Distribution and species richness of caprellids (Crustacea: Amphipoda) from the Mexican Pacific

Abstract

Background

The caprellid fauna from different localities along the Mexican Pacific coast: Sinaloa (3), Nayarit (15), Jalisco (9) and Colima (1) are presented herein.

Methods

A total of 1,093 specimens associated with diverse substrates (octocorals, hydroids, algae, coral rubble and sponge) were recorded.

Results

Eight species in four genera were identified: Aciconula acanthosoma Chess 1989; Caprella mendax Mayer 1903; Caprella pitu Sánchez-Moyano, García-Ascencio and Guerra-García 2014; Caprella suprapiscis Galván-Villa and Ayón-Parente 2015; Paracaprella carballoi Sánchez-Moyano, García-Ascencio and Guerra-García 2014; Paracaprella isabelae Sánchez-Moyano, García-Ascencio and Guerra-García 2014; Paracaprella pusilla Mayer 1890; and Liropus isabelensis Sánchez-Moyano, García-Ascencio and Guerra-García 2014.

Conclusions

The new records increase the known species richness in the region at local level, including extensions of the known ranges for all the species. These results highlight the need for a large scale survey along the Mexican Pacific coast, along with a more thorough sampling on a large number of substrata, in order to increase the knowledge of caprellid diversity in the area.

Introduction

Caprellids are small crustaceans commonly known as “skeleton shrimps”, which are abundant and important members of the marine benthos, inhabiting a wide variety of substrates (e.g., bryozoans, macroalgae and sponge) as epibionts, with a high preference for hydroids and gorgonians in tropical regions (McCain, 1968; Guerra-García, 2006; Scinto et al., 2008; Alarcón-Ortega et al., 2012; Sánchez-Moyano et al., 2014; Soler-Hurtado and Guerra-García, 2016). They are also part of fouling communities (Thiel et al., 2003; Ros and Guerra-García, 2012; Alarcón-Ortega et al., 2015), and their distribution varies from intertidal to abyssal zones (Laubitz and Mills, 1972; Woods, 2009). They are fundamental in marine ecosystems as recyclers of organic matter and as an energy source at different trophic levels (Caine, 1989; Woods, 2009).

The caprellids from the Eastern Tropical Pacific (ETP) have been little studied. To date in this region a total of 16 species has been recorded: Aciconula acanthosoma Chess, 1989 from Mexico and Ecuador; Abbysicaprella galatheae McCain, 1966 from Costa Rica and Peru; Caprella ungulina Mayer, 1903 from Ecuador; C. californica Stimpson, 1856 from Mexico; C. equilibra Lamark, 1881 from Mexico, Panama and Ecuador; C. scaura Templeton, 1836 from Mexico and Costa Rica; C. mendax Mayer, 1903 from Mexico; Paracaprella banardi McCain, 1967 from Panama and P. pusilla Mayer, 1890 from Mexico and Panama (Mayer, 1903; Shoemaker, 1942; McCain, 1966; McCain, 1967; McCain and Steinberg, 1970; Laubitz, 1970; Alarcón-Ortega et al., 2012; Ros et al., 2014; Sánchez-Moyano et al., 2014; Soler-Hurtado and Guerra-García, 2016), plus recent descriptions, all from Mexico: C. calderoni Hendrickx and Ayón-Parente, 2014; C. mercedesae Hendrickx and Ayón-Parente, 2014; C.pitu Sánchez-Moyano et al., 2014; C. suprapiscis Galván-Villa and Ayón-Parente, 2015; Liropus isabelensis Sánchez-Moyano et al., 2014; P. carballoi Sánchez-Moyano et al., 2014 and P. isabelae Sánchez-Moyano et al., 2014 (Hendrickx and Ayón-Parente, 2014; Sánchez-Moyano et al., 2014; Galván-Villa and Ayón-Parente, 2015).

Despite the relevance of the distribution and richness of caprellid amphipods from the Mexican Pacific (MP) in particular Central Mexican Pacific (CMP) is almost unstudied and more information is required to fill the information gap. However, there are a few studies relating with the caprellid biota: Alarcón-Ortega et al. (2012) report for the first time a total of four species at six stations during 2011-2012 (A. acanthosoma, C. equilibra, C. aff. penantis and Paracaprella sp.) and describe the feeding habitats of caprellids in this area; Sánchez-Moyano et al. (2014) report three new records and four new species (A. acanthosoma, C. equilibra, C. mendax, C. pitu, P. carballoi, P. isabelae, L. isabelensis) from 10 stations during two expedition in 2002 and 2008; Alarcón-Ortega et al. (2015) report the presence of one non-indigenous species from four stations between 2013-2014; Galván-Villa and Ayón-Parente (2015) describe a new species, C. suprapiscis, associated with scorpionfish. At this point, the caprellid studies have only been focused at the small-scale level during short and sporadic surveys, generating a little information about caprellid species and their distribution. Therefore the aim of the present study was to update the information on the biodiversity of caprellids in the MP, performing a large latitudinal survey from 19°06′17″ N to 25°26′09″ N along the Central Mexican coast (843 km) and surrounding islands (20.68 km^-2), including range extensions and ecological data of four genera and eight caprellid species in order to broaden the records of the distribution of these amphipods in the ETP. These findings are important in documenting the extensions of the known ranges of the species, but also increase knowledge of the biodiversity of the entire region.

