New and additional records of Metharpinia Schellenberg, 1931 and Microphoxus Barnard, 1960 (Crustacea: Amphipoda: Phoxocephalidae) from Brazilian waters

New records of the species Metharpinia dentiurosoma Alonso de Pina, 2003, M. grandirama Alonso de Pina, 2003, M. iado Alonso de Pina, 2003, Microphoxus cornutus (Schellenberg, 1931) and Mi. uroserratus Bustamante, 2002 are reported for Brazilian waters. A discussion about the Metharpinia-Microphoxus complex is presented based on literature review and new observations of sampled species. Emended diagnoses are presented for the recorded species of Metharpinia and identification keys to world species of Metharpinia and Microphoxus are provided.


INTRODUCTION
Among the collections of phoxocephalids amassed during the cruises of the R/V Prof. Wladimir Besnard conducted along the southeastern Brazilian coast (São Paulo, Rio de Janeiro andSanta Catarina) in 1970 and1971, between 15 and 98 m, were three species of Metharpinia Schellenberg, 1931, and two of Microphoxus Barnard, 1960 representing new and additional records to the Brazilian coast.
These records are discussed herein. Opportunity was taken to redescribe and illustrate Metharpinia dentiurosoma, M. grandirama, M. iado Alonso de Pina, 2003, all previously known only from farther south (Argentina) and now recorded for the first time from Brazilian waters. Microphoxus cornutus (Schellenberg, 1931), originally described from Punta Arenas (Chile) and subsequently recorded from southeastern Brazil, and Mi. uroserratus Bustamante, 2002, originally described from southeastern Brazil, are recorded from additional Brazilian localities. Both species are redescribed and illustrated.
Identification keys to the world species of Metharpinia and Microphoxus are provided.

MATERIAL AND METHODS
The material studied herein was collected during the MBT (Mini Biological Trawl) Project from Instituto Oceanográfico, Universidade de São Paulo. All specimens were preserved in 70% ethanol and deposited at the Crustacea Collections of the Universidade do Estado do Rio de Janeiro (UERJ) and Museu de Zoologia da Universidade de São Paulo (MZUSP).
For the taxonomic study, the mouthparts and appendages were dissected and mounted in glycerin gel slides. The drawings were made under an optical microscope with camera lucida, Motic BA-310, and digitized with CorelDRAW 2018. The setal/spine classification adopted in this paper follows Garm & Watling (2013) and the nomenclature of gnathopod palms is based on Poore & Lowry (1997).
The identification key for the species of Microphoxus was in part updated from Bustamante (2002). As we have not had access to the types of the species currently included in Microphoxus, the key is based on personal observations and information from the literature.
Sexual dimorphism: Based on male (UERJ 411). Body, smaller in size. Eyes, larger and more pigmented.
Remarks: Metharpinia dentiurosoma was described with material from Buenos Aires (Argentina) and this is the first record of the species for Brazilian waters. Due to characteristics of antennae, mandibles, gnathopods and uropods, this species seems to be morphologically close to Mi. uroserratus described for Sepetiba Bay, Rio de Janeiro state, Brazil (22°58′S, 44°02′W). However, it can be distinguished by the latter by presenting: head with a visible acute dorsolateral projection, rostrum slightly exceeding apex of first article of antenna 1; epimeral plate 3 posteroventral corner strongly produced into a large tooth and facial margin with an oblique row of stout setae.
Geographic distribution: Argentina: Argentine Sea; Brazil (this report): coast of the states of Rio de Janeiro, São Paulo and Santa Catarina.
Geographic distribution: Argentina: Argentine Sea; Brazil: coast of the Santa Catarina state.