Halopteris alternata ( Nutting, 1900 )

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141 : 100-101

Halopteris alternata ( Nutting, 1900)

Figs. 23 a–c

Plumularia alternata Nutting, 1900: 62 , pl. 4, figs. 1, 2.— Wallace, 1909: 136.— Fraser, 1943: 96.

Plumularia diaphana .— Fraser, 1944: 343.—(?) Joyce, 1961: 72, pl. 18, fig. 3.—(?) Shier, 1965: 59, pl. 32 [not Plumularia diaphana ( Heller, 1868) ].

Halopteris diaphana diaphana .— Vervoort, 1968: 58, figs. 27a, b.

Halopteris alternata .— Schuchert, 1997: 42.

Type locality. Bahamas: Barracuda Rocks ( Nutting 1900: 62, as Plumularia alternata ) .

Material examined. Fort Myers Beach, stranded intertidally on detached Idiellana pristis , 16 February 2013, three colony fragments, up to 8 mm high, without gonophores, coll. D. Calder, ROMIZ B4400.

Remarks. The nomenclature of the hydroid now known once again as Halopteris alternata ( Nutting, 1900) was resolved by Schuchert (1997). For a time during the mid- and late 20 th century, this hydroid was thought to be conspecific with the mostly European H. diaphana ( Heller, 1868) . As noted by Schuchert, and reiterated elsewhere ( Calder 2013), morphological differences distinguishing H. alternata from its congener include (1) the usual presence of an axillar nematotheca beneath hydrothecae on the hydrocaulus, (2) hydrocladia with homomerous rather than heteromerous segmentation, (3) athecate hydrocladial internodes with one rather than two or three nematothecae, (4) female gonothecae that are fusiform and essentially straight rather than cornucopia-shaped. Taxonomic confusion over the two species, both of which occur in the tropical western Atlantic, makes it difficult to untangle their distribution records. Of the two, however, H. alternata is by far the more frequently encountered species.

Halopteris alternata is widespread in shallow waters throughout the tropical western North Atlantic. It extends from the Caribbean coast of South America ( Vervoort 1968, as Halopteris diaphana diaphana ) northwards to shelf waters of South Carolina ( Wenner et al. 1984, as H. diaphana ) and seawards to Bermuda (Calder 1997, as H. diaphana ). A population on pelagic Sargassum believed to be the same species is carried northwards by the Gulf Stream ( Fraser 1912b, as Plumularia alternata ) and into the central North Atlantic Ocean by the North Atlantic Drift ( Timmermann 1932, as Plumularia catharina ).

Approaching the northern geographic range of H. alternata is the southern limit of Halopteris tenella ( Verrill, 1874d) , a species of the temperate zone in eastern North America. It is the most abundant plumularioid found in inshore waters, including estuaries, from southern New England ( Nutting 1901; Petersen 1964; both as Schizotricha tenella ) to South Carolina ( Calder & Hester 1978; Calder 1983; both as S. tenella ). While the two species are somewhat similar in morphology and could easily be confused, H. tenella differs from H. alternata in having (1) heteromerously rather than homomerously segmented hydrocauli, (2) hydrocladia that are branched rather than unbranched, and with two kinds of athecate hydrocladial internodes, long nematothecate ones and very short anematothecate ones, (3) female gonothecae that are cornucopia-shaped instead of fusiform or nearly so. Colonies of H. tenella also attain a much larger size, reaching 10 cm high ( Calder 1971). Fraser (1944) believed that this species extended to the Caribbean region, having included Leloup’s (1935a) reports of Antennella diaphana from Bonaire and Aruba in the synonymy of H. tenella . That synonymy is not upheld here, and the southern limit of H. tenella is taken to be the southeastern United States ( Calder 1983). It is known to occur as far north as the Damariscotta River estuary, Maine (personal unpublished observations). The only record of the species from the Gulf of Mexico to date is a questionable one from Louisiana by Fraser (1944, as Schizotricha tenella ). Also of uncertain identity is the species identified as Plumularia diaphana from Seahorse Key, on the Gulf coast of Florida, by Joyce (1961). His illustration of the trophosome, and especially the hydrocladia (pl. 18, fig. 3) appears as much like H. tenella or H. diaphana as H. alternata . Likewise uncertain is the identity of material included in P. diaphana by Shier (1965) from the Cape San Blas area of Florida. Hydrocauli were described as being heteromerously segmented, as in H. tenella and H. diaphana . The hydroids of both Joyce and Shier were unfortunately sterile.

