3.3. 1. Dilocarcinus septemdentatus (Herbst, 1783)

Figures 1 A, C, 2 (L 1), 5 A – E

Cancer n. 957 — Gronovius 1764: 222.

Cancer Orbicularis — Meuschen 1778: 84 (n. 788) [unavailable name, Opinion 260 (ICZN 1954 a)].

Cancer Orbicularis — Meuschen 1781: unnumbered page (n. 957) [Unavailable name, Opinion 261 (ICZN 1954 b)].

Cancer septemdentatus Herbst, 1783: 155 .

Arica septemdentata — White 1847: 31 [nomen nudum].

Dilocarcinus septemdentatus — Gerstaecker 1856: 148. — Göldi 1885: 662. — Göldi 1886: 28, pl. 2 figs 3–17. — Nobili 1896: 1 [part]. — Moreira 1901: 44, 49, 109 [part]. — Pretzmann 1968: 75 (in list). — Rodríguez 1981: 48 (in list). — Rodríguez 1992: 128. — Magalhães and Türkay 1996 a: 67 (in list) [part], 69 (in list) [part], 78 (in list) [part], 79, figs 23, 24. — Magalhães 1998: 519 (in list) [part]. — Barros and Pimentel 2001: 32 (in list). — Magalhães 2003: 203 (in key), 206, figs 108 (map), 109 a, b, e. — Collins et al. 2004: 254 (in list). — Ng et al. 2008: 187 (in list). — Magalhães and Türkay 2008: 187, figs 3, 5, 6 [part]. — Vieira 2008: 68, 69, table 5.1 (in list). — Collins et al. 2009: 50, fig. 1 a. — Collins et al. 2011: 191, Appendix (in list). — ICMBio 2014: 178. — Magalhães 2016: 431 (in list) [part].

Orthostoma septemdentatum — Ortmann 1897: 326 (in key), 327 [part].

Dilocarcinus (Dilocarcinus) septemdentatus — Bott 1969: 44, pl. 8, fig. 14 a, b, pl. 20, fig. 45.

Diagnosis.

G 1 with distal portion strongly curved laterally; subdistal lobe moderately to well developed; apex directed laterally, approximately as long as the subdistal lobe.

Description (amended from Magalhães and Türkay 2008).

Carapace (Fig. 5 A) smooth, strongly convex longitudinally; frontal margin unarmed, distinctly bilobed; anterolateral margins with 6–7 acute teeth behind exorbital tooth. Pleonal somites (Fig. 5 B) III – VI fused; somite III smooth, without transversal carina along anterior margin. G 1 (Fig. 5 C – E) with distal portion strongly bent laterally; lateral border (“ lb ” in Fig. 5) gently sinuous, with few minute setae medially and dense patch of long setae along basal portion; marginal suture (“ ms ” in Fig. 5) running along mesial surface, twisted towards lateral side near apex (“ a ” in Figs 1, 5); lateroventral side with distinct, moderately to well-developed rounded subdistal lobe (“ sl ” in Figs 1, 5 C); field of short spines (“ fs ” in Fig. 5) continuous, located subterminally on lateroventral side, denser along and extending distally to dorsal surface; subapical bristles, when present, in small number; apex strongly bent laterally, flat, narrow, approximately as long as subdistal lobe; distal aperture (“ do ” in Fig. 5) very narrow, slit-like, directed laterally.

Type material.

Neotype (designated herein): Male (cw 47.9, cl 37.6), MZUSP 44534, Brazil, Pará, municipality of Peixe-Boi, braços do rio Peixe-Boi, 01 ° 11 ′ 31 ″ S 47 ° 18 ′ 44 ″ W, 34 m altitude, III. 1994, E. Matos.

Type locality.

Brazil, state of Pará, municipality of Peixe-Boi, Peixe-Boi River.

Material examined (herein confirmed as Dilocarcinus septemdentatus).

