Nutting, 1900: 72 Wallace, 1909: 137 Plumularia margaretta Joyce, 1961: 70 Shier, 1965: 64 On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA Calder, Dale R. Zootaxa 2019 2019-10-25 4689 1 1 141 8LF4B Nutting, 1900 Nutting 1900 [151,606,873,900] Hydrozoa Plumulariidae Monotheca CoL Animalia Leptothecata 107 108 Cnidaria species margaretta   Fig. 24a     Monotheca margaretta  Nutting, 1900: 72, pl. 11, figs. 1–3.—  Wallace, 1909: 137.    Plumularia margaretta.—  Joyce, 1961: 70, pl. 18, figs. 1, 2.—  Shier, 1965: 64, pl. 35.     Typelocality. Bahamas: near Little Cat Island, shallow water ( Nutting 1900: 72).  Material examined.Florida Keys, Bahia Honda Channel, 24°39.489’N, 81°17.198’W, 6 m, 16 June 2008, on  Lytocarpia tridentata, one colony, 4 mmhigh, without gonophores, ROMIZB4397.—  Sanibel Island, beach at Lighthouse Point, 26°26’57”N, 82°01’06”W, on detached  Thalassiain water along shore, 24°C, 35‰,  03 April 2018, fragments of one colony, 4 mmhigh, without gonothecae, coll. D. Calder, ROMIZ B4398.   Remarks. The genus  Monotheca Nutting, 1900has been regarded as congeneric with  Plumularia Lamarck, 1816in some works, and as valid in others (Calder 1997: 10). While the genus as presently constituted may be polyphyletic, so too is  Plumularia( Moura et al. 2008: 98). Herein, certain constituent species sometimes assigned to  Monothecaare considered sufficiently unique morphologically to be recognized as generically discrete. Molecular studies provide evidence in support of that conclusion. Phylograms such as those of Leclère et al. (2007, 2009), Moura et al. (2008), and Maronna et al. (2016)reveal that  Monotheca margaretta Nutting, 1900, typespecies of  Monotheca, is clearly divergent genetically from  Plumularia setacea( Linnaeus, 1758), typespecies of  Plumularia. While a re-definition and revision of the genus appear necessary, its validity is upheld here. The present species is therefore retained in this work under the binomen  M. margaretta.   Monotheca margarettais predominantly a hydroid of near-surface waters, and a species of tropical and warmtemperate waters. From collection records listed below, it is especially frequent in beds of the seagrass  Thalassiaand on algae including detached  Turbinaria. It is also a constituent of the hydroid assemblage found on pelagic  Sargassumin the open North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. Dispersal of the species has likely been facilitated by rafting on such substrates. While best known from shallow depths, the hydroid has also been found on bottoms as deep as  73 m.Other than its transport to relatively high latitudes on pelagic  Sargassumin the Gulf Stream and North Atlantic Current, the known geographic range of  M. margarettain the western Atlantic extends from South Carolina ( Wenner et al. 1984) and Bermuda(Calder 1997) to the southern Caribbean Sea ( Van Gemerden-Hoogeveen 1965), and southwards to Brazil( Oliveira et al. 2016). The species is amphi-Atlantic in distribution, having been reported from locations on the eastern side of the ocean including the Azores, the Canary Islands, the Strait of Gibraltar, the Mediterranean Sea, Senegal, and Ghana( Ansín Agís et al. 2001). While this hydroid was collected in shelf waters off South Carolina by Wenner et al. (1984), it was never found in estuaries of the state during eight years of field work ( Calder & Hester 1978; Calder 1983). Detailed taxonomic accounts of  M. margarettainclude those of Calder (1997) and Ansín Agís et al.(2001). Gonophores of this species are thought to be fixed sporosacs, although those of a closely related species from Europe,  M. obliqua( Johnston, 1847), are liberated as very short-lived medusoids ( Motz-Kossowska 1907). The typeof gonophore produced by  M. margarettathus needs to be determined.  Reported distribution. Gulf coast of Florida.Dry Tortugas( Wallace 1909: 137).—Seahorse Key, on  Thalassia( Joyce 1961: 70, as  Plumularia margaretta).—Cape San Blas area, on  Thalassia( Shier 1965: 64, as  Plumularia margaretta).  Elsewhere in western North Atlantic. Bahamas: near Little Cat Island, shallow water ( Nutting 1900: 72).— USA: North Carolina, off Bogue Bank, on floating  Sargassum( Fraser 1912b: 381).— Bermuda: Challenger Bank, on  Campanularia insignis(=  Thyroscyphus marginatus), 55 m( Stechow 1912: 361).— Bermuda: on floating  Sargassum( Bennitt 1922: 254).— Bonaire: Boca Washikemba, on stranded algae + Lagoen, north coast, on stranded  Sargassum( Leloup 1935a: 54, as  Plumularia margaretta).— Curaçao: Boca Grandi, on drifting  Sargassum( Leloup 1935a: 54, as  Plumularia margaretta).— Aruba: Boca Prins, on stranded  Sargassum( Leloup 1935a: 54, as  Plumularia margaretta).