Diphasia digitalis (Busk, 1852)

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 : 49

Diphasia digitalis (Busk, 1852)

Fig. 21B–C

Synonyms available from: Watson (2000).

Sertularia digitalis Busk, 1852: 387 , 393.

Nigellastrum digitale – Vannucci 1949, 1951a [polyp].

Diphasia digitalis – Maÿal, 1983: 7.

Description: Colonies erect, up to 32 mm high, arising from a creeping and tubular hydrorhiza. Stem monosiphonic, composed of several internodes. First internode long, ahydrothecate, separated by a transverse node. Hydrocladia 7.5–23.1 mm long, arising from the stem at angles of 97.7–137.6 °, also composed of internodes. Stem and hydrocladia with a pair of hydrothecae per internode. Hydrothecae tubular, elongate, 0.85–0.99 mm high, 0.24–0.27 mm in maximum width, expanding from the base to the distal portion, adnate to internode for more than half their high, free end portion slightly curving outward. The adnate portion of paired hydrothecae in contact. Margin quadrangular, operculum with a wide acauline valve.

Material examined: VB – few infertile colonies from the dry and rainy seasons. CZUFS CNI-00062; CNI-00207.

Stations: VB – C1P56, C2P12, C2P34, C3P56.

Distribution: Brazil – Bahia ( Nutting 1904), Pernambuco ( Maÿal 1983, Calder and Maÿal 1998), Rio de Janeiro ( Vannucci 1949, 1951a, Miranda et al. 2015), São Paulo ( Silveira and Morandini 2011, Fernandez et al. 2014), and Santa Catarina ( Bouzon et al. 2012). World distribution – circumglobal in tropical and subtropical regions ( Watson 2000).

Remarks: Colonies large, mainly colonizing the plates, and partially on Polychaeta tubes, Bryozoa, Ascidiacea, and the hydroids Corydendrium parasiticum and Pennaria disticha .

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.