The asterocherid siphonostomatoid copepod
Asterocheres hirsutus, a new species, is described from a
hexactinellid sponge of the genus Rossella Carter collected during the Polastern cruise ANT XVII/3, off
South Shetland Islands. The distinctive features of this
new species are: a female with 21-segmented and a male
with 17-segmented antennules, praecoxal endite of
maxillule more than four times longer than palp and the
ornamentation of the posterior surface of legs 1–4. A
detailed description of both sexes is presented

Bandera García, María Eugenia

Conradi Barrena, Mercedes

López González, Pablo José

English

idUS. Depósito de Investigación Universidad de Sevilla

ORIGINAL ARTICLEMª Eugenia Bandera Æ Mercedes ConradiPablo J. Lo´pez-Gonza´lezAsterocheres hirsutus, a new species of parasitic copepod(Siphonostomatoida: Asterocheridae) associated with an Antarctichexactinellid spongeReceived: 11 August 2004 / Revised: 19 June 2005 / Accepted: 4 July 2005 / Published online: 6 September 2005 Springer-Verlag and AWI 2005Abstract The asterocherid siphonostomatoid copepodAsterocheres hirsutus, a new species, is described from ahexactinellid sponge of the genus Rossella Carter col-lected during the Polastern cruise ANT XVII/3, oﬀSouth Shetland Islands. The distinctive features of thisnew species are: a female with 21-segmented and a malewith 17-segmented antennules, praecoxal endite ofmaxillule more than four times longer than palp and theornamentation of the posterior surface of legs 1–4. Adetailed description of both sexes is presented.Keywords Asterocherid siphonostomatoid ÆHexactinellid sponge Æ Symbiosis Æ AntarcticaIntroductionThe Asterocheridae Giesbrecht, 1899 is the largest familyof the siphonostomatoid copepods with about 200 spe-cies. This family exploits the potential diversity that existsamong invertebrate organisms as hosts and can be foundassociated with molluscs, bryozoans, corals, echino-derms, polychaetes, sponges and ascidians (Ivanenko andSmurov 1997; Johnsson and Bustamante 1997).Among copepods of the family Asterocheridae, thetype-genus Asterocheres Boeck, 1859 is the most speciosewith about 33% of the known species, 56% of whichhave been found associated with sponges. Despite thefact that the sponges are one of the groups that domi-nate many of the Antarctic shelf benthic communities(Gale´ron et al. 1992), only one species of Asterocheresassociated with sponges is known in this area.Research on the biodiversity in the Southern Oceanhas increased greatly in recent decades (Arntz 1997).Nevertheless, the research eﬀort directed at the diﬀerenttaxonomic groups has not been uniform. Some surveyshave been carried out within the framework of interna-tional programs, such as EASIZ (Ecology of the Ant-arctic Sea Ice Zone), in order to improve theunderstanding of certain, as yet poorly known, groups inthe Southern Ocean. These expeditions gave the authorsthe opportunity to study some fauna associated toAntarctic invertebrates. In the present work we describea new species of Asterocheres found associated with ahexactinellid sponge of the genus Rossella Carter.MethodsSponges infected with parasitic copepods were collectedon the R/V Polarstern cruise ANT XVII/3 (EASIZ III)sponsored by the Alfred Wegener Institut fu¨r Polar- undMeeresforschung, Bremerhaven, during the australsummer of 2000. The material was collected with the aidof Agassiz trawl, sorted, labelled and ﬁxed on board.Symbiotic fauna was obtained by pouring the washwater through a 100 lm mesh net. The copepods wereﬁnally recovered from the sediment retained and pre-served in 70% ethanol.Selected specimens were stained with Chlorazoleblack E (Sigma C-1144), dissected in lactic acid andexamined as temporary mounts in lactophenol. All ﬁg-ures were drawn with the aid of a camera lucida on aLeica DMLB diﬀerential interference microscope. Inorder to detect minute details, some specimens wereprepared and photographed using a PHILIPS XL30SEM. All appendage segments and setation