JOURNAL OF CRUSTACEAN BIOLOGY, 27(2): 370–379, 2007

A NEW GENUS AND SPECIES OF BOPYRID ISOPOD INFESTING THE CRAB

MUNIDOPSIS DEPRESSA (ANOMURA: GALATHEIDAE) FROM THE GULF OF CALIFORNIA,

WITH NOTES ON ITS ECOLOGY

Ramiro Roman-Contreras and Christopher B. Boyko

(RR-C, correspondence) Instituto de Ciencias del Mar y Limnologıa (ICML), Universidad Nacional Autonoma de Mexico (UNAM).

P.O. Box 70-305. Mexico, D. F. 04510 (ramiror@mar.icmyl.unam.mx);

(CBB) Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street,

New York 10024, U.S.A. (cboyko@amnh.org).

A B S T R A C T

A new genus and species Bathione magnafolia of bopyrid infesting the deep-water galatheid crab Munidopsis depressa is described on the

basis of material collected in the southern Gulf of California, in depths between 835 and 870 m and extreme hypoxic conditions (0.007 and

0.29 ml O2/L). Females and males of the new species were compared with females and males of 21 closely related pseudionine genera.

Infestation rates by these bopyrids of M. depressa were estimated from 1.2% to 2.5%. Pseudione humboldtensis Pardo, Guisado & Acuna,

1998, shares many characters with the new species and is transferred to the new genus.

INTRODUCTION

The distribution of bopyrids in the eastern Pacific has beenreviewed by Markham (1986, 1992) who included twogenera of Galatheidae: Munida Leach, 1820, MunidopsisWhiteaves, 1874, as hosts of bopyrid isopods, in addition toPleuroncodes planipes Stimpson, 1860, reported previouslyby Markham (1975) off Baja California. The first twogenera are widespread throughout the eastern tropicalPacific and lists of galatheid species have been presentedby Hendrickx and Harvey (1999), and Hendrickx (2000,2003) for this region. Bourdon (1972) pointed out thatgalatheids constitute a group particularly exposed to bopyridinfestation and that approximately 60 species of galatheidcrabs are known to host bopyrid isopods. Markham (1986)ranked Munidopsis as the third most common galatheidgenus to be infested by bopyrids with 13 known host speciesfrom middle latitudes in the Atlantic, Pacific and Indianoceans. Genera found as parasites on Munidopsis includePseudione Kossmann, 1881, Pleurocryptella Bonnier, 1900,Parapleurocyptella Bourdon, 1972, and GalathocryptaRoman-Contreras and Soto, 2002. Nevertheless, exceptingPleurocryptella wolfii Bourdon, 1972, collected in the Gulfof Panama infesting Munidopsis antonii (A. Milne-Edwards,1884), there are no other records of bopyrids parasitizingany species of Munidopsis in the eastern Pacific (seeMarkham, 1992).

MATERIAL AND METHODS

During a four-leg survey of the deep water invertebrate fauna of the SE Gulfof California aboard the R/V El Puma of the Universidad NacionalAutonoma de Mexico (UNAM) undertaken in August and December 2000as well as March and June 2001, a large series of specimens of Munidopsisdepressa Faxon, 1893, were collected with a bottom sledge. Ninespecimens were branchially infested by bopyrid isopods that were notassignable to any described bopyrid genus, and a new genus and speciesare proposed to include the specimens herein described. Length of isopodsis given as anterior margin to posterior of telson, while that of the hosts isgiven as carapace length (CL, inclusive of rostrum). Sex and size of host isnoted, except when the specimen is no longer available for study. Type

specimens are deposited Acronyms in the Reference Collection of theLaboratorio de Invertebrados Bentonicos housed in Unidad Mazatlan,Universidad Nacional Autonoma de Mexico (UNAM) (EMU) and the LosAngeles County Museum (LACM).

SYSTEMATICS

Bopyridae Rafinesque-Schmaltz, 1815Pseudioninae R. Codreanu, 1967

Bathione gen. nov.

