Pennaria disticha Goldfuss, 1820

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 63-66

Pennaria disticha Goldfuss, 1820

Fig. 43

Pennaria disticha Goldfuss, 1820: 89 .— Hoover, 1998: 20, fig.; 2006: 20, fig.– Coles et al., 2006: 494. Pennaria sp. — Edmondson, 1933: 23, figs. 11, 12a; 1946: 24, figs. 12, 13a. Corydendrium splendidum Boone, 1938: 33 , pl. 4. Pennaria tiarella .— Edmondson & Ingram, 1939: 256.– Chu & Cutress, 1954: 9.— Josephson, 1961: 565.— Mariscal &

Lenhoff, 1969: 330.— Pardy & Lenhoff, 1968: 197, figs. 1–3.— Rees et al., 1970: 309, figs. 1, 2.— Reed, 1971:

48.— Pardy, 1971: 84, figs. 1–3.— Rees, 1971: 119, figs. 1, 2.— Long, 1974: 27. Halocordyle disticha .— Cooke, 1977: 80, fig. 8.— Coles et al., 1999: 150.

Type locality. Italy: Gulf of Naples ( Goldfuss 1820) .

Material examined. Oahu : Kaneohe Bay, 29.x.1929, indeterminable number of colonies and colony fragments (dry), coll. C.H. Edmondson, BPBM D182 .– Oahu : Pearl Harbor, 30.xi.1929, about 20 colonies and colony fragments, up to 7 cm high, detached, without gonophores, coll. C.H. Edmondson, BPBM D183 .– Oahu : Kaneohe Bay, 1936 (no month or day given), one colony with numerous stems, to 12 cm high, with gonophores, BPBM D216 .– Oahu : Kaneohe Bay, 1939 (no month or day given), seven colony fragments, up to 10 cm high, with gonophores, BPBM D230 .– Oahu : Honolulu Harbor, 5.v.1944, 14 colony fragments, to 13 cm high, with gonophores, coll. C.H. Edmondson, BPBM D251 .– Oahu : Honolulu Harbor, 8.xi.1944,>25 colony fragments, in poor condition, to 5 cm high, with a few gonophores, coll. C.H. Edmondson, BPBM D254 .– Oahu : Honolulu Harbor, 2.vi.1945, 8 colony fragments, to 8.5 cm high, without gonophores, BPBM D259 .– Oahu : Honolulu Harbor, 5.vi.1945, 3 colony fragments, to 3 cm high, without gonophores, BPBM D264 .– Oahu : Honolulu Harbor, 9.iv.1946, four colony fragments, in poor condition, to 11 cm high, gonophores not apparent, BPBM D270 .– Oahu , Honolulu Harbor, 16.vii.1946, indeterminable number of colonies and colony fragments (dry), coll. C.H. Edmondson, BPBM D273 .– Oahu : Honolulu Harbor, 11.xi.1947, one large colony with many stems, to 11.5 cm high, with gonophores, coll. C.H. Edmondson, BPBM D279 .– Oahu : Honolulu Harbor, 3.xii.1947, on test blocks, one large colony with several stems, in poor condition, to 12 cm high, without apparent gonophores, coll. C.H. Edmondson, BPBM D282 .– Oahu : Pearl Harbor, 15.iv.1948, on bottom of motile dry dock, five colony fragments, up to 12 cm high, with gonophores, coll. C.H. Edmondson, BPBM D289 .– Oahu : Honolulu Harbor, Pier 28, 6.iii.1952, one colony with several stems, to 12.5 cm high (label states: “ Growth Record — 5 inches in 90 days”), with gonophores, BPBM D325 .– Oahu : Kaneohe Bay, Checker Reef, 2 m, 19.v.1976, three fouled colony fragments in poor condition, up to 4.5 cm high, removed from Porites , with a few gonophores, coll. J.G. Grovhoug, BPBM (without collection number) .– Oahu : Kaneohe Bay, Checker Reef, 2 m, 21.v.1976, two fouled colony fragments in poor condition, up to 5 cm high, removed from Porites , with a few gonophores, coll. J.G. Grovhoug, BPBM (without collection number) .– Oahu : Pearl Harbor, Rainbow Bay Marina , docks and shoreline, 0–1 m, 11.i.1996, three colony fragments, without gonophores, coll. R. DeFelice, BPBM D1043 .– Oahu : Pearl Harbor, N side of entrance channel, 0.5– 3 m, 13.ii.1996, one colony with three stems, to 5 cm high, without gonophores, coll. R. DeFelice, BPBM D1045 .– Oahu : Pearl Harbor , sheet piling in thermal discharge from Hawaiian Electric Company ( HECO) Waiau plant, 0–1.5 m, 21.iii.1996, six colony fragments, to 10 cm high, all dead, coll. R. DeFelice, BPBM D1050 .– Oahu : Pearl Harbor, Middle Loch, on hull of floating drydock USS “Machinist”, 0.5– 5 m, 27.iii.1996, two colony fragments, to 8 cm high, lacking hydranths and gonophores (vial also contains a colony of Bougainvillia muscus ), coll. R. DeFelice, BPBM D1052 .– Oahu : Pearl Harbor, SE Loch, E of drydock area, 0.5– 6 m, 3.iv.1996, 16 colony fragments, to 8 cm high, all dead, coll. R. DeFelice, BPBM D1056 .– Oahu : Pearl Harbor, N side of SE Loch entrance, 0.5– 3 m, 2.iv.1996, one colony in two parts, with few hydranths, 7 cm high, no gonophores, coll. R. DeFelice, BPBM D1058 .– Oahu : Pearl Harbor, adjacent to Hospital Point Drydock Number 4, 0.5– 3 m, 30.iv.1996, four colony fragments, to 4 cm high, in poor condition, no gonophores, coll. R. DeFelice, BPBM D1062 .– Oahu : Kewalo Basin, Fisherman’s Wharf, 16.vii.1998, one colony with numerous stems, to 14.5 cm high, with gonophores, coll. R. deFelice and S. Coles, BPBM (without collection number) .– Oahu : Ala Wai Harbor, Hilton Lagoon discharge pipe, 30.vii.1998,>30 colonies and colony fragments, up to 11 cm high, detached, with a few gonophores, coll. R.C. DeFelice and S.L. Coles, BPBM D1110 .– Lisianski , Northwest Hawaiian Islands: LIS–10, 16.ix.2002, about 25 colonies and colony fragments, up to 6 cm high, detached, with gonophores, BPBM D1173 .– Pearl and Hermes Reef, Northwest Hawaiian Islands: PHR–24, 26.ix.2002, six colonies and colony fragments with few hydranths, up to 7.5 cm high, detached, with a few gonophores, BPBM D1178 .– Lisianski , Northwest Hawaiian Islands: LIS–11, 29.ix.2002, about 10 colonies and colony fragments, up to 8 cm high, detached, with gonophores, BPBM D1182 .– Oahu : Pearl Harbor, Rainbow Bay Marina , 21º22’16.52”N, 157º56”19.75” W, on buoy out from docks, 1 m, 16.vii.09, one colony with two stems, 4.5 cm high, with developing gonophores, coll. D.R. Calder, ROMIZ B3829 .

