The Caprellidea (Crustacea: Amphipoda) from Mauritius Island, Western Indian Ocean

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1 Zootaxa : 1-24 (2003) Copyright 2003 Magnolia Press ISSN (print edition) ZOOTAXA ISSN (online edition) The Caprellidea (Crustacea: Amphipoda) from Mauritius Island, Western Indian Ocean JOSÉ M. GUERRA-GARCÍA Laboratorio de Biología Marina, Departamento de Fisiología y Zoología, Facultad de Biología, Universidad de Sevilla, Avda Reina Mercedes 6, 41012, Sevilla, Spain jmguerra@us.es Abstract The caprellidean fauna of Mauritius was investigated. Sixteen stations were selected around the island and different substrata (including algae, seagrass, sponges, hydroids, ascidians, echinoderms, encrusted dead corals, coral rubble, fine and coarse sediments) were sampled. The study reports seven species in six genera, five of which are new records for the island and one, Metaprotella mauritiensis is described as new to science. Metaprotella sandalensis Mayer, 1898 was the most common species in the coral reef system surrounding Mauritius. Key words: Crustacea, Amphipoda, Caprellidea, systematics, new species, Mauritius Introduction There have been few investigations on the Caprellidea of the southern and western Indian Ocean. Recently, Laubitz (1995) studied the caprellid material of the French Expedition collections from the southern and western Indian Ocean islands of St Paul and Amsterdam, Réunion, Mayotte and Agalega, along with small collections from Madagascar. She found 21 species of caprellid of which seven were new to the region, and another seven were new to science, including four new genera. Larsen (1997) described a new species of the genus Metaprotella Mayer, 1890 from Zanzibar Island. The lack of studies in the Western Indian Ocean is specially significant in Mauritius Island. Studies on the amphipod fauna of Mauritius are sparse, dating back to the 19th century when Templeton (1836) gave brief morphological descriptions of a few species. He described Caprella scaura, the only caprellid species which has been recorded so far at Mauritius Island (McCain & Steinberg, 1970). Since Templeton s (1836) contribution amphipod studies in Mauritius had been exclusively focused on the Gammaridea. Ledoyer Accepted: 23 June 2003; published: 4 July

2 (1978) analysed samples of gammarids collected along the north-west coast of Mauritius at depths ranging from 0 to 25 metres and recorded 89 species of which 24 were new to science. Recently, Appadoo & Steele (1988) made extensive collections of gammarids around the island reporting 79 species, 41 of these being new records for the island and 19 being undescribed species and, more recently, several gammaridean genera from Mauritius have been studied (Appadoo et al. 2002a, b). Taking into account that only one caprellidean species had been recorded from Mauritius Island, the present study was undertaken to characterise the caprellid diversity around the island. Material and methods Study area The republic of Mauritius (Fig. 1), situated in the south-west Indian Ocean, consists of one major island, Mauritius (19º59 20º32 S, 57º18 57º47 E), in which the present study was conducted, and a number of outer islands and islets including Rodrigues, Cargados Carajos Archipelago, Agalega, Tromelin and the Chagos Archipelago. Mauritius is of volcanic origin and has a land area of 1865 km 2, a coastline of 200 km, and 150 km of enclosing coral-reef lagoons with a total area of about 245 km 2. The coastline is bathed by the waters of the south equatorial current and the island has shores with very varied exposure to wave action. Around Mauritius Island different habitats can be found (reef flats and slopes, algae and seagrass beds, coral rubble, fine and coarse sediments, intertidal boulders, etc.) Sampling procedure The sampling programme targeted caprellids and was conducted at Mauritius Island during July Sixteen sites were sampled around the island (Fig. 1) representing a wide diversity of habitats. The following abbreviations of the sampling localities have been use throughout the text: AB: Albion, BB: BlueBay,BO: BelOmbre,BT: Baie du Tombeau, CM: CapMalheureux, FF:FlicenFlac,GB: Grand Baie, IB: Ile aux Benitiers, PB: Pte aux Biches, PL: Port Louis, PS: Pte aux Sables, QS: Quatre Soeurs, TA: Tamarin, TD: Trou D Eau Douce, WM:Wolmar,WR: WhaleRock. All the sites were sampled from the intertidal to 5 metres deep using snorkelling and SCUBA diving except for the site FF and WR where the sampling was carried out at 15 and 35 metres respectively. About 200 samples of potentially suitable substrata for the Caprellidea were collected, including algae (24 species), sea grasses (5 species), sponges (four species), hydroids (four species), ascidians (two species), encrusted dead corals, coral rubble, fine and coarse sediments. Although the echinoderms and most of the hard corals were not sampled directly, they were checked for caprellids in situ. The most Magnolia Press GUERRA-GARCÍA

