Solanderia secunda ( Inaba, 1892 )

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 59-61

Solanderia secunda ( Inaba, 1892)

Figs. 39, 40

Dendrocoryne secunda Inaba, 1892: 99 , figs. 111–113.

Ceratella fusca .— Nutting, 1905: 939 [not Ceratella fusca Gray, 1868 ].

Solanderia (?) minima . — Cooke, 1977: 73.

Solanderia minima .— Bouillon et al., 1992: 6.

Solanderia secunda (f. minima ).— Bouillon et al., 1992: pl. 14, fig. 5.

Solanderia secunda . — Cooke, 1977: 74.— Hoover, 1998: 22, fig.; 2006: 22, fig.

Type locality. Japan: Misaki ( Inaba 1892) .

Material examined. Maui: Albatross Stn. 4072, 56 fm (102 m), one fragmentary colony, 6.6 cm high, with hydranths, gonophores not seen, USNM 22271 .– Oahu: Waikiki, W end of natatorium, 8 ft (2 m), viii.1963, one colony (dry), 6.4 cm high × 9.4 cm wide, coll. G. Cooper, BPBM D356 .– Oahu: off Barber’s Point , 90–100 ft (27–30 m), 6.ii.1965, one colony (dry), 3.8 cm high × 7.9 cm wide, coll. D.P. Fellows, BPBM D405 .– Oahu : Kaneohe Bay , off Kipapa Island , 3–4 m, in cave, one colony, 13 cm high, 9.5 cm wide, with few hydranths, without gonophores, coll. R. Grigg, BPBM D519 .– Hawaiian islands : trawl, “Valiant Maid” (no other locality data), one colony, 5 cm high, 6 cm wide, without hydranths and gonophores, BPBM D518 .– Island of Hawaii: 19º11’N, 155º24.5’W, 260 fm (475 m), on lava, pipe dredge with tangles, R/ V Proteus, Sn. 107, Stanford Oceano. Exped. 23, leg 2, 6.ix.1971, one colony, 5.5 cm high by 5.9 cm wide, without hydranths and gonophores, BPBM (without collection number).–Island of Hawaii: Puako, on dropoff directly in front of #45 Puako Road, from roof of fairly bright cave, 40 ft (12 m), two colonies, 4.5 cm high × 5.5 cm wide and 6.0 cm high × 7.0 cm wide, without gonophores, coll. E.D. Chave, BPBM (without collection number).– Oahu: inside Mokumanu Islands , 21º27.82’N, 157º43.09’W, 45 ft (14 m), on ledges, 2.xi.1976, one colony, 5.0 cm high × 4.3 cm wide, hydranths distended, with gonophores, coll. W.J. Cooke, BPBM (without collection number).– Oahu: Lanai Lookout, in cave, 20 ft (6 m), 25.i.1997, one colony, 3.5 cm high × 8.6 cm wide, with gonophores, coll. J.P. Hoover, ROMIZ B3038 .– Kahoolawe: Kuheia Bay offshore, 10 m, under ledge, 13.i.1998, one colony, 4.3 cm high × 7.6 cm wide, with hydranths and male gonophores, coll. R. DeFelice, S. Coles and J. Smith, BPBM (without collection number) .

Description. Hydroid colonies erect, robust, fan-shaped to shrubby, extensively branched in one plane, reaching 13 cm high, 9.5 cm wide, arising from a flattened base with an outward-extending rootlike system of trabecular hydrorhizae. Hydrocaulus and hydrocladia thick, gradually thinning distally, round to irregularly round in cross-section, comprising a woody, spongy, trabecular network of chitinous fibers permeated by and overlaid with naked coenosarc; chitinous hydrophores and spines present. Hydrophores irregularly spaced and variably developed, most occurring on opposite sides of hydrocladia, comprising a pair of thorns flanking a hydranth; thorns triangular with apex blunt to pointed, sometimes reduced to low ridges on trabeculae. Spines slender, fragile, of varied length, particularly abundant and conspicuous on hydrorhizae, occasionally present elsewhere. Hydranths arising from coenosarc, most frequent on opposite sides of hydrocladia, clavate with dome-shaped hypostome, about 0.4–1.0 mm high; oral region with a whorl of 3–5 capitate tentacles; body with a varied number (ca. 8–12) of scattered capitate tentacles. In ethanol-preserved material, older and thicker parts of colony dark brown; younger and distalmost parts golden to whitish; coenosarc, hydranths, and sporosacs white.