Description. Hydroids colonial, erect, large, up to 22 cm high, arising from a creeping and twisted hydrorhiza. Hydrocaulus monosiphonic, alternately branched, straight to slightly curved, annulated just above each hydrocladium, otherwise smooth. Hydrocladia nearly straight to curved, annulated at proximal end and distal to each ultimate branchlet; ultimate branchlets of varied length but usually quite short, annulated basally, straw-coloured, bearing a neck region with a hydranth at distal end. Perisarc quite thick except at distal ends of hydrocaulus, hydrocladia, and ultimate branchlets, terminating at hydranth base. Hydranths bowling-pin-shaped with rounded base, about 1.5 mm high, 0.5 mm wide, bearing a single whorl of long, slender, slightly capitate tentacles aborally, remainder of hydranth armed with much shorter, strongly capitate tentacles, 4–6 of these being arranged in an oral whorl; aboral tentacles reaching to 2 mm long, usually 12–16 in number; hypostome large, knob-shaped. Hydranth body orangy with scattered ochre patches, especially above aboral tentacle whorl; hypostome whitish; hydrocaulus black except at distal extremity; hydrocladia black basally, straw-coloured to clear distally.

Gonophores eumedusoids, arising just distal to aboral tentacles. Eumedusoids thimble-shaped; radial canals four; tentacle bulbs four, rudimentary; manubrium simple, tubular, reaching nearly to velar opening; gonads on manubrium, filling subumbrellar cavity when mature.

Remarks. Pennaria disticha Goldfuss, 1820 is one of the most conspicuous shallow-water hydroids in the Hawaiian archipelago, and it is the most frequently reported species from the islands. It occurs on all the main islands of Hawaii, and extends westward to Midway Atoll ( Carlton & Eldredge 2009). As is apparent from the material examined above, colonies are active in waters of the region throughout the year.

The taxonomy and general biology of this large, distinctive, and relatively well-known hydroid have recently been reviewed by Schuchert (2006). A synonymy list of the species, under the name Halocordyle disticha , has been given in an earlier report ( Calder 1988). The cnidomes of both hydroid and attached medusoid stages were described in the same report. Numerous other accounts of the nematocyst complement of P.disticha exist, including those by Weill (1934), Millard (1975), García-Corrales & Aguirre (1985), da Silveira & Migotto (1991), Östman et al. (1991), Schuchert (1996), and Watson (1999).