Diagnosis.—Head of female medially fused with first pere-iomere, all other segments separated; barbula formed by twopairs of different structures, inner pair tubular, surface finelysetose; outer pair enlarged, sub-flattened, fleshy, directedmedially; maxillipedal palp unsegmented; eyes and pig-mentation absent. Coxal plates of pereiomeres 5-7 lamellar,well developed, borders rounded; pleopods biramous,foliaceous, well developed; five pairs of uniramous lateralplates foliaceous, semi-ovoid, very well developed; marginsof pleopods and lateral plates slightly undulated, surfacessmooth; uropods uniramous. Head of male medially fusedwith first pereiomere; body shape linear (not tapering mark-edly anteriorly or posteriorly), pleopods globose, slightlyflattened; pleotelson trilobed; maxillipeds, midventral tuber-cles, pigmentation, eyes and uropods absent.

Type Species.—Bathione magnafolia n. sp.

Etymology.—Bathy- from the Greek genitive bathos, inreference to the depth of collection, combined with Ione; thegenus is feminine.

Hosts.—Galatheidae: Munidopsis depressa, Cervimunidajohni Porter,1903, and Pleuroncodes monodon (H. MilneEdwards, 1837).

Bathione magnafolia, new speciesFigs. 1-3

Material Examined.—Holotype female 6 mm, allotype male2.4 mm (EMU-5460), from left branchial chamber of female

370

Fig. 1. Female of Bathione magnafolia n. gen., n. sp., holotype (EMU-5460). A, dorsal view; B, same, ventral view (legs omitted); C, maxilliped and firststructure of barbula; D, palp of maxilliped. Scale bars: A & B ¼ 1.4 mm, C¼ 0.5 mm, D ¼ 0.062 mm.

371ROMAN-CONTRERAS AND BOYKO: NEW BOPYRID INFESTING GALATHEIDS

Fig. 2. Female of Bathione magnafolia n. gen., n. sp., holotype (EMU-5460). A, head with antennae and buccal cone, frontal view; B, left second structureof barbula; C, first right oostegite, dorsal view; D, same, ventral view; E, left first pereiopod; F, left seventh pereiopod. Scale bars: A, E & F¼ 0.25 mm;B, C & D ¼ 0.5 mm.

372 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 27, NO. 2, 2007

Fig. 3. Male of Bathione magnafolia n. gen., n. sp., allotype (EMU-5460). A, dorsal view; B, head with antennae, frontal view; C, left first pereiopod;D, left seventh pereiopod; E, pleon, ventral view; F, pleotelson, ventral view. Scale bars: A, C & D¼ 0.62 mm; B & E¼ 0.5 mm; F¼ 0.25 mm.

373ROMAN-CONTRERAS AND BOYKO: NEW BOPYRID INFESTING GALATHEIDS

Munidopsis depressa (17.4 mm CL) (EMU-5421A). Para-types: female (7 mm) and larva (EMU-5461) from leftbranchial chamber of female M. depressa (15.4 mm CL)(EMU-5421B); female (5.5 mm) and male (2.8 mm) (EMU-7030) from left chamber of M. depressa (13.1 mm CL)(EMU-6013); female (5 mm) and male (2.8 mm) (EMU-7031) from left chamber of M. depressa (14.2 mm CL);female (4.1 mm) and male (2.2 mm) (LACM CR 2000-067.1) from M. depressa; female (6 mm) (LACM CR 2000-067.2); single female (7 mm) (in Coll. R-C), from M.depressa; All type specimens collected by TALUD IV, St.25 (24853.29N, 108859.49W), 835-870 m, benthic sledge, 26Aug 2000. Nontypes: female (6 mm), male (2 mm) andlarva (in Coll. R-C), from left branchial chamber of femaleM. depressa (17.6 mm CL) (EMU-5422A); ovigerousfemale (6.5 mm) and male (2.3 mm) (in Coll. R-C) fromleft branchial chamber of female M. depressa (17.9 mm CL)(EMU-5422B); all nontypes collected by Talud V, St. 11(23814.09N, 107800.09W), 850-870 m, benthic sledge, 17Dec 2000.

