Tridentata tumida ( Allman, 1877 )

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 : 55

Tridentata tumida ( Allman, 1877)

Fig. 23A–D

Synonyms available from: Calder (1991).

Sertularia tumida Allman, 1877: 23 , pl. 16, fig. 3, 4.

not Sertularia borneensis f. parvula Vannucci, 1949: 249, pl. 3, fig. 47, 48 [= Dynamena turbinata Lamouroux, 1816 ].

Description: Only one erect unbranched colony, 20.3 mm high, without hydrorhiza or basal segment, starting from the first hinge. Internodes separated by a slightly oblique node, not quite distinct, each one with a pair of hydrothecae. Hydrothecae short, inflated, 0.26–0.29 mm high, 0.12–0.17 mm in maximum width, adnate to the stem with at least half their adcauline wall, distal free portion curved outward, except for the apical pair that are directed upward. Adcauline wall convex, abcauline straight, slightly convex in the apical pair. Pairs of hydrothecae of the basal stem internodes do not touch at their adcauline wall; however, toward the distal portion of the stem, they gradually approach at their frontal margin until touching each other from half of the stem to the last pair. Margin hydrothecal with two wide and rounded lateral cusps and a smaller median adcauline not easily visible. Operculum not seen in this material.

Material examined: SE – one infertile colony from the rainy season. CZUFS CNI-00220.

Station: SE – C2P12.

Distribution: Brazil – The species has been recorded as Sertularia tumida in Brazil. Bahia ( Grohmann et al. 2003), Espírito Santo ( Grohmann et al. 2003, Grohmann 2006), Paraná, and Santa Catarina ( Miranda et al. 2015). World distribution – considered circumglobal ( Calder 1991).

Taxonomic remarks: The only difference found between the material from Sergipe and the description of T. tumida by Calder (1991) from Bermuda is in the form of the marginal cusps. The author’s illustration shows sharp and pronounced cusps, while in the specimens from Sergipe they are rounded. Maybe this characteristic can be associated with the colony size and, consequently to its age, inasmuch as Calder (1991) refers to big stolonal and ramified colonies, larger and certainly older than ours.

Remarks: unknown substrate.

Figures

Figure 23. (A-D) Tridentata tumida: general view of the basal portion of the stem with hydrothecae (A) and the detail portions of the hydrothecae of the distal (B) medial (C), and basal (D) parts of the stem. (E) Sertularelloides cylindritheca: detail of one hydrotheca with margin renovations; (F) Thyroscyphus ramosus: detail of one hydrotheca with margin renovations and the four opercular valves; (G) Thyroscyphus marginatus: detail of a hydrotheca without operculum.