Dynamena disticha (Bosc, 1802)

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 : 50-52

Dynamena disticha (Bosc, 1802)

Fig. 21D

Synonyms available from: Calder (1991).

Sertularia disticha Bosc, 1802: 101 , pl. 29, fig. 2.

Dynamena cornicina – Vannucci Mendes, 1946, – Vannucci, 1949, 1950, 1951a, 1951b, Amaral et al., 2009.

Sertularia cornicina –Maÿal, 1973.

Dynamena disticha – Migotto, 1996: 62, fig. 12A–E.

Description:Colonies erect, up to 18 mm high, arising from a creeping hydrorhiza. Stem monosiphonic, unbranched, divided into internodes by oblique or hinged nodes. Basal segments of stem ahydrothecate, articulated with the upper part, which is composed of pairs of hydrothecae. Each pair of hydrothecae is positioned in front of an internode with the side walls connected over half their high, free distal portion curved outwards. Hydrothecae cylindrical, elongated, 0.53–0.61 mm high, 0.16–0.18 mm maximum diameter. Abcauline wall concave, adcauline straight. Hydrothecae internal base with triangular perisarcal projections. Opening oval, margin with two lateral wide cusps, and a smaller adcauline one. Operculum with two valves, one abcauline wide and one adcauline smaller. Gonotheca oval, 1.2 mm high, 0.9 mm in maximum width, five to six transverse grooves, arising from a short peduncle at the base of the stem. Nematocysts mastigophore undischarged (18.4–20.1 × 7.7–10.5 µm) and discharged (18–18.9 × 8.3–8.4 µm) in coenosarc.

Material examined: PCS – few colonies from the rainy season, one of them with one gonotheca. CZUFS CNI-00211; CNI-00315; CNI-00318; CNI-00320; CNI-00321.

Station: PCS – 2, 5, 12, 13, 15, 18.

Bottom: gravel, sand, and mud.

Distribution: Brazil – Fernando de Noronha ( Pires et al. 1992, Amaral et al. 2009), Pernambuco ( Calder and Maÿal 1998), Bahia ( Grohmann et al. 2003, 2016), Espírito Santo ( Grohmann et al. 1997, 2003), Rio de Janeiro ( Vannucci 1950, Nogueira et al. 1997, Grohmann et al. 2003, Miranda et al. 2015), São Paulo ( Vannucci Mendes 1946, Vannucci 1951a, Oliveira et al. 2006, Shimabukuro 2007, Cunha and Jacobucci 2010, Oliveira and Marques 2011, Silveira and Morandini 2011, Marques et al. 2013, Miranda et al. 2015), Paraná ( Miranda et al. 2015, Maria A. Haddad unpub. data), Santa Catarina ( Miranda et al. 2011, 2015, Bouzon et al. 2012), and Rio Grande do Sul (Paulo A. Horta unpub. data). World distribution – circumglobal in tropical, subtropical, and temperate regions ( Peña Cantero and García Carrascosa 2002).

Remarks: Found on algae.

Idiellana pristis ( Lamouroux, 1816) Fig. 21E, G–H

Synonyms available from: Vervoort (1993) and Watson (2000). Idya pristis Lamouroux, 1816: 200 , pl. 5 figs A-E.

Idiellana pristis – Migotto, 1996: 65.

Description:Colonies erect, up to 37 mm high, arising from a creeping hydrorhiza.Stem monosiphonic, straight, divided into segments by transverse nodes. The first segment ahydrothecate and the others with hydrothecae and hydrocladia. Hydrocladia 2.7–16.7 mm high, arising alternately from an apophysis, with an axillary hydrotheca and an opposite one. Hydrocladia divided into internodes by transverse nodes. Each internode with several pairs of hydrothecae adnate in more than half their high, free distal portion curved outwards. Hydrothecae elongated, 0.45–0.57 mm high, 0.12–0.14 mm in maximum width, abcauline wall concave, and the adcauline wall convex overlapping the wall of the opposite hydrothecae of each pair. Margin oval with a pair of triangular lateral lobes, operculum with two valves.Gonothecae urn-shaped, 1.13–1.20 mm high, 0.72–0.77 mm maximum diameter, with several longitudinal folds and a narrow circular distal portion, appearing in dorsal rows between the basal and medial parts of the stem. Mastigophore undischarged (21.8–22.8 × 7.8–8.5 µm) and discharged (15.5–21.6 × 7.1–9.6 µm) in coenosarc.

