Caprellids (Crustacea: Amphipoda) from India

ORIGINAL ARTICLE Caprellids (Crustacea: Amphipoda) from India J. M. Guerra-Garcı ´a•T. Ganesh •M. Jaikumar • A. V. Raman Received: 24 July 2009 / Revised: 18 November 2009 / Accepted: 20 November 2009 / Published online: 9 December 2009 ÓSpringer-Verlag and AWI 2009 Abstract The caprellid fauna of India is investigated. A total of 538 samples (including algae, seagrasses, sponges, hydroids, ascidians, bryozoans, encrusted dead corals, coral rubble, fine and coarse sediments) were collected from 39 stations along the coast of India, covering a wide diversity of habitats from intertidal to 12 m water depth. A new species (Jigurru longimanus n.sp.) is described, and figures of the 11 valid species reported so far from India are given together with a key for their identification. No caprellids were found in sediments from the northeast (16–208N) coast of India while they were abundant in the southeast and west coast. Decreases in salinity due to river discharges associated with lower values of oxygen, higher water temperatures and lower nutrient inputs along the east coast could explain these differences in caprellid composition between the two coastlines. Significantly, lower abundance of caprellids in India, as in other tropical ecosystems, is probably related to the lack of species belonging to the genus Caprella, which reach very high abundances in temperate waters. Keywords Amphipoda Caprellidea New species  India Introduction In general, there is a lack of studies dealing with the Caprellidea from the Indian Ocean and Indo-Pacific region (McCain and Steinberg 1970). Nevertheless, there is an increasing attempt to improve the knowledge of the Indo-Pacific caprellids, and recent contributions have been published dealing with the Caprellidea from Thailand (Takeuchi and Guerra-Garcı ´a2002; Guerra-Garcı ´a2004a), Indonesia (Krapp-Schickel and Guerra-Garcı ´a2005), Philippines (Guerra-Garcı ´a2002a), Hong Kong (Guerra-Garcı ´a and Takeuchi 2003), Papua New Guinea (Guerra-Garcı ´a 2003a), northwestern Australia (Guerra-Garcı ´a2004b), Tanzania and east coast of Africa (Guerra-Garcı ´a2001, 2002b,c,d) and Mauritius Island (Guerra-Garcı ´a2003b). The Caprellidae from India had received only marginal attention in the past. Giles (1888) in his notes on the Amphipoda of Indian waters described two caprellid species for India: Caprella madrasana Giles 1888, collected from 11 to 16.4 m, off Madras and Palk’s Straits, and Caprella palkii Giles 1888, collected from 12.8 m off Palk’s Straits. Sivaprakasam (1977) reported that these two species were not recognizable because of poor descriptions and illustrations. In fact, type material of these two species, housed in the Natural History Museum, London, is in a very poor condition, but they seem not to be valid species: Caprella madrasana have tiny pereopods 3 and 4 and probably belongs to the genus Paracaprella, and Caprella palki is originally belonging to the genus Metaprotella. After the study of Giles (1888), Mayer (1890) described three new species from Pamban Bridge, Gulf of Mannar: Metaprotella excentrica Mayer 1890,Metaprotella problematica Mayer 1890 and Paradeutella bidentata Mayer 1890, and recorded also Hemiaegina minuta Mayer 1890 from Krusadai Island and Metaprotella haswelliana Communicated by H.-D. Franke. J. M. Guerra-Garcı ´a(&) Laboratorio de Biologı ´a Marina, Departamento de Fisiologı ´a y Zoologı ´a, Facultad de Biologı ´a, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain e-mail: [email protected] T. Ganesh M. Jaikumar A. V. Raman Marine Biological Laboratory, Department of Zoology, Andhra University, Visakhapatnam 530003, India 123 Helgol Mar Res (2010) 64:297–310 DOI 10.1007/s10152-009-0183-6 f. taprobanica Mayer 1890 from Pambam Bridge. Recently, Takeuchi and Lowry (2007) redescribed Metaprotella haswelliana based on material from Western Australia and indicated that M. haswelliana f. taprobanica is probably a different species from M. haswelliana from Western Australia. However, these authors