One of the three colony fragments in material of H. alternata examined here (ROMIZ B4400) constituted an “ Antennella form” ( Fig. 23c ), although a developing apophysis and hydrocladium was present.

Schuchert (1997) provided a fuller account of H. alternata , and compared it with related species.

Reported distribution. Gulf coast of Florida. Dry Tortugas ( Wallace 1909: 136, as Plumularia alternata ; Fraser 1943: 96, as Plumularia alternata ; Fraser 1944: 343, as Plumularia diaphana ; Schuchert 1997: 43).—?Seahorse Key ( Joyce 1961: 72, as Plumularia diaphana ).—?Cape San Blas area ( Shier 1965: 59, as Plumularia diaphana ).— Dry Tortugas, Loggerhead Key, tidal zone ( Vervoort 1968: 59, as Halopteris diaphana diaphana ).

Elsewhere in western North Atlantic. Bahamas: Barracuda Rocks ( Nutting 1900: 62, as Plumularia alternata ).— Bermuda: on floating Sargassum ( Congdon 1907: 484, as Plumularia alternata ).— USA: Louisiana, Gulf of Mexico off Marsh Island, 27°10’N, 91°50’W ( Stechow 1912: 363, as Plumularia alternata ).— Cuba: W of Havana, 23°14’N, 84°08’W ( Stechow 1912: 363, as Plumularia alternata ).— USA: North Carolina, Beaufort area, on floating Sargassum and Turbinaria (Fraser 1912: 381, as Plumularia alternata ).—Sargasso Sea: east of New Jersey, on floating seaweed ( Broch 1913: 4, as Plumularia catharina ).— Bermuda: on floating Sargassum ( Bennitt 1922: 255, as Plumularia diaphana ).—Sargasso Sea, on Sargassum , 34°25’N, 40°05’W + 31°56’N, 48°25’W + 30°20’N, 53°10’W + 27°20’N, 61°10’W ( Timmermann 1932: 298, 301, as Plumularia catharina ).— Dominican Republic: off Monte Cristi, on Sargassum ( Timmermann 1932: 299, as Plumularia catharina ).—North Atlantic Drift: 41°00’N, 34°00’W, on Sargassum ( Timmermann 1932: 301, as Plumularia catharina ).— Aruba: Boekoeti Reef, 0.2 m ( Leloup 1935a: 52, as Antenella diaphana forme typica).—Sargasso Sea: 29°N, 44°W, on Sargassum ( Leloup 1935a: 52, as Antenella diaphana forme typica).—Atlantic Ocean: Gulf Stream, on pelagic Sargassum + Sargasso Sea, on pelagic Sargassum (Burkenroad, in Parr 1939: 24, as Plumularia catharina ).— Trinidad & Tobago: Trinidad, Maguaripe Bay (=Macqueripe Bay) ( Fraser 1943: 96, as Plumularia alternata ).— USA: Louisiana, Grand Isle, on floating Sargassum ( Fraser 1944: 343, as Plumularia diaphana ).— Aruba: 8 miles (13 km) SW of San Nicolaas Bay ( Fraser 1947b: 13, as Plumularia diaphana ).— Trinidad & Tobago: Tobago, Buccoo Bay, shore ( Fraser 1947b: 13, as Plumularia diaphana ).— USA: Florida, Biscayne Bay ( Weiss 1948: 158, as Plumularia diaphana ).— USA: Louisiana, Grand Isle, on Sargassum ( Behre 1950: 7, as Plumularia alternata ).—Unstated location: on buoys ( Woods Hole Oceanographic Institution 1952: 188, as Plumularia diaphana ).— USA: Mississippi, Mississippi Sound, on Sargassum ( Fincher 1955: 92, as Plumularia diaphana ).— Aruba: Boekoeti, northern sea side, on coral fragments, tidal zone ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana ).— Bonaire: Klein Bonaire, east coast landing, on Sargassum , sponge, and stone, tidal zone ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana ).— Bonaire: Palu Lechi, on sponge, low tide ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana ).— St. Kitts & Nevis: St. Kitts, Frigate Bay, tidal zone ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana ).— Sint Maarten: Simpson Lagoon, W shore of Little Key, on algae, tidal zone ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana ).— Virgin Islands of the United States: St. John, Turner Bay, on Turbinaria , tidal zone ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana ).— Jamaica: Kingston, on Halocordyle disticha (= Pennaria disticha ) ( Vervoort 1968, as Halopteris diaphana diaphana ).— Colombia: Puerto Colombia, jetty ( Vervoort 1968, as Halopteris diaphana diaphana ).— USA: Texas, West Flower Garden Bank, on floating Sargassum ( Defenbaugh 1974: 102, as Plumularia diaphana ).—Gulf Stream, several stations between Florida and New Jersey, on Sargassum natans I, S. polyceratium , S. pteropleuron , S. bermudense ( Rackley 1974: 43, as Halopteris diaphana ).— Colombia: Santa Marta area ( Wedler 1975: 340, as Halopteris diaphana ; Bandel & Wedler 1987: 38, as Halopteris diaphana ).