Dicoryne sp.

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 : 10-12

Dicoryne sp.

Fig. 4F–G

Description: Colonies erect, up to 1.24 mm high. Stem monosiphonic, 44–95 µm in diameter, increasing from the base to the distal portion, branched somewhat alternately. Perisarc moderately thick, encrusted with silt, wrinkled in some parts, and annulated at the base of the stem and branches. The perisarc end at the base of the hydranth covers only its basal part not forming a pseudohydrotheca. Hydranths fusiform, 0.16–0.24 mm high, 0.07–0.09 mm wide, with a conical hypostome. A whorl of 10–12 filiform tentacles just at the base of the hypostome. Only one reproductive colony with oval sporosacs 205–284 µm high and 108–220 µm wide, on short pedicels in a branch just below the insertion of the hydranth. A single egg per gonophore.

Taxonomic comments: There are only two valid Dicoryne species ( Schuchert 2007), D. conferta (Alder, 1856) and D. conybearei (Allman, 1864) . According to Schuchert (2007), the two species are not easily distinguishable. As distinctive features, the author mentioned the presence of two tentaculozooids on the sporosacs, and female sporosac with two eggs in D. conferna , and one or two tentaculozooids and one egg for D. conybearei . These distinctive characteristics are variable, according to the author, making it even more difficult to distinguish between the two species.

Material examined: VB – few infertile colonies from the dry and rainy seasons; SE – few colonies, one of them with gonophores, from the dry season.

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

Remarks: Colonizing the plate, Ostreidae , and the hydroids Pennaria disticha and Nemalecium lighti .

Figures

Figure 4. (A-B) Bimeria vestita: (A) general view of a stem with hydranths and gonophores; (B) detail of the distal region of the stem showing the hydranths and gonophores (red arrows); (C-D) Calyptospadix cerulea: (C) detail of the stem showing hydranths and gonophores (red arrows); (D) general view of a colony; (E) Bougainvillia muscus: detail of a stem showing hydranths and gonophores (red arrows); (F-G) Dicoryne sp.: (F) detail of a polyp with hydranths and gonophores (red arrows); (G) general view of a colony.