Bougainvillia Lesson, 1830

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141 : 17-18

Genus Bougainvillia Lesson, 1830

Bougainvillia Lesson, 1830: 118 .

Type species. Bougainvillia macloviana Lesson, 1830 , by monotypy.

Remarks. The genus Bougainvillia Lesson, 1830 , with life cycles including both hydroid and medusa stages, is well-represented in the western North Atlantic. The guidebook on hydroids of the Atlantic coast of North America by Fraser (1944) includes five species under the genus, namely B. superciliaris L. Agassiz, 1849 , B. carolinensis ( McCrady, 1859) , B. rugosa Clarke, 1882 , B. longicirra Stechow, 1914 , and B. inaequalis Fraser, 1944 . In studies on medusae, Kramp (1959, 1961) reported nine species of Bougainvillia from the same region, including B. britannica ( Forbes, 1841) , B. ramosa ( Van Beneden, 1844b) (= B. muscus Allman, 1863 ), B. superciliaris L. Agassiz, 1849 , B. principis (Steenstrup, in Lütken, 1850) , B. carolinensis ( McCrady, 1859) , B. platygaster ( Haeckel, 1879) , B. rugosa Clarke, 1882 , B. niobe Mayer, 1894 , and B. frondosa Mayer, 1900b . Bougainvillia aberrans Calder, 1993a , a deepwater species differing from the others in having a reduced medusa stage, is added here to these lists.

Significant knowledge gaps exist about the hydroid and medusa stages of several species assigned to Bougainvillia in the western North Atlantic. Both B. longicirra and B. inaequalis are poorly known and based to date solely on their hydroid stages.The validity of the former has been questioned by Fraser (1944), and that of the latter by Deevey (1950). The taxonomic status of each one needs to be explored, although the validity of B. inaequalis was upheld by Calder & Choong (2018). The medusa B. frondosa seems well-founded taxonomically, but its hydroid stage is unknown ( Vannucci & Rees 1961). Meanwhile, attempts at linking the two stages of a given species have sometimes resulted in error or uncertainty. In the original account of B. superciliaris by L. Agassiz (1849), only the medusa stage was described. Later, a hydroid forming a rather large (ca. 5 cm high), erect, irregularly branched, monosiphonic colony was taken to be its polypoid stage (L. Agassiz 1862). That concept of the species, adopted in subsequent publications on hydroids of eastern North America (see synonymy list in Fraser 1944), is amost certainly mistaken, as discussed elsewhere ( Vannucci & Rees 1961; Schuchert 2007; Calder 2017). Life cycle studies by Werner (1961) and others indicate that the hydroid of B. superciliaris is stolonal. The identity of the erect and branched colony described by Agassiz is thus uncertain. In the case of B. carolinensis, McCrady (1859) provided a satisfactory account of the medusa, but the hydroid somewhat tenuously linked to it by him was described simply as having about 12 tentacles and measuring “…about an inch (2.5 cm) or slightly more in height.” That description has been insufficient to distinguish the species. Detailed descriptions of a hydroid thought to be B. carolinensis by Mayer (1910a), Fraser (1944), and others, following an account by A. Agassiz (1865, as Margelis carolinensis ),may well have been based on a different species. The very large hydroid (up to 30 cm high) described by Agassiz was found growing in abundance on Fucus vesiculosus , a boreal algal species that does not occur in warm-temperate Charleston Harbor, South Carolina, where McCrady’s medusa was found. The identity of McCrady’s hydroid thus remains uncertain, as does the one of A. Agassiz. The life cycle of B. carolinensis has yet to be carefully followed in the laboratory, and genetic studies on hydroids and medusae of the species are lacking.

Of the species listed above, reliable characterizations of both hydroid and medusa stages have been described for B. rugosa (Clarke 1881; Calder 1971), B. muscus ( Russell 1953, as B. ramosa ; Calder 1988, 2010; Schuchert 2007), and B. aberrans ( Calder 1993a) , all of which have erect colonies. Complete life cycles are also known for Bougainvillia britannica , with mostly stolonal colonies having unusually long pedicels ( Edwards 1964, 1966), and B. principis , with stolonal colonies ( Edwards 1966). Hydroids of those two species have yet to be identified from the east coast of North America. As for B. platygaster , polyp and medusa buds arise from the manubrium of the medusa ( Kramp 1957, 1959; Schuchert 2007). No polypoid stage is known in B. niobe ( Vannucci & Rees 1961) , another species in which medusa buds are produced on the manubrium.

Given the unsatisfactory state of knowledge of hydroids of Bougainvillia in the western North Atlantic, a description is provided below of a species assigned here to B. rugosa . Meanwhile, genetic evidence does not support monophyly of Bougainvillia , nor of the family Bougainvilliidae as currently constituted ( Mendoza-Becerril et al. 2018a).