Bougainvillia rugosa Clarke, 1882

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141 : 18-21

Bougainvillia rugosa Clarke, 1882

Figs. 2 b–d, 3

Bougainvillia rugosa Clarke, 1882: 135 .

Bougainvillea rugosa Clarke, 1882: 140 , pl. 8, figs. 21–24 [incorrect subsequent spelling of Bougainvillia ].

Type locality. USA: Virginia, Hampton Roads and lower Chesapeake Bay ( Clarke 1882: 141) .

Material examined. Fort Myers Beach, on stranded Idiellana pristis , 01 March 2013, one colony, 9 mm high, with gonophores, coll. D. Calder, ROMIZ B4332.— Sanibel Island , beach at Lighthouse Point, on stem of Eudendrium carneum stranded on shore, 13 December 2017, one colony, 6 mm high, with medusa buds, medusae liberated and cultured five days, coll. D. Calder, ROMIZ B4333 .— Sanibel Island , beach at Lighthouse Point, on stem of Eudendrium carneum stranded on shore, 13 December 2017, one colony, 1.1 mm high, with medusa buds, coll. D. Calder, ROMIZ B4334 [preserved in 70% ethanol (never in formalin)].— Sanibel Island , beach at Lighthouse Point, detached and stranded on shore, 29 January 2018, one colony, 6 cm high, with medusa buds, medusae liberated, coll. D. Calder, ROMIZ B4335 .— Fort Myers Beach , Salty Sam’s Marina, 26°27’21.7”N, 81°56’34.6”W, on floating dock, <0.1 m, 19° C, 05 February 2018, four colonies or colony fragments, up to 3.5 cm high, with gonophores, medusae liberated, coll. D. Calder, ROMIZ B4336 .

Description. Colonies with some stolonal hydranths but most with erect hydrocauli, up to 6 cm high, growth monopodial with terminal hydranths. Hydrocaulus slender, monosiphonic, not robust, often crooked and most slender at base, arising from a creeping hydrorhiza, giving rise to more-or-less alternate pedicels; pedicels unbranched or with an occasional secondary pedicel. Each pedicel slender basally, gradually increasing in diameter distally, supporting a terminal hydranth. Perisarc thin, irregularly smooth, without annulations everywhere, encrusted with particles of silt, extending over base of hydranth as a pseudohydrotheca, not investing bases of tentacles or hypostome. Pseudohydrothecae cup-shaped around retracted hydranths, sheath-like over extended ones, slightly striated horizontally. Hydranths fusiform when contracted, nearly cylindrical when extended, with a distal whorl of tentacles, hypostome prominent, typically dome-shaped. Tentacles filiform, highly contractile, about 11–13 in number on fully developed hydranths, amphicoronate in extended polyps, arranged in two very close whorls. Perisarc light-tan; hydranths white, with endoderm faintly ochre-coloured.

Gonophores free medusae. Medusa buds pyriform to bulbous, arising singly on relatively short stalks, most arising from hydranth pedicels but a few from hydrocaulus, invested in perisarc prior to release; developing gonads apparent in advanced buds. Newly liberated medusae dome-shaped, umbrella about 0.55 mm high and wide; mesoglea fairly thick, umbilical canal present in some but absent in most, with vestige of attachment to hydroid sometimes forming an apical cone; gastric peduncle lacking; manubrium tubular, quite short, extending less than half-way to velar opening; mouth simple; oral tentacles four, unbranched, inserted just above mouth, appearing slightly capitate in having a distal cluster of nematocysts; radial canals four; ring canal present; tentacle bulbs four, conical, with rounded bases; marginal tentacles filiform, highly contractile, nearly always 12 in number, with three per tentacle bulb, ocelli eight, conspicuous, dark red, with one at base of each of first two tentacles in each bulb, in clockwise order around oral end of medusa; tentacles having ocelli somewhat more developed than those lacking that structure; velum broad. Gonads developed, or obviously developing, in newly liberated medusae. Endoderm brownish orange, colour intensity varying from one specimen to another but typically quite faint, gonad sometimes appearing slightly green. Medusae active swimmers. Three-day-old medusae larger (ca. 0.8–1 mm in diameter), with much thicker mesoglea and with more advanced gonadal development, but otherwise little changed, having a short manubrium, four unbranched oral tentacles, no gastric peduncle, and four marginal tentacle bulbs, each with three marginal tentacles and usually with two ocelli, less frequently with three. After five days, with little morphological change but with signs of declining vigour, all remaining medusae were preserved.

