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Caprella mendax Mayer, 1903 (Figures 6–8) Caprella mendax Mayer 1903; Laubitz 1970. Caprella equilibra: Dougherty and Steinberg 1953. Material examined St1: 67 males, 56 females, 54 juveniles; St2: 11 males, 5 females, 6 juveniles; St4: 6 males. Remarks Typical features of the species are present such as body smooth, a small projection at the base of each gnathopod 2 or length of pereonite 5 larger than pereonite 4. Mouthparts typical of genus. Antenna 1 longer than pereonites 1, 2 and 3 with 16 articles in flagellum. Gnathopod 2 inserted posteriorly on pereonite 2; basis shorter than half pereonite 2 and one-quarter of total appendage length, with an anterior denticulate carina; propodus twice as long as broad, palm with one proximal grasping spine, and poison tooth and triangular projection distally. Pereopods 5, 6 and 7 increasing in length, with propodus with proximal grasping spines and concave palm. Abdomen typical of genus. However, our specimens showed characteristics of both Caprella mendax and C. equilibra (Table 2), although, according to Mayer (1903) and Laubitz (1970), because the main differences are based on the structure of the second gnathopod and the length of pereonite 5 being greater than pereonite 4 in the first species, we have tentatively assigned them to C. mendax. Laubitz (1970) found specimens up to 16.4 and 11.2 mm in length for males and females, respectively, but the largest male and female lengths in our study were 9.3 and 7 mm. One of the more distinctive features in both C. mendax and C. equilibra is the presence of a ventral acute projection between gnathopods 2, which is absent in the material studied. McCain (1968) reported a variant of C. equilibra, associated with the gorgonian Leptogorgia, along the coast of Virginia, North Carolina and South Carolina in which the spine was reduced or absent and the body not quite as stout as in the typical form. Our material was also found on gorgonians (Leptogorgia rigida, Leptogorgia peruviana, Muricea sp. and Pacifigorgia sp.). In agreement with McCain (1968), this substrate may have some relation to the reduction of the spine and stoutness of the body. Further studies would be necessary to clarify this question and to elucidate the potential synonymy between C. equilibra and C. mendax. Habitat Caprella mendax occurs predominately in the intertidal zone and shallow waters (Watling and Carlton 2007), although it has also been found up to 80 m deep (Martin 1977). It lives on a great variety of substrates such as seaweeds (Hammer and Zimmerman 1979) or hydroids (Dougherty and Steinberg 1953). In our study, C. mendax was more abundant in shallow waters (up to 5 m) on seaweeds (Zonaria cf. farlowii) with epiphytic hydroids and on gorgonians (Leptogorgia rigida, Leptogorgia peruviana, Muricea sp. and Pacifigorgia sp.). Distribution Type locality. California. Other records: Dillon Beach, Moss Beach and Pacific Grove-Monterey Bay, California (Dougherty and Steinberg 1953); Vancouver Island and Hecate Strait (British Columbia), San Juan Islands (Washington) (Laubitz 1970); off Humboldt Bay (Martin 1977); Mazatlán is the most southerly record of C. mendax if validity of species is confirmed., Published as part of Sánchez-Moyano, J. E., García-Asencio, I. & Guerra-García, J. M., 2014, Littoral caprellids (Crustacea: Amphipoda) from the Mexican Central Pacific coast, with the description of four new species, pp. 77-127 in Journal of Natural History 49 (1) on pages 89-93, DOI: 10.1080/00222933.2014.937366, http://zenodo.org/record/4002539, {"references":["Mayer P. 1903. Die Caprellidae der Siboga-Expedition. Siboga-Expeditie. 34: 1 - 160.","Laubitz DR. 1970. Studies on the Caprellidae (Crustacea: Amphipoda) of the American North Pacific. Natl Mus Nat Sci, Ottawa, Pub Biol Oceanogr. 1: 1 - 89.","Dougherty EC, Steinberg EE. 1953. Notes on the skeleton shrimps (Crustacea: Caprellidae) of California. Proceed Biol Soc Wash. 66: 39 - 50.","McCain JC. 1968. The Capreillidae (Crustacea: Amphipoda) of the Western North Atlantic. US Natl Mus Bull. 278: 1 - 147. doi: 10.5479 / si. 03629236.278","Watling L, Carlton JT. 2007. Caprellidae. In: Carlton JT, editor. The light and smith manual of the intertidal invertebrates from central California to Oregon. Berkeley and Los Angeles, California: University of California Press; p. 618 - 628.","Martin DM. 1977. A survey of the family Caprellidae (Crustacea: Amphipoda) from selected sites along the northern California coast. Bull South Calif Acad Sci. 76: 146 - 167.","Hammer RM, Zimmerman RC. 1979. Species of demersal zooplankton inhabiting a kelp forest ecosystem off Santa Catalina Island, California. Bull South Calif Acad Sci. 78: 199 - 206."]}

Caprella pitu sp. nov. (Figures 9–14) Type material Holotype male (MNCN 20.04 /9211), Allotype female (MNCN 20.04 /9212), Paratypes: 7 males (MNCN 20.04 /9213-19), 4 females (MNCN 20.04 /9220-23). Additional material examined Five males (MNCN 20.04 /9224), 5 females (MNCN 20.04 /9225), collected from Cerro Pelón (Isla Isabel), México, 25 m, on gorgonians (Pacifigorgia cf. agassizii); St1: 108 males, 110 females, 96 juveniles; St 2: 4 males, 1 juveniles; St 7: 212 males, 245 females, 326 juveniles; St 8: 272 males, 356 females, 446 juveniles; St 9: 17 males, 18 females; St 10: 7 males, 19 females. Type locality Isla de Los Pájaros (Mazatlán), México, 3–6 m, on gorgonians (Leptogorgia rigida and Leptogorgia peruviana). Etymology The species is dedicated to Emilio Sánchez ‘Pitu’, son of the first and second authors; used as a noun in apposition. Diagnosis Head with rostrum short and triangular. Body stout and wide with tiny tubercles. Peduncle of antenna 1 scarcely setose. Gnathopod 2 basis short with an anterior carina; palm of propodus with a acute projection medially and a rounded distal one. Pereopod 5–7 with carpus elongated and palm of propodus without grasping spines. Description Male holotype. Body length: 8.7 mm. Lateral and dorsal view (Figure 9): Head rostrum short and triangular. Body stout and slightly flattened, with numerous tiny tubercles. Pereonites 2–7 decreasing in length respectively. In dorsal view, body wide, with lateral and flat expansions especially in pereonites 3 and 4 (about as wide as long). Strong pleural development. Gills (Figure 9): Present on pereonites 3–4, rounded. Mouthparts (Figure 10): Upper lip symmetrically bilobed with small setulae apically. Mandibles without palp, mandibular molar process strong, incisor and lacinia mobilis five-toothed, left and right mandible with three and two pectinated setae, respectively. Lower lip with inner lobes well-demarcated, inner and outer lobes setose apically. Maxilla 1 outer lobe with seven robust setae, distal article of the palp with six apical robust setae and 12 lateral setae. Maxilla 2 inner lobe oval and outer lobe rectangular, about 1.5 times as long as the inner lobe. Maxilliped inner plate oval with two robust and short setae and eight plumose setae; outer plate with four robust setae and eight long setae; palp four-articulate, with numerous long setae, article 4 with row of setulae on its grasping margin. Antennae (Figure 9 and 11): Antenna 1 about half of body length; peduncle scarcely setose; article 1 and 2 enlarged; flagellum nine-articulate. Antenna 2 flagellum two-articulate and setose, carrying robust setae in the distal article; swimming setae present. Gnathopods (Figure 11): Gnathopod 1 basis as long as ischium, merus and carpus combined, with a anterior