SURINAME — • 1 ♂, NHM 1959.3. 20.6, 1838, I. T. Sandersen. — Paramaribo District: • 2 ♂ (cw 48.2, cl 37.8; cw 48.7, cl 39.9), ZMB 12981, near Paramaribo, C. Heller. — Saramacca District : • 1 ♂, RMNH D 20711, near Granmankanare, Saramacca River, 7. iv. 1964, M. Boeseman. — Brokopondo District : • 2 ♂, NHM 1959.3. 20.7-8, near Donderberg [= Donder Bari Berg, 05 ° 09 ′ 50 ″ N 55 ° 15 ′ 07 ″ W], about 91.5 Km S. of Paramaribo, 4. xi. 1938, I. T. Sanderson. — Sipaliwini District : • 2 ♂ (cw 37.2, cl 30.8) 1 ♀ (cw 25.8, cl 22.5), RMNH D 20710, Suriname River, Kasi-kriki near Pokigron, 20. iii. 1964, M. Boeseman • 1 ♂ (cw 35.5, cl 28.8), RMNH D 21790, Ligorio, 03 ° 54 ′ 22 ″ N 55 ° 33 ′ 59 ″ W, 16. vi. 1965, G. F. Mees • 1 ♂ (cw 32.6, cl 27.6), RMNH ZMA. Crust. D. 102298, near Ligorio, 27. i. 1967, H. Nijssen . BRAZIL — Amapá: • 1 ♂ (cw 50.5, cl 39.5), IEPA 255, furo do Araguari, arquipélago do Bailique, Macapá, 9. iv. 2000, I. M. Vieira, O. A. Alencar, O. M. Costa, J. Cardoso and A. C. Souza — Pará : • 1 ♂ (cw 36.1, cl 29.8), RMNH D 12187, Apisiké [tributary creek of upper West Paru River], 20. iv. 1952, D. C. Geijkes • 1 ♂ (cw 51.3, cl 39.7), SMF 2718, Quatipuru, campo Santarém, 06. iv. 1963, E. - J. Fittkau • 1 ♂ (cw 44.8, cl 35.3), MZUSP 11694, municipality of Peixe-Boi, braços do rio Peixe-Boi, 01 ° 11 ′ 31 ″ S 47 ° 18 ′ 44 ″ W, 34 m altitude, iii. 1994, E. Matos col. — Amazonas : • 2 ♂♂ (cw 41.2, cl 30.7; cw 49.1, cl 36.9), INPA 805, rio Solimões, Tefé, Reserva de Desenvolvimento Sustentável de Mamirauá, 26. iv. 1994, P. Henderson • 2 ♂♂ (cw 20.5, cl 16.2; cw 44.5, cl 33.3) 1 ♀ (cw 13.4, cl 10.4), INPA 802, rio Solimões, Tefé, Reserva de Desenvolvimento Sustentável de Mamirauá, xii. 1993 ; 1 ♂ (cw 46.7, cl 36.1), INPA 796, Iranduba, rio Solimões, ponta do Catalão, lago do Pirapora, 03 ° 11 ′ S 59 ° 55 ′ W, ix. 1999, L. Rapp Py-Daniel et al . • 1 ♂ (cw 42.2, cl 31.9), INPA 1255, Iranduba, rio Solimões, ponta do Catalão, lago do Pirapora, braço do paraná do Ximborena, 03 ° 11 ′ S 59 ° 55 ′ W, 24. v. 2000, L. Rapp Py-Daniel et al . • 1 ♂ (cw 44.9, cl 35.1), SMF 29878, Iranduba, rio Solimões, ponta do Catalão, lago do Pirapora, 03 ° 09 ′ 07 ″ S 59 ° 54 ′ 50 ″ W, 13. vii. 2000, L Rapp Py-Daniel et al . • 1 ♂ (cw 47.2, cl 36.7), INPA 1301, rio Amazonas, lago Coró-Coró, 03 ° 13 ′ 50.5 ″ S 58 ° 41 ′ 28.7 ″ W, 7. vii. 2000, A. Varella • 1 ♂ (cw 47.7, cl 36.9) 1 ♀ (cw 31.7, cl 25.6), INPA 151, lago Janauacá, rio Solimões, 8. viii. 1985, G. M. Soares • 1 ♀ (cw 12.9, cl 9.9), NHMW 6632, lago Janauacá, v. 1971, U. Irmler • 1 ♂ (cw 41.5, cl 31.0) 1 ♀ (cw 43.2, cl 34.8), INPA 1470, Carauari, Reserva Extrativista (Resex) Médio-Juruá, comunidade Nova Esperança, 05 ° 05 ′ 31 ″ S 67 ° 10 ′ 03 ″ W, 27. vi. – 16. vii. 2005, F. Xavier Filho and A. L. Henriques • 14 ♂♂ (cw 11.1, cl 9.4 – cw 44.2, cl 37.0) 7 ♀♀ (cw 19.4, cl 16.1 – cw 34.1, cl 27.4), INPA 800, rio Juruá, lago do Rato / Caroçal, Carauari, 05 ° 43 ′ 02.4 ″ S 67 ° 42 ′ 12.8 ″ W, 6. iv. 2000, J. Zuanon • 1 ♀ (MZUSP 4770), Pauini, 07 ° 40 ′ S 66 ° 58 ′ W, 19. xii. 1974, P. Vanzolini .

