Halopteris clarkei ( Nutting, 1900 )

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141 : 103-104

Halopteris clarkei ( Nutting, 1900)

Fig. 23 d–f

Plumularia gracilis Clarke, 1879: 246 , pl. 5, figs. 29, 30, 30b, c [junior primary homonym of Plumularia gracilis Murray,

1860]. Plumularia clarkei Nutting, 1900: 61 , pl. 3, fig. 5 [nomen novum for Plumularia gracilis Clarke, 1879 ]. Antennella diaphana diaphana .— Van Gemerden-Hoogeveen, 1965: 49, figs. 23–28 [part; not Antennella diaphana ( Heller,

1868) (= Halopteris diaphana )]. Halopteris gracilis .— Schuchert, 1997: 110, figs. 39a–d (right), e, g.

Type locality. Cuba: off Havana, 175 ftm (320 m) ( Clarke 1879: 247, as Plumularia gracilis ) .

Material examined. Southwest Florida Shelf, middle shelf west of North Naples, 26°16’30”N, 83°42’30”W, 80.5 m, 03 November 1980, one colony fragment, 2.6 cm high, with one male gonotheca, coll. Continental Shelf Associates, ROMIZ B2097.— Southwest Florida Shelf, middle shelf west of North Naples , 26°16.83’N, 83°23.81’W, 59.5 m, 19 July 1981, triangle dredge, two colony fragments, up to 3.1 cm high, without gonophores, coll. Continental Shelf Associates, ROMIZ B2096 .

Remarks. Plumularia gracilis , the name initially applied to this species by Clarke (1879), is an invalid junior primary homonym of Plumularia gracilis Murray, 1860 . Nutting (1900) recognized the homonymy and proposed P. clarkei as a replacement name for it. Following current usage, the species is assigned here to the genus Halopteris Allman, 1877 . However, revision of Halopteris is warranted and it is unlikely that H. clarkei will prove to be congeneric with H. carinata Allman, 1877 , the type species of the genus.

Halopteris clarkei falls within a group of species currently assigned to Halopteris that have hydrocladia arranged in opposite pairs ( Schuchert 1997). Others in the group include H. catharina ( Johnston, 1833) and H. geminata ( Allman, 1877) from the Atlantic Ocean, H. plagiocampa ( Pictet, 1893) from the western Pacific, H. opposita ( Mulder & Trebilcock, 1911) and H. zygocladia ( Bale, 1914) from Australia, and H. gemellipara Millard, 1962 from South Africa. Halopteris enersis Galea, 2006 from Chile has subsequently been added to this group. Characters used to differentiate these species have been outlined by Schuchert (1997) and Galea (2006).

The hydroid of H. clarkei is much like H. geminata , originally described from a site off Sand Key in the Straits of Florida. Nutting (1900: 61) pondered whether H. clarkei and H. geminata , along with H. catharina , might prove conspecific, but in the end recognized all three as valid. Fraser (1944: 347) saw little justification for combining them. Schuchert (1997: 115) suspected that H. clarkei (as H. gracilis ) and H. geminata might be conspecific, but recognized both given the need for more evidence that they were identical. He considered them distinct from H. catharina , a species differing in having two pairs of lateral nematothecae instead of a single pair and in lacking axillar nematothecae ( Schuchert 1997: 113). Hydrothecae of H. clarkei also usually overtop the transverse node of the hydrocladial internodes ( Fraser 1946 [ 1947 a]: 366–367), whereas those of H. catharina do not quite reach the node ( Cornelius 1995b, figs. 29B–D; Schuchert 1997, figs. 38b, c). Hydroids of H. clarkei appear to differ from those of H. geminata in having (1) an unbranched rather than a dichotomously branched hydrocaulus, (2) one rather than two or three nematothecae on athecate hydrocladial internodes, and (3) lateral nematothecae with bulbous rather than straight walls ( Schuchert 1997: 114). As with H. clarkei , H. geminata is poorly known and infrequently observed, although it was recently identified in several collections from slope waters off the southeastern United States by Henry et al. (2008).

Schuchert (1997) discovered that some of the material from the Dry Tortugas identified as Antennella diaphana diaphana by Van Gemerden-Hoogeveen (1965) was referable instead to H. gracilis (= H. clarkei ). Records of the species from near St. Lucie Inlet, on the Atlantic coast of Florida, by Schuchert (1997) and Calder (2013) are based on the same collection (ROMIZ B1096).

Halopteris clarkei has been reported only from shelf and upper slope waters of the western North Atlantic between North Carolina ( Wells et al. 1964, as Plumularia clarkei ) and Cuba ( Schuchert 1997, as Halopteris gracilis ). Further details on the species are given by Schuchert (1997, as H. gracilis ) and Calder (2013).

Reported distribution. Gulf coast of Florida. Dry Tortugas, 46–49 m ( Van Gemerden-Hoogeveen 1965: 49, as Antennella diaphana diaphana (part); Schuchert 1997: 111, as Halopteris gracilis ).

Elsewhere in western North Atlantic. Cuba: off Havana, 175 ftm (320 m) ( Clarke 1879: 247, as Plumularia gracilis ; Nutting 1900: 61, as Plumularia clarkei ).— Cuba: off Havana, 23°11’45”N, 82°17’54”W, 182 ftm (333 m) ( Nutting 1900: 61, as Plumularia clarkei ).— USA: North Carolina, Core Banks, on Aequipecten gibbus , 17–20 ftm (31–37 m) ( Wells et al. 1964: 566, as Plumularia clarkei ).— USA: South Carolina, inner (17–18 m) and outer (46–69 m) continental shelf + Georgia, inner (17–22 m) and outer (59–67 m) continental shelf ( Wenner et al. 1984: 21, 40).— Cuba: off Havana ( Schuchert 1997: 110, as Halopteris gracilis ).— USA: Florida, off St. Lucie Inlet, 27°11.8’N, 79°57.3’W, 87 m ( Schuchert 1997: 110, as Halopteris gracilis ; Calder 2013: 43).

Figures

FIGURE 23. a, Halopteris alternata: part of a hydrocaulus with proximal end of a hydrocladium, Fort Myers Beach, ROMIZ B4400. Scale equals 0.1 mm. b, Halopteris alternata: part of a hydrocladium with two hydrothecae, Fort Myers Beach, ROMIZ B4400. Scale equals 0.1 mm. c, Halopteris alternata: part of hydrocaulus of an “Antennella form” with a developing hydrocladium, Fort Myers Beach, ROMIZ B4400. Scale equals 0.1 mm. d, Halopteris clarkei: part of hydrocaulus with proximal ends of two hydrocladia, Southwest Florida Shelf, ROMIZ B2097. Scale equals 0.1 mm. e, Halopteris clarkei: hydrocladial hydrotheca and nematothecae, Southwest Florida Shelf, ROMIZ B2097. Scale equals 0.1 mm. f, Halopteris clarkei: male gonotheca with a nematotheca, Southwest Florida Shelf, ROMIZ B2097. Scale equals 0.05 mm. g, Monostaechas quadridens: part of colony with a hydrotheca and nematothecae, Southwest Florida Shelf, ROMIZ B2100. Scale equals 0.1 mm. h, Ventromma halecioides: part of hydrocaulus with a hydrocladium, Sanibel Island, ROMIZ B4395. Scale equals 0.2 mm. i, Ventromma halecioides: part of hydrocaulus with proximal end of a hydrocladium, Sanibel Island, ROMIZ B4395. Scale equals 0.1 mm.