denticulate carina and tiny tubercles; propodus palm with two proximal grasping spines and setae along the palm; dactylus elongate with rows of setulae. Gnathopod 2 inserted in the middle of pereonite 2 and with numerous tiny tubercles along all surface; basis short, about one-sixth as long as total length of gnathopod, with an anterior carina; propodus oval, length about 1.5 times width, palm of propodus without grasping spines, with an acute projection medially and a rounded distal one; dactylus short and wide with tiny tubercles. Pereopods (Figure 12): Pereopods 3 and 4 absent. Pereopod 5–7 robust and increasing in length; basis, merus and carpus with a posterior carina with rows of setae; carpus elongated; palm of propodus without grasping spines; dactylus short and robust. Penes (Figure 12): Situated medially, rounded. Abdomen (Figure 12): With a pair of two-articulated appendages, a pair of lateral lobes and a single dorsal lobe. Allotype female. Body length: 5.2 mm. Similar to male (Figures 9 and 11). Body wide, especially in pereonites 3 and 4 (width about twice length). Oostegites present, being slightly setose on pereonite 3. Antenna 1 peduncle not enlarged. Gnathopod 2 similar to male but propodus palm with a minor excavation between medial and distal projections. Abdomen with a pair of lateral lobes and a single dorsal lobe (Figure 12). Intraspecific variation Most of the morphological characters from C. pitu were rather constant. However, there are slightly differences between populations from the type locality and other sites based especially on body length and the morphology of the pereopods 5–7 (Figures 9 and 13). In the type locality (Mazatlán), the individuals were more robust and longer than in other localities further south such as Isla Isabel and Bahía Banderas (length varied from 8.7 to 7.8 mm in males, and 5.2 to 4.3 mm in females). The length of the pereopods was apparently larger in specimens from Isla Isabel and these specimens were referred to as a ‘long-leg’ form. These differences are based mainly on the ratio between width and length of the merus and propodus (independently for males or females), which gives a relative appearance of greater length. For example, the propodus of pereopod 7 was one-third as wide as long in Mazatlán versus one-quarter in Isla Isabel; and the carpus was one-half and one-third, respectively (Figures 12 and 14). Remarks The new species is close to Caprella penantis Leach, 1814 in the general shape of the body. Caprella penantis is considered a cosmopolitan species with remarkable intraspecific morphological variation (Mayer 1903; McCain 1968; Laubitz 1972; Cabezas et al. 2010) and the taxonomic status of the different forms has been controversial for years (Cabezas et al. 2013). Although C. penantis has been cited through the Pacific Ocean, the nearest record to the Mexican Pacific coast was cited by Laubitz (1972) from Monterey Bay but without location, date of collection or drawings. According to Watling and Carlton (2007), C. penantis could be an introduction to the California coast. Laubitz (1972) wrote that specimens of C. penantis from California were less setose and smaller than specimens from the Atlantic, but they showed the typical stout body and strong pleural development. In fact, our specimens are clearly smaller than C. penantis (8.7 mm as opposed to 14 mm). Recently, a genetic and morphological study on the C. penantis group has refuted the cosmopolitan distribution of this species and has highlighted the existence of at least four species (Cabezas et al. 2013). Our specimens were included in this study as ‘ C. penantis from Mexico’ and the results demonstrated that it represents a different species from the C. penantis group. Additionally, Cabezas et al. (2013) pointed out the reciprocal monophyly of the two forms of C. pitu and suggested that the absence of gene flow between populations from Mazatlán and Isla Isabel could be an indication of the existence of two distinct species. However, we have considered these as a single species due to the scarcity of morphological differences between both forms and until more detailed studies can be carried out. Caprella pitu and C. penantis can be distinguished mainly on the basis of the following characteristics: male gnathopod 2 propodus less setose and with medial projection in C. pitu and with proximal projection in C. penantis (or without projection in some varieties); female gnathopod 2 propodus similar to male in C. pitu, with medial projection, small excavation and distal rounded projection, while in C. penantis female gnathopod 2 propodus is different to male with palm slightly convex with a pair of proximal grasping spines; propodus periopod 5–7 without proximal grasping spines in C. pitu, versus with grasping spines in C. penantis; carpus of periopod 5–7 elongate in C. pitu (half as wide as long in pereopod 7) and subquadrate in C. penantis. McCain (1968) reported the absence or reduction of grasping spines on the propodus of pereopods 5–7 in specimens of C. penantis taken on the gorgonian Leptogorgia from Florida. Caprella pitu has been found exclusively on gorgonians and, in agreement with Aoki and Kikuchi (1995) for Caprella andreae, the adaptation to an ecologically isolated habitat such as gorgonians could have led to its speciation. Potentially, the material of McCain (1968) lacking grasping spines could also belong to a different species. Another morphologically similar species from the California coast is Caprella natalensis Mayer, 1903 (= C. angusta in Dougherty and Steinberg 1953, and Laubitz 1970). It is considered to be the Pacific coast equivalent of C. penantis (Laubitz 1972) and it is very abundant along the California coast (Dougherty and Steinberg 1953; Martin 1977; Watling and Carlton 2007). The main differences between C. pitu and C. natalensis are basically similar to the differences with C. penantis. Additonally, the three species can be differentiated because pereonite 5 is usually longer than pereonites 6 and 7 in C. natalensis whereas in C. pitu and C. penantis it is shorter (three pereonites are subequal). Pleural development is not present in adults of C. natalensis. Habitat Caprella pitu has been found exclusively clinging to several species of gorgonians (Leptogorgia sp., Leptogorgia rigida, Leptogorgia peruviana, Pacifigorgia sp and Pacifigorgia cf. agassizii) from 2 to 25 m deep. It was more abundant on L. rigida and P. cf. agassizii (some samples with more than 500 individuals). In some samples from Mazatlán, it shared the substrates with other species such as Aciconula acanthosoma and Caprella mendax; however it was the only species in the samples from Isla Isabel and Bahía Banderas. Distribution The typical form has been collected from Mazatlán (St1, Isla de los Pájaros; St2, Isla Venado), whereas the ‘long-leg’ form is known from Isla Isabel (St7, Las Monas; St8- Cerro Pelón) and Bahía Banderas (St9- Islas Marietas; St10, Los Arcos)., Published as part of Sánchez-Moyano, J. E., García-Asencio, I. & Guerra-García, J. M., 2014, Littoral caprellids (Crustacea: Amphipoda) from the Mexican Central Pacific coast, with the description of four new species, pp. 77-127 in Journal of Natural History 49 (1) on pages 93-102, DOI: 10.1080/00222933.2014.937366, http://zenodo.org/record/4002539, {"references":["Leach WE. 1814. Crustaceology. Edinb Encyclopaedia. 7: 383 - 434.","Mayer P. 1903. Die Caprellidae der Siboga-Expedition. Siboga-Expeditie. 