Alpheus cf. packardii Kingsley, 1880

Herrera-Barquín, Hiram, Leija-Tristán, Antonio & Favela-Lara, Susana, 2018, Updated checklist of estuarine caridean shrimps (Decapoda: Caridea) from the southern region of Laguna Madre, Tamaulipas, Mexico, with new records and a key for taxonomic identification, Check List 14 (2), pp. 479-494 : 484-486

Alpheus cf. packardii Kingsley, 1880

Figure 4D–F

Material examined (25 specimens) Among seagrass meadows, in shallow waters adjacent to deeper areas. 8 March 2014 (UANL-FCB-C19-8126), S2 (24°29.1833ʹ N, 097°41.9667ʹ W), 14 specimens (7♀, 7♂); 9 March 2014 (UANL-FCB-C19-8131), S3 (24°29.2667ʹ N, 097° 45.9833ʹ W), 11 specimens (4♀, 7♂).

Distribution. Western Atlantic: Bermuda; North Carolina to Florida; Gulf of Mexico; throughout the Caribbean Sea; Brazil ( Anker et al. 2016). In Mexico: Bahía de la Ascensión, Bahía del Espíritu Santo, Arrecife Mahahual ( Román-Contreras and Martínez-Mayén 2010); Isla Verde, Arrecife Hornos, Isla de Sacrificios, Isla de Enmedio, Veracruz ( Hermoso-Salazar and Arvizu-Coyotzi 2015); Laguna Madre, Tamaulipas (this study [new record]).

Previous records from Laguna Madre. None. New record.

Remarks. Kingsley (1878) described Alpheus normanni based on material from the Pacific coast of Panama. Two years later, he described A. packardii based on specimens from Key West, Florida ( Kingsley 1880). Chace (1937) considered both as identical morphologically, and placed A. packardii as a synonym of A. normanni . Several authors continued treating these species as synonyms or only reported A. normanni for the western Atlantic ( Williams 1965, Chace 1972, Christoffersen 1979, Williams 1984, Abele and Kim 1986, McClure 2005). Nevertheless, Kim and Abele (1988) compared material from the eastern Pacific and western Atlantic (Florida), and found consistent morphological differences in the form of the male minor chelae, being more elongated in the Pacific specimens (5.8 times as long as broad); thus, they removed A. packardii from the synonymy of A. normanni . The minor chelae of the males we examined ranges from 3.17–4.67 times as long as broad, which overlaps the range of 3.64–4.38 described by Román- Contreras and Martínez-Mayén (2010) as an argument to conclude their material belongs to A. packardii species complex. Moreover, our material is morphologically similar to specimens identified also as A. cf. packardii or A. packardii ( Soledade and Almeida 2013, Giraldes and Freire 2015, Anker et al. 2016, see figures). Additionally, according to Christoffersen (1998), the western Atlantic specimens previously named as A. normanni must be attributed to A. packardii .

Regardless the above, both species are part of the transisthmian A. normanni – A. packardii species complex that is currently being revised ( Anker et al. 2016, Anker and Santos unpubl.). Species complexes are relatively common within highly species-rich caridean taxa like the genus Alpheus , which comprises many species with very similar morphology, even in the presence of high genetic or protein divergence ( Knowlton et al. 1993, McClure and Greenbaum 1994, Knowlton and Weight 1998, Mathews et al. 2002). This has led to nomenclatural confusion, and the taxonomic identity of the western Atlantic material identified as A. normanni will need to be carefully reassessed since it is quite possible that it refers to more than 1 species ( Anker et al. 2016).

The presence of several cryptic taxa within the genus Alpheus from eastern Pacific and western Atlantic ( Williams et al. 2001), the molecular, morphological, coloration patterns and distributional evidence showing that A. normanni and A. packardii are different, as well as the existence of at least 5 undescribed cryptic species belonging to normanni – packardii complex (3 in western Atlantic and 2 in the eastern Pacific) ( Almeida et al. 2007, Román-Contreras and Martínez-Mayén 2010, Vera-Caripe et al. 2012, A. Anker pers. com.) makes the taxonomy unsettled for both, but the establishment ofseveral separate species is the likely outcome. Thus, in this work we identified the collected specimens as Alpheus cf. packardii for the aforesaid considerations, evidence and taxonomic issues, and because recent studies have used the name A. packardii for records from the Gulf of Mexico ( Román-Contreras and Martínez-Mayén 2010, Hermoso-Salazar and Arvizu-Coyotzi 2015), the Caribbean Sea ( Vera-Caripe et al. 2012) and Brazil ( Souza et al. 2011; Santos et al. 2012, Soledade and Almeida 2013 and all previous records mentioned there in, Giraldes and Freire 2015, Anker et al. 2016).