Description.—Holotype female outline ovoid, body marginsslightly curved (Fig. 1A, B); total length 6 mm, maximalwidth at fifth pereiomere, 4.0 mm; head medially fused withfirst pereiomere, surface smooth, front rounded; frontallamella broad, eyes and pigmentation absent; anterolateralcorners of head produced into small rounded lobes.Maxilliped subquadrate, posterolateral portion slightlycurved (Fig. 1C); palp subovoid, unsegmented, nine setaeon distal and mesial margins (Fig. 1D), spur short andbroadly rounded. Antennula 3-segmented; basal segmentglobose; second segment subcylindrical; third segment sub-triangular, smaller, a tuft of short setae on tip. Antenna4-segmented; basal segment subpyramidal, incompletelyfused with third segment; segments 2-3 subcylindrical, distalsegment smaller than former, a tuft of small setae at tip (Fig.2A); barbula formed by two pairs of structures: inner paircylindrical, surface finely squamous (Fig. 1C); outer pairfleshy, subflattened, directed inward; middle region irregu-larly digitate (Fig. 2B). Pereiomeres dorsally, ventrally andlaterally distinct; coxal plates on pereiomeres 1-4 obscure,small gaps dividing borders in 2 rounded lobes on shortside, but only on first pereiomere on longer side; dor-solateral bosses absent; coxal plates 5-7 larger than previoussegments, lamellar, extending laterally, wider and largerposteriorly (Fig. 1A). Oostegites fully enclosing broodpouch; first oostegite 2-segmented, relatively small, cover-ing head and forming the anterior part of brood pouch,external surface smooth; anterior segment rounded, almost 3times as high as the distal segment, which is almost as wideas high, with posteriorly directed thin lobe (Fig. 2C); innersurface concave in both segments; subdigitate, smoothtransverse ridge dividing anterior and posterior segments(Fig. 2D); oostegites 2-5 different in shape, increasing insize posteriorly; fifth oostegite extending across posteriorborder of marsupium and overlapping opposite one.Pereiopods progressively larger posteriorly; first pereiopodrelatively small, uncarinated; surface of basis and ischiumsmooth; merus short; carpus and propodus fused, globose;surfaces of merus, and carpus-propodus slightly squamous(Fig. 2E), pereiopod 7 largest, elevated subpyramidal

squamous carinae proximally and distally on ventral surfaceof ischium; merus and carpus fused, small scales on ventralsurface (Fig. 2F). Pleon 1.6 times length of head/pereion; 5pleomeres dorsally and laterally separated, sixth segmentsubquadrate, small; lateral plates strongly developed,foliaceous; five pairs of biramous foliate pleopods, endo-pods and exopods very strongly developed, larger thanlateral plates (Fig. 1A, B); margins of both lateral plates andpleopods undulated, uropods uniramous.

Allotype Male.—Body unpigmented, elongated, clearlysegmented dorsally, ventrally and laterally; head ovoid,medially fused with first pereiomere; almost three times aswide as long; anterolateral borders rounded and producedventrally (Fig. 3B); maxillipeds and eyes absent; antennaedifferent in size, both 3-segmented; antennule with proximalsegment subspherical; second and third segments smaller;a small tuft of setae at tip of distal segment. Antenna withbasal segment subpyramidal; middle segment subcylindri-cal, slightly smaller than basal segment; distal segmentshortest, a small tuft of setae at tip (Fig. 3B). Pereiomereswidely separated, directed laterally (Fig. 3A), maximalwidth at seventh pereiomere; midventral tubercles absent;thin, uncarinated isomorphic pereiopods, slightly largerposteriorly; ishium slightly larger than carpus, carpusshortest (Fig. 3C, D). Pleomeres progressively narrowerposteriorly, distinctly separated, tips subrounded; flat,globose pleopods on pleomeres 1-5 near midline (Fig.3E); pleotelson produced in 2 rounded lateral lobes and onesmaller centrally, 3 small setae on distal lateral borders andone inner smaller seta posterolaterally; anal cone present;uropods absent (Fig. 3F).

Etymology.—From the Latin magna, great, and folia, leaf(magnafolia), in reference to the remarkable development ofpleopods and lateral plates of females. The gender isfeminine.

Type Locality.—Gulf of California (24853.29N,108859.49W).