3 abundant algae were Halimeda incrassata (Ellis) Lamouroux, 1816, Padina commersonii Bory de Saint-Vincent, 1828, Sargassum spp., Turbinaria spp. and the dominant sea grasses were Halophila ovalis Hook, 1858, Halodule uninervis (Forsskal) Ascherson, 1882 and Syringodium isoetifolium (Ascherson) Dandy, The soft-bottom samples were collected by hand using mesh bags and a plankton net that was dragged along the bottom after digging up the bottom. The remaining substrata were placed in plastic bags. To avoid damaging the specimens by sieving the sediment, the caprellids were separated from the sediment by elutriation. All the samples were fixed in 95% ethanol. Caprellids were separated under a binocular microscope. ZOOTAXA Whale Rock (WR) Grand Baie (GB) Cap Malheureux (CM) Pte aux Biches (PB) Baie du Tombeau (BT) Port Louis (PL) Pte aux Sables (PS) Albion (AB) Flic en Flac (FF) Wolmar (WM) Tamarin (TA) MAURITIUS Trou D Eau Douce (TD) Quatre Soeurs (QS) Ile aux Benitiers (IB) Blue Bay (BB) Bel Ombre (BO) FIGURE 1. Map of Mauritius showing the sampling localities. 10 km MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 3

4 The type material of Metaprotella mauritiensis is deposited in the Museo Nacional de Ciencias Naturales (MNCN), Madrid, Spain, and additional specimens are deposited at the Albion Fisheries Research Center, Mauritius (AFRC). TAXONOMY Family Caprellidea Leach, 1814 Caprella scaura Templeton, 1836 (Fig. 2) Abbreviated synonymy Caprella scaura Templeton, 1836: , pl. 20, fig. 6; Mayer, 1890: 70 73, pl. 4, figs , pl. 6, fig. 41, pl. 7, figs. 2, 35 36; Mayer, 1903: , pl. 5, figs , pl. 10, fig. 11; McCain, 1968: 40 44, figs , 55. Caprella nodosa Templeton, 1836: , pl. 21, fig. 7. Caprella cornuta Dana, 1853: Caprella attenuata Dana, 1853: A more extensive synonymy for this species is found in McCain & Steinberg (1970). Material examined. GB: 1 male, 1 female, on Sargassum sp.,1m,13july2002;ps: 16 males, 28 females, 16 juveniles, on Gracilaria sp.,1.5m,24july2002;ab: 1male,1 female on Syringodium isoetifolium, 1, clinging brown algae, intertidal, 9 July Remarks. This species is distributed widely in temperate regions all over the world (McCain, 1968; McCain & Steinberg, 1970). Caprella scaura was described by Templeton (1836) based on material from Mauritius, southern Indian Ocean. Seven varieties have been described by Mayer (1890, 1903) and Utinomi (1947). Of these varieties, McCain (1968) established C. californica Stimpson, 1857 as a different species, and kept the others varieties under the name Caprella scaura. The specimens examined in the present study agree with the original description, the figures and descriptions of Caprella scaura typica Mayer, 1890 from Brazil (Mayer, 1890; Arimoto, 1976) and of Caprella scaura of McCain (1968) from the western North Atlantic. This species occurs on a wide variation of substrata indicating no specific habitat selection. Caprella scaura has been frequently recorded in association with the bryozoan Bugula neritina (Linnaeus, 1758), erect bryozoans of the genus Scrupocellaria, with the seaweeds Sargassum spp. and Cystoseira spp. and the sea grasses Halodule uninervis and Halophila ovalis (Lim & Alexander, 1986). Takeuchi & Hino (1997) found the species attached to the sea grasses Zostera marina (Linnaeus, 1753), and Serejo (1998) reported the presence of the species clinging to the sponge Dysidea fragilis (Montagu, 1818). In Coquimbo, C. scaura has been found living on Bugula neritina and the sea weeds Polysiphonia spp. and Gracilaria spp. (Guerra- García & Thiel, 2001). Recently Guerra-García (personal observation) studied specimens from Caulerpa sp. and Posidonia australis (Hooker, 1858) Caprella scaura is one caprel Magnolia Press GUERRA-GARCÍA

5 lid for which the behaviour is well-described and the species has been described to have parental care(lim & Alexander, 1986; Aoki, 1999; Schultz & Alexander, 2001). ZOOTAXA FIGURE 2. Caprella scaura Templeton, Lateral view. A, male; B, female. Scale bar: 1 mm. MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 5

