus preventing access of water to the respiratory surfaces. Due to the feeding habits of these parasites, a depletion of the host’s blood supply occurs which renders it exsanguine, producing death. MacCallum (1927) recorded that in 1926 Miss Ida Mellen noted the destruction of the cornea of the Pacific puffer (Spheroides annulatus), the spade fish (Chaetodipterus faber), and several species of angel fishes of the genera Angelichthys and Pomacanthus by Epibdella melleni MacCallum. Tubangui (1931), in regard to Ancyrocephalus manilensis Tubangui, stated that the infested organs were much congested and showed numerous punctiform hemor- rhages, produced no doubt by the hooks of the parasite. Pratt (1929) mentioned a shriveling of the gills which rendered them functionless in heavy infestations of Gyrodactylus on rainbow trout. Van Cleave (1921) considered direct damage to the general body surfaces of fishes by Gyrodactylus fairporti Van Cleave, only one mode of parasitic attack and that additional damage was possibly done by bacteria, protozoa, and fungi, whose invasion of the host was made possible by removal of skin and scales by the armature of ectoparasitic helminths.
STUDIES ON TREMATODES—MIZELLE 59
The present author in examining over one thousand individuals be- longing to species of Tetraonchinae and Dactylogyrinae described herein, found infestations restricted to branchial tissues. This site of parasitic attack is in accord with the findings of MacCallum (1915) for the Octocotylidae, Microcotylidae, and Diplectana. The principal damage to fish hosts by the observed members of Tetraonchinae is accomplished presumably by an irritative or toxic action resulting from the insertion of the haptor. Each point of haptoral attachment on the branchial fila- ments of the black and white crappies (P. sparoides and P. annularis) by Cleidodiscus capax Mizelle, and of the bluegill sunfish (Helioperca macrochira) by Cleidodiscus robustus Mueller, generally present an en- larged circumscribed area denoting an apparent condition of hypertrophy or hyperplasia. These areas become thickly covered with mucus which prevents contact of the branchial surface with the water, recalling the condition of suffocation mentioned by MacCallum (1915) for members of the genus Microcotyle.
A knowledge of the specific etiological agent together with its com- plete life history is indispensable to the successful control of a disease. Until recently the incompleteness of such information concerning the North American Gyrodactyloidea Johnston and Tiegs, has been astonishing. MacCallum (1915 and 1927) described a number of species from marine fishes. Van Cleave (1921) described Gyrodactylus fair porti from Fairport, Iowa. Hess (1928 and 1930) recorded the presence of undetermined species of Dactylogyrus and Gyrodactylus on goldfishes and an undetermined species of Ancyrocephalus from several species of native fishes in Indiana and central New York. Stafford (1905), Cooper (1915), Ward (1918), Bangham (1926), and Guberlet, Hansen, and Kavanagh (1927) have given records of one or more instances of the occurrence of Gyrodactyloidea on fresh-water fishes, but have left doubts as to the identity of the forms with which they dealt, and in several instances made identification only to genus. In 1928 Bangham made no attempt to identify species of gill parasites of the large-mouth black bass (A plites salmoides). In 1933 the same author in his publication on the parasites of the spotted bass (Micropterus pseudaplites), which also included a summary of parasites of the small and large-mouth basses from Ohio streams, did not record a single ectoparasitic trematode for the spotted or Kentucky bass, and only one unidentified species of Ancyrocephalus for the other hosts. Since 1931 taxonomic work on this group has been relatively prolific (see page 13).
In regard to life histories of the Monogenea, only three are completely known. Of the Gyrodactyloidea, the life history of Gyrodactylus elegans von Nordmann was studied by Kathariner in 1904. The life history of Epibdella mellenit MacCallum, belonging to the Capsaloidea, was pub-
60 ILLINOIS BIOLOGICAL MONOGRAPHS
lished by Jahn and Kuhn in 1932. Zeller (1872a) published the life history of Diplozoon paradoxum, a member of Polyopisthocotylea. Zeller also published (1872) a description of the life history of Polystomum integerrimum, but this work has been doubted by many authors including Stunkard (1917). Hess (1928) gave a very superficial account of the life history of an unidentified species of Dactylogyrus which he found infesting the gills of the small and large-mouth black basses, common sunfish, goldfish, carp, and “other fishes.’’
In discussing possibilities of controlling endoparasites, different authors have suggested destruction of a unit in the chain of hosts utilized by a particular species, as a means of extermination of the etiological agent. Chandler (1920) suggested the killing of the snail host (which harbors intermediate stages of trematode parasites) in order to stamp out certain trematode diseases. Linton (1911) advocated the shooting of water birds as a measure for ridding fish of yellow grub or metacercariae of Clinostomum. Baker (1922) pointed out the danger of such practices by showing the relationships of Mollusca in food chains of aquatic organisms. In addition Baker called attention to the fact that agents such as copper sulphate used to kill snails were highly toxic to algae and other microscopic life on which higher animals depend for food.
Methods for extermination of monogenetic trematodes must of neces- sity differ radically from those used for digenetic forms because of a difference in life histories. In the light of our present knowledge, an intermediate host is not utilized by monogenetic flukes. Infection is ac- complished by contact (MacCallum, 1927), (Guberlet, Hansen, and Kavanagh, 1927) and when fish are subjected to crowded conditions, ectoparasitic trematodes often increase in numbers that effect a high mortality of the hosts as pointed out by MacCallum (1915), Van Cleave (1921), Guberlet, Hansen, and Kavanagh (1927), and others.
