Aglaophenia cristata McCrady, 1859: 202 Aglaophenia cristata ( Lamarck, 1816 ) Aglaophenia pluma ( Linnaeus, 1758 ) Aglaophenia trifida L. Agassiz, 1862: 358 Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA Calder, Dale R. Zootaxa 2013 2013-05-14 3648 1 1 72 5TRH7 L. Agassiz, 1862 L. Agassiz 1862 [151,596,151,177] Hydrozoa Aglaopheniidae Aglaophenia Animalia Leptothecata 48 49 Cnidaria species trifida   Fig. 14d      Aglaophenia cristata McCrady, 1859: 202[not  Aglaophenia cristata( Lamarck, 1816)=  Aglaophenia pluma( Linnaeus, 1758)].   Aglaophenia trifidaL. Agassiz, 1862: 358.     Typelocality. USA: South Carolina, Sullivan’s Island(stranded on the beach) and Charleston( McCrady 1859: 203, as  Aglaophenia cristata).  Voucher material.  Off Sebastian Inlet, 27°51.5’N, 80°09.5’W,  26 m,  01.iii.1974, Smith-McIntyre grab, R/ V  GosnoldStation222/276E, one colony, 8.5 cmhigh, without gonophores, ROMIZ B1126.—  Nearshoreoff Fort Pierce, 27°29.6’N, 80°17.0’W,  5–8 m,  02.v.1975, one colony, 4.5 cmhigh, without gonophores, coll. F. Stanton, ROMIZ B3980.—  Nearshoreoff Fort Pierce, 27°29.6’N, 80°17.0’W,  7–8 m,  10.vii.1975, SCUBA, one colony, 4.2 cmhigh, without gonophores, coll. F. Stanton, ROMIZ B3981.   Remarks. This hydroid was first described as  Aglaophenia cristata( Lamarck, 1816)by McCrady (1859). He suspected it was distinct from that European species, now known as  Aglaophenia pluma( Linnaeus, 1758), but had no material of the eastern Atlantic form to verify his conjecture. The binomen  A. trifidawas applied to the species a short time later by L. Agassiz (1862). Although Agassiz neither described nor illustrated it, the specific name  trifidais nevertheless available from that work because a bibliographic reference to McCrady’s earlier description (ICZN Art. 12.2) was provided.   Aglaophenia rigida Allman, 1877, described from material collected during explorations of the GulfStream region by L.F. de Pourtalès, is morphologically similar to  A. trifida. The two had been distinguished by Fraser (1944)based on the number of cusps on the hydrothecal margin, with eight reported in  A. rigidaand nine in  A. trifida. After examinating typematerial of  A. rigidaand finding nine rather than eight cusps to be present, I synonymized the two names ( Calder 1983).   Aglaophenia trifidaresembles  A. pluma, a European species re-described on the basis of a neotypeby Svoboda & Cornelius (1991). Median inferior nematothecae extend a greater distance along the abcauline wall of the hydrotheca in  A. pluma, and its corbulae are shorter (usually with about 5–10 ribs instead of 12–14).  Aglaophenia trifidais held to be distinct here.  Nutting (1900)found  Aglaophenia rigida(=  A. trifida) to be abundant along the Carolina coast south of Cape Hatteras in Albatrosscollections, and concluded that it was likely the most abundant species of the genus  Aglaophenia Lamouroux, 1812on the American Atlantic seaboard. Fraser’s (1912b)report of this rather large species (as  A. rigida) from  Sargassumnear Beaufort, North Carolina, is regarded here as a misidentification. Records of  A. trifidafrom areas outside the southern United Statesneed verification.  Reported distribution.Atlantic coast of Florida. First record. Western Atlantic. North Carolina ( Nutting 1900, as  Aglaophenia rigida) to Brazil(Oliveira et al. submitted), and including the Gulf of Mexico ( Calder & Cairns 2009) and the Caribbean Sea ( Fraser 1944, as  Aglaophenia rigida). Elsewhere. Questionably reported from the eastern Pacific ( Fraser 1948, as  Aglaophenia rigida). United States of America Charleston Sullivan's Island 48 49 1 South Carolina holotype 1974-03-01 ROMIZ V Gosnold Station 26 27.858334 Off Sebastian Inlet 123 -80.15833 Gosnold Station 48 49 B1126 1 1975-05-02 ROMIZ F. Stanton 7 27.493334 Nearshore 123 -80.28333 Fort Pierce 48 49 B3980 1 1975-07-10 ROMIZ F. Stanton 8 27.493334 Nearshore 123 -80.28333 Fort Pierce 48 49 B3981 1