Ectopleura dumortierii (Van Beneden, 1844)

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 : 3-6

Ectopleura dumortierii (Van Beneden, 1844)

Fig. 2A–C

Synonyms available from: Schuchert (2010).

Tubularia dumortierii Van Beneden, 1844: 50 , pl. 2.

Ectopleura dumortierii : Migotto, 1996: 24.

Description: Hydroids solitary or forming groups of 2 to 11 individuals, up to 18.3 mm high. Stem long, with 3.4 to 18.3 mm high, arising from a simple and creeping hydrorhiza, without ramifications, isodiametric throughout or slightly widening distally. Stem with perisarc smooth or with annulations, and those, when present in a number of 2 to 7, disposed in irregular intervals. The “neck” (the region between the stem and hydranth) with approximately the same length as the hydranth. Hydranth balloon or pear-shaped, 0.4–0.63 mm high and 0.2–0.5 mm wide, with one whorl of 9–12 filiform oral tentacles and one whorl of 12 filiform aboral tentacles. One juvenile individual was found with a whorl of 8 capitate tentacles in the oral region and 12 filiform in the aboral one. The majority of the polyps found were without hydranths. Gonophores oval-shaped, 62–93 µm high, 29–66 µm wide, found in two solitary individuals arising between the aboral tentacles. Two types of nematocysts were observed, both from the coenosarc region of the stem: small stenoteles undischarged (5.3–7.9 × 2.8–7.5 µm) and discharged (5–7.2 × 4.6–4.9 µm); a big one discharged (9.6 × 8 µm); and anisorhiza undischarged (7.3–9.4 × 2.3–3.6 µm).

Material examined: VB – several polyps, two of them with gonophores, from the dry and rainy seasons; SE – infertile polyps from the dry and rainy seasons. CZUFS CNI-00039; CNI-00068; CNI-00069; CNI-0070.

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

Distribution: Brazil – Sergipe (medusa, Araújo 2006), São Paulo ( Migotto and Silveira 1987, Migotto 1996, Silveira and Morandini 2011, Oliveira et al. 2016), and Paraná ( Bumbeer and Rocha 2012, Nagata et al. 2014, Cabral and Nogueira-Junior 2019). World distribution – Schuchert (2010) stated that the polyp and medusa of E. dumortierii has a huge distributional range, including the Atlantic coast of Europe, the Occidental Atlantic (from Cape Cod to South Carolina), and the Mediterranean. Schuchert considers as doubtful the records from the tropical Atlantic, Indian Ocean, and the Pacific Ocean, also stating that these records could be from a different species. Schuchert also cited Galea (2007) who describes E. dumortierii from Chile as “indistinguishable from specimens from Europe”, but molecular analysis (16S, not published) showed a distinction between the Chilean and European specimens. However, in recent years, E. dumortierii has been recorded in the Pacific Ocean in several works from Galea and coauthors (e.g. Galea et al. 2009, Galea and Schories 2012). The polyp of E. dumortierii also has records from the Atlantic coast of Colombia and the medusa from the Pacific (between Colombia and Chile) and Atlantic ( Brazil and Uruguay) (see specific records in Oliveira et al. 2016).

Remarks: Polyps found colonizing the plates and also on Ascidiacea, Polychaeta tubes, and the hydroid Pennaria disticha . Other hydroids were found colonizing E. dumortierii , such as Clytia gracilis , Bimeria vestita , Cladocoryne floccosa (with gonophores), and Obelia oxydentata (with gonothecae). Ectopleura dumortierii was found with gonophores only in the dry season.

Figures

Figure 2. (A-C) Ectopleura dumortierii: (A) general view of a polyp; (B) detail of the neck region (Ne - red arrow) and hydranth with gonophores (Go - red arrows); (C) detail of the distal region of a polyp showing the neck (Ne - red arrow) and the hydranth.