Additional material examined (see Remarks below; herein considered as not belonging to Dilocarcinus septemdentatus).

Dilocarcinus pagei Stimpson, 1861: • 7 ♀♀ (cw 36.5, cl 30.7 – 45.7: 38.9), ZSM 1089-4, Brazil, Pará, ilha do Marajó, L. Müller ; • 1 ♂ (cw 51.2, cl 40.3 mm), 2 ♂♂ (cw 34.2, cl 27.6; cw 50.9, cl 41.3) 4 ♀♀ (cw 43.3, cl 35.0 – cw 46.7, cl 36.6), MZUT Cr 291, Brazil, Mato Grosso, Carandasinho [= Carandazinho], 1899, Dr. A. Borelli • 1 ♀, dry, NHM 1955.2. 21.24 (ex- MZUT), idem; RMNH D- 11126, Bolivia, Beni, río Yacuma, near Espiritu, 13–28. iv. 1954, W. Forster and O. Schindler • 2 ♂♂ 2 ♀♀ (MZUT Cr 293), Paraguay, Concepción, Colonia Risso, 1893, Dr. A. Borelli • 5 ♂♂ (cw 16.7, cl 12.7 – cw?, cl?), 8 ♀♀ (cw 12.5, cl 10.4 – cw?, cl?) [in bad condition], MZUT Cr 289, Argentina, Chaco, Resistencia, 1893, Dr. A. Borelli. — Poppiana argentiniana (Rathbun, 1905): • 3 ♂♂ (cw?, cl? – cw 28.5, cl 23.5), MZUT Cr 289, Argentina, Chaco, Resistencia, 1893, Dr. A. Borelli .

Distribution.

Northern South America, in the central and lower Amazon basin as well as in coastal river basins in Suriname and Brazil (Fig. 6 A) (Magalhães and Türkay 2008; present paper).

Remarks.

Herbst’s (1783) specimen used to describe D. septemdentatus could not be found in the ZMB ’ s holdings despite the efforts of Sakai (1999) and Magalhães and Türkay (2008). One of us (C. M.) made a last attempt to locate the specimen on a visit to the ZMB on 4 th October 2023, but this search was equally unsuccessful. Thus, considering that: (a) the name-bearing type specimen can be considered not extant; (b) the three species of Dilocarcinus studied herein are sympatric (and can be even syntopic); and (c) the original description of D. septemdentatus was based on somatic characters of a single female specimen, with insufficient morphological resolution, it seems essential to designate a neotype in order to define the present taxon objectively (ICZN 1999: Art. 75).

Herbst (1783) did not specify the exact provenance of his specimen; he just mentioned it was from American coastal waters. Bott (1969) restricted the type locality to the lower Amazon (Brazil, state of Pará, surroundings of Belém) but without further explanation. The neotype specimen (MZUSP 44534) was therefore chosen from specimens collected about 150 km northeast of Belém, in a coastal river basin from the state of Pará, northern Brazil.

Nobili (1896: 1; 1898: 9) examined specimens collected by Dr. Borelli from Colonia Risso (río Apa, upper río Paraguay) and Resistencia (province Chaco, Argentina) preserved in the “ R. Museo Zoologico di Torino ” (currently Museo Regionale di Scienze Naturali di Torino, Sezione di Zoologia) and assigned them, respectively, to Dilocarcinus septemdentatus and Orthostoma septemdentatum . Colosi (1920: 15), in addition to this material, also examined specimens from Carandasinho (state of Mato Grosso, Brazil) and treated them as Trichodactylus (Dilocarcinus) orbicularis . These lots have been reexamined by one of us (C. M.) in November 1988 on a visit to the MZUT and the specimens were found to be Dilocarcinus pagei Stimpson, 1861 and Poppiana argentiniana (Rathbun, 1905) (see above). Rathbun (1906: 58) and Balss (1914: 409) listed D. septemdentatus as a junior synonym of Trichodactylus (Dilocarcinus) orbicularis but the specimens they have dealt with actually belong to D. pagei . The specimen from Bolivia (rio Yacuma) treated by Holthuis (1959: 218) as Trichodactylus (Dilocarcinus) septemdentatus is also D. pagei (C. M., pers. observation).