pointed out that in view of the small size of the specimen, probably juvenile, redescription of M. haswelliana f. taprobanica should await availability of larger and mature specimens. Mayer (1904) reported four valid species from Sri Lanka (M. excentrica, M. problematica,Paradeutella bidentata and Monoliropus falcimanus Mayer 1904). Sundara Raj (1927) listed five species from Pamban: M. problematica,P. bidentatata, Hemiaegina quadripunctata (=H. minuta), Metaprotella haswelliana (Mayer 1882) and Pseudocaprellina pambanensis Sundara Raj 1927. T. E. Sivaprakasam has been the most important contributor to the knowledge of the Caprellidea of India; Sivaprakasam (1969,1970) reported four species from the Madras coast: M. falcimanus,P. bidentata,Paracaprella alata Mayer, 1903 and P. barnardi McCain 1967. Sivaprakasam (1977) represents the best review so far of the Caprellidea from India, reporting nine species of caprellids collected from the Tamil Nadu and Kerala Coasts: P. pambanensis,M. excentrica,M. problematica,M. falcimanus,P. bidentata,H. minuta,P. alata, P. barnardi and P. pusilla Mayer 1890. According to the figures of Sivaprakasam (1977) and the original descriptions of McCain (1967), specimens identified as P. barnardi by this author are originally belonging to P. pusilla. Recently, Swarupa and Radhakrishna (1983) described the species Heterocaprella krishnaensis collected from the Tamil Nadu and Kerala Coasts. Thus, only 10 valid species of caprellids are so far known from Indian waters, viz. Hemiaegina minuta,Heterocaprella krishnaensis,Metaprotella excentrica,M. haswelliana f. taprobanica,M. problematica,Monoliropus falcimanus,Paracaprella alata,P. pusilla,Paradeutella bidentata and Pseudocaprellina pambanensis. The present study adds the eleventh, Jigurru longimanus n.sp. During December 2004 and January 2005, the authors conducted a sampling programme targeting caprellids of India, mainly from the East and South coasts. The material contained four species, including Jigurru longimanus which is new to science. Materials and methods Samples were collected from 39 stations along the Indian coasts (see Station List and Fig. 1), covering a wide diversity of habitats from the intertidal to 12 m depth. A total of 538 samples of potential substrates for the Caprellidae were collected, including algae, seagrasses, sponges, hydroids, ascidians, bryozoans, encrusted dead corals, coral rubble, fine and coarse sediments. The most abundant algae during the study were Caulerpa taxifolia,Caulerpa racemosa,Cladophora spp., Amphiroa spp., Chaetomorpha spp., Gracilaria spp., Gigartina spp., Halarachnion spp., Padina spp. and Sargassum spp. The sediment samples were collected by using a van Veen grab (mouth area: Fig. 1 Study area showing the sampling localities (see station list in the ‘‘material and methods’’ section). Filled circles, caprellids present; open circles, caprellids absent 298 Helgol Mar Res (2010) 64:297–310 123 0.03 m 2 ) or manually by dragging fine nylon mesh bags along the bottom. The remaining substrates were collected directly from the intertidal or by snorkelling in shallow waters, and the samples were transferred to labelled polythene bags. The samples were fixed in formalin 4% and then transferred to 70% ethanol. Selected specimens were dissected under a Leica dissecting microscope. Appendages of selected specimens were mounted in polyvinyl lactophenol, and camera lucida drawings were made using a Leica compound microscope. Although the phylogeny and higher classification of the caprellids are still under debate (see Laubitz 1993; Takeuchi 1993; Ito et al. 2008), Myers and Lowry (2003) have recently proposed a new phylogeny and classification for the suborder Corophiidea Leach, 1814. Based on hypothesis of the evolution of different feeding strategies, the Corophiidea is divided into two infraorders, the Corophiida and the Caprellida. In their new classification, the superfamily Caprelloidea contains five families: Caprellidae, Caprogammaridae, Cyamidae, Dulichiidae and Podoceridae. The Caprellidae