Obelia cf. dichotoma (Linnaeus, 1758)

Mendoza-Becerril, María A., Murillo-Torres, Paulina, Serviere-Zaragoza, Elisa, León-Cisneros, Karla, Mazariegos-Villarreal, Alejandra, López-Vivas, Juan Manuel & Agüero, José, 2024, First records of hydroid epibionts on the introduced macroalga Gracilaria parvispora in the Mexican Pacific, Biodiversity Data Journal 12, pp. e 130248-e 130248 : e130248-

Obelia cf. dichotoma (Linnaeus, 1758)

Materials

Type status: Other material. Location: locality: La Concha ; minimumDepthInMeters: 0.5; maximumDepthInMeters: 1; Event: year: 2021; month: 6; day: 19; habitat: apical macroalgae regions; Record Level: dataGeneralizations: 18 ° C; 36 PSU

Type status: Other material. Location: locality: UABCS Pichilingue ; minimumDepthInMeters: 0.0; maximumDepthInMeters: 1; Event: year: 2021; month: 7; day: 15; habitat: basal macroalgae regions; Record Level: dataGeneralizations: 28 ° C; 36 PSU

Type status: Other material. Location: locality: La Concha ; minimumDepthInMeters: 0.5; maximumDepthInMeters: 1; Event: year: 2022; month: 2; day: 11; habitat: all macroalgae regions; Record Level: dataGeneralizations: 18 ° C; 36 PSU

Notes

Fig. 6 e

Type locality. Southwest England ( Cornelius 1975).

Detailed description in Mendoza-Becerril et al. (2020).

Taxonomic status. Accepted. AphiaID 117386.

Remarks. It is now widely accepted and supported that the traditional concept of O. cf. dichotoma (cf. Cornelius (1995)) comprises multiple cryptic lineages ( Calder 2013, Calder et al. 2014, Cunha et al. 2017 a, Calder et al. 2019, Cunha et al. 2020) and in the eastern Pacific, affinities still need to be determined between local populations ( Calder et al. 2019), mainly because their lineages are not distinguished from each other by morphometric analyses ( Cunha et al. 2020). Therefore, molecular studies will be necessary to delimit the eastern Pacific lineages.

Diagnosis

Colonies erect, sympodial, in some cases with first-order branches. Exoskeleton thin. Stem monosiphonic, divided into internodes at regular intervals. Internodes with annulations at the base and one distal apophysis alternately given off the hydrothecal pedicel. Hydrotheca short and conical, with diaphragm oblique and margin entire. Hydrothecal pedicel with annulations along its whole length. With conical gonothecae with a short distal neck, arising from the base of the hydrothecal pedicel or the axis of the main stem and branches.

Figures

Figure 6. Hydrozoan epibionts. a Corydendrium sp.: part of hydrocaulus with two hydranths, scale equals 0.5 mm; b Ventromma halecioides: part of a hydrocaulus with the proximal end of a hydrocladium, hydrothecae, nematothecae, scale equals 0.3 mm; c Plumularia floridana: part of a hydrocaulus with the proximal end of a hydrocladium, hydrothecae and nematothecae, scale equals 0.1 mm; d Clytia linearis: part of hydrocaulus with hydrothecae, scale equals 0.8 mm; e Obelia cf. dichotoma: part of hydrocaulus with hydrothecae, scale equals 0.2 mm; f Obelia oxydentata: part of hydrocaulus with hydrothecae, scale equals 0.3 mm; g Obelia tenuis: part of hydrocaulus with a hydrotheca, scale equals 0.1 mm.