Material and methods

The Central Mexican Pacific is considered as a transitional oceanographic area, and is seasonally influenced by three important current systems: the California Current carrying cold (~18 °C), low-salinity and high-nutrient water (Kessler, 2006; Pennington et al., 2006; Pantoja et al., 2012); the Gulf of California Current carrying warm waters with high salinity; and the Mexican Coastal Current carrying warm (~30 °C), clear and low-nutrient water (Wyrtki, 1965; da Silva et al., 1994; Palacios-Hernández et al., 2010; Pantoja et al., 2012). These oceanographic conditions drive an inter-annual variability of environmental conditions, which may allow the presence of different species within the area.

The specimens reviewed were collected from 28 stations (St.) along Sinaloa (3), Nayarit (15), Jalisco (9) and Colima (1) coasts (Table 1, Fig. 1) from September 2012 to June 2016. Samples were obtained by SCUBA diving, by scraping diverse substrates (e.g. algae, hydroids, hydrocorals, sand, sponge, coral rubble, turf and artificial material) from depths between 1 to 25 m into plastic bags. In the laboratory caprellids were separated using a Carl Zeiss Stemi DV4 stereoscopic microscope, examined under an Olympus optical microscope and preserved in 70% ethanol. The organisms were identified using specialized literature (Mayer, 1903; McCain, 1968; Chess, 1989; Laubitz, 1970; Sánchez-Moyano et al., 2014; Galván-Villa and Ayón-Parente, 2015). The classification system was based on that proposed by Myers and Lowry (2003) considering the Superfamily Caprelloidea, Family Caprellidae and Subfamily Caprellinae. Token specimens were deposited in the Laboratorio de Ecología Marina del Centro de Investigaciones Costeras, Centro Universitario de la Costa, Universidad de Guadalajara, México and Regional Collection of Marine Invertebrates, (ICML-EMU) at the Instituto de Ciencias del Mar y Limnología, UNAM, in Mazatlán, México. Abbreviations used for the collectors were: ATL; Adolfo Tortolero Langarica; KR, Karla Ríos; LCAO, Lucy Coral Alarcón Ortega and RSC, Rosa Sotelo Casas.

Table 1 Locality and geographic coordinates of the sampling sites in the Mexican Pacific

Fig. 1

Map of the study area with sampling localities (black circles) where caprellid species were collected. For localities see Table 1

Results

A total of eight species of caprellids were documented.

Systematic account

Family Caprellidae Leach, 1814

Subfamily Caprellinae Leach, 1814

Genus Aciconula Mayer, 1903

Aciconula acanthosoma Chess, 1989

Aciconula acanthosoma Chess, 1989: 662–665, figs. 1–2. Sánchez-Moyano et al., 2014: 82, fig. 2. Soler-Hurtado and Guerra-García, 2016: 1–17, figs. 3–5.

Type locality: Santa Catalina Island, California

Distribution: USA: Santa Catalina Island, California (Chess, 1989). Mexico: Isla de los Pájaros and Isla Venado, Mazatlán, Sinaloa; Bahía Tiburón, Cerro Pelón and las Monas, Isla Isabel, Nayarit (Alarcón-Ortega et al., 2012; Sánchez-Moyano et al., 2014). Ecuador: Machalilla National Park, Manabí (Soler-Hurtado and Guerra-García, 2016).