34: 1 - 160.","McCain JC. 1968. The Capreillidae (Crustacea: Amphipoda) of the Western North Atlantic. US Natl Mus Bull. 278: 1 - 147. doi: 10.5479 / si. 03629236.278","Laubitz DR. 1972. The Caprellidae (Crustacea, Amphipoda) of Atlantic and Arctic Canada. Natl Mus Nat Sci, Ottawa, Publ Biol Oceanogr. 4: 1 - 82.","Cabezas MP, Guerra-Garcia JM, Baeza-Rojano E, Redondo-Gomez M, Figueroa E, Luque T, Garcia-Gomez JC. 2010. Exploring molecular variation in the cosmopolitan Caprella penantis (Crustacea: Amphipoda): results from RAPD analysis. J Mar Biol Assoc U K. 90: 617 - 622. doi: 10.1017 / S 0025315409990828","Cabezas MP, Cabezas M, Machordom A, Guerra-Garcia JM. 2013. Hidden diversity and cryptic speciation refute cosmopolitan distribution in Caprella penantis (Crustacea: Amphipoda: Caprellidae). J Zool Syst Evol Res. 51: 85 - 99. doi: 10.1111 / jzs. 12010","Watling L, Carlton JT. 2007. Caprellidae. In: Carlton JT, editor. The light and smith manual of the intertidal invertebrates from central California to Oregon. Berkeley and Los Angeles, California: University of California Press; p. 618 - 628.","Aoki M, Kikuchi T. 1995. Notes on Caprella andreae Mayer, 1890 (Crustacea, Amphipoda) from the carapace of loggerhead sea turtles in the East China Sea and in Kyushu, Japan. Proc Jpn Soc Syst Zool. 53: 54 - 61.","Dougherty EC, Steinberg EE. 1953. Notes on the skeleton shrimps (Crustacea: Caprellidae) of California. Proceed Biol Soc Wash. 66: 39 - 50.","Laubitz DR. 1970. Studies on the Caprellidae (Crustacea: Amphipoda) of the American North Pacific. Natl Mus Nat Sci, Ottawa, Pub Biol Oceanogr. 1: 1 - 89.","Martin DM. 1977. A survey of the family Caprellidae (Crustacea: Amphipoda) from selected sites along the northern California coast. Bull South Calif Acad Sci. 76: 146 - 167."]}

Caprella equilibra Say, 1818 (Figure 3–5) Caprella equilibra Say 1818: 391–392; McCain 1968: 25, figs 12–13; McCain and Steinberg 1970: 19; Cavedini 1982: 500; Krapp-Schickel 1993: 782–783, fig. 533. Caprella aequilibra Mayer 1882: 45, pl. 1, fig. 7; pl. 2, figs 1–11; pl. 4, figs 20–25; pl. 5, figs 16–18; Chevreaux and Fage 1925: 455, fig. 433. Material examined St6: 300 males, 250 females, 500 juveniles; St7: 19 males, 6 females, 21 juveniles; St8: 50 males, 35 females, 100 juveniles. Remarks The morphology of the specimens observed is in agreement with the description and figures included in Krapp-Schickel (1993) for Mediterranean specimens. This cosmopolitan species has a distinctive ventral projection between gnathopods 2, head with rectangular rostrum, gnathopod 2 basis robust and short with high and denticulate anterior carina. The largest male length found during the present study was 10 mm in length. Taking into account that Krapp-Schickel (1993) found specimens up to 20 mm, presumably our specimens are subadults. However, this variation could also be attributed to environmental variation between different geographical regions. Three species with similar characteristics have been described from the North American Pacific coast: Caprella equilibra, Caprella mendax Mayer, 1903 and Caprella pilidigita Laubitz, 1970. All of them show the ventral projection between gnathopods 2. According to Laubitz (1970), C. pilidigita is clearly different from the others, especially based on the structure of gnathopod 2 (dactylus with hairs along inner margin, propodus three times as long as broad, basis one-third of total appendage) and the setation of antenna 1. Caprella mendax was described by Mayer (1903) but its distinction from C. equilibra is very tenuous (some authors such as Dougherty and Steinberg (1953) and Stoddart and Lowry (2003) consider C. mendax to be a synonym of C. equilibra). In fact, our specimens showed characteristics of both species as summarized in Table 2. Widespread species such as C. equilibra can show natural morphological variation in their range or may encompass cryptic species. Disentangling species boundaries and/or cryptic species is a common issue for a great number of marine groups and especially for crustaceans (Cabezas et al. 2013, and references therein). In this sense, Cabezas et al. (2013) provided the first evidence for cryptic species in Caprellidae with a study of the cosmopolitan species Caprella penantis Leach, 1814, and supporting evidence that this species is a complex of at least four species. However, another study on the exotic Paracaprella pusilla Mayer, 1890 has demonstrated that this species exhibits great genetic uniformity throughout its distribution range (Ros et al. 2013). In the case of C. equilibra, further studies are necessary to clarify this issue. Due to this and the presumable absence of superadult males, the material examined has been assigned to C. equilibra despite a certain similarity with C. mendax, such as the length of pereonite 5 larger than pereonite 4 or antenna 1 length. Habitat Caprella equilibra has been found on a great variety of substrates such as seaweeds, hydroids, bryozoans, sponges or ascidians from the intertidal to 3000 m deep (Krapp- Schickel 1993). In the present study, C. equilibra was more abundant on hydroids and bryozoans, scarce on gorgonians (Pacifigorgia cf. agassizii) and absent on seaweeds. Despite its worldwide distribution and ubiquity of substrates, it has been only found in Isla Isabel within our study area. Guerra-García and Tierno de Figueroa (2009) included C. equilibra as detritivorous predators based on a high percentage of detritus in the gut content (> 80%) besides hydroids (> 7%) and copepods (> 6%). More recently, Alarcón-Ortega et al. (2012) showed with material from the present study that the gut content of C. equilibra was approximately 40% of both detritus and hydroids, so that the substrate is not only used as habitat but can also be a source of food. Distribution Type locality. South Carolina. Other records: cosmopolitan species (McCain 1968; Krapp-Schickel 1993; Guerra-García 2004)., Published as part of Sánchez-Moyano, J. E., García-Asencio, I. & Guerra-García, J. M., 2014, Littoral caprellids (Crustacea: Amphipoda) from the Mexican Central Pacific coast, with the description of four new species, pp. 77-127 in Journal of Natural History 49 (1) on pages 84-89, DOI: 10.1080/00222933.2014.937366, http://zenodo.org/record/4002539, {"references":["Say T. 1818. An account of the Crustacea of the United States. J Acad Nat Sci Philadelphia. 1: 374 - 401.","McCain JC. 1968. The Capreillidae (Crustacea: Amphipoda) of the Western North Atlantic. US Natl Mus Bull. 278: 1 - 147. doi: 10.5479 / si. 03629236.278","McCain JC, Steinberg JE. 1970. Amphipoda-I, Caprellidea-I. Crustaceorum Catalogus. 2: 1 - 78.","Cavedini P. 1982. Contributo alla conoscenza dei Caprellidi del Mediterraneo (Crustacea, Amphipoda). Boll Mus Civ St Nat Verona. 8: 493 - 531.","Krapp-Schickel T. 1993. Suborder Caprellidea. In: Ruffo S, editor. The Amphipoda of the Mediterranean. Mem Inst Oceanogr Monaco. 13: 773 - 809.","Mayer P. 1882. Caprelliden. Fauna und flora des golfes von Neapel und der angrerzenden Meeres-Abschnitte. 6: i- x, 1 - 201.","Chevreaux E, Fage L. 1925. Amphipodes. Faune de France. 9: 1 - 488.","Mayer P. 1903. Die Caprellidae der Siboga-Expedition. Siboga-Expeditie. 34: 1 - 160.","Laubitz DR. 1970. Studies on the Caprellidae (Crustacea: Amphipoda) of the American North Pacific. Natl Mus Nat Sci, Ottawa, Pub Biol Oceanogr. 