Caprella equilibra Say 1818
Creators: name: Paz-Ríos, Carlos E.
name: Guerra-García, José M.
name: Ardisson, Pedro-Luis
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Caprellidae
Caprella
Caprella equilibra

description: Caprella equilibra Say, 1818   
(Figure 2)  
 Caprella equilibra Say, 1818; Steinberg and Dougherty, 1957: 273–274, figs 1, 2. McCain, 1968: 25–30, figs 12, 13. McCain and Steinberg, 1970; Cavedini, 1982; Lazo-Wasem and Gable, 1987: 335–336, fig. 10. Krapp-Schickel, 1993: 782–783, fig. 533. Serejo, 1998; Ortiz et al., 2002, fig. 21. Foster, Thomas, et al., 2004: 162, 167–168, fig. 7. Diaz et al., 2005: 3–4, fig. 4. Winfield, Escobar-Briones, et al., 2007: 44, fig. 14. Guerra-García and Ros, 2012: 76–78, fig. 2.   
 Caprella aequilibra Mayer, 1882: 45, pl. 1, fig. 7, pl. 2, figs 1–11, pl. 4, figs 20–25, pl. 5, figs 16–18. Chevreux and Fage, 1925: 455, fig. 433.   
 Caprella bermudia Kunkel, 1910: 108–110, fig. 42. Lazo-Wasem and Gable, 1987: 335–336, fig. 10.    Material examined   
Station 33, two males, six females, two juveniles (one male and one female from this station used for figures), BRTC 2–9489.   Type locality   
Charleston, South Carolina.   Distribution   
Cosmopolitan (McCain 1968; Krapp-Schickel 1993).   Records in the Gulf of Mexico   
MEX: Tamaulipas and Veracruz continental shelf (Escobar-Briones and Winfield 2003); Mexican ridges and Sigsbee abyssal plain at southwest (Winfield et al. 2006). USA: Port Aransas (Steinberg and Dougherty 1957); Port Isabel; Galveston; Grand Isle; Panama City (McCain 1968); Louisiana Offshore (Lewbel et al. 1987); Coast of Mississippi; St Andrew Bay (Foster, Thomas, et al. 2004); Port Aransas Offshore (present study).   Habitat   
 Caprella equilibra has been found on seagrasses, green and red algae, sponges, hydroids, alcyonarians, bryozoans, gorgonians, and ascidians (McCain 1968; Gable and Lazo-Wasem 1987; Alarcón-Ortega et al. 2012). It has also been found in plankton samples, artificial substrata (Lewbel et al. 1987; Takeuchi and Sawamoto 1998; present study) and on the carapace of the loggerhead sea turtle Caretta caretta (Caine 1986). The depth range reported is shallow water extending to 3700 m (Winfield et al. 2006; Winfield and Escobar-Briones 2008; LeCroy et al. 2009).    Remarks   
 In the Gulf of Mexico, C. equilibra is similar to C. danilevskii because both lack a cephalic spine. However, these species can be easily separated because C. equilibra has a ventral spine between the bases of the second gnathopod, whereas C. danilevskii does not.   
 A recent morphological study of C. equilibra in southern Spain has revealed intraspecific variation in the female abdomen, even within the same population (Guerra-García and Ros 2012). According to the diagnosis of the genus Caprella by McCain (1968), the abdomen of males is provided with a pair of uni- or bi-articulate appendages and a pair of lobes; females only have the pair of lobes and lack appendages. However, a few females of C. equilibra found in southern Spain were provided with abdominal appendages. The study provided evidence supporting the idea that the abdominal appendage is a polymorphic and symplesiomorphic character in Caprella and Metacaprella Mayer, 1903 (another genus with the same morphological variation), and that Metacaprella is not a valid genus (Guerra-García and Ros 2012).
description: Published as part of Paz-Ríos, Carlos E., Guerra-García, José M. & Ardisson, Pedro-Luis, 2014, REVIEW ARTICLE Caprellids (Crustacea: Amphipoda) from the Gulf of Mexico, with observations on Deutella mayeri, redescription of Metaprotella hummelincki, a taxonomic key and zoogeographical comments, pp. 2517-2578 in Journal of Natural History 48 (41 - 42) on pages 2524-2526, DOI: 10.1080/00222933.2014.931481, http://zenodo.org/record/5194444