Distribution and Ecology.—The host of Bathione magna-folia gen. et sp. nov., M. depressa, is currently known fromsouthern California, USA, to the Gulf of California (Baba,2005). In addition, there is one record from Baja California,Mexico (south of Isla San Pedro, ca. 278409N, 111822.69W,931-952 m), in the SCRIPPS crustacean catalogue (Luke,1977). The total known depth range is from 185 m to 1260-1300 m. Records in the Gulf of California are from26806.59N-110806.79W to off Tres Marias Islands (Hen-drickx, 2003). Review of selected samples of M. depressa inthe holdings of the Los Angeles County Museum of NaturalHistory showed no presence of any bopyrid parasites.

During this study a total of 707 specimens of M. depressawere collected in 11 sampling stations and examined forbopyrids. Only nine specimens (1.2%) were infested; thesewere all collected within a depth range of 835-870 m.Within each individual sample that contained bopyridspercentages of infestation were from 1.2% to 2.5%. In thesouthern Gulf of California, where the samples of P.magnafolia were collected, epibenthic dissolved oxygen isconsidered the most important environmental parameter on

374 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 27, NO. 2, 2007

the outer continental shelf and upper slope. Severe hypoxicor anoxic conditions occur from ca. 150 m to ca. 750 m,rendering this depth range inhospitable for survival ofmacrofauna. Below that depth, a moderately rich decapodcrustacean fauna distinct from the fauna found on theplatform is found. M. depressa is one of the dominantspecies of this community and it is able to withstand dis-solved oxygen concentrations as low as 0.07-0.76 ml O2/L(Hendrickx, 2001, 2003; present work, table 1). Specimensinfested with B. magnafolia were obtained in extremelyhypoxic conditions (0.07 and 0.29 ml O2/L) and were asso-ciated with the two largest concentrations of M. depressa(163 and 273 specimens) detected during this survey(Table 1).

DISCUSSION

Twenty-five bopyrid genera were grouped by Shiino (1965)into a ‘‘Pseudione-group’’, which was later formalized byCodreanu (1967) as a subfamily. The majority of the species(currently 54) are placed into the heterogeneous genusPseudione. Over the past 30þ years many new genera havebeen erected to contain new species of pseudionines, as wellas include older species formerly placed in the genusPseudione (see Bourdon, 1976).

Bathione magnafolia presents the following importantcharacters for comparison with other galatheid-infestingpseudionines: 1) female with fusion of the head with pere-iomere 1 and with 6 pleonal segments, 5 pairs of biramouspleopods, uniramous lateral plates, and uniramous uropod-like extension of the pleotelson, 2) unsegmented palp on themaxilliped and barbula composed of 2 unlike pairs ofappendages, 3) female coxal plates lamellar and (at least inpart) well developed, 4) male head medially fused with firstpereiomere, 6 pleonal segments, 5 pairs of uniramouspleopods and no uropods.

In the present work, important generic characters of bothfemales and males for Bathione were compared with 21genera in the subfamily Pseudioninae, that contain speciesfound infesting galatheoid anomurans (Table 2) and appearto be the most basal of peudionines (Shiino, 1965; personalobservation). Although bopyrid genera are usually separatedbased on the characteristics of the females, we have includedseveral male characters as well and feel strongly that males,despite their often plesiomorphic features, deserve moreattention when considering generic affiliations. A compar-

ison with all pseudionines is not given here, as the closestrelatives of Bathione are all found infesting galatheoids(personal observation). Although a thorough revision of thePseudioninae is desirable, such a feat is outside the scope ofthis work.

One of the most conspicuous characters of both femalesand males of B. magnafolia is the partial fusion of the headwith the first pereiomere. This character does not appear tobe frequent among Pseudioninae taxa and, except for B.magnafolia, no species in any of the compared generaexhibit this character. However, the fusion of the head andthe first thoracic segment is frequently observed in femalesof the subfamily Bopyrinae (Shiino, 1965; Bourdon, 1968),so that at the generic level Bathione appears to share thefusion of the head more with bopyrine genera than withother members of the subfamily Pseudioninae. The fusion ofthe head with the first pereiomere of males was noted byBonnier (1900) for the genus Bopyrella Bonnier, 1900, andhe considered fusion of the head and the first pereiomere tobe an important diagnostic features for the males. Shiino(1949) and Adkison and Heard (1978) also considered theimportance of the fusion of head and the first pereiomere tobe important in the systematics of bopyrids, but Boyko andWilliams (2001) suggested that the reliability of the fusionof the head and the first pereiomere is not a diagnosticfeature because of the potential for variability of this char-acter among the individuals in a same species when largerseries of specimens are examined. Given that cryptoniscidsmay become either males or females depending on whetheranother individual is present on the host (Trilles, 1999), thefusion of the head and pereion should be studied carefullyin both males and females to determine if it is a usefuldiagnostic character for either or both sexes.