1: 1 - 89.","Dougherty EC, Steinberg EE. 1953. Notes on the skeleton shrimps (Crustacea: Caprellidae) of California. Proceed Biol Soc Wash. 66: 39 - 50.","Stoddart HE, Lowry JK. 2003. Zoological catalogue of Australia. Crustacea: Malacostraca: Peracarida: Amphipoda, Cumacea, Mysidacea. Volume 19.2 B. Victoria, Australia: CSIRO Publishing.","Cabezas MP, Cabezas M, Machordom A, Guerra-Garcia JM. 2013. Hidden diversity and cryptic speciation refute cosmopolitan distribution in Caprella penantis (Crustacea: Amphipoda: Caprellidae). J Zool Syst Evol Res. 51: 85 - 99. doi: 10.1111 / jzs. 12010","Leach WE. 1814. Crustaceology. Edinb Encyclopaedia. 7: 383 - 434.","Mayer P. 1890. Die Caprelliden des Golfes von Neapel und der angrenzenden Meeres- Abschnitte. Fauna Flora Golf Neapel. 17: 1 - 55.","Ros M, Vazquez-Luis M, Guerra-Garcia JM. 2013. The tropical caprellid amphipod Paracaprella pusilla: a new alien crustacean in the Mediterranean Sea. Helgol Mar Res. doi: 10.1007 / s 10152 - 013 - 0353 - 4","Guerra-Garcia JM, Tierno de Figueroa JM. 2009. What do caprellids (Crustacea: Amphipoda) feed on? Mar Biol. 156: 1881 - 1890. doi: 10.1007 / s 00227 - 009 - 1220 - 3","Alarcon-Ortega LC, Guerra-Garcia JM, Sanchez-Moyano JE, Cupul-Magana FG. 2012. Feeding habits of caprellids (Crustacea: Amphipoda) from the west coast of Mexico. Do they feed on their hosting substrates? Zool baetica. 23: 11 - 20.","Guerra-Garcia JM. 2004. The Caprellidea (Crustacea, Amphipoda) from Western Australia and Northern Territory, Australia. Hydrobiologia. 522: 1 - 74. doi: 10.1023 / B: HYDR. 0000029929.07691. a 7"]}

Liropus isabelensis sp. nov. (Figures 15–18) Type material Holotype male plus 1 slide (MNCN 20.04 /9226), Allotype female plus 1 slide (MNCN 20.04 /9227). Paratypes: 2 males (MNCN 20.04 /9228-29), 1 female (MNCN 20.04 /9230). Additional material examined St1: 1 male; St6: 3 males, 3 females; St8: 3 males, 1 female, 1 juvenile. Type locality Cerro Pelón (Isla Isabel), México, 25 m, on hydroids and bryozoans. Etymology Named isabelensis alluding to the National Park of Isla Isabel (Nayarit), México. Diagnosis Eyes present. Body dorsally smooth. Anterolateral acute and downward-directed projections on pereonite 2 and mediolateral on pereonite 3 in males and absent in females. Flagellum of antenna 1 five-articulate. Gnathopod 2 basis slightly longer than pereonite 2; ischium and propodus elongated. Pereopods 3, 4 and 5 one-articulate. Abdomen without appendages in males. Description Male holotype. Body length: 3.25 mm. Lateral and dorsal view (Figure 15): Body dorsally smooth. Head rounded, eyes present. Pereonite 1 fused with head, suture present. Pereonite 2 with a pair of anterolateral acute and directed downwards projections. Pereonite 3 with a pair of mediolateral projections. Pereonite 5 the longest. Pereonite 7 the shortest. Gills (Figure 15): Present on pereonites 3–4, oval. Gills on pereonite 3 about 2.5 times longer than those on pereonite 4. Mouthparts (Figure 16): Upper lip symmetrically bilobed with small setulae apically. Mandibles with molar process and three-articulate palp; distal article of palp the longest, with one seta apically (lost in the dissection); second article of palp with one distal plumose seta; incisor and lacinia mobilis five-toothed; left and right mandibles with three and two pectinated setae respectively. Lower lip with inner lobes well-demarcated, inner and outer lobes setose apically. Maxilla 1 outer lobe carrying five robust setae; distal article of the palp with five apical setae. Maxilla 2 inner lobe oval, carrying five distal setae, and outer lobe rectangular, with six apical setae. Maxilliped inner plate rectangular carrying from inner to outer margin a nodular seta, two plumose setae and one seta; outer plate with four setae and one plumose seta apically; palp four-articulate, scarcely setose, third article provided with a projection. Antennae (Figures 15 and 17): Antenna 1 about one-third of body length; peduncle scarcely setose; flagellum five-articulate. Antenna 2 about two-thirds of antenna 1; proximal peduncular article with a developed acute projection distally; swimming setae absent; flagellum two-articulate. Gnathopods (Figure 17): Gnathopod 1 basis longer than ischium, merus and carpus combined (length about 1.5 times); propodus palm with proximal grasping spine and setae along the palm present. Gnathopod 2 inserted on the anterior half of pereonite 2; basis slightly longer than pereonite 2, with tiny tubercles on the proximal half; ischium elongated, half as long as basis; merus rounded; carpus short and triangular; propodus elongated, longer than basis, and four times as long as wide; palm with proximal projection with one grasping spine, followed by another proximal acute projection, margin setose; dactylus with setulae and widened medially. Pereopods (Figure 18): Pereopod 3 and 4 small, one-articulate, with three or four setae apically, respectively. Pereopod 5 one-articulate, with five setae and one plumose seta apically. Pereopod 6–7 increasing in length, six-articulate and attached to the posterior end of the pereonite; propodus palm carrying a row of robust setae. Penes (Figure 18): Situated medially, rounded. Abdomen (Figure 18): A pair of lateral lobes, and a single dorsal lobe. Allotype female. Body length: 2.6 mm. Similar to male except for the following characteristics (Figures 15 and 17): oostegites present, being slightly setose on pereonite 3 and 4; pereonite 2 and 3 lacking anterolateral and lateral projections, respectively; gnathopod 2 ischium less elongated than in male (one-quarter as long as basis), propodus oval, as long as basis, with only one proximal projection, dactylus not setose. Abdomen with a pair of lateral lobes and single dorsal lobe (Figure 18). Remarks Liropus isabelensis represents the 10th species from the genus Liropus Mayer, 1890. The other species included in the genus are as follows: L. africanus Mayer, 1920, L. azorensis Guerra-García, 2004, L. cachuchoensis Guerra-García, 2008, L. elongatus Mayer, 1890, L. gracilis Chevreux, 1927, L. japonicus Mori, 1995, L. minimus Mayer, 1890, L. minusculus Guerra-García and Hendrycks, 2013 and L. nelsonae Guerra-García, 2003. Most of the species have an Atlantic or Mediterranean distribution except L. japonicus, from Japanese waters, and L. minusculus, from California, USA. Therefore, the new species is the second record of the genus Liropus from the East Pacific coast. A morphological comparison among Liropus species is given in Table 3. Liropus isabelensis can be distinguished from all other species mainly by the following characteristics: anterolateral acute and downwards-directed projections on pereonite 2, presence of mediolateral projections on pereonites 3 and gnathopod 2 ischium elongated. Liropus minusculus is the geographically nearer species and shares some characteristics with L. isabelensis such as pereopod 5 one-articulate and the anterolateral projections in pereonite 2 although this is more acute and downwards directed in the latter. Both species have the smallest size, although L. africanus and L. japonicus are also characterized by a very small size. Habitat This species was found attached to species of Thecata and Athecata hydroids, gorgonian (Muricea cf. californica), a bryozoan (Bugula sp.), the seaweed Zonaria cf. farlowii with epiphytic hydroids and several red seaweeds. They occur from 3 to 25 m deep, although always in low densities. Other caprellids, such as Paracaprella spp. and Aciconula acanthosoma, live on these substrates together with L. isabelensis. Distribution Liropus isabelensis has been found from the type locality, Isla Isabel, México (St 6, Bahía Tiburón; St 8, Cerro Pelón), and Mazatlán (St 1, Isla de los Pájaros).