are subdivided into three subfamilies: Caprellinae, Paracercopinae and Phtisicinae. In the present paper, we have adopted the classification of Myers and Lowry (2003) and have focused our study on members of the family Caprellidae. The symbols used in the present work are: A1,2 = Antenna 1,2; UL =Upper lip; LL =Lower lip; LMd =Left mandible; RMd =Right mandible; Mx1,2 =Maxilla 1,2; Mxp =Maxilliped; Gn1,2 =Gnathopod 1,2; P5–7 = Pereopods 5–7; Ab =Abdomen; MNCN =Museo Nacional de Ciencias Naturales, Madrid, Spain; LBM =Laboratorio de Biologı ´a Marina, Sevilla, Spain. Only an abbreviated list of synonyms is given under each species, since an extensive synonymy is given by McCain and Steinberg (1970). Station list Station 1 Diamond harbour beach. Intertidal, sediments (silt and clay). 21 February 2005 (5 samples). No caprellids. Station 2 Diamond harbour. Fishing harbour. Intertidal, seaweeds. 21 February 2005 (3 samples). No caprellids. Station 3 Chilika lagoon. Sediments (some areas with the seagrass Halophila sp.), 0.3–2 m depth, brackish waters with salinity between 0.55 and 15 psu. September 2004 (54 samples). No caprellids. Station 4 Rushikonda Beach. Intertidal rocky shore, seaweeds (Sargassum sp., Padina pavonica among others). 31 January 2005 (12 samples). No caprellids. Station 5 Jodugulapalem. Intertidal rocky shore, seaweeds (Gigartina sp.,Fauchea sp. among others). 23 January 2005 (8 samples). No caprellids. Station 6 Tenneti Park. Intertidal rocky shore, seaweeds (Caulerpa taxifolia,Caulerpa racemosa,Cladophora sp., Chaetomorpha sp., Gracilaria sp. and others). 23 January 2005 (10 samples). No caprellids. Station 7 Appu Ghar. Intertidal rocky shore, seaweeds (Enteromorpha spp., Amphiroa spp., and others). 23 January 2005 (5 samples). No caprellids. Station 8 Vuda Beach (17843.40N, 83820.60E). Intertidal rocky shores, seaweeds (Amphiroa sp., Caulerpa cf racemosa,Ceramium spp. among others), sponges, tiny hydroids, substrates under boulders. T a 25–27°C. 14 January 2005 (13 samples). Abundant epiphytic fauna (gammarids, isopods, decapods, tanaids, etc.) but no caprellids. Station 9 Palm Beach. Intertidal rocky shores, seaweeds (Sargassum sp.,Laurencia spp.,Amphiroa spp., Cladophora spp. among others), sediments 1 m depth, substrates under boulders. 15, 24–25 January 2005 (25 samples). Abundant epiphytic fauna (gammarids, isopods, decapods, tanaids, etc.) but no caprellids. Station 10 Ramakrishna Beach. Intertidal rocky shores, seaweeds. 16 January 2005 (5 samples). No caprellids. Station 11 Fishing harbour. Intertidal turf algae, very polluted area. 18 January 2005 (3 samples). No caprellids. Station 12 Outer harbour. Intertidal seaweeds. 18 January 2005 (3 samples). No caprellids. Station 13 Harbour. Fouling communities on boats (turf algae, tiny hydroids). 28 January 2005 (5 samples). Paracaprella pusilla (42 specimens). Station 14 Dolphin’s Nose. Intertidal seaweeds. 26 January 2005 (10 samples). No caprellids. Station 15 Kakinada. Mangrove creeks, 1.5 m depth. 1996 (4 samples). No caprellids. Station 16 Chennai. Fishing harbour (1387.590N, 80817.850E). Fouling communities on boats (turf algae, tiny hydroids). Salinity 33 psu. 3 February 2005 (15 samples). Paracaprella pusilla (10 specimens). Station 17 Marine Beach (1383.990N, 80817.360E). Intertidal rocky shore, seaweeds. Salinity 32 psu. 3 February 2005 (5 samples). No caprellids. Station 18 Mamallapuram (12836.940N, 80811.970E). Intertidal rocky shores, seaweeds. Salinity 29–30 psu. 11 February 2005 (15 samples). No caprellids. Helgol Mar Res (2010) 64:297–310 299 123 Station 19 Thondi Beach (9844.220N, 79801.080E). Fouling communities on boats (turf algae, tiny hydroids). Seaweeds from ropes (Gelidium spp and Gracilaria spp). Sediments and seagrass Thalassia sp., 2–3 m depth. Salinity 25 psu. 4 February 2005 (21 samples). No caprellids. Station 20 Fishing harbour (9842.700N, 78859.810E). Fouling communities (seaweeds, sponges, hydroids), 1– 2 m depth, snorkelling. Salinity 27 psu. 4 February 2005 (5 samples). Abundant epiphytic fauna (gammarids, isopods, decapods, tanaids, etc.), but no caprellids. Station 21 Khooni Tharai (9816.890N, 79811.080E). Seaweeds (Sargassum sp., Padina pavonica), seagrass (Thalassia sp.), hydroids from 1 to 4 m depth, substrates under boulders, sediments (0–2 m depth) collected by hand using mesh bags and a plankton net that was dragged along the bottom after digging up the bottom. Salinity 27–28 psu. 5 February 2005 (45 samples). No caprellids. Station 22 Near Pamban Bridge (9815.450N, 79812.420E). Fouling communities on buoys. Salinity 27–28 psu. 5 February 2005 (5 samples). No caprellids. Station 23 Kurusadai Island (9814.750N, 79813.130E). Seaweeds (Turbinaria among others) and sediments (0– 3 m depth) collected by hand using mesh bags and a plankton net that was dragged along the bottom after digging up. Salinity 28–29 psu. 5 February 2005 (20 samples). Metaprotella excentrica (1 specimen). Station 24 Down of Pamban Bridge (9816.950N, 79811.450E). Seaweeds (Halimeda,Gelidium,Caulerpa), sediments and substrates (hydroids and sponges) under boulders. Salinity 27 psu. 5 February 2005 (55 samples). No caprellids. Station 25 Vellapatti (8851.930N, 78811.550E–8852.130N, 78812.290E). Muddy sediments with Thalassia and Halophila, 2.5–4 m depth collected with van Veen grab. Salinity 31 psu. 10 February 2005 (10 samples). Metaprotella excentrica (8 specimens), Jigurru longimanus n.sp. (9 specimens). Station 26 Kasivari Island (8852.350N, 78813.480E). Sandy sediments with Halophila, coral rubble washed 1–2 m depth collected with van Veen grab and snorkelling. Salinity 31 psu. 10 February 2005 (8 samples). Metaprotella excentrica (14 specimens), Hemiaegina minuta (1 specimen). Station 27 Vann Island (8850.090N, 78812.230E). Coral rubble, 1–3 m depth, snorkelling. Salinity 31 psu. 10 February 2005 (10 samples). Paracaprella pusilla (7 specimens), Hemiaegina minuta (1 specimen). Station 28 Near Sugandhi Devadason Marine Research Institute (8844.950N, 78811.320E). Seaweed culture of Gracilaria, abundant bryozoans (Bugula neritina), 0–3 m depth, snorkelling. Salinity 32–33 psu. 6 February 2005 (16 samples). Paracaprella pusilla (202 specimens). Station 29 Fishing harbour (8847.560N, 78809.650E). Fouling communities. Salinity 29 psu. 6 February 2005 (7 samples). No caprellids. Station 30 Near harbour (8844.850N, 78811.540E). Sponges, sediments with Halophila. Salinity 35 psu. 6 February 2005 (7 samples). Metaprotella excentrica (1 specimen). Station 31 Kanniyakumari (8805.110N, 77833.180E). Intertidal rocky shore with high diversity and biomass of seaweeds (Ulva,Ceramium,Gracilaria,Caulerpa, Corallinacea). Salinity 34 psu. 9 February 2005 (12 samples). No caprellids. Station 32 Fishing harbour (8805.8310N, 77833.840E). Fouling communities on boats. Salinity 34 psu. 9 February 2005 (8 samples). Paracaprella pusilla (1 specimen). Station 33 Kollam Beach (8852.130N, 76835.170E). Sediments collected with van Veen grab, 2–12 m depth. Salinity 32 psu. 8 February 2005 (20 samples). No caprellids. Station 34 Neendakarai, outer harbour (8856.110N, 76832.240E). Intertidal rocky shore, seaweeds and hydroids. Salinity 26 psu. 8 February 2005 (13 samples). Paracaprella pusilla (19 specimens). Station 35 Fishing harbour (8856.210N, 76832.290E). Seaweeds and hydroids. Salinity 26 psu. 8 February 2005 (4 samples). No caprellids. Station 36 Elephanta Island. Intertidal, polluted. 27 February 2005 (5 samples). No caprellids. Station 37 Near Gateway of India. Fouling communities, polluted. 26 February 2005 (10 samples). No caprellids. Station 38 Chowpatty Beach. Fouling communities on boats and docks (turf algae, ascidians, hydroids). 25 February 2005 (17 samples). Paracaprella pusilla (4 specimens). Station 39 Juhu Beach. Intertidal, seaweeds, sediments, under boulders. 