Paracaprella pusilla Mayer, 1890

Mauro, Fábio Da Motta & Serejo, Cristiana Silveira, 2015, The family Caprellidae (Amphipoda: Caprelloidea: Caprellidae) from Campos Basin, Southwestern Atlantic, with a key of species occurring in Brazil, Zootaxa 4006 (1), pp. 103-127 : 120-123

Paracaprella pusilla Mayer, 1890

Paracaprella pusilla Mayer, 1890 , p.41, pl.1 figs. 28–30.— Schellenberg, 1928, p. 677–678.—Edmondson & Mansfield, 1948, p.208–209, fig.4.— Barnard, 1955, p. 99.— Day & Morgan, 1956, p. 303.— Steinberg & Dougherty, 1957, p. 283–284, figs. 16, 19, 24, 30.— McCain, 1968: 83, figs. 32a–b; 41, 42, 53.— Wakabara et al., 1991: 73.— Serejo, 1998a: 381, fig. 7.— Wakabara & Serejo, 1998: 585.—Guerra-García et al. 2006: 175, figs. 17–19.—Lacerda & Masunari, 2011: 372, fig. 3a. — Ros et al. 2013: 679, fig. 2.

Caprella nigra Reid, 1951 , p.283–284, 289,fig. 58.

Material examined: 1 female 4.2mm, 21º 39' 6,702" S 40º 48' 55,800" W, 22m, MNRJ 24834; 1 male, 4.9mm, 1 female, 2 juveniles, 3.4mm, 22º 6' 16,830" S 40º 43' 45,468", 47m, MNRJ 24835; 1 female, 22º 6' 6,141" S 40º 3' 12,849" W, 153m, MNRJ 24836; 1 female, 22º 6' 22,014" S 40º 43' 42,326" W, 47m, MNRJ 24837; 2 males, 21º 55' 18,212" S 40º 55' 0,708" W, 16m, MNRJ 24838.

Diagnosis. Antenna 1 flagellum 8-articulate; antenna 2 2-articulate; mandibular palp represented by 1–2 setae; male anteroventral projection on pereonite 2 acute; gnathopod 2, basis subequal to pereonite 2, 2x longer than wide, expanded and with proximal knob; merus rounded ventrally.

Description. Male, 4.9mm. Head: head suture present. Left mandible incisor 5-toothed; lacinia mobilis 5- toothed; row with three setae laterally; mandibular palp probably represented by a single setae. Right mandible lacinia mobilis serrate. Molar well developed. Maxilla 1 inner lobe with four spiny setae; palp with 5 setae. Maxilla 2, inner lobe and outer lobe with four setae. Maxilliped inner lobe with two apical setae, outer lobe with three setae laterally; palp article 2 with three setae laterally, article 3 with row of six distal setae and last article with five apical setae.

Thorax: Gnathopod 1 propodus with proximal stout spine; propodus palm serrate; dactylus serrate. Gnathopod 2 with two concavities, the distal one larger and strongly arc-shaped, increasing its size according to male adult development. Pereopod 3: Article 1with 1 setae; article 2 with apical setae. Pereopod 5, 6 and 7 not available. Abdomen: Appendages with three lateral setae, about 0.25 times longer than penes papillae; lobes and apex smooth.

Female, 4.2mm. Notch between head and pereonite 1 present; anterolateral projection on pereonite 2 not so conspicuous. Oostegites on pereonites 3–4 large. Abdomen lobes and apex smooth.

Distribution. Type locality: Rio de Janeiro, Brazil ( Mayer, 1890). Other localities: Atlantic and Pacific Oceans ( McCain, 1968). Mediterranean Sea ( Ros et al. 2013). Brazil: Campos Basin, 16–153m (present sudy), RJ, SP, PR, SC, RJ ( Wakabara & Serejo, 1998; Lacerda & Masunari, 2011).

Ecology. The present species is usually found in shallow waters attached to mangrove roots, seagrasses, hydroids, ascidians, gravel bottoms, ropes, mussels and oysters banks (Guerra-García et al., 2006).

Remarks. At the present time, 10 species of Paracaprella have been described with 4 of them being found in Brazil: P. dubiaski Lacerda & Masunari, 2014 ; P. digitimanus Quitete, 1971 ; P. pusilla and P. t e n ui s Mayer, 1903. Paracaprella pusilla and P. t e nu i s are most commonly found and generally mistaken because of morphological resemblance and similar tropical and subtropical distribution. The main difference between both species relies on mandibular palp, which is represented by 1–2 setae P. pusilla (versus 3-articulate in P. tenuis ). It differs also from P. dubiaski as the mandibular palp is represented by 1–2 setae (versus absent) and from P. digitimanus by the presence of a male proximal gnathopod 2 knob and propodus concavity rounded (versus concavity with indentation forming a strong and dissimilar acute projection). Main morphological differences between species found in Brazil can be found on Table 5 .