Occurring in shallow tropical and temperate areas worldwide, this highly successful invasive species has been reported across the Indo-Pacific on continental shores from South Africa ( Millard 1975) and the Red Sea ( Hirohito 1977) to the west coast of the Americas ( Fraser 1946), and on islands such as Zanzibar and Pemba ( Jarvis 1922), Juan de Nova Island ( Gravier-Bonnet & Bourmaud 2006), Madagascar ( Gravier 1970), the Seychelles ( Millard & Bouillon 1973), the Mergui Archipelago ( Ritchie 1910a), Christmas Island ( Ritchie 1910b), Indonesia ( Pictet 1893; Vervoort 1941; Schuchert 2003), the Philippines ( Hargitt 1924), Japan ( Yamada 1959; Hirohito 1969, 1974, 1988), Palau ( Hirohito 1977: 9), Guam ( Kirkendale & Calder 2003), Enewetak Atoll ( Cooke 1975), New Caledonia ( Gravier-Bonnet 2007), New Zealand ( Schuchert 1996), Fiji ( Gibbons & Ryland 1989), Hawaii ( Cooke 1977), and the Galápagos ( Fraser 1938a; Calder et al. 2003), among others.

The hydroid of Pennaria disticha is widely known to be eurytopic. It thrives in oceanic salinities but also penetrates into estuaries approximately to the 20‰ isohaline ( Calder 1976). While hydroids may be active throughout the year in tropical and subtropical regions (Schuchert 2006), they become dormant during cold periods in temperate regions ( Hargitt 1900; Brinckmann-Voss 1970; Calder 1990). Bathymetrically, P. disticha is generally restricted to waters of less than 30 m, and is most abundant in the immediate subtidal region. In Bermuda, it was one of the most common species of hydroids in samples from 0–25 m, but it was absent in all samples below that depth range (Calder 1998). Gonophores are eumedusoids, sometimes remaining fixed and sometimes liberated from the hydroid ( Hargitt 1900; Brinckmann-Voss 1970). When released, the free eumedusoids are short-lived (surviving a few hours at most) and liberated during evening hours ( Hargitt 1900; Baker 1936; Brinckmann-Voss 1970; Calder 1988; Genzano & Kubota 2003). Hoover (1998, 2006) reported that colonies reach about 12 inches (30 cm) high in Hawaii, and specimens up to 22 cm high were observed during this study on a pier at the Hawaii Institute of Marine Biology on Coconut Island in Kaneohe Bay.

Pennaria disticha has been utilized frequently in morphological and experimental studies on invertebrates (Schuchert 2006), often under the name P. tiarella . Its hydroid is venomous to humans ( Halstead 1988).

Pennaria wilsoni Bale, 1913 of Australia ( Watson 1996), Fiji ( Gibbons & Ryland 1989) and Guam ( Kirkendale & Calder 2003) somewhat resembles P. disticha , but differs in having a single distal whorl of capitate tentacles on the hydranths, and in having hydrocladia that are spirally branched and not pinnate ( Hirohito 1988: 30, fig. 9e).

Recorded distribution: Hawaii. Oahu: Kaneohe Bay ( Boone 1938, as Corydendrium splendidum ). Oahu: Kaneohe Bay ( Mariscal & Lenhoff 1969). Oahu: Kaneohe Bay ( Josephson 1961). Oahu: Kaneohe Bay ( Pardy & Lenhoff 1968; Pardy 1971; Reed 1971; as Pennaria tiarella ). Oahu: Kaneohe Bay ( Rees et al. 1970, as Pennaria tiarella ). Oahu: Pearl Harbor, off Ewa Beach, and off Barber’s Point ( Long 1974, as Pennaria tiarella ). Oahu: Kaneohe Bay; Ala Wai Yacht Harbor, Kewalo Basin, Honolulu Harbor, Keehi Marina ( Cooke 1977) . Oahu: Kaneohe Bay and Lanai Lookout, 20 ft (6 m) ( Hoover 1998, 2006). Oahu: Pearl Harbor ( Coles et al. 1999, as Halocordyle disticha ).

Worldwide. Circumglobal in tropical and warm temperate waters; 0–29 m ( Millard 1975; Calder 1988; Watson 1999; Schuchert 2006; Calder & Cairns 2009).

Figures

FIGURE 43. Pennaria disticha: hydrocaulus, branch, and two hydranths with developing eumedusoids, ROMIZ B3829. Scale equals 1mm.