elements arenamed and numbered using the system established byHuys and Boxshall (1991).Material examined in the present paper is depos-ited in the Zoologisches Institut und ZoologischesCommunicated by R.M. KristensenMª E. Bandera Æ M. Conradi Æ P. J. Lo´pez-Gonza´lezBiodiversidad y Ecologı´a de Invertebrados Marinos,Departamento de Fisiologı´a y Zoologı´a, Facultad de Biologı´a,Universidad de Sevilla, Reina Mercedes 6,41012 Sevilla, SpainE-mail: ebandera@us.esHelgol Mar Res (2005) 59: 315–322DOI 10.1007/s10152-005-0007-2Museum in Hamburg (ZMH) and in the collection ofBiodiversidad y Ecologı´a de Invertebrados Marinosresearch group of the University of Seville (BEIM).ResultsAsterocheres hirsutus sp. nov (Figs. 1, 2, 3, 4, 5)Material examinedSixty-three females and nine males associated with thehexactinellid sponge Rossella sp. collected from thePolarstern cruise ANT-XVII/3 (EASIZ-III), oﬀ SouthShetland (Antarctica), stn. 178.2, 6158.50’S 6019.70’W,804–930 m depth, 2 May 2000. The holotype, 1 adultfemale (K 40872), allotype, 1 adult male (K 40873),paratypes, 20 females and 4 males (K 40874) have beendeposited in the ZMH. The rest of the material isdeposited in the collection of BEIM (COP-504).Adult femaleBody cyclopiform (Figs. 1, 2), slender with cephalotho-rax oval and cyclindrical urosome (Figs. 1a, b.). MeanFig. 1 Asterocheres hirsutus sp.nov. Female, a, habitus, dorsal;b, habitus, lateral; c, urosome,ventral; d, ﬁfth leg, dorsal; e,second antenna316body length 820 lm; with range of 759–875 lm (basedon three specimens). Ratio of length to width of pro-some 1.44: 1. Ratio of length of prosome to that ofurosome, 2:1. Prosome comprising the cephalothoraxfully incorporating ﬁrst pedigerous somite and three freepedigerous somites. Somite bearing leg 4 is much smallerand narrower than preceding ones.Urosome 4-segmented comprising leg 5-bearing so-mite, genital double-somite and two free abdominalsomites. Somite bearing leg 5 (Fig. 1c) wider than long,40·80 lm with some spinules on dorsal surface. Genitaldouble-somite as long as wide, bearing genital apertures,paired gonopores located laterally. Lateral margin ofdouble-somite ornamented with fringe of long spinuleslocated about midway along double-somite, posterior togonopores level (Fig. 1a, b, c; 4 e, g). Each genital areaarmed with one plumose seta and one spiniform ele-ment. Two postgenital somites subquadrate (Fig. 1c).Dorsal surface of free abdominal somites and posteriorpart of double-somite ornamented with tiny spinules.Caudal rami 2.5 times longer than wide (Figs. 1c, 4e),armed with six setae. Two medial dorsal naked setae,outer 100 lm long and inner 96 lm. Four terminal setae:outermost terminal setae, 90 lm; innermost, 94 lm, bothFig. 2 Asterocheres hirsutus sp.nov. Female, a, antennule; b,detail of the compound segment9 (IX–XII) of the antennule; c,oral cone; d, mandible; e, tip ofmandibular stylet; f, maxillule;g, maxilla; h, maxilliped317with setules on inner side; and two median terminalplumose setae, 210 lm (outer) and 300 lm (inner).Surface of caudal ramus ornamented with minute spin-ules.Antennule 369 lm long and consist of 21 articulatingsegments (Fig. 2a). Segmental fusion pattern asollows: 1(I), 2(II), 3(III), 4(IV), 5(V), 6(VI), 7(VII),8(VIII), 9(IX–XII), 10(XIII), 11(XIV), 12(XV),13(XVI), 14(XVII), 15(XVIII), 16(XIX), 17(XX),18(XXI), 19(XXII–XXIII), 20(XXIV–XXV), 21(XXVI–XXVIII). Lengths (lm) of its segments are as follows(measured along their posterior margin), 21 (30 alonganterior margin), 14, 12, 10, 14, 10, 12, 14, 12, 7, 10,21.8, 23.6, 18.7, 23.4, 23.4, 23.4, 26.5, 29.6, 15.6, 17, 10.Segments 1–8 each with 2 setae; segment 9 with 8 setae;segment 10–17 each with 2 setae; segment 18 with 2 setaeplus an aesthetasc; segment 19 with 2 setae; segment 20with 3 setae; segment 21 with 7 setae. Segment 10 (XIII)reduced, partly overlapped by distal expansion of com-pound segment 9 (IX-XII) (Fig. 2b).Antenna biramous and 180 lm long excluding ter-minal claw (Fig. 1e). Small unarmed coxa with tuft ofspinules. Elongated unarmed basis ornamented with ﬁnespinule row and bearing 1-segmented exopodite andFig. 