6 FIGURE 3. Hemiaegina minuta Mayer, Lateral view. A, male; B, female. Scale bar: 1 mm Magnolia Press GUERRA-GARCÍA

7 Hemiaegina minuta Mayer, 1890 (Fig. 3) Hemiaegina minuta Mayer, 1890: 40, pl. 1, figs , pl. 3, figs , pl. 5, figs , pl. 6, figs. 13, 33 34, pl. 7, fig. 4; McCain, 1968: 61 64, figs ; McCain & Steinberg, 1970: 51; Gable & Lazo-Wasem, 1987: 637; Müller, 1990: 836; Serejo, 1997: 631, fig. 1. Hemiaegina quadripunctata Sundara Raj, 1927: , pl. 18. Hemiaegina costai Quitete, 1972: , pls ZOOTAXA Material examined. BT: 3 males, 5 females, 2 juveniles, on Turbinaria ornata, 3m,9 th July Remarks. Hemiaegina minuta is widely distributed in tropical and temperate waters of the world oceans (Müller, 1990). Hemiaegina minuta has been collected from Sargassum sp and taken in plankton tows (McCain & Steinberg, 1970). Müller (1990) reported H. minuta preferring more-or-less exposed reef locations. Recently, the author has studied material of H. minuta from Papua New Guinea living on Dictyota sp, Halimeda sp, Gracilaria sp, Galaxaura sp., and Amansia glomerata (Agardh) Norris, 1979; and also from Queensland and north-western Australia on many different substrata: green algae such as Halimeda spp, brown and red algae, sponges, tunicates, Posidonia anddeadcorals encrusted with algal turf. and under small boulders (Guerra-García, personal observations). Metaprotella mauritiensis n. sp. (Figs. 4 7) Material examined. Holotype male (MNCN 20.04/5418a), living on fine sediment among soft corals of the genus Dendronephthya, 2 3 m, 20 July 2002 (CM). Allotype female (MNCN 20.04/5418b), collected together with the holotype male. Paratypes: 6 males, 5 females, 2 juveniles (MNCN 20.04/5418c), collected together the holotype; 1 male, 3 females, 1 juvenile deposited at the Albion Fisheries Research Center (AFRC), collected together the holotype Type locality. Cap Malheureux, Mauritius (20º18 S, 57º47 E) Etymology. The species bears the name of the Island where it was found, Mauritius. Diagnosis. Head and body smooth. Pereonites 6 and 7 fused. Suture between the head and pereonite 1 well marked. Flagellum of antenna 2 with 2 articles; swimming setae absent. Mandibular palp 3-articulate; setal formula for terminal article 1-2-1; molar present. Pereopods 3 and 4 each reduced to minute round article. Pereopods 5 7 without grasping spines. Abdomen of male with a pair of uniarticulate appendages. Description Mature male (holotype, MNCN 20.04/5418a). Body length 3.4 mm. Suture between head and pereonite 1 present; pereonite 3 longest. Pereonites 6 and 7 fused. Head and body smooth. Eye distinctive. Gills on pereonites 3 and 4, oval, length about 2 times the width; first pair 1.2 times as long as the second pair. MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 7

8 FIGURE 4. Metaprotella mauritiensis n. sp. Lateral view. A, holotype male; B, paratype male; C, allotype female. Scale bar: 1 mm Magnolia Press GUERRA-GARCÍA

9 FIGURE 5. Metaprotella mauritiensis n. sp. A, maxilliped; B, lower lip; C, upper lip; D, right mandible; E, left mandible; F, maxilla 2; G, maxilla 1. Scale bars: 0.1 mm. MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 9

10 FIGURE 6. Metaprotella mauritiensis n. sp. A D, male. A, antenna 1; B, antenna 2; C, gnathopod 1; D, gnathopod 2. E, female gnathopod 2. Scale bars: A,C,E: 1 mm; B: 0.2 mm; D: 0.5 mm. FIGURE 7. Metaprotella mauritiensis n. sp. A F, male. A, pereopod 3; B, pereopod 4; C, pereopod 5; D, pereopod 6; E, pereopod 7; F, ventral view of the pereonites 6 and 7 (fused) showing the abdomen. G, female, ventral view of the pereonites 6 and 7 (fused) showing the genital openings (between pereonite 5 and pereonite 6) and the abdomen. Scale bars: A, B: 0.1 mm; C G: 0.2 mm Magnolia Press GUERRA-GARCÍA

