Ruffosius fluminensis, Souza-Filho, 2011

Souza-Filho, Jesser F., 2011, First record of the family Cheidae (Amphipoda, Gammaridea) from the Brazilian coast, with description of two new genera and new species, Journal of Natural History 45 (5 - 6), pp. 327-346 : 337-344

Ruffosius fluminensis sp. nov.

( Figure 6–9 )

Etymology

From the Latin flumen meaning stream or river; also it is a traditional Latinization used in Brazil for something from Rio de Janeiro State, Brazil.

Material examined

Holotype, female 4.7 mm, Baía de Sepetiba, Praia Escalhau (23 ◦ 00 ′ 10.66 ′′ S, 43 ◦ 56 ′ 13.94 ′′ W), intertidal, December 2007, R. S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T. Cabrini and L. Galhardo col., MNRJ 21823 .

Paratypes: female (dissected and mounted on three slides); Praia Vermelha, Rio de Janeiro, September 2005, E. Omena col., MNRJ 21825 ; 2 females, 2 ovigerous females, Baía de Sepetiba, Praia Escalhau (23 ◦ 00 ′ 10.66 ′′ S, 43 ◦ 56 ′ 13.94 ′′ W), intertidal, December 2007, R . S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T . Cabrini and L. Galhardo col., MNRJ 21822 ; female; Praia Vermelha , Rio de Janeiro, September 2005, E. Omena col., MNRJ 21824 ; 2 females, 2 ovigerous females, Baía de Sepetiba, Praia Escalhau (23 ◦ 00 ′ 10.66 ′′ S, 43 ◦ 56 ′ 13.94 ′′ W), intertidal, December 2007, R . S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T . Cabrini and L. Galhardo col., DOUFPE 14646; 26 females and two ovigerous females, Baía de Sepetiba, Praia da Estopa (22 ◦ 59 ′ 29.10 ′′ S, 43 ◦ 55 ′ 20.90 ′′ W), intertidal, December 2008, R . S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T . Cabrini and L. Galhardo col., DOUFPE 14647; 23 females and 7 ovigerous females, Baía de Sepetiba, Praia Sul (23 ◦ 00 ′ 34.32 ′′ S, 43 ◦ 56 ′ 02.82 ′′ W), intertidal, December 2008, R . S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T . Cabrini and L. Galhardo col., DOUFPE 14648; 20 females and 5 ovigerous females, Baía de Sepetiba, Praia Escalhau (23 ◦ 00 ′ 10.66 ′′ S, 43 ◦ 56 ′ 13.94 ′′ W), intertidal, December 2007, R . S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T . Cabrini and L. Galhardo col., DOUFPE 14649; 21 females and 9 ovigerous females, Baía de Sepetiba, Praia do Boi (22 ◦ 56 ′ 47.82 ′′ S, 43 ◦ 52 ′ 35.78 ′′ W), intertidal, 20 August 2009, R . S. Cardoso, G. Mattos, C. H. Caetano, F. Meireis, T . Cabrini and L. Galhardo col., DOUFPE 14650.

Description

Based on paratype female, 4.8 mm (MNRJ 21825). Head subequal to pereonites 1–4 combined; eyes well-developed; rostrum long, ventral margin sinuous, cheek strongly developed, tip with a sensory organ. Antenna 1 and 2 inserted on ventral margin of head. Antenna 1 shorter than antenna 2; article 1 wider than long (1.3 ×), anterodistal corner with seven robust and long setae and two pappose setae; article 2 longer than article 3 (1.5 ×), distal margin with seven robust setae and two pappose setae, medial margin with a comb of three robust setae; article 3 anterodistal corner with three simple setae and three pappose setae; assessor flagellum 0.6 × primary flagellum length, with five articles; primary flagellum with seven articles, aesthetascs. Antenna 2 non-ensiform, article 3 shorter than article 4 (0.4 ×), with one robust seta on anterodistal corner and three long setae on posterior margin; article 4 with six combs of facial robust setae being two facial (5-6), two subdistal (4-5) and two distal (4-3); article 5 shorter than article 4 (0.8 ×), anterior margin with one comb of four robust setae and one pappose seta, posterior margin with three combs of robust setae (4-5-4), distal margin with four long and robust setae and three pappose setae; flagellum with seven articles.

