Acryptolaria flabellum ( Allman, 1888 )

Peña Cantero, Alvaro L., Marques, Antonio C. & Migotto, Alvaro E., 2007, Revision of the genus Acryptolaria Norman, 1875 (Cnidaria, Hydrozoa, Lafoeidae), Journal of Natural History 41 (5 - 8), pp. 229-291 : 247-249

Acryptolaria flabellum ( Allman, 1888)

( Figures 7 , 15E , 17F , 19F ; Table VII)

Cryptolaria flabellum Allman 1888 , p lvii, lxii, lxviii, 40, Plate 19 Figure 1a .

Material examined

Holotype: BMNH 1888.11 .13.27, H.M.S. Challenger, Sta. 24, 18 ° 389300 N, 65 ° 059300 W, off Culebra Island , West Indies, 390 fathoms (702 m), pteropod ooze.

Description

‘‘Colony attaining a height of about one inch [25.4 mm]; hydrocaulus rigid, rooted by a thick disc-like expansion, ramification in a single plane, and irregular’’ ( Allman 1888, p 40).

Stem completely polysiphonic, ca 20 mm in height. Hydrorhiza dish-shaped. Stem slightly geniculate with six first-order branches, one with incipient secondary branch. The three more basal branches also polysiphonic; polysiphony decreasing distally.

Hydrothecae alternate, more or less in one plