Synthecium tubithecum ( Allman, 1877 )

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141 : 30-31

Synthecium tubithecum ( Allman, 1877)

Fig. 6f

Sertularia tubitheca Allman, 1877: 24 , pl. 16, figs. 5, 6.

Synthecium tubithecum .— Nutting, 1904: 134.— Leloup, 1935a: 33.— Fraser, 1943: 91.

Synthecium nanum Fraser, 1943: 80 , 91, pl. 18, fig. 10.

Type locality. USA: Florida, Dry Tortugas, 16 ftm (29 m) ( Allman 1877: 24) .

Material examined. Southwest Florida Shelf, middle shelf west of North Naples, 26°16.83’N, 83°23.81’W, 59.5 m, 19 July 1981, triangle dredge, one colony fragment, 6 mm high, without gonophores, coll. Continental Shelf Associates, ROMIZ B1929.

Remarks. Originally described by Allman (1877) from material collected near the Dry Tortugas, Florida, Synthecium tubithecum has been reported several times since then from the Southwest Florida Shelf ( Nutting 1904; Leloup 1935 a, Fraser 1943; this study). An essentially tropical species with a wide distribution in the Caribbean Sea, its known geographic range extends as far north as the Carolinas ( Wenner et al. 1984) and Bermuda (Calder 1990 [1991a]), and as far south as Brazil ( Oliveira et al. 2016). While the reported bathymetric range of S. tubithecum is wide (1–505 m; see below), it is regarded here as a typically neritic species found most often at depths of less than 100 m ( Fraser 1944; Vervoort 1968; Reported Distribution section below).

A taxonomic and nomenclatural account of this hydroid has been provided elsewhere (Calder 1990 [1991a]). Its cnidome, comprising small microbasic mastigophores (6.3–6.6 long × 1.8–2.0 μm wide) and large (?) macrobasic mastigophores (40.0–42.5 long × 10.7–11.5 μm wide), has been described by Galea (2010).

Reported distribution. Gulf coast of Florida. Dry Tortugas, 16 ftm (29 m) ( Allman 1877: 24, as Sertularia tubitheca ).—W of Gasparilla Island, 26°47’30”N, 83°25’15”W, 28 ftm (48 m) ( Nutting 1904: 135).—SW Florida Shelf, 26°N, 82°57’30”W, 24 ftm (44 m) ( Nutting 1904: 135).—N of the Dry Tortugas, 25°04’30”N, 82°59’15”W, 26 ftm (48 m) ( Nutting 1904: 135).—Dry Tortugas ( Leloup 1935a: 33).—West of Florida, 20 ftm (37 m) ( Fraser 1943: 91).—W of the Dry Tortugas, 24°36’40”N, 83°02’20”W, 16 ftm (29 m) ( Fraser 1943: 91, as Synthecium nanum ).