Mandible with small molar, conical, non-triturative, setulose, with two robust setae apically; palp article 2 moderately inflated, with four marginal setae; article 3 longer than article 2 (1.1 ×), with one long seta on facial margin, distal margin oblique bearing six long setae; left mandible incisor six dentate, lacinia mobilis large, five dentate; setal row with four robust serrate setae and four plumose setae; right mandible incisor seven dentate, lacinia mobilis small, triangular, with a small lateral spine; setal row with four robust serrate setae and five plumose setae. Lower lip mandibular process well developed. Maxilla 1 inner plate both margins setulose and with three long distal setae; outer plate with two rows of serrate robust setae not dissimilar in length, outer line with four setae and inner with three; palp inner margin with three long setae, distal margin with three long setae. Maxilla 2 outer plate slightly longer than inner plate, with marginal and apical plumose setae; inner plate with a row of submarginal setae. Maxilliped inner plate short, not reaching halfway of article 1 of palp, with one distal robust seta and five long setae; outer plate reaching the end of article 1 of palp, with five marginal robust setae; palp long, article 2 inner margin lined with long and short setae, 1.9 × length of article 3, article 3 distal margin setose, dactylus longer than article 3.

Gnathopod 1 subchelate, eusirid form, longer and more slender than gnathopod 2; coxa rectangular, both anteroventral and posteroventral corner with a shallow excavation; basis elongate, slender (4.2 × as long as wide), widened distally, anterior margin with long setae; ischium subequal to merus; propodus 0.8 × length of basis, posterior margin with long setae, subdistal margin with a excavation to fit proximal part of propodus, distal margin truncate; propodus longer than wide (1.2 ×), anterodistal angle with four long setae, posterior margin sinuous, with two tufts of setae; palm obtuse, convex and minutely serrate, palmar corner defined by a subacute process; dactylus long and slender, fitting the palm.

Gnathopod 2 more robust than gnathopod 1; coxa rectangular, both posteroventral corner with a shallow excavation bearing three setae; basis elongate, slender (3.8 × as long as wide), widened distally, anterior margin with four short setae, posterior margin with seven long setae; ischium subequal to merus, with nine long setae; propodus robust, 0.6 × length of basis, posterior margin with 10 long setae, subdistal margin with excavation to fit proximal part of propodus, distal margin truncate; propodus as long as wide, anterodistal angle with four long setae, posterior margin sinuous, with two tufts of setae; palm obtuse, convex and minutely serrate, palmar corner defined by a subacute process; dactylus long and slender, fitting the palm.

Pereopod 3 coxa rectangular, posteroventral corner with five setae; basis rectangular and slender (3.1 × as long as wide), posterior margin with three long setae, posterodistal angle with four long setae; ischium with a tuft of long setae on posterodistal corner; merus with anterodistal corner produced, twice carpus length; carpus robust, posterior margin with long setae, posterodistal corner with one short and robust seta and one long and robust seta; propodus slender (3.2 × as long as wide), posterior margin with 10 robust setae; dactylus robust, 0.6 × propodus length, bearing a subdistal spine.

Pereopod 4 coxa larger than coxae 1–3, widened distally, posterior margin excavated, anteroventral corner rounded, posteroventral corner produced; basis rectangular and slender (3.1 × as long as wide), posterior margin with three long setae, posterodistal angle with six long setae; ischium with a tuft of long setae on posterodistal corner; merus with anterodistal corner produced, 1.9 × carpus length; carpus robust, posterior margin with long setae, posterodistal corner with one long and robust seta; propodus slender (3.2 × as long as wide), posterior margin with six robust setae; dactylus robust, 0.6 × propodus length, bearing a subdistal spine.

Pereopod 5 coxa larger than coxae 6 and 7, wider than long (1.7 ×), bilobate, posterior lobe longer than anterior; basis ovate, anterior margin with five long setae, anteroventral corner with two setae, posterior margin rounded with posteroventral corner rounded and produced; ischium wider than long (1.6 ×); merus anterior margin with two combs of robust setae (3-8), posterior margin expanded with three long setae, posterodistal corner with four robust setae and three long setae; carpus 1.7 × as long as wide, anterior margin with three combs of robust setae (4-6-6), posterior margin slightly expanded, with one robust seta halfway, posterodistal corner with three robust setae and two long setae; propodus subequal to carpus, 2.9 × longer than wide, anterior margin with two combs of robust setae (3-4), anterodistal corner with three robust setae, posterior margin with one robust seta, posterodistal corner with two robust setae and one long seta; dactylus robust 0.4 × propodus length, with a short subdistal spine on anterior margin.

Pereopod 6 coxa wider than long (1.5 ×), bilobate, posterior lobe longer than anterior, crenulate; basis ovate, anterior margin with 14 long setae, anteroventral corner with four setae, posterior margin rounded with posteroventral corner rounded and produced; ischium wider than long (2.1 ×); merus anterior margin with three combs of robust setae (3-3-4), posterior margin expanded with four long setae and one robust seta, posterodistal corner with five robust setae and one long seta; carpus 1.3 × as long as wide, anterior margin with three combs of robust setae (4-4-6), posterior margin slightly expanded, with two robust setae, posterodistal corner with three robust setae; propodus subequal to carpus, 3.2 × longer than wide, anterior margin with two combs of robust setae (2-5), anterodistal corner with four robust setae, posterior margin with one robust seta, posterodistal corner with two robust setae; dactylus robust 0.3 × propodus length, with a short subdistal spine on anterior margin.

