Morphology, microhabitats and geographical variation of Kuhnia spp. (Monogenea: Polyopisthocotylea)

InlernotionalJournalforParasilologV Printed in Great Britain.

Vol. 15, No. 5,pp.

569-586,

1985. 0

1985 Ausfrolion

co2&7519/85 s3.fM+o.oo Pergamon Press Lld. Sociefy for Porosiro/ogy

MORPHOLOGY, MICROHABITATS AND GEOGRAPHICAL VARIATION OF KUHNIA SPP. (MONOGENEA : POLYOPISTHOCOTYLEA) K. ROHDE and N. WATSON Department of Zoology, University of New England, Armidale, N.S.W., 2351, Australia (Received 2 January 1985) Abstract-RoHnE K. and WATSONN. 1985. Morphology, microhabitats and geographical variation of Kuhnia spp. (Monogenea: Polyopisthocotylea). International Journal for Parasitology 15:569-586. Kuhnia scombri and K. sprostonae are the only species of the genus recognized as valid. Hosts are scombrid fishes and possibly the genus Scomber only. Examination of many populations from localities in the Atlantic and Pacific showed much geographical variation. Variation is greatest in K. sprostonae, with a distinctly different population on S. scombrus in the North Atlantic. There are intermediate stages in all characters between different populations of both species (except possibly K. sprostonae in the North Atlantic). Some populations within each species have different microhabitats on the gills and pseudobranchs. Differences between parasite populations correspond to some degree to those of host populations, but at least some of the differences are non-adaptive. INDEX KEY WORDS: Kuhnia scombri; Kuhnia sprostonae; Monogenea; Polyopisthocotylea; zoogeography; speciation; coevolution; host specificity; microhabitats; site specificity; morphology.

INTRODUCTION STUDIESof many

groups have shown that species numbers within particular geographical areas are greater than expected, due to the existence of sibling species. The technique of isoenzyme focusing has proved particularly useful in detecting morphologically similar species. On the other hand, studies of species with a wide geographical distribution have sometimes led to a decrease in the number of recognized species, because many morphologically originally described as distinct populations, “species”, have been found to be geographical subspecies of one species, with intermediate forms occurring in areas of contact between subspecies (for examples see Mayr, Linsley & Usinger, 1953). Parasite taxonomy lags behind that of many groups of free-living animals, especially the vertebrates. For example, of the close to 1500 species of Monogenea (Yamaguti, 1963, and many later papers), many from different hosts and geographical areas differ only slightly in some organ measurements. It seems likely that many of them should be relegated to the status of subspecies or populations of a single species. This study set out to examine the possible geographical variation in the genus Kuhnia. animal

MATERIALS AND Numbers of Scomber spp. examined for gill monogeneans examined) are given below. Scomber austraiasicus, Jervis

METHODS from various localities (or number of worms. Bay, NSW (Fish caught

January 1984:-223 (of 64 only pseudobranchs examined): Sydney Market, NSW (January 1984)-60; Miuramisaki, Jaoan (May 1978. USNM 022503)-l: Tokyo Market. Japan (August-September 1966; USNM 228632, 228544) -4; Honolulu, Hawaii (USNM 062356)-l; Hawaii (USNM 052808)-l; Amoy, China (May 1977, USNM 221271)-l; Alumahan Bato, Philippines (September 1963, USNM 266801)-9; Negros Island, Philippines (June 1976, USNM 219798)-l. Golden Bay, New Zealand (September 1982)-3 Kuhnia scombri. Scomber scombrus. Helgoland, North Sea (August 1978, August-September 1982)-> 500; Yugoslavia (September 1968, USNM 227414, 267769)-6; Tunisia (March 1968, USNM 267770, May 1972, USNM 267768)-4; Mediterranean Morocco (July 1969, USNM 267767)-3; Bay of Naples (October 1923, USNM 086323)-Gulf of Maine, Georges Bank, USA (August 1949, USNM 163737, October 1954, USNM 163738/9)-6; Gloucester, Massachusetts, USA (October 1879, USNM 023370)-l; Bay of Biscay (Brit. Mus. Nat. Hist. 39/12)-3. Kuhnia scombri; Guernsey, British Channel (Brit. Mus. Nat. Hist; 1924. 3.15.6-lo)-3 Kuhnia scombri. Scomber japonicus. Slo Paulo State, Brazil (FebruaryMarch 1979)-98; Mar de1 Plata, Argentina (November 1970, December 1977, January 1980)-92; Capetown, South Africa (December 1980, USNM 226009)-6; Mediterranean Turkey (USNM 132303)-7; Haifa, Israel (May 1955, USNM 266920)-3; Atlantic Spain (June 1969, USNM 218960)-l; Hakodate, Japan 1889, USNM 048151, October 1896, USNM 049475, 1893, USNM 044911, July 1906, USNM 117913)-7; Tokyo Market, Japan (August 1966, USNM 228619)-4; Ecudador (May 1966, USNM 218976)-3; Santa Barbara, California (USNM 026276)-l. Of these fish, the following were infected with Kuhnia sprostonae: Scomber scombrus, Helgoland, North Sea; S. japonicus, Sno Paulo State, Brazil; Ecuador; S.

