Thyroscyphus marginatus ( Allman, 1877 )

Gil, Marta & Ramil, Fran, 2025, Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau, Zootaxa 5577 (1), pp. 1-89 : 44-45

Thyroscyphus marginatus ( Allman, 1877)

Obelia marginata Allman, 1877: 9–10 , pl. 6 figs 1–2. Thyroscyphus marginatus : Calder, 1991: 79–81, fig. 41–42.— Calder, 2013: 23–24, fig. 7C–D.

Cnidoscyphus marginatus : Buchanan, 1957: 364, fig. 13.— Vervoort, 1959: 248–250, fig. 20.— Medel & Vervoort, 1998: 11.

Material examined. BISSAU-0810, stn BS191, 10º18'25"– 10º19'20"N, 16º08'47"– 16º08'47"W, 24–25 m, 3-XI-2008: nine colonies without gonothecae, up to 78 mm high, of which one colony growing on a worm tube.

BISSAU-0810, stn BS192, 10º19'30"– 10º20'15"N, 16º10'27"– 16º10'59"W, 24 m, 3-XI-2008: two colonies, up to 127 mm high without gonothecae, substrate unknown.

BISSAU-0810, stn BS194, 10º21'59"– 10º22'36"N,16º13'23"– 16º14'03"W, 21–24 m, 3-XI-2008: seven colonies, 22–130 mm high without gonothecae, substrate unknwon.

BISSAU-0810, stn BS195, 10º22'44"– 10º23'22"N, 16º15'37"– 16º16'18"W, 29 m, 3-XI-2008: eight colonies, 28–362 mm high without gonothecae, substrate unknown.

Remarks. Our material conforms to that described by Vervoort (1959, as C. marginatus ). We found very large colonies (up to 362 mm in height), which are larger than those described by Calder (2013) and Allman (1877).

Our finding represents also the first record of T. marginatus for Guinea-Bissau.

Biology. This species has been found growing on worm tubes ( Vervoort 1959), rocks ( Calder 1991), calcareous algae and barnacles ( Medel & Vervoort 1998). In the northern hemisphere, gonothecae have been found in June ( Medel & Vervoort 1998), July and August ( Calder 1991).

In our material, one colony was found growing on a worm tube. Gonothecae were not observed.

Distribution. Thyroscyphus marginatus is an amphi-Atlantic species ( Calder 2013). In West Africa, it has been recorded from the Cape Verde Islands ( Medel & Vervoort 1998), the Republic of Guinea, Sierra Leone ( Vervoort 1959, as Cnidoscyphus marginatus ) and Ghana ( Buchanan 1957; Vervoort 1959; both as C. marginatus ). Its bathymetric distribution ranges from 0 ( Medel & Vervoort 1998) to 90 m ( Calder 1991).

Our colonies were collected at depths between 21–29 m.