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12 Mouthparts. Upper lip symmetrically bilobed; each lobe carrying a distal row of minute setulae. Mandibles with palp; mandibular molar process strong; left mandible with incisor and lacinia mobilis divided into 5 teeth, followed by 3 submarginal pectinate setae; right mandible incisor divided into 5 teeth followed by lacinia mobilis divided into 2 teeth, one wider and minutely serrate, followed by 2 pectinate setae; palp with 3 articles; article 1 lacking setae; article 2 with 2 setae on left mandible and without setae on the right mandible; article 3 with setal formula Inner lobes of the lower lip well demarcated, rectangular, with margin smooth. Maxilla 1 outer lobe carrying 7 bifurcate spines; distal article of palp with 4 teeth and 5 robust setae on apical end, and 3 setae medially. Maxilla 2 outer lobe rectangular, carrying 7 setae; inner lobe oval, with 6 setae distally. Maxilliped inner plate oval, with 3 simple setae and 1 robust setae (like a tooth) on distal margin; outer plate larger than inner, inner margin setulose, bearing 1 seta apically; article 3 of the palp without distal expansion. Antenna 1 a little shorter than the body length; article 2 of the peduncle the longest; flagellum 7-articulate. Antenna 2 without swimming setae; peduncular article 1 without acute distal projection; flagellum 2-articulate. Gnathopod 1 basis a little shorter than ischium to carpus combined; propodus oval with proximal grasping spine, palm margin almost smooth; dactylus minutely setose on inner margin. Gnathopod 2 inserted on anterior half of pereonite 2; basis slender, as long as pereonite 2; propodus elongate, length about 2 times of width, with a minute grasping spine on small proximal projection, and another two triangular projection distally; dactylus with sparse setulae medially on the inner margin. Pereopods 3 4 reduced to a minute round article. Pereopods 5 7 (from male paratype, MNCN 20.04/5418c) similar to each other, smooth, without grasping spines. Penes small, situated laterally. Abdomen with a pair of 1-articulate appendages, pair of lobes and single dorsal lobe with pair of plumose setae. Mature female (allotype, MNCN 20.04/5418b). Body length 2.3 mm. Differences to the male: palm of gnathopod 2 straight, without projections. Oostegites on pereonite 3 and 4 with inner margin setose. Genital openings setose. Abdomen with pair of lateral lobes and single dorsal lobe. Remarks. The genus Metaprotella has been recently studied by Larsen (1997) and Guerra-García (2002a). Metaprotella mauritiensis n.sp. has been assigned to the genus Metaprotella mainly due to the fusion of the pereonites 6 and 7, but this new species can be easily distinguished from the remaining species of Metaprotella by the absence of grasping spines on the pereopods 5 7, the tiny pereopods 3 and 4 and the shape of the male gnathopod 2. The new species is small in size (males: 2.21 ± 0.73 mm (mean ± standard deviation), Magnolia Press GUERRA-GARCÍA

13 range ( mm); females 1.82 ± 0.43 ( )). Curiously, although samples of sediment have been collected around the whole island, M. mauritiensis has been only found in the soft bottoms from the northern area, Cap Malheureux. The sediment in this area was surrounded by soft corals of the genus Dendronephthya. Akeytospecieslevel, modified from Larsen (1997) and Guerra-García (2002a) is provided as a basic comparison among Metaprotella species. ZOOTAXA Key to the world species of Metaprotella (modified from Larsen, 1997 and Guerra-García, 2002a) 1. Propodus of pereopods 5 7 without grasping spines. Pereopods 3 and 4 extremely reduced, almost absent. Body length of adults less than 3.5 mm. M. mauritiensis n. sp. Propodus of pereopods 5 7 with a pair of grasping spines. Pereopods 3 and 4 not reduced, with 1 or 2 articles. Body length of adults more than 3.5 mm Pereopods 3 and 4 with 2 articles...m. tanzaniensis Guerra-García, 2002 Pereopods 3 and 4 with 1 article Propodus of male gnathopod 2 with an acute distal projection M. makrodactylos Stebbing, 1910 Propodus of male gnathopod 2 without acute distal projection Male gnathopod 2 ventral margin of propodus with several conspicuous rows of dense setae. Dactylus of male gnathopod 2 decreasing in width midway......m. unguja Larsen, 1997 Male gnathopod 2 ventral margin of propodus without conspicuous rows of setae. Dactylus of male gnathopod 2 not decreasing in midway Suture between head and pereonite 1 absent...m. sandalensis Mayer, 1898 Suture between head and pereonite 1 present Body dorsally smooth... 7 Body with dorsal projections Pereonite 3 with one forward pointing spine laterally... M. problematica Mayer, 1890 Pereonite 3 lacking laterally spines... M. hummelincki McCain, Male gnathopod 2 lacking spines on basis...m. africana Mayer, 1903 Male gnathopod 2 with spines on basis Pereopods 3 and 4 about 1/4 the length of the gills. Basis of male gnathopod 2 with dorsomedial spines...m. excentrica Mayer, 1890 Pereopods 3 and 4 about 1/2 the length of the gills. Basis of male gnathopod 2 lacking dorsomedial spines... M. haswelliana (Mayer, 1882) MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 13

14 FIGURE 8. Metaprotella sandalensis Mayer, Lateral view. A, male; B, female. Scale bar: 1 mm Magnolia Press GUERRA-GARCÍA