569

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K. ROHDEand N. WATSON

australasicus, New South Wales, Australia; Hawaii (USNM 062356). The following fish yielded Kuhnia scombri: Scomber scombrus, Helgoland, North Sea; Mediterranean (USNM 227414, 267768-70); Gulf of Maine, Georges Bank, North America (USNM 163737, 163738/9); S. japonicus. SBo Paulo State, Brazil; Mar de1 Plata, Argentina; Ecuador (USNM 218976), Hakodate, Japan (USNM 117913); Haifa, Mediterranean Israel (USNM 266920); Capetown, South Africa (USNM 226009); S. australasicus, Jervis Bay and Sydney Fish Market, New South Wales, Australia; Alumahan Bato, Philippines (USNM 266801). Three specimens of Kuhnia scombri collected from S. australasicus in Golden Bay, New Zealand, and three worms each of the same species collected from S. scombrus at Guernsey, English Channel and in the Bay of Biscay respectively, were also examined. Fish from the U.S. National Museum were preserved in 70% alcohol, fish bought on the Sydney Fish Market and their monogeneans were already dead, fish in Jervis Bay were caught by ring net and their monogeneans were still alive. Worms were collected under a dissecting microscope and, if still alive, fixed in hot 10% formalin. Dead unpreserved worms were fixed in cold 10% formalin. Whole specimens were mounted in Canada balsam either unstained or after staining with Grenacher’s carmine alum. Serial longitudinal sections were stained with haematoxylineosin. Clamps were examined after treatment as follows: specimens washed in water, partially digested in trypsin (62.5 mg ml-l in 0.05 M phosphate buffer at pH 8.0) for 3-5 h at 37°C with frequent shaking, washed several times to remove trypsin, stained overnight (12-24 h) in O&IO5%malachite green, washed in water, dehydrated in an alcohol series, cleared in xylene and mounted in Canada balsam. The following numbers of worms were examined by this method or by examination’of whole mounts for their clamp structure: Kuhnia scombri from Scomber scombrus, Mediterranean (22), North America (13), North Sea (50); from S. japonicus, Mediterranean (9), Argentina (l), Brazil (9), Japan (8) South Africa (5), Ecuador (13); from S. australasicus, New South Wales (23); K. sprostonae from S. scombrus, North Sea (12); S. japonicus, Ecuador (13), Brazil (24); S. australsicus, New South Wales (5), Hawaii (2). Details of hamuli and genital hooks were examined and measurements taken in squashes prepared as follows: whole worms or parts containing the hamuli or hooks left in 45% acetic acid for a few minutes, squashed between coverslip and slide to spread hamuli and hooks in one plane, dehydrated by repeatedly drawing absolute alcohol under coverslip and mounted in Euparal. Drawings were made with the aid of a camera lucida and measurements taken with calibrated eyepieces. Measurements of paired organs (buccal suckers, hamuli) are given as the means of both organs, if both could be measured. If not, the measure-

ments are given of only one of the pair. One large and one small’genital hook of each worm was measured, i.e. those which were spread best. The terminology for clamp sclerites is that used by Mamaev (1982). For the cluster analysis (Fig. 13), the TAXAN clustering program (Burr, 1968, 1970) was used, standardizing for variance and clustering by the weighted average strategy. Means for each locality were adjusted for (length + width)/2 where appropriate (i.e. buccal suckers, clamps, opisthaptor, pharynx) or length. Up to 10 quantitative (Tables 3.4) and two qualitative characters (shape of opisthaptor and hamuli) were used for each locality. Differences in clamp structure were not used.

I.J.P. VOL.15. 1985 RESULTS

(1967) and Collette & Nauen (1983) recognize three species of the genus Scomber, viz. S. scombrus in the eastern and western North Atlantic and adjacent seas, S. australasicus in the Pacific, and S. japonicus in the Atlantic and Pacific (Fig. 1). Each of these fish species harbours populations of two species of the polyopisthocotylean genus Kuhnia, family Mazocraeidae. For example, Scomber scombrus in the North Sea is infected with Kuhnia scombri and K. sprostonae illustrated in Fig. 2. Both have the following characters in common: Two septate buccal suckers, small pharynx and short oesophagus, two caeca with lateral and medial diverticula; opisthaptor with four pairs of clamps of the mazocraeid type consisting of five sclerites; terminal lappet carrying one pair of hamuli, one pair of marginals I and rarely one pair of marginals II; testes lateral and posterior to ovary, long sperm duct in midline; copulatory organ with one central pad carrying two rows of solid genital hooks often in anterior and posterior groups, and two lateral pads each with one solid large genital hook; ovary in middle of body, distal and proximal ends adjacent and directed anteriorly; genito-intestinal canal present; bifurcation of yolk duct slightly anterior to front of ovary; uterus opens through ventral common gonopore; no vaginae. Major differences between the two species on S. scombrus in the North Sea are the shape of the opisthaptor, the anterior end of which is clearly separated from the body proper in K. scombri but not in K. sprostonae, the larger size of the hamuli and their broader handle in the former species, the posteriorly joined caeca which extend almost to the end of body, and the larger clamps in the latter species. The other two species of Scomber also harbour two populations of Kuhnia each, one corresponding in size and shape of the hamuli and shape of the opisthaptor to K. scombri, the other to K. sprostonae (Figs. 3-S). However, there are many differences in relative organ sizes between populations of the two species from different geographical areas (K. scombri: Tables l-3; K. sprostonae: Tables 4-6). Differences are most clearly seen in the size of the hamuli of K. scombri (Fig. 6) and of K. sprostonae (Fig. 7). Intermediate stages were found between the two extremes of K. scombri, namely between worms from S. japonicus, Ecudador, with the largest hamuli, and from S. japonicus, Brazil, with the smallest. With respect to K. sprostonae, the population from S. scombrus in the North Sea appears to be clearly separated in the large size of the hamuli from the populations on other hosts and in other localities (Fig. 7). It is important to note that the hamuli do not increase in length with increasing size of the worms, at least in the size range examined. Regression analysis using 25 specimens of K. scombri from S. scombrus in the North Sea (0.6-3.7 mm long), 16 Matsui

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Geographical variation in Kuhniu

A Pm. 1. Distribution of Scomber juponicus (fine stipple, Atlantic and Indo-Pacific Oceans), S. scombrus (medium stipple, northern Atlantic and Mediterranean), and S. austruiusicus (coarse stipple. Pacific Ocean). l Localities at which Scomber spp. with Kuhniu scombri was collected. x Localities at which Scomber spp. with Kuhniu sprostonue were collected.

FIG+. 2. Kuhniu scombri (A) and K. sprostonue (B) from Scomber scombrus, North Sea. Whole mounts, copulatory organ, large and small genital hooks, hamuli and marginals I. Scales in ).urr. Note: Kuhnia scombri differs from K. qkostonue mainly in the clearly separated opisthaptor, the larger and differently shaped hamuli, the smaller clamps, and the posteriorly joined caeca.