In Shiino’s (1965) opinion, the gradual degeneration ofthe organs increases as evolution progresses in bopyridlineages, and the fusion of pleomeres and progressive loss ofpleopods in both males and females are the best-documentedexamples of this. Shiino (1965) stated that the fusion ofpleomeres constitutes a typical feature in the evolution ofbopyrids. Sars (1898) noted that in males of the familyBopyridae the ‘‘metasoma sometimes is distinct’’, i.e., sepa-rate segments, but in other times it is ‘‘confluent’’, i.e.,fusion of some or all segments. Among the pseudioninesthis feature is likewise not common in females being seenamong four of the compared genera. However, fusion of

Table 1. Specimens of Munidopsis depressa infested with Bathione magnafolia n. g., n. sp. collected in the SE Gulf of California. T ¼ TALUD cruise;M ¼Males; F¼ Females; OF ¼ Ovigerous females.

Cruise StationDate of

collectionDissolved

oxygen (ml/L) Depth (m)

Specimens collectedSpecimens

with parasiteM F OF

T IV 25 26-Aug-00 0.29 835-870 207 64 4 7T IV 26 26-Aug-00 0.76 1225-1240 33 13 3 NONET IV 33 27-Aug-00 0.51 1040 1 0 1 NONET V 11 17-Dec-00 0.07 850-870 119 11 33 2T V 18 15-Dec-00 0.15 940-990 9 0 0 NONET VI 18 15-Mar-00 0.29 890-950 6 1 8 NONET VI 25 16-Mar-00 0.20 830-850 3 0 1 NONET VII 18 7-Jun-00 — 950-1010 37 2 29 NONET VII 25 8-Jun-00 0.10 780-850 5 0 0 NONET VII 32B 9-Jun-00 0.10 850-880 72 0 44 NONET VII 33B 9-Jun-01 0.60 1260-1300 1 — — NONE

375ROMAN-CONTRERAS AND BOYKO: NEW BOPYRID INFESTING GALATHEIDS

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376 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 27, NO. 2, 2007

pleomeres is about as common as not, with males of 12genera showing fusion. There seems to be separateevolutionary tracks for female and male pleomere fusionas only females and males of Balanopleon Markham, 1973,Kolurione, and Orbimorphus Richardson, 1910a, bothshow fusion. The possession of six distinct pleomeres inboth female and male Bathione magnafolia is shared withseven of the compared genera (and partly with Pleuro-crypta, in which the males are highly variable in degree ofpleomere fusion).

The palp of the maxilliped in female bopyrids can beeither unsegmented (rarely 2 segmented as in Parapleur-ocryptella) or absent. Bourdon (1972) considered thebisegmentation of the palp in females of bopyrids as anarchaic character and is does indeed appear as if the morederived pseudionines show the most reduced palps andmaxillipeds of females with segmented palps are lesscommon than those with unsegmented palps. The un-segmented palp of Bathione is shared with the galatheoid-infesting pseudionine genera Allorbimorphus Bourdon,1976, (in part), Aporobopyrus Nobili, 1906, Galathocrypta,Kolourione Markham, 1978, Parione Richardson, 1910,Parioninella Nierstrasz and Brender a Brandis, 1930,Pseudione (in part), and Pleurocrypta Hesse, 1865 (seeTable 2), but in all other characters they differ markedlyfrom those genera.

The barbula is a term proposed by Markham (1988) forthe projections on the posterior margin of the female headand has been a character extensively illustrated by Bonnier(1900) but not used in his description of bopyrid species.The barbula as composed by two pairs of lamellae is thestate most frequently observed among the pseudionines(Table 2); an exception to this rule is Aporobopyrus inwhich the barbula is formed by two pairs of digitate struc-tures. The barbula composed of only one lamellar pair ispresent in 4 galatheoid-infesting genera (Table 2) whereasin the genus Pleurocryptella the barbula may be either ofone or two (or even including a third small structure insome species of the genus Probopyrus Giard & Bonnier,1888 (R. Bourdon, personal communication to R-C, 1999)depending on the species. In Parione the barbula iscomposed of two structures, but the outer lamellar pair ismuch larger than the inner pair. In Bathione, the barbula is,as in the majority of the other compared genera, composedof two pairs of structures. However, the inner pair is tubularand the outer pair is fleshy and this kind of barbula has notbeen previously observed in other galatheoid infestingpseudionines.