Pereopod 7 coxa longer than wide (1.4 ×), posterior margin crenulate with five setae; basis ovate, anterior margin without setae, anteroventral corner with a single short seta, posterior margin rounded with posteroventral corner rounded produced; ischium wider than long (1.4 ×); merus anterior margin with three combs of robust setae (2-3-5), posterior margin moderately expanded with two long setae, posterodistal corner with three robust setae; carpus 1.2 × as long as wide, anterior margin with three combs of robust setae (3-4-6), posterior margin slightly expanded, with two robust setae, posterodistal corner with two robust setae; propodus slightly longer than carpus, 4 × longer than wide, anterior margin with two combs of robust setae (3-5), anterodistal corner with three robust setae, posterior margin with one robust seta, posterodistal corner with two robust setae; dactylus robust 0.4 × propodus length, with a short subdistal spine on anterior margin.

Epimera 1 posterior margin convex, with seven slender setae. Epimera 2 posterior margin straight, with six slender setae, facial margin with nine long and plumose setae, ventrofacial margin with six long and plumose setae. Epimera 3 posterior margin convex with six slender setae.

Uropod 1 biramous, peduncle longer than outer ramus (1.75 ×), outer margin with six robust setae, inner margin with three robust setae, basofacial margin with one robust seta; outer ramus shorter than inner ramus, with three apical robust setae; inner ramus with two marginal robust setae and three apical robust setae.

Uropod 2 uniramous, peduncle 1.2 × ramus length, outer margin with three robust setae, outer distal corner with one long robust seta (0.8 × ramus length); ramus with three apical robust setae.

Telson wider than long (1.7 ×), deeply cleft, each lobes laterodistally pointed, bearing one subdistal robust seta, one slender seta and one pappose seta, lateral margins with two pappose setae.

Complementary description

Female paratype 4 mm (MNRJ 21822). Uropod 3 peduncle shorter than inner ramus, inner margin with two plumose setae and one distal robust seta, outer distal margin with six robust setae; outer ramus 2-articulate, article 1 3.1 × article 2 length, outer margin with four combs of robust setae (1-3-2-2), inner margin with six plumose setae, article 2 truncate distally, with six distal setae; inner ramus lanceolate, shorter than article 1 of outer ramus (0.94 ×), outer margin with three setae, inner margin with six plumose setae and two robust setae, distal margin with three plumose setae.

Male

Unknown.

Geographic distribution

Praia Vermelha and Baía de Sepetiba, Rio de Janeiro, Brazil .

Key to species of Cheidae

1. Gnathopod 1 and 2 very robust; coxae 1–4 relatively short ( Figure 5 ); uropod 2 uniramous........................... Ruffosius fluminensis gen. et sp. nov.

Gnathopod 1 and 2 feeble; coxae 1–4 long ( Figure1 ); uropod 2 biramous............................................................................ 2

2. Poorly developed eyes; antenna 2 article 1 with posterodistal corner rounded and produced, maxilla 1 with palp 2-articulate; right mandible with lacinia mobilis................................. Microcheus nortoni gen. et sp. nov.

Well-developed eyes; antenna 2 article 1 with posterodistal corner not produced, maxilla 1 with palp 1-articulate; right mandible lacking lacinia mobilis...................................... Cheus annae Thurston, 1982

Figures

Figure 1. Microcheus nortoni gen. et sp. nov., holotype, female 2.1 mm, Praia Jardim do Éden, Tramandaí, Rio Grande do Sul, MNRJ 21821. Scale bars 0.1 mm.

Figure 5. Microcheus nortoni gen. et sp. nov., paratype, female 2.2 mm, Praia Jardim do Éden, Tramandaí, Rio Grande do Sul, MNRJ 21826. Scale bars: Hb, Hd = 0.5 mm; M = 2 µm.

Figure 6. Ruffosius fluminensis gen. et sp. nov., paratype female, 4.8 mm, Praia Vermelha, Rio de Janeiro, MNRJ 21825. Scale bar 0.1 mm.

Figure 7. Ruffosius fluminensis gen. et sp. nov., paratype female, 4.8 mm, Praia Vermelha, Rio de Janeiro, MNRJ 21825. Scale bar 0.1 mm.

Figure 8. Ruffosius fluminensis gen. et sp. nov., paratype female, 4.8 mm, Praia Vermelha, Rio de Janeiro, MNRJ 21825. Scale bar 0.1 mm.

Figure 9. Ruffosius fluminensis gen. et sp. nov., paratype female, 4.8 mm, Praia Vermelha, Rio de Janeiro, MNRJ 21825. Ur3 from paratype female, 4 mm, Baía de Sepetiba, Praia Escalhão, MNRJ 21822. Scale bar 0.1 mm.