Sertularella unituba Calder, 1990

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141 : 90-91

Sertularella unituba Calder, 1990 [1991a]

Fig. 21j

Sertularella conica .— Van Gemerden-Hoogeveen, 1965: 32, fig. 7.—Leloup 1935: 44 [not Sertularella conica Allman, 1877 ]. Sertularella gayi unituba Calder, 1990 [1991a]: 103, figs. 54a, b.

Type locality. Bermuda: 2 km SE of Castle Roads , 50-80 m (Calder 1990 [1991a]: 103, as Sertularella gayi unituba ) .

Material examined. Southwest Florida Shelf, middle shelf west of Gasparilla Island, 26°45.86’N, 83°21.44’W, 50 m, 18 July 1981, triangle dredge, one colony, 5.5 cm high, without gonophores, coll. Continental Shelf Associates, ROMIZ B2001.

Remarks. This hydroid was originally described from Bermuda as a subspecies of Sertularella gayi ( Lamouroux, 1821) . Medel & Vervoort (1998) examined material of S. gayi unituba Calder, 1990 [1991a], including the holotype, and elevated the subspecific name to specific rank. Corroborating this change, Moura et al. (2011) found that a hydroid consistent with the phenotype of S. unituba from the Azores was indeed close to S. gayi , but genetically distinct from it. As for S. gayi , difficulties exist in identification of the species even within its main center of distribution in northwestern Europe ( Cornelius 1995b: 72). Characters distinguishing S. unituba from S. gayi and S. gayi robusta Allman, 1874a were reviewed by Medel & Vervoort (1998: 54). The trinomen S. gayi robusta had been used earlier by Allman (1873), as “ Sertularella gayii … variety robusta ”, but as a nomen nudum.

Hydroids identified as S. gayi have been reported from the Caribbean Sea and Gulf of Mexico a number of times (see Nutting 1904; Fraser 1944; Deevey 1950; Vervoort 1968). Given the incertitude surrounding identification of the species noted above, confirmation is needed that S. gayi actually exists in the warm western Atlantic. While it is likely that some records of the species were based on S. unituba , existing descriptions and illustrations of them are insufficient to establish which ones. However, it is much more certain that hydroids assigned to S. conica Allman, 1877 by Leloup (1935) and Van Gemerden-Hoogeveen (1965) were misidentified specimens of S. unituba . Although Leloup did not describe or illustrate his specimens, the same material was examined later by Van Gemerden- Hoogeveen. Her description and illustrations of the species conform to S. unituba , not S. conica .

Regarded as synonyms of S. unituba by Medel & Vervoort (1998) were two older names, Sertularia exigua Allman, 1888 and S. laxa Allman, 1888 , applied to hydroids from bathyal waters in the Azores. However, both names are invalid as junior primary homonyms. Shortly before publication, Allman (1888) recognized that his Sertularia exigua was predated by Sertularia exigua Allman, 1877 , and he proposed S. laxa as a replacement name for it in the same work. However, that binomen is also predated, by S. laxa Lamarck, 1816 . Sertularella unituba thus stands the valid name of the species. I cannot agree with Galea (2013: 24) that S. unituba and S. conica are conspecific.

In addition to the original description of S. unituba , the species has been described and discussed at length by Medel & Vervoort (1998) from material collected in the Cape Verde Islands. Besides inspecting the holotype of the species, syntypes of Sertularia exigua (and its replacement name S. laxa ) from the Azores were examined by them as well. New material of S. unituba from the Cape Verde region was studied and discussed by Vervoort (2006).

Sertularia unituba has most often been collected at intermediate depths. In the western North Atlantic, it has been reported over a bathymetric range of 24–274 m (Leloup 1935, as Sertularella conica ; Van Gemerden-Hoogeveen 1965: 32, as Sertularella conica ; Calder 1990 [1991a], as Sertularella gayi unituba ; Medel & Vervoort 1998; Calder 2013). Records from the eastern North Atlantic extend from 61–1200 m, although most specimens were collected at depths between 61–250 m ( Medel & Vervoort 1998; Vervoort 2006). Allman’s (1888) specimens of S. exigua / S. laxa from the Challenger Expedition came from a depth of 450 ftm (823 m) off the Azores.

Reported distribution. Gulf coast of Florida. Dry Tortugas, 25–45 ftm (46–82 m) (Leloup 1935: 44, as Sertularella conica ).—Dry Tortugas, 25 ftm (46 m) ( Van Gemerden-Hoogeveen 1965: 32, as Sertularella conica ).

Elsewhere in western North Atlantic. Bermuda: 2 km SE of Castle Roads , 50–80 m, on calcareous rubble (Calder 1990 [1991a]: 103, as Sertularella gayi unituba ; Medel & Vervoort 1998: 58) .— Bermuda: 2 km S of “Castle Rock” ( Castle Roads ), on a crab pot line, 274 m ( Medel & Vervoort 1998: 60) .— Bermuda: Argus (= Plantagenet)

Bank ( Calder 2000: 1134, as Sertularella gayi ).— USA: Florida, off St. Lucie Inlet , 27°11.6’N, 80°00.7’W, 41 m + off Vero Beach, Bethel Shoal, 27°42.6’N, 80°06.8’W, 24 m ( Calder 2013: 30) .

Figures

FIGURE 21. a, Amphisbetia distans: part of hydrocaulus with two hydrothecal pairs, Sanibel Island, ROMIZ B4387. Scale equals 0.1 mm. b, Amphisbetia distans: gonotheca, Sanibel Island, ROMIZ B4386. Scale equals 0.1 mm. c, Dynamena disticha: part of hydrocaulus with two hydrothecal pairs, Sanibel Island, ROMIZ B4410. Scale equals 0.1 mm. d, Dynamena pourtalesi: part of hydrocaulus with two hydrothecal pairs, Southwest Florida Shelf, ROMIZ B306. Scale equals 0.2 mm. e, Idiellana pristis: base of hydrocaulus with a branch, Sanibel Island, ROMIZ B4390. Scale equals 0.2 mm. f, Idiellana pristis: part of branch with hydrothecae, Sanibel Island, ROMIZ B4390. Scale equals 0.1 mm. g, Tridentata turbinata: part of hydrocaulus with two hydrothecal pairs, Sanibel Island, ROMIZ B4393. Scale equals 0.2 mm. h, Sertularella areyi: part of colony with two hydrothecae, Southwest Florida Shelf, ROMIZ B1978. Scale equals 0.2 mm. i, Sertularella diaphana: part of colony with three hydrothecae, Southwest Florida Shelf, ROMIZ B4392. Scale equals 0.2 mm. j, Sertularella unituba: part of colony with two hydrothecae, Southwest Florida Shelf, ROMIZ B2001. Scale equals 0.2 mm.