Epicarids (Isopoda) of Eniwetok Atoll'

CHARLES G. DANFORTH2

Bopyrella tbomsonl mulensis n. ssp.Bopyrella tbomsoni Bonnier 1900, pp. 347­

351Fig. 1

Notopbryxus globularis (dajid) from the"North Pacific" (Sars, 1885, p. 220)

Scyracepon hawaiiensis from Hawaii (Richard­son, 1911, p . 645)

Scyracepon oceanicum from Palau (Shiino,1942, pp. 450-452)

Zonopbryxus retrodens (dajid) from Hawaii(Richardson, 1904, p. 679)

With the aid of an Atomic Energy Com­mission grant administered by Dr. R. W. Hiattof the University of Hawaii , the writer wasable to spend some time at the Eniwetok Ma­rine Biological Laboratory during the summer of1964. Despite the fact that hundreds of craband shrimp were studied, no isopod parasiteswere found. In subsequent years Dr. J. W.Knudsen of Pacific Lutheran University, in­vestigating the crustaceans of the atoll underNational Science Foundation grant GB-2412,found evidence of parasitism in several crabsand shrimp from three different islands, plusone infested crab (Phymodius) in the museumcollection. These hosts were kindly relayed tome through Dr. J. S. Garth of the Allan Han­cock Foundation at the University of SouthernCalifornia, and they disclosed the followingisopods: Bopyrella thomsoni muiensis n. ssp.,Cancricepon garthi n. sp., Gigantione prattiDanforth, Grapsicepon sp., M erocepon knud­seni n. sp., and Scyracepon hawaiiensis Richard­son.

Although all of the foregoing are membersof the Bopyridae, the title of this article waschosen to encompass the entire suborder, withthe expectation of finding members of the otherfamilies at Eniwetok Atoll, which will be in­cluded in subsequent articles under the sametitle.

1 Manuscript received November 18, 1969.23612 Angelus Avenue, Glendale, California 91208.

462

THE COLLECTING of parasitIC isopods in theEpicaridea suborder has not been intensive inthe north central Pacific, even though manyforms have been reported from the borderingcontinents and major islands. It is therefore tobe expected that additional representatives ofthe four included families (Bopyridae, Crypto­niscidae, Dajidae, and Entoniscidae) will soonbe discovered in Oceania.

The following list gives those epicarids sofar described from North Pacific oceanic is­lands (forms not identified by family arebopyrids; there are no entoniscids) :

Aporobopyrosa pacifica from Palau (Shiino,1942, pp. 441-443)

Aporobopyms ryukyuensis from Palau (Shiino,1942, p. 441)

Bopyrina andamanica from Palau (Shiino, 1939,p. 597)

Bop yrina miyakei from Palau (Shiino, 1942, pp.438- 440)

Cabirops tuberculatus (cryptoniscid) from Palau(Shiino, 1942, pp. 453-457)

Cryptione elongata from the Galapagos (Han­sen, 1897, p. 112)

Dactylocepon palaoensis from Palau (Shiino,1942, pp. 445-447)

Entopbilus omnitectus from Hawaii (Richard­son, 1904, p. 681)

Faba glabra (cryptoniscid) from Hawaii (Nier­strasz and Brender aBrandis, 1931, p. 3)

Gigantione hawaiiensis from Hawaii (Danforth,1967, p. 153)

Gigantione pratti from Eniwetok (Danforth,1967, p. 147)

Grapsicepon micronesianum from Palau(Shiino, 1942, pp. 447-450)

lonella [a new species from Hawaii, submittedfor publication]

M erocepon xanthi from Palau (Shiino, 1942,p. 444)

Epicarids of Eniwetok-DANFORTH 463

DESCRIPTION:

Female: Color yellowish in preservative, withirregularly placed brown edging on parts ofthe thorax. Specimen no. 1: 11.0 mm long and6.5 mm wide. Specimen no. 2: 13.0 mm by9.0 mm .

Head . No velum. Totally fused to thoraco­mere I, with minor notches at lateral junctions.Eyes present but small.

Thorax. Six clearly defined segments, with­out bosses or inter-segmental folds. Very nar­row coxal plates on thoracomeres I-IV of bothsides, those of I giving evidence of the fusionof I and the cephalon. Dorsum smooth andflat. Marsupium widely open, with 5 pairs ofsmall oostegites. Oostegite I with exposed,large, posterolateral incurving projection . Sevenpairs of pereopods.

