Liropus guerragarciai, Mauro, Fábio Da Motta & Serejo, Cristiana Silveira, 2015

Liropus guerragarciai View in CoL sp. nov.

( Figs. 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Material examined: 1 male holotype, 4.29mm, 22º 40' 58,651" S 40º 17' 38,462" W, 988m, MNRJ 24705; 1 allotype female, 22º 40' 58,651" S 40º 17' 38,462" W, 988m, MNRJ 24706; 1 male, 23º10´22,254"S 40º 56´46,365", 1335m; MNRJ 24707; 1 juvenile, 23º45´18,413"S, 2423m, MNRJ 24778; 2 females, 39º 44' 21,079" W, 1932m, MNRJ 24775; 1 female, 1 juvenile, 21º41´12, 557"S 40º1´56,073”W, 702m, MNRJ 24777; 1 male, 1 female, 1 juvenile, 23º 1´30, 862"S 40º45´22, 948"W, 964m, MNRJ 24776; 1 male 23º 13' 46,474" S 40º 55' 56,178" W, 986m, MNRJ 24707; 1 male, 21º 41' 12,557" S 40º 1' 56,073" W, 702m, MNRJ 24708.

Diagnosis. Antenna 2 flagellum 2-articulate with triangular process at distal part of article; head and pereonites projections absent; gnathopod 2 basis with proximal constriction; male with 1 pair of lobes and 1 pair of 2– articulate well developed appendages, pereopod 5 3-articulate. Pereonite 2 1.5x basis of gnathopod 2; pereonites 2– 7 up to five times longer than wide; body slender; pereopods 3–4 subequal in length and width; gills elliptical and reduced; abdomen with 1 pair of 2-articulate well developed appendages.

Description. Male, holotype, 4.29mm. Head: Antennae: Antenna 1 flagellum 4-articulate, 1.25 times longer than antenna 2; Antenna 1 and Antenna 2 first articles peduncle with distal acute projection; flagellum 4-articulate; Antenna 2 first article with distal-lateral triangular projection; flagellum 2-articulate. Left mandible incisor 5- toothed; lacinia mobilis 5-toothed; row of three pectinate setae laterally; molar conspicuous with five small teeth, little differentiated; palp second article with 1 distal-lateral setae; last article with formula 1-5-7-1. Right mandible with 5 acute tooth; lacinia mobilis strongly serrate; palp distal part with row of 5 stocky projections and row of 10 setae; molar strong. Lower lip with inner and outer lobes well marked, inner lobes strongly round and outer lobes stronger and somewhat elliptical. Maxilliped inner lobe smaller than outer lobe; outer lobe with row of six setae; palp second article with one distal setae, second article with four distal setae, last article inner margin with several small serrate setae and one distal setae. Maxilla 1 outer lobe with five denticulate setae, palp with five setae.

Thorax: Gnathopod 1 ischium and merus subequal in length; carpus about 1.5 times longer than merus with row of six setae distally; propodus with sub-ventral row of five small setae, and a row of five large setae at medialdistal part; palm serrate; dactylus reaching end of propodus, smooth. Gnathopod 2 basis with proximal constriction, ischium 0.6 times size of merus, carpus smaller; palm with several micro-setae ventrally, with proximal robust seta, a small concavity followed by an acute teeth and an acute concavity. Pereopods 3 and 4 1-articulate with pair of apical setae. Pereopod 5 article 2 the largest, article 3 minute, bearing two small setae. Pereopods 6 and 7 missing.

Abdomen: Male with 1 pair of lobes and 1 pair of 2-articulate well developed appendages.

Female, allotype, 4.12mm. Body smooth; antenna 2 peduncle surpassing antenna 1 peduncle; oostegites strongly setose; oval projection at mid-length of pereonite 5. Gnathopod 2: ischium with 3 mid-lateral setae; twice as long as merus; merus rounded ventrally; propodus with small cavity; palm weakly serrate; dactylus smooth.

Distribution. Campos Basin, Brazil, 702–2423m.

Etymology. Species is named in honor to Dr. José Manuel Guerra-García, after his vast contribution to the knowledge of caprellid amphipods.

Remarks. Liropus is composed by ten species (including the present material), with a single previous record for Brazil, L. nelsonae ( Guerra-García, 2003a). Liropus guerragarciai sp. nov can be assigned to Liropus for the following characters: body elongate; head and pereonites lacking spines or projections; pereopods 3–4 1-articulate; pereopod 5 reduced (and less than 5-articulate) and medially inserted; male abdomen appendages present and strongly reduced, female with a pair of lobes and no appendages. Guerra-García & Hendrycks (2013) described L. minusculus for the Eastern Pacific and comment on the distribution of the genus Liropus . Five species occur in the Altantic Ocean, two in the Mediterranean Sea and two in the Pacific Ocean. From the ten species known, eight have ommatidia ( Table 3 View TABLE 3 ). Liropus guerragarciai sp. nov. is close related to L. nelsonae Guerra-García, 2003 in a 3-articulate pereopod 5, but differs as abdomen lobes and appendages are well developed and fully 2-articulate (versus vestigial, rudimentary). It also resembles L. elongatus Mayer, 1890 , L. gracilis Chevreaux, 1927 and L. minimus Mayer, 1890 in a smooth and strongly elongate body and the presence of a sharp constriction on basis of gnathopod 2 that bends the appendage forward or backwards. Liropus guerragarciai sp. nov. can be distinguished from L. minimus and L. elongatus in pereopod 5 3-articulate (versus 2-articulate) ( Table 3 View TABLE 3 ). Liropus nelsonae was recorded at depths from 900 to 1000m from off Pernambuco state ( Guerra-García, 2003a). Liropus guerragarciai sp. nov. has been recorded at similar depths ( 700–1900m) and was the only caprellid species to be found at this bathyal range in the HABITATs Project at the Campos Basin, Rio de Janeiro.