Pennaria disticha Goldfuss, 1820

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 7

Pennaria disticha Goldfuss, 1820

Fig. 1a

Pennaria disticha Goldfuss, 1820: 89 .

Pennaria tiarella .— Fraser, 1933: 261; 1944: 86.— Weiss, 1947: 57; 1948: 158.— Winston, 1982: 164.

Pennaria sp. — Cummings, 1994: 1208.

Halocordyle disticha .— Jones, 2002: 218.

Type locality. Italy: Gulf of Naples. Goldfuss (1820) gave the provenance of this species simply as “Im Mittelmeer,” but his record was based on Cavolini’s (1785: 134) “ Sertolara pennara ” [not Sertularia pennaria Linnaeus, 1758 ] from the Gulf of Naples area.

Voucher material. Fort Pierce Inlet , north jetty, north side, 27°28’24.2”N, 80°17’20.3”W, 0.1 m, 15.ii.1991, 20° C, collected manually, one colony, 5 cm high, without gonophores, coll. D.R. Calder, ROMIZ B1118 .

Remarks. Globiceps tiarella Ayres, 1854 (type locality: Sag Harbor, Long Island, New York), Eucoryne elegans Leidy, 1855 (type locality: Point Judith, Rhode Island), Pennaria gibbosa L. Agassiz, 1860 (type locality: Key West, Florida; see A. Agassiz 1965) and P. inornata Brooks, 1883 (type locality: Fort Macon, North Carolina) are generally considered to be conspecific with P. disticha Goldfuss, 1820 from the Mediterranean (e.g. Calder 1988), although molecular work is needed to confirm the supposed synonymy. A large, familiar, and distinctive hydroid, P. disticha has often been used in experimental studies ( Schuchert 2006). Contact with colonies of this species may result in a relatively painful sting.

Pennaria disticha , prevalent in tropical and warm-temperate areas of the western Atlantic ( Fraser 1944; Calder 1988), may become dormant at water temperatures between 15–20° C ( Calder 1990). Colonies from Fort Pierce Inlet, collected during winter at 20° C, were active but lacked gonophores. A euryhaline species, it extends from oceanic salinities to about the 20‰ isohaline in estuaries (Calder 1976). The form of the colony is strongly influenced by environmental conditions; those from areas exposed to waves are typically small and compact while those from sheltered areas tend to be larger and more slender ( Calder 1988). The life cycle includes a short-lived medusoid stage that may or may not be released from the hydroid ( Hargitt 1900; Brinckmann-Voss 1970). In the western Atlantic, P. disticha has been reported as far north as the coast of Maine ( Mayer 1910), where it would be active only during summer. The hydroid is restricted bathymetrically to shallow waters (0–29 m) ( Fraser 1944).

Descriptions and recent discussion of the species have been provided by Schuchert (2006) and Calder (2010).

Reported distribution. Atlantic coast of Florida. Talbot Island, from stomach of a Black Scoter ( Fraser 1933, 1944, as Pennaria tiarella , from “Tablot” Island).—Biscayne Bay ( Weiss 1947, 1948, as Pennaria tiarella ).— Sebastian Inlet ( Winston 1982, as Pennaria tiarella ).—Boca Raton ( Cummings 1994, as Pennaria sp. ).—Biscayne Bay ( Jones 2002, as Halocordyle disticha ).

Western Atlantic. Maine ( Mayer 1910, as Pennaria tiarella ) to Brazil (Oliveira et al. submitted), including Bermuda ( Calder 1988), the Gulf of Mexico ( Calder & Cairns 2009), and the Caribbean Sea ( Galea 2008).

Elsewhere. Thought to be circumglobal in tropical and warm-temperate waters ( Calder 2010).

Figures

FIGURE 1. a, Pennaria disticha: part of hydrocaulus with annulated pedicel and juvenile hydranth, ROMIZ B1118; scale equals 0.5 mm. b, Cladocoryne floccosa: stem and hydranth, ROMIZ B1114, scale equals 0.5 mm. c, Velella velella: juvenile, left-sailing form, ROMIZ B1113, scale equals 1 mm. d, Zanclea alba: pedicel and hydranth, ROMIZ B3961, scale equals 0.25 mm. e, Solanderia gracilis: tip of branch with three hydranths, ROMIZ B3962, scale equals 0.25 mm. f, Turritopsis fascicularis: pedicel and hydranth with medusa bud, ROMIZ B1106, scale equals 0.25 mm. g, Parawrightia robusta: part of pedicel and hydranth, ROMIZ B1110, scale equals 0.25 mm. h, Bimeria vestita: pedicel and hydranth, ROMIZ B1116, scale equals 0.25 mm. i, Eudendrium carneum: part of hydrocaulus with pedicel and hydranth, ROMIZ B3960, scale equals 0.25 mm.