26 February 2005 (3 samples). No caprellids. Results List of species collected during the present study: Family Caprellidae Leach, 1814 Subfamily Phtisicinae Vassilenko, 1968 Jigurru longimanus n.sp. Subfamily Caprellinae Leach, 1814 Hemiaegina minuta Mayer 1890 300 Helgol Mar Res (2010) 64:297–310 123 Metaprotella excentrica Mayer 1890 Paracaprella pusilla Mayer 1890 Systematic account Subfamily Phtisicinae Vassilenko, 1968 Jigurru longimanus n. sp. (Figs. 2,3,4,5) Type material Holotype male, sta. 25 (MNCN 20.04/ 8221). Allotype female (MNCN 20.04/8222) and paratypes (2 males, 1 female, 2 juveniles MNCN 20.04/8223 ?1 male, 1 female, LBM) collected together with holotype. Type locality Sta. 25. Vellapatti (8851.930N, 78811.550E– 8852.130N, 78812.290E), near Tuticorin, India. Muddy sediments with Thalassia and Halophila, 2.5–4 m depth collected with van Veen grab. Salinity 31 psu. 10 February 2005 (10 samples). Etymology The specific name refers to the long basis and carpus of male gnathopod 2. Type species of the genus Jigurru vailhoggett Guerra- Garcı ´a2006 Diagnosis Antenna 2 flagellum two-articulate. Gills present on pereonites 2–4, following the size gill 3 [gill 4[gill 2. Basis and carpus of male gnathopod 2 significantly elongated. Pereopods 3 and 4 absent. Pereopod 5 three-articulate, with basal article almost divided at midlength. Pereopods 6 and 7 six-articulate. Mandibular palp three-articulate; distal article with two setae. Molar absent. Abdomen with two pairs of appendages. Gender: Masculine. Description: Holotype male (MNCN 20.04/8221) Body length. 4.2 mm. Lateral view (Fig. 2) Body smooth without projections; head rounded and elongate; suture between head and pereonite 1 absent. Gills (Fig. 2) Present on pereonites 2–4, rounded. Gills on pereonite 4 always smaller than those on pereonite 3. The first pair (on pereonite 2) the shortest. Mouthparts (Fig. 3) Upper lip symmetrically bilobed, small setae apically. Mandibles without molar; left Fig. 2 Jigurru longimanus n.sp. Lateral view of holotype male, allotype female and paratype juvenile. Scale bar:1mm Fig. 3 Jigurru longimanus n.sp. Mouthparts of holotype male. Scale bar: 0.1 mm Helgol Mar Res (2010) 64:297–310 301 123 mandible with incisor 5-toothed, lacinia mobilis 5-toothed followed by a row of plates decreasing in size; right mandible with incisor 5-toothed, lacinia mobilis like a plate, followed by row of plates; palp three-articulate, second article with one or two setae, distal article two apical setae and small setulae. Lower lip without setae; inner lobes poorly demarcated. Maxilla 1 outer lobe with six robust and stout setae; distal article of palp with three setae and three teeth distally and a row of three lateral setae. Maxilla 2 inner lobe rectangular with four setae; outer lobe rectangular with four setae. Maxilliped inner plate with a serrate margin and three apically serrate nodular setae; outer plate with three simple setae; palp four-articulate, article 2 laterally expanded, with four setae; article 3 with distal triangular projection. Antennae (Figs. 2,4) Antenna 1 about 1/3 of the body length; flagellum three-articulate. Antenna 2 a little shorter than the half of the antenna 1, non-setose; flagellum twoarticulate. Gnathopods (Figs. 2,4) Gnathopod 1 basis as long as ischium, merus and carpus combined; propodus triangular, length about 1.5 times width, palm with three proximal grasping spines, grasping margin minutely denticulate on anterior half; dactylus elongate. Gnathopod 2 inserted on the posterior part of pereonite 2; basis twice as long as pereonite 2; ischium rectangular; merus rounded; carpus very elongate, almost as long as the basis; propodus elongate, length about four times width, palm with a proximal grasping spine; dactylus curved on the distal half. Pereopods (Fig. 5) Pereopods 3 and 4 absent. Pereopod 5 three-articulate, but basal article almost divided into two articles. Pereopods 6 and 7 lacking in the holotype male, described from the juvenile: six-articulate, ischium and merus with one seta, carpus with three (pereopod 6) or four (pereopod 7) spines along the palm, carpus with three spines, dactylus smooth. Penes (Fig. 5) small, located centrally. Abdomen with two pair of appendages; first pair of appendages twoarticulate; second pair uniarticulate. Allotype female (MNCN 