Abdomen . Totally fused, with no evidence ofsegmentation, even peripherally. Five pairs ofbiramous pleopods, I being rectangular, large,and meeting its counterpart at the midline; 11­V oval and progressively smaller. Endopoditesand exopodites essentially the same structureand size, each with a midlongitudinal chitinousvein along which it is slightly folded . The ven­tral pleon shows an anterior, transverse, crenu­lated ridge, followed by 4 central, lambda­shaped elevations from which the pleopodsarise. Just medioventral to the border of theabdomen are 5 (on the long side) and 3-4(short side) , squared projections . The functionof these is not known.

M ale: Light yellow color in preservative. Pig­ment spots on head, ventral thoracomere VII,and ventral pleon. Specimen no. 1: 2.5 mm longand 1.0 mm wide. Specimen no. 2 : 3.3 mm by1.2 mm.

Head . Fused to thoracomere I and deeply im­bedded in it. Eyes very evident. Antennae notvisible from the dorsal aspect.

Thorax. Six clearly defined segments, allthe same width. Seven pairs of pereopods. Sevenmidventral tubercles.

FIG. 1. Bopyrella thomsoni muiensis n. ssp. a, b,Dorsal and ventral aspects of female; c, dorsal aspectof male; d, enlarged ventral pleon of female.

B

o

A

c

Abdomen. Six segments, separated laterallyand fused medially. Pleomeres arranged in afan shape rather than transversely, with VIsmall, central and cordate. Pleomere I the wid­est part of the animal. Ventral pleon withoutpleopods and with a smooth elevation centrallyon pleomere I. One male showed very faintlateral swellings on pleomere I; these were miss­ing on the other specimen.

REMARKS: Specimen no. 1 was taken from theright gill chamber of the female host, andspecimen no. 2 from the left gill chamber ofthe male host. They agree in general with Bon­nier's original description of both genus andspecies. However, a subspecies is proposed in­asmuch as there are several points of dissimi­larity which coincide with the differences men­tioned by Chopra (1923, pp. 469-470) for aBopyrella tbomsoni from the Andaman Islands.

Size discrepancy is immediately evident; Bon­nier's original specimens were 2.5 mm for thefemale, and 0.7 mm for the male, while theMui Island females are 11.0 and 13.0 mm, andthe males 2.5 and 3.3 mm. Some variation

Two pairs of bopyrids.Alpbeus strenuus Dana, male and

female.Station 193, Henry (Mui) Is­

land .12 August 1966.DATE:

AREA :

MATERIAL :HOSTS:

464 PACIFIC SCIENCE, Vol. 24, October 1970

TABLE 1

C OM PARISON OF B ON N IE R'S F ORM AN D MUI IS LAND FORM OF Bopyrella tbomsoni

FORM

F EATURE

~ head

~ thorax

~ pleon

J thoraxJ pleon

Bonnier's

N o eyes, Fused to thoracomere I, but withobvious transverse fur row.Coxal plates on thoracomeres I-II of longside.Ventr al aspect with 6 transverse, crenulatedridges.

Rudimentary pleural lamellae with flat lateralfaces on larges t units. Biramous pleopodsappear as mere ovals. Pleopods I much largerthan the others, but same shape.

Progressively widening posteriorly.4 pleopods. Pleomere VI square, sing le.Transverse vent ral ridges .

Mu i Island

Small eyes. Completely fused with thoraco­mere I, only notches at periphery.Coxal plates on thoracomeres I-IV of bothsides.Ventr al aspect with 1 transverse, crenulatedridge, plus 4 midventra l " lambda-shaped"structures .Rudimentary pleural lamellae wi th concavityon lateral faces of the largest. Biramous pleo­pods with lengthwise chitinous ridge on boththe endo- and exopodites. Pleopods I elon­gate, meeting at midline.Same width for all 7 segments.N o pleopods. Pleomere VI corda te. Ventralaspect smooth, except for a central elevationon 1.

DESCRIPTION :

Female: From left branchial area of the host.Yellow-white in preservative. N o pigment spots.Body twisted slightly to the right. Very globose,with many eggs. 2.5 mm long by 2.0 mm wide.

H ead. Wide velum at both anteri or and lat­eral regions of the squarish head. Large evidenteyes. No antennae or mouth parts visible fromthe dorsal aspect.

