Sertularella angulosa Bale, 1894

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 : 26-27

Sertularella angulosa Bale, 1894

Fig. 7f–h

Sertularella angulosa Bale, 1894: 102 , pl. 4 fig. 6.

Type locality. Unknown , but likely Australia ( Bale 1894) .

Voucher material. Kure Atoll, on algae and a bryozoan, 26.ix.2002, two colonies, to 5 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5425.—French Frigate Shoals, on hydroid stem, 12.ix.2002, one colony, 7 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5477.

Remarks. These small hydroid colonies appear closest in morphology to accounts of Sertularella angulosa Bale, 1894 from Indonesia by Billard (1925b) and Vervoort & Vasseur (1977), the latter in a discussion of S. robusta Coughtrey, 1876 from Moorea, French Polynesia. Indeed, the two have generally been considered conspecific ( Hodgson 1950; Vervoort & Vasseur 1977; Hirohito 1995; Vervoort & Watson 2003). However, specimens examined here have been excluded from S. robusta , the putative senior synonym, largely on zoogeographic grounds. Originally described from Foveaux Strait at the southern tip of New Zealand ( Coughtrey 1876), and with a centre of distribution in cold waters elsewhere in the Southern Hemisphere ( Leloup 1960, 1974; Blanco 1968; Vervoort 1972; Vervoort & Watson 2003; Galea 2007; Galea et al. 2009; El Beshbeeshy 2011; Galea & Schories 2012; Oliveira et al. 2016; Galea et al. 2017), it seems improbable that S. robusta extends into tropical and warm-temperate parts of the Pacific and Indian oceans. Hydroids assigned to it from such areas ( Pennycuik 1959; Vervoort & Vasseur 1977; Hirohito 1983, 1995; Gravier-Bonnet & Bourmaud 2012) are likely to have been misidentified. Thus, S. angulosa has been taken here to be valid, and populations inhabiting lower latitudes in the Pacific, including Kure Atoll, are more likely referable to it than to S. robusta . In addition to the original account of S. angulosa by Bale (1894), thorough accounts of its trophosome and gonosome have been given by Billard (1925b) and by Vervoort & Vasseur (1977, partly under the binomen S. robusta ). Uncertainties nevertheless remain over the identity of the species. Bale’s (1894) type material of S. angulosa was sterile, and while his collections were almost certainly from Australia, the exact type locality and original habitat of the species are unknown.

Also included in the synonymy of S. robusta by Vervoort & Vasseur (1977) was S. microgona von Lendenfeld, 1885 . From accounts of it by Billard (1925b) and Vervoort & Vasseur (1977, as S. robusta , in part), the species differs from S. angulosa in having hydrothecae that are more slender and more tapered towards the distal end. Vervoort & Vasseur also compared the type of S. inconstans Billard, 1925b with their S. robusta . Differences between them were said to include the larger colony size, smaller submarginal cusps, and remarkably thick stem perisarc of S. inconstans . Finally, hydrothecae of the similar S. keiensis Billard, 1925b are slenderer at the distal end, and four submarginal cusps are present ( Billard 1925b; Hirohito 1995; Xu et al. 2014b) rather than three, as in S. microgona , S. angulosa , and S. robusta .

As for S. robusta Coughtrey, 1876 , its binomen is a permanently invalid junior primary homonym of S. gayi var. robusta Allman, 1874a (ICZN 1999, Art. 57.2), originally described from the Faroe-Shetland Trough in the North Atlantic Ocean. It is nomenclaturally inconsequential that Allman’s name was introduced as a variety (ICZN 1999, Art. 45.6.4). Moreover, Reversal of Precedence provisions cannot be applied (ICZN 1999, Art. 23.9.1.1) to validate the junior homonym as a nomen protectum because its senior homonym has been used as a valid name after 1899, including in certain recent works (e.g., Nutting 1904: 79; Billard 1906a: 331; 1906b: 185; Bedot 1925: 370; Vervoort 1972: 118; Ramil & Vervoort 1992: 223; Calder & Vervoort 1998: 39, with a synonymy list; Henry et al. 2008: 794; Gil & Ramil 2017: 428). The junior homonym S. robusta Coughtrey, 1876 is replaced here by the binomen S. quasiplana Trebilcock, 1928 , originally described as S. robusta var. quasiplana Trebilcock, 1928 . The name of that variety qualifies as a replacement (ICZN 1999, Art. 60.2) in being considered a synonym of S. robusta by Vervoort & Watson (2003). As with the S. robusta of Coughtrey, it was originally described from New Zealand (Island Bay). Also described as a variety of the same species by Trebilcock (1928) was S. robusta var. flucticulata . Although sharing the same general type locality (Bluff, in Foveaux Strait, New Zealand) with S. robusta , it was excluded from consideration as a replacement name because it has been included in the synonymy of S. integra Allman, 1876 ( Vervoort & Watson 2003). With respect to authorship and date of the Atlantic species, now regarded in some works as distinct from S. gayi ( Lamouroux, 1821) ( Moura et al. 2011) , it should be credited to Allman (1874a) and not Coughtrey (1876).