572

K. ROHDEand N.

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S. JAPONICUS BRAZIL

3. Kuhnia scombri (A) and K. sprostonae (B) from Scomber japonicus, Brazil (Sao Paulo State).

worms from S. scombrus in the Mediterranean (1.82.7 mm long), and 8 worms from S. juponicus in the Mediterranean (1.1-2.4 mm long), showed that there was no significant slope within each population and when all three populations were pooled. Marginals II are rare and were examined only in some specimens of K. scombri and K. sprostonae from the North Sea. No differences were seen (Fig. 8). Both species have the same basic clamp structure. There are five sclerites, of which one-the labialeconsists, according to Mamaev (1982), of two fused sclerites (Fig. 9). Differences between the two species are a median crest of the antero-supplementarium in K. sprostonae against a median groove in K. scombri, a differently shaped medio-supplementarium, and a greater number of holes in the mediobasale of K. sprostonae. However, K. sprostonae from the North Sea resembles K. scombri more closely in the struc-

ture of the antero-supplementarium and mediosupplementarium than populations of its own species from other localities (Fig. 9, clearly visible in eight specimens). K. scombri from the North Sea has an antero-supplementarium with deeper indentations than any other form (Fig. 9, clearly visible in 10 specimens). A small connecting piece between the mediobasale and antero-supplementarium was clearly seen only in specimens of K. sprostonae from Ecuador (Fig. 10) but may also be present in populations from other localities. It is not clear whether it represents a genuine sclerite. In the length of the hamuli, populations of K. scombri on S. japonicus from different localities show the greatest variability (Fig. 1l), apparently a consequence of the wide geographical range of the host species. In the Mediterranean, a region where Scomber

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0

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S. JAF’ONICUS ECUADOR

FIG. 4. Kuhnia scombri (A) and K. sprostonae (B) from Scomberjaponicus, Ecuador.

and S. scombrus are sympatric, Kuhnia scombri from both hosts are identical in the size of the hamuli (Fig. 11) and in all other characters examined (Table 3). This is clearly shown by the cluster analysis (Fig. 13); minute differences as shown in the graph must be expected even between identical populations, because the variance of measurements is not considered in the analysis. The only possible interpretation of the analysis is that the same population of Kuhnia scombri species infects both host species. Table 3 and Fig. 13 also show that there are no differences between the populations of K. scombri in the North Sea and North America. Differences are most distinct between the populations in South East Australia (on S. australasicus), Ecuador (on S. japonicus) and all the others grouped together (on S. scombrus and S. japonicus). However, between all the populations and in all characters, intermediate’ stages are found, and separation in the cluster analysis is not according to hosts. Hence, establishment of different species or even subspecies for any of the populations would not be justified, and all three host species appear to be infected by the same species, K. scombri. Differences between populations of Kuhnia sprostonae are more distinct. K. sprostonae from

japonicus

513

Geographical variation in Kuhnia

1985

S. scombrus in the North Sea appears to be most clearly separated from the other populations, shown in-Figs. 7 and I2 for the hamuli, and in Tables 4 and 6 for the other characters. It differs in all characters from the other population except in the size of the buccal suckers, in which it is similar to the population of K. sprostonae from Ecuador (Table 6). The cluster diagram shows the differences particularly well (Fig. 13). The North Sea population differs from the others also in the structure of two of the clamp sclerites (Fig. 9). characters which are not included in the cluster analysis. Clear differences also exist between populations from Brazil (on S. japonicus) on the one hand and from Ecuador and South East Australia (on S. japonicus and S. australasicus) on the other (Fig. 13). Again, separation is not according to host species, i.e. different hosts are apparently infected with the same parasite species. With regard to microhabitats, K. scombri from most localities except Ecuador show a clear preference for the base of the gill filaments (Table 7, Figs. 14, 15). They are attached between two filaments, with the anterior ends directed towards the tips of the filaments. There also appears to be preference of some populations for attachment to the external gill filaments (Table 7). Data for K. sprostonae are sufficient only for two populations, that on S. scombrus in the North Sea, and that on S. japonicus in Brazil. Whereas the former was always found on the pseudobranchs (Fig. 14), the latter was always found on the first three gills and mainly their posterior parts (Fig. 15). An additional 30 worms of the former population on some of 400 additional fish examined were also found on the pseudobranchs.

DISCUSSION

The genus Kuhnia was established by Sproston (1945) for two species, namely K. scombri and K. minor, both from Scomber scombrus. The drawings given by her for the second species clearly indicate that she was wrong in considering it to be the same species as “Octocotyle” minor described by Goto (1894, see also Goto, 1900) from S. japonicus in Japan. Price (1961) recognized this and proposed the name K. sprostonae for it. Rohde & Watson (in press) established the new genus Pseudokuhnia for “0. ” minor. It differs from Kuhnia mainly in the presence of two dorsolateral vaginae, and differently shaped large genital hooks and opisthaptor. A historical account of Kuhnia is given by Sproston (1946); early synonyms of K. scombri are also given by Price (1961). In his discussion of the genus Kuhnia, Mamaev (1982) states that the testes are arranged in a single row; in all populations of the two species examined by us, more than one row was present. Price (1961) gives Pomatomus saltatrix (Pomatomidae) in the New York Aquarium as a host of K. scombri; this is obviously an unnatural host

K. ROHDE and

N.

I.J.P. VOL. 15. 1985

WATSON

L

0%

S.AUSTRALASICUS SE. AUSTRALIA

FIG. 5. K~n~scorn~~i

0

0

0

(A) and & spntstonae @) from ~~rn~~a~~~l~i~*

infected only under abnormal and crowded conditions. Price (l%l) established the subfamily Kuhniinae for the genera Paramazocraes, Pseudanthocotyle and Kuhnia. These genera differ in the absence or presence of a vagina, the number and structure of the genital hooks, etc., i.e. the subfamily appears to be heterogeneous. A revision of the whole family

0

(

,c New South Wales.

Mazocraeidae is necessary before the subfamily status of Kuhnia can be determined. To date, the following species have been included in the genus Kuhnia beside K. scombri, K. sprostonae (and Pseudokuhnia minor). K. macracantha (Meserve, 1938), Sproston, 1946 from unidentified mackerel at Galapagos Islands; the type (USNHC, 9177) examined by us shows that

1.49-4.33, 2.43 (13) 2.0 (1)

S. australasicus New South Wales Philippines

2.88 (11) 2.29 (35) 2.11 (3) 2.20 (20) 3.79 (3)

0.38 (9) 0.42 (9) 0.70 (6) 0.48 (11) 0.59 (4) (1)

0.16-0.73, 0.43 (13) 0.41 (1)

0*30-0*54. 0.18-0.54, 0.63-0.76, 0.37-064, 0*51-0.70, 0.49

0.67 (11) 0.55 (33) 0.43 (3) 0.51 (20) 0.76 (3)

0.036-0.052, 0.041 (10) 0.056 (1)

(9) (7) (5) (9) (4) (1)

0.073 (11) 0.067 (17) 0.053 (3) 0.064 (20) 0.057 (3)

OXt48-0~057, 0.052 0*051-OG68, 0.064 0~074-0~080, 0.077 0~058-0*071, 0.065 0~070-0*075, 0.072 0.05 1

0.058-0.081, 0*035-0~084, 0.052-0.054, 0.058-0.074, 0*055-OG61,

Buccal suckers (diameter)

