Acryptolaria longitheca

Acryptolaria longitheca (Allman, 1877)

Figs. 6a, b, 7a

Cryptolaria longitheca Allman, 1877: 19, pl. 13, figs. 4–5.— Clarke, 1879: 244, pl. 2, figs. 7–10.

Acryptolaria longitheca. — Fraser 1943: 90.

Type locality. Bahamas: Cay Sal Bank, Double-Headed Shot Key, 315 ftm (576 m) (Allman 1877: 19, as Cryptolaria longitheca).

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, three colony fragments, up to 7 cm high, without gonophores, coll. Continental Shelf Associates, ROMIZ B1907.— Southwest Florida Shelf, middle shelf west of North Naples, 26°16.72′N, 83°46.82′W, 83 m, 24 July 1981, otter trawl, one colony, 8.3 cm high, without gonophores, coll. Continental Shelf Associates, ROMIZ B1905.— Southwest Florida Shelf, outer shelf west of North Naples, 26°16.67′N, 84°04.08′W, 137 m, 25 July 1981, triangle dredge, five colony fragments, up to 9.3 cm high, some with coppiniae, coll. Continental Shelf Associates, ROMIZ B1902.

Remarks. Allman’s (1877) original description of Acryptolaria longitheca (as Cryptolaria longitheca) was brief and in some respects inaccurate. In particular, hydrothecae were said to be “…cylindrical throughout, presenting no diminution of their diameter towards the base…” That characterization was followed by Fraser (1943, 1944) in his accounts of the species. However, Clarke (1879: 244) found that hydrothecae in Allman’s type indeed tapered towards the base. His observation was confirmed by Peña Cantero et al. (2007), who examined, illustrated, and redescribed the holotype colony. A combination of hydrothecal characters was used by them to distinguish the species from others of the genus Acryptolaria Norman, 1875: (1) abcauline wall homogeneously curved; (2) diameter of hydrothecal cavity distinctly wider in free part than in adnate part; (3) hydrothecal base gradually tapered rather than abruptly bottlenecked; (4) hydrothecal aperture diameter <300 μm rather than>300 μm; (5) adcauline wall adnate for half rather than 2/3 of its length; (6) free part of adcauline wall nearly straight (Peña Cantero et al. 2007: 273). Material examined here from the Southwest Florida Shelf conformed with all of these characters. The species has been taken to be valid in major recent works on Acryptolaria by Peña Cantero et al. (2007) and Peña Cantero & Vervoort (2010).

In addition to hydrothecal characters, the cnidome was also found by Peña Cantero et al. (2007) to be useful in distinguishing species of Acryptolaria. Large nematocysts in material examined here (Fig. 7a) appeared to be macrobasic mastigophores (19.4–23.0 μm long x 5.9–6.5 μm wide, undischarged, n=10, ROMIZ B1902). These were somewhat more slender than ones described in type material of A. longitheca (21–23 μm long × 6.5–8 μm wide) by Peña Cantero et al. (2007) and Peña Cantero & Vervoort (2010), but the difference was small and considered taxonomically inconsequential.

Gonothecae in material identified as A. longitheca by Clarke (1879) from the western edge of the Southwest Florida Shelf (25°33’N, 84°21’W), and considered correctly identified by Peña Cantero et al. (2007) and Peña Cantero & Vervoort (2010), also correspond in morphology with those examined here (Fig. 6b). Clarke described them as “…polygonal in form, largest at the distal end, tapering to the base, crowded so closely together that the walls of adjoining bodies are in contact throughout their length, and are provided with a small tubular orifice arising from the centre of the distal end…” Gonothecae of specimens identified as A. longitheca by Calder & Vervoort (1998) from the Mid-Atlantic Ridge differ in being much more slender, and that deep water material may be referable to a different species.

Distribution records of this species were listed by Peña Cantero et al. (2007: 289). Most of them were considered questionable, and with justification. Considered valid, in addition to Allman’s (1877) account from the Bahamas, was that of Clarke (1879) from the Southwest Florida Shelf. Material examined here came from the same general locality. Elsewhere, Peña Cantero & Vervoort (2010) reported Acryptolaria longitheca from the western Pacific Ocean (Loyalty Islands and Norfolk Ridge). If only on zoogeographic grounds, those records need confirmation. Said by them to be similar to A. longitheca is A. gemini Peña Cantero & Vervoort, 2010 from Gemini Seamount, Vanuatu.

Reported distribution. Gulf coast of Florida. Southwest Florida Shelf, NW of the Dry Tortugas, 25°33′N, 84°21′W, 101 ftm (185 m) (Clarke 1879: 244, as Cryptolaria longitheca).—?S of Florida Keys, 24°18’N, 80°58’30”W, 324 ftm (593 m) (Fraser 1943: 90).

Elsewhere in western North Atlantic. Bahamas: Cay Sal Bank, Double-Headed Shot Key, 315 ftm (576 m) (Allman 1877: 19, as Cryptolaria longitheca).—? Dominica: 76 ftm (139 m) (Fewkes 1881a: 128, as Cryptolaria longitheca).—? French Lesser Antilles: Martinique, 334 ftm (611 m) (Fewkes 1881a: 128, as Cryptolaria longitheca).—? Barbados: 103 ftm (188 m) (Fewkes 1881a: 128, as Cryptolaria longitheca).— Barbados: 13°11’54”N, 59°38’45”W, 73 ftm (134 m) (Fraser 1943: 90).—? North Atlantic Ocean: abyss E of South Carolina, USA, 32°34’N, 74°21.5’W, 4681 m (Vervoort 1972: 45).—? Bermuda: Bermuda Pedestal, on stalks of hexactinellid sponges, 3550 m + 3011 m (Calder 1996: 1723).— Bahamas: Cay Sal Bank, Double-Headed Shot Key, 315 ftm (576 m) (Calder & Vervoort 1998: 24; re-examination of holotype). — ? USA: Louisiana, continental slope, 540–560 m, from vestimentiferan aggregrations on water cold seeps (Bergquist et al. 2003: 205).— Bahamas: Cay Sal Bank, Double-Headed Shot Key, 315 ftm (576 m) (Peña Cantero et al. 2007: 252; re-examination of holotype).