Publishedin collaboration with the University of Bergenand the Institute of Marine Research,Norway Re-descriptionsof Caprellalinearis (Linnaeus,1767) and C.septentrionalis Kro¨yer,1838 (Crustacea: Amphipoda: Caprellidea) from Scotland, with an on- togeneticcomparison between the species anda studyof theclinging behaviour Jose´ManuelGuerra-Garc ´a SARSIA Guerra-Garc ´aJM.2002. Re-descriptions of Caprellalinearis (Linnaeus,1767) and C.septentrionalis Kro¨yer,1838 (Crustacea: Amphipoda:Caprellidea) from Scotland, with an ontogenetic comparison between thespecies anda studyof theclinging behaviour. Sarsia 87:216–235. Caprellalinearis (Linnaeus,1767) and C.septentrionalis Kro¨yer,1838 are re-describedbased on specimens collectedfrom the coasts ofScotland. Mature males of C. linearis differclearly fromthose of C.septentrionalis mainlyin the features ofantenna1 andgnathopod 2. The pair of lateral projections presenton pereonite 5 infemales of C. linearis is lackingin females of C.septentrionalis . The gnathopod2 propodusis widerand the genital openings more setose infemales of C.septentrionalis than in C. linearis.Thearrangement ofthebody projections and the abdomen during development is quitesimilar in C. linearis and C.septentrionalis .Forboth species thepredominant mode of attachment tothesubstrate is theupright posture and feeding is by ltering,frequently using grooming behaviour. These species presentbasically the same geographicaldistribution, along the North Atlantic, Boreal andArctic regionsand they are notvery speci c inchoosingtheir substrate. J.M. Guerra-Garc ´a,Laboratoriode Biolog ´aMarina,Departamento de Fisiolog ´a y Biolog´a Animal, Facultadde Biolog ´a,Universidad de Sevilla,Apdo. 1095, E-41080, Sevilla, Spain. E-mail:jmguerra@ us.es Keywords: Caprellalinearis ; Caprellaseptentrionalis ;Caprellidea;re-descriptions; clinging beha- viour;ecology; biogeography; Scotland. INTRODUCTION subspecic variants.Although C. linearis and C. septentrionalis havebeen found frequently in North Duringa shortstay at the Gatty Marine Laboratories, St Atlanticwaters, they have never been described in Andrews,Scotland, several samples of theCaprellidea detail.Furthermore, from the extensive literature, only fromthe east and west coasts of Scotland(Fig. 1) were thedescriptions of McCain (1968) as part of a general collected.The intertidal rocky areas of St Andrews, studyof the Caprellidea of thewestern North Atlantic, Boarhillsand Kingsbarns (east coast) were exclusively areof most signi cance. inhabitedby Caprellasepten trionalis Kro¨yer,1838. On Todifferentiate C. linearis from C.septentrionalis thewest coast (Clachan Seil, near Oban) an important completedescriptions with detailed guresof antennae, populationof C. linearis (Linnaeus,1767) was found. mouthparts,gnathopods, pereopods and abdomen are Thenomenclature of C. linearis and C.septentrio- necessary.These descriptions, based on the material nalis hastraditionally been one of the most confused in collectedalong the Scottish coasts, are included in the theCaprellidea literature. McCain & Steinberg(1970) presentpaper. Furthermore, guresof thelateral view, pointedout that these species were easily confused and, gnathopod2 andabdomen during the different stages of therefore,many of the references could be questionable. developmentand data on clinging behaviour are Smaldon(1990) reported that no simple distinction presentedhere with the purpose of comparisonbetween couldbe made between the two species. For C. thetwo species. septentrionalis ,avarietyof body forms based mainly onthebody projections have been recognized since its MATERIALAND METHODS originaldescription. Mayer (1890, 1903) considered the differentforms as variants of the same species. Never- Samplesof various types of substrata on which theless,Stephensen (1940) treated several of these caprellidswere expected to inhabit were carefully formsas distinctspecies or subspecies.McCain (1968) detachedfrom rocks of intertidal areas along the east foundnumerous intergradations between the forms and andwest coasts of Scotland (Fig. 1). The intertidal suggestedthat they probably represented only infra- zonesat St Andrews,Boarhills and Kingbarns (56 °15’N # 2002Taylor & Francis Guerra-Garc ´a–Comparisonbetween Caprellalinearis and C. septentrionalis 217 clingingbehaviour was also studied. For the behaviour- alstudies, 10 mature specimens ( ve males and ve females)of each species were selected prior to preservationand individuals were placed in a Petridish lledwith seawater. The methods used for measuring theclinging behaviour in the present study are explainedin detail in Takeuchi & Hirano(1995). The gureswere drawn using a binocularmicroscope withthe aid of acameralucida. Permanent preparations ofthe mouthparts