0.039 0.039 0.046 0.041 0.041

(8) (6) (5) (8) (4) (1) 0~024-0~037, 0.031 (10) OGlo (1)

0~035-OGI3, 0.034-o-042, OG45-0@48, 0.037-0.050, 0.037-OTt48, 0.038

0@44-0*050, 0.046 (10) 0*038-0.050, 0.043 (11) 0.035-0.036, 0.035 (3) 0*036-0*045, 0.041 (20) 0.041 (1)

Pharynx (diameter)

TABLE I-Kuhniascombri FROMDIFFERENT HOSTSAND LOCALITIES: organs which change with body length (minimum-maximum, Diameter = (length + width)/2

Maximum width

of

0.35-0.88. 0~21-0.85, 0.42-044, 0.32-0.76, 0.70-0.82,

measurements

Body length

and

190-3.63, 0.62-3.66, 1.92-2.24, 1.77-2.72, 3.67-3.86,

body

1.49-344, 2.08 (9) 1.14240; l-86 (9) 3.8 -5.3 , 4.12 (6) 1.39-2.28, 1.85 (11) 2.65-3.22, 2.87 (4) 1.71 (1)

of

Brazil Mediterranean Japan Ecuador South Africa Argentina

S. japonicus

North America North Sea Bay of Biscay Mediterranean Guernsey

Scomber scombrus

Length

Largest clamp skeleton (diameter)

in ‘mm (number

0.039 (9) 0.048 (9) 0.053 (6) 0.077 (11) 0.056 (4) (1) 0*035-0*059, 0.043 (13) 0.039 (1)

0~035-0@43, 0+44-0~052, 0.051-0.054, OXr69-0.088, 0.054-0.059, 0.040

0~056-0.064, 0.059 (11) 0~05O-OG56, 0.056 (16) 0.051-0.056, 0.053 (3) [email protected], 0.049 (20)

mean

0.33 (9) 0.34 (5) 0.49 (6) 0.48 (11) 0.47 (3) (1) 0.25-0.42, 0.31 (13) 0.27 (1)

0.28-0.41, 0.29-O-39, 0.43-0.56, 0*41-060, 0.41-0.55, 0.30

$ 1. g. ; B’ $ g ij.

k

0.37 (19) (3)

%

(3)

0.34 0.31-0.36, 0.32-044,

0.35-O-35, 0.35

8 g

(11) 0.35 (15) 0.25-0.46,

0.35-O-58, 046

Opisthaptor (length)

measured)).

K. ROHDEand N. WATSON

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I.J.P. VOL. IS. 1985

TABLE2-Kuhnia scombri FROMDIFFERENT HOSTS ANDLOCALITIES Length in pm of structures which are independent of body length, and number of small genital hooks (minimum-maximum, mean (number measured/counted)). For hamuli see Fig. 11 Marginals I Scomber scombrus North America North Sea Bay of Biscay Mediterranean S. ja~o~jc~ Brazil Mediterranean Japan Galapagos Isl. Ecuador South Africa S. a~~ra~~icus New South Wales Philippines

24-26, 25 (15) 22-28, 25.2 (26) 24-2f624.3 $)) 20-25, 22-s (4) 23-25, 24 (3) 21-24, 22.7 (6) 21-25, 23.3 (8) 21-22, 21.5 (2) 21-24, 22.5 (21)

large genital hooks

small genital

no. of small

hooks

genital hooks

26-32, 28.8 (16) 26-30, 27.9 (9) 28 (1) 21-25, 23.4 (10)

18-23, 20 (28) 17-20, 18.6 (14j 16-21, 19 (3) 14-19, 16.8 (14)

17-22, 19.2 (10) 22-24, 22.7 (3) 22-25, 23.3 (4) 24 iii 25-28, 26.5 (11)

10-14, 12.8 (9) 14-16, 15.4 (5) 13-17, 15.4 (5) 17 (1) 16-20, 17.5 (25)

25

(I)

20-27, 23.2 (21) 20 (1)

it is a synonym of X. scombri, clearly indicated by the shape and size of the hamuli (130 m long) (see also Meserve, 1938). K. brumae (Parona & Perugia, 1896), Sproston, 1946 from Brama rayi in the Mediterranean; only tentatively included in Kuhnia by Sproston; the number of genital hooks (32) arranged in a circle indicates that it does not belong to Kuhnia. K. thunni (Ishii & Sawada, 1938), Sproston, 1946; from Thunnus orientalis in Japan; the length of the hamuli (116-125 pm) indicates that it is a synonym of K. scombri (see also figures in Price, 1961). K. brevoortia Hargis, 1955 from Brevoortia patronus, Florida; placed in genus Mazocraes by Mamaev (1982) on the basis of the differently shaped hamuli (see also Price, 1961), testes forming one whole mass, and the different host family; the holotype (USNHC 37491) examined by us shows the unusual hamuh clearly. K. singaporensis Price, 1961 from “Ikan Trubot”, Singapore; the description by Price (1961) and our examination of three cotypes (USNHC 36302) show that the ham&i differ clearly from those of K. scombri and K. sprostonae in their short handle, they are more similar to those of Pseudokuhnia minor; the species differs from P. minor in its large and small genital hooks, in the vitellaria terminating some distance anterior to the opisthaptor, and in the differently shaped opsthaptor; its status must remain uncertain, but it does not appear to be a species of Kuhnia (see also Mamaev, 1982). K. orient&is (Chauhan, 1950), Price, 1961 from Dussumieria acuta, Puri, India; the description and figures are unsatisfactory and an allocation to the genus Kuhnia can only be tentative; the length of the hamuli is given as 38-49 pm, similar to those of

14-18, 15.7 (21) 1.5 (1)

9-13, 10.9 (32) 8-12, 10.2 (37) 9-13, 10.4 (18) 10-11, l&S (4) 9-16, 9.7 (6) 9-10, 9.8 (6) 7-15, 9.8 (29) (2) 10, 10

8-11, 9.9 (20) 10 (1)