Thorax. Concave dorsally, due to the swollenmarsup ium. Seven thoracomeres, 7 pairs ofstrong pereopods. Four pairs of pleural bosses(first pair minute) and 4 pair s of coxal plates onsegments I-IV. The former slightly rugose, thelatter definitely more yellow than the remainderof the thorax. Pleural boss on the left side ofIV with an apparent abnormality, as it is dis­placed mediall y; also, the left side of thora co­mere V with an abnormal bifurcation, Thoraco­mere IV with a small middors al swelling, Vwith a larger swelling, VI with a pronouncedand square-topped protuberance, and VII witha definite spine which is noncontiguous withthe elevation on segment VI.

Abdomen. Six segments, I-V each with apair of short pleural lamellae ( the longest 0.5mm) that are digitate, plus 2 pairs of biramouspleopods. The exopodites of the pleopods are

should be expected in any specimen study, butsince Chopra's And aman Island form and theMui Island forms tend to agree, the holotypemust be the variant-hence the erection of asubspecies. Some of the contrasting featuresare given in Table 1.

The original specimen described by Bonniercame from the Tonga (Friendly) Isles andfrom the same host genus as the ones from MuiIsland and the Andamans. Although there areover a dozen species of Bopyrella known fromvarious parts of the world , B. th omsoni is theonly form which has smooth borders on bothsides of the pleon. As far as can be ascertained,the presence in the female B. thomsoni of ab­dominal subpleural-plate processes (the "rudi­mentary pleural lamellae" of Bonnier) isunique.

The specimen no. 1 subspecies female holo­type and male allotype are deposited with theAllan H ancock Foundation collection as catalognumber 664 and 664a, respectively.

I am indebted to Dr. A. H. Banner of theUni versity of Hawai i for the identification of thehost shrimp.

Cancricepon garthi n. sp.Cancricepon Giard and Bonnier 1887, p. 172

Fig. 2

MATERIAL : One pair of bopyrids.HOST : Dacryopilumnus eremita N obili.

AREA:

DATE:

Station 406, Fred (Eniwetok)Island.

8 August 1967.

Epicarids of Eniwetok-DANFORTH 465

FIG. 2. Cancricepon garthi n. sp. a, Lateral aspectof female ; b, dorsal aspect of female , pleon removed;c, ventral aspect of male, eyes showing through c~ph­

alon all per eopods removed ; d, ventral aspect, rightappendag es of female pleomere II , showing large plateand tubercular pleopod endopodite .

similar in appearance to the pleural plates, ex­cept that they become more lobed than digitateposteriorly. Endopodites inconspicuou~ swell­ings or bulbiike structures. Uropods untra~ous,

similar to pleural plates in appearance, relativelyshort. N o middorsal elevations on pleon.

M ale : Yellowish color in preservative. Pig­ment spots scattered on dorsal thorax and dor­sal pleomeres. 1.0 mm by 0.25 mm.

Head. Small, with rounded anterior border.Antennae visible from dorsal aspect. Eyes evi­dent from both dorsal and ventral sides.

Thorax. Seven clearly defined segments,lateral portions noncontiguous. Seven pairs typi­cal pereopods. Thoracomere I separated fromcephalon by shallow furrow . Midventral tuber-cles present on segments I-VII. . .

Abdomen. Six segments, the last with a mid­posterior point. Ventral pleon showing .1 obvi­ous and 2 less evident midventral swellings onpleomeres I-III, respectively. Five pairs pleo­pods represented by slight mounds laterally onI-V.

REMARKS: The genus Cancricepon has beenderived from Cepon, and there is some confu­sion concerning several critical features. Duver-

noy ( 1840, pp . 598-603 ) referred to K epontypltS in which the endopod ites of the pleopodswere not well developed in the female. LaterNobili (1905 , p. 506) indicated that the en­dopodites were well developed. This assumptionwas also made by Bonnier (1900 , p. 251) whenhe stated that the endopodite and exopodite ofboth Cepon and Portunicepon were essentiallythe same size. Giard (19 06, p. 704) designatedGrapsicepon as the genus of a specimen thatwas probably Cepon typltS, which added to theconfusion since Grapsicepon has rudimentaryendopodites plus middorsal thoracic protuber­ances (which are not present in Cepon). Ceponelegans Giard and Bonnier (1886, pp. 889­892) was changed to Cancricepon elegans Giardand Bonnier (188 7, p. 73), and was illustrated(Giard and Bonnier, 1887, pl . 1) as havingsmall, f1aplike endopodites. Thus, while theredoes not seem to be any problem about thegenus of the specimen at hand, there definitelyshould be clarification of the "cepon" criteria.