Material examined: St. CB: 17 November 2015, on hydroids, 5 m depth, coll. LCAO, 1♀, 1♂ and 2 juveniles. St. RE: 17 November 2015, on hydroids, 7 m depth, coll. LCAO, 6♀, 3♂ and 8 juveniles. St. CLI: 15 September 2015, on green algae, at 7 m depth, coll. ATL, 1 juvenile. St. BV: 25 March 2013, on turf, at 9 m, coll. LCAO, 1♀, 1♂ and 2 juveniles. St. CM: 14 January 2014, on turf, 6 m depth, coll. LCAO, 1♂ and 2 juveniles. St. ZR: 07 May 2013, collected from algae Halimeda discoidea, at 2 m coll. LCAO, 1♀. St. ZRS: 7 November 2013, on coral rubble, at 6 m depth, coll. LCAO, 1♀; 14 January 2014, on sponge, at 7 m depth, coll. LCAO, 1♀. St. PP: 22 January 2013, on turf, at 11 m depth, coll. LCAO, 1 ♀; 5 November 2013, on turf at 6 m depth, coll. LCAO, 1♀, 1♀; 22 February 2014, on encrusting coral Porites panamensis with epiphytic hydroids, at 6–12 m depth, coll. ATL, 2♀, 4♂, and 3 juveniles, (ICML-EMU 11786). St. TA: 28 January 2013, on turf, at 13 m depth, 1♀, 1♂; 15 January 2014, on sponge, at 7 m depth, coll. LCAO, 1♀, 2♂ and 2 juveniles. St. PA: 25 January 2013, on turf, at 6 m depth, coll. LCAO, 1♀, 2 juveniles; 15 January 2014, on turf, at 5.7 m depth, coll. LCAO, 1♀, 1♂. St. AR: 30 March 2014, on hydroids, 24 m depth, coll. LCAO, 1♀ and 2 juvenile; 30 March 2014, on algae Padina sp., 9 m depth, 8♀, 9♂ and 14 juveniles. St. MI: 20 September 2012, on hydroids, 6.40 m depth, coll. LCAO, 5♀, 5♂ and 5 juveniles (Fig. 2).

Fig. 2

Map of Aciconula acanthosoma distribution records along the Mexican Pacific coast. Localities: CL, Cueva del Lobo; RE, Los Relices; IP, Isla de los Pájaros; IV, Isla Venados; II, Isla Isabel; CP, Cerro Pelón; LM, Las Monas; BT, Bahía Tiburón; CLI, Cleofas I; BB, Bahía de Banderas; MA, Islas Marietas; CM, Cueva del Muerto; ZRS, Zona de Restauración Sur; ZR, Zona de Restauración, TA, Túnel Amarradero; PP, Plataforma Pavonas; PA, Playa del Amor; AR, Los Arcos; MI, Mismaloya. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Diagnosis: Body length range 2.73–6.42 mm for males, and 2.6–4.86 mm for females. Body dorsally covered with acute spines. Head provided with four curved spines. Basis of gnathopod 2 provided with acute lateral projection. Gnathopod 2, palmar surface of propodus fitted with two distal triangular projections and mid excavation bordered proximally by strong spine, proximal surface with row of fine blunt serrations and single grasping spine. Pereopods 3 and 4 reduced with two articles. Pereopod 5 lacking grasping structures (typical of genus) (Chess, 1989).

Ecology: Aciconula acanthosoma was present on coral rubble, hydroids, macroalgae, gorgonians and sponge being more abundant in turf, whilst Sánchez-Moyano et al. (2014) reported specimens were more abundant in sessile organisms (hydroids, gorgonians and bryozoans). The body is generally brown and covered with detritus mainly pereonite 5, and animals were observed feeding on this detritus with their first gnathopods. The principal dietary component of A. acanthosoma from the study area is mainly detritus, crustaceans and hydroids (Alarcón-Ortega et al., 2012). A. acanthosoma also is a dietary component of many fish species from the families Cottidae, Embiotocidae, Pomacentridae, Labridae, Labrisomidae, and Gobiidae (Chess, 1989). The species’ abundance underwent seasonal variations, with higher numbers observed during the winter season, a similar pattern as reported by Chess (1989) and Soler-Hurtado and Guerra-García (2016).

Caprella mendax Mayer, 1903

Caprella mendax Mayer, 1903, 114, pl. 5, fig. 9, 10, 11, pl. 8, 22. Laubitz, 1970: 59, fig. 18; Sánchez-Moyano et al., 2014: 89–93, figs. 6–8.

Examined material: St. CO: 13 October 2013, on gorgonians Leptogorgia rigida, 8 m depth, coll. LCAO, 13♀, 9♂, and 6 juveniles. St. PM: October 2013, on algae Caulerpa sp., 2 m depth, coll. LCAO, 1♂. St. PP: 19 March 2013, on hydroids Lytocarpus nuttingui, at 5 m depth, coll. LCAO, 7♀, 14♂ and 7 juveniles (IMCL-EMU 11787 B). St. BV: 06 February 2014, on L. nuttingui, at 9 m depth, coll. LCAO, 12♀, 15♂ and 6 juveniles (ICML-EMU 11787 A). St. AR: 30 March 2014, on hydroids, 24 m depth, coll. LCAO, 6♀, 10♂ and 5 juveniles; 20 September 2012, on hydroids, 6 m depth, coll. LCAO, 4♀, 4♂ and 3 juveniles. St. MI: 20 September 2012, on hydroids, 6 m depth, coll. LCAO, 4♀, 4♂ and 3 juveniles. St. COL: 09 June 2014, on hydroids, 11 m depth, coll. ATL, 2♀, 2♂. St. CH: 16 August 2014, on hydroids, 14 m depth, coll. LCAO, 11♀, 7♂ and 19 juveniles. St. AS: 28 April 2015, on hydroids and L. rigida, 6 m depth, coll. ATL, 14♀, 6♂ and 37 juveniles. St. BO: 10 December 2013, on hydroids, 2 m depth, coll. LCAO, 2♀, 2♂ and 2 juveniles (Fig. 3).