—Atlantic Ocean: Gulf Stream, on pelagic  Sargassum+ Sargasso Sea, on pelagic  Sargassum(Burkenroad, in Parr 1939: 23).—Sargasso Sea: on  Sargassum, 34°25’N, 40°05’W+ 30°50’N, 54°35’W( Timmermann 1932: 298, 300).— Dominican Republic: Monte Cristi, on  Sargassum( Timmermann 1932: 299).— USA: Massachusetts, Gulf Stream off Martha’s Vineyard, 39°58’N, 70°06’W, on floating  Sargassum( Fraser 1944: 349, as  Plumularia margaretta).— Puerto Rico, northeast coast, 18°23’35”N, 65°37’10”W, 10 ftm ( 18 m) + 18°24’30”N, 65°38’30”W, 9 ftm ( 16 m) ( Fraser 1944: 349, as  Plumularia margaretta).— Puerto Rico: off CulebraIsland, 18°19’10”N, 65°19’40”W, 10 ftm ( 18 m) ( Fraser 1944: 349, as  Plumularia margaretta).— Colombia: 2 miles( 3 km) off Bahía Honda, 9 ftm ( 16 m) ( Fraser 1947b: 14, as  Plumularia margaretta).—Unstated location: on buoys ( Woods Hole Oceanographic Institution 1952: 188, as  Plumularia margaretta).— USA: Florida, FloridaCurrent off Miami ( Adams 1960: 81, as  Monotheca margaritta(sic)).— Aruba: North of Punta Braboe (=Punta Brabo), on  Thalassia( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— Bonaire: Oranjepan (=Oranje Pan), on stranded  Sargassum( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— Venezuela: Islote Aves, northern lagoon, on algae, near low water ( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— Barbuda: Martello Tower Beach, on algae ( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— St. Kitts & Nevis: St. Kitts, Frigate Bay, on algae, tidal zone ( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— Sint Maarten: Great Bay, on algae, ca. 2 m( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— Virgin Islandsof the United States: St. John, Turner Bay, on  Turbinaria, tidal zone ( Van Gemerden-Hoogeveen 1965: 69, as  Plumularia margaretta).— USA: Texas, West Flower Garden Bank, on floating  Sargassum( Defenbaugh 1974: 102, as  Plumularia margaretta).—Gulf Stream, several stations between Floridaand New Jersey, on  Sargassum polyceratium,  S. pteropleuron, Sargassumsp., and  S. ramifolium( Rackley 1974: 45, as  Plumularia margaretta).— Colombia: Santa Marta area ( Wedler 1975: 340, as  Monotheca margareta; Bandel & Wedler 1987: 42, as  Monotheca( Plumularia) margaretta).— Belize: Carrie Bow Cay ( Spracklin 1982: 246, as  Plumularia margaretta).— Colombia: Bahía de Cartagena ( Flórez González 1983: 121, as  Plumularia margaretta).— USA: South Carolina, middle continental shelf ( Wenner et al. 1984: 21, 40, as  Plumularia margaretta).— USA: Georgia, inner continental shelf ( Wenner et al. 1984: 40, as  Plumularia margaretta).— Belize: Twin Cays ( Calder 1991b: 223).— Belize: South Water Cut, South Water Cay, on  Thalassia( Kaehler & Hughes 1992: 331).— Colombia: Bahía de Chengue, on  Rhizophora( Reyes & Campos 1992: 108, as  Plumularia margaretta).— Bermuda: on pelagic  Sargassum fluitansand  S. natans( Calder 1995: 540).— Bermuda: Natural Arches Beach, on stranded  Sargassum fluitans+ Castle Harbour, Wof Castle Roads, on  Thalassia, 2–3 m+ Whalebone Bay, on stranded  Sargassum fluitans+ St.Catherine’s Beach, on stranded  Sargassum fluitans+ Atlantic Ocean, 2 kmoff Castle Roads, on rubble, 73 m+ Burchall’s Cove, on stranded  Sargassum fluitans+ Atlantic Ocean, 2 kmoff Natural Arches Beach, on rhodolith, 70 m(Calder 1997: 11).— Bermuda: Argus (=Plantagenet) Bank + Challenger Bank ( Calder 2000: 1133).— Cuba: Ciudad de La Habana province, Playa Mégano, 0.5 m( Ortiz 2001a: 64).— Panama: Bocas del Toroarea, Boca del Drago, 09°25’36.3”N, 82°19’30.1”W, 1-3 m+ Bocas del Toroarea, Cayos Zapotilla, 09°15.564’N, 82°02.750’W, 7-8 m+ Bocas del Toroarea, Swan’s Key, 09°27’12.2”N, 82°18’01.8”W, 1-4 m+ Bocas del Toroarea, Bastimentos (front), 09°20.898’N, 82°09.959’W, 1-4 m+ Bocas del Toroarea, Bastimentos (north), 09°20.898’N, 82°09.959’W, 1-4 m( Calder & Kirkendale 2005: 482).—French Lesser Antilles: Guadeloupe, Grande-Terre, Les Arches, 16°27.529’N, 61°32.021’W, 17 m+ Grande-Terre, Pointe d’Antigues, 16°26.251’N, 61°32.523’W, 10–15 m, on an alga + Grande-Terre, harbor of Port-Louis, 16°24.720’N, 61°31.910’W, on red algae ( Galea 2010: 29, as  Plumularia margaretta).— Cuba: Golfo de Batabanó, Cayo Real, Cayería San Felipe ( Castellanos-Iglesias et al. 2011: 25).—French Lesser Antilles: Martinique( Galea 2013: 50, as  Plumularia margaretta).—Caribbean Sea ( Wedler 2017b: 163, figs. 206A, B, 207A, B, 208).— Mexico: Alacranes Reef, on algae, soft coral ( Mendoza-Becerril et al. 2018b: 131).— Panama: Bocas del Toroarea, near Bocatorito Bay ( Miglietta et al. 2018b: 108, as  Plumularia margaretta). 2430643697 [151,1062,1077,1105] Bahamas Little 107 108 1 Cat Island holotype 2430643557 2018-04-03 ROMIZ D. Calder 26.449165 Sanibel Island 20 -82.01833 Lighthouse Point 107 108 B4398 1