Lytocarpia flexuosa ( Lamouroux, 1816 )

Calder, Dale R. & Faucci, Anuschka, 2021, Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands, Zootaxa 5085 (1), pp. 1-73 : 49-51

Lytocarpia flexuosa ( Lamouroux, 1816)

Fig. 14e

Aglaophenia flexuosa Lamouroux, 1816: 167 .

Type Locality. “Indes Orientales” ( Lamouroux 1816).

Voucher material. Pearl & Hermes Atoll , unattached, 19.ix.2002, two colonies, to 4.4 cm high, without corbulae, coll. A. Faucci, ROMIZ B5479 .

Remarks. Most records of Lytocarpia flexuosa ( Lamouroux, 1816) to date have been from locations in the western Indian Ocean (e.g., Billard 1907, as Thecocarpus giardi ; Millard 1975, as T. flexuosus flexuosus ; GravierBonnet 1979, as T. flexuosus ; Rees & Vervoort 1987; Gravier-Bonnet & Bourmaud 2006). Rees & Vervoort (1987) considered reports of the species from the East Indies by Lamouroux (1916, as Aglaophenia flexuosa ) and from Australia by Kirchenpauer (1872, as A. flexuosa ) to be dubious inasmuch as it has not been recorded again from the Tropical Western Pacific. Its discovery far to the east at Pearl & Hermes Atoll in this study may reduce some of the doubt. The reported range of the species now extends from South Africa ( Millard 1975) and the Red Sea ( Mergner & Wedler 1977) to the Northwestern Hawaiian Islands.

Considerable variation in colony form and hydrothecal morphology has been described in hydroids assigned to L. flexuosa ( Millard 1958, as T. giardi, 1962 , as T. flexuosus, 1975 , as T. flexuosus ). In particular, branching of the colony may be in the form of a spiral or an umbel. Hinge joints vary in location, and hydrocladia may be short or long. The abcauline marginal cusp may be solid or hollow, and it may be simple or bifurcated. One pair or more of the lateral cusps are usually bifid, but not always. The existence of intermediate forms led Millard (1962, 1975) to regard the variants as subspecies of L. flexuosa .

Rees & Vervoort (1987: 175) provided a synonymy list for L. flexuosa . Included in it was Thecocarpus giardi Billard, 1907 and, with question, Aglaophenia bifida Stechow, 1923b . They suspected that none of the various subspecies of L. flexuosa recognized by Millard (1962, 1975), including T. flexuosus plumiferus ( Kirchenpauer, 1872) , T. flexuosus solidus ( Millard, 1958) , and T. flexuosus umbellatus Millard 1962 , would prove to be valid. Their material most closely resembled that of the nominotypical subspecies, T. flexuosus flexuosus ( Lamouroux, 1816) . So, too, do specimens examined here from Pearl & Hermes Atoll.

As for T. flexuosus plumiferus, Kirchenpauer (1872) spelled its original species-group name two ways, as Aglaophenia plumifera in the text and as A. plumulifera in the figure captions. Under the Principle of the First Reviser (ICZN 1999, Art. 24.2) in nomenclature, Bedot (1912: 252) cited the two names together and selected A. plumifera as the correct original spelling.

In a study of hydroids on reefs at Juan de Nova Island, Gravier-Bonnet & Bourmaud (2006) found L. flexuosa only on the outer slope at 30 m. While the substrate of that biotope comprised a large amount of dead stony corals, it supported a diverse hydroid fauna of some 58 species. Specimens collected there occurred on hard substrates, algae, and sessile benthic invertebrates. Aglaopheniids, with 16 species, were well-represented, as were solanderiids .

Hydroids of L. flexuosa were described by Lamouroux (1816) as having a shiny fawn colour (“couleur fauve brillant”).

Reported Distribution. Hawaiian archipelago. First record.

Elsewhere. “East Indies” ( Lamouroux 1816, as Aglaophenia flexuosa ); Australia ( Kirchenpauer, 1872, as A. flexuosa ); Madagascar ( Billard 1907, as Thecocarpus giardi ; Gravier-Bonnet 1979, as T. flexuosus ); South Africa ( Millard 1975, as T. flexuosus flexuosus ), including Agulhas Bank ( Stechow 1923b, as Aglaophenia (?) bifida ; Millard 1975, as T. flexuosus solidus ); Mozambique ( Millard 1975, as T. flexuosus flexuosus ); Red Sea ( Mergner & Wedler 1977, as T. flexuosus var. flexuosus ); Gulf of Aden ( Rees & Vervoort 1987); Oman ( Rees & Vervoort 1987); Juan de Nova Island ( Gravier-Bonnet & Bourmaud 2006).

Figures

FIGURE 14. Aglaopheniidae. a, Aglaophenia postdentata Billard, 1913, part of a cladium with two hydrothecae, Gardner Pinnacles, ROMIZ B5462. Scale equals 0.1 mm. b, Aglaophenia suensonii Jäderholm, 1896, part of a cladium with three hydrothecae, Laysan Island, ROMIZ B5463. Scale equals 0.1 mm. c, Aglaophenia suensonii Jäderholm, 1896, corbula, Laysan Island, ROMIZ B5463. Scale equals 0.2 mm. d, Aglaophenia whiteleggei Bale, 1888, part of a cladium with two hydrothecae, Pearl & HermesAtoll, ROMIZ B5464. Scale equals 0.1 mm. e, Lytocarpia flexuosa (Lamouroux, 1816), part of a cladium with three hydrothecae, Pearl & Hermes Atoll, ROMIZ B5479. Scale equals 0.1 mm. f, Lytocarpia phyteuma (Stechow, 1919b), part of a cladium with two hydrothecae, Pearl & Hermes Atoll, ROMIZ B5468. Scale equals 0.1 mm. g, Macrorhynchia philippina Kirchenpauer, 1872, part of a cladium with two hydrothecae, Midway Atoll, ROMIZ B5470. Scale equals 0.1 mm. h, Macrorhynchia phoenicea (Busk, 1852), part of a cladium with three hydrothecae, Gardner Pinnacles, ROMIZ B5475. Scale equals 0.1 mm. i, Macrorhynchia phoenicea (Busk, 1852), one phylactocarp, without gonothecae, Gardner Pinnacles, ROMIZ B5475. Scale equals 0.2 mm.