Panopeus occidentalis 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 : 105

3.6. Panopeus occidentalis Saussure, 1857

( Fig. 1E , 9 A-O)

Panopeus occidentalis Saussure, 1857: 502 ; Saussure, 1858: 431, pl. 1,

Fig. 6 ; Desbonne and Schramm, 1867: 29; Smith, 1869a: 279; A. Milne-Edwards, 1880: 13; A. Milne-Edwards, 1881: 310; Benedict and Rathbun, 1891: 360, pl. 20, Fig. 3 , pl. 23, Fig. 14; Rathbun, 1900: 14; Rathbun, 1930: 348, pl. 161, Figs. 1-3 ; Rathbun, 1933: 61; Williams, 1965: 198, Figs. 181, 183N; Coelho and Ramos, 1972: 190; Markham and McDermott, 1981: 1273; Abele and Kim, 1986: 51; Coelho et al., 1986: 93; Melo, 1996: 374; Schubart et al., 2000: 13; Bertini et al., 2004: 2201; Braga et al., 2005: 31, Fig. 39; Almeida et al., 2006: 15; Coelho et al., 2008: 34; Melo, 2008: 11; Ng et al., 2008: 191; Felder et al., 2009: 1082; Alves et al., 2012: 945; Thoma et al., 2014: 96; Hollier, 2018: 297; Mantelatto et al., 2020: 75.

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

Fig. 7 ; Desbonne and Schramm, 1867: 29; Smith, 1869a: 280; A. Milne-Edwards, 1880: 13; A. Milne-Edwards, 1881: 311; Benedict and Rathbun, 1891: 371, pl. 24, Figs. 3 and 4 .

Eupanopeus occidentalis Rathbun, 1898: 273 ; Rathbun, 1900: 140; Rathbun, 1901: 29; Verrill, 1908: 351, Fig. 17, pl. 16, Fig. 2 .

Eupanopeus serratus Rathbun, 1898: 273 ; Verrill, 1908: 353, Figs. 14d, 18, pl. 16, Figs. 1 and 5.

3.6.1. Type material

Syntype. Guadeloupe: 1 male, MHNG 16428 (Mus´eum d’ histoire Naturelle de Gen`eve), Caribbean Sea, 1857 (accessed) .

3.6.2. Material examined

Brazil: Maranh˜ao : 1 male (CW 18.1 mm), CCDB 6757 , S˜ao Jose´de Ribamar, 02 ◦ 30’3’’S, 44 ◦ 01’42’’W, 06.xii.2019 . – Cear´a: 1 male (CW 17.8 mm), CCDB 2337 , Fortaleza, 03 ◦ 43’25.4’’S, 38 ◦ 29’26.7’’W, 22. v.2008 . – Pernambuco: 1 male (CW 12.4 mm), CCDB 6920 , Cabo de Santo Agostinho , 08 ◦ 21’18’’S, 34 ◦ 57’14’’W, 26.vi.2018 ; 1 female (CW 16.9 mm), CCDB 7278 , Tamandar´e, 08 ◦ 41’89.06’’S, 35 ◦ 4’27.93’’W, 13. xi.2017 ; 1 male (CW 19.9 mm), CCDB 7279 , Tamandar´e, 08 ◦ 41’89.06’’S, 35 ◦ 4’27.93’’W, 04.iv.2018 ; 1 female (CW 16.1 mm), CCDB 7345 , Tamandar´e, 24.x.2018 . – Bahia: 1 male (CW 15.9 mm) and 1 female (CW 21.8 mm), MZUSP 11709 , Itamarac´a, 17.ix.1970 (uncertain locality).

3.6.3. Diagnosis

Front slightly quadrilobed with outer lobes barely visible and margin near straight. Sub-hexagonal carapace with the gastric region notably convex; medial (1M, 2M, 3M, 4M) and antero-lateral (1L, 2L, 3L, 4L, 5L) carapace regions raised, but not as disntinct as in P. harttii . Transverse granulate striations of carapace prominent. First anterolateral tooth separated by a shallow sinus from the second; three posteriors more prominent and acute than the others. Along the median line of fifth tooth there is an outstanding raised ridge. Carpus and propodus of chelipeds with smooth aspect. Carpal groove parallel to the distal margin of the segment deep, but to a lesser extent when compared to P. harttii . Dark colour of immovable finger not invading the palm. Inner surface of third maxiliped with a pigmented spot. Length:width ratio of pleonite 6 less than 0.70; socket of pleonal locking mechanism not reaching the half of pleonite 6. Trilobed structure typical of Panopeus present at the gonopod apex. Lateral tooth of first gonopod bifid. Vulva less than half the length of the sternite 6; vulva with circular shape.

