Transisthmian differentiation in the tree-climbing mangrove crab Aratus H. Milne Edwards, 1853 (Crustacea, Brachyura, Sesarmidae), with description of a new species from the tropical eastern Pacific Author Thiercelin, N. Author Schubart, C. D. text Zootaxa 2014 3793 5 545 560 journal article 45886 10.11646/zootaxa.3793.5.3 c6cef31e-25a7-4d04-ae88-ddaa81ed3e86 1175-5326 229915 461B59C7-AC41-4B57-9454-81B35432699E Aratus pisonii (H. Milne Edwards, 1837 ) ( Figs. 3 A, B, E, F, I, J, M, N; 4A, B, E, F, I, J; 6A, B, C, D, E, F, G, H, I, J, K, L, M, N, O , P, Q, R, S, T, U, V, W, X; 7A, B, C, D, E, F, G, H, I, J, K, L, M, N, O , P, Q, R; 8A, B, G, H, M, N, S, T; 9A, B, G, H, M, N) Aratu pinima Piso & Marcgrave 1648 : 185 Sesarma pisonii H. Milne Edwards, 1837 : 76 , pl. 19, figs. 4, 5 Aratus pisoni H. Milne Edwards 1853 : 187 Aratus pisonii Rathbun 1918 : 322 , pl. 96, figs. 1, 2.— Boone 1930 : 207 , pl. 70.— Warner 1967 : 321 .; 1968: 249, figs. 1–6.— Beever et al . 1979 : 317 .— Díaz & Conde 1989 : 148 .— Schubart et al . 2000 : 179 .— Leme 2002 : 553 .— Fratini et al . 2005 : 219 .—Schubart et al . 2006: 193. Type material. Two dry specimens (male, 19.6 × 20.6mm , female, 19.9 × 20.6mm ) from the type series in the Muséum National d'Histoire Naturelle, Paris ( MNHN B3341, photographs) were recognised as syntypes by N.K. Ng, T. Naruse, P.A. Rodriguez Moreno and D. Guinot (pers. comm., work in progress), of which one will be designated as the lectotype . Type locality: Martinique . Material examined. Jamaica . St. Ann Parish, Priory, 18°27.1'N- 77°13.5'W , 1 ♂ (22.46 × 22.61mm ) ( RMNH . CRUS .D.55078), coll. C.D. Schubart et al. , 8 Mar.2011 ; St. Ann Parish, Priory, New Seville, 18°26.756'N- 77°12.644'W , 1 ♂ (26.5 × 24.8mm ) ( NHMW 25475), coll. C.D. Schubart & P. Koller, 1 Mar.2011 . Dominican Republic . Bahía de Las Calderas, Las Salinas, 18°12.75'N- 70°32.46'W , 1 ♂ (18.45 × 17.65mm ) (MNHN-IU-2009-3094), coll. C.D. Schubart, R. Landstorfer, N. Rivera, 1 Nov.2006 ; Bahía de Luperón, 19°53.76'N- 70°57.56'W , 2 ♂ (18.65 × 17.3, 20.2 × 19.35mm ) ( SMF 43534), coll. C.D. Schubart, R. Landstorfer, N. Rivera, 25 Oct.2006 . Costa Rica . Limón, Puerto Viejo de Talamanca, Punta Uva, 9°37.930'N- 82°40.200'W , 1 ♂ (20.35 × 20.10mm ) (MNHN-IU-2009-5103), Coll. C.D. Schubart & I. Wehrtmann, 28 Jan.2006 . Brazil . Pará, Marapanim, Marudá, FIGURE 3. First male left gonopods of Aratus pisonii and Aratus pacificus n. sp. observed in scanning electron microscopy (SEM) in longitudinal mesial (A–D), dorsal (E–H), lateral (I–L) and ventral (M–P) views. CW × CL in mm. Abbreviations: s, suture; t, chitinous tip. FIGURE 4. First male left gonopods of Aratus pisonii and Aratus pacificus n. sp. observed in scanning electron microscopy (SEM) in apical view (A–D), detail of the endpiece in lateral view (E–H) and total view (I–L). Abbreviation: d, depression. 0°37.023'S- 47°37.946'W , 1 ♂ (16.65 × 16.25mm ) ( SMF 43533), coll. C.D. Schubart & N. Thiercelin, 15 Nov. 2010 ; Bahia, Itacaré, Rio de Contas, 14°16.494'S- 38°59.869'W , 2 ♂ (17.85 × 17.8, 17.05 × 16.55 mm ) ( MZUSP 28251 & MZUSP 28255), coll. C.D. Schubart & N. Thiercelin, 11 Nov.2010 . Description. First male gonopod ( Figs. 3 A, B, E, F, I, J, M, N; 4A, B, E, F, I, J; 6A, B, C, D, E, F, G, H, I, J, K, L, M, N, O , P, Q, R, S, T, U, V, W, X; 7A, B, C, D, E, F, G, H, I, J, K, L, M, N, O , P, Q, R; 8A, B, G, H, M, N, S, T; 9A, B, G, H, M, N) elongated. Stem triangular in cross section; basal diameter wider than medial diameter. Mesial, ventral faces flat; slanted suture (sperm channel) clearly marked on dorsal face with terminal section in strongly marked depression; endpiece larger than medial part, easily noticeable in mesial, lateral views, endpiece bulging in lateral view; dorsal part almost spoon-shaped in mesial view. Mesial endpiece of ventral part slightly higher than dorsal part (angle approx. 25° in mesial view); short, chitinous, tip strongly curved (U-shaped) in ventral position, with pore on dorsal margin; suture aligned with chitinous edge of tip on apex of gonopod, with mesial face of chitinous tip/dorsal suture angle of approx. 115°; mesial face of chitinous tip/mesial face of approx. 110°; small denticles on lateral face of chitinous process. Small depression in medial position near tip. Large number of long setae on apex around chitinous tip, as well as on lateral, dorsal sides of endpiece lateral bulge. One line of setae on endpiece at edge between mesial, dorsal faces. Few single short setae on gonopod. Presence of few plumodenticulate setae on dorsal part of endpiece bulge. Biology. There is an extensive body of scientific literature on Aratus pisonii sensu stricto , as almost all the studies concerning this genus were conducted in the Atlantic Ocean. A detailed summary of this literature was given by Cuesta et al. (2006), including life history aspects ( Warner 1967 , Díaz & Conde 1989 , Leme 2002 ) and larval description ( Warner 1968 ). Geographical distribution. Aratus pisonii sensu stricto is now restricted to the Atlantic Ocean, from Florida to south Brazil (Santa Catarina) including the Caribbean Sea and the Gulf of Mexico ( Beever et al. 1979 , Melo 1996 ). Remarks. The species was named in honour of Willem Piso, who made the first description and drawing of this species in 1648 ( Piso & Marcgrave 1648 ). Piso, however, seems to have confused A. pisonii with Goniopsis cruentata (Latreille, 1803) , a grapsid crab living in the same habitat and also able to climb on mangrove roots and stems, as the colour pattern described in the text does not correspond to the one observed in Aratus .