A new species and record of Biancolina Della Valle, 1893 (Amphipoda, Senticaudata, Ampithoidae) from the Southwestern Atlantic

. Here we describe a new species of Biancolina from Pernambuco, Brazil, found in association with the brown algae Sargassum spp., between 0.5 and 1.0 m depth. The new species differs from its congeners mainly by the following combination of characters: antenna 1 twice the length of antenna 2, lacinia mobilis present in both mandibles, article 4 of the maxilliped bulbose; coxa 6 with anteroventral lobe well developed as in posteroventral lobe, peduncle of uropod 1 weakly setose, palm of pereopods 5-7 lacking robust seta. This is the first record of Biancolina from the southwestern Atlantic.


INTRODUCTION
The species of Biancolina Della Valle, 1893 are minute amphipods (> 2 mm in adults) (Hughes & Poore, 2016).They live in association with macroalgae, boring tunnels into the algal tissue using its modified conical-shape mouthparts.Moreover, they have subglobular head, semicylindrical body, prehensile pereopods, and reduced urosomites (with modified uropods and telson).Such body modifications are considered convergent morphologies also observed in other boring amphipods (Mejaes et al., 2015).Some species are host-specific, living in one or two species of brown algae, such as B. japonica Ishimaru, 1996 which is found exclusively in Sargassum linearifolium and S. vestitum, whereas S. brassicacephala lives in the floating Sargassum natans and S. fluitans.
Biancolina was first described as part of the family Dexaminidae by Della Valle (1893) and transferred to Ampithoidae by Stebbing (1899).Stebbing (1906) synonymized B. algicola Della Valle, 1893 with Amphithoe cuniculus Stebbing, 1874 (= Ampitholina cuniculus).Years later, Ruffo (1953) revalidated B. algicola, erected the genus Ampitholina within Ampithoidae, and transferred Biancolina to the family Prophliantidae Nicholls, 1939. Then, Gurjanova (1958) transferred Biancolina to the newly described fam-ily Eophliantidae.Barnard (1972), erected a monotypic family Biancolinidae, highlighting the differences between two closely related genera: Biaconlina and Amphitolina Ruffo, 1953. Bousfield (1978) transferred Biancolinidae to the Corophioidea Leach, 1814, but did not discuss it.Ishimaru (1996) reviewed the family and followed Bousfield classification.Myers & Lowry (2003) excluded Biancolinidae from their phylogenetic analysis of the Corophiidea Myers & Lowry, 2003, due to the absence of some of the most important synapomorphies of the group, such as silk glands on the basis of pereopods 3 and 4; slender and robust setae on the rami of uropod 3; and a dorsoventrally thickened telson, characters observed by Barnard (1972) and Bousfield (1978).However, Serejo (2004) and Lowry & Myers (2013) show that the Biancolinidae was related to Talitrida Rafinesque, 1815, the later authors recognized it as a monotypic superfamily, 'based on the loss of palps of mandible and maxilla 1 and the presence of curl-tipped setae on the oostegites' , but with uropod 3 biramous (Myers & Lowry, 2003).Recently, Sotka et al. (2017) performed molecular analysis and based on that transferred the genus Biancolina back to Amphithoidae.
Up to date, there are seven described species in the genus.A wide geographical distribution, such as North Atlantic (USA and Cuba); Mediterranean Sea, Black Sea; Pacific Ocean, Japan, Australian, Hawaii, Fiji, (Hughes & Poore, 2016), however, none of them known from South Atlantic Ocean.In this paper, we describe a new species of the genus Biancolina from Northeast Brazil, Pernambuco state, comprising the first record of the genus from the Southwestern Atlantic.Also, this record increases to four the number of genera of the family Ampithoidae known from Brazilian waters.

MATERIAL AND METHODS
The studied specimens were found in association with brown algae of the genus Sargassum collected between 2018 and 2020 at the Praia do Paraíso, Suape Bay, Pernambuco (08°21′23.178″S,34°57′06.386″W),at depths ranging from 0.5 to 1.0 meters.In order to better separe amphipods from the macroalgae, the algal frond was placed in water with a few drops of formalin for 10 minuntes and after washed with seawater and fixed with buffered 4% formalin.At the laboratory, the specimens were transferred 75% alcohol.The type material is deposited in Crustacea Collection of Museu de Oceanografia Prof. Petrônio Alves Coelho (MOUFPE).Appendages and mouthparts of dissected specimens were mounted on glass slides and sealed with glycerol gelatin, after stained with Chlorazol Black.The crustacean setae classification proposed by Watling (1989) is here adopted.Digital illustrations were made up using CorelDRAW X7 following Coleman (2003) modified method.

Taxonomy
Head: Head longer than deep; inferior margin produced.Antenna 1 longer than antenna 2 (more than 2 ×); peduncular article 1 shorter than article 2; article 2 longer than article 3; article 3 subequal to article 1; primary flagellum with 10 articles; accessory flagellum absent.Antenna 2 slender, similar to antenna 1; peduncle articles 3 to 5 not densely setose on ventral margin; peduncle article 4 subequal in length to article 5; flagellum subequal to peduncular article 5, flagellum 3 articles.Upper lip directed forwards, at around 45 degrees, lateral margins without midlateral notches.Mandible molar absent, accessory setal row with 3 robust setae; palp absent.Lower lip outer plates entire, lateral lobe distinctly longer than medial lobe, without an apical nipple; mandibular lobe with straight margins, rounded apically.Maxilla 1 inner plate with 1 slender setae; palp absent.Maxilla 2 inner plate narrower than outer plate; inner plate without oblique setal row.Maxilliped outer plate without a row of robust setae along medial margin.
Habitat: Living in association with Sargassum spp. between 0.5 and 1.0 m depth.
Distribution: Known only from type locality.

Figure 5 .
Figure 5. Geographical distribution of all known species of the genus Biancolina.
Andrade, R.M. & Souza-Filho, J.F.: A new species and record of Biancolina from the Southwestern Atlantic Uropod 1 sexually dimorphic; short, reaching end of uropod 2 peduncle; peduncle 0.7 × longer than wide; peduncle without robust setae, peduncle without slender setal fringe; peduncle outer margin with 3 very long simple setae; peduncle distal margin with 4 slender setae; distoventral spur vestigial or absent; inner ramus shorter than outer ramus, robust setae absent, slender setae present; outer ramus broad with fluted like water spout, connected with ductular structure originated from inside of ⅓ of the distal part; outer ramus broad, length about 2-4 × as long as broad, marginal without robust setae, slender setae present.