Various methods have been proposed for destruction of these trema- todes. Hubner (1895) recommended an exposure of infested fish to a one-fourth of one per cent solution of salicylic acid for thirty minutes. Hofer (1904) also recommended the treatment of Hubner and in addi- tion advocated a bath of one part of potassium permanganate to one hundred thousand parts of water. Plehn (1924) proposed an exposure of diseased fish for ten minutes to a two per cent solution of hydrogen peroxide and subjection to a one to eight thousand acetic acid bath from one to one and one-half hours as being specific for ectoparasites closely related to Discocotyle salmonis Schaffer. Davis (1929) found the acetic acid treatment ineffective. Laird and Embody (1931) also found the acetic acid bath of no benefit and determined treatment with a bath of copper sulphate and of saturated sodium chloride solution, as used by European fish culturists for one to one and one-half minutes (Davis
STUDIES ON TREMATODES—MIZELLE 61
1929), to be worthless. Through an indirect communication, the present author learned that Jahn successfully treated fish for Epibdella melleni by doubling the concentration of salt in sea water. Laird (1927) reported successful destruction of gill parasites by spraying the branchial tissue with a twenty per cent solution of Zonite. Laird and Embody (1931) recommended a two minute immersion of fish in a solution of Zonite made of one ounce of the chemical to ten to twelve quarts of water. Guberlet, Hansen, and Kavanagh (1927) found gyrodactyliasis, or fin disease of fish, very difficult to control. After a number of experiments with various chemicals they concluded that exposure to a four and one-half to five per cent solution of common salt for one and one-half to two and one-half minutes to be the safest and most effective treatment for the disease. Hess (1930) found that immersion of the host for two hours in a solu- tion of potassium permanganate (one pound to thirty-two thousand gallons of water) was absolutely specific for undetermined species of Gyrodactylus and Dactylogyrus on goldfishes. He also recommended spraying the surface of ponds with one pound of the dissolved chemical to twenty-five thousand to forty thousand gallons of water, depending on the amount of organic matter present, capable of reducing potassium permanganate. Hess observed that old fish withstood stronger solutions of this chemical better than did the younger individuals. Because of reduction of potassium permanganate by organic matter in hatchery ponds, this method becomes impractical due to the inability to correctly estimate the amount of organic material in the water. Water capacity of hatchery ponds must also be known for intelligent use of the anthelmintic.
Fish culturists and conservation agencies responsible for rearing and distributing fishes have given practically no attention to the dangers of transporting gill parasites into new regions. Except for a few of the large species, the gyrodactylids are so small as to escape field inspections. Furthermore, detailed information as to the species involved and the specific action of each on the host has been generally lacking. Doubtless the inconsistencies encountered by several authors, with various anthel- mintics recommended by other workers, were in part due to the fact that they dealt with ectoparasites other than those for which particular chemicals were found specific. Control measures aimed at a generalized treatment for ectoparasitic trematodes would probably be as meaningless as a generalized therapy for the multitude of human diseases. It is recom- mended that fishes infested with monogenetic trematodes be subjected to therapy one hundred per cent effective for removal of such parasites, before placing them in new environments as aquaria, fish hatcheries, or natural waters. New hosts for etiological agents of disease generally suffer high mortality until a physiological balance with the organism is established.
62 ILLINOIS BIOLOGICAL MONOGRAPHS
DISCUSSION
In a recent publication Mueller (1937) mentioned two systems of numbering the hooks on haptors of fresh-water species of North American Tetraonchinae. Contentions regarding the order of these structures are not of a serious nature, and only for the sake of future workers in this field are the following comparisons and deductions set forth. It must be remembered that any arbitrary system of numbering that deals with haptoral hooks in this group of parasites cannot be regarded as having unquestionable value. A natural system of numbering these hooks must be attained through embryological studies. In the absence of such studies, all systems of numbering must be regarded as highly artificial, derived solely as a matter of convenience, and discarded when basic information is produced. Information concerning the embryology of North American Tetraonchinae is as yet wanting.
Haptoral hooks, in North American fresh-water species of Tetra- onchinae (Tetraonchus and Murraytrema not studied) and Dactylogyri- nae, are distributed on both dorsal and ventral sides of the haptor, five pairs being on the ventral and two pairs on the dorsal side. In 1936 Mueller numbered the hooks consecutively around the margin of the haptor, beginning with the anterior central (ventral) pair of hooks as number one. Since the two dorsal pairs of hooks are variable in their positional relationships (in different species) with the five pairs of ventral hooks, the earlier proposed system of numbering (Mueller 1936) becomes very confusing. Discrepancies naturally occur in the older system of number- ing because of this fluctuation in the linear positions of the two pairs of hooks mentioned. For instance, the most anterior dorsal hook is labelled number six by Mueller for Onchocleidus mimus (1936, p. 59, pl. 13, fig. 13), two for O. similis (ibid., fig. 10), four for O. ferox (ibid., fig. 12) and number five for P. acer and H. dispar (ibid., figs. 9 and 11), whereas in the new system of numbering (Mizelle, 1936) each anterior dorsal hook consistently becomes number seven for each species. Since the hooks involved (all except number one) are generally identical in struc- ture in a given species, with varying size relationships in different species together with variable spatial relationships with each other, the stable character of ventral and dorsal distribution must be resorted to if any degree of regularity is to be attained. In the later proposed system of numbering (Mizelle, 1936) Mueller’s starting point is utilized for hooks of the first pair, but instead of zigzagging in some cases from one surface of the haptor to the other and in other cases going consecutively from
1In 1936 the present author described a variation of this arrangement for one species, viz., Actinocleidus articularis (Mizelle, 1936). All fourteen hooks were thought to occur on the same side of the haptor. In subsequent work, the hook arrangement of all species in this genus has
been found to agree with that existing in the other North American Tetraonchinae (fresh-water) genera possessing fourten haptoral hooks.