Paracaprella carballoi sp. nov. (Figures 19–22) Type material Holotype male plus 5 slides (MNCN 20.04 /9231), Allotype female (MNCN 20.04 / 9232). Paratypes: 2 males (MNCN 20.04 /9233-34), 4 females (MNCN 20.04 / 9235-38). Additional material examined St1: 20 males, 19 females, 15 juveniles. Type locality Isla de los Pájaros (Mazatlán), México, 3–6 m, on the seaweed Zonaria cf. farlowii with epiphytic hydroids. Etymology The species is dedicated to Dr José Luis Carballo for his important contribution to the knowledge of the benthic fauna from the Pacific coast of México. Diagnosis Head rounded. Pereonite 2 with a rounded and narrow anteroventral projection in adult males, absent in females. Mandibles with molar process and palp reduced to a long seta. Flagellum of antenna 1 nine-articulate. Propodus of gnathopod 2 palm with rectangular projection proximally, carrying two proximal grasping spines and a distal robust tooth. Pereopod 3 and 4 two-articulate. Pereopod 5–7 without grasping spines. Abdomen with a pair of setose uni-articulate appendages. Description Male holotype. Body length: 5 mm. Lateral view (Figure 19): Head rounded. Pereonite 1 fused with head, suture present. Body dorsally smooth, except anterodorsal blunt protuberance on pereonite 2 (absent in immature males). Pereonite 2 with a rounded and narrow anteroventral projection. Pereonite 3 the longest. Pereonite 7 the shortest. Gills (Figure 19): Present on pereonites 3–4, oval. Gills on pereonite 3 about twice as long as those on pereonite 4. Mouthparts (Figure 20): Mandibles with molar process and palp reduced to a long seta; incisor and lacinia mobilis five-toothed; left and right mandibles with three and two pectinated setae, respectively. Maxilla 1 outer lobe carrying six robust-stout setae; distal article of the palp with three robust-stout setae and three marginal setae. Maxilla 2 inner lobe oval, carrying four distal setae, and outer lobe elongated, with five apical setae. Maxilliped inner plate rectangular carrying three setae apically; outer plate with six submarginal and two apical setae; palp four-articulate, setose; third article provided with a large distal process and setose apically; terminal article with a row of setulae on grasping margin, and one seta subdistally. Upper and lower lip lost in dissection. Antennae (Figures 19 and 21): Antenna 1 shorter than the combined lengths of head and pereonite 2–3. Peduncle scarcely setose; flagellum nine-articulate. Antenna 2 a little shorter than peduncle of antenna 1; proximal peduncular article with a small acute projection distally; swimming setae absent; flagellum two-articulate, proximal article c. 2.5 times the length of the distal one. Gnathopods (Figure 21): Gnathopod 1 basis as long as ischium, merus and carpus combined; propodus palm with a single proximal grasping spine; grasping margin of propodus serrated with setae; distal ventral margin of dactylus with one tooth. Gnathopod 2 inserted on the anterior half of pereonite 2; basis elongated slightly shorter than pereonite 2, with two distal short processes on lateral margin; propodus length about twice width; propodus palm with rectangular projection proximally, carrying two proximal grasping spines and a distal robust tooth; grasping margin setose; dactylus thickened medially and setose. Pereopods (Figures 19 and 22): Pereopod 3 and 4 two-articulate, both with four setae apically on distal article and two setae subdistally on basal article. Pereopod 5–7 increasing in length, six-articulate and attached to the posterior end of the pereonite, with several plumose setae. Palm of propodus of pereopod 5 with a proximal short knob bearing a small spine; palm of pereopod 6–7 with several proximal short knobs, each bearing a small spine. Grasping spines absent. Penes (Figure 22): Penes short, situated laterally. Abdomen (Figure 22): A pair of setose uni-articulate appendages, a pair of lateral lobes, and a single dorsal lobe. Allotype female. Body length: 4.4 mm. Similar to male except for the following morphological characteristics (Figures 19 and 21): oostegites present, being slightly setose on pereonite 3 and 4; anterolateral projection on pereonite 2 absent; flagellum of antenna 1 eight-articulate; propodus of gnathopod 2 oval, with a proximal knob bearing a grasping spine, dactylus not setose. Abdomen with a pair of lateral lobes and single dorsal lobe carrying two setae (Figure 22). Habitat Paracaprella carballoi was mainly found attached to the seaweed Zonaria cf. farlowii with abundant small hydroids on underside of thallus, between 3–6 m depth. On these substrates it was relatively abundant. Also it has been found on the gorgonian Leptogorgia rigida, although in low densities. Other caprellids on these substrates were Aciconula acanthosoma, Caprella mendax, C. pitu and Liropus isabelensis. Distribution Paracaprella carballoi has been found so far from the type locality, Isla de los Pájaros (Mazatlán), México.

Paracaprella isabelae sp. nov. (Figures 23–26) Type material Holotype male (MNCN 20.04 /9239), Allotype female (MNCN 20.04 /9240). Paratypes: 4 males (MNCN 20.04 /9241-44), 4 females (MNCN 20.04 /9245-48). Additional material examined St6: 12 males, 14 females, 34 juveniles; St7: 65 males, 56 females, 32 juveniles; St8: 12 males, 5 females, 3 juveniles. Type locality Las Monas (Isla Isabel), México, 6 m, on hydroids and bryozoans. Etymology The species is dedicated to Isabel Sánchez, daughter of the first and second authors. She was born just after the sample survey of this study. Diagnosis Head rounded and dorsally humped. Large bifid sharp-pointed anterolateral projection on anterior margin of pereonite 2 in males, simple and rounded in females. Pereonite 3 with a rounded anterolateral projection in males. Short ventral forwarddirected projection with ‘raspberry’-like surface between the gnathopods 2. Mandibles with molar process and without palp. Flagellum of antenna 1 10-articulate. Coxa of gnathopod 2 with a tubercle with ‘raspberry’-like surface in males. Propodus palm of gnathopod 2 with rectangular projection proximally, bearing one proximal grasping spine and a distal long robust tooth in males. Pereopod 3 and 4 two-articulate. Pereopod 5–7 without grasping spines. Abdomen with a pair of setose uni-articulate appendages in males. Description Male holotype. Body length: 5.4 mm. Lateral and dorsal view (Figure 23): Head rounded and dorsally humped, eyes present. Pereonite 1 fused with head, suture present. Body dorsally smooth, except blunt dorsal protuberance in the middle of pereonites 2–3. Large adult with other blunt dorsal posterior protuberance on pereonite 2. Large bifid sharp-pointed anterolateral projection on anterior margin of pereonite 2. It has a short ventral forwarddirected projection with ‘raspberry’-like surface between gnathopods 2. Pereonite 3 with a rounded anterolateral projection. Pereonite 3 the longest. Pereonite 7 the shortest. Gills (Figure 23): Present on pereonites 3–4, oval. Gills on pereonite 3 about twice as long as those on pereonite 4. Mouthparts (Figure 24): Upper lip symmetrically bilobed without setulae apically. Mandibles with molar process and without palp; incisor and lacinia mobilis five-toothed; left and right mandibles with three and two pectinated setae, respectively. Lower lip with inner lobes well-marked and with a medial suture, outer lobes setose apically. Maxilla 1 outer lobe carrying six