Fig. 3

Map of Caprella mendax distribution records along the Mexican Pacific coast. Localities: MZ, Mazatlán; IP, Isla de los Pajáros; IV, Isla Venado; EU, Estero Urías; CO, Corbeteña; PM, Punta de Mita; PP, Plataforma Pavonas; BV, Bajo Viudas; AR, Los Arcos; MI, Mismaloya; CH, Chimo; AS, Arroyo Seco; BO, La Boquita. Gray star = Syntype; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: California (the type locality was not specified, but the species was collected in Pacific Grove, Santa Barbara and San Diego).

Distribution: Canada: Vancouver Island and Strait of Hécate, British Columbia; San Juan Island, Washington (Laubitz, 1970; Caine, 1977), Humboldt Bay (Martin, 1977). USA: Dillon Beach, Moss Beach and Pacific Grove-Monterrey Bay, California (Dougherty and Steinberg, 1953); Santa Barbara, San Diego, California (Laubitz, 1970). Mexico: Isla de los Pájaros, Isla Venado and Estero de Urías in Mazatlán, Sinaloa (Sánchez-Moyano et al., 2014).

Diagnosis: Body length range 5.40–18.82 mm for males, 2.72–11.62 mm for females. Head without projections, body smooth with a small projection at the base of the second gnathopods. Antenna 1 longer than the pereonite 1, 2 and 3 combined with 16 articles in flagellum. Antenna 2 with abundant swimming setae. Ventral spine between the bases of Gnathopod 2 absent. Gnathopod 2, propodus with a proximal grasping spine with a small accessory spine and triangular projection distally. Basis of gnathopod 2 with an anterior denticulate carina. Gills present on pereonite 3 and 4, elliptical. Pereopods 5, 6 and 7 increasing in length, with propodus with proximal grasping spines and concave palm (Laubitz, 1970; Sánchez-Moyano et al., 2014).

Ecology: Caprella mendax has been collected from many substrates such as kelp forest, sand, boulders and hydroids from the intertidal zone to 80 m deep (Caine, 1977; Martin, 1977; Hammer and Zimmerman, 1979). C. mendax was the most abundant species collected in the study area, presenting high densities (7,297 ind.m^-2) on the hydroid L. nuttingi in the cold season, moreover, this species has been observed on seaweeds with epiphytic hydroids and on gorgonians (Sánchez-Moyano et al., 2014).

Caprella pitu Sánchez-Moyano et al., 2014

Caprella pitu Sánchez-Moyano et al., 2014: 17–26, figs. 9–14.

Material examined: St. PO: 16 August 2013, on gorgonian L. rigida, 2 m depth, coll. LCAO, 2♀ and 18 juveniles. St. JP: 26 April 2016, on L. rigida, 24 m depth, coll. LCAO, 1♂. St. CLII: 02 June 2016, on Leptogorgia sp., at 9 m depth, coll. ATL, 4♀. St. CO: 13 October 2013, on gorgonians L. rigida, 8 m depth, coll. LCAO, 5♀, 6 juveniles. St. CM: 07 November 2013, on L. rigida, at 4.87 m depth, coll. LCAO, 2♀, 1♂ and 8 juveniles. St. ZR: 07 November 2013, on L. rigida, at 2 m depth, coll. LCAO, 4♀, 2♂. St. ZRS: 7 November 2013, on L. rigida, at 5 m depth, coll. LCAO, 1♀ and 2 juveniles. St. PP: 22 January 2013, on L. rigida at 9 m, coll. LCAO, 1♀. St. TA: 08 May 2013, on L. rigida at 6 m depth, coll. LCAO, 10♀, 6♂. St. PA: 25 January 2013, on L. rigida, at 7 m depth, coll. LCAO, 1♀. St. BV: 28,May 2013, on gorgonian L. cuspidata, at 7 m depth, coll. LCAO, 11♀, 11♂ and 9 juveniles (ICML-EMU 11788 A); 12 November 2013, on L. rigida, at 5.5 m depth, coll. LCAO, 3♀, 2♂ and 3 juveniles. St. AR: 30 March 2014, on L. rigida, 24 m depth, coll. LCAO, 12♀, 4♂ and 46 juveniles. St. MI: 30 March 2014, on gorgonians L. rigida, 2 m depth, coll. LCAO, 12♀, 2♂ and 45 juveniles (ICML-EMU 11788B). St. CH: 16 August 2014, on L. rigida, 14 m depth, coll. ATL, 2♀ and 13 juveniles. St. AS: 28 April 2015, on L. rigida, 6 m depth, coll. ATL, 23♀, 7♂ and 126 juveniles. St. CUA: 11 December 2013, on Leptogorgia sp., 3 m depth, coll. LCAO, 10♀, 2♂ and 10 juveniles. St. LAB: 12 December 2013, on L. cuspidata, 3 m depth, coll. LCAO, 27 ♀, 22♂ and 19 juveniles (Fig. 4).