15 Metaprotella sandalensis Mayer, 1898 (Fig. 8) Metaprotella sandalensis Mayer, 1898: 53 56, figs. 1 6; Mayer, 1903: 40 42, pl. 1, figs , 34 36, pl. 6, figs , pl. 9, figs.16 17, 44, 60 (included f. ralumiana, singaporensis, dolichocephala, gisserana, amboinensis, typica); Müller, 1990: , figs ZOOTAXA Material examined. BT: 36 males, 41 females, 21 juveniles, on Turbinaria ornata, 3m,9 July 2002; AB: 1 males, 3 females, 1 juvenile, on T. ornata, 2 m, 12 July 2002; IB: 4 males, 7 females, 3 juveniles, on T. ornata, 4 5 m, 18 July 2002; BB: 1maleonJania sp., 2 3 m, 30 July Remarks. Metaprotella sandalensis has been recently redescribed in detail by Müller (1990) and the specimens from Mauritius agree with this complete redescription. This species is very common in shallow waters of the tropical Indo-Pacific Ocean (Müller, 1990). On Mauritius Island, M. sandalensis is also the most abundant and common species. The genus Metaprotella has been recently revised by Larsen (1997) and there are complete keys to the species of Metaprotella (Larsen, 1997; Guerra-García, 2002a). A molecular approach would probably reveal the existence of cryptic species inside a complex under the name M. sandalensis. In a recent study at Lizard Island, Great Barrier Reef, Australia, the author found a great variety of morphological forms and habitats for M. sandalensis. Further genetic studies are necessary to investigate if the variation among specimens of M. sandalensis is intra- or interspecific. Müller (1990) reported that M. sandalensis prefers not very exposed locations. Study of material from Australia and Papua New Guinea has revealed that the species can live in many different substrate, having been found on algae, gorgonians, soft corals, sponges, ascidians, soft bottoms, coral rubbles, sea grasses, hydroids, bryozoans and mangroves (Guerra-García, personal observation). Noculacia sp. (Fig. 9) Material examined. BT: 1 female, 2 juveniles, on Turbinaria ornata, 3m,9July2002. Remarks. The material examined was in very poor condition. The specimens have been assigned to the genus Noculacia on the basis of the combination of the following characteristics: mandibular molar absent, palp three-articulate, setal formula 1-x-1, gills on pereonites 3 and 4, pereopods 3 and 4 two-articulate. Recently, Guerra-García (2002b) revised the genus Noculacia, presently composed by three species, Noculacia africana Guerra-García, 2002, N. australiensis Guerra-García, 2002 and N. bullata Mayer, 1903.The female from Mauritius seems to be close to N. africana but there are slight differences in the body spination and the structure of the pereopods 3 and 4. The lack of sufficient material has prevented assigning the Mauritian specimens to Noculacia africana or to a new species of Noculacia. MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 15

16 FIGURE 9. Noculacia sp. Female lateral view. Scale bar: 1 mm Magnolia Press GUERRA-GARCÍA

17 FIGURE 10. Orthoprotella australis (Haswell, 1880). Lateral view. A, male; B, female. Scale bar: 1 mm. MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 17

18 Orthoprotella australis (Haswell, 1880) (Fig. 10) Protella australis Haswell, 1880: 276, pl. 12, fig. 4; Mayer, 1890: 23. Orthoprotella australis Mayer, 1903: 35 36, pl. 1, figs , pl. 6, figs. 45, 47 49, pl. 9, figs. 14, 37, 57. Material examined. WR: 6 males, 8 females, 18 juveniles, clinging on hydroids, 35 m, 27 July Remarks. This species of Orthoprotella can be easily distinguished from the other species in the genus by the presence of two acute projections on the head. The species is being redescribed from specimens collected in New South Wales (Takeuchi, personal communication). Studying Mauritius this species has been found at depths of more than 20 meters in association with hydroids. In a study of the Caprellidea from the Great Barrier Reef, Guerra-García (personal observations) found many specimens of O. australis living on hydroids (mainly Macrorhynchia philippina Kirchenpauer, 1872 and Salacia sp.) and the tunicate Polycarpa sp. In the Northern Territory, Australia, O. australis was also found living on algae and sediments (Guerra-García, personal observations). Paracaprella sp. (Fig. 11) Material examined. GB: 1 male, 1 premature female, 3 juveniles, clinging on sponges under boulders, intertidal, 13 July Remarks. The present specimens have been identified as Paracaprella mainly on the basis of the presence of pereopods 3 and 4 reduced to 2 articles, antenna 2 without swimming setae and flagellum 2-articulate, and abdomen of the male with a pair of appendages and a pair of lobes. The specimens from Mauritius are closest to Paracaprella tenuis Mayer, 1903 on the basis of the absence of dorsal and lateral body projections and the basis of gnathopod 2 not expanded (McCain 1968). Paracaprella from Mauritius and P. tenuis also resembles Paracaprella pusilla Mayer, 1890, but the males of P. pusilla have a large sharp-pointed projection on the antero-ventral margin of pereonite 2, a proximal knob on the basis of gnathopod 2 and setae on the dactylus of gnathopod 2, which are absent in the male of Paracaprella sp. from Mauritius and P. tenuis. Takingintoaccount that the material from Mauritius is scarce and that the genus Paracaprella is still in need of further taxonomic revision, we have identified these specimens as Paracaprella sp at the moment. Differences in eye size and the propodus of gnathopod 2 prevent identification the Mauritian specimens as P. tenuis. FIGURE 11. Paracaprella sp. Lateral view. A, male; B, female. Scale bar: 1 mm Magnolia Press GUERRA-GARCÍA