robust-stout setae; distal article of the palp with three robust and two long apical setae. Maxilla 2 inner lobe oval, carrying four distal setae, and outer lobe elongated, with five apical setae. Maxilliped inner plate rectangular carrying three setae apically; outer plate with six submarginal setae; palp four-articulate, scarcely setose; third article provided with a large distal process and setose apically; terminal article with a row of setulae on grasping margin, and two setae subdistally. Antennae (Figures 23 and 25): Antenna 1 shorter than the combined lengths of head and pereonite 2–3. Peduncle setose; flagellum 10-articulate. Antenna 2 a little shorter than peduncle of antenna 1; proximal peduncular article with a short acute projection distally; swimming setae absent; flagellum two-articulate, proximal article 2 times the length of the distal one. Gnathopods (Figure 25): Gnathopod 1 basis as long as ischium, merus and carpus combined; propodus palm with a single proximal grasping spine; grasping margin of propodus with setae; ventral margin of dactylus with several teeth. Gnathopod 2 inserted on the anterior half of pereonite 2; coxa bearing anteriorly a tubercle with ‘raspberry’-like surface; basis elongated slightly shorter than pereonite 2, without proximal serrated knob on ventral margin; propodus length about twice width; propodus palm with rectangular projection proximally, carrying one proximal grasping spine and a distal long robust tooth; grasping margin setose; dactylus thickened medially and setose. Pereopods (Figures 23 and 26): Pereopod 3 and 4 two-articulate, with five and four setae apically, respectively, and one seta distally on basal article. Pereopod 5–7 increasing in length, six-articulate and attached to the posterior end of the pereonite, with several plumose setae. Palm of propodus of pereopod 5 with a proximal knob bearing a small spine; palm of pereopod 6–7 with several proximal knobs, each bearing a small spine. Grasping spines absent. Penes (Figure 26): Penes short, situated laterally. Abdomen (Figure 26): A pair of setose uni-articulate appendages, a pair of lateral lobes, and a single dorsal lobe. Allotype female. Body length: 4.2 mm. Similar to male except for the following characteristics (Figures 23 and 25): oostegites present, being slightly setose on pereonite 3; small and rounded anterolateral projection on pereonite 2, lacking anterolateral projection on pereonite 3; flagellum of antenna 1 six-articulate; propodus of gnathopod 2 oval, with a proximal knob bearing a grasping spine and a plumose seta, dactylus not setose. Abdomen with a pair of lateral lobes and single dorsal lobe carrying two plumose setae (Figure 26). Habitat This species has been found on several substrates along the coast of Isla Isabel from 1 to 25 m depth. It was more abundant on hydroids and bryozoan (Bugula sp.) at 6 m depth, although it was also recorded on gorgonians (Pacifigorgia cf. agassizi), and several red seaweeds. Other caprellids such as Aciconula acanthosoma, Caprella pitu, C. equilibra or Liropus isabelensis live on these substrates together with P. isabelae. Distribution Paracaprella isabelae has been found from the type locality, Isla Isabel, México (St 6, Bahía Tiburón; St 7, Las Monas; St 8, Cerro Pelón). Remarks on Paracaprella spp. So far, the genus Paracaprella Mayer, 1890 is represented by eight species: P. alata Mayer, 1903; P. barnardi McCain, 1967; P. crassa Mayer, 1903; P. digitimanus Quitete, 1971; P. guerragarciai Winfield and Ortiz, 2013; P. insolita Arimoto, 1980; P. pusilla Mayer, 1890; and P. tenuis Mayer, 1903. The main differences between Paracaprella spp. and the two new species, P. carballoi and P. isabelae, are summarized in Table 4. Paracaprella insolita has been excluded because only females have been described and it is the only Paracaprella with a characteristic projection dorsally on the head (Arimoto 1980). Paracaprella carballoi is morphologically close to P. barnardi and P. pusilla, but can be distinguished by the following characters: both P. carballoi and P. pusilla have a smooth body dorsally with an anterodorsal blunt protuberance on pereonite 2, whereas P. barnardi has a large tubercle in this position; the anterolateral projection of pereonite 2 is rounded and narrow as opposed to the sharp-pointed projection in the others; pereonite 4 and 5 are subequal in length whereas pereonite 3 is the longest; (1971), Laubitz (1972), Arimoto (1976), Sivaprakasam (1977), Diaz et al. (2005), Guerra-García et al. (2006) and Winfield and Ortiz (2013). P. insolita excluded. (Continued) Table 4. (Continued). Gnathopod 2 propodus Rectangular, one Rectangular, one Rectangular, two Rectangular, three Quadrate, one Quadrate, a Rectangular, one grasping Rectangular, one Rectangular palm, proximal grasping spine and grasping spine grasping teeth grasping grasping spine spine and long-robust grasping spine and large, projection short-robust tooth and short- spine and spine, short- and long-robust tooth and robust one small robust tooth robust tooth robust tooth tooth tooth grasping and a spine and digitiform short- projection robust tooth Gnathopod 1 propodus 1 1 1? 1 2 1 1 1 palm, no. of proximal grasping spine Mandibular palp Absent A simple seta A simple seta? Absent A simple seta Absent A simple seta Variable, a simple seta to three- articulated basis of gnathopod 2 elongated without proximal serrated knob but with two distal short processes on lateral margin; gnathopod 2 propodus palm with rectangular proximal projection bearing two grasping spines, but only one in all other species of the genus (except P. crassa, without grasping spines and carrying three teeth); and mandibular palp as a simple seta (similar to P. barnardi, P. pusilla and P. guerragarciai). Paracaprella isabelae can be distinguished from all other species mainly by the following characteristics: head rounded and dorsally humped (similar to P. crassa, with which it also shares a blunt posterior protuberance on pereonite 2); large and bifid sharp-pointed anterolateral projection on pereonite 2 (in other species can be sharp-pointed but always single); rounded anterolateral projections on pereonite 3 (similar to P. alata although triangular on pereonite 3 and small and rounded on pereonite 4 in this case; triangular in P. digitimanus; and absent in the other species of the genus); short ventral forward directed projection with ‘raspberry’-like surface between gnathopods 2; pereonite 4 and 5 subequal in length and pereonite 3 the longest, similar to P. carballoi; and mandibular palp absent as is the case of P. alata and P. digitimanus. According to Winfield and Ortiz (2013), the genus Paracaprella has a geographic distribution encompassing temperate, subtropical and tropical seas. However, only P. barnardi and P. pusilla have been recorded so far from the American Pacific coast. While P. barnardi has a more local distribution (it has only been recorded from the type locality in Culebra Island, Panama), P. pusilla is the species of the genus with a more worldwide distribution and it is the only species found in European waters, presumably introduced by ship fouling (Ros and Guerra-García 2012; Ros et al. 2013), even though it has only been cited from the American coast in Chile (Guerra- García and Thiel 2001). Hence, both P. carballoi and P. isabelae represent the northernmost records of the genus on the East Pacific coast.