Gonophores fixed sporosacs arising singly on short pedicels from coenosarc adjacent to hydranths, usually occurring amongst hydranths on opposite sides of hydrocladia; tentacles undeveloped.

Nematocysts ( Vervoort 1962; Millard 1975; Bouillon et al. 1992; Watson 1999):

stenoteles: large (12.0–17.5 µm long × 10.0–14.0 µm wide)

stenoteles: small (6.3–9.4 µm long × 4.5–8.0 µm wide)

“glutinants:” (9.0 µm long × 3.0 µm wide)

isorhizas (?): (6–10 µm long × 7–9 µm wide)

Remarks. Solanderia secunda ( Inaba, 1892) , Solanderia minima ( Hickson, 1903) and S. crosslandi ( Thornely, 1908) , of the tropical and subtropical Indo-Pacific region, have been differentiated largely on the basis of supposed differences in distal skeletal structure and prominence of lateral hydrophore thorns. After examining extensive material encompassing these three morphotypes, Bouillon et al. (1992) concluded that they represent forms or varieties of a single species, S. secunda , and their opinion is adopted here. Vervoort & Vasseur (1977) had earlier suggested that the three might represent a single variable species. Specimens from Hawaii conform most closely with Solanderia secunda var. minima ( Cooke 1977; Bouillon et al. 1992).

Bouillon et al. (1992) considered records of Solanderia fusca ( Gray, 1868) outside of Australia, including Nutting’s (1905) report of Ceratella fusca from Hawaii, to be doubtful. Nutting’s hydroid, from the north coast of Maui (USNM 22271), was re-examined here and identified as S. secunda .

Detailed synonymy lists of this species have been given by Bouillon et al. (1992) and Watson (1999). Solanderia secunda can be distinguished from other currently recognized species of the genus in having a hydrophore with a pair of lateral thorns. However, these thorns vary considerably in development from one colony to another ( Vervoort & Vasseur 1977). The species is dioecious ( Vervoort 1962; Bouillon et al. 1992), and growth is evidently quite rapid ( Watson 1999).

The hydroid has been reported from cryptic habitats including overhangs, crevices in walls, and caves ( Cooke 1977; Vervoort & Vasseur 1977; Hoover 1998, 2006; Kirkendale & Calder 2003). Most materials from Hawaii examined here were from similar environments. Depth records of the species in Hawaii range from 2–475 m, but material from deep waters (BPBM, without collection number) lacked hydranths and gonophores.

The color of larger branches of this species vary from purple and deep purple to chocolate brown to ochre. Smaller branches may be mauve, creamy, or yellowish-brown. Hydranths are white; male gonophores are scarlet ( Millard 1975; Bouillon et al. 1992; Watson 1999).

Reported distribution. Hawaii. Maui: north coast, 56 fm (102 m) ( Nutting 1905, as Ceratella fusca ); no location, 120 m, as S. secunda ( Cooke 1977) .–Oahu: Kipapa Island, Kaneohe Bay, underwater cave, 3–4 m, as S. (?) minima ( Cooke 1977) ; Kipapa Island, Kaneohe Bay, as S. minima ( Bouillon et al. 1992) ; Lanai Lookout, 15 ft (5 m) ( Hoover 1998, 2006).

Worldwide. Tropical and subtropical Indo-Pacific, from the Red Sea eastward to French Polynesia; 2–475 m ( Vervoort 1962; Cooke 1977; Vervoort & Vasseur 1977; Hirohito 1988; Bouillon et al. 1992; Watson 1999; Schuchert 2003; Kirkendale & Calder 2003).

FIGURE 40. Solanderia secunda : branch with hydranths and gonophores, BPBM (without collection number). Scale equals 0.25 mm.

FIGURE 41. Solanderia misakinensis : form of a 5.7 cm high portion of a colony, RMNH 3575.

FIGURE 42. Solanderia misakinensis : branch with hydranths and a small gonophore, RMNH 3575. Scale equals 0.25

mm.