Cancricepon is characterized by having 4middorsal elevations on thoracomeres IV-VII,which would be adequate for recognition wereit not for the fact that the words "elevation,boss, upheaval, spine, protuberance," are relativeterms.

The two previously known species of Cancri­cepon are from the shores of France. C. eleganswas described from the Straits of Dover, para­sitizing Pilumnus birtellus Linne, while thesimilar Cancricepon pi/ fda Giard and Bonnier(1887, p. 73) was originally reported fromConcarneau, France, on X anth o floridus Mon­tagu and X. incises (Leach) . Bourdon (1963,pp. 425- 426) listed the two species from thesame respective hosts at Roscoff (Brittany) ,France. Stebbing (1910 , p. 116) mentioned a"Cancricepon sp." on Pilumnus longicornis Hil­gendorf from Amirante (Seychelles area) .Otherwise the genus has been but rarely en­countered.

The length of Cancricepon elegans was givenfor the female as 9.0 mm, while the length ofC. garthi is at most 2.5 mm. The "pebbled" ap­pearance of the coxal plates and/or pleuralbosses, so much stressed by Duvernoy for Ceponand by Nobili (1905, p. 505) for Lobocepon,is slightly present in Cancricepon garthi,whereas this feature is totally absent in C. ele­gans. In the tabulated comparison between C.

B

oc

A

466 PACIFIC SCIENCE, Vol. 24, October 1970

TABLE 2

COMPARISON OF Cancricepon elegans WITH C. gartbi

FEATURE Cancricepon elegans Cancricepon garthi

Cj! head

Cj! thorax

Cj! pleon

& pleon

Bilobed. Small. Velum moderately large.

Thoracomere I with obvious pleural boss.Pleural bosses with smooth, oval surface.Coxal plates smaller than pleural bosses, par­tially hidden. Middorsal projections sharp­tipped on V-VII.All pleural plates with tubercular, rather thandigitate edges. Exopodites and pleural platesabout the same size and structure. Endopo­dites spade-shaped.

One midventral swelling on pleomere I, ornone at all on pleomeres.

N ot bilobed. Large. Velum very large, makinga hood around the cephalon.Pleur al boss of thoracomere I small or miss­ing. Pleural bosses with pebbled, circularsurface. Coxal pla tes large and very obvious.Middorsal projections sharp-tipped only onVII .Anterior pleural plates with digitate, pos­terior plates with tubercular, edges. Exopo­dites shor ter, more narrow than correspond­ing pleural plates. Endopodites merely swollenovals.3 midventral swellings on pleomeres I-III.

Thi s form was found in the left branchial

Gigantione pratti Danforth

Gigantione pratti Danforth 1967, pp . 147­149

elegans and C. garthi (Table 2), no attempthas been made to include C. pi/uta. At no placein the articles by Giard and Bonnier is a cleardistinction made between C. e/egans and C.pi/uta-indeed, Mouchet (1932, p. 505) wrote,"Giard et Bonnier n'en ont pas donne unediagnose precise, mais il est evident qu'il doit yavoir une tres grande ressemblance... ." Evenwhere the males of C. e/egans and C. pi/Ida areshown (Gi ard and Bonnier, 1887, pl. 2), theredoes not seem to be any major difference. Henceit must be assumed that subsequent referencesin the literature to C. pi/uta in France are basedupon the host being a X anth o, rather than uponstudy of the parasite.

The bopyrid pair has been deposited with theAllan Hancock Foundat ion collection, as femaleholotype no. 671, and male allotype no. 671a.

N amed in honor of Dr. J. S. Garth of theUniversity of Southern California, who has cour­teously borne with my procrastination in deter­mining epicarid identifications.

GrapsiceponGrapsicepon Giard and Bonnier 1887, p. 69

Fig. 3

Female bopyrid, immature.T rapezia specioss Dana.Station 63, Fred (Eniwetok) Is­

land.17 March 1965.

MATERIAL:

HOST :

AREA :

DATE:

cavity of the host. It has been described andsketched in the indicated reference, and is theonly one of the Eniwetok Atoll parastic isopodsso far discovered which was not collected in thefield by Dr. Knudsen . The female holotype iscatalog no. 110191, and the male allotype isno. 110190, in the U.S. National Museum.