STUDIES ON TREMATODES—MIZELLE 63
ventral to dorsal side with the exclusion of the hook pair in the region of the ventral anchors, the sequence is posteriorly around the ventral side of the haptor and then dorsally in an anterior direction (figs. 173- 174). Hooks numbers six and seven always relate to those on the dorsal side of the haptor, number six being invariably the more posterior. The single pair of hooks whose position is in the region of the ventral anchors obviously becomes number five in the new system instead of seven in that of Mueller’s.
Mueller (1937) cited O. mimus and Cleidodiscus robustus as possess- ing the primitive hook arrangement, whereas in 1936 he referred to Actinocleidus oculatus as possessing it. The present writer has found the same basic hook arrangement present in all species examined. The species of Dactylogyrus described in this paper possess the same hook arrangement as the Tetraonchinae, and although the ventral pair of anchors has disappeared in this genus, a ventral chitinous structure is present in D. simplex, D. bifurcatus, and many other previously described species. This structure could very easily be interpreted to represent a remnant of the ventral bar that once connected the two members of the ventral pair of anchors. The genus Hapflocleidus Mueller, 1937, which is characterized by a marked difference in the size of the two pairs of anchors, strongly suggests an intermediate stage in the transition from a condition of four anchors to a condition of two anchors or one pair. The genus Gyrodactylus is assumed to be more specialized than either of the foregoing since only one pair of anchors is present without a vestige of the ventral bar; oviparity is replaced by viviparity; eye spots have disappeared in adults; and all the hooks (eight pairs) occur on the same side of the haptor.
The present writer is in general accord with Price (1937a) with reference to the possible invalidity of some of Mueller’s recently created genera, viz., Cleidodiscus, Urocleidus, Onchocleidus, Leptocleidus, Tetra- cleidus, Aristocleidus, Haplocleidus, Pterocleidus, and Actinocleidus. Species of Urocleidus are not unlike those of Onchocleidus except for the absence of a vagina, a condition which sporadically occurs in several genera of Tetraonchinae. Leptocleidus possesses characters common to the genus Cleidodiscus with which it is probably synonymous. Tetra- cleidus is distinguished from Onchocleidus (Mueller, 1936) by the pres- ence of an accessory piece in the copulatory complex. This structure has been described for practically all species of Onchocleidus. Aristocleidus is also like Onchocleidus except for a difference of size and shape rela- tionships of the dorsal and ventral anchors, a condition which occurs in other genera of this subfamily. Hapflocleidus was split off the genus Onchocleidus to include forms which possess dorsal anchors that are much larger than the ventral anchors. Recent research (Seamster, 1938)
64 ILLINOIS BIOLOGICAL MONOGRAPHS
has shown this condition to occur as a variation in Cleidodiscus pricei Mueller, 1936. Pterocleidus was also split off the genus Onchocleidus and made to include forms which possess a spur on each anchor shaft. This condition is thought to be of no more importance than occurrence of spines on the bars of Onchocleidus mucronatus Mizelle, O. cyanellus Mizelle, Cleidodiscus vancleavei Mizelle, and C. robustus Mueller. The genus Actinocleidus was taken from Cleidodiscus to embrace forms which have fused bars and both pairs of anchors on the same side of the haptor. This genus is held as valid. A revision of the North American fresh- water genera of Tetraonchinae is contemplated in the near future.
SUMMARY
A method has been perfected for removal of ninety-two per cent of the monogenetic flukes present on the gills of fresh-water fishes.
Successful attachment of small gyrodactyloid parasites to glass slides, to prevent loss of such material during technical processes requisite for production of permanent mounts, has been accomplished.
Twenty-one species of monogenetic trematodes of the subfamilies Tetraonchinae and Dactylogyrinae have been described from the gills of Illinois fishes. A few host records are reported from Oklahoma.
A review of the detrimental effects of monogenetic trematodes to fish hosts, together with a review of control methods for these parasites, is given.
A thorough subjection of fish hosts, infested with monogenetic trematodes, to procedures requisite for one hundred per cent removal of all stages of such parasites, is recommended before transplanting them in new environments, as aquaria, fish hatcheries, or natural waters.
Chitinous parts as anchors, bars, hooks, and copulatory structures are relatively constant and serve for definite identification of species of fresh- water Gyrodactyloidea especially when host-parasite relationships are known.
