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| Alpheus margaritae |
Abstract
Two new species of the family Alpheidae: Alpheus margaritae sp. n. and Leptalpheus melendezensis sp. n. are described from Santa María-La Reforma, coastal lagoon, SE Gulf of California. Alpheus margaritae sp. n. is closely related to A. antepaenultimus and A. mazatlanicus from the Eastern Pacific and to A. chacei from the Western Atlantic, but can be differentiated from these by a combination of characters, especially the morphology of the scaphocerite and the first pereopods. Leptalpheus melendezensis sp. n. resembles L. mexicanus but can be easily differentiated because L. melendezensis sp. n. has the anterior margin of the carapace broadly rounded and has only one spine on the mesial margin of ischium in the major cheliped, versus an acute rostrum and an unarmed major cheliped. Additionally, a phylogenetic analysis was used to explore the relationships of these two new taxa. These results show that Alpheus margaritae sp. n. and Leptalpheus melendezensis sp. n. are indeed related to the species against which we are comparing them, and demonstrate that they can be considered as different species. Additional specimens of Leptalpheus cf. mexicanus, Ambidexter panamensis and A. swifti are recorded for the first time in the Santa María-La Reforma coastal lagoon.
Keywords: Caridea, Crustacea, genetic analysis, Mexican Pacific, new species
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| Figure 1. Alpheus margaritae sp. n. Female paratype from Isla Costa Azul, Santa María-La Reforma costal lagoon, Sinaloa, Mexico (EMU-10581), lateral view, color in life. |
Systematic account
Family Alpheidae Rafinesque, 1815
Genus Alpheus Fabricius, 1798
Alpheus margaritae sp. n.
Diagnosis: Ocular hoods unarmed. Antepenultimate segment of third maxilliped broad. Scaphocerite with concave lateral margins, distolateral tooth overreaching the distal margin of the inner blade, inner blade almost reaching the distal end of antennular peduncle. Major cheliped markedly compressed, with grooves on both dorsal and ventral margins. Pereopods 3–5 with dactylus subspatulate; ischium of third and fourth pereopods with ventral spine.
Habitat: Soft mud with gravel composed of shells and rocks, in intertidal.
Distribution: Only known from Bahía Santa María-La Reforma coastal lagoon, Sinaloa, Mexico.
Etymology: The species is named after Dr. Margarita Hermoso Salazar in recognition of her contributions to the knowledge of Mexican carideans.
Genus Leptalpheus Williams, 1965
Leptalpheus melendezensis sp. n.
Diagnosis: Frontal margin of carapace broadly rounded, weakly produced, without dorsal crests. Antenna with carpocerite longer than scaphocerite, slightly shorter than antennular peduncle. Major cheliped slender; ischium armed with strong ventromesial spine directed upward; fingers slightly twisted laterally, not gaping when closed; without adhesive discs; dactylus with strong proximal tooth on cutting edge, tip acute, crossing distally with tip of pollex; propodus of pereopods 3 and 4 with two ventral spines; propodus of fifth pereopod with two distal rows of setae on ventral margin.
Habitat: Sandy beach, associated with burrows of N. tabogensis.
Distribution: Known only from Meléndez Island, Bahía Santa María-La Reforma, Sinaloa, Mexico.
Etymology: The name of the species is derived from Meléndez Island, the type locality.
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José Salgado-Barragán, Manuel Ayón-Parente and Pilar Zamora-Tavares. 2017. New Records and Description of Two New Species of Carideans Shrimps from Bahía Santa María-La Reforma Lagoon, Gulf of California, Mexico (Crustacea, Caridea, Alpheidae and Processidae). ZooKeys. 671; 131-153. DOI: 10.3897/zookeys.671.9081