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20 Paracaprella tenuis have been collected from the western coast of North Atlantic (McCain, 1968) and recently, Guerra-García (2002c) redescribed the species based on specimens collected from the Tanzanian coast. The specimens collected in Tanzania differed in some characteristics from the type material of the western coast of North Atlantic but these differences were considered intraspecific variation by Guerra-García (2002c). According to these identifications, P. tenuis show a unique distribution (western coast of North Atlantic and tropical area of the Indian Ocean). This rare distribution could indicate that the specimens from Tanzania do not belong really to P. tenuis and the small morphological differences are interespecific and not intraspecific, or that P. tenuis really possess a wider distribution area, maybe cosmopolitan, but it has not been collected yet from many zones; this species is not very conspicuous and usually the specimens are covered by detritus and could have been unnoticed in many areas. Molecular analysis would be helpful in clarifying species boundaries in the genus Paracaprella and specifically to elucidate what is and what is not P. tenuis. Key to the Caprellidae of Mauritius The species key provided can be used without dissection. McCain (1968) includes a lateral view of a generalised caprellid showing the names of the different parts. Consultation of these figures could be useful for the use of the key 1. Pereopods 3 and 4 absent.. Antenna 2 setose... Caprella scaura (Fig.2) Pereopods 3 and 4 present, although very reduced. Antenna 2 not setose Pereonites 6 and 7 fused... 3 Pereonites 6 and 7 not fused Body with dorsal projections...metaprotella sandalensis (Fig.8) Body dorsally without dorsal projections... Metaprotella mauritiensis (Figs.4 7) 4. One or two dorsal projections on the head... 5 Head smooth without projections Two acute projections dorsally on the head. Pereopods 3 and 4 reduced but visible......orthoprotella australis (Fig.10) Only one dorsal projection on the head. Pereopods 3 and 4 very reduced. Very small size... Noculacia sp (Fig.9) 6. Gnathopod 2 setose, pereonites 5 7 short and robust. Abdomen not visible in the lateral view...paracaprella sp (Fig.11) Gnathopod 2 not setose, pereonites 5 7 elongate. Abdomen projections visible in the lateral view... Hemiaegina minuta (Fig.3) Magnolia Press GUERRA-GARCÍA

21 Discussion Mauritius is an isolated volcanic island formed during the early Pliocene about 7.8 million years ago and amphipods may have colonised the island by jump dispersal, a process which involves the movement of propagules across uninhabitable regions (Myers & Giller, 1988; Appadoo & Steele, 1998). The lack of a planktonic larval stage suggests that amphipods, specially caprellids are distributed passively by clinging to floating materials, rafting on marine plants, debris or logs (Barnard, 1976; Myers, 1993; Takeuchi & Sawamoto, 1998; Thiel et al., 2003). This situation is not rare and several caprellid species have reached isolated islands in this way, such as the Ogasawara Islands located 1000 km south from the main Japan islands (Aoki & Asakura, 1995) and the Hawaiian Islands (McCain & Steinberg, 1970). Michel (1974) and Gherardi & McLaughlin s (1994) pointed out that the marine organisms of Mauritius consist mostly of species widespread in the Indo-Pacific. But their studies were mainly based on groups with pelagic larvae which are readily dispersed. For the gammarideans, even lacking the pelagic dispersal stage, Appadoo & Steele (1998) found similar distributions, with most species widely occurring in the Indo-Pacific. On the other hand, 57% of the gammarids reported from Mauritius are shared with Madagascar. A likely reason for the similarity between these two faunas is that Madagascar is the closest large land mass and organisms would have to move a relative short distance (800 km) to reach Mauritius; however, some amphipods likely reached Mauritius from distant places like India or other Indo-Pacific regions, their transport being influenced by ocean currents both present and past, and by their ability to survive adverse conditions while travelling long distances (Appadoo & Steele, 1998). In connection with the caprellids, in spite of the great number of samples collected during the present study, only seven species have been recorded in the present study, showing that the caprellid diversity on the island is not very high. The caprellid species found in Mauritius are cosmopolitan or widely distributed in the tropical Indo-Pacific following the same pattern as the gammaridean amphipods. In fact, the caprellid fauna from Mauritius, although considerable less rich in species, is rather similar to the fauna described from other coral-reef areas, such as the Great Barrier Reef of Australia (Guerra- García, personal observations). In fact, Berents (1983), after her study of the melitid gammarideans from tropical Australia, already pointed out the similarity between the amphipod fauna from Lizard Island at the Great Barrier Reef, and Mauritius. The moderately low caprellid species richness around Mauritius seems to follow a general pattern in the surrounding islands. Thus, Laubitz (1995) pointed out that the Réunion caprellid fauna, including only three species, is remarkably lean taking into consideration the wide range of collections which she studied. Apart from the present study, the work of Laubitz (1995) and the study of Guerra- García (2002d) there is a lack of recent work dealing with the caprellids from the Indian ZOOTAXA MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 21