K sprostonae in the Pacific (Tripathi, 1959); Tripathi (1959) described it as Mazocraes orienta&. K. indica Tripathi, 1959 from Cybium guttatum, Orissa, India; the shape of the opisthaptor and the length of the hamuli (26-38 m) indicate that the species may be K. sprostonae, but only seven genital hooks of smaller size are said to occur; the description and figures are unsatisfactory, particularly with respect to the copulatory organ and the hamuli. K. guttatumai Gupta & Krisha, 1977, from Cybium guttatum, Orissa, India; the figures and descriptions are inadequate and do not permit ahocation to any genus; the length of the hamuli is given as 6 m, which is much less than that in any species of Kuhnia. K. micro~epidot~i Gupta & Krishna, 1977 from Scomber micro~ep~dot~ (synonym of Rastrefliger kanagurta), Orissa, India; the figure and description are inadequate and do not permit allocation of the species to any genus; the length of the hamuli is 90-150 pm, which corresponds approximately to that of Kuhnia scombri, however, the marginals I are said to be 50-80 w long, i.e. much longer than those of any species of Kuhnia. K. pricei Gupta & Krishna, 1977 from Scomber microlepidotus (synonym of Rastrelliger kanagurta), Orissa, India; the figure and description are inadequate and do not permit allocation to a genus; only two genital hooks are said to occur. K. oto~ith~ Yamaguti, 1953 from Oto~ith~ sp. (fam. Otolithidae),

Celebes;

transferred

to the genus

Tagia family Discocotylidae, by Hargis (1955, 1956) on the basis of its discocotylid clamps etc; other important differences between this species and Kuhnia spp. are the differently shaped ovary and the absence of an armed cirrus.

:

Pharynx/lenqth 1, /(length + width)/2 NSW(a)

Brazil@

Brazil(j)

NSW(al

: Brazil(i)

NSW(al

Opisthaptor/length 3, /(length + width)/2

NSW(a) Brazil(i)

Brazil(j) NSW(a) N.Sea(s)

Med(j)

Med(s)

MedCi) Med(s)

Med(s)

Jap(j) N.Sea(s)

JaJJ& ’

Med (I) ’

NSW(a)

Brazil(j)

Clamps/length 91 /(length + width)/2 Medo Med(s)

Med(s) Med(s)

MedG)

Jap(.i) Jap(j) Japo)

Ecuad NSW(a)

Brazil@ Brazil(j)

Med(s) Jap(j)

NSW(a) Med(j)

NSW(al N-Am(s)

NSW(a) NSW(a)

Brazil(j) Brazil(j)

Med(s) Ecuad

Buccal suckers/length 9, ” /(length + width)/2 :

: : :

Med(j) Jap(j)

Brazil@

No difference Brazil(j) NSW(a)

Length of small genital hooks Number of small genital hooks Body width/length

Length of hamuli Length of marginals I Length of large genital hooks NSW(a)

N.Am(s)

Japti)

JapCi)

Jap(j)

Ecuad@

EcuadQ

MedCiI

MedCj)

Japli)

N&a(s)

N.Sea(s)

N.Am(Q

N.Am(s)

N.Am(s)

N.Sea(s)

Medls)

N&a(s) EcuadQ MedCjl N.Am(s)

Ecuada

N.Sea(s)

S.AfrCi)

MedCj) N.Am(s) -) Ecuad Med(s) N&a(s)

Med(s)

N.Sea(s) N.Am(sl Med(sl Ecuado)

N.Sea(s)

JapCi)

N.Am(s)

Ecuad N.Am(s)

Ecuad

Ecuadfi)

N&a(s) N.Sea(s) Ecuad@

N.Am(s)

N&n(s)

N&a(s)

Ecuad@

3--DIFFERENCES IN MORPHOLOGICAL CHARACTERS BETWREN POPULATIONS OF Kuhnuu sc0t?lbri FROM DIFFERENT HOSTS AND LOCALITIES. a: Scomber austrulasicus,s: S. scombrus, j: S. japonicus. Jointly underlined: no significant difference (P < 0.05) using a regression analysis or analysis of variance followed by Newman-Keuls multiple range test.

TmLm

Y -4

0.98-1.86, 1.54 (10) 1.21-2.02, 160 (11)

0.82-344, 1.55 (6) 2.15~2.35, 2.25 (2)

S. japonicus Brazil Ecuador

S. australasicus New South Wales Hawaii

1-95 (18)

Body length

and measurements

0.54-534,

of body

Scomber scombrus North Sea

Length

0.28-0.73, 0.42 (6) 0.79-0.88, 0.84 (2)

0~31-060, 0.41 (10) 0.35-066, 0.49 (11)

0.26-1.49, 0.73 (18)

Maximum width

0.038-0.065, 0.054 (5) 0.079-O-080, 0.080 (2)

0.030-0.035, 0.032 (10) [email protected], 0.073 (10)

0.052-0.121, 0.089 (10)

Buccal suckers (diameter)

0.022-0.037, O-031 (5) 0.036-0.038, 0.037 (2)

0.030-0.036, 0.032 (10) 0~032-0~041, 0.035 (10)

OGl4-0@64, 0.054 (8)

Pharynx (diameter)

TABLE 4-Kuhniasprostonae FROM DIFFERENT HOSTS AND LOCALITIES: of organs which change with body length [minimum-maximum, Diameter = (length + width)/2

Largest clamp skeleton (diameter)

in mm (number

0*035-0@66, 0.044 (6) 0.050-0.054, 0.052 (2)

0~034-0~043, 0.038 (9) 0.051-0.061, 0.056 (11)

0.072-0.130, 0.106 (14)

mean

0.16-0.45, 0.24 0.21-0.24, 0.23

(6) (2)

0.15-0.22, 0.18 (10) 0.20-0.27, 0.23 (10)

0.21-0.82, 0.50 (15)

Opisthaptor (length)

measured]),

f 2 z

B z

g

.?c

Geographical variation in Kuhnia

I.J.P.VOL.15. 1985 TABLE

S-Kuhniasprostonae

579

FROM DIFFERENT HOSTS AND LOCALITIES

Length in pm of structures which are independent of body and length, and number of small genital hooks (minimum-maximum,

mean (number measured/counted)).