STUDIES ON TREMATODES—MIZELLE 65
BIBLIOGRAPHY Atkins, C. G. 1901. The study of fish diseases. Trans. Amer. Fish. Soc. 30:82-89. Baker, F. C. 1922. Fluke infections and the destruction of the intermediate host. Jour. Parasitol. 8(3) :145-147. BancuHam, R. V. 1926. Parasites other than cestodes in the black bass of Ohio. Ohio Jour. Sci. 26(3):117-127. 1927. Parasites as a limiting factor in Ohio fish hatcheries. Jour. Parasitol. 13(3) :214. 1928. Parasites of black bass. Scientific Monthly, Sept., 1928. 1933. Parasites of the spotted bass, Muicropterus pseudaplites Hubbs, and summary of parasites of smallmouth and largemouth black bass from Ohio streams. Trans. Amer. Fish. Soc. 63:220-227. Bycuowsky, B. 1929. Trematoden der Fische in der Umgebung der Stadt Kostroma. Travaux de la société des naturalistes de Leningrad 59(1) :3-27. 1931. Neue Dactylogyrus-Arten aus dem Aralsee. Zool. Anz. 95(9/10) :233-240. 1933. Beitrag zur Kenntnis neuer monogenetischen Fischtrematoden aus dem Kaspisee nebst einigen Bemerkungen uber die Systematik der Monopisthodiscinea Fuhrmann, 1928. J/bid. 105(1/2) :2-38. 1933a. Die Bedeutung der monogenetischen Trematoden fur die Erforschung der systematischen Beziehungen der Karpfenfische. [bid. 102(5/6): 243-251. 1933b. Eine neue Gyrodactylus-Art aus den Seen Kareliens. Berichte der Biolog. Boroden Sta. 6(2):51-55. 1934. Dactylogyrus cryptomeres n. sp. und einige Bemerkungen uber Mono- genea aus dem See Beloje. Zool. Jahrb. Abt. f. System, Okol. u. Geog. d. Tiere 65(2) :193-208. CHANDLER, A. C. 1920. Control of fluke diseases by destruction of the intermediate host. Jour. Agr. Res. 20(3) :193-207. Cooper, A. R. 1915. Trematodes from marine and fresh-water fishes, including one species of ectoparasitic turbellarian. Trans. Roy. Soc. Canada (3)9:181-205. Cross, S. X. 1935. The effect of parasitism on growth of perch in the trout lake region. Jour. Parasitol. 21(4) : 267-273. Davis, H. S. 1929. Care and diseases of trout. U. S. Bu. Fish. Doc. No. 1061. App. 4 Rept. of U. S. Commissioner of Fisheries 1929. Diesinc, Kk. M. 1858. Revision der Myzhelminthen. Sitsungsb. d. k. Akad. d. Wissensch., Wien, Math-naturw. cl. 32(23) :307-390. DocieEL, V., and BycHowsky, B. 1934. Die Fischparasiten des Aral-Sees. Magasin de Parasitol. de 1'Inst. Zool. de l'Acad. des Sci. de ’URSS 4:241-345. Empopy, G. C. 1924. Notes on the control of Gyrodactylis on trout. Trans. Amer. Fish. Soc. 54:48-53.
66 ILLINOIS BIOLOGICAL MONOGRAPHS
Forses, S. A., and RicHarpson, R. E. 1908. The fishes of Illinois. Natural History Survey of Illinois. Ichthyology. Foster, F. J. 1925. Notes on certain diseases of the rainbow trout. Trans. Amer. Fish. Soc. 55: 80-89. FUHRMANN, O. 1928. Zweite Klasse des Cladus Platyhelminthes: Trematoda. Handb. d. Zool. (Krumbach) 2:1-128. Goto, S. 1894. Studies of the ectoparasitic trematodes of Japan. Jour. College of Sci. Imperial Univ., Tokyo 8(1) :1-273. Goto, S., and Kixucut, H. 1917, Two new trematodes of the family Gyrodactylidae. Ibid. 39:1-22. GuperteT, J. E., Hansen, H. A., and Kavanaau, J. A. 1927. Studies on the control of Gyrodactylus. Pub. in Fisheries. Univ. Wash. College of Fisheries 2(2) :17-29. Hess, W. N. 1928. The life history and control of Dactylogyrus sp. Jour. Parasitol. 15(2) :138. 1930. Control of external fluke parasites on fish. [bid. 16(3):131-136. Horer, B. 1904. Handbuch der Fischkrankheiten. Stuttgart. Husss, C. L. 1927. The related effects of a parasite on a fish. Jour. Parasitol. 14(2) :75-84. Hupner, R. 1895. Die Verhandlungen des V. deutschen Fischereitages in Breslau, 28 und 29 Aug. 1894. Zeitschr. Fischerei 3:191. Hucues, W. K. 1929. Some trematode parasites on the gills of Victorian fishes. Proc. Roy. Soc. Victoria 41(1) :45-54. Jaun, T. L., and Kuwy, L. R. 1932. The life history of Epitbdella mellint MacCallum, 1927, a monogenetic trematode parasitic on marine fishes. Biol. Bull. 62(1):89-111. Jounston, T. H., and Tiecs, O. W. 1922. New gyrodactyloid trematodes from Australian fishes, together with a reclassification of the super-family Gyrodactyloidea. Proc. Linn. Soc. of New So. Wales 47(2) :83-131. KATHARINER, L. 1904. Ueber die Entwichlung von Gyrodactylus elegans v. Nordmann. Zool. Jahrb. Suppl. 7:519-548. Kutwiec, Z. 1927. Untersuchungen an Arten des Genus Dactylogyrus Diesing. Bull. intern. de l’acad. Polonaise Ser. B,113-144. Lairp, J. A. 1927. The use of Zonite in treating gillworms. Trans. Amer. Fish. Soc. 57:177-179. Larrp, J. A., and Emgopy, G. C. 1931. Controlling the trout gill worm (Discocotyle salmonis Schaffer). Trans. Amer. Fish. Soc. 61:189-191. Lesour, M. V. 1907. Fish trematodes of the Northumberland coast. Northumberland Sea Fisheries Report 1907:3-47.
STUDIES ON TREMATODES—MIZELLE 67
Linstow, O. von
1875. Beobachtungen an Neuen und bekannten Helminthen. Naturges. 41(1): 183-206.
1878. Neue Beobachtungen an Helminthen. /bid. 44(1) :218-244.
Linton, E.
1911. Trematode parasites in the skin and flesh of fish and the agency of
birds in their occurrence. Trans. Amer. Fish. Soc. 41:245-259. Luue, M.