Fig. 4

Map of Caprella pitu distribution records along the Mexican Pacific coast. Localities: IV, Isla Venado; II, Isla Isabel; CP, Cerro Pelón; LM, Las Monas; PO, Pocitas; MA, Islas Marias; BB, Bahía de Banderas; CO, Corbeteña; MA, Islas Marietas; CM, Cueva del Muerto; ZRS, Zona de Restauración Sur; ZR, Zona de Restauración; TA, Túnel Amarradero; PP, Plataforma Pavonas; PA, Playa del Amor; BV, Bajo Viudas; AR, Los Arcos; MI, Mismaloya; CH, Chimo; AS, Arroyo Seco; CU, Cuastecomatitos; LAB, Laboratorio 1. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: Isla de los Pájaros, Mazatlán, Mexico (Fig. 4).

Distribution: Mexico: Isla de los Pájaros and Isla Venado, Mazatlán, Sinaloa; Las Monas in Isla Isabel and Islas Marietas, Nayarit; Los Arcos, Jalisco (Sánchez-Moyano et al., 2014).

Diagnosis: Body length range 3.07–5.52 mm for males and 2.03–3.978 mm for females. Head provided with a short, triangular projection. Body stout and wide with tiny tubercles; in dorsal view, body wide, with lateral and flat expansion mainly in pereonites 3 and 4. Peduncle of antenna 1 scarcely setose. Gnathopod 2 basis short with an anterior carina; palm of propodus with an acute projection medially and a rounded distal one. Pereiopods 3 and 4 absent. Gills rounded. Pereiopods 5–7 robust and increasing in length; carpus elongate and palm of propodus without grasping spines; dactylus short and robust (Sánchez-Moyano et al., 2014).

Ecology: Caprella pitu has been found on different species of gorgonians (Leptogorgia sp., L. rigida, L. peruviana, L. alba, Pacifigorgia sp. and P. cf. agassizzi), and was abundant in L. rigida between 2–25 m depth in coral reef areas (Sánchez-Moyano et al., 2014, present study). Moreover, C. pitu, shared its habitat with numerous brittle stars [Ophiactis simplex, Ophiothela mirabilis, Ophiothrix (Ophiothrix) spiculata, O. (Ophiothrix) rudis], mainly in BV. This species shows body pigmentation related to the coloration of the substrate they are sheltering in (clear with pink spots, purple or dark brown with yellow spots), possibly to avoid detection by predators.

Caprella suprapiscis Galván-Villa and Ayón-Parente, 2015

Caprella suprapiscis Galván-Villa and Ayón-Parente, 2015: 572–576, figs. 2–6.

Examined Material: St. BV: 25 March 2013, collected from gorgonian Leptogorgia alba, at 7 m depth, 4♀, 6♂ and 3 juveniles. 06 January 2014, from L. alba, at 8 m depth, 8♀, 9♂ and 10 juveniles, (ICML-EMU 11789) (Fig. 5).

Fig. 5

Map of Caprella suprapiscis distribution records along the Mexican Pacific coast, and previous records in the area. PAJ, La Pajarera; COL, Colorado; SA, San Agustín; BV, Bajo de las Viudas. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: Isla Cocinas, Bahía Chamela, Jalisco, Mexico (Fig. 5).

Distribution: Mexico: Isla Cocinas, Isla Pajarera, Isla Colorada, and San Agustín in Bahía de Chamela, Jalisco (Galván-Villa and Ayón-Parente, 2015).

Diagnosis: Body length between 4.04–9.95 mm for males, 4.08–6.65 mm for females. Body slender and smooth except for the dorsal cephalic projection. Antenna 1 about half of the body length, peduncle scarcely setose. Propodus of gnathopod 2 elongate, length about 3 times width, dorsal surface slightly convex, dorsal and ventral margins finely setose, with one proximal projection provided with a robust seta 2/5 from proximal end of ventral margin palm; another projection in the middle, followed by “U” notch distally; dactylus falcate, setose on dorsal and lateral margins. Pereopods 3 and 4 absent, 5–7 increasing in length, scarcely setose (Galván-Villa and Ayón-Parente, 2015).

Ecology: Caprella suprapiscis has been reported living on the body of the fish Scorpaena mystes, associated with coral and rocky reefs between 5–7 m depth (Galván-Villa and Ayón-Parente, 2015). In the study area C. suprapiscis was found only on the octocoral Leptogorgia alba, sharing habitat with numerous brittle stars such as O. (Ophiothrix) spiculata, O. simplex, O. (Ophiothrix) rudis and O. mirabilis and also others caprellids (C. mendax, A. acanthosoma and P. isabelae), isopods and gastropods at 4.5–11 m depth. The body color differs according to the substrate (Galván-Villa and Ayón-Parente, 2015); in the area, C. suprapiscis body pigmentation was clear with pink spots.