22 Ocean (McCain & Steinberg, 1970). Further studies are necessary in this area to elucidate the caprellid diversity of the Indian Ocean. Acknowledgements The author is very grateful to the Albion Fisheries Research Centre, for the facilities provided during the study. Special thanks to the diving team : M.S. Koonjul, J.P. Luchmun, V. Mangar, K. Mungry and C. Samyam for assistance during sampling. Thanks are also due to H. Terashima (Japan International Cooperation Agency) for help and advice, and to Rishi, Mr. Nemchand and Y. Emamdi for hospitality and encouragement during the stay in Mauritius. This study was supported by a grant AP from the Ministry of Education, Culture and Sport from Spain. References Aoki, M. (1999) Morphological characteristics of young, maternal care behaviour and microhabitat use by caprellid amphipods. Journal of the Marine Biological Association of United Kingdom, 79, Aoki, M. & Asakura, A. (1995) Caprellids (Crustacea: Amphipoda: Caprellidae) collected from the Ogasawara (Bonin) Islands. Journal of Natural History of the Museum Chiba, 3, Appadoo, C. & Steele, D.H. (1998) Shallow-water marine gammaridean amphipods of Mauritius Island. Crustaceana, 71, Appadoo, C., Myers, A.A. & Fagoonee, I. (2002a) The genera Quadrimaera and Maera (Amphipoda: Gammaridea: Melitidae) from Mauritius. Journal of Natural History, 36, Appadoo, C., Myers, A.A. & Fagoonee, I. (2002b) The genus Mallacoota (Crustacea, Amphipoda, Melitidae) from Mauritius, with description of a new species. Journal of Natural History, 36, Arimoto, I. (1976) Taxonomic studies of caprellids (Crustacea, Amphipoda, Caprellidea) found in the Japanese and adjacent waters. Special Publications from the Seto Marine Biological Laboratory, 3, Barnard, J.L. (1976) Amphipoda (Crustacea) from the Indo-Pacific tropics: a review. Micronesia, 12, Berents, P.B. (1983) The Melitidae of Lizard Island and adjacent reefs, the Great Barrier Reef, Australia (Crustacea: Amphipoda). Records of the Australian Museum, 35, Dana, J.D. (1853). Crustacea. Part II. United States Exploring Expedition, 14, Gable, M. F. & Lazo-Wasem, E.A. (1987) The Caprellids (Amphipoda: Caprellida) of Bermuda: a survey of specimens collected from , including cave inhabitants, and the description of Deutella aspiducha, new species. Proceedings of the Biological Society of Washington, 100, Gherardi, F. & McLaughlin, P.A. (1994) Shallow-water hermit crabs (Crustacea: Decapoda: Anomura: Paguridea) from Mauritius and Rodrigues islands, with the description of a new species of Calcinus. Raffles Bulletin of Zoology, 42, Magnolia Press GUERRA-GARCÍA