The name Sertularella polyzonias var. robusta as utilized by Verrill (1873a:10) was not accompanied by a description, illustration, or indication, and is a nomen nudum. The trinomen S. polyzonias f. robusta appeared again in Kirchenpauer (1884) for hydroids “…mit viel dickeren Stämmen und Zweigen und grösseren Hydrotheken…” from the Cape of Good Hope, South Africa. That hydroid was briefly mentioned in the work of Hartlaub (1901), and an illustration of it was provided, but its nomenclature was left unsettled. The name S. polyzonias var. robusta was listed by Bedot (1916, 1918, 1925), but in reference to the hydroid of Verrill (1873a), not Kirchenpauer (1884). The nomenclature of Kirchenpauer’s junior homonym was finally settled by Millard (1964). She recognized it as distinct from S. polyzonias ( Linnaeus, 1758) , and linked it instead to S. megista Stechow, 1923b . Finally, another junior homonym of both S. gayi var. robusta Allman, 1874a and S. robusta Coughtrey, 1876 is S. robusta Clark, 1877 . That binomen has been replaced by the name S. albida Kirchenpauer, 1884 .

Material assigned to S. angulosa by Billard (1925b) was collected at depths between 59 m and 90 m at several locations in Indonesia. Billard believed that hydroids identified by Jäderholm (1905) as S. tenella ( Alder, 1856) , from Tierra del Fuego, were conspecific. Given the cold Southern Hemisphere collection locale of Jäderholm’s material, however, it is more likely referable to S. robusta (= S. quasiplana ), as indicated by Galea et al. (2017).

Vervoort & Vasseur (1977) found S. angulosa (as S. robusta ) to be the most common hydroid on the entire Tiahura barrier reef at Moorea. It extended from the reef flat, at 1 m, to the spur and groove zone at 20 m, and reached peak abundance in cavities on the reef flat.

Reported Distribution. Hawaiian archipelago. First record.

Elsewhere. Indian Ocean ( Millard & Bouillon 1973, as Sertularella robusta ; Gravier-Bonnet & Bourmaud 2012, as S. robusta ), western Pacific Ocean ( Pennycuik 1959, as S. robusta ; Vervoort & Vasseur 1977, as S. robusta ; Hirohito 1983, 1995, as S. robusta ).

Figures

FIGURE 7. Sertularellidae. a, Sertularella affinicostata, sp. nov., holotype, hydrocaulus with two hydrothecae, Darwin Island, Galapagos Islands, Ecuador, ROMIZ B3339. Scale equals 0.1 mm. b, Sertularella affinicostata, sp. nov., holotype, hydrocaulus with male gonotheca and a hydrotheca, Darwin Island, Galapagos Islands, Ecuador, ROMIZ B3339. Scale equals 0.1 mm. c, Sertularella affinicostata, sp. nov., paratype, hydrocaulus with three hydrothecae, French Frigate Shoals, ROMIZ B5486. Scale equals 0.1 mm. d, Sertularella affinicostata, sp. nov., paratype, hydrocaulus with two hydrothecae, French Frigate Shoals, ROMIZ B5486. Scale equals 0.1 mm. e, Sertularella affinicostata, sp. nov., paratype, hydrocaulus with a single hydrotheca, French Frigate Shoals, ROMIZ B5486. Scale equals 0.1 mm. f, Sertularella angulosa Bale, 1894, part of hydrocaulus with four hydrothecae, French Frigate Shoals, ROMIZ B5477. Scale equals 0.2 mm. g, Sertularella angulosa Bale, 1894, part of hydrocaulus with four hydrothecae, Kure Atoll, ROMIZ B5425. Scale equals 0.1 mm. h, Sertularella angulosa Bale, 1894, part of hydrocaulus with two hydrothecae, Kure Atoll, ROMIZ B5425. Scale equals 0.1 mm. i, Sertularella areyi Nutting, 1904, part of hydrocaulus with three hydrothecae, Nihoa, ROMIZ B5478. Scale equals 0.2 mm.