1909. Parasitische Plattwurmer. 1. Trematodes. Susswasserfauna Deutsch-
lands 17. McCoy, O. R. 1928. Life history studies on trematodes from Missouri. Jour. Parasitol. 14(4) : 207-228. MacCatium, G. A. 1915. Some new species of ectoparasitic trematodes. Zoologica 1(20) :395-410. 1927. A new ectoparasitic trematode. Zoopathologica 1(8) :291-300. MELLEN, Iba. 1928. The treatment of fish diseases. Zoopathologica 2(1):1-31. Mizetre, Joun D.
1936. New species of trematodes from the gills of Illinois fishes. Amer. Midl. Nat. 17(5) :785-806.
1937. Ectoparasites of the blunt-nosed minnow (Hyborhynchus notatus). Ibid. 18(4) :612-621.
1938. New species of monogenetic flukes from Illinois fishes. /bid. 19(2): 465-470.
1938a. Notes on ectoparasitic trematodes of fishes. Trans. Ill. State Acad. Sci. 30(2) :311-312.
Moore, EMMELINE.
1922. Diseases of fish in state hatcheries. 12th Ann. Rept. State N. Y. Cons. Com., Bu. Prevention of Stream Pollution: 18-31.
1928. The treatment of fish diseases. Zoopathologica 2:1-31.
MUELLER, J. F.
1934. Parasites of Oneida Lake fishes, part 4, additional notes on parasites of Oneida Lake fishes, including descriptions of new species. Roosevelt Wild Life Annals 3(4) :335-373.
1936. Studies on North American Gyrodactyloidea. Trans. Amer. Micros. Soc. 55(1) :55-72.
1936a. New gyrodactyloid trematodes from North American fishes. bid. 55(4) :457-464.
1937. Further studies on North American Gyrodactyloidea. Amer. Midl. Nat. 18 (2) :207-219.
1937a. The Gyrodactylidae of North American fresh-water fishes. Fish Culture, January, 1937.
1938. Additional species of North American Gyrodactyloidea (Trematoda). Amer. Midl. Nat. 19(1) :220-235.
MuELter, J. F., and Van Creave, H. J.
1932. Parasites of Oneida Lake fishes, part 2, descriptions of new species and some general taxonomic considerations, especially concerning the trematode family Heterophyidae. Roosevelt Wild Life Annals 3(2) :77-137.
Murray, F. V. 1931. Gill trematodes from some Australian fishes. Parasitol. 23(4) :492-506
68 ILLINOIS BIOLOGICAL MONOGRAPHS
Nicoti, WM. 1924. A reference list of the trematode parasites of British fresh-water fishes. Parasitol. 16(2) :127-144. Nyse LIN, O. 1924. Dactylogyrus vastator n. sp. Arkiv fur Zoologie 16(28) :1-2. OpDHNER, T. 1912. Die Homologien der weiblichen Genitalwege bei den Trematoden und Cestoden. Zool. Anz. 39:327-351. O’DonneEL, D. J. 1935. Annotated list of the fishes of Illinois. Ill. State Nat. Hist. Sur. Bull. 20:472-500. PLenn, M. 1924. Praktikum der Fischkrankheiten. Stuttgart. Pratt, H. S. 1900. Synopsis of North American invertebrates. 12. The trematodes. Part 1. The Heterocotylea or monogenetic forms. Amer. Nat. 34(404): 645-661. 1929. Parasites of fresh-water fishes. Bu. Fish. Ec. Cir. 42, revised. 1935. Manual of the common invertebrate animals. Blakiston, Philadelphia. Price, E. W. 1934. New monogenetic trematodes from marine fishes. Smith. Misc. Coll. 91(18) :1-3. 1934a. A new term for the adhesive organs of trematodes. Proc. Helm. Soc. Wash. 1(2) :34. 1936. North American monogenetic trematodes. Geo. Wash. Univ. Bull. 1937a. North American monogenetic trematodes. 1. The superfamily Gyrodactyloidea. Jour. Wash. Acad. Sci. 27(3):114-130; and (4): 146-164. Rotu, W. 1922. Die Krankheiten der Aquarienfische und ihre Bekampfung. Stuttgart. SEAMSTER, A. 1938. Studies on gill trematodes from Oklahoma fishes. Amer. Midl. Nat. (in press). Stwak, J. 1931. Ancyrocephalus vistulensis n. sp. un nouveau trematode parasite, du silure (Siluris glanis L.). Bull. de l’Acad. Polonaise des Sci. et des Lettres, Serie B(11) :670-679. STaFForD, J. 1905. Trematodes from Canadian vertebrates. Zool. Anz. 28:681-694. StunKarp, H. W. 1917. Studies on North American Polystomidae, Aspidogastridae, and Paramphistomidae. Ill. Biol. Monographs 3:285. Summe_rs, W. A. 1937. A new species of Tetraonchinae from Lepomis symmetricus. Jour. Parasitol. 23 (4) :432-434. Szipat, L. 1927. Uber ein Fischsterben in Kurischen Haff und seine Ursachen. Zeit. f. Fisch. und deren Hilfswiss. 25:83-90. TuHompson, D. H., and Hunt, F. D. 1930. The fishes of Champaign County. Ill. State Nat. Hist. Sur. Bull. 19:5-101.