20.04/8222) Body length 2.7 mm. Oostegites (Fig. 2) without setae. Gnathopod 2 (Figs. 2,4) inserted on the anterior half of pereonite 2; basis as long as pereonite 2; carpus triangular; propodus oval, length about twice width; three grasping spines proximally Remarks The genus Jigurru shares some characters with Caprellina Nicolet, 1849 and Prellicana Mayer, 1903. Jigurru appears to be closer to Caprellina than Prellicana on the basis of the presence of three pairs of gills, reduced pereonite 5 and two pairs of appendages in the abdomen. Nevertheless, the small size, general features of the body, the incomplete articulation of the basal article in the pereopod 5, the shape of pereopods 6 and 7, and the Fig. 4 Jigurru longimanus n.sp. Male holotype antenna 1 (detail of flagellum), antenna 2 and gnathopods 1 and 2 (only propodus and dactylus represented). Female allotype gnathopod 2. Scale bars:0.1 mm Fig. 5 Jigurru longimanus n.sp. Male holotype pereopod 5 in scale x=0.05 mm; Paratype juvenile pereopods 6 and 7 in scale y=0.1 mm; male holotype and female allotype abdomen in scale z=0.05 mm 302 Helgol Mar Res (2010) 64:297–310 123 partially fused inner plates of the maxilliped strongly resemble Prellicana.Prellicana, however, has only two pairs of gills and one pair of abdominal appendages, whereas Jigurru possesses three pairs of gills and two pairs of abdominal appendages. The genus Jigurru includes two species, Jigurru vailhoggett, described from Lizard Island, Great Barrier Reef (see Guerra-Garcı ´a2006) and the new species Jigurru longimanus. Both species are morphologically very similar, but can be distinguished by the combination of the following characters: (1) Carpus of adult male gnathopod 2 longer than basis in J. longimanus and shorter in J. vailhoggett, (2) gills elongate in J. vailhoggett (and similar in size) and round in J. longimanus (gill3 [- gill4 [gill2), (3) projection of article 3 of maxilliped palp rectangular and serrated distally in J. vailhoggett, and triangular without serrated margin in J. longimanus, (4) distal article of mandibular palp with three long setae in J. vailhoggett, and two distal setae and row of tiny setulae in J. longimanus, 5) penes larger in J. vailhoggett (situated laterally), and shorter in J. longimanus (situated medially) Habitat So far, the species has only been found in muddy sediments with Thalassia and Halophila. Distribution So far, found only in the type locality. Subfamily Caprellinae Leach,1814 Hemiaegina minuta Mayer 1890 (Fig. 6) Hemiaegina minuta Mayer 1890: 40, pl. 1, figs. 25–27, pl. 3, figs. 32–35, pl. 5, figs. 52–53, pl. 6, figs. 13, 33–34, pl. 7, fig. 4; McCain 1968: 61–64, figs. 29–30; McCain and Steinberg 1970:51; Gable and Lazo-Wasem 1987: 637; Mu ¨ller 1990: 836; Serejo 1997: 630–632, fig. 1; Guerra- Garcı ´a2003a: 105–106, fig. 10; Guerra-Garcı ´a2003b: 6–7, fig. 3; Guerra-Garcı ´a, 2004: 39–40, fig. 32; Dı ´az et al. 2005: 5–6, fig. 9; Krapp-Schickel and Guerra-Garcı ´a2005: 50–51, fig. 3; Guerra-Garcı ´a2006: 443, fig. 43. Hemiaegina quadripunctata Sundara Raj 1927: 126– 127, pl. 18. Hemiaegina costai Quitete 1972: 165–168, pls. 1–2. Material examined 1 female sta. 26, 1 juvenile sta. 27 (used for lateral view figures). Remarks The material of H. minuta found during the present study could be identified as Hemiaegina minuta since this species shows very distinctive and clear diagnostic characteristics, which facilitate the identification: third article of antenna 1 short; antenna 2 without swimming setae; gnathopod 1 propodus with a round projection proximally; gnathopod 2 basis elongate and longer than pereonite 2, and propodus large, with a proximal grasping spine and distal U-notch and projection; pereopods 3 and 4 rounded and small, one-articulated; gills elongate; abdomen provided with a very distinctive pair of two-articulate appendages. Habitat Hemiaegina minuta has been collected from Sargassum sp. and taken in plankton tows (McCain and Steinberg 1970). Mu ¨ller (1990) reported H. minuta preferring more or less exposed reef