Genus Liropus Mayer, 1890

Liropus isabelensis Sánchez-Moyano et al., 2014

Sánchez-Moyano et al., 2014: 26–32, figs. 15–18.

Material Examined: CM: 14 January 2014, on turf, at 7 m depth, coll. LCAO, 3♀, 3♂, (ICML-EMU 11790). ZR: 07 May 2013, on coral rubble, at 3.90 m depth, coll. LCAO, 3♀, 5♂; 03 September 2013, on algae Halimeda discoidea at 1.8, depth, coll. LCAO, 2♀, 5♂. ZRS: 10 July 2013, on coral rubble at 4.6 m depth, coll. LCAO, 5♀, 3♂, 6 juveniles. PP: 08 May 2013, on coral rubble at 9 m depth, coll. LCAO, 1♀, 2♂. TA: 08 May 2013, on coral rubble, at 12 m depth, coll. LCAO, 4♀, 4♂. PA: 19 March 2013, on turf, at 3 m depth, coll. LCAO, 1♀, 5♂ and 2 juveniles (Fig. 6).

Fig. 6

Map of Liropus isabelensis distribution records along the Mexican Pacific coast, and the previous records in the area. IP, Isla de los Pájaros; II, Isla Isabel; BT, Bahía Tiburón; MA, Islas Marietas; BT, Bahía Tiburón; CM, Cueva del Muerto; ZRS, Zona de Restauración Sur; ZR, Zona de Restauración; TA, Túnel Amarradero; PP, Plataforma Pavonas; PA, Playa del Amor. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: Cerro Pelón, Isla Isabel, Nayarit, Mexico (Fig. 6).

Distribution: Mexico: Isla de los Pajáros, Mazatlán, Sinaloa; Bahía Tiburón, Isla Isabel, Nayarit.

Diagnosis: Body length range 1.94–2.27 mm for males, and 1.48–1.98 mm for females. Head rounded without projections; eyes present. Body dorsally smooth. Anterolateral acute and downward-directed projections on pereonite 2 and mediolateral projections on pereonite 3 in males. Flagellum of antenna 1 five-articulate. Gnathopod 2 basis slightly longer than pereonite 2; ischium and propodus elongate. Pereopods 3, 4 and 5 one-articulate. Abdomen without appendages in males (Sánchez-Moyano et al., 2014).

Ecology: Liropus isabelensis has been found on hydroids, gorgonians, bryozoans and seaweed with epiphytic hydroids (Sánchez-Moyano et al., 2014). This species was abundant mainly on coral rubble Pocillopora spp. and calcareous macroalgae H. discoidea but was also collected in turf and sponge, mainly associated with shallow water in coral reef ecosystems.

Genus Paracaprella Mayer, 1890

Paracaprella carballoi Sánchez-Moyano et al., 2014

Sánchez-Moyano et al., 2014: 32–39, figs. 19–22.

Material examined: St. PM: 06 July 2015, on algae Padina sp. with epiphyte hydroids, 3 m depth, coll. LCAO, 4♀, 5♂ and 3 juveniles, (ICML-EMU 11791). St. ZRS: 7 May 2013, on algae H. discoidea, at 3.9 m depth, coll. LCAO, 1♀, 3♂. St. ZR: 07 May 2013, on algae H. discoidea, 4.9 m depth, 1♀, 2♂ (Fig. 7).

Fig. 7

Map of Paracaprella carballoi distribution records along the Mexican Pacific coast. Localities: PM, Punta de Mita; IM, Islas Marietas; ZRS, Zona de Restauración Sur; ZR, Zona de Restauración. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: Isla de los Pájaros, Mazatlán, Mexico (Fig. 7).

Distribution: Only known from type locality.

Diagnosis: Body length range 2.53–4.31 mm for males, and 2.24–3.19 mm for females. Head rounded. Body dorsally smooth, except pereonite 2 with a rounded and narrow anterolateral projection (only in males). Flagellum of antenna 1 nine-articulate; peduncle scarcely setose. Antenna 2 a little shorter than the peduncle of antenna 1, swimming setae absent. Basis of gnathopod 2 with two distal short processes on lateral margin. Propodus of gnathopod 2 palm with rectangular projection proximally, carrying two proximal grasping spines and a distal robust tooth. Pereopods 3 and 4 two-articulate. Pereopods 5–7 without grasping spines. Abdomen with a pair of setose uni-articulate appendages (Sánchez-Moyano et al., 2014).

Ecology: A few specimens of P. carballoi were collected on algae Padina sp. and H. discoidea associated with coral reef ecosystems in two stations (ZR and ZRS) of this study. Moreover, the species has been found on octocorals Leptogorgia rigida and on seaweed Zoonaria cf. farlowii with small hydroids (Sánchez-Moyano et al., 2014).