Adult isopods usually have five pairs of pleopods but inmany bopyrids species both sexes may have a reducednumber, or abdominal limbs may be lacking completely(Calman, 1909; Schultz, 1969; McLaughlin, 1980). Thisreduction appears to always be correlated with a reductionin the number of pleomeres for females, but not in all casesfor males. Females of Bathione show the primitive state forboth the number of pleomeres (6) and pleopods (5 pairsbiramous). In these, they agree with females of 15 othergalatheid-infesting genera, including Pseudione (putativelythe most primitive genus in the subfamily). However, thepleopods in Bathione differ markedly from those of otherT

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377ROMAN-CONTRERAS AND BOYKO: NEW BOPYRID INFESTING GALATHEIDS

compared genera due to their exceptional development thatoverreaches the borders of the lateral plates. Pleopods arepresent on males of 11 genera of galatheoid-infesting pseud-ionines, with nine genera containing species bearing 5 pairsof uniramous pleopods and two genera (Allorbimorphusand Parione) containing species with only 4 pairs.

The presence of the uropods is variable in the bopyridfemales but when present, the uropods can be composed ofone or two rami. Uniramous uropods are more frequentlyobserved than the biramous type (Table 2). Sometimesthe presence of uropods is variable within a single genus(Anuropodione Bourdon, 1967). In the genus Galathocrypta,the presence of uropods in the female is unclear, as thisdepends on the definition of the uropod itself. Generally,a uropod is often considered to be any structure protrudingfrom the pleotelson of the sixth pleomere, but some authors(Adkison and Heard, 1978) consider uropods to be onlythose structures that are set off from the pleomere bysutures, as in species of Ione Latreille, 1817. Females ofBathione share their uniramous uropods with the majority ofthe compared genera (Table 2). Male uropods are much rarerand are seen in only three of the compared genera (Table 2);they are lacking in Bathione.

Shiino (1965) also considered the evolution in bopyridfemales of the elongation of the lateral plates. Thesestructures are absent in Astalione Markham, 1975, andvariously developed in the other compared genera (Table 2).The best developed lateral plates were previously seen inspecies of the genus Munidion, but those of Bathione areeven larger and of a shape seen in none of the othergalatheoid-infesting genera.

Bathione is similar to females and males of species ofAporobopyrus and Galathocrypta, as well as some speciesof Pseudione (probably a paraphyletic genus and thereforedifficult to discuss in terms of generic characters). Femalesof species in these genera have 6 pleomeres, moderately towell-developed lateral plates, and 5 pairs of biramouspleopods. All species of Aporobopyrus, Galathocrypta, andBathione have unsegmented maxilliped palps, whereasPseudione species either have this state or lack palpsentirely. Males of all 4 genera have 6 pleomeres and lackuropods, and most have 5 pairs of pleopods (somePseudione species lack pleopods). Bathione females differfrom those of Aporobopyrus in having better-developedcoxal plates and unequal, non-digitate barbular lobes; themales are similar to those of Aporobopyrus but have a morepronounced trilobation of the pleotelson. They differ fromfemales of Galathocrypta in having 2 pairs of barbular lobes(1 pair in Galathocrypta), and in lacking the uropod-likeextensions of the pleotelson; the males possess 5 pairs ofpleopods lacking in Galathocrypta. Bathione females differfrom those of Pseudione in having two very differentbarbular lobes and a strongly digitate posterior barbularmargin (two similar pairs of lobes and a smooth posteriormargin in Pseudione); the males are similar to those ofPseudione males (especially those from species infestinganomurans). Females of Bathione differ from those of allthree other genera in having extremely developed lateralplates on the pleomeres that completely obscure thepleopods in dorsal view. Although Bathione magnafolia is

clearly related to Aporobopyrus and Pseudione (at least inpart), the above-cited differences justify the erection a newgenus and species for this parasite.