3 Asterocheres hirsutus sp.nov. Female, a, leg 1; b, leg 2;c, leg 3; d, leg 4318long 3-segmented endopodite. Exopod small, longerthan wide armed with one lateral and two unequal apicalsetae, the longer three times longer than the small one.First segment of endopodite elongate, 61·26.5 lm, un-armed but ornamented with rows of spinules; secondsegment produced distally on medial side but articulat-ing with third segment proximally on lateral side andarmed with one plumose short seta and two setules atbase. Third segment armed with two plumose setae andlarge distal claw, 93 lm long, and also ornamented withrows of ﬁne spinules shortened in length.Mandible with 2-segmented palp and stylet-likegnathobase (Fig. 2D). Stylet 192 lm long, with subapi-cal denticulate margin (Fig. 2e). First segment of palpslender, unarmed but ornamented with a row of spinuleslaterally; second segment half length of ﬁrst one, with 2terminal unequal plumose setae. Stylet located in oralcone. Oral cone (Fig. 2c, 4a,b) formed by labrum andlabium joined laterally, 195 lm long, reaching intercoxalsclerite of leg 1. Cone broad proximally and taperingdistally. Labrum almost completely covers labium. Tipof labrum curved posteriorly, with ribbed surface anddense hair-like ornamentation.Maxillule bilobed (Figs. 2f, 4b); praecoxal enditemore than four times longer than palp, armed with ﬁvedistal setae, four plumose and one naked and shorter,and ornamented with a row of spinules laterally. Palparmed with three terminal and one subterminal setae, allplumose.Maxilla 3-segmented (Figs. 2g, 4d). Praecoxa bearinglong ﬂaccid element medially, possibly an aesthetasc;coxa unarmed and claw-like basis bearing small hyalineprocess proximally in axil. Claw surface with minutespinules arranged irregularly in medial part, armed with1 very small seta at about one half length laterally andwith rows of minute spinules distally.Maxilliped 5-segmented (Fig. 2h). First segment withsmall inner distal seta and patch of ﬁne spinules. Secondsegment elongate and slender with spinules distally andlaterally. Third segment short, with three setae, two ofthem naked. Fourth segment armed with one plumoseseta. Fifth segment ornamented with patches of smallspinules on inner margin and armed with one subapicalsetae plumose only on outer edge. Terminal claw nearlythree times longer than the ﬁfth segment, 107 lm long,ornamented with rows of minute spinules.Swimming legs 1–4 biramous (Figs. 3a-d), with 3-segmented rami. Intercoxal sclerite present in legs 1–4and except in leg 4, ornamented with patches of spinules.Spine and seta formula.Coxae of all legs ornamented with spinules rowslaterally, as ﬁgured, and in leg 3 also with spinules in themargin. Inner coxal seta is plumose in legs 1–3 and re-duced and naked in leg 4. Except in leg 2, basal seta ofall legs long and naked. Posterior surface of legs 1–4with minute spinules (Fig. 4d).Most of the outer spines of all exopodal segmentsbilaterally serrate, terminal exopodal element setiform inleg 1, spiniform in legs 2–4 serrate laterally and withsetules medially or distally. Outer margins of exopodaland endopodal segments with setules.Leg 5 (Fig. 1d) with protopodal segment incorporatedinto somite, with outer seta located dorsally ornamentedwith spines at base, exopod slender, more than two timeslonger than wide, ornamented with spinules and armedwith two plumose setae and one naked seta.Adult maleBody cyclopiriform with broad prosome as for female(Fig. 5a). Total length, excluding caudal setae, 660 lm(645–675 lm); (all measurements based on three speci-mens). Ratio of length of prosome to that of urosome1.93:1. Ratio of lenth to width prosome 1.5:1. Urosome(Figs. 4f, 5b) consisting of ﬁve articulating units: leg 5-bearing somite, genital somite and three free abdominalsomites. Posterior margins of all somites ornamentedwith hyaline frills