Remarks. Bougainvillia rugosa Clarke, 1882 is an infrequently reported and insufficiently known species, and its validity has even been questioned ( Kramp 1959). For those reasons, both polypoid and medusoid stages have been described here. The hydroid of B. rugosa , which can attain a significant size, has been reported more often than its small and relatively short-lived medusa. Much smaller, monosiphonic colonies assigned here to B. rugosa (ROMIZ B4333) were at first thought to be a different species. However, a continuum appears to exist from these tiny colonies to those that are large and polysiphonic (ROMIZ B4335, ROMIZ B4336), as is considered typical of B. rugosa .

In support of the identification made here, medusae liberated from hydroids collected during December 2017 (ROMIZ B4333) were cultured at ambient temperatures (ca. 19–23° C) and in polyhaline salinities for five days. Specimens were fed fragments of yolk from hardboiled eggs twice each day. Other than an increase in size, a thickening of the mesoglea, and increasing development of the gonads (all males), no significant morphological changes were observed. Marginal tentacle numbers remained at 12, oral tentacles did not become branched, and ocelli were eight in number ( Figs. 2c, d ). In this, the development corresponded with that of B. rugosa , as described earlier ( Clarke 1882; Calder 1971).

While fully developed hydroids of B. rugosa are large (up to 25 cm high), robust, and polysiphonic, some of those examined here (ROMIZ B4333) were small (ca. 6 mm high), slender, and monosiphonic, as noted above. Larger (6 cm high), more robust, and strongly polysiphonic specimens (ROMIZ B4335, ROMIZ B4336), like those described from Chesapeake Bay ( Clarke 1882; Calder 1971), were also collected. Most of the medusae liberated from those colonies had the usual 12 marginal tentacles and eight ocelli, but a few had 1–2 additional but miniscule ocelli, with one at the base of the somewhat less-developed third tentacle on each marginal bulb. Cnidomes of the two morphotypes ( Fig. 3 ) comprised desmonemes (3.2 – 3.8 long x 1.9 – 2.3 μm wide, undischarged, n=10, ROMIZ B4333; 3.8 – 4.2 long x 2.3 – 2.7 μm wide, undischarged, n=10, ROMIZ B4335) and heterotrichous microbasic eu- ryteles (5.1 – 5.7 long x 2.2 – 2.9 μm wide, undischarged, n=10, ROMIZ B4333; 5.2 – 5.8 long x 2.3 – 2.8 μm wide, undischarged, n=10, ROMIZ B4335).

In colony size and form, small hydroids of B. rugosa somewhat resemble those of B. muscus . However, their newly liberated medusae had 12 marginal tentacles (three per tentacle bulb) instead of eight (two per tentacle bulb) as in B. muscus , and their gonads were partially developed. Indeed, gonads were apparent even on medusa buds still attached to the hydroid. With growth, medusae of the two species become much more alike, at least initially, typically having 12 marginal tentacles, eight ocelli, and unbranched (or minimally branched) oral tentacles. Those of the two species appear to be relatively short-lived, and their eggs are armed with an outer envelope bearing numerous heterotrichous microbasic euryteles. Another species having a medusa with 12 marginal tentacles at liberation is the boreal B. principis (Steenstrup, in Lütken, 1850) . However, it has 12 ocelli instead of eight, its gonads are undeveloped, its oral tentacles are branched, its exumbrella bears numerous nematocysts, and its hydroid is stolonal ( Schuchert 2007). Newly liberated medusae of B. macloviana Lesson, 1830 have 2–5 marginal tentacles and 2–3 ocelli per tentacle bulb, and branched or slightly branched oral tentacles. Unlike B. rugosa , its hydroid is stolonal and the species is autochthonous to high latitudes ( Schuchert 2007).

The hydroid of B. rugosa is eurytopic, having been found at salinities between 18‰–34‰ ( Calder 1976) and at water temperatures between 6–32° C (Calder 1990). Colonies with medusa buds were collected during autumn and winter in southwest Florida during this study. The species was found on a variety of substrates in tributaries of southern Chesapeake Bay ( Calder 1971), including submerged ropes, wooden pier pilings and fouling panel frames, test panels of acrylic plastic and asbestos fibre, sponges ( Lissodendoryx isodictyalis ), bryozoans ( Alcyonidium verrilli ), tubicolous polychaetes ( Hydroides hexagona ), shells of oysters ( Crassostrea virginica ), a crab carapace ( Libinia sp.), and ascidians ( Molgula manhattensis ).

Bougainvillia rugosa has been reported from Chesapeake Bay ( Clarke 1882; Calder 1971) to the Gulf of Mexico ( Calder & Cairns 2009), and with question to the Caribbean Sea ( Stechow 1919). It has also been reported from Brazil ( Migotto 1996). Stechow’s record of the species, from the U.S. Virgin Islands, is somewhat uncertain in having been based on sterile material. Also of uncertain identity is a medusa identified as B. rugosa by Mayer (1910a) from Charleston Harbor, South Carolina. Unlike B. rugosa , 12 ocelli instead of eight were present adjacent to the 12 marginal tentacles in his specimen.

