Panopeus americanus Saussure, 1857

Oliveira-Rogeri, Lucas, França, Nielson Felix Caetano, Peres, Pedro Augusto & Mantelatto, Fernando L., 2023, Cleaning the mud: Integrative approach clarifies the taxonomy of mud crabs of the genus Panopeus H. Milne Edwards, 1834 (Decapoda: Brachyura: Panopeidae) along the Southwestern Atlantic, Zoologischer Anzeiger 307, pp. 96-124 : 102

3.1. Panopeus americanus Saussure, 1857

( Fig. 1A , 4 A-N)

Panopeus americanus Saussure, 1857: 502 ; Saussure, 1858: 432, pl. 1,

Fig. 8 ; Desbonne and Schramm, 1867: 30; A. Milne-Edwards, 1881: 311; Benedict and Rathbun, 1891: 380; Verrill, 1908: 353, Fig. 16; Rathbun, 1930: 357, pl. 164, Figs. 3 , 4 and 6 ; Rathbun, 1933: 61; Coelho and Ramos, 1972: 190; Abele and Kim, 1986: 50; Melo, 1996: 369; Schubart et al., 2000: 13; Barros and Pimentel, 2001: 30; Bertini et al., 2004: 2201; Braga et al., 2005: 31, Fig. 38; Coelho et al., 2008: 33; Melo, 2008: 11; Ng et al., 2008: 190; Felder et al., 2009: 1082; Vieira and Calazans, 2010: 433; Marochi and Masunari, 2011: 25; Thoma et al., 2014: 96; Hollier, 2018: 292; Mantelatto et al., 2020: 74, Fig. 20E.

Panopeus areolatus Benedict and Rathbun, 1891: 361 , pl. 21, Fig. 3 .

Eupanopeus americanus Rathbun, 1898: 273 ; Rathbun, 1900: 140; Rathbun, 1901: 29.

3.1.1. Type material

Syntype. Guadeloupe: 1 male, MHNG 16422 (Mus´eum d’ histoire Naturelle de Gen`eve), Caribbean Sea, 1857 (accessed) .

3.1.2. Material examined

Brazil: Para´: 1 male (CW 19.2 mm), CCDB 4446 , Salin´opolis, 0 ◦ 36’49.24"S, 47 ◦ 20’35.36"W, 15.xi.2012 ; 4 male (CW 15.3 mm, 15.5 mm, 19.2 mm and 21.3 mm) and 1 female (CW 16.2 mm), CCDB 4445 , S˜ao Joao ˜de Pirabas, 0 ◦ 46’1.21"S, 47 ◦ 10’12.4"W, 16.xi.2012 . – Maranh˜ao : 1 male (CW 23.2 mm), CCDB 6755 , S˜ao Jose´de Ribamar, 2 ◦ 27’29’’S, 44 ◦ 09’17’’W, 11.xii.2019 ; 3 female (CW 17.8 mm, 21.2 mm, 21.9 mm), CCDB 6756 , S˜ao Jose´de Ribamar, 02 ◦ 30’31"S, 44 ◦ 01’42"W, 06.xii.2019 ; 5 male (CW 12.5 mm, 13.4 mm, 14.1 mm, 16.8 mm and 22.6 mm) and 1 female (CW 7.3 mm), CCDB 6602 , S˜ao Jose´de Ribamar, 02 ◦ 36’53"S, 44 ◦ 06’23"W, 10.xii.2019 ; 3 male (LC 20.5 mm, 21.3 mm and 23.4 mm), CCDB 6670 , S˜ao Jose´de Ribamar, 02 ◦ 30’31"S, 44 ◦ 01’42"W, 06.xii.2019 . – Espírito Santo: 1 female (CW 6.8 mm), CCDB 2257 , Guarapari, 04.xi.2006 . – Rio de Janeiro: 1 male (CW 9.5 mm), CCDB 7158 , Búzios, 20.v.2015 ; 2 male (CW 11.2 mm and 17.8 mm) and 1 female (CW 18.2 mm), CCDB 2227 , Paraty, 23 ◦ 12’52.5’’S, 44 ◦ 42’44.3’’W, 17.viii.2007 . – S˜ao Paulo: 1 male (CW 23.7 mm), CCDB 3278 , Ubatuba, 23 ◦ 27’S, 45 ◦ 02’W, 04.iv.2011 ; 1 female (CW 11.8 mm), CCDB 6384 , S˜ao Sebasti˜ao, 23 ◦ 48’78.1’’S, 45 ◦ 24’46.9’’W, 09.x.2000 ; 1 male (CW 27.2 mm), CCDB 5657 , Ubatuba, 22.iv.2012 ; 1 male (CW 17.9 mm), CCDB 1133 , S˜ao Sebasti˜ao, 23 ◦ 48’78.1’’S, 45 ◦ 24’46.9’’W, 01.xi.2001 ; 1 male (CW 31.2 mm), CCDB 2100 , S˜ao Sebasti˜ao, 23 ◦ 48’78.1’’S, 45 ◦ 24’46.9’’W, 14.viii.2007 ; 1 male (CW 18.4 mm), CCDB 1594 , S˜ao Vicente, 23 ◦ 58’33.98’’ S, 46 ◦ 22’19.6’’ W, 23.x.2011 ; 1 female (CW 18.3 mm), CCDB 6742 , Guaruja ´, 23 ◦ 54’49.8’’S, 46 ◦ 11’58.6’’W, 24.x.2011 ; 2 male (CW 17.5 mm, 17.9 mm) and 1 female (CW 8.1 mm), CCDB 992 , Ilha Comprida , 25 ◦ 01.237’S, 47 ◦ 55.075’W, 30.viii.2011 ; 1 male (CW 19.5 mm), CCDB 2442 , Cananeia, 25 ◦ 04’05,2’’S, 47 ◦ 55’36,8’’W, 29.viii.2011 ; 1 male (CW 16.8 mm), CCDB 3762 , Cananeia, 25 ◦ 01’21.9’’S, 47 ◦ 55’46.5’’W, 10.iii.2012 . – Santa Catarina: 2 female (CW 5.6 mm, 6.9 mm), CCDB 7337 , Bombinhas, 19.i.2023 .