Aciconula acanthosoma Chess, 1989, (Figure 2) (Continued) St 8 Cerro Pelón Isla Isabel 21º51 ′ 15.58 ″ N 25 Hydroids (Thecata and Aciconula acanthosoma, 7 105º53 ′ 34.65 ″ W athecata), gorgonians Paracaprella carballoi sp. (Leptogorgia peruviana, L. nov., Caprella pitu sp. nov., rigida, Leptogorgia sp., Caprella equilibra, Liropus Muricea cf. californica, isabelensis sp. nov. Pacifigorgia cf agassizii, Pacifigorgia sp.), bryozoan (Bugula sp.) St 9 Islas Bahía 20º42 ′ 01.75 ″ N 10 Gorgonians Caprella pitu sp. nov. 1 Marietas Banderas 105º33 ′ 50.03 ″ W St 10 Los Arcos Bahía 20º33 ′ 02.35 ″ N 12 Gorgonians Caprella pitu sp. nov. 1 Banderas 105º17 ′ 35.82 ″ W Material examined St1: 41 males, 23 females, 5 juveniles; St2: 2 males; St6: 3 males, 6 females, 5 juveniles; St7: 11 males, 7 females; St8: 30 males, 22 females, 21 juveniles. Remarks The specimens are in agreement with the original description by Chess (1989) with material from Santa Catalina island (California). Typical features of the species are present such as all pereonites dorsally spinose or basis of gnathopod 2 with acute distolateral projection. However, the studied specimens have some intraspecific variation in the head projection pattern compared with the four prominent curved projections from the material type: two anterior prominent and two posterior reduced ones (about one-third of the length of anterior ones). In some specimens from Mazatlán (St1 and St2), one or two posterior projections can be absent or very reduced. The length is slightly smaller in Mexican A. acanthosoma (male to 5.5 mm, female to 4.5 mm) than in the type material (male and female to 7.3 mm and 6.3 mm, respectively). Additionally, pereonites 3 and 4 have fewer lateral spinose projections. Other generic characters are present such as the six-articulate pereopod 5, elongate, with long setae (although slightly less setose than in the original description) and the distal article reduced to a small cone, instead of the typical dactylus. Habitat Aciconula acanthosoma was found attached to different species of Thecata and Athecata hydroids, gorgonians (Leptogorgia rigida, Leptogorgia peruviana, Pacifigorgia sp., Pacifigorgia cf. agassizii, Muricea sp., Muricea cf. californica), a bryozoan Bugula sp., and the seaweed Zonaria cf. farlowii with epiphytic hydroids. Chess (1989) collected specimens from different substrata but they were more abundant on seaweeds (e.g. Cystoseira neglecta, Sargassum palmeri or Zonaria farlowii). In the present study, however, they were more abundant on sessile animals, being absent in most of the sampled seaweeds. Although in temperate ecosystems the highest densities of caprellids can be found in seaweeds (Guerra- García 2001), in the tropical region caprellids are mainly associated with hydroids and secondarily with gorgonians and other corals (Guerra-García 2006; Scinto et al. 2008). The unique available seaweed as substrate, Zonaria cf. farlowii, had a high coverage of hydroids which could indicate a strong relationship between A. acanthosoma and cnidarians. According to Chess (1989), A. acanthosoma feeds on sponges and ascidians. Recently in a study on feeding habits of Pacific Mexican caprellids, Alarcón-Ortega et al. (2012) reported that this species feeds mainly on detritus (75% of the gut content), crustaceans (17.5%) and hydroids (6.7%). In agreement with Guerra- García and Tierno de Figueroa (2009), the caprellid species with molars in mandibles (such as genus Aciconula) are characterized by a diet mainly based on detritus, although in general caprellids are rather opportunistic because they can change their feeding habits depending on the substrates to which they cling. Distribution Type locality. Santa Catalina island, California (USA) (Chess 1989). Other records: Mazatlán and Isla Isabel, Pacific coast of México (Alarcón-Ortega et al. 2012)., Published as part of Sánchez-Moyano, J. E., García-Asencio, I. & Guerra-García, J. M., 2014, Littoral caprellids (Crustacea: Amphipoda) from the Mexican Central Pacific coast, with the description of four new species, pp. 77-127 in Journal of Natural History 49 (1) on pages 78-84, DOI: 10.1080/00222933.2014.937366, http://zenodo.org/record/4002539, {"references":["Chess JR. 1989. Aciconula acanthosoma, new species, a caprellid amphipod from Southern California, with notes on its ecology. J Crust Biol. 9: 662 - 665. doi: 10.2307 / 1548595","Scinto A, Bavestrello G, Boyer M, Previati M, Cerrano C. 2008. Gorgonian mortality related to a massive attack by caprellids in the Bunaken Marine Park (North Sulawesi, Indonesia). J Mar Biol Assoc UK. 88: 723 - 727. doi: 10.1017 / S 002531540800129 X","Alarcon-Ortega LC, Guerra-Garcia JM, Sanchez-Moyano JE, Cupul-Magana FG. 2012. Feeding habits of caprellids (Crustacea: Amphipoda) from the west coast of Mexico. Do they feed on their hosting substrates? Zool baetica. 23: 11 - 20."]}

The present study on the distribution of sofbottom macrofauna along the Guadiana River and nearby areas has made it possible to differentiate among zones with different benthic community compositions in response to their environmental conditions. Five main areas were established: upper, middle, and lower estuary, mouth, and coastal area, which could also be divided into shallower and deeper communities. Because of the nonexistence of any obvious contaminant element, it seems that the differences found among the marine, freshwater and estuarine environments were the reason for the communities' heterogeneity. This was confirmed by multivariate analysis and by the clear enrichment and structuring gradient, from upper to coastal areas, in the communities. El estudio efectuado a lo largo del cauce del río Guadiana y las áreas de influencia ha permitido establecer las zonas donde se desarrollan las distintas comunidades de macrofauna del sedimento como respuesta a las diversas condiciones ambientales. En este sentido, se han delimitado cinco grandes zonas: tramo alto, tramo medio, estuario bajo, desembocadura y área litoral, donde, a su vez, se distinguen las comunidades someras de las profundas. Ante la inexistencia de un elemento contaminante claro, parece que son las diferencias entre el medio marino, el fluvial y el estuarino las que están marcando las distintas composiciones de estas comunidades, como se pone de manifiesto en los análisis multivariantes realizados y por el gradiente de enriquecimiento y estructuración conforme se alcanza un ambiente de mayor influencia marina. Instituto Español de Oceanografía

The cartography of benthic communities is, today, essential to promoting adequate strategies for the use, management and conservation of littoral areas, especially if they are large protected zones. In each zone, cartography is necessary to elaborate a management zoning map, depending on the ecological value of the different benthic communities established and on the local geographical distribution. The methodology used in the elaboration of a map including the benthic communities of the Straits of Gibraltar (0-30 m depth; 40 km of littoral extension), in spite of the complexity of these kinds of objectives, represents an approach to the cartography of the submarine sessile biota of large littoral zones of protected areas. The present study combines physical data (bathymetry and type of substrate), collected using acoustic techniques, and biological data (benthic communities), collected during an intensive sampling programme using scuba (hard bottom: image analysis) and dredging (soft bottom: granulometry and benthic fauna). The information has been geoindexed to be inserted, as different layers, into a Geographic Information System (GIS). La cartografía de las comunidades bentónicas es esencial, actualmente, para promover actuaciones eficientes de uso, gestión y conservación de las zonas litorales, especialmente en el ámbito de grandes espacios litorales protegidos. En cada uno de éstos, la cartografía resulta determinante para la elaboración de un mapa de zonificación de usos, condicionado, en gran medida, por los distintos valores ecológicos que puedan asignarse a las diferentes comunidades bentónicas establecidas y a sus distribuciones geográficas locales. La metodología utilizada en la elaboración del mapa de las comunidades bentónicas del estrecho de Gibraltar (en el intervalo batimétrico 0-30 m y de 40 km de extensión litoral aproximada), dada la complejidad que reviste este tipo de objetivos, supone una aproximación a la cartografía de la biota sésil sumergida, en tramos litorales amplios contenidos en áreas protegidas. Se han combinado, mediante superposición de información, datos físicos de batimetría y tipos de fondo, obtenidos mediante técnicas acústicas y convenientemente cartografiados, con datos biológicos de las comunidades bentónicas, obtenidos en campaña intensiva de buceo científico (con la toma de imágenes en sustrato duro, para su ulterior análisis) y mediante dragado (con registros de granulometría y fauna endobentónica en sustrato blando). La información ha sido georreferenciada adecuadamente para su introducción, como capas independientes, en un sistema de información geográfica (SIG). Instituto Español de Oceanografía