STUDIES ON TREMATODES—MIZELLE 69
Tusancul, M. A. 1931. Trematode parasites of Philippine vertebrates. 4. Ectoparasitic flukes from marine fishes. Philippine Jour. Sci. 45(1):109-117. Van CLEAVE, H. J. 1921. Notes on two genera of ectoparasitic trematodes from fresh-water fishes. Jour. Parasitol. 8(1) :33-39. Van Cieave, H. J., and Mue ter, J. F. 1932. Parasites of Oneida Lake fishes, part 1, descriptions of new genera and new species. Roosevelt Wild Life Annals 3(1) :5-71. 1934. Parasites of Oneida Lake fishes, part 3, a biological and ecological sur- vey of the worm parasites. /bid. 3(3) : 159-334. Van Haitsma, J. P. 1931. Studies on the trematode family Strigeidae (Holostomidae) No. 22. Cotylurus flabelliformis (Faust) and its life history. Papers Mich. Acad. Sci. Arts and Letters 13:447-482. 193la. Studies on the trematode family Strigeidae (Holostomidae) No. 23. Diplostomum flexicaudum and stages in its life history. Ibid. 13: 483-5106. WaceEner, G. R. 1857. Beitrage zur Entwichlungsgeschichte der Eingeweidewurmer. Naturk. Verhandel. Holl. Maatsch. Wetensch. Haarl. 1857a. Helminthologische Bemerkungen aus einem Sendschreiben an C. Th. v. Siebold. Zeitsch. f. Wissensch, Zool. Leipz. 9(1) :73-90. Warp, H. B. 1918. Parasitic flatworms. Ward and Whipple's Fresh-water biology 265-453. WEDL, C. 1858. Anatomische Beobachtungen tiber Trematoden. Sitzungsb. d. k. Akad. d. Wissensch. Wien, Math-naturw. cl. 26(1) :241-278. WEGENER, G. 1909. Ektoparasiten der Fische Ostpreussens. Schrift. d. Phys. Okon. Gesellsch. z. Konigsberg 50:218-247. Yamacutl, S. 1934. Studies on the helminth fauna of Japan, part 2. Trematodes of fishes 1. Jap. Jour. Zool. 5(3) :249-540.
ZANDT, F. 1924. Fischparasiten des Bodensees. Ztrbl. Bakt. u. Parasitenk. 92(3/4): 225-271. ZELLER, E.
1872. Untersuchungen iiber die Entwicklung und den Bau des Polystomum integerrimum Rud. Zeitschr. f. wiss. Zool. 22(1) :1-24.
1872a. Untersuchungen iiber die Entwichlung des Diplozoén paradoxum. Ibid. 22(2) :168-180.
STUDIES ON TREMATODES—MIZELLE . 71
PLATES
All figures were drawn with the aid of a camera lucida (except 173 and 174 which are diagrammatic). The scale used is indicated on each plate.
72
ILLINOIS BIOLOGICAL MONOGRAPHS
PLATE I
Fic. 1—Cleidodiscus robustus Mueller, 1934. Fic. 2—Onchocleidus interruptus Mizelle, 1936. Fic. 3.—Onchocleidus principalis Mizelle, 19306. Fic. 4—Cleidodiscus longus Mizelle, 1930.
Fic. 5.—Cleidodiscus vancleavet Mizelle, 1936. Fic. 6—Cletdodiscus bedardi Mizelle, 1936.
Abbreviations
CC. Copulatory complex PH Pharynx CL Cephalic lobe SG Shell gland ES Eye spots SR Seminal receptacle GC Cephalic glands SV Seminal vesicle H Haptor T Testis HO Head organs UP Egg or uterine pore IC Intestinal crura UT Oviduct or uterus M Mouth V Vagina OV Ovary VD Vas deferens P, Prostate containing finely VDT Vitelline duct granular hyaline fluid VIT Vitellaria
P, Prostate containing coarsel y granular yellowish fluid
73
STUDIES ON TREMATODES—MIZELLE
I
ALW Id
74
Fic. Fic. Fic. Fic. Fic. Fic.
ILLINOIS BIOLOGICAL MONOGRAPHS
PLATE II Abbreviations same as for Plate I
7—Cleidodiscus capax Mizelle, 1936. 8—Onchocleidus distinctus Mizelle, 1936. 9—Onchocleidus mucronatus Mizelle, 1936. 10.—Actinocleidus articularis (Mizelle, 1936). 11—Pterocleidus acuminatus (Mizelle, 1936). 12.—Cleidodiscus uniformis Mizelle, 1936.
75
STUDIES ON TREMATODES—MIZELLE
Il HLV
Id
76
PLATE III Cleidodiscus robustus Mueller, 1934 Fic. 13. Accessory piece. Fic. 18.—Dorsal anchor. Fic. 14.—Cirrus. Fic. 19.—Ventral anchor. Fic. 15.—Vagina. Fic. 20.—Dorsal bar. Fic. 16.—Vaginal tube or canal. Fic. 21.—Ventral bar. Fic. 17.—Seminal receptacle. Onchocleidus mucronatus Mizelle, 1936 Fic. 22.—Cirrus. Fic. 27.—Ventral bar. Fic. 23.—Accessory piece. Fic. 28.—Vagina. Fic. 24.—Dorsal anchor. Fic. 29.—Vaginal tube or canal. Fic. 25.—Ventral anchor. Fic. 30.—Seminal receptacle. Fic. 26.—Dorsal bar. Cleidodiscus vancleavei Mizelle, 1936 Fic. 31.—Accessory piece. Fic. 36.—Vaginal tube or canal. Fic. 32.—Cirrus. Frc. 37—Seminal receptacle. Fic. 33.—Dorsal anchor. Fic. 38.—Dorsal bar. Fic. 34.—Ventral anchor. Fic. 39.—Ventral bar. Fic. 35.—Vagina. Actinocleidus articularis (Mizelle, 1936) Fic. 40.—Anterior anchor. Fic. 45.—Vaginal tube or canal. Fic. 41.—Anterior bar. Fic. 46.—Seminal receptacle. Fie. 42.—Posterior anchor. Fic. 47.—Accessory piece. Fic. 43.—Posterior bar. Fic. 48.—Cirrus. Fic. 44—Vagina. Cleidodiscus longus Mizelle, 1936 Fic. 49.—Dorsal_ bar. Fic. 53—Vaginal tube or canal. Fic. 50.—Ventral bar. Fic. 54.—Seminal receptacle. Fic. 51—Cirrus and accessory Fic. 55.—Dorsal anchor. piece. Fic. 56.—Ventral anchor. Fic. 52.—Vagina. Cleidodiscus bedardi Mizelle, 1936 Fic. 57.—Dorsal bar. Fic. 62—Ventral anchor. Fic. 58.—Ventral bar. Fic. 63.—Vagina. Fre. 59.—Cirrus. Fic. 64.—Pseudovagina. Frc. 60.—Accessory piece. Fic. 65.—Vaginal tube or canal. Fic. 61—Dorsal anchor. Fic. 66.—Seminal receptacle.