Paracaprella isabelae Sánchez-Moyano et al., 2014

Sánchez-Moyano et al., 2014: 39–48, figs. 23–26.

Examined material: St. CLII: 02 June 2016, on hydroid, at 9 m depth, coll. ATL, 1♂. St. CM: 25 January 2013, on hydroids, 4 m depth, coll. LCAO, 1♀, 1♂; 14 January 2014, on algae H. discoidea, 4 m depth, coll. LCAO, 1♀, 1♂. St. ZR: 14 March 2013, on H. discoidea, at 2.13 m depth, coll. LCAO, 1♂. St. ZRS: 14 March 2013, on hydroid, at 4.5 m depth, coll. LCAO, 1♂. St. PP: 15 January 2014, on hydroids L. nuttingi, at 8 m depth, coll. LCAO, 1♀, 2♂. St. TA: 15 January 2014, on sponge Aplysina gerarodegreeni, at 5 m depth, coll. LCAO, 2 ♂. St. PA: 19 March 2013, on turf, at 8 m depth, coll. LCAO, 1♀, 2♂. St. BV: 28 May 2013, on sponge, at 7 m depth, coll. LCAO, 6♀, 6♂, (ICML-EMU 11792). St. CH: 16 August 2014, on hydroids, 14 m depth, coll. LCAO, 5♀, 2♂ and 7 juveniles. St. AS: 28 April 2015, on hydroids and L. rigida, 6 m depth, coll. ATL, 3♀, 1♂ and 1 juvenile. St. CU: 11 December 2013, on hydroids, 3 m depth, coll. LCAO, 1♂. St. LAB: 10 December 2013, on hydroids, 2 m depth, coll. LCAO, 1♂. St. BO10 December 2013, on hydroids, 2 m depth, coll. LCAO, 3♀, 4♂ (Fig. 8).

Fig. 8

Map of Paracaprella isabelae distribution records along the Mexican Pacific coast. Localities: II, Isla Isabel; CP, Cerro Pelón; BT, Bahía Tiburón; MA; Islas Marietas; CM, Cueva del Muerto; ZRS, Zona de Restauración Sur; ZR, Zona de Restauración; TA, Túnel Amarradero; PP, Plataforma Pavonas; PA, Playa del Amor; CSJ, Costa Sur de Jalisco; AS, Arroyo Seco; CU, Cuastecomates; LAB, Laboratorio 1; BO, La Boquita. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: Las Monas, Isla Isabel, Nayarit, Mexico (Fig. 8).

Distribution: Mexico: Cerro Pelón and Bahía Tiburón, Isla Isabel, Nayarit.

Diagnosis: Body length range 3.08–7.86 mm for males, and 2.31–5.15 mm for females. 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 forward-directed projection between the gnathopods 2. Propodus palm of gnathopod 2 with rectangular projection proximally, bearing one proximal grasping spine and a distal long robust tooth in males. Pereopods 3 and 4 two-articulate. Pereopods 5–7 without grasping spines. Abdomen with a pair of setose uni-aticulate appendages in male (Sánchez-Moyano et al., 2014).

Ecology: Paracaprella isabelae does not present specific substrate preferences because the species was collected from different substrates such as hydroids, bryozoans (Bugula sp.), sponge, fishing net, turf, algae (H. discoidea and Padina sp.), gorgonians (Leptogorgia spp. and M. austera) and coral rubble (Pocillopora spp.), distributed on a depth range of 2–25 m depth, a similar pattern to that reported by Sánchez-Moyano et al. (2014). The feeding behavior of this genus is mainly scraping and predation, eating detritus and crustaceans, grasping inorganic materials from the substrata (Caine, 1974; Alarcón-Ortega et al., 2012).

Paracaprella pusilla Mayer, 1890

Paracaprella pusilla Mayer, 1903: 41, pl. 1, figs. 28–30; pl. 2 36, 37; figs. pl. 3, figs. 45–47; pl. 5; figs. 48,49; pl. 6, fig. 10; 1903: 67; pl. 7, fig. 52. Edmonson and Mansfield 1948: 208–2010, fig. 4. Steinberg and Dougherty, 1957: 283–284, figs. 16, 19, 24, 30. McCain, 1968: 82–86, figs. 41–42. Serejo, 1998: 381, fig. 7j, l. Ortiz et al. 2002: fig. 37. Foster 2004: 165, fig. 5a–f. Díaz et al., 2005: 3, 6–7, fig. 13. Guerra-García et al. 2006: 175–178, figs. 17–19. Krapp-Schickel et al. 2006: 175–178, figs 17–19. Escobar-Briones et al. 2007: 30, 47, 49, fig. 16. Bhave and Deshmukh, 2009: 112, figs. 1–2. Guerra-García et al. 2010: 304–305, fig. 8. Ros et al. 2013: 71, fig. 2. Alarcón-Ortega et al., 2015: 213, fig. 2.

