Nemalecium lighti ( Hargitt, 1924 )

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 : 22-23

Nemalecium lighti ( Hargitt, 1924)

Fig. 6c , pl. 4, fig. 13

Halecium lighti Hargitt, 1924: 489 , pl. 4 fig. 13.

Halecium ( beani ?).— De Oreo, 1946: 645, figs 7–9 [not Halecium beanii ( Johnston, 1838) ].

Halecium beani .— Chu & Cutress, 1954: 9 [not Halecium beanii ( Johnston, 1838) ].

? Halecium beani .— Cooke, 1977: 87, fig. 15.— Coles et al., 1999a: 120, 194, 209 [not Halecium beanii ( Johnston, 1838) ]. Halecium sp. — Coles et al., 2002a: 206, 318; 2004: 73; 2009: 59, 76.

Halecium beanii .— Carlton & Eldredge, 2009: 35 [not Halecium beanii ( Johnston, 1838) ].

Nemalecium lighti . — Calder, 2010: 53; 2020: 214, fig. 4g, h.

Type locality. Philippines: Oriental Mindoro, Puerto Galera ( Hargitt 1924, as Halecium lighti ) .

Voucher material. Kure Atoll, on algae and detached, 25.ix.2002, three colonies or colony fragments, to 1.6 cm high, without gonothecae, coll. A. Faucci, ROMIZ B5424.

Remarks. Nemalecium Bouillon, 1986 is a remarkable genus of hydroids. Its species are readily distinguished by having 1–2 curved, finger-like nematodactyls ( Bouillon 1986) in addition to typical tentacles in the tentacular whorl of the hydranth. Immense pseudostenotele nematocysts (>25 µm long) are borne on these nematodactyls. To date, two species, N. lighti ( Hargitt, 1924) and N. gracile Galea, Ferry & Bertot, 2012 , have been described and assigned the genus. Of these, only N. lighti has been reported to date from the Pacific and Indian oceans, although undescribed species are believed to occur there ( Gravier-Bonnet & Migotto 2000; Gravier-Bonnet & Bourmaud 2006, 2012; Di Camillo et al. 2008; Galea et al. 2012; Boissin et al. 2018). Records of N. gracile to date are restricted to the Atlantic Ocean, while N. lighti is taken to be circumglobal in shallow, warm waters. In Hawaii, the species is well-represented in nearshore habitats ( Calder 2020). It was misidentified in early records from the islands as Halecium beanii ( Johnston, 1838) , a species inhabiting cool to cold rather than tropical waters ( Fraser 1947; Cornelius 1995a, Schuchert 2005; Antsulevich 2015). Moreover, those first Hawaiian reports were of a species that was venomous ( De Oreo 1946; Chu & Cutress 1954). Nemalecium lighti is known to sting humans ( Marques et al. 2002; Santhanam 2020), while H. beanii is likely innocuous.

Taxonomically, Maronna et al. (2016) disputed the inclusion of Nemalecium in Haleciidae Hincks, 1869 based on molecular data, referring it instead to the order Plumupheniida Maronna et al., 2016 . Until its family-group affinities are resolved, however, we continue to assign it to Haleciidae Hincks, 1869 given its haleciid-like morphological characters.

Recent reviews of N. lighti have been given elsewhere (Calder 2019; Calder et al. 2019).

Reported Distribution. Hawaiian archipelago. Oahu: near Honolulu, human envenomations ( De Oreo 1946, as Halecium ( beani ?)); Maunalua Bay, on rubble ( Cooke 1977, as H. beani ); Barbers Point Harbor, barge pier (Coles et al. 1999, as Halecium sp. ); Honolulu Harbor, wood block, coll. 1945, Bishop Museum, BPBM-D-260 (Coles et al. 1999, as Halecium sp. ; Carlton & Eldredge 2009, as H. beanii ); Kaneohe Bay, coll. 1963, Bishop Museum, BPBMD-349 ( Coles et al. 2002a, as Halecium sp. ); Kaneohe Bay, Sag Harbor ( Coles et al. 2002a, as Halecium sp. ); Pearl Harbor, entrance channel ( Coles et al. 2009, as Halecium sp. ); Pearl Harbor, West Loch entrance channel ( Coles et al. 2009, as Halecium sp. ); Pearl Harbor, Hospital Point south ( Coles et al. 2009, as Halecium sp. ); Pearl Harbor, Utah Memorial ( Coles et al. 2009, as Halecium sp. ); Pearl Harbor, Hawaiian Electric Company discharge ( Coles et al. 2009, as Halecium sp. ); Honolulu Harbor, Piers 40–41 ( Coles et al. 2009, as Halecium sp. ); Keehi Lagoon, marina docks ( Coles et al. 2009, as Halecium sp. ); Keehi Lagoon, barge wreck ( Coles et al. 2009, as Halecium sp. ); Keehi Lagoon, stream mouth ( Coles et al. 2009, as Halecium sp. ); north shore, in alphaeid crevices on corals ( Calder 2010).—Hawaiian Islands: no specific location ( Chu & Cutress 1954, as H. beani ).—Kauai: Nawiliwili Harbor ( Coles et al. 2004, as Halecium sp. ).—Molokai: Kaunakakai main dock ( Coles et al. 2004, as Halecium sp. ).—Maui: Kahului Harbor Pier 1 ( Coles et al. 2004, as Halecium sp. ).

Elsewhere. Atlantic, Pacific, and Indian oceans; warm waters ( Calder et al. 2019).

Figures

FIGURE 6. Haleciidae. a, Halecium sp., part of colony with two hydrothecae, Pearl & Hermes Atoll, ROMIZ B5421. Scale equals 0.1 mm. b, Halecium sp., part of colony with five hydrothecae, Pearl & Hermes Atoll, ROMIZ B5421. Scale equals 0.1 mm. c, Nemalecium lighti (Hargitt, 1924), part of hydrocaulus, with four hydrothecae, Kure Atoll, ROMIZ B5424. Scale equals 0.1 mm.