locations. The species has also been collected from Thalassia testudinium (Stoner and Lewis 1985). Guerra-Garcı ´a(2003b) found the species associated with Turbinaria ornata (Turner) J. Agardh on Mauritius coast, and Guerra-Garcı ´a(2003a) reported H. minuta from Papua New Guinea living on Dictyota sp., Halimeda sp., Gracilaria sp., Galaxaura sp. and Amansia glomerata (Agardh) Norris, 1979. This species has also been found associated with many different substrata in Australia: green algae such as Halimeda sp., brown and red algae, sponges, tunicates, seagrasses such as Posidonia sp., dead corals encrusted with algal turf, and under small boulders (Guerra-Garcı ´a 2004). In Venezuela, the species has been found on turkey wings (Arca zebra) (Dı ´az et al. 2005), and Krapp-Schickel and Guerra-Garcı ´a(2005) found the species living in algae from shallow waters. Fig. 6 Hemiaegina minuta. Lateral view of female and juvenile male. Scale bar:1mm Helgol Mar Res (2010) 64:297–310 303 123 During the present study, the species was collected in sediments with Halophila, and among coral rubble. Distribution Type locality: Off Amoy, China, 15–46 m. depth (McCain 1968). Other records: west coast of United States, Venezuela South Africa, Hawaii, Bora Bora, Japan, Papua New Guinea, Australia, India, Mauritius, South Arabian coast, Indonesia (McCain and Steinberg 1970; Guerra-Garcı ´a2003a, 2004; Dı ´az et al. 2005; Krapp- Schickel and Guerra-Garcı ´a2005; Guerra-Garcı ´a2006). Hemiaegina minuta is widely distributed in tropical and temperate waters of the world oceans (McCain 1968). Metaprotella excentrica Mayer 1890 (Fig. 7) Metaprotella excentrica Mayer 1890: 25–26, pl. 1, figs. 20–21; pl. 3; figs. 30–31; pl. 5, fig. 22; Mayer, 1903: 40; Mayer 1904: 224–225; Sundara Raj 1927: 126; Sivaprakasam 1977: 81–84, figs. 3–4. Material examined Sta. 23: 1 juvenile; Sta. 25: 2 males, 2 females, 4 juveniles; Sta. 26: 3 males, 7 females, 4 juveniles (1 male and 1 female from this station used for lateral view figures); Sta. 30: 1 juvenile. Remarks The present material agrees with the original description of Mayer (1890) based on material collected from Pamban Bridge, India (type locality), and with the descriptions and figures of Sivaprakasam (1977). This species can be easily distinguished from the remaining species of Metaprotella by the arrangement of dorsal projections and by the presence of triangular projections on the basis of male gnathopod 2. Habitat The species is usually found clinging on algae (Sivaprakasam 1977). During the present study, M. excentrica was collected from seaweeds like Turbinaria, sediments with Thalassia and Halophila, coral rubble and sponges. Distribution Type locality: Pamban Bridge, India. Other records: Sri Lanka and Australia (McCain and Steinberg 1970) (Fig. 8). Paracaprella pusilla Mayer 1890 (Fig. 8) Paracaprella pusilla Mayer 1890: 41, pl. 1, figs. 28–30; pl. 3; figs. 45–47; pl. 5, figs. 48–49; pl. 6, fig. 10; 1903: 67, pl. Fig. 7 Metaprotella excentrica. Lateral view of male and female. Scale bar:1mm Fig. 8 Paracaprella pusilla. Lateral view of male and female. Scale bar:1mm 304 Helgol Mar Res (2010) 64:297–310 123 2, figs. 36–37; pl. 7, fig. 52; Steinberg and Dougherty 1957: 283–284, figs. 16, 19, 24, 30; McCain 1968: 82–86, figs. 41–42; Wakabara et al. 1991: 73; Camp, 1998: 132; Guerra-Garcı ´a and Thiel 2001: 880, fig. 8; Dı ´az et al. 2005: 6–7, 22, fig. 13; Guerra-Garcı ´a et al. 2006: 175–178, figs. 17–19. Caprella nigra Reid 1951: 283–284, 289, fig. 58. Material examined Sta. 13: 22 males, 18 females, 2 juveniles; Sta. 16: 8 males, 2 females; Sta. 27: 2 males, 1 female, 4 juveniles; Sta. 28: 79 males, 77 females, 46 juveniles (1 male and 1 female from this station used for lateral view figures); Sta. 32: 1 female; Sta. 34: 8 males, 11 females; Sta. 38: 1 male, 3 juveniles. Remarks Mayer (1890) described Paracaprella pusilla based on material collected from Brazil. Later, this species was reported from Venezuela by McCain (1968). Paracaprella pusilla is similar to Paracaprella tenuis Mayer, 