For hamuli see Fig. 12

Marginals I

large genital hooks

small genital hooks

North Sea

21-28, 25 (7)

23-28, 26.1 (8)

15-18, 16.6 (9)

S. japonicus Brazil Ecuador

17-20, 18 (7)

8-13, 9.8 (16) 15-19, 16.6 (7)

6- 8, 7.4 (14) 11-15, 12.5 (15)

9-11, 10 (5) 11-16, 13 (8)

S. australasicus New South Wales Hawaii

17-21, 19

13-21, 16

10-14, 11.2 (6)

10-l 1, 10.8 (4) 12 (1)

no. of small genital hooks

Scomber scombrus

(2)

‘octtocotyle” scombri described by Layman (1930) from S. japonicus in Peter the Great Bay near Vladivostok, is not K. scombri. Although the hamuli are not clearly drawn, the figure indicates that it is P. minor (see also Rohde & Watson, in press). K. scombri reported by Yamaguti (1953) from Scomber kanagunta (probably Rastrelliger kanagurta), Celebes, has a hamulus of 30 w length, no illustrations nor description are given and the species status must remain uncertain; in the length of the hamuli it corresponds to K. sprostonae rather than to K. scombri. In summary, only two species can with certainty be included in the genus Kuhnia at present, i.e. K. scrombri (synonyms K. macracantha, K. thunnt) and K. sprostonae (synonym K. indica?), both infecting Scombridae and possibly Scomber spp. only. Both species show much geographical variation in many characters, including the size of the hamuli and genital hooks. Measurements made by us failed to show that these structures change with size of the worms, at least in the size-range examined. This contradicts the statements of some authors, (according to whom the hamuli grow in adult worms). Thus, Llewellyn (1963, p. 302) writes “exceptionally, as in the polyopisthocotylinean mazocraeids (e.g. Kuhnia scombri), the hamuli continue to grow after the formation of the adult adhesive organs or clamps (see Llewellyn, 1957c)“. However, in the paper cited (Llewellyn, 1957) no reference is made to the growth of the hamuli. Sproston (1945) gives data for Kuhnia scombri and K. sprostonae, which seem to indicate a very slight growth of hamuli from a mean of approx. 100 p long in worms approx. 1.5 mm long to a mean of approx. 120 m long in worms 6.5 mm long. No statistical analysis is given, and the measurements of hamuli fall within the range for worms from the North Sea (Rohde & Watson, in press). The growth of hamuli in K. sprostonae appears to be more distinct, but only three specimens were examined. Even if a slight growth of hamuli should occur, it would be insufficient to explain the differences between populations. Clearly, there is no correlation between body

(5)

size and length of hamuli/genital hooks in either of the species (Tables 1,2,4,5, Figs. 11.12). For example, the largest K. scombri are from Japan, and their hamuli are among the smallest. With regard to body length, Finlayson (1982) observed that free-moving, freshly dead or formalinfixed K. scombri were approx. 25% shorter than attached live worms, and worms alive under a coverslip, deep frozen or dead for some time were approx. 25vo longer. This indicates that caution is necessary in taking and interpreting allometric measurements, if worms are not preserved under standard conditions. A certain standardisation was achieved in this study by firstly, measuring only worms which were not obviously distorted, secondly by calculating regressions based on both lengths of worms and average diameter ((length + width)/2), compensating for any shrinking effect (practically no differences were found, Tables 3,6). Some allometric differences between populations are so marked that they cannot be explained by different fixation (Tables 1,4, Figs. 2-5). Thus, geographical variation in both species is real, but whereas in S. scombri gradual transitions in all characters occur between the various populations clearly indicating that only a single species exists, differences between populations of K. sprostonae are much greater. In particular, the population on Scomber scombrus in the North Sea differs strongly from all the others, best illustrated by the large size of its hamuli. Nevertheless, a separate species is not established, because larger sample sizes will probably show some overlap even in the size of the hamuli (Fig. 12). More importantly, all differences are of a quantitative nature and interbreeding may occur throughout the range of the species. More samples, particularly from the Mediterranean, South Africa, and other parts of the Indo-Pacific have to be examined to clarify whether intermediate, i.e. interbreeding populations occur. Clear differences in microhabitat preferences were found between the only two populations of K. sprostonae for which sufficient data are available,

Scomber

australasicus,

: : :

Pharynx/length I, /(length + width)/2

OpisthaptorAength ,, /(length + width)/2

:

Buccal suckers/length 1, ” /(length + width)/2 :

Number of small genital hooks Body width/length

Length of small genital hooks

Clamps/length 7, /(length + width)/2

j: S. japonicus.

Ecuad@ Brazil(i) Brazil(j)

NSW(a) NSW(a)

NSW(a)_ Ecuad

Brazil(i) Brazil(j) Brazil(j)

NSW(a)

Brazil(j)

EcuadQ Ecuado

NSW(a)

Ecuado NSW(a)

Ecuad

N.Sea(s) N.Sea(s)

N.Sea(s)

N.Sea(s) N.Sea(s)

N.Sea(s)

N.Sea(s)

NSW(a)

Brazil(j)

Ecuad

N.Sea(s) N.Sea(s)

Ecuada

N.Sea(s) N.Sea(s)

NSW (a)_ Ecuad

Ecuadu NSW(a)

Brazil(j)

Ecuad@ Ecuadu

N. Sea(s)

Brazil(j) Brazil(j)

Ecuad@ N. Sea(s) NSW(a) NSW(a)

Brazil(j) Brazil(j) -Brazil(j) Brazil(jJ

FROM

DIFFERENT

Jointly underlined: no significant difference (P < 0.05) using a

sprostonae

analysis or analysis of variance followed by Newman-Keuls multiple range test

s: S. scombrus,

Length of hamuli Length of marginals I Length of large genital hooks

a:

LOCALITIES

TABLE ~-DIFFERENCES IN MORPHOLOOKALCHARACTERSBETWEEN POPULATIONS OF Kuhnia

AND

regression

HOSTS

I.J.P. VOL.15. 1985

581

Geographical variation in Kuhniu

SCOMBER JAPONlCUS ECUADOR

S.SCOMBRUS

SJAPONICUS

S.AUSTRAL.

NORTH SEA N. AMERICA

JAPAN

S.E AUSTRALIA

SJAPONICUS BRA21 L

FIG. 6. Hamuli of Kuhniu scombri from different hosts and localities.

100

I-

__________________________-_____----_____-----_-------

r7

5

50 _______.__.__-__-_______---_---------_-_-__------------.

0

S. SCOMBRUS NORTH SEA

S.JAf? ECUADOR

S.AUSTR. S JAI? S.E.AUSTR BRAZIL

FIG. 7. Hamuli of Kuhniusprostonue from different hosts and localities.

20

E a

20

_-

--

--

---

L_

----

lLc!Li!L LJii4.L _---

-

FIG. 8. Marginals II of Kuhnia scombri (top) and K. sprostonae (bottom) from Scomber scombus at

Helgoland, North Sea.

582

K.