DESCRIPTION :

Female: From the right gill chamber of thehost. Almost white in the preservative. Minutepigment streaks on thoracomeres II, III. Bodytwisted strongly to the left. Length, excludinguropods, 2.6 mm; width 1.0 mm.

Head. Square in outline, having a widevelum on the anterior and lateral borders.Velum widest posterolaterally, giving a triangu­lar shape to the cephalon . Eyes very evident, atextreme borders of the head proper. No an­tennae visible from the dorsal aspect.

Tho rax. Seven clearly indicated segments,still retaining the juvenile condition of widelyseparated pleura. No evident pleural bosses orcostal plates. Thoracomeres VI-VII with smallbut obvious posteriorly directed hooks mid-

One pair of bopyrids.Pb vmodius ungu/atus (Milne-

Edwards) .Bruce (Aniyaanii) Island.23 February 1957.A. H. Banner.

AREA :

DATE :

COLLECTOR :

MATERIAL :

HO ST :

Epicarids of Eniwetok-DANFORTH 467

M eroc epon knudseni n. sp.Merocepon Richardson 1910, pp. 33-34

Fig. 4

c

MATERIAL :HOST:

AREA :

DATE:

One pair of bopyrids.Eriphia sebana (Shaw and Nod­

der) .Station II, Fred (Eniwetok) Is­

land.5 February 1965.

AFIG. 3. Grapsicepon sp. a, Dorsal aspect of fe­

male; b, profile of dorsum, thoracomere VII indicatedby "X" ; c, ventral aspect, left appendages of femalepleomere I, with reduced endopodite.

dorsally. Seven pairs of strong pereopods. Mar­supium bordered by 5 pairs of small, cordateoostegites, widely separated and not flexed medi­ally.

Abdomen. Six segments clearly delineated butwith V-VI minute. Slight middorsal elevationson pleomeres I-III. A pair of elongated tubercu­lated plates on pleomeres I-V. Uniramous uro­pods 0.5 mm long, similar in appearance to thelateral plates; recurved. Five pairs of biramouspleopods, the exopodites slightly shorter than,and similar in appearance to, the lateral plates;endopodites as small swellings.

Male : No male was found.

REMARKS: Ergyne, Grapsicepon, Paracepon,Portunicepon, and T ylocepon all have pro­nounced elevations on thoracomeres VI-VII inthe middorsal area- the "dorsal tubercle absent"given for Portunicepon by George (1946, p.389) apparently was an error. Tylocepon canbe discounted because its spine on VI is trifid;Portunicepon and Ergyne can be discountedsince they both have well-developed endopoditeson the pleopods; and Paracepon can be dis­counted since its pleural plate borders are notdigitated or tuberculated.

There are seven species of Grapsicepon re­ported for the world, and the discovery of arepresentative, mature pair of this Fred Islandbopyrid would be important in determiningwhether the Eniwetok form is a new species,or merely an immature form of the neighboringJapanese G. magnum and G. rotundnm (Shiino,1936a, pp . 167- 172), or of the Palau G. micro­nesianum (Shiino, 1942, pp . 447-450) .

DESCRIPTION:

Female : Found in the right branchial cham­ber of the host crab. Light yellow color in pre­servative. No pigment spots. Body slightlytwisted to the left. Pronounced costate appear­ance to the dorsum. Length 18.0 mm to telson,width 10.0 mm at thoracomere IV.

Head. Strongly bilobed. An obvious velumalong the anterior and lateral borders, widestlaterally. Each cephalic lobe almost an ellipse.No eyes. Antennae not visible from the dorsalaspect. Oral cone hidden ventrally by the swol­len marsupium.

Thorax. Seven clearly delineated segments,the first 4 with greatly swollen pleural bosses,each constricted so as to produce 4 obviousswellings per thoracomere. Last 3 segments eachwith only a reduced, single swelling laterally.Coxal plates on first 4 thoracomeres, each beinga swelling only slightly smaller than its accom­panying pleural boss. A middorsal swelling onsegment V; a larger, similar swelling on segmentVI with a soft posterior bulge; a middorsal,posterior-facing, definite hook on segment VII.Seven pairs of strong pereopods. High, com­pletely covered marsupium, having the fifth pairof oostegites turgid and moved posteriad fromthe balance of the incubatory plates.