3.1.3. Diagnosis

Front distinctly quadrilobed with prominent and rounded outer lobes. Carapace sub-hexagonal with raised, granulate, transverse striations on its dorsal surface; carapace regions not raised. In general, number of transverse striations higher than in other congeners. Anterolateral margin of carapace with five teeth; first two are separated by a deep and rounded sinus, second square-shaped tooth, larger than first; third similar to preceding, but with external margin nearly straight; fourth with right external angle and fifth acute. Distinctly raised transverse ridge along midline of last two anterolateral teeth. Carpus of chelipeds with groove parallel to distal margin and fine granulation, external surface smooth to naked eye. Pigmented spot on inner surface of third maxilliped ischium absent. Width of pleonite 6 at the distal end similar to its width at the proximal end; length:width ratio of pleonite 6 greater than 0.70; socket of pleonal locking mechanism not reaching the half of pleonite 6. Typical trilobed gonopod apex of Panopeus absent. Lateral tooth of first gonopod simple and minute. Vulva more than half the length of the sternite 6; vulva with reniform shape.

3.1.4. Distribution

Western Atlantic – United States (Florida), Antilles, north of South America and Brazil (Par´a, Maranh˜ao, Rio Grande do Norte, Paraíba, Pernambuco, Sergipe, Alagoas, Bahia, Espírito Santo, Rio de Janeiro, S˜ao Paulo, Paran´a, Santa Catarina, Rio Grande do Sul) ( Masunari et al., 1998; Nalesso et al., 2005; Melo, 2008; Marochi and Masunari, 2011; Mantelatto et al., 2020).

3.1.5. Remarks

Our results followed the previous morphological and genetic studies that already suggested this species is consistently different from the other Panopeus species ( Thoma et al., 2014; Mendoza et al., 2022). The absence of the trilobed gonopod apex, which is a key character for the genus, is a strong indicator that this species is not part of Panopeus (see Results and Discussion).

Figures

Fig. 1. Genus Panopeus H. Milne Edwards, 1834. (A) Panopeus americanus Saussure, 1857 (CCDB 2227; CW = 17.8 mm), Rio de Janeiro, Brazil. (B) Panopeus austrobesus Williams, 1983 (CCDB 2240; CW = 13.4 mm), Espírito Santo, Brazil. (C) Panopeus harttii Smith, 1869 (CCDB 2347; CW = 16.1 mm), Cear´a, Brazil. (D) Panopeus lacustris Desbonne in Desbonne & Schramm, 1867 (CCDB 3554; CW =15.3 mm), Bocas del Toro, Panama. (E) Panopeus meridionalis Williams, 1983 (CCDB 6678; CW = 28.5 mm), Maldonado, Uruguay. (F) Panopeus occidentalis Saussure, 1857 (CCDB 2337; CW = 17.8 mm), Cear´a, Brazil. (G) Panopeus rugosus A. Milne-Edwards, 1880 (CCDB 6411; CW = 49.3 mm), S˜ao Paulo, Brazil. Scale bars (mm): A = 8.9; B = 6.7; C = 8; D = 7.6; E = 14.2; F = 4.5; G = 24.6.