ROHDE and N. WATSON

I.J.P. VOL. 15. 1985

a

e

0 00

00 00

00 00

Fro. 9. Clamp sclerites of Kuhnia scombri (left) and K. sptwstonue (right). a, arcuatum anterius; b, anterosupplementarium; c, postero-supplementarium fused with arcuatum posterius (= labiale); d, mediosupplementarium; e, mediobasale. H, specimens from Helgoland, North Sea. Optical sections in left and right columns. i.e. between those from the North Sea and Brazil (Figs. 14, 15); and between the populations of K. scombri from Ecuador and all other localities

Sea (Table 7, see also Rohde, 1980). Ktari (unpublished, D.Sc. Nat. Thesis, Academic de Montpellier, Universite des Sciences et Techniques du Languedoc,

(Table 7). However, although many specimens were found in Ecuador, they were from only three fish; more data are needed to verify the results. Most populations of K. scrombri appear to prefer the external gill filaments, except that from the North

1971) recovered 37 K. scombri from the first gill of S. scombrus in Tunisia and two from the second, and all were attached to the external filaments. He examined over 100 fish, but does not state how many fish were infected. Although his data seem to indicate that the microhabitat of the parasite is narrower than that in the North Sea, with a clear preference for the external filaments, caution is necessary in accepting the findings in view of the lack of information on the number of fish infected. Matsui’s (1967) review of the genus Scomber permits a comparison of speciation of hosts and parasites. S. scombrus differs strongly from the other two species, S. japonicus and S. australasicus (which are sometimes put in a separate genus, Pneumatophorus), in having more heavily ossified bones, no swimbladder and the first haemal spine anterior to

FIO. 10. Clamp of Kuhn& sprostonae, Ecuador, showing connecting piece (arrow) between mediobasale and antero-

supplementarium.

I.J.P.

VOL.

15. 1985

Geographical variation in Kuhnia

Is_

583

S. australasicus S.E. AUSTRALIA

IO-

S-

PMUPPINES I

n

m

,

,

mN.Z.

I

ECUAm

_iL-

N. SEl

IS-

N.AMERICA

IO-

s-

I i-l ‘IIS-1201121-125 ‘129-l30’131-I35 ‘l35-WO’Wl-145’

LENGTH

OF LARGE

HAMULI

(Tim)

Fro. 11. Length of hamuli of Kuhniuscombri from different hosts and localities.

n BRAZIL

rJI

IO

z P

k 6 i 2

i 5-

ECUADOR

S.E.

N. SEA

AlJSlRAJJA n ‘31-35

’ 36-40

’ 41-45

‘46-50

LENGTH

‘51-55

’ M-60

’ 61-65

OF LARGE HAMULI

fa ’ 66-70

’ 71-75

II ’ 76-60

61-65

’

(pm)

FIG. 12. Length of hamuli of Kuhniu sprostonoe from different hosts and localities. Brazil and Ecuador:

Scomber japonicus, S.E. Australia: S, australsicus, North Sea: S. scombrus. the first interhaemal bone, etc. A markedly different population of K. sprostonae on S. scombrus corresponds to these morphological differences. Matsui (1967) distinguishes different populations of S. japonicus, namely one in the Western Atlantic (North America-Argentina), one in the Eastern Atlantic (Mediterranean-South Africa), and one in the Pacific (China-California-Chile). There are

corresponding differences between the populations of K. sprostonae from the Pacific (on S. japonicus and S. australasicus) and the western Atlantic (on S. japonicus). Populations of K. scombri in the Pacific also segregate clearly from those in the Atlantic except for the population in Japan, of which only a few specimens were examined. Differences between populations in the Eastern and Western

I.J.P. VOL. 15. 1985

K. ROHDEand N. WATSON

584

Kuhnia scombri

Kuhnia sprostonoe

FIG. 13. Cluster diagram showing similarities of Kuhniu scombri

and K. sprostonue from different hosts and localities. Analysis based on length of large genital hooks, length of genital hooks, number of small genital hooks (no differences), length of hamuli, shape of hamuli, length of marginals I, shape of opisthaptor; regressions width/length of body, clamp diameter/diameter [(length plus max. width)/21 of body, buccal suckers/diameter of body, opisthaptor diameter/diameter of body, pharynx diameter/ diameter of body. Note: differences between regressions were almost identical when diameter of body was replaced by length. Shape of clamp not included in analysis. Ordinate: an arbitrary scale of similarity (Burr, 1968, 1970). TABLE ‘I-DISTRIBUTION OF Kuhnia scombri ON THE GILLS

Host species, locality (no. examined/no. infected) S. scombrus, North Sea (85/57)

,t

9, S. 1, 0 ,, 9,

3,

North America (7/6) 3, Mediterranean (14/S) Juponicus, Mediterranean (9/2) 9, South Africa (6/l) ,, Brazil (98/30) 9, Japan (10/l) 9, Ecuador (3/3)

S. australasicus, NSW (229/22)

I 99 51 18 6 4 13 0

36

No. on gills II III 67 36 3 1 2 17 7

7

Atlantic on S: japonicus are less clear, and there is no clear segregation according to host species, i.e. parasites appear to be freely exchanged between hosts where they are sympatric, and parasites on different host species have undergone joined evolution.

11 1 0 0 0 9 0

0

IV 0 0 0 0 0 3 0

0

No. on filaments External Internal 63 11 23 5 2 28 7

33

70

2 0 2 4 6 0

Base of ,, 1, I, I, 11 ,,

filaments ,, 9, ,1 ,, ,, ,, ,, 0 ,, I, ,, 1,

~ 1

Not restricted to base of filaments Base of filaments

A certain amount of correspondence in the degree of segregation of hosts and parasites does not permit the conclusion that coevolution has occurred in the sense that differences between parasite populations are adaptations to different host populations, although this may perhaps be the case for certain

I.J.P.voL.15. 1985

2CM

l-

585

Geographical variation in Kuhnia

I

2CM

SCOMBER

JAPONICUS BRAZIL

N. SEA

FOG.14. Distribution of Kuhnia scombri and K. sprostonue on 85 Scomber scombrus (57 infected with at least 1 species) from Helgoland, North Sea. x , Kuhnia sprostonrre; a,10 K. scombri; l , 1 K. scombri; P, pseudobranch; EXT. external gill filaments; INT, internal gill filaments.

characters (e.g. differences in attachment organs which may correspond to differences in gill filaments). Clearly, differences in the size of the genital

hooks are not likely to be such host adaptations; they probably have evolved randomly with greatest differences occurring between those ~pulations which have been separated longest. The data also permit the conclusion that populations of Scomber on the West and East coasts of South America have been separated for a long time. Their populations of K. scombri and K. sprostonae are clearly different.