with serrated free margins. Surface ofurosomal somites ornamented with ﬁne spinules. Somespinules present also on dorsal surface of ﬁfth pediger-ous somite. Genital somite about 1.5 times wider thanlong, bearing genital apertures postero-laterally onventral surface (Fig. 5b). Three postgenital somites fromanterior to posterior 29.5·66 lm, 25·61.3 lm, and41·52 lm. Caudal ramus 1.7 times longer than wide,armed as in female.Appendages as for female except antennules, maxilli-peds and ﬁfth and sixth legs. Antennule (Fig. 5c) 17-seg-mented, geniculate; segmental fusion pattern as follow:1(I), 2(II), 3(III), 4(IV), 5(V), 6(VI), 7(VII), 8(VIII), 9(IX–XII), 10(XIII), 11(XIV), 12(XV–XVI), 13(XVII),14(XVIII), 15(XIX-XX), 16(XXI–XXIII), 17(XXIV–XXVIII). Geniculation located between segments 15(XIX–XX) and 16 (XXI–XXIII). Segments 1–8 each with2 setae; segment 9 with 8 setae; segments 10,11,13,14 eachwith 2 setae, segments 12 and 15 with 4 setae; segment 16with 4 setae plus one aesthetasc, segment 17 with 11 setae.Segment 10(XIII) reduced, partly overlapped by distalexpansion of compound segment 9 (IX–XII).Maxilliped (Fig. 5d) 5-segmented; comprising shortsyncoxa, long basis and distal subchela consisting ofthree free endopodal segments armed with distal claw-like element. Syncoxa with patch of ﬁne spinules atproximal angle and one medial seta; basis with oneminute seta, one small tooth-like process in proximalhalf of medial margin and some patches of ﬁne spinulesin medial and distal half of external margin. First en-dopodal segment bearing three setae, two of themTable 1Coxa Basis Exopod segments Endopod segmentsLeg 1 0-1 1-1 I-1;I-1;III,4 0-1;0-2;1,2,3Leg 2 0-1 1-0 I-1;I-1;III,I,4 0-1;0-2;1,2,3Leg 3 0-1 1-0 I-1;I-1;III,I,4 0-1;0-2;1,1+I,3Leg 4 0-1 1-0 I-1;I-1;III,I,4 0-1;0-2;1,1+I,2319Fig. 4 Asterocheres hirsutus sp. nov. Female: a, general view of the oral appendages; b, oral cone and maxillule; d, posterior surface of leg4; e, ventral view of urosome; g, ventral view of the genital double-somite. Male: c, detail of the distal segment of the maxilla and lastantennular segment; f, dorsal view of urosome320naked. Second endopodal segment armed with oneplumose seta. Third endopodal segment bearing longterminal claw plus additional apical plumose seta. Claw-like element with rows of minute spinules.Leg 6 (Fig. 5b) postero-ventral ﬂap on genital somitebearing two subequal seta, the outer naked and orna-mented with rows of ﬁne spinules.EtymologyThe species is named from the Latin hirsutus (=hirsute,hairly), alludes to the numerous spinules and setulespresent on the surface of this species.DiscussionThe genus Asterocheres contains a large number ofspecies which can be divided into two groups (Boxshalland Huys 1994). The smaller group, to which the newspecies belongs, is characterised by females with a21-segmented antennule and the larger group is char-acterised by females having an 18- to 20-segmentedantennule. According to Kim (2004), a total of tenvalid species are included in the ﬁrst group: A. bulbosusMalt, 1991; A. ﬂustrae Ivanenko and Smurov, 1997; A.jeanyeatmanae Yeatman, 1970; A. lunatus Johnsson,1998; A. minutus (Claus, 1889); A. reginae Boxshall andFig. 5 Asterocheres hirsutus sp.nov. Male, a, habitus, dorsal;b, urosome, dorsal; c,antennule; d, maxilliped321Huys, 1994; A. suberitis Giesbrecht, 1899; A. tenuicornisBrady; A. violaceous (Claus, 1889) and A. urabensisKim, 2004. Ivanenko and Smurov (1997) pointed outthat A. aesthetes Ho, 1984 was described in the text ashaving a 19-segmented antennule in the female which isdiscordant with the presence of 21 segments on theﬁgure. However, Ho (personal communication 2003)has established that the antennule of A. aesthetes has 19segments with the terminal segment indistinctly dividedinto two segments.Among these species only three, A. aesthetes,A. ﬂustrae and A. reginae, have an aesthetasc on theproximal part of the syncoxa of the maxilla, as found inA. hirsutus. Boxshall and Huys (1994) considered