Material examined: PCS – few colonies, two with gonothecae, from the dry and rainy seasons; VB – one infertile colony from the dry season. CZUFS CNI-00029; CNI-00064; CNI-00212; CNI-00213.

Stations: PCS – 7, 11, 13, 16, 17; VB – C2P34.

Bottom: mud.

Distribution: Brazil – Alagoas (Maximiliano M. Maronna unpub. data), Bahia ( Allman 1888), São Paulo ( Vannucci Mendes 1946, Migotto 1996, Shimabukuro 2007, Silveira and Morandini 2011, Marques et al. 2013, Miranda et al. 2015), Paraná ( Miranda et al. 2015), and Santa Catarina ( Bouzon et al. 2012). World distribution – species well distributed from tropical to subtropical regions ( Vervoort 1993).

Remarks: Unknown substrate for the PCS material. The colony found at the Vaza-Barris River was colonizing a plate.

Salacia tetracythara Lamouroux, 1816 Fig. 22A

Synonyms available from: Bale (1884), Billard (1925), and Watson (2000).

Description: Colonies erect, 7.13 mm and 16.08 mm high, bearing alternating hydrocladia. Stems unbranched arising from a thick, short hydrorhiza, perisarc thick, two lateral rows of unconnected hydrothecae in subopposite pairs, three between successive hydrocladia (one inferior, one axillary, and one opposite). Hydrocladia straight and rigid, on a single plane, alternating, branched once in two hydrocladia. One colony bearing tendrils on all hydrocladia (average: 1.16 ± 0.75 mm). Hydrothecae in two lateral rows in opposite to subopposite pairs, members of the same pair not in contact, but successive hydrothecae of a row in contact or overlapping. Hydrothecae tubular, 0.4–0.5 mm high 0.09–0.12 mm in maximum width, adnate for nearly their entire length, slightly curved distally, aperture rounded, vertical with delicate margin showing signs of renovation, operculum composed of one oval valve attached to abcauline side. No cusps were observed on the margin. Adcauline wall of hydrothecae extended below by a triangular to ovoid adcauline space below each hydrotheca. Only one type of nematocyst was found, probably large microbasic mastigophores. Undischarged and discharged nematocysts were observed on the stem and hydrothecae. See more details in Mendonça et al. (2021).

Material examined: SE – two infertile colonies from the rainy season. CZUFS CNI-00065; CNI-00066.

Stations: SE – C2P12; C2P56.

Distribution: Brazil – Sergipe ( Mendonça et al. 2021). World distribution – Australian tropical to temperate east and southeast coast ( Lamouroux 1816, Bale 1884, Watson 2000), Indian Ocean ( Rees and Vervoort 1987, Schuchert 2003), tropical and subtropical regions of Indo-Pacific ( Billard 1925, Gibbons and Ryland 1989, Gravier-Bonnet 2008), and China Sea ( Song 2016).

Remarks:Colonizing the plate. Considered an alien species to the Atlantic Ocean ( Mendonça et al. 2021).

Figures

Figure 21. (A) Amphisbetia distans: detail of a stem with few hydrothecae and one gonotheca; (B-C) Diphasia digitalis: (B) general view of a stem; (C) detail of two pairs of hydrothecae; (D) Dynamena disticha: detail of a stem with two pairs of hydrothecae and one gonotheca; (E, G-H) Idiellana pristis: (E) detail of the hydrocladium with three pairs of hydrothecae; (G) detail of a stem with few gonothecae (red arrows); (H) detail of two gonothecae; (F) Diphasia tropica: detail of a stem with three pairs of hydrothecae; (I) Dynamena crisioides: detail of a stem with few hydrothecae.

Figure 22. (A) Salacia tetracythara: general view of a stem showing few hydrocladia and hydrothecae; (B) Tridentata loculosa: detail of the stem with two hydrocladia and few hydrothecae; (C-E) Tridentata marginata: (C) general view of a stem with two gonothecae (red arrows); (D) detail of a stem with few hydrocladia and hydrothecae; (E) detail of one gonotheca; (F, I) Tridentata rugosissima: (F) detail of one pair of hydrothecae; (I) general view of a stem with several hydrothecae; (G-H) Tridentata turbinata: (G) detail of one pair of hydrothecae; (H) detail of a stem with hydrothecae.