Fro. 15. ~st~bution of Kuhnia scombri and K. ~~tonae on 98 Scomber japonicus from Sao Paulo State, Brazil. x , Kuhn& sprostonae; 0, 1 K. scombri. P, pseudobranch, EXT, external gill filaments; INT, internal gill filaments.

Acknowledgements-This work was supported by grants from Australian Biological Resources Study and Australian Research Grants Committee. Dr. B. B. Collette, Systematics Laboratory, National Museum of Natural History, Washington, D.C. kindly identified and lent specimens of Scomber spp. from many localities; work at Helgoland was supported by Biologische Anstalt Helgoland; in Brazil, help was provided by Dr. Moreira, institute Gceanografico, Sao Paulo, and in Argentina by Dr. Bastida and Dr. Angelescu, lnstituto Investigation y Desarrollo Pesquero, Mar de1 Plata. Dr. D. Gibson, British Museum (Natural History) kindly lent specimens of Kuhnia scombri from Guernsey and the Bay of Biscay; Dr. Ralph Lichtenfels, U.S. National Helminth Collection, Beltsville. lent types of Kuhnia ~acracantha, 1% bre~oortia and K. singaporensis; Dr. B. Jones, Fisheries Research Division, M.A.F., Wellington, donated specimens of Kuhnia scombri from Golden Bay, New Zealand. I am grateful to members of the Fish. Cooperative, Ulladulla, for catching fish in Jervis Bay. R. Hobbs, UNE, helped with the statistical analysis.

586

K. ROHDEan d N. WATSON REFERENCES

BURRE. J. 1968. Cluster sorting with mixed character types 1. Standardization of character values. Australian Computer Journal 1: 91-99. BURR E. J. 1970. Cluster sorting with mixed character types II. Fusion strategies. Australian Computer Journal 2: 98-103. CHAUHANB. S. 1950. Trematodes from Indian marine fishes. Part VI. Monogenetic parasites of the family Mazocraeidae (Diclidophoroidea): Description of a new species of the genus Mazocraes Hermann, 1782. Records of the Indian Museum 48: 5 l-53. COLLETTEB. B. & NAUEN C. E. 1983. FAO Species Catalogue. Vol. 2. Scombrids of the World. United Nations Development Programme. Food and Agriculture Organization of the United Nations, Rome. FINLAYSON J. E. 1982. The alleged alternation of sexual phases in Kuhnia scombri, a monogenean of Scomber scombrus. Parasitology 84: 303-3 11. GOTO S. 1894. Studies on the ectoparasitic trematodes of Japan. Journal of the College of Science, Imperial University of Tokyo, Japan 8: l-273. GOT0 S. 1900. Notes on some exotic species of ectoparasitic trematodes. Journal of the College of Science, Imperial University of Tokyo, Japan 12: 263-295. C&PTAS. P. & KRISHNA1977. Monogenetic trematodes of fishes. On three new species of the genus Kuhnia Sproston, 1945 from marine fishes of Puri, Orissa. Indian Journal of Helminthology 29: 33-41. HARGISW. J. JR. 1955. Monogenetic trematodes of Gulf of Mexico fishes. Part VI. The suoerfamilies Polvstomatoidea Price, 1936 and Diclidophoroidea Price, 1936. Transactions of the American Microscopical Society 74: 361-317. HARGISW. J. JR. 1956. Monogenetic trematodes of Gulf of Mexico fishes. Part VIII. The superfamily Diclidophoroidea Price, 1936. (Continued). Proceedings of the HelminthologicalSociety of Washington 23: 5-13. ISHII N. & SAWADAT. 1938. Studies on the ectoparasitic trematodes. Livro Jubilar pro Prof. Travassos, Rio de Janeiro, Brazil III: 23 l-243. LAYMANE. M. 1930. [Parasitic worms from the fishes of Peter the Great Bay.] Izvestiya Tikhookeanskoi Nauchno-Promislovoi Stantzii, Vladivostok, 6: I-120 (in Russian). LLEWELLYN J. 1957. The mechanism of the attachment of Kuhnia scombri (Kuhn, 1829) (Trematoda : Monogenea) to the gills of its host Scomber scombrus L. including a

I.J.P. VOL.15. 1985

note on the taxonomy of the parasite. Parasitology 47: 30-39. LLEWELLYNJ. 1963. Larvae and larval development of monogeneans. Advances in Parasitology 1: 287-326. MAMAEVYu. L. 1982. Notes on the systematics of mazocraeid monogeneans with a redescription of some poorly studied taxa. Helminthologia 19: 25-39. MATSUIT. 1967. Review of the mackerel genera Scomber and Rastrelliger with description of a new species of Rastrelliger. Copeia 1%7(l): 71-83. MAYRE., LINSLEYE. & USINGERR. L. 1953. Methods and Principles of Systematic Zoology. McGraw-Hill, New York, Toronto, London. MESERVE F. G. 1938. Some monogenetic trematodes from the Galapagos Islands and the neighboring Pacific. Allan Hancock Pacific Expedition, Report 2: 30-89. PARONAC. & PERUCIAA. 1896. Sopra due nuove specie di trematodi parasitti delle branchie de1 Brama rayi. Atti della Societa liguistica di scienze naturali e geografiche 7: 135-138. PRICE E. W. 1961. North American monogenetic trematodes. IX. The families Mazocraeidae and Plectanocotylidae. Proceedings of the Biological Society of Washington 74: 127-156. ROHDE K. 1980. Comparative studies on microhabitat utilization by ectoparasites of some marine fishes from the North Sea and Papua New Guinea. Zoologischer Anzeiger 204: 27-63. ROHDE K. & WATSONN. In press. Morphology and geographical variation of Pseudokuhnia minor n.g., n. comb. (Monogenea Polyopisthocotylea). International Journalfor Parasitology. SPROSTON, N. G. 1945. The genus Kuhnia ng. (Trematoda: Monogenea). An examination of the value of ‘some specific characters, including factors of relative growth. Parasitology 36: 176-190. SPROSTONN. G. 1946. A synopsis of monogenetic trematodes. Transactions of the Zoological Society 25: 185-599. TRIPATHIY. R. 1959. Monogenetic trematodes from fishes of India. Indian Journal of Helminthology 1957, 9: l-149. YAMAGUTI, S. 1953. Parasitic worms mainly from Celebes. Part 2. Monogenetic trematodes of fishes. Acta Medicinae Okayama 8: 203-256. YAMAGUTI S. 1963 Systema Helminthum. IV. Monogenea andAspidocotylea. Interscience, New York, London.