— Jamaica: south coast ( Mergner 1977: 122, as Halopteris diaphana ; 1987: 187, as Halopteris diaphana ).— Belize: Carrie Bow Cay ( Spracklin 1982: 246, as Halopteris diaphana ).— Colombia: Bahía de Cartagena ( Flórez González 1983: 123, as Halopteris diaphana diaphana ).— USA: South Carolina, middle continental shelf E of South Santee River, 32–36 m ( Wenner et al. 1984: 40, as Halopteris diaphana ).—? USA: Texas, banks on the continental shelf ( Rezak et al. 1985: 224, as Halopteris catharina ).— Bermuda: common inshore, and on pelagic Sargassum ( Calder 1986: 139, as Halopteris diaphana ).— USA: South Carolina and Georgia, inner continental shelf, on artificial reefs ( Wendt et al. 1989: 1119, as Halopteris diaphana ).— Belize: Twin Cays ( Calder 1991b: 223, as Halopteris diaphana ).— Colombia: Bahía de Chengue, on Rhizophora ( Reyes & Campos 1992: 108, as Halopteris diaphana ).— Bermuda: on pelagic Sargassum ( Calder 1995: 540, as Halopteris diaphana ).— Belize: Turin Cays (=Twin Cays) ( Schuchert 1997: 43).— Bonaire: Klein Bonaire ( Schuchert 1997: 43).— Jamaica: Kingston ( Schuchert 1997: 43).— Colombia: Puerto Colombia ( Schuchert 1997: 43).— Aruba: Boekoeti reef ( Schuchert 1997: 43).— Sint Maarten: Simpson Lagoon ( Schuchert 1997: 43).— St. Kitts & Nevis: St. Kitts, Frigate Bay ( Schuchert 1997: 43).— Virgin Islands of the United States: St. John ( Schuchert 1997: 43).— Bonaire: Poeloe Lechi ( Schuchert 1997: 43).— Bermuda: Whalebone Bay, on Thyroscyphus marginatus , Pennaria disticha , and pelagic Sargassum , 0–1.5 m + Castle Harbour, W of Castle Roads, on algae + Harrington Sound, Stream Passage Cave, on rock, 1 m + Atlantic Ocean, 2 km SE of Castle Roads, on coral rubble and algae, 70–73 m + Flatts Inlet, on pelagic Sargassum + Atlantic Ocean, 2.5 km SSE of Castle Roads, on rhodoliths, 60 m (Calder 1997: 36, as Halopteris diaphana ).— Bermuda: Challenger Bank + Argus (=Plantagenet) Bank ( Calder 2000: 1133).— Panama: Colón, Club Nautico, steel pilings, 09°21’51”N, 79°53’39”W, 0–1 m + Galeta, STRI Galeta Laboratory, dock, 09°24’08”N, 79°51’39”W, 0–2 m + Bocas del Toro area, Hospital Point, 09°20’00.7”N, 82°13’06.8”W, 0–2 m + Bocas del Toro area, Mangrove Inn, 09°19’52.6”N, 82°15’17.7”W, 2–3 m + Bocas del Toro area, Boca del Drago, 09°25’36.3”N, 82°19’30.1”W, 1–3 m + Bocas del Toro area, Cayos Zapotilla, 09°15.564’N, 82°02.750’W, 7–8 m + Bocas del Toro area, Crawl Cay, 09°15.261’N, 82°07.787’W, 2–4 m + Bocas del Toro area, near Laguna Bocatorito, 2–4 m + Bocas del Toro area, Swan’s Key, 09°27’12.2”N, 82°18’01.8”W, 1–4 m + Bocas del Toro area, Bastimentos, 09°20.898’N, 82°09.959’W, 1–4 m + Bocas del Toro area, “Emelio’s Beach”, 09°22.027’N, 82°14.336’W + Bocas del Toro area, Drago 2, mangrove, 1–2 m ( Calder & Kirkendale 2005: 483).—French Lesser Antilles: Guadeloupe, Basse-Terre, N of Malendure, 16°10’25.00”N, 61°46’58.00”W, rocky shore + Basse-Terre, Petite Anse, 16°05’47.00”N, 61°46’17.00”W, rocky shore + Basse-Terre, Anse à la Barque, 16°05’21”N, 61°46’00”W, rocky shore, dock, pilings ( Galea 2008: 41).—French Lesser Antilles: Les Saintes, Terre-de-Haut, Pompierre Bay, 15°52’25”N, 61°34’15”W, large rocks in seagrass meadows + Terre-de-Haut, Pain de Sucre, 15°51’45”N, 61°35’60”W, rocky shore ( Galea 2008: 41).—French Lesser Antilles: Guadeloupe, Grande- Terre, Pointe Plate, 16°27.220’N, 61°32.128’W + Grande-Terre, L’Oeil, 16°26.782’N, 61°32.405’W, 12–17 m + Grande-Terre, Passe à Colas, 16°21.269’N, 61°34.193’W, 10–15 m ( Galea 2010: 3, 4).—French Lesser Antilles: Les Saintes, Terre-de-Haut, Pointe Morel, 15°53.050’N, 61°34.410´W, 6–11 m + Terre-de-Haut, Pointe à Cabrit, 15°52.645’N, 61°36.125’W, 10–15 m ( Galea 2010: 5).— Cuba: Golfo de Batabanó, Cayo Campos (Castellanos- Iglesias et al. 2011: 16).— USA: Florida, off West Palm Beach, 13.7 m ( Calder 2013: 42).—French Lesser Antilles: Martinique ( Galea 2013: 50).—Caribbean Sea ( Wedler 2017b: 155, figs. 190A, B, 191–193).— Mexico: Alacranes Reef, on shipwreck ( Mendoza-Becerril et al. 2018b: 130, as Halopteris diaphana ).— Cuba: Havana, coral reef system west of the city (Castellanos et al. 2018: Supplementary Table S2).— Panama: Bocas del Toro area, Punta Caracol + Punta Hospital + near Bocatorito Bay ( Miglietta et al. 2018b: 108).

Figures

FIGURE 23. a, Halopteris alternata: part of a hydrocaulus with proximal end of a hydrocladium, Fort Myers Beach, ROMIZ B4400. Scale equals 0.1 mm. b, Halopteris alternata: part of a hydrocladium with two hydrothecae, Fort Myers Beach, ROMIZ B4400. Scale equals 0.1 mm. c, Halopteris alternata: part of hydrocaulus of an “Antennella form” with a developing hydrocladium, Fort Myers Beach, ROMIZ B4400. Scale equals 0.1 mm. d, Halopteris clarkei: part of hydrocaulus with proximal ends of two hydrocladia, Southwest Florida Shelf, ROMIZ B2097. Scale equals 0.1 mm. e, Halopteris clarkei: hydrocladial hydrotheca and nematothecae, Southwest Florida Shelf, ROMIZ B2097. Scale equals 0.1 mm. f, Halopteris clarkei: male gonotheca with a nematotheca, Southwest Florida Shelf, ROMIZ B2097. Scale equals 0.05 mm. g, Monostaechas quadridens: part of colony with a hydrotheca and nematothecae, Southwest Florida Shelf, ROMIZ B2100. Scale equals 0.1 mm. h, Ventromma halecioides: part of hydrocaulus with a hydrocladium, Sanibel Island, ROMIZ B4395. Scale equals 0.2 mm. i, Ventromma halecioides: part of hydrocaulus with proximal end of a hydrocladium, Sanibel Island, ROMIZ B4395. Scale equals 0.1 mm.