Abdomen. Length 4.0 mm. Six obvious seg­ments; I-V with a pair each of pinnate lamellaewhich slightly decrease in length posteriorly.Plate I is 6.5 mm long on the right (larger)side, 5.5 mm on the left side. Each lamella hasdefinite knob-shaped tuberosities along one edge,and strong irregularities on the other. Five pairsof biramous pleopods, the endopodites presentas irregular or oval swellings. Exopodites verysimilar in appearance and size to the lamellae ofthe corresponding pleomeres. Lengths of the leftexopodites: I = 5.0 mm, II = 4.0 mm, III =

468 PACIFIC SCIENCE, Vol. 24, October 1970

FIG. 4. Merocepon knudsen i n. sp. a, Dorsal as­pect of female; b, ventral aspect of male, showing rightpereopods I-II only; c, uropods of female ; d, ventralaspect, left appendag es of female pleomere II.

4.0 mm, IV = 3.0 rnm, and V = 4.0 rom.Exopodite of V flattened more than are theothers. U ropods uniramous, a pair of flattened,hook-ended, tubercular appendages, each 3.5mm long.

Male : No pigment, although some color isevident in the posterior digestive tract. Length6.0 mm, width 2.0 mm.

Head. Small in relation to body size. Tinyeyes. Antennae do not show from the dorsalaspect. Cephalon somewhat sunken into thora­comere I, but not fused to it.

Thorax. Seven segments, widely separatedlaterally . Seven pairs of strong pereopods. Mid­ventral swellings on I-VII, most pronounced onII-IV; very weak on I.

Abdomen. Six definite segments, sixth with aslight posterior indentation. Lamellae of I-Vdefinitely swollen ventrally, indicating unira­mous pleopods , but much more peripheral thanis usual for male bopyrids. Weak midventralswelling on pleomere I only.

REMARKS : The genus was first proposed byRichardson (1910, pp . 33-35) for Merocepon

(Eniwetok)

A female bopyrid .pilttm11tls sp.Station 355, Fred

Island.28 July 1967 .DATE :

xanthi found in Pbym odius tmgttlatltS from thePhilippine Islands . Shiino (1936a, pp. 164­167) found M erocepon xanthi in Japan, and ap­parently felt that the exopodites of pleopod I asdescribed by Richardson were not the pleopoda,but were the lateral plates of pleomere I. Shiinoalso mentioned midventral swellings on allthoracomeres and on pleomere I of the male hedescribed; Richardson made no mention of suchswellings on her male specimen.

The hosts of the Japanese forms were Actaeasp. Cblorodopsis pilumnoides, and X anthiaselegans. Subsequently, Me rocepon xanthi wasreported from Palau (Shiino, 1942, p. 444) onthe crab Pbymodius monticulosis. Thus Mero­cepon xanthi has been collected five times fromfive different host species, and the new M. kntt­dseni is from yet a different host genus andspecies.

The new form differs from M erocepon xanthiin many part iculars, one of the most obviousbeing that of size. The M. kntldseni female is18.0 mm long and the male, 6.0 mm, whereasthe M . xanthi female and male were 3.3 mmand 1.5 mm, respectively. Other differences areshown in Table 3.

Richardson (1910, p . 34) apparently used­as a critical separating feature from the closelyrelated genus Scyracepon-i-tue number of mid­dorsal "bosses" on M el'ocepon xanthi, the leaf­like exopodites of pleopod I ( the identificationof which Shiino felt was in error), and the seg­mentation of the male abdomen. Of these threecriteria, the fused pleon of Scyracepon malesalone is of value. Nevertheless, the genus M el'o­cepon apparently is valid.

The female holotype and the male allotypewere deposited in the Allan Hancock Founda­tion collection as nos. 6512 and 6512a, respec­tively.

Named in honor of Dr. J. W . Knudsen, whofound this interesting form at Eniwetok Atoll.

Scyracepon hawaiiensis RichardsonScyracepon hawaiiensis Richardson 1911, pp .

645-647Fig. 5

MATERIAL:

HO ST:

AREA:

B

nc

A

Epicarids of Eniwetok-DANFORTH 469

TABLE 3

COMPARISON OF Mel'ocepon xanthi WITH M . knudseni

FEATURE Mel'ocepon xanthi Me1'Ocepon knudseni

<;> head<;> thorax

<;> pleon

J headJ thoraxJ pleon

Bilobate only slightly, at the front.Weakly costate, segments II-IV with largepleural bosses only.