Specimens of Pseudione humboldtensis Pardo, Guisado &Acuna, 1998 (found on hosts Cervimunida johni andPleuroncodes monodon) are very similar to those ofBathione magnafolia in all important characters and thisspecies is transferred herein to Bathione. Females of the twospecies differ in degree of head and first pereiomere fusion(fused in B. magnafolia vs. distinct in B. humboldtensis),proportionally larger lateral plates and pleopods in B.humboldtensis, more pronounced digitation on the innermargin of the first oostegite in B. humboldtensis, and inhaving differently shaped outer barbular lobes. Males of thetwo species are very similar and difficult to separate, basedon published illustrations and description of B. humbold-tensis, except for the fusion of head and first pereiomere inB. magnafolia, which is not found in B. humboldtensis.Males of Bathione humboldtensis are said to lack pleopodsbut the illustration provided gives the suggestion of low,rounded pleopods such as seen in males of B. magnafolia.When describing Pseudione humboldtensis, Pardo et al.(1998) compared this species to Pseudione brattstroemiStuardo, Vega and Cespedes, 1986, a parasite of the call-ianassid Neotrypaea uncinata (H. Milne Edwards, 1837).Females of P. brattstroemi are very different from eitherBathione species in having crenulated coxal plates (notcrenulated in Bathione spp.), tuberculate outer barbularlobes that are much shorter than those seen in Bathione spp.,and pereiopods strongly tuberculated on entire surface(weakly marginally tuberculate in Bathione spp.). Males ofP. brattstroemi differ from those of Bathione spp. in havingmarkedly laterally elongated pleomeres differing little intheir relative width (posterior pleomeres much narrowerthan anterior ones in Bathione spp.), clearly lacking anypleopods (low rounded pleopods likely in both Bathionespp.), and having a laterally elongate pleotelson with littleto no median projection (narrow, rounded and trilobed inBathione spp.). Clearly, P. brattstroemi is genericallydistinct from both species of Bathione and is retained inPseudione in the absence of a thorough revision of thatgenus. The most obvious similarity between females of P.brattstroemi and those of Bathione spp. is in the extremelyenlarged lateral plates and pleopods. However, this char-acter must be treated with caution as it is very possible thatdevelopment of these structures, being respiratory in func-tion, may sometimes reflect independent origins in regionsof low oxygen content (see Pardo et al., 1998), rather thannecessarily shared common ancestry. An additional speciesthat has been discussed in terms of its possible relationshipsto Bathione humboldtensis is Pseudione tuberculataRichardson, 1904, but this species can easily be distin-guished from both species of Bathione by both female(proportionally smaller head, deeply inserted articulatedmaxilliped palp, margins of pereiopod segments weaklyundulating in P. tuberculata vs. larger head partially fusedwith first pereiomere, non-inserted, non-articulated maxilli-ped palp, strongly crenulated margins of pereiopods inBathione spp.) and male (head and first pereiomere separate,anteriorly and posteriorly tapered body form, rounded

378 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 27, NO. 2, 2007

pleotelson in P. tuberculata vs. head and first periomerefused, linear body form, trilobed pleotelson in Bathionespp.) characters. Previous confusion regarding these spe-cies’ relationships indicated the need for a comparison ofall important morphological features to properly assessrelationships in bopyrids, especially among the complexpseudionines.

ACKNOWLEDGEMENTS

This project was partly supported by CONACyT (contract 31805-N). Theauthors express special thanks to Dr. M. Hendrickx (Unidad Mazatlan,ICML, UNAM) for the loan of specimens, ecological notes andsuggestions to improve the present work. Thanks are given also to M.Sc. M. Martınez-Mayen (ICML, UNAM) for his help in laboratory. Shiptime was granted by the Consejo Tecnico de la Investigacion Cientıfica(CTIC), UNAM. Gary C. B. Poore (Museum Victoria, Australia) and twoanonymous reviewers offered many helpful suggestions that improved themanuscript.

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RECEIVED: 14 February 2006.ACCEPTED: 4 August 2006.

379ROMAN-CONTRERAS AND BOYKO: NEW BOPYRID INFESTING GALATHEIDS