were made using polyvinyl lactophe- nol.Fifty mature males and 50 maturefemales of each specieswere measured under the microscope. The body lengthwas calculated as the sum of the head and pereonitelengths. Specimens of bothspecies have been depositedin the Museo Nacional de CienciasNaturales, Spainwith the follow catalogue numbers: MNCN 20.04/4660for C.septentrionalis and20.04/ 4661for C. linearis.Withthe purpose of comparison, the type material(syntypes from Greenland) of C.septentrio- nalis fromthe Zoological Museum, University of Copenhagen(ZMUC-CRU-8059) was consulted. Type materialdoes not exist for C. linearis.Inthiscase, non- typematerial from Nordso ¨en,O ¨ rsted,Denmark (ZMUC uncatalogued)was examined. Fig.1. Location of the sampling stations on the coasts of RESULTSAND DISCUSSION Scotland. SYSTEMATICS Caprellalinearis (Linnaeus,1767) 02°30’W)areareas exposed to waveaction. The algae Cancerlinearis (Linnaeus1767: 1056) communityis dominated by the brown seaweed Fucus Oniscusscolopendroides (Pallas1772: 80, plate 4, g. serratus Linnaeus,1753 and several species of the 15 a–c) genera Polysiphonia and Ceramium.ClachanSeil, Squillalobata (Mu¨ller1776: 197) alongthe west coast, is a verysheltered tidal strait of Squillaquadrilobata (Abildgaard1788: 21– 22, plate approximately30 mwideand 1 kmlong separating Seil 56, gs 4–6) Island (56°20’N 05°35’W)fromthe Argyll mainland. Gammarusquadrilobatus (Abildgaard1789: 58, plate Thereare tidal sills at bothends of thenarrows, and as a 114, gs11,12) result,the spring tides ebb to the same level between the Cancer(Gammarellus) linearis (Herbst1793: 142– 144, sillsirrespective of the open coast uctuations;hence, plates99, 106) theenclosed narrows are never immersed. The domi- Cancerlinnearis (Linnaeus1800: 761) nantalga is also F. serratus;largeamounts of Caprellalinearis (Mayer1882: 58– 62, gs17– 19, plate bryozoans(principally Electrapilosa Linnaeus,1767) 4, g.32;Koehler 1885: 98– 99, 117;Sokolowsky 1900: andhydroids are attached to thesurface of theseaweed 162,plate 3, g.16; Chevreux & Fage1925: 456– 457, andare considerably more abundant than at St g.434;McCain 1968: 30– 33, gs14,22, 51; Laubitz Andrews,Boarhills and Kingsbarns. 1972:35– 37, plate 7; Smaldon 1990: 448, g.9.48; Thecollected material was brought back to theGatty Larsen1998: 82, g.2) MarineLaboratories and transferred into a shallow Caprellalaevis (Goodsir1842: 189– 190, plate 3, gs4, trainer lledwith seawater. The caprellids were hand 5) pickedand xedin a 10%seawater– formalin solution Caprellalobata (Bate1856: 60; 1862:354, plate 55, g. andthen preserved in 70%ethanol. 8) Inan attempt to elucidate if the method of attachment Caprellalinearis f. gullmarensis (Mayer1903: 112, tothe substrate could differentiate these species, the plate8, g.20) 218 Sarsia 87:216-235– 2002 Fig. 2. Caprellalinearis (Linnaeus,1767) from Scotland. Lateral view.a. Male.b. Female. Scale bars:1 mm. Caprellalinearis f. distalis (Mayer1903: 113, plate 4, Materialexamined gs 27, 28) Eightmature males, seven mature females, seven prematurefemales and one juvenile collected from Typelocality hydroidsattached to the seaweed F. serratus at the “Habitatin Oceano Europaeo” (Linnaeus 1767). intertidalarea of ClachanSeil, west coast of Scotland, May 2000. Typematerial Additionalmaterial examined Notdesigned. Non-typematerial (12 mature males, three mature Guerra-Garc ´a–Comparisonbetween Caprellalinearis and C. septentrionalis 219 Fig. 3. Caprellalinearis (Linnaeus,1767) from Scotland. Male. a. Antenna1. b.Antenna2. c. Gnathopod1. d.Gnathopod2. Scale bars:A: 1mm (a); B:1mm (b);C: 0.3mm (c); D: 1 mm (d). females,14 premature females, 11 juveniles) from setaeon peduncular articles 3 and4. Flagellum two- Nordso¨en,O ¨ rsted,Denmark. articulate.Proximal article with six pairs of swimming Description(mature male “ a”from Clachan Seil, setae. Scotland).Lateral view (Fig. 2a). Body length 10.1 mm. Gnathopod1 (Fig.3c) basis a littleshorter than Headwith a smallmid-dorsal rounded projection. ischiumto carpus combined. Carpus with a pairof Pereonites1 and2 elongate.Pereonite 2 thelongest. proximalgrasping spines. Grasping margin of palm Pereonite3 witha roundtubercle posteriorly. Pereonite propodusand dactylus serrated. Dactylus bi d distally 5withtwo pairs of small round projections. Pereonites carryinga simpleseta. 6and7 withone pair of small acute projections. Gills Gnathopod2 (Fig.3d) basis inserted posteriorly on elongate,length about 3.3 times width. pereonite2, about0.7 times as long as pereonite2 and Antenna1 (Fig.3a) nearly 0.5 the body length. 0.2the body length. Basis with a distalacute projection. Articles2 and3 ofpeduncle setose. Article 2 the Propodusslender, length about 3.0 times width, bearing longest,about 1.5 times longer