3 pairs of coxal plates, small, triangular, onsegments II-IV (Sh iino gives I-IV) .Exopod of pl eopod I "leaf-like" (probablyRichardson's error) .Eyes obvious .No mention of midventral swellings.Pleopods circular swellings in "normal" lo­cation.

Very strongly bilobed for entire length.Strongly costate, segments I-IV with bothpleural boss and large swollen posterolaterallobe.4 pairs of coxal plates, large, circular, onsegments I-IV.Exopods of all pleopods similar in appear­ance.Eyes minute.Midventral swellings on all thoracomeres.Pleopods I-III with tiny medial projections.All pleopods slightly peripheral to normallocation .

FIG. 5. Scyracepon hawaiiensis. a, Right part ofdorsal aspect of female, terminal 4 pleomeres re­moved ; b, profile of thorax , thoracomere VII indicatedby "X"; c, ventral aspect, left app endages of femalepleomere I.

the pleon have appendages on the left, whilethere are 5 on the right.

Male : No male was found with this adultfemale, which is unfortunate, since the partial ortotal fusion of the pleomeres of the Scyraceponmale is unique for this group of bopyrids.

cB

A

REMARKS : Tattersall (1905, p. 35) estab­lished the genus and species Scyracepon tuber­culosa from Ireland; S. hawaiiensis was de­scribed by Richardson (1911, p. 645) from theHawaiian Islands; S. oceanicum was found inPalau (Shiino, 1942, pp. 450-452) ; and Shiino(1936b, pp . 170-173) also named S. quadri­hamatum from Shimoda, Japan. Despite the factthat the original description gave the head ofthe female as "simple, elliptical," the heads ofS. hawaiiensis, S. oceanicum, and S. qttadrihama-

DESCRIPTION :

Female : Found in the right gill chamber ofthe host. Color white in preservative. Bodytwisted slightly to the left. No pigment spots.Length 4.5 mm, width 4.0 mm. (The length ofthe S. hawaiiensis female from Hawaii was 5.0mm, according to information from the Smith­sonian Institution-Richardson neglected to in­dicate any size.)

Head. Bilobed, with a wide velum forminga flat anterior surface to the cephalon. No eyes.

Thorax. Seven dearly defined thoracomeres,each with a middorsal area slightly thicker thanthe corresponding lateral parts; that of V con­siderably raised, that of VI high and projectedposteriad, and that of VII a definite spine.Thoracomeres I-IV with pronounced pleuralbosses that are folded anteriorly; more evidenton the right (long) side than on the left. Fourpairs of coxal plates on I-IV, approximatelyspherical. Segments V-VII without evidentpleural bosses or coxal plates, and completelycovered by the abdominal lamellae. Marsupiumvery deep, completely covered; oostegite pair Vquite tumid . Eggs, but no embryos, present.Seven pairs of well-formed pereopods.

Abdomen . Six segments, the telson havinguniramous uropods, fringed, and similar in ap­pearance to the pleonal lamellae. Pleomeres I­V with biramous pleopods; endopodites as smallswellings, exopodites being long, fringed, andalmost identical to their corresponding pleurallamellae. There is an individual deformity onthe specimen, inasmuch as only 4 segments of

470

turn are bilobed (the head of the last was some­what damaged).

There is some ambiguity regard ing the pleonappendages, since Tattersall stated that thepleopods were biramous throughout, and therami were coarsely pinnate on one edge. He didnot mention any pleonal lamellae. Richardsoncorrected this to indicate that the "biramous"structures were really the "lame pleurale" andthe pleopod exopodite of each segment, with theendopodite of the pleopod present only as asmall swelling. Shiino apparently agreed withthis approach, and the specimen in hand bearsit out.

The use of the number of middorsal spinesfor identification of cepons is questionable atbest and should be employed only after all otherfeatures have been explored. For instance, Tat­tersall (1905, p. 35) indicated that in S. tuber­culosa, thoracomeres II-VII had dorsal bosses. . 'WIth only 3 pronounced. RIchardson's sketch ofS. hawaiiensis (1911, p. 645) shows but 3major elevations; Shiino (1942, p. 450) gives"Dorso-median process present on 5th to 7thsegments ..." for S. oceanicum; Shiino (1936b,p. 171) stated that for S. qltadrihamatltm thethoracomeres IV-VII were provided with me­diodorsal processes. Thus these forms would beMesocepon of Shiino (1951, pp. 36-39) , Mero­cepon of Richardson (1910, pp. 33-34), andCancricepon of Giard and Bonnier (1887, p.172) , if the processes and their number werethe only criteria.