EC Directive 2000/60 of the European Parliament and of the Council of Europe provides for the need to establish ecological regions along European coasts. The present article outlines research carried out in various coastal marine ecosystems as a contribution to the characterization of these ecoregions of the coast of Andalusia (southern Spain). Sampling was undertaken along the coastline in the intertidal zone and sublittoral sediments. The various systems studied all gave very similar results with regard to the ecoregions identified, which is indicative of their robustness. These results consistently identified a main Mediterranean region, which could subsequently be subdivided into two, as well as three main ecoregions in the Atlantic: one from the Straits of Gibraltar to the Bay of Cadiz, and the other two along the Huelva coastline, which are clearly affected by the effluents of major river systems such as the Guadalquivir, Odiel and Tinto. Our results suggest that similar structuring factors are operating within these systems., La Directiva 2000/60 CE del Parlamento Europeo y del Consejo Europeo contempla la necesidad de establecer regiones ecológicas a lo largo del litoral europeo. Con el objetivo de contribuir a la delimitación y caracterización de estas ecorregiones se ha realizado este estudio de varios ecosistemas marinos centrado en el litoral andaluz (sur de España). Los muestreos se realizaron en la franja intermareal rocosa y en sedimentos infralitorales. Los sistemas estudiados dieron resultados similares con respecto a la definición de las distintas ecorregiones. Así, se identificó una gran área mediterránea, que podría dividirse en dos, y otra atlántica, que se divide en tres ecorregiones: una comprende desde el estrecho de Gibraltar hasta la bahía de Cádiz y otras dos emplazadas en el litoral de Huelva caracterizadas por la presencia de importantes efluentes fluviales como el Guadalquivir, el Odiel y el Tinto. Los resultados sugieren que existen factores estructurales similares en estos sistemas., Instituto Español de Oceanografía

Molluscs are the second most diverse of all animal phyla, and occur in many habitat types. They are, therefore, a particularly good phylum with which to compare and contrast differences between ecosystems. Mollusc data from a number of sites along the southern coast of the Iberian Peninsula are analysed to study patterns of diversity and distribution using a range of multivariate techniques. Within each site, data are presented from three locations -fully terrestrial, rocky intertidal and soft bottom benthic (10 m and 20 m depths)- all in close proximity. The species are then classified in relation to morphology and size, and analysed at supraspecific levels to elucidate underlying patterns. The observed patterns are briefly discussed, with particular reference to the differential scope and importance of controlling factors in each ecosystem, such as dispersal processes. The results from the systems are compared and discussed in the context of ecological and evolutionary constraints in Mollusca., Los moluscos constituyen el segundo filo animal más diverso y se encuentran en muchos tipos de hábitat, por lo que son idóneos para establecer comparaciones entre distintos ecosistemas. Se han analizado los datos de los moluscos obtenidos en una serie de emplazamientos que cubrían el sur de la península Ibérica para determinar, empleando distintas técnicas multivariantes, los patrones de diversidad y distribución de estos organismos. Los datos se tomaron de ejemplares capturados en lugares del medio terrestre próximos a la línea de costa, de la franja intermareal rocosa y de sedimentos de fondos marinos situados a 10 y 20 m de profundidad. Las especies fueron clasificadas atendiendo a la morfología y el tamaño, y se analizaron a nivel supraespecífico para elucidar los patrones generales, que se discuten aquí, brevemente, con especial énfasis en las diferencias según la importancia de los factores que controlan cada ecosistema, como, por ejemplo, los procesos de dispersión. Los resultados de los distintos sistemas se comparan y discuten en el contexto de las tendencias ecológicas y evolutivas de los moluscos., Instituto Español de Oceanografía

Molluscs are the second most diverse of all animal phyla, and occur in many habitat types. They are, therefore, a particularly good phylum with which to compare and contrast differences between ecosystems. Mollusc data from a number of sites along the southern coast of the Iberian Peninsula are analysed to study patterns of diversity and distribution using a range of multivariate techniques. Within each site, data are presented from three locations -fully terrestrial, rocky intertidal and soft bottom benthic (10 m and 20 m depths)- all in close proximity. The species are then classified in relation to morphology and size, and analysed at supraspecific levels to elucidate underlying patterns. The observed patterns are briefly discussed, with particular reference to the differential scope and importance of controlling factors in each ecosystem, such as dispersal processes. The results from the systems are compared and discussed in the context of ecological and evolutionary constraints in Mollusca Los moluscos constituyen el segundo filo animal más diverso y se encuentran en muchos tipos de hábitat, por lo que son idóneos para establecer comparaciones entre distintos ecosistemas. Se han analizado los datos de los moluscos obtenidos en una serie de emplazamientos que cubrían el sur de la península Ibérica para determinar, empleando distintas técnicas multivariantes, los patrones de diversidad y distribución de estos organismos. Los datos se tomaron de ejemplares capturados en lugares del medio terrestre próximos a la línea de costa, de la franja intermareal rocosa y de sedimentos de fondos marinos situados a 10 y 20 m de profundidad. Las especies fueron clasificadas atendiendo a la morfología y el tamaño, y se analizaron a nivel supraespecífico para elucidar los patrones generales, que se discuten aquí, brevemente, con especial énfasis en las diferencias según la importancia de los factores que controlan cada ecosistema, como, por ejemplo, los procesos de dispersión. Los resultados de los distintos sistemas se comparan y discuten en el contexto de las tendencias ecológicas y evolutivas de los moluscos

EC Directive 2000/60 of the European Parliament and of the Council of Europe provides for the need to establish ecological regions along European coasts. The present article outlines research carried out in various coastal marine ecosystems as a contribution to the characterization of these ecoregions of the coast of Andalusia (southern Spain). Sampling was undertaken along the coastline in the intertidal zone and sublittoral sediments. The various systems studied all gave very similar results with regard to the ecoregions identified, which is indicative of their robustness. These results consistently identified a main Mediterranean region, which could subsequently be subdivided into two, as well as three main ecoregions in the Atlantic: one from the Straits of Gibraltar to the Bay of Cadiz, and the other two along the Huelva coastline, which are clearly affected by the effluents of major river systems such as the Guadalquivir, Odiel and Tinto. Our results suggest that similar structuring factors are operating within these systems. La Directiva 2000/60 CE del Parlamento Europeo y del Consejo Europeo contempla la necesidad de establecer regiones ecológicas a lo largo del litoral europeo. Con el objetivo de contribuir a la delimitación y caracterización de estas ecorregiones se ha realizado este estudio de varios ecosistemas marinos centrado en el litoral andaluz (sur de España). Los muestreos se realizaron en la franja intermareal rocosa y en sedimentos infralitorales. Los sistemas estudiados dieron resultados similares con respecto a la definición de las distintas ecorregiones. Así, se identificó una gran área mediterránea, que podría dividirse en dos, y otra atlántica, que se divide en tres ecorregiones: una comprende desde el estrecho de Gibraltar hasta la bahía de Cádiz y otras dos emplazadas en el litoral de Huelva caracterizadas por la presencia de importantes efluentes fluviales como el Guadalquivir, el Odiel y el Tinto. Los resultados sugieren que existen factores estructurales similares en estos sistemas.