PROTIST-BRYOZOAN-CRUSTACEANHYPEREPIBIOSIS ON GONEPLAX RHOMBOIDES (LINNAEUS,1758) (DECAPODA, BRACHYURA) FROM THENW MEDITERRANEANCOAST BY GREGORIO FERNANDEZ-LEBORANS 1/ Departamentode BiologiaAnimal I (Zoologia),Facultad de Biologia, Pnta 9, UniversidadComplutense, E-28040 Madrid, Spain ABSTRACT Aprotist-bryozoan-crustaceanhyperepibiosis was observed on specimens of the brachyuran decapod Goneplaxrhomboides collectedon the NW Mediterraneancoast. The primary epibionts werectenostomate bryozoans of the species Triticella ava .Thesecondary epibionts were ciliate protists (Zoothamnium , Cothurnia, and Corynophrya ).Thebryozoans were located on thefollowing areasof thecrab: ocular orbits, maxillae, maxillipeds, chelipeds, pereiopods, dorsal carapace, ventral cephalothorax,abdomen, and carapace areas between the pereiopods. Ciliate protists were attached indistinctlyto any of the surfaces of the bryozoans. The maximum number of bryozoans per crab was943, and of ciliates per crab, 1,466. Data regarding the number of bryozoans and ciliates on eachsurface area of thecrab are presented. Statistical analysis was carried out in order to relate the variousanatomical units of the crab with the epibionts present. There was a signicant correlation betweenthe size (i.e., width) of the crab and the number of bryozoanepibionts. There also was a signicant correlation between the number of bryozoans and the number of ciliates per crab. The dataobtained were compared with those corresponding to other specimens of Goneplaxrhomboides previouslysampled in the same geographical area that showed the same ciliates, but in that case adheringdirectly to thesurface of the crab. There was a signicant correlation between specimens of G.rhomboides withand without bryozoan epibionts with respect to thenumber of individualsof Cothurnia oneach anatomical unit of the crab. In addition, there also was a signicant difference betweencrabs with and without bryozoans epibionts as tothe number of protistepibionts on each surfacearea of the crustacean. RESUMEN Unahiperepibiosis protista-briozoo-crus táceo fue observada en especí menes del decá podo braqui- uro Goneplaxrhomboides recolectadosen la costaNW delMediterrá neo. Los epibiontes primarios fueronbriozoos ctenostomados de la especie Triticella ava .Losepibiontes secundarios fueron pro- tistasciliados ( Zoothamnium,Cothurnia y Corynophrya ).Los briozoos estaban localizados en las 1/ e-mail:[email protected] © KoninklijkeBrill NV ,Leiden,2003 Crustaceana 76(4):479-497 Alsoavailable online: www.brill.nl 480 GREGORIO FERNANDEZ-LEBORANS siguientesá reasdel cangrejo: ó rbitasoculares, maxilas, maxilí pedos, quelí pedos, pereió podos, ca- parazón dorsal,cefalotó rax ventral, abdomen, y áreasdel caparazó n entrelos pereió podos. Los pro- tistasciliados estaban adheridos indistintamente a cualquiersuper cie de los briozoos. El máximo número de briozoospor cangrejo fué de 943, y eldeciliadospor cangrejo, 1.466. Se muestrandatos relativosal número de briozoosy ciliadosen cadaá reasuper cial del cangrejo. Se harealizadoun análisis estadí stico para relacionar las diversas unidades anató micas del cangrejo y losepibiontes pre- sentes.Hay una correlació n signicativa entre el tamaño (p.ej.la anchura) del cangrejo y elnú mero debriozoos epibiontes. T ambién hayuna correlació n signicativa entre el nú mero de briozoos y elnúmero de ciliadospor cangrejo. Los datos obtenidos se compararon con los correspondientes a otrosejemplares de Goneplaxrhomboides recolectadospreviamente en la misma á reageográ ca, quemostraron los mismos ciliados, aunque en este caso adheridos directamente a lasuper cie del cangrejo.Hay una correlació n signicativa entre especí menes de G.rhomboides cony sinbriozoos epibiontesrespecto al nú mero de individuos de Cothurnia encadaunidad anató mica del cangrejo. Además, hay una diferencia signi cativa entre cangrejos con y sinbriozoos epibiontes respecto al número de protistas epibiontes en cada á reade la super cie del crustá ceo. INTRODUCTION Epibiosis is acommonphenomenon in marine and,indeed, all aquatic environ- ments (Wahl,1989). W ater turbulencehas inducedthat manylight-weight organ- isms havedeveloped some typeof attachment mechanism in evolutionaryhistory. Inor onmuddy or sandybottoms, the available space is animportant factor for species needinga hard,stable substratum forgrowth. In areas with densepopula- tions, wherecompetition forsuch a substrate is intense, the use ofas yet unocup- piedsurfaces is probablyone of the advantagesgained by organisms that devel- opedthe possibility to colonizeliving substrata (Jackson,1977; Connel & Keough, 1985).Epibiosis is afacultative association oftwo organisms: the epibiontand the basibiont (Wahl,1989). The term “epibiont”includes organisms that, duringthe sessile phaseof their life cycle,are attached to the surface ofa livingsubstratum, while the basibiont lodgesand constitutes asupportfor the epibiont(Threlkeld et al., 1993).Both concepts describe ecological functions(Wahl, 1989). Bryozoansare well-knowncolonizers oflive benthicsubtrata, andhave been describedas epizonts oncrabs,isopods, gastropods, and holothurians (Colodey et al., 1980;Ingle, 1983; Moyano, 1989; Abelló et al., 1990;Mori &Manconi,1990; Cadee,1991). Bryozoans can also attach themselves to gastropodshells that lodge hermit crabs (Gordon,1972; Key et al., 1996). Therole ofciliate protists as epibionts oncrustaceans has probablyreceived less attention thanthat ofother organisms suchas hydrozoans,bryozoans, cir- ripedes,and polychaetes (Sprague & Couch,1971). Several crustacean groups, e.g.,cladocerans, copepods, cirripedes, isopods,amphipods, and decapods, include forms that are hosts formacroepibiont invertebrates (Ross, 1983),and for proto- zoanmicroepibionts ofthe phylumCiliophora: apostomatids, chonotrichids,suc- torians, peritrichs, andheterotrichids (Corliss, 1979;Small &Lynn,1985; Morado .