Description of two new associateD infaunal DecapoD crustaceans

Two new species of infaunal decapod crustaceans are described based on material collected in Bahía Málaga, Pacific coast of Colombia, in 2009. The mud-shrimp Axianassa darrylfelderi sp. nov. (Axianassidae) appears to be most closely related to A. australis Rodrigues & Shimizu, 1992, A. canalis Kensley & Heard, 1990, and A. jamaicensis Kensley & Heard, 1990. The new species may be distinguished from each of them by a combination of morphological features, mainly on the uropodal exopod, antennal acicle, third maxilliped and first pleonite. The shrimp Leptalpheus canterakintzi sp. nov. (Alpheidae), associated with burrows of A. darrylfelderi sp. nov., undoubtedly represents the eastern Pacific sister species of the western Atlantic L. axianassae Dworschak & Coelho, 1999, which lives exclusively in burrows of A. australis. The two species are reliably distinguishable only by the proportions of the merus and propodus of the third pereiopod. Leptalpheus azuero Anker, 2011, previously known only from the Pacific coast of Panama, is reported for the first time from Bahía Málaga, Colombia. Key-Words: Decapoda; Shrimp; Mud-shrimp; Infauna; Symbiosis; Axianassidae; Alpheidae; Axianassa; Leptalpheus; Transisthmian species; East Pacific; New species; New record. However, most species have been collected on intertidal mud and sand flats, often close to mangrove stands, or in siltier parts of backreef lagoons. The alpheid shrimp genus Leptalpheus Williams, 1965 currently contains the highest number of infaunal symbiotic species in the family (14), the majority of them (11) distributed in very shallow tropical and subtropical parts of the western Atlantic and eastern Pacific (Williams, 1965; Ríos & Carvacho, 1983; Dworschak & Coelho, 1999; Anker et al., 2006a, 2008, 2011b; Salgado-Barragán et al., 2014), the remaining found in the tropical Indo-West Pacific INtrODUctION The mud-shrimp genus Axianassa Schmitt, 1924 in the monogeneric family Axianassidae currently includes 10 species, four in the western Atlantic (Schmitt, 1924; Kensley & Heard, 1990; Rodrigues & Shimizu, 1992), two in the eastern Pacific (Kensley & Heard, 1990), and four in the Indo-West Pacific (Anker, 2010, 2011a; Liu & Liu, 2010; Komai, 2014). All species of Axianassa inhabit coastal waters, burrowing in silt-sand or mud substrates in various intertidal and subtidal habitats, down to about 42 m. http://dx.doi.org/10.1590/0031-1049.2015.55.08 Volume 55(8):115‐129, 2015 1. Laboratório de Carcinologia, Museu de Zoologia, Universidade de São Paulo. Caixa Postal 42.494, 04218-970, São Paulo, SP, Brasil. E-mail: [email protected] 2. Grupo de Investigación en Ecología de Estuarios y Manglares, Departamento de Biología, Universidad del Valle, A.A. 25360 Cali, Colombia. Email: [email protected] (Banner & Banner, 1974; Anker & Marin, 2009). All members of this genus appear to be associated with burrowing ghost and mud shrimps (Callianassidae, Upogebiidae, Axianassidae), although for several species the actual hosts remain unknown. One species, Leptalpheus axianassae Dworschak & Coelho, 1999, appears to be associated exclusively with burrows of Axianassa australis Rodrigues & Shimuzu, 1992, in the western Atlantic from Florida to Brazil (Dworschak & Coelho, 1999; Felder et al., 2003). Sampling of infaunal decapods in Bahía Málaga, on the Pacific coast of Colombia in April 2009 yielded two male and one female specimens of an undescribed species of Axianassa. In addition, a single male specimen of Leptalpheus sp., which at first glance appeared to be identical to the western Atlantic L. axianassae, was collected at the same locality. However, a direct comparison of the Colombian specimen with four Brazilian specimens of L. axianassae revealed some morphological characters separating the eastern Pacific species from its presumed western Atlantic sister species. In the present study, a new species of Axianassa and a new species of Leptalpheus, its burrow associate, are described and illustrated. Material is deposited in the collections of the Museo de Historia Natural Marina de Colombia – MHNMC-INVEMAR, Santa Marta, Colombia (INV CRU), and Museu de Zoologia, Universidade de São Paulo, São Paulo, Brazil (MZUSP). Carapace length (cl, in mm) was measured along the dorsal midline from the tip of the rostrum (or rostral projection) to the posterior margin of the carapace. Comparative material of Axianassa and Leptalpheus examined in this study is as follows: Axianassa australis Rodrigues & Shimizu, 1992: 1 male (cl 8.3 mm), MZUSP 33013, USA, Florida, Fort Pierce Inlet, North Causeway Island, Little Jim Bridge, near Stan Blum Memorial Boat Launch, mudflat, 0.1-0.3 m at low tide, in burrows, leg. A. Anker, 24.vii.2009; 1 male (cl 7.8 mm), MZUSP 33004, Brazil, unknown locality, leg. S.A. Rodrigues, 24.vi.1984; 1 male (cl 10.0 mm), MZUSP 16683, Brazil, Pernambuco, Vila Velha, leg. S.A. Rodrigues & R.M. Shimizu, 13.v.1995; 3 females (cl 12.2, 12.3, 14.5 mm), MZUSP 16317, Brazil, Rio de Janeiro, Ilha da Marambaia, Praia Suja, leg. A.S. Gomes, vii.2004. Leptalpheus axianassae Dworschak & Coelho, 1999: 1 male, paratype (cl 8.6 mm), 1 female, paratype (cl 8.7 mm), MZUSP 13010, Brazil, São Paulo, São Sebastião, Praia do Araçá, tidal flat, in burrow of Axianassa australis, coll. V.R. Coelho & S.A. Rodrigues, 09.viii.1998; 1 female (cl 4.9 mm), MZUSP 24807, Brazil, Alagoas, Barra de Camaragibe, Rio Camaragibe estuary, 09°18’47.7”S, 35°25’17.0”W, leg. M. Tavares & J.B. Mendonça, 23.x.2011; 1 male (cl 5.2 mm, chelipeds missing), MZUSP 28013, Brazil, Bahia, Boipeba, Castelhanos, sta. 3, 13°39.134’S, 38°53.491’W, mangrove on fossil coral platform, mud, leg. M. Tavares et al., 17.ix.2012. Leptalpheus azuero Anker, 2011: 1 male (cl 2.4 mm, carapace damaged), INV CRU8364, Colombia, Bahía Málaga, La Plata, 04°02’N, 77°13’W, mudflat, in burrow of unknown host, leg. A. Anker, 25.iv.2009 [COL-00100].