ILLINOIS BIOLOGICAL MONOGRAPHS
STUDIES ON TREMATODES—MIZELLE
PLATE III
77
78
Fic. Fic. Fic. Fic. Fic.
Fic. Fic. Fic. Fic. Fic.
Fic. Fic. Fic. Fic. Fic.
Fic. Fic. Fic. Fic. Pic.
Fic. Fic. Fic.
Fic. Fic. Fic. Fic. Fic.
ILLINOIS BIOLOGICAL MONOGRAPHS
PLATE IV Cleidodiscus capax Mizelle, 1936 67.—Accessory piece. Fic. 72.—Vaginal tube or canal. 68.—Cirrus. Fic. 73.—Seminal receptacle. 69.—Dorsal anchor. Fic. 74.—Dorsal bar. 70.—Ventral anchor. Fic. 75.—Ventral bar. 71.—Vagina. Onchocleidus principalis Mizelle, 1936 76.—Dorsal anchor. Fic. 81.—Accessory piece. 77.—Ventral anchor. Fic. 82.—Cirrus. 78.— Vagina. Fic. 83.—Dorsal bar. 79.—Vaginal tube or canal. Fic. 84.—Ventral bar. 80.—Seminal receptacle.
Cleidodiscus untfornrs Mizelle, 1936
85.—Dorsal bar. Fic. 90.—Cirrus.
86.— Ventral bar. Fic. 91.—Vagina.
87.—Dorsal anchor. Fic. 92—Vaginal tube or canal. 88.—Ventral anchor. Fic. 93.—Seminal receptacle. 89.— Accessory piece.
Pterocleidus acuminatus (Mizelle, 1936)
94.—Dorsal bar. Fic. 99.—Accessory piece. 95.—Ventral bar. Fic. 100.—Cirrus.
96.— Vagina. Fic. 101—Dorsal anchor. 97.— Vaginal tube or canal. Fic. 102—Ventral anchor.
98.—Seminal receptacle.
Onchocleidus interruptus Mizelle, 1936
103.—Dorsal anchor. Fic. 106.—Ventral anchor.
104.—Cirrus. Frc. 107.—Dorsal bar.
105.—Accessory piece. Fic. 108—Ventral bar. Onchocleidus distinctus Mizelle, 1936
109.—Dorsal bar. Fic. 114.—Vagina.
110.—Ventral bar. Fic. 115.—Vaginal tube or canal.
111.—Dorsal anchor. Fic. 116.—Seminal receptacle.
112.—Accessory piece. Fic. 117.—Ventral anchor.
113.—Cirrus.
STUDIES ON TREMATODES—MIZELLE 79
106
N7
PLATE IV
80
Fic. Fic. F xc:
Fic. Fic. Fic.
Fic. Fic. Fic.
Fic. Fic. Fic.
Fic. Fic. Fic. Fic.
Fic. Fic. Fic.
Fic. Fic. Fic.
Fic. Fic. Fic. Fic.
Fic. Fic. Fic. Fic.
Fics. 173-174.—Side and ventral views of haptors to show arrangement of hooks.
ILLINOIS BIOLOGICAL MONOGRAPHS
PLATE V
Dactylogyrus bychowskyi Mizelle, 1937 118.—Anchor. Fic. 121.—Accessory piece. 119.—Bar. Fic. 122.—Hooks. 120.—Cirrus.
Dactylogyrus bifurcatus Mizelle, 1937 123.—Dorsal bar. Fic. 126.—Cirrus. 124—Accessory piece. Fic. 127.—Anchor. 125.—“Ventral bar.” Fic. 128.—Hooks.
Dactylogyrus simplex Mizelle, 1937 129.—Anchor. Fic. 132.—“Ventral bar.” 130.—Hooks. Fic. 133.—Accessory piece. 131.—Dorsal_ bar. Fic. 134.—Cirrus.
Onchocleidus cyanellus n. sp. 135—Ventral anchor. Fic. 138.—Hook. 136.—Copulatory complex. Fic. 139.—Ventral bar. 137.—Dorsal bar. Fic. 140.—Dorsal anchor. Cleidodiscus diversus n. sp. 141.—Dorsal anchor. Fic. 145.—Dorsal bar. 142.—Accessory piece. Fic. 146.—Ventral bar. 143.—Cirrus. Fic. 147.—Hook. 144.— Ventral anchor.
Actinocletdus fergusont n. sp.
148.—Anterior anchor. Fic. 151.—Posterior bar. 149,.—Anterior bar. Fre. 152—Accessory piece. 150.—Posterior anchor. Fie. 153.—Cirrus.
Dactylogyrus atromaculatus n. sp. 154.—Cirrus. Fic. 157.—Hook. 155.—Accessory piece. Fic. 158—Anchor. 156.—Bar.
