Cirrholovenia tetranema Kramp, 1959

Calder, Dale R., Carlton, James T., Keith, Inti, Ashton, Gail V., Larson, Kristen, Ruiz, Gregory M., Herrera, Esteban & Golfin, Geiner, 2022, Biofouling hydroids (Cnidaria: Hydrozoa) from a Tropical Eastern Pacific island, with remarks on their biogeography, Journal of Natural History 56 (9 - 12), pp. 565-606 : 579-581

Cirrholovenia tetranema Kramp, 1959

( Figure 5b )

Cirrholovenia tetranema Kramp, 1959: 253 , fig. 17a, b [medusa].

Egmundella amirantensis Millard and Bouillon, 1973: 40 , fig. 5 [hydroid].

Type Locality: Solomon Islands: 9°25.416667° ʹ S, 160°E 29 m ( Kramp 1959) .

Material examined

Wafer Bay , 5.54535, −87.06185, 1 colony, on a hydroid stem, 0.25 mm high, without gonothecae, coll . G . Ashton, #240629.

Remarks

This hydroid has been widely reported across shallow tropical marine waters of the world, mostly as Lafoeina amirantensis ( Millard and Bouillon, 1973) . It was linked to the medusa Cirrholovenia tetranema Kramp, 1959 in life cycle studies by Migotto and Cabral (2005). Brinckmann (1965) had raised the polyp stage of the medusa even before the hydroid was described and named by Millard and Bouillon (1973). However, no nematothecae were observed on the hydrorhiza of her hydroids and she considered it to be referable to Cuspidella Hincks, 1866 . Moreira (1975) also undertook life cycle studies on the species by rearing planulae from known medusae, but did not attempt an identification of the polyp stage.

Cirrholovenia tetranema is a minute hydrozoan, with hydroids less than 0.5 mm high and medusae reaching 1.5 mm high and wide ( Kramp 1961, 1968). Originally described from medusae collected in the Tropical Western Pacific ( Solomon Islands, Strait of Malacca, Gulf of Thailand, the Philippines and Indonesia) ( Kramp 1959), both stages of the species have now been reported from warm waters of the Atlantic, Pacific and Indian oceans ( Migotto and Cabral 2005). In the Tropical Eastern Pacific, the hydroid has been reported from the Galápagos Islands and from the coast of mainland Ecuador ( Calder et al. 2003, as L. amirantensis ; 2019, 2021). Its range is extended here to Cocos Island, and it will likely be found elsewhere in the region. The medusa has yet to be reported from the Eastern Pacific.

In concert with its status in the Galapagos Islands ( Carlton et al. 2019), we treat C. tetranema as cryptogenic on Cocos Island.

Reported distribution

Cocos Island: first record.

Elsewhere: considered essentially circumglobal, in tropical and warm-temperate waters ( Migotto and Cabral 2005; Calder et al. 2019, 2021).

Figures

Figure 5. Leptothecata: Phialellidae, Cirrholovenia, Clytiidae. (a) Phialellidae (undetermined): three hydrothecae and pedicels, #240565. (b) Cirrholovenia tetranema: two hydrothecae and stolons, and a nematotheca, #240629. (c) Clytia brevithecata: hydrotheca and distal end of pedicel, #240600. (d) Clytia brevithecata: proximal end of pedicel and stolon, #240600. (e) Clytia linearis: hydrotheca and distal end of pedicel, #307693. (f) Clytia linearis: gonotheca, #307693. (g) Clytia obliqua: hydrotheca and distal end of pedicel, #240629.(h) Clytia obliqua: hydrotheca and distal end of pedicel,#253541. (i) Clytia obliqua: gonotheca, #253541. (j) Clytia obliqua: gonotheca, #240629. Scale bars: a, c–j = 0.1 mm; b = 0.05 mm.