Caprella nigra Reid 1951: 283–284, 289, fig. 58.

Examined material: St. MM: 04 December 2013, on red algae, >1 m depth, coll ATL, 1♀, 1♂. St. MS: 16 October 2013, on hydroid, at >1 m depth, coll. ATL, 4♀, 5♂ (ICML-EMU 11039 A); 21 November 2013, on sponge, at >1 m depth, coll. LCAO, 4♀, 4♂ (ICML-EMU 11039 B). St. NV: 03 June 2013, on hydroid, at >1 m, coll. LCAO, 1♀, 1♂ (ICML-EMU 11040 B); 21 July 2013, on bryozoans, >1 m depth, coll. LCAO, 1♀, 1♂. St. ME: 26 March 2014, associated with oyster farm on macroalge Enteromorpha sp., >1 m depth coll. KR, 2♀, 3♂ (ICML-EMU 11040 A) (Fig. 9).

Fig. 9

Map of Paracaprella pusilla distribution records along the Mexican Pacific coast. Localities: MM, Marina Mazatlan; SB, San Blas; NV, Nuevo Vallarta; ME, Melaque. Filled star = type locality; gray circles = previous records from the Mexican Pacific; filled circle = new record

Type locality: Rio de Janeiro, Brazil (Fig. 9).

Distribution: Mexico: Sinaloa, Nayarit and Jalisco (Alarcón-Ortega et al., 2015). Panama: Panama Canal (Ros et al., 2014). See Ros and Guerra-García (2012); Ros et al. (2014).

Diagnosis: Head without projections; smooth body with a large anterolateral projection on pereonite 2; presence of a small dorsal tubercle on pereonite 2. Peduncle of antenna 1 setose and usually longer than antenna 2. Antenna 2 without swimming setae but densely setose. Propodus of gnathopod 1 with one proximal grasping spine; basis of gnathopod 2 with a proximal knob and propodus with trapezoidal projection on the inner margin.

Ecology: Paracaprella pusilla has been collected from mangrove roots, seagrasses, hydroids, ascidians, bryozoans, sponge, gravel bottoms, ropes, mussels and oysters mainly associated with fouling communities such as docks, floating pontoon, ballast water (McCain, 1968; Caine, 1978; Díaz et al., 2005; Bhave and Deshmukh, 2009; Ros et al., 2014; Alarcón-Ortega et al., 2015). The feeding strategy of P. pusilla is a carnivorous one, and its diet consists mainly of crustaceans, detritus and hydroids; moreover, its feeding strategies may change between natural and artificial habitats (Ros et al., 2014).

Conclusion

The present study includes new distribution records of eight caprellid species, mainly associated with coral reef ecosystems in different localities along 840 km of the Mexican Pacific coastal region (Figs. 2, 3, 4, 5, 6, 7, 8 and 9; Table 2). These reports increase the species richness in the region: three species were added for Nayarit (C. suprapiscis, C. mendax, and P. carballoi), three from Jalisco (P. isabelae, A. acanthosoma, and C. mendax) and one from Colima (P. isabelae).

Table 2 Extension of known ranges (Km) of caprellid species from the Mexican Pacific

At the species level, we highlight the invasive species Paracaprella pusilla which presents a notably isjunct distribution in the northern tropical east Pacific (Fig. 9; Table 2). The vector of introduction of this species in the area is still unknown (Ros et al., 2014). Documenting the extent of invasive non-native species is important because they may constitute threats to the local native fauna. We also highlight the substantial southward extension of C. mendax, which has been previously reported in Mexico only from Mazatlán, Sinaloa. Other important records relate to A. acanthosoma, which seems to have wide distribution throughout the Southern California to the Tropical East Pacific (Chess 1987; Alarcón-Ortega et al., 2012; Sánchez-Moyano et al., 2014; Soler-Hurtado and Guerra-García, 2016). C. suprapiscis (Isla Cocinas, Jalisco) and P. carballoi (Isla de los Pájaros, Sinaloa) were previously only recorded from their type localities associated with coral communities; the records presented here expand their known distributions northward and southward, respectively (Figs. 5 and 7; Table 2). It is possible that these species present strong affinities to coral communities. The results of this study highlight the importance of reef ecosystems for caprellid diversity, potentially due to the provision of numerous microhabitats (including hydroids, algae, octocorals and coral rubble) which may promote species diversity (Guerra-García, 2006; Kramer et al., 2014). At this point, the caprellid biota is commonly distributed along the Mexican coast and probably the distributions of the species recorded may extend beyond this area. Therefore, an intensive sampling effort in a wide variety of substrates and habitats along the entire ETP is recommended in order to determine species richness, diversity and potential caprellid community distribution zones over the Pacific Ocean.