3.6.4. Variations

Rathbun (1930) mentioned that some morphological characters in this species, such as the prominency of transverse granulate striations and the morphology of the second anterolateral tooth, vary considerably among the specimens. We could observe part of these variations in the material we evaluated. Second antero-lateral tooth can be either sharp and narrow or rounded and wide. Carpus of chelipeds can be rugose and propodus present a shallow carpal groove.

3.6.5. Distribution

Western Atlantic – Bermuda, United States (from North Carolina to Florida), Gulf of Mexico, Antilles, Caribbean Sea, north of South America and Brazil (Maranh˜ao, Piauí, Cear´a, Paraíba, Pernambuco, Alagoas, Bahia, Rio de Janeiro) ( Melo, 1996; Melo, 2008; Júnior et al., 2010; present study).

3.6.6. Remarks

The assessment of several individuals collected on the coast of S˜ao Paulo state and the absence of P. occidentalis specimens among this sample suggests that the previous records of this species in the state is a consequence of misidentification ( Bertini et al., 2004; Braga et al., 2005; Alves et al., 2012; Peres et al., 2018). Our results point to a more restricted area of occurrence for P. occidentalis , with a probable southern limit being between the north of the state of Rio de Janeiro and the south of Pernambuco. This evidence corroborates the data presented by Mantelatto et al. (2020) who placed the occurrence of the species on the coast of S˜ao Paulo as uncertain. Because of that we discarded the possibility of occurrence of this species on S˜ao Paulo coast and on the coast of the states in the southern region of Brazil (i.g., Paran´a, Santa Catarina and Rio Grande do Sul). The specimens of MZUSP 11709 are labelled as being collected in “Itamarac´a – Bahia ”, however, there are no coastal areas in Bahia known as Itamarac´a. Because of that we consider the origin of these specimens as uncertain.

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. 9. Panopeus occidentalis Saussure, 1857. A, B, C =syntype male (MHNG 16428), Guadeloupe; E, G; J =male (CCDB 2337; CW =17.8 mm), Cear´a, Brazil; D, F, H, I, K, M O = male (CCDB 6920; CW = 12.4 mm), Pernambuco, Brazil; L = female (CCDB 7345; CW = 16.1 mm), Pernambuco, Brazil. (A) General dorsal view of Panopeus occidentalis 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) Sixth pleonite, view of the external surface. (L) Right vulva. (M) Carapace, frontal view. (N) Sixth pleonite, view of the inner surface. (O) Sternites 3 and 4, ventral view. Blue arrows indicate the carpal groove. White arrow indicates the pigmented spot on the third maxilliped. Scale bars (mm): D, H = 1.5; E = 6; F, M = 4; G, K, N = 2; I, L = 0.25; J = 4.5; O = 3.

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.

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. 2. Map showing the Southwestern Atlantic coast and the approximate localities of the evaluated specimens.

Fig. 7. Panopeus lacustris Desbonne in Desbonne & Schramm, 1867. A-H =female (CCDB 3554; CW =15.3 mm), Bocas del Toro, Panama. (A) Carapace, dorsal view. (B) Third maxilliped, view of the inner surface. (C) Front, dorsal view. (D) Anterolateral margin of the carapace, dorsal view. (E) Cheliped, outer view. (F) Right vulva. (G) Carapace, frontal view. (H) Fourth pereopod, lateral view. White arrow indicates the pigmented spot on the third maxilliped. Scale bars (mm): A =7.5; B, H = 2; C = 1.5; D = 4; E = 5.5, F = 0.25; G = 3.

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. 5. Panopeus austrobesus Williams, 1983. A, F, I =holotype male (USNM 59462), Paran´a, Brazil; D, G, J =female (CCDB 2240; CW =13.4 mm), Espírito Santo, Brazil; B, C, E, K, M O = male (CCDB 2599; CW =23.6 mm), Bahia, Brazil; H = male (CCDB 5858; CW =26.9 mm), Pernambuco, Brazil; L =female (CCDB 2599; CW = 26.3 mm); Bahia, Brazil. (A) General dorsal view of Panopeus austrobesus holotype. (B, I) Carapace, frontal view. (C) Anterolateral margin of the carapace, dorsal view. (D) Carapace, dorsal view. (E, F) G1 apex, mesial lateral view (coloured images were generated on a stereomicroscope; grayscale image was produced on a CT-scan equipment). (G) Cheliped, outer view. (H) Third maxilliped, view of the inner surface. (J) Front, dorsal view. (K) Fourth pereopod, lateral view. (L) Right vulva. (M) Sternites 3 and 4, ventral view. (N) Sixth pleonite, view of the inner surface. (O) Sixth pleonite, view of the external surface. White arrows indicate the pigmented spot on the third maxilliped. Scale bars (mm): B = 8; C, M = 6; D = 5; E = 0.25; G, J, K = 3.5; H, N, O = 3; L = 1.