Urocleidus umbraensis n. sp.
159.—Dorsal anchor. Fic. 163.—Dorsal bar. 160.—Ventral anchor. Fic. 164.—Ventral bar. 161.—Accessory piece. Fic. 165.—Hook. 162,.—Cirrus.
Actinocleidus longus n. sp.
166.—Anterior anchor. Fic. 170.—Hook. 167.—Anterior bar. Fic. 171.—Accessory piece. 168.—Posterior anchor. Fic. 172.—Cirrus. 169.—Posterior bar.
STUDIES ON TREMATODES—MIZELLE
170
PLATE V
UN nt ar ir
Sanehijinenen iPatilysnaalt HUMIC RG RA Bey NEN Eee aytyle Ee RABA DING Rliebedr rp ate: init * at f ee ah i HV PUR EARL DUB LEIA ti hile! ah marie inh beebey ravines Maeta ty ) J , aa Bowl inl bs if JUserairdeyeyen) i tH i belie pe ery) " H t ' FVORHONoRAR eGo ri ha, wbraaitnel thepey f ‘ ‘ vue ve paMe pratt iinoedeheds bebe ke aa aids Loatatha ede hrenpaeceanet ne Wires Hear | i gery ed ALE Ri EAA) ocd HORA eel NUAMMGU IEA SHU MNP ATID Weanite i i ' i i i) PPVAUDI RIL MECC ean i} Vn tad oh titan ; HARA itheunnsga i late a Arata eiieinraneds ales gedy essen i HSN AU Hy ; Pods albd hich bf bit IR OL ane ea Ray Furie MREHE MPG Hbehebece itieamiceyoe eto eet Risurtr aunts atau aan NOS ; Tose te tets THY Pin hrc deni ra eaHe Ute vane i EMH iIVeMeR ta i saenentas WrOrarhedadiegrd ATOM PALE baie lp Evr demas iPREURTE WER st ( OeUHith i naive eae , LA eb ea ie PP RUTH CCE DRO Ae HRSAHIPUEROAE DeMeatHE HEA Ue beRrhry Heute nant Hale iitonorgay hepa scaunieuntapeyeanicjeyneians rit ney Ht isiys ep t ri SUNBH aE Garde gE HEE HE MUENCHL TENE MEMEMEGEOEGIIEMEDRUDU FAL Ri arr ( bh Fy bp AHH VCHMNA HE MA UPGmiv ele Blnmla ine orh ii bile Huda un } ( vida A Oana vat bhgsaniretweiut dae |ty CHACAMAN Mr pena LwbakAcaopoat teat i EWE Mi: HoWeAlsaedieoetys yar HIHAT oA Piel PbeAMie abel risar jens ude High HR nein sieaiusvranthae POA MAIL MRM eM MT en a i rurierunisiein Unag cise Meivarcunouiicignacuiaguai Con genitoskinie acon sane tibia EN ta Hite Latisin th 1 egHlknk subi HOUHHOGUANGENRULABACGRANOLMFARUE RemURCReNtTEACHTTERU RNG Wh feitratostuvttitl net Ht easobusuniritisbetioyriaanhoneae guy syn WVU PUM EUPMea bem baweruaed ens heied ep PUsAeUS OYE Pena Aeda at an ; seit : reiehsinavortwoenuaningtpaatitr tates tM mde dounat ausaturadgnyisnecapevtne a nunieden tutor Gund HAM oA t | Tarelynitesitupulerinee lit als UHaTUPanee as ceutaca Ou AeehLaEpUaneMuUtnUnN Vor cama ata ! nee Feanataniiie heeds ae salam ntatn Can Puna ve inet alta ' aA Rat ih ravAnngagipeanse rare yarpegel DSHS MH AC ! i lean UPdueutaritisdeRcreop cyt rvancenepeantatnee esa cate aM Honrbaeys any canong ti ni 4} tka hth A UMIALHOIHULUDURKUAMeRnedehr He dedtURurdeiedireedelemenriehier deur meucorusiedeieh N HH Hine ve KN f dire nena reads tegedsqtoon tease luun adetan taua(t ati nitesunutvtyattysaul i noptaauncatacgeant pat ' Ha 4 icaesroseaconiequtiturseaecyuatatacant gtatst) CHC NC A iy brrrwtocutans bor itera turnin pac ier natty Aonutuogr beatinctUe nu taMeM Qe wht a AM ANNE ; PUM oMm ett nc HARKrRE Re HEMtebe TUR Edinensheur asd (epee leAilrued: HeurRIAGHiRIVEY VHS Herm EaRMKREUD rnc A ASEA MoH HAN he EWE ODI EOF hes: it LUA ordiba PERNA MLGte PUT ok td baste MA PRL GALA ba ACTA GA od cae Ee at eK Re aa Pa brat RH Dl Pi iS} f ieeaenc giant: Ceo Mame UCapam Mult ehenbae eh icn Uengh ait behest (nd UMnF Ate De GRhbUCHPRUTUTBUAsHWIMt [suc gt r th ci } ritiepeatnatal ANGMAR CHASM MURAL LAE ede Gene neliepe (emma Medel Need OM oe GU Mehr HM MKCL Lb (ie Ge DNL i mo nhl tiseeaeicin ini choausnsatiniruabncnutanicanunce(eiuas ieyity lot ose teanicdceebercaeaeatner esprit acccivoceett i ne Ppl ether lal HENNE RAO He HEL Mrmr eM RMeHeme(anednbelibdabitiriie dere aatene le brirkolldeliaheseGenli«Weashenrhelols ie "