Aglaophenia trifida L. Agassiz, 1862

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 49

Aglaophenia trifida L. Agassiz, 1862

Fig. 14d

Aglaophenia cristata McCrady, 1859: 202 [not Aglaophenia cristata ( Lamarck, 1816) = Aglaophenia pluma ( Linnaeus, 1758) ]. Aglaophenia trifida L. Agassiz, 1862: 358 .

Type locality. 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 Gosnold Station 222/276E, one colony, 8.5 cm high, without gonophores, ROMIZ B1126 .— Nearshore off Fort Pierce, 27°29.6’N, 80°17.0’W, 5–8 m, 02.v.1975, one colony, 4.5 cm high, without gonophores, coll. F. Stanton, ROMIZ B3980 .— Nearshore off Fort Pierce, 27°29.6’N, 80°17.0’W, 7–8 m, 10.vii.1975, SCUBA, one colony, 4.2 cm high, 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. trifida was applied to the species a short time later by L. Agassiz (1862). Although Agassiz neither described nor illustrated it, the specific name trifida is 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 Gulf Stream 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. rigida and nine in A. trifida . After examinating type material of A. rigida and finding nine rather than eight cusps to be present, I synonymized the two names ( Calder 1983).

Aglaophenia trifida resembles A. pluma , a European species re-described on the basis of a neotype by 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 trifida is held to be distinct here.

Nutting (1900) found Aglaophenia rigida (= A. trifida ) to be abundant along the Carolina coast south of Cape Hatteras in Albatross collections, and concluded that it was likely the most abundant species of the genus Aglaophenia Lamouroux, 1812 on the American Atlantic seaboard. Fraser’s (1912b) report of this rather large species (as A. rigida ) from Sargassum near Beaufort, North Carolina, is regarded here as a misidentification. Records of A. trifida from areas outside the southern United States need 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 ).

Figures

FIGURE 14. a, Aglaophenia dubia: part of a hydrocladium with two hydrothecae, ROMIZ B1125, scale equals 0.10 mm. b, Aglaophenia latecarinata: part of a hydrocladium with two hydrothecae, ROMIZ B1086, scale equals 0.10 mm. c, Aglaophenia rhynchocarpa: part of a hydrocladium with two hydrothecae, ROMIZ B1083, scale equals 0.10 mm. d, Aglaophenia trifida: part of a hydrocladium with three hydrothecae, ROMIZ B1086, scale equals 0.10 mm. e, Gymnangium speciosum: part of a hydrocladium with three hydrothecae, ROMIZ B1131, scale equals 0.20 mm. f, Macrorhynchia allmani: part of a hydrocladium with two hydrothecae, ROMIZ B3982, scale equals 0.10 mm. g, Macrorhynchia clarkei: part of a hydrocladium with two hydrothecae, ROMIZ B1129, scale equals 0.10 mm. h, Macrorhynchia clarkei: a single phylactogonium from a pseudocorbula, ROMIZ B1129, scale equals 0.25 mm. i, Macrorhynchia philippina: part of a hydrocladium with three hydrothecae, ROMIZ B1092. Scale equals 0.10 mm.