Fig. 4. Panopeus americanus Saussure, 1857. A, D, E = syntype male (MHNG 16422), Guadeloupe; B, C, F–H, L-N = male (CCDB 2227; CW = 17.8 mm), Rio de Janeiro, Brazil; I =male (CCDB 4445; CW =21.3 mm), Par´a, Brazil; J =male (CCDB 6602; CW =22.6 mm), Maranh˜ao, Brazil; K =female (CCDB 2227; CW =18.2 mm), Rio de Janeiro, Brazil. (A) General dorsal view of Panopeus americanus syntype. (B, D) Front, dorsal view. (C, E) Anterolateral margin of the carapace, dorsal view. (F) Cheliped, outer view. (G) Third maxilliped, view of the inner surface. (H) Fourth pereopod, lateral view. (I) G1 apex, mesial lateral view (coloured image was generated on a stereomicroscope; grayscale image was produced on a CT-scan equipment). (J) Carapace, dorsal view. (K) Right vulva. (L) Carapace, frontal view. Blue arrow indicates the carpal groove. (M) Thoracic sternum and pleon, carapace ventral view. (N) Sixth pleonite, view of the inner surface. Scale bars (mm): B, L = 2; C, F = 5.5; G, N = 2; H = 2.5; I = 0.25; J = 11; K = 0.5; L, M = 4.

Fig. 8. Panopeus meridionalis Williams, 1983. A, D, E, G-I =male (CCDB 6678; CW =28.5 mm), Maldonado, Uruguay; B, C, G, J-L =male (CCDB 6678; CW = 21.6 mm), Maldonado, Uruguay; F = female (CCDB 6678; CW = 11.7 mm), Maldonado, Uruguay. (A) Carapace, dorsal view. (B) Sixth pleonite, view of the external surface. (C) Sixth pleonite, view of the inner surface. (D) G1 apex, mesial lateral view (generated on a stereomicroscope). (E) Third maxilliped, view of the inner surface. (F) Right vulva. (G) Carapace, frontal view. (H) Cheliped, outer view. (I) Front, dorsal view. (J) Anterolateral margin of the carapace, dorsal view. (K) Fourth pereopod, lateral view. (L) Sternites 3 and 4, ventral view. White arrow indicates the pigmented spot on the third maxilliped. Scale bars (mm): A =14; B, C, K =4; D = 0.25; E = 3; F = 0.25; G, H = 7; I = 2; J, L = 5.5.

Fig. 3. Illustrated morphological guide for Panopeus diagnostic characters. (A) Carapace in dorsal view with anterolateral teeth and transverse granulate striations. (B) Lateral view of the carpus, propodus and dactyl of right cheliped. (C) Inner surface of third maxilliped. (D) Mesial lateral view of right gonopod with the trilobed apex. Abbreviations: alt, anterolateral tooth; ap, accessory process; cc, carpus of cheliped; cg, carpal groove; dc, dactyl of cheliped; fr, front; itm, ischium of third maxilliped; lt, lateral tooth; mp, median process; msf, median sinus of the front; mtm, merus of third maxilliped; pc, propodus of cheliped; pg, propodal groove; ps, pigmented spot. Scale bars (mm): A =4.5; B = 2; C = 0.25; D = 4.

Fig. 6. Panopeus harttii Smith, 1869. A =male (CCDB 5918; CW =14.3 mm), S˜ao Paulo, Brazil; B, C, E-I; K, L =male (CCDB 2347; CW =16.1 mm), Cear´a, Brazil; D =female (CCDB 5040; CW =11.74 mm), S˜ao Paulo, Brazil; J = male (CCDB 5040; CW =12.4 mm), S˜ao Paulo, Brazil. (A) General dorsal view of a Panopeus harttii specimen. (B) Front, dorsal view. (C) Sixth pleonite, view of the inner surface. (D) Right vulva. (E) Carapace, dorsal view. (F) Third maxilliped, view of the inner surface. (G) Anterolateral margin of the carapace, dorsal view. (H) Cheliped, outer view. (I) Carapace, frontal view. (J) G1 apex, mesial lateral view (coloured image was generated on a stereomicroscope; grayscale image was produced on a CT-scan equipment). (K) Fourth pereopod, lateral view. (L) Thoracic sternum and pleon, carapace ventral view. White arrow indicates the pigmented spot on the third maxilliped. Blue arrow indicates the carpal groove. Red arrow indicates the line of spines on merus. Scale bars (mm): A = 7; B, C, F = 2; D, J = 0.25; E = 8; G, I, L = 4; H = 5.5; K = 2.5.