23 Guerra-García, J.M. (2002a) Metaprotella tanzaniensis, a new caprellid (Crustacea: Amphipoda) from Tanzania, with a key to the species of Metaprotella and discussion on the family Protellidae. Bulletin of Marine Science, 70, Guerra-García, J.M. (2002b) Revision of the genus Noculacia Mayer, 1903 (Crustacea: Amphipoda: Caprellidea) with the description of two new species. Organisms, Diversity and Evolution, 2, Guerra-García, J.M. (2002c) Redescription of five rare caprellids (Crustacea: Amphipoda: Caprellidea) collected from Tanzanian coasts. Helgoland Marine Research, 55, Guerra-García, J.M. (2002d) Two new species of Deutella Mayer, 1890 (Crustacea: Amphipoda: Pariambidae) collected by the R. V. Anton Bruun during the International Indian Ocean Expedition Zootaxa, 74, Guerra-García, J.M. & Thiel, M. (2001) The caprellid fauna (Crustacea: Amphipoda: Caprellidea) from the coast of Coquimbo, Northern-central Chile, with a taxonomic key for species identification. Revista Chilena de Historia Natural, 74, Haswell, W.A. (1880) On some Amphipods from Australia and Tasmania. Proceedings of the Linnean Society of New South Wales, 5, Larsen, K. (1997) A new species of Metaprotella (Crustacea: Amphipoda: Caprellidea) from east Africa, with key to the genera of Protellidae and discussion of generic characters. Journal of Natural History, 31, Laubitz, D.R. (1972) The Caprellidae (Crustacea, Amphipoda) of Atlantic and Arctic Canada. National Museum of Natural Sciences Publications in Biological Oceanography, 4, Laubitz, D.R. (1995) Caprellidea (Crustacea: Amphipoda) from the Southern and Western Indian Ocean. Mésogée, 54, Ledoyer, M. (1978) Amphipodes gammariens (Crustacea) des biotopes cavitaires organogènes récifaux de l île Maurice (Océan Indien). Mauritius Institute Bulletin, 8, Lim, S.T.A. & Alexander, C.G. (1986) Reproductive behaviour of the caprellid amphipod Caprella scaura typica Mayer, Marine Behaviour and Physiology, 12, Mayer, P. (1890) Die Caprelliden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. Fauna und Flora des Golfes von Neapel, 17, Mayer, P. (1898) Metaprotella sandalensis n. sp. In: Willey, A (Ed) Zoological results based on material from New Britain, New Guinea, Loyalty Island and elsewhere, collected during the years 1895, 1896, and 1897, Cambridge, pp Mayer, P. (1903) Die Caprelliden der Siboga-Expedition. Siboga Expeditie, 34, McCain, J.C. (1968) The Caprellidae (Crustacea: Amphipoda) of the western North Atlantic. United States National Museum Bulletin, 278, McCain, J.C. & Steinberg, J.E. (1970) Amphipoda I, Caprellidea I, Family Caprellidae. In: Gruner, H.E, & Holthuis, L.B (Ed) Crustaceorum Catalogus, 2, Michel, C. (1964) Check list of the Crustacea Brachyura (crabs) recorded from Mauritius. Mauritius Institute Bulletin, 6, Müller, H.G. (1990) New species and records of coral reef inhabiting Caprellidae from Bora Bora and Moorea, Society Islands (Crustacea: Amphipoda). Revue Suisse de Zoologie, 97, Myers, A.A. (1993) Dispersal and endemicity in gammaridean Amphipoda. Journal of Natural History, 27, Myers, A.A. & Giller, P.S. (1988) Process, pattern and scale in biogeography. In: Myers, A. A.& Giller, P.S. (Ed) Analytical biogeography: an integrated approach to the study of animal and plant distributions, New York, pp Quitete, J.M.P.A. (1972) Hemiagina costai,novaespéciedecaprellidaedacostabrasileira(crustacea: Amphipoda). Atas da Sociedade de Biologia do Rio de Janeiro, 15, ZOOTAXA MAURITIUS ISLAND CAPRELLIDEA 2003 Magnolia Press 23

24 Schultz, M.K. & Alexander, C.G. (2001) Aggressive behaviour of Caprella scaura typica Mayer, 1890 (Crustacea: Amphipoda). Marine and Freshwater Behaviour and Physiology, 34, Serejo, C. (1997) Hemiaegina costai Quitete, 1972 a synonym of Hemiaegina minuta Mayer, 1890 (Amphipoda: Caprellidae). Crustaceana, 70, Sundara Raj, B. (1927) Suborder Caprellidea (Laemodipoda). The littoral fauna of Krusada Island in the Gulf of Manaar. The Bulletin of the Madras Government Museum. Natural History Section, 1, Takeuchi, I. & Hino, A. (1997) Community structure of caprellid Amphipoda (Crustacea) on seagrasses in Otsuchi Bay, northeastern Japan, with reference of the association of Caprella japonica (Schurin) and Phyllospadix iwatensis Makino. Fisheries Science, 63, Takeuchi, I. & Sawamoto, S. (1998) Distribution of caprellid amphipods (Crustacea) in the western North Pacific based on the CSK International Zooplankton Collection. Plankton Biology and Ecology, 45, Templeton, R. (1836) Description of some undescribed exotic Crustacea. Transaction of the Entomological Society of London, 1, Thiel, M., Guerra-García, J.M, Lancellotti, D.A. & Vásquez, N. (2003) The distribution of littoral caprellids (Crustacea: Amphipoda: Caprellidea) along the Pacific coast of continental Chile. Revista Chilena de Historia Natural, 76, Utinomi, H. (1947) Caprellidea of Japan and adjacent waters. Seibutu Supplement, 1, Magnolia Press GUERRA-GARCÍA