LITERATURE CITED

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CHOPRA, B. 1923. Bopyrid isopods parasitic onIndian decapod Macrura. Records of the In­dian Museum, vol. 25, pp . 411-550.

DANFORTH, C. 1963. First record of a Hawaiianshore bopyrid (Isopoda : Bopyridae) . Journalof Parasitology, vol. 49, pp. 847-850.

--- 1967. Northern Pacific Gigantione (Iso-

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poda) . Biological Bulletin, vol. 132, pp. 147­155.

DUVERNOY, G. 1840. Sur un nouveau genre deI'ordre des Crustaces Isopodes et sur I'especetype de ce genre : le Kepon typus. CompteRendu .. . de l'Academie des sciences, Paris,pp. 598-603.

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GIARD, A. 1906. Sur Ie Grapsicepon typttS Du­vernoy, parasite de Grapsas strigosus Herbst.Compte Rendu . . . de la Societe de biologie,Paris, vol. 61, pp. 704-706.

GIARD, A., and J. BONNIER. 1886. Sur le genreCepon. Compte Rendu .. . de l'Academie dessciences, Paris, vol. 103, pp. 889-892 .

--- 1887. Contributions al'etude des Bopy­riens. Travaux de l'Institut zoologique deLille et du Laboratoire de zoologie maritimede Wimereux, vol. 5, pp. 1-272.

HANSEN, H. 1897. Reports on the dredgingoperations off the west coast of CentralAmerica . . . by the U.S. Fish CommissionSteamer "Albatross" during 1891. XXII. TheIsopoda. Bulletin of the Museum of Compara­tive Zoology, Harvard, vol. 31, pp . 95-129.

MOUCHET, S. 1932. Sur la presence d'un Cepe­nien dans une Galathee. Bulletin de la Societezoologique de France, vol. 56, pp. 504-506.

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NOBILl, G. 1905. Decapodi e Isopodi della Nu­ova Guinea Tedesca, raccolti dal Sign. 1.Biro. Termeszettudomanyi Muzeum (Buda­pest), Annales historico-naturales Musei Na­tionalis Hungarici, vol. 3, pp . 480-507.

RICHARDSON, H. 1904. Contributions to thenatural history of the Isopoda. Second Part.V. Isopod crustaceans of the northwest coastof North America. Proceedings of the U.S.National Museum, vol. 27, pp. 657-681.

--- 1910. Marine isopods collected in thePhil ippines by the U.S. Fisheries Steamer"Albatross" in 1907-8. Department of Com­merce and Labor, Bureau of Fisheries Docu­ment 736, pp. 33-44.

Epicarids of Eniwetok-DANFORTH

--- 1911. Description of a new paraSiticisopod from the Hawaiian Islands. Proceed­ings of the U.S. National Museum, vol. 38,pp . 645-647 .

SARS, G. 1885. Report on the Schizopoda, pp.220-221. In : Challenger Report, Zoology,vol. 13. British Government, London.

SHIINO, S. 1936a. Bopyrids from Tanabe Bay,III. Memoirs of the College of Science, KyotoImperial University, ser. B, vol. 11, pp. 157­174.

--- 1936b. Bopyrids from Shimoda andother districts. Records of OceanographicWorks in Japan, vol. 8, pp. 161-176.

--- 1939. A bopyrid from Palao. PalaoTropical Biological Station, Studies, vol. 1,pp. 597-601.

--- 1942 . Bopyrids from the South Sea Is­lands with description of a hyperparasitic

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cryptoniscid. Palao Tropical Biological Sta­tion, Studies, vol. 2, pp. 437- 458.

--- 1951. Some bopyrid parasites found onthe decapod crustaceans from the watersalong Mie Prefecture. Report of the Facultyof Fisheries, Prefectural University of Mie,vol. 1, pp. 26-40.

STEBBING, T. 1910. Isopoda from the IndianOcean and the British East Africa. In: Re­ports of the Percy Sladen Trust Expeditionto the Indian Ocean in 1905. Transactions ofthe Linnean Society of London, ser. 2(Zoology), vol. 14, pp. 83-122.

TATTERSALL, W. 1905. Isopoda, pp . 35-37. In:Scientific investigations, 1904. II. The ma­rine fauna of the coast of Ireland. Part V.Fisheries Branch, Department of Agricul­ture and Technical Instruction, Ireland .

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