ANANOMALOUSSPECIMENOF SCYLLARIDESLATUS (DECAPODA,SCYLLARIDAE)
BY
N. SPANÒ1,4/,S.RAGONESE 2/ andM. L.BIANCHINI 3/ 1/ Dipartimentodi Biologia Animale ed EcologiaMarina, Università degli Studi di Messina, SalitaSperone, 31, I-98166 S. Agata(ME), Italy 2/ IstitutoAmbiente Marino Costiero – CNR, sezionedi Mazaradel V allo(TP), Italy 3/ Soc.Porto Romano & CNR, Rome,Italy
INTRODUCTION
TheMediterranean slipper lobster, Scyllarides latus (Latreille, 1803),is alarge- sized (upto 45cm total length)crustacean (Decapoda,Scyllaridae), whichis found onrockybottoms (4m to 100m depth)in the Mediterraneanand eastern Atlantic (Holthuis,1991). It is ahighlyvalued species, sometimes caughtby lobster pot andtrammel net,seldom bytrawl-net; nowadaysan occasional by-catch,it used to becommon along the south-westerncoast andthe eastern side ofSicily and alongthe NorthAfrican coast (central Mediterranean). S. latus populationsin the Mediterraneanhave, however, been depleted, due in part toindiscriminate shing bydivers (Holthuis,1991) and some concernexists aboutthe status ofmany of the local populations.For this reason,a research programmewas launchedin 1993 to evaluate the possibility ofincreasing natural populationsof the slipper lobster basedon active restockingexperiments (Bianchini et al., 1998). Duringthis programme,observations were also carried outon specimens showingvarious anomalies in orderto evaluate survival orregenerationcapacities ofthe species. This notedescribes aspecimen of S. latus that hada supernumerary limb at the fourthright pereiopod( IV (dx)). D
METHODS ANDMATERIALS
Duringthe programme“ Feasibility andassessment ofstock enhancementby restockingfor the Mediterraneanslipper lobster, Scyllarides latus ”,breedingand
4/ e-mail:[email protected] © KoninklijkeBrill NV ,Leiden,200 3 Crustaceana 76(7):885-889 Alsoavailable online: www.brill.nl 886 NOTESAND NEWS restockingexperiments werecarried outon pilot scale (Bianchini et al., 1998) on288 specimens (between100 g and1800 g bodyweight). All specimens weremeasured (carapace length, CL, to0.1 mm), weighed (body weight, BW ,to 1g),tagged with both external andinternal tags (t-tag andPIT -tag,respectively), andkept in tanks with continuoussea-water rechange;part ofthe specimens weresubsequently released in the wild.Moreover, a limb was removedfrom some specimens (IVsn, by autotomy under traction) forlater genetic analysis; monitoringof the morphologicalchanges connected with the moult was carried outonslipper lobsters that hadmoulted in aquariaand in the wild (Bianchini et al., 2001).
RESULTSAND CONCLUSION
Theanomalous specimen reportedin this note,a male, was caughton 4 De- cember1995, tagged, kept in the aquarium,and fed ad libitum with mussels andlimpets. At capture,it measured89.8 mm CL andweighed 290 g BW.On 16January 1996, the specimen moulted,showing a CLof102.8mm and380 g BWafterwards; onthis occasion,an extra limb was formedat the IVdxpereiopod level. Several irregularities inthe exoskeletonwere observed during the programme: damagedantennae, incomplete limbs, damagedclaws anduropods were all as- sumedto bearesult ofdistress, onlypartially alleviated duringthe moult that took place in some specimens. It is worthnoting that the specimen of S. latus of this note,apart fromthe extra limb at pereiopodIV dx(g. 1), otherwise showedthe basic distinctive features within the usual normof morphology for the species, and noother abnormalities. Besides amarkedlysmaller size (41mm vs.110-120 mm; table I),the extra limb didnot show any particular characteristics, either at the macroscopicor microscopic (SEM)level. Themeasurements ofthe supernumerarylimb andthe homologousregular ones (IV dx andIV sn) are comparedin table I. Theregenerative capability ofmany parts ofthe bodyafter damageor autotomy is awell knownphenomenon in crustaceans (Vernet &Charmantier-Daures,1994). Infact, variousanomalies in specimens ofthe spinylobster Panulirusargus (Latreille, 1804)(cf. Davis, 1981) have been observed, as in variousother decapod species suchas Porcellanaplatycheles (Pennant,1777) and Cancerpagurus L., 1758(cf. Lawton, 1989). In particular in the case ofa loss ofappendages, however, asingle moultusually is enoughto forma newappendage, be it smaller than normal.In general, several moults are requiredbefore the full size ofthe limb is reachedagain (Phillips et al., 1980).