Pennaria disticha Goldfuss, 1820

Castro Mendonça, Luana M., Parisotto Guimarães, Carmen R. & Haddad, Maria A., 2022, Taxonomy and diversity of hydroids (Cnidaria: Hydrozoa) of Sergipe, Northeast Brazil, Zoologia (e 21032) 39, pp. 1-65 : 8

Pennaria disticha Goldfuss, 1820

Synonyms available from: Calder (1988) and Schuchert (2006). Pennaria disticha Goldfuss, 1820: 89 . Halocordyle sp. – Vannucci, 1950; Halocordyle fragilis – Vannucci, 1951a, 1951b. Halocordyle disticha – Migotto and Silveira, 1987, – Pires et al.,

1992, – Grohmann, 1997, – Grohmann et al., 1997, –Kelmo and Santa Isabel, 1998, – Amaral et al., 2009.

Description: Colonies erect up to 9.9 cm high. Stem monopodial with alternating branches forming a feather-like structure, arising from a branched and creeping hydrorhiza. Main axis monosiphonic formed by a thick stem, 0.26–0.53 mm wide. Perisarc thick, smooth, with an annulated portion at somewhat regular intervals, usually above the insertion of the hydrocladium and also on the hydranth pedicels. Hydrocladia 15–20 mm high, 0.14–2.18 mm wide, arising from the stem at angles of 105.2 and 144.8 °, carrying hydranths on pedicels. Hydranth pedicels evenly spaced, completely annulated, or only at the base. All hydranth pedicels of the same hydrocladium with approximately the same height and diameter. In some colonies, two pedicels were emerging from the same point on the hydrocladium. Hydranths pear-shaped, 0.33–0.87 mm high, 0.1–0.41 mm wide, with a dome-shaped hypostome. A whorl of 8 to 11 filiform tentacles around the aboral region and 8 to 12 short capitate tentacles distributed in the distal region of the hydranth in two whorls, one oral and the other approximately in the middle of the hydranth. Two to four medusoid-type gonophores per hydranth, 0.23–1.1 mm high, 0.13–0.53 mm wide, arising from a short pedicel just above the aboral tentacles. Nematocysts stenoteles of various sizes: undischarged (11.1–26.7 × 9.4–17.6 µm).

Material examined: VB – abundant colonies with and without gonophores from the dry and rainy seasons; SE – abundant colonies with and without gonophores from the dry and rainy seasons; CZUFS CNI-00041; CNI-00073; CNI-00074; CNI-00075.

Stations: VB - C1P12, C1P34, C1P56, C2P12, C2P56, C3P34, C3P56; SE - C1P12, C1P34, C1P56, C2P34, C2P56, C3P34, C3P56.

Distribution: Brazil – Ceará ( Marques et al. 2006, Shimabukuro et al. 2006), Fernando de Noronha ( Pires et al. 1992, Amaral et al. 2009), Pernambuco ( Calder and Maÿal 1998, Oliveira et al. 2009, abstract), Bahia ( Kelmo and Santa-Isabel 1998, Grohmann et al. 2003), Espírito Santo ( Vannucci 1950, 1951a, 1951b, Grohmann et al. 1997, 2003), Rio de Janeiro ( Vannucci 1950, 1951a, 1951b, Grohmann et al. 2003; 2011), São Paulo ( Silveira and Morandini 2011; Fernandez et al. 2014), and Paraná ( Bumbeer and Rocha 2012). World distribution – circumglobal from warm temperate to tropical waters ( Gravili et al. 2015).

Taxonomic remarks: Pennaria disticha is considered a complex of cryptic species based on the result of mitochondrial 16S analysis ( Miglietta et al. 2015, 2018).

Remarks: Colonies with gonophores were found only during the dry period. Found colonizing the plates, Bryozoa, barnacles (Cirripedia), Ostreidae , Polychaeta tubes, Ascidiacea, and the hydroid Corydendrium parasiticum .