1903; however, males of P. pusilla can be distinguished from those of P. tenuis by the large sharp-pointed projection on the anteroventral margin of pereonite 2, the proximal knob on the basis of gnathopod 2 and the presence of setae on the dactylus of gnathopod 2 (McCain 1968). Large males of P. pusilla are very similar to large males of Paracaprella barnardi McCain 1967, in that they both bear a small anterodorsal tubercle on pereonite 2; however, the tubercle is not as well developed in the former as in the later, and the ventrolateral projection on the anterior margin of pereonite 2 is much larger in P. pusilla (McCain 1967). Sivaprakasam (1977) reported the species Paracaprella alata,P. barnardi and P. pusilla for Indian coasts. He found only a female of P. pusilla from Kerala and several hundred specimens of P. barnardi from hydroid colonies of Tamil Nadu, Kerala and Pondicherry. However, Sivaprakasam’s figures of Paracaprella barnardi (see Fig. 10, Sivaprakasam 1977) show that the specimens figured do not belong to P. barnardi; indeed, they probably belong to P. pusilla by the shape and size of ventrolateral projection of pereonite 2, the shape of gnathopod 2 and the small size of the anterodorsal tubercle on pereonite 2. On the other hand, the ‘‘abnormal male’’ described by Sivaprakasam (1977) with the large tooth on palmar notch could even belong to the species Paracaprella digitimanus (see Dı ´az et al. 2005). Habitat Paracaprella pusilla has been collected from mangrove roots, seagrasses, hydroids and ascidians (McCain 1968) and also from gravel bottoms, ropes, mussels, oysters, sabellariid worm rock [Phragmatopoma lapidosa (Kinberg, 1867)] and hydroids (such as Halocordyle disticha) associated with mangrove roots (Dı ´az et al. 2005). During the present study, the species was mainly not only found associated with fouling communities in harbours (on hydroids, ascidians and turf algae), but also inhabiting hydroids from intertidal rocks and clinging to bryozoans associated with Gracilaria cultures. It was the most abundant caprellid found during the present work. Distribution Type locality: Rio de Janeiro, Brazil. Other records: Western North Atlantic, Tropical West Africa and South Africa, Tanzania, Suez Canal, Hawaii, China, Gulf of Mexico, Venezuela, Cuba, Colombia (McCain and Steinberg 1970; Wakabara et al. 1991; Ortı ´z and Lalana 1998;Dı ´az et al. 2005; Winfield et al. 2006). Key to the caprellids from India (based on adult male specimens; see also Fig. 9). This key has been prepared trying to select the easiest external characters to be used without need of dissection. 1. Large ventral projection on pereonite 4 Heterocaprella krishnaensis Pereonite 4 without projection 2 2. Body with dorsal projections 3 Body without dorsal projections 5 3. Dorsal projections present on pereonite 3 Metaprotella excentrica Dorsal projections absent on pereonite 3 4 4. Two dorsal projections on pereonite 2. Pereopods 3 and 4 longer than half of gills Metaprotella haswelliana f. taprobanica A single dorsal projection on pereonite 2. Pereopods 3 and 4 shorter than half of gills Paradeutella bidentata 5. Gills present on pereonites 2, 3 and 4 6 Gills present on pereonites 3 and 4 7 6. Gnathopod 2 very elongate, as long as the half of the body Jigurru longimanus Gnathopod 2 clearly shorter than half of the body Pseudocaprellina pambanensis 7. Lateral expansions on pereonites 8 Pereonites without lateral expansions 9 8. Lateral expansions on pereonites 2–6, antennae 1 longer than half of the body Metaprotella problematica Lateral expansions on pereonite 3 and 4, antennae 1 shorter than half of the body Paracaprella alata 9. Pereonite 2 without anterolateral projection Hemiaegina minuta Anterolateral projection present on pereonite 2 10 10. Antennae 1 peduncle provided with small setae. Gills rounded. Basis of gnathopod 2 with a proximal knob Paracaprella pusilla Antennae 1 peduncle non-setose. Gills elongate. Basis of gnathopod 2 without proximal knob Monoliropus falcimanus Helgol Mar Res (2010) 64:297–310 305 123