Elsewhere in western North Atlantic. Barbados: 76 ftm (139 m) ( Fewkes 1881a: 128, as Sertularia tubitheca ).— Cuba: off Morro Castle, 100–250 ftm (183–457 m) ( Nutting 1895: 88, as Sertularia tubitheca ).— Anguilla: 70–200 ftm (128–366 m) ( Jäderholm 1903: 291).— USA: South Carolina, E of Bulls Bay, 32°55’N, 77°54’W, 79 ftm (144 m) ( Nutting 1904: 135).— Cuba: off Havana, 23°10’31”N, 82°19’55”W, 114 ftm (208 m) ( Nutting 1904: 135).— Cuba, near Havana, ( Nutting 1904: 135, as Synthecium rectum ).— USA: Georgia, continental slope, 31°26’N, 77°07’W, 276 ftm (505 m) ( Nutting 1904: 135, as Synthecium rectum ).— Barbados ( Nutting 1919: 115, as Synthecium tubulifera ).— Puerto Rico: off north coast, 18°31’N, 66°10’15”W, 38 ftm (69 m) + 18°30’N, 66°12’20”W, 46–56 ftm (84–102 m) + 18°30’30”N, 66°23’05”W, 40 ftm (73 m) + off west coast, 18°14’30”N, 67°25’30”W, 20–40 ftm (37–73 m) ( Fraser 1944: 237).— USA: Georgia, mid-continental shelf E of Savannah, 32°03’N, 79°49’30”W, 14 ftm (26 m) ( Fraser 1945: 21).— Colombia: 2 miles (3 km) SW of Cabo de la Vela, 21–22 ftm (38–40 m) ( Fraser 1947b: 10, as Synthecium (?) nanum ).— Virgin Islands of the United States: St. Thomas, Sound + Savannah Passage ( Vervoort 1968: 30, as Synthecium tubitheca ).— Colombia: off Santa Marta ( Wedler 1975: 332).— USA: South Carolina and Georgia, inner to outer continental shelf ( Wenner et al. 1983: 181; 1984: 21, 40, as Synthecium tubitheca ).— Colombia: vicinity of Bahía de Cartagena ( Flórez González 1983: 123).— Bermuda: 2 km SE of Castle Roads, 60–90 m + Castle Grotto, Castle Harbour, 1 m (Calder 1990 [1991a]: 84).— Cuba: north coast ( Ortiz Rosado 2000: 88).— Bermuda: Challenger Bank + Argus (=Plantagenet) Bank ( Calder 2000:1133).— Panama: Bocas del Toro area, Cayos Zapotilla, 09°15.564’N, 82°02.750’W, 7-8 m ( Calder & Kirkendale 2005: 484).—French Lesser Antilles: Guadeloupe, Grande-Terre, Grotte aux Barracudas, 16°27.343’N, 61°32.244’W, 21 m + Pointe Plate, 16°27.220’N, 61°32.128’W + Les Ancres, 16°27.002’N, 61°32.320’W, 15–18 m ( Galea 2010: 23, 24).— Cuba: Golfo de Batabanó, Punta Francés, reef, 10 m ( Castellanos-Iglesias et al. 2011: 23).— USA: Florida, east coast, 1.2 km off Palm Beach, 29 m ( Calder 2013: 34).—French Lesser Antilles: Martinique ( Galea 2013: 50).—Caribbean Sea ( Wedler 2017b: 141, figs. 159–161).— Mexico: Alacranes Reef, on stony corals (Mendoza- Becerril et al. 2018b: 130).

Figures

FIGURE 6. a, Acryptolaria longitheca: part of colony with two hydrothecae, Southwest Florida Shelf, ROMIZ B1902. Scale equals 0.2 mm. b, Acryptolaria longitheca: two gonothecae from a coppinia, Southwest Florida Shelf, ROMIZ B1902. Scale equals 0.1 mm. c, Acryptolaria tortugasensis: part of colony with three hydrothecae, Southwest Florida Shelf, ROMIZ B1906. Scale equals 0.2 mm. d, Acryptolaria tortugasensis: part of colony with a hydrotheca, Southwest Florida Shelf, ROMIZ B1906. Scale equals 0.1 mm. e, Lafoea coalescens: part of colony with four hydrothecae, Southwest Florida Shelf, ROMIZ B1915. Scale equals 0.2 mm. f, Synthecium tubithecum: part of colony with two hydrothecal pairs, Southwest Florida Shelf, ROMIZ B1929. Scale equals 0.2 mm. g, Zygophylax convallaria: part of colony with four hydrothecae, Southwest Florida Shelf, ROMIZ B1921. Scale equals 0.2 mm. h, Zygophylax convallaria: part of colony with a hydrotheca, Southwest Florida Shelf, ROMIZ B1921. Scale equals 0.1 mm. i, Zygophylax convallaria: nematophorous ramule, Southwest Florida Shelf, ROMIZ B1921. Scale equals 0.1 mm. j, Zygophylax convallaria: gonotheca, Southwest Florida Shelf, ROMIZ B1921. Scale equals 0.1 mm.