Bimeria vestita Wright, 1859

Cruz-Gómez, Christopher & Mendoza-Becerril, María A., 2025, First record of a hydrozoan (Cnidaria, Hydrozoa) growing on a sigalionid scaleworm (Annelida, Sigalionidae), Zootaxa 5570 (2), pp. 387-393 : 388-390

Bimeria vestita Wright, 1859

Figs. 1A–H

Material examined. LACM-AHF 1576 a, Panama, Gulf of Chiriquí, Secas Islands , 7°57’55’’N 82°00’3’’W, 45 m, R / V Velero III, Sta. 250-34, February 22, 1934, on the 5 th right anterior scale of Pelogenia fimbriata , the fertile colony was 1 mm above the dorsal line of the worm and extended to the lateral sides of the scale about 0.5 mm; proximally, over posterior scales and the dorsal midline, distally, right above the chaetae.

Description. Mature colony small (1.5 mm high), stolonal, monosiphonic, arising from creeping tubular stolons ( Figs. 1A–E ). Bilayered exoskeleton formed by perisarc and exosarc. Perisarc continuous from hydrorhiza to tentacle base unwrinkled at the base of hydrocaulus. Exosarc thin, thinner over hydranth, tentacle base, and hypostome, forming a pseudohydrotheca ( Figs. 1D, F, H ). Hydranth vasiform, merging with short pedicel. Hypostome conical, 10–12 tentacles in two very close whorls ( Fig. 1F ). Gonophore fixed sporosac on hydrorhiza, pedicellate, ovoid, without radial canals, enveloped in the thin exoskeleton ( Fig. 1E ). Nematocysts of tentacles: microbasic eurytele and desmoneme ( Fig. 1G ).

Distribution. Circumglobal in temperate and tropical waters ( Calder 2013). Records in the Eastern Pacific Ocean are restricted to Mexico and Panama ( Fraser 1938a, 1938b; Mendoza-Becerril et al. 2020).

Remarks. See Calder (1988) and Schuchert (2007) for taxonomic details and synonyms of this species. There are currently five species of the genus Bimeria (WoRMS 2024) . The species B. vestita is distinguished from the remainder of the genus species by the proximal part of its tentacles being ensheathed with an exoskeleton ( Calder 1988; Schuchert 2007).

Figures

FIGURE 1. Epibiosis of Bimeria vestita Wright, 1859 on Pelogenia fimbriata (Hartman, 1939) (LACM-AHF Poly 1576a). A.Anterior end of P. fimbriata, dorsal view, the asterisk indicates the prostomium, and the arrowhead indicates B. vestita attached to the scale. B. Hydroid colony on the surface of the scale still attached to the dorsum, side view. C. Anterior scale removed. D. Close-up of hydrants. E. Close-up of the colony, arrowhead indicates gonophore. F. Detail of tentacles. G. Nematocyst microbasic eurytele. H. SEM of a hydrant, arrowhead indicates pseudohydrotheca.