Clytia cf. noliformis ( McCrady, 1859 )

Calder, Dale R. & Faucci, Anuschka, 2021, Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands, Zootaxa 5085 (1), pp. 1-73 : 20-21

Clytia cf. noliformis ( McCrady, 1859)

Fig. 5f, g

Campanularia noliformis McCrady, 1859: 194 , pl. 11 fig. 4.

Type locality. Bermuda: Castle Harbour , on a dead octocoral (based on a neotype; Opinion 1986, International Commission on Zoological Nomenclature 2002) .

Voucher material. Pearl & Hermes Atoll, on Aglaophenia whiteleggei and adhering algae, 28.ix.2002, one colony, 2.8 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5419.—Laysan Island, on Halimeda sp. and Tridentata orthogonalis , 17.ix.2002, two colonies, to 3 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5420.

Remarks. These hydroids resemble Clytia noliformis ( McCrady, 1859) , and are provisionally assigned to that species here. Hydrothecae appear to be slightly longer, and embayments separating hydrothecal cusps somewhat deeper, than usual in C. noliformis (e.g., Nutting 1915; Calder 1991a, 2013). As such, they are essentially identical to specimens identified as C. noliformis from the tropical eastern Pacific by Calder et al. (2021). While hydroids from both locations also resemble Orthopyxis crenata ( Hartlaub, 1901) in hydrothecal outline, they differ from that species in having thinner hydrothecal walls, deeper cusps, and regularly annulated rather than sinuous pedicels. When present, gonosomes readily distinguish the two as well, with C. noliformis liberating a free medusa and O. crenata releasing a medusoid. However, our material was sterile.

Lindner & Migotto (2001) discovered an unusual category of nematocysts in C. noliformis , the merotrichous isorhiza. Nematocysts resembling them in shape and size were present in specimens examined here, but all were undischarged and their identity could not be determined with certainty.

Characters of both hydroid and medusa stages, as well as DNA barcoding (e.g., Maronna et al. 2016), support the inclusion of C. noliformis in the genus Clytia Lamouroux, 1812 . To date, no genetic comparisons have been undertaken of hydroids assigned to the species from the Atlantic and Pacific or Indian oceans. Past uncertainty over the specific identity of C. noliformis has been resolved by the designation of a neotype ( International Commission on Zoological Nomenclature 2002). The type locality of the species is Bermuda.

Clytia noliformis is a widely distributed species in warm waters of the Atlantic Ocean (e.g., Nutting 1915; Fraser 1944; Lindner & Migotto 2002; Calder 2013; Galea 2013; Gravili et al. 2015; Oliveira et al. 2016), and it is a major epibiont there on pelagic Sargassum ( Ryland 1974; Calder 1991a; 1995; Mendoza Becerril et al. 2020). The species has been recorded earlier in the Pacific from the coast of Ecuador ( Fraser 1948; Calder et al. 2021), from Guam ( Kirkendale & Calder 2003), the Korea Strait ( Lee et al. 2018, 18S rDNA sequences of plankton) and from Tahiti ( Pearman et al. 2020, metabarcoding of plankton). A record of it from Chile by Leloup (1974) was discounted by Galea and Schories (2012) as an unidentified species of Clytia . In the Indian Ocean, records of it exist from India ( Leloup 1932; Panikkar & Aiyar 1937; Mammen 1965; Sarma 1974, 1975; Pati et al. 2014, 2015), the Andaman and Nicobar Islands ( Leloup 1932; Deepa et al. 2015); Myanmar ( Leloup 1932), Madagascar ( Gravier 1970, Gravier-Bonnet 1999), La Réunion ( Bourmaud 2003) and Pakistan ( Moazzam & Moazzam 2006). Collections from the Northwestern Hawaiian Islands constitute the first records of C. noliformis , or of a species resembling it, in the central North Pacific Ocean.

Reported Distribution. Hawaiian archipelago. First record.

Elsewhere. Considered circumglobal in warm-temperate to tropical waters: western Pacific ( Kirkendale & Calder 2003); eastern Pacific ( Fraser 1948; Calder et al. 2021), western Atlantic ( Calder 2013; Oliveira et al. 2016); eastern Atlantic ( Faucci & Boero 2000); Indian Ocean ( Mammen 1965; Bourmaud 2003).

Figures

FIGURE 5. Clytiidae. a, Clytia brevithecata (Thornely, 1900), hydrotheca and pedicel, Nihoa, ROMIZ B5414. Scale equals 0.2 mm. b, Clytia elsaeoswaldae Stechow, 1914, hydrotheca and pedicel, Midway Atoll, ROMIZ B5415. Scale equals 0.1 mm. c, Clytia elsaeoswaldae Stechow, 1914, gonotheca, Midway Atoll, ROMIZ B5415. Scale equals 0.1 mm. d, Clytia linearis (Thornely, 1900), hydrotheca and distal end of pedicel, Gardner Pinnacles, ROMIZ B5418. Scale equals 0.2 mm. e, Clytia linearis (Thornely, 1900), gonotheca, Laysan Island, ROMIZ B5417. Scale equals 0.2 mm. f, Clytia cf. noliformis (McCrady, 1859), hydrotheca and pedicel, Pearl & HermesAtoll, ROMIZ B5419. Scale equals 0.2 mm. g, Clytia cf. noliformis (McCrady, 1859), hydrotheca and distal end of pedicel, Pearl & Hermes Atoll, ROMIZ B5419. Scale equals 0.1 mm.