Based on current knowledge, B. rugosa is an inhabitant of shallow inshore waters in warm-temperate regions of the western Atlantic, and especially the southeastern United States. The morphologically similar B. inaequalis Fraser, 1944 occurs under similar ecological conditions. Clarification of relationships between the two is warranted, although hydroids of B. inaequalis appear to have perisarc on stems and branches that is much more deeply wrinkled than in B. rugosa . That species has been thought to intergrade with B. carolinensis McCrady, 1859 as well ( Deevey 1950).

Reported distribution. Gulf coast of Florida. First record.

Elsewhere in western North Atlantic. USA: Virginia, Hampton Roads and areas in lower Chesapeake Bay, “Laminarian zone”, on Alcyonidium ( Clarke 1882: 141, as Bougainvillea rugosa ).—? USA: South Carolina, Charleston Harbor, medusa ( Mayer 1910a: 171, pl. 17, fig. 2).— USA: North Carolina, Bogue Sound, 10 or 12 feet (3 or 4 m) + Marshallberg, near low water ( Fraser 1912b: 347).—? Virgin Islands of the United States: St. Thomas, Charlotte Amalie, surface ( Stechow 1919: 27).— USA: Louisiana, Bayou Mussel + Pass Sortie ( Fraser 1944: 53).— USA: Vir- ginia, Norfolk, Norfolk Naval Base Pier 12, on fouling panels, 5 m ( Calder & Brehmer 1967: 153).— USA: North Carolina, Beaufort (medusa) ( Allwein 1967: 122).— USA: Virginia, York River (Ellen Island; Gloucester Point) + James River (Hampton Bar; Norfolk Naval Base Pier 12; Hampton Roads Middle Ground) ( Calder 1971: 36).— USA: Virginia, entrances of the Rappahannock, York, and James river estuaries ( Andrews 1973: 231).— USA: South Carolina, coastal zone, many areas ( Calder 1976; 1990; Calder & Hester 1978: 89).— USA: South Carolina, Folly River area, Oak Island, oyster reef + Folly river area, pilings + Isle of Palms, marina, floating docks + Beaufort River, channel + Hunting Island, seawall and rubble + Beaufort River area, floating docks ( Fox & Ruppert 1985: 152, 160, 177, 204, 226, 232).— USA: South Carolina, Beaufort, floating dock, 32°26’16”N, 80°40’29”W ( Caine 1987: 84; 1989: 425; 1998: 317).— USA: Georgia: St. Catherines Island, docks ( Prezant et al. 2002: 22).— USA: Georgia, Sea Islands, on loggerhead turtles ( Frick et al. 2002: 954).—Caribbean Sea ( Wedler 2017b: 22, figs. 6A–C, in caption as Bougainvillia ramosa ).

Figures

FIGURE 2. a, Bimeria humilis: colony with two hydranths, Fort Myers Beach, ROMIZ B4330. Scale equals 0.2 mm. b, Bougainvillia rugosa: part of colony with hydranth and medusa bud, Sanibel Island, ROMIZ B4333. Scale equals 0.2 mm. c, Bougainvillia rugosa: newly liberated medusa from same hydroid, ROMIZ B4333. Scale equals 0.1 mm. d, Bougainvillia rugosa: 3-day-old laboratory-raised medusa from same hydroid, ROMIZ B4333. Scale equals 0.1 mm. e, Calyptospadix cerulea: part of hydrocaulus with branches, pedicels, hydranths, and a female gonophore, Caloosahatchee River at Fort Myers, ROMIZ B4340. Scale equals 0.3 mm. f, Amphinema sp.: hydranth and pedicel, Captiva Island, ROMIZ B4338. Scale equals 0.2 mm. g, Amphinema sp.: hydranth and pedicel, Captiva Island, ROMIZ B4338. h, Eudendrium carneum: hydranth and pedicel, Sanibel Island, ROMIZ B4343. Scale equals 0.2 mm. i, Eudendrium carneum: part of female colony with encapsulated embryos, Sanibel Island, ROMIZ B4344. Scale equals 0.4 mm.

FIGURE 3. Bougainvillia rugosa: nematocysts of hydroid stage. a, desmoneme, ROMIZ B4333. b, heterotrichous microbasic eurytele, ROMIZ B4333. c, desmoneme, ROMIZ B4335. d, heterotrichous microbasic eurytele, ROMIZ B4335.