thischaracter as unusual in the genus since only two species,A. aesthetes and A. reginae possessed this character (seeHo 1984, Boxshall and Huys 1994). The discovery of thisaesthetasc in a new species of Asterocheres, A. ﬂustrae,and in other three genera of Asterocheridae, ChelacheresHumes, 1989, Sinopontius Boxshall, 1990 andInermocheres Boxshall, 1990, strongly suggested that thischaracteristic is probably more common within this fa-mily, as was pointed out by Boxshall and Huys (1994),but it has been overlooked (Ivanenko and Smurov1997). This is the main reason for not using this char-acteristic to distinguish the new species from its con-geners in the present paper.Asterocheres hirsutus sp. nov. may be separated fromall congeners with 21-segmented antennule by the shapeof its maxillule, with the endite being nearly ﬁve timeslonger than the palp and the caudal rami 2.5 timeslonger than wide. Furthermore, A. bulbosus, A. violaceusand A. minutus diﬀer from A. hirsutus in their possessionof 1-segmented mandibular palp. A. suberitis has a2-segmented endopod in the antenna, instead of the3-segmented endopod present in the antenna of A.hirsutus. A. tenuicornis is also readily distinguished fromthe new species, and all its congeners, by its very elon-gate caudal rami. A. jeanyeatmanae possesses only twosetae in the free segment of leg 5, instead of the threesetae of A. hirsutus. A. lunatus has four setae in the innerlobe of maxillule and the formula (1-0) in the basis of leg1, by contrast, A. hirsutus has ﬁve distal setae in theendite of maxillule and the formula (1-1) in the basis ofleg 1. The extremely ﬂattened prosome of A. reginaeserves to separate it from the new species. The maxilli-ped is 6-segmented in A. ﬂustrae and 5-segmented in A.hirsutus. The claws of the antenna, maxilla and maxil-liped of A. urabensis are smooth; however, in A. hirsutusthey are densely hairy.Acknowledgements The authors would like to thank the oﬃcersand the crew of the RV Polarstern and many colleagues for theirhelp on board during the EASIZ-III cruise. Special thanks areaddressed to Josep Maria Gili and Wolf Arntz who made possiblethe participation in the Antarctic cruise where the present materialwas collected. We would like to thank J.-S. Ho for his helpfulcomments during the preparation of this paper, and Nuria Teixidofor her valuable assistance in consulting some bibliographic refer-ences.Support for this work was provided by the Spanish CICYTprojects ANT98-1739-E, ANT99-1608-E, REN2001-4920-E/ANT,and REN 2001-4269-E/ANT.ReferencesArntz WE (1997) Investigacio´n anta´rtica en biologı´a marina: situ-acio´n actual, proyectos internacionales y perspectivas. Bol RSoc Esp Hist Nat (Secc Biol) 93(1–4):13–44Boxshall GA, Huys R (1994) Asterocheres reginae, a new species ofparasitic copepod (Siphonostomatoida: Asterocheridae) from asponge in Belize. Syst Parasitol 27:19–23Gale´ron J, Herman RL, Arnaud PM, Arntz WE, Hain S, Klages M(1992) Macrofaunal communities on the continental shelf andslope of the southeastern Weddell Sea, Antarctica. Polar Biol12:283–290Ho J-S (1984) Copepoda associated with sponges, cnidarians andtunicates of the sea of Japan. Rep Sado Mar Biol Stat NiigaraUniv 14:23–61Huys R, Boxshall GA (1991) Copepod evolution. The Ray Society,LondonIvanenko VN, Smurov AV (1997) Asterocheres ﬂustrae n. sp.(Copepoda: Siphonostomatoida: Asterocheridae) associatedwith Flustra foliacea L. (Bryozoa) from the White Sea. SystParasitol 38:111–130Johnsson R, Bustamante AO (1997) Monocheres cagarrensis sp.nov. (Copepoda, Siphonostomatoida) from Brazil. Crustaceana70(8):894–900322

Asterocheres hirsutus, a new species of parasitic copepod (Siphonostomatoida : Asterocheridae) associated with an Antarctic hexactinellid sponge

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Asterocheres hirsutus, a new species of parasitic copepod (Siphonostomatoida : Asterocheridae) associated with an Antarctic hexactinellid sponge

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