acus, Sphyraena Lacepède [B. G. E.] (ex Plumier) 1803:325, 327, Pl. 1 (fig. 3) [Histoire naturelle des poissons (Lacepède) v. 5; ref. 4930] Martinique Island or West Indies, western Atlantic. No types known. Type catalog: Collette et al. 1997:23 [ref. 22813]. Based on a Plumier drawing. Placed on Official Index in Opinion 900 [ref. 13280] (1970); suppressed for purpose of priority but not for homonymy. This name would then be regarded as a synonym of Tylosurus imperialis (Rafinesque 1810) following ICZN Opinion 900, but that has not been followed by subsequent authors since 1965; in the interest of stability, continued usage of acus was recommended (see Collette & 2003:10 [ref. 27306]). But Opinion 2169 (in 2007) reinstated acus as a valid name -- see Collette & Parin 2005:232 [ref. 28549]. Five subspecies are recognized following Collette & Parin 1970: T. a. acus (Lacepède 1803) in the western Atlantic, T. a. imperialis (Rafinesque 1810) in the Mediterranean Sea, T. a. rafale Collette and Parin 1970 in the Gulf of Guinea, T. a. melanotus (Bleeker 1850) throughout the Indo-west Pacific and extending into the eastern Pacific, and T. a. pacificus (Steindachner 1876) in the eastern Pacific; the latter was subsequently raised to species level by Collette & Banford (2001 [ref. 25982]). •Valid as Esox acus (Lacepède 1803) -- (Herrera 1896:31 [ref. 39336]). •Valid as Tylosurus acus subspecies acus (Lacepède 1803) -- (Smith-Vaniz et al. 1999:166 [ref. 25013], Collette & Banford 2001:51 [ref. 25982], Collette et al. 2003:102 [ref. 26784], Collette 2003:1112 [ref. 26981], Collette 2003:9, 10 [ref. 27306], Paxton et al. 2006:718 [ref. 28995], Allen & Erdmann 2012:165 [ref. 31980], Page et al. 2013:103 [ref. 32708], Smith-Vaniz & Jelks 2014:32 [ref. 33341], Psomadakis et al. 2015:176 [ref. 34104]). •Valid as Tylosurus acus (Lacepède 1803) -- (Collette & Berry 1965:391 [ref. 13367], Parin 1967:52 [ref. 10272], Collette & Parin 1970:41 [ref. 7415], Parin 1973:260 [ref. 7191], Dor 1984:65 [ref. 29757], Collette & Parin in Whitehead et al. 1986:608 [ref. 13676], Robins & Ray 1986:106 [ref. 23100], Paxton et al. 1989:343 [ref. 12442], Cervigón 1991:227 [ref. 24472], Boschung 1992:84 [ref. 23239], Cervigón 1992:270 [ref. 23827], Paugy in Lévêque et al. 1992:584 [ref. 21590], Goren & Dor 1994:16 [ref. 25356], Randall 1995:87 [ref. 22896], Santos et al. 1997:126 [ref. 23531], Larson & Williams 1997:350 [ref. 23967], De La Cruz Agüero et al. 1997:69 [ref. 24545], Grove & Lavenberg 1997:268 [ref. 24023], Arruda 1997:62 [ref. 24952], McEachran & Fechhelm 1998:939 [ref. 23897], Chirichigno F. & Vélez D. 1998:104 [ref. 24555], Castro-Aguirre et al. 1999:206 [ref. 24550], Johnson 1999:724 [ref. 25471], Menezes & Figueiredo in Menezes et al. 2003:67 [ref. 27192], Nelson et al. 2004:99 [ref. 27807], Golani 2005:29 [ref. 37112], Vaske et al. 2005:77 [ref. 36155], Randall 2007:138 [ref. 30952] with subspecies, Fricke 2008:22 [ref. 30182], Larson et al. 2013:65 [ref. 32988], Collette 2016:2126 [ref. 34601], Carneiro et al. 2019:199 [ref. 37250], Collette & Bemis 2019:42 [ref. 37342], Reiner 2019:131 [ref. 38139], Kovačić et al. 2020:30 [ref. 37519], Psomadakis et al. 2020:336 [ref. 37272], Caires et al. in Marceniuk et al. 2021:319 [ref. 38945], Golani 2021:31 [ref. 38303], Collette 2022:379 [ref. 39718], Carvalho-Filho 2023:92 [ref. 40480], Hoff et al. 2023:6 [ref. 40463], Martínez-Servín et al. 2023:111 [ref. 40726], Page et al. 2023:149 [ref. 40505], Allen & Erdmann 2024:182 [ref. 40796]). Current status: Valid as Tylosurus acus (Lacepède 1803). Belonidae. Distribution: Circumglobal in tropical seas, except eastern Pacific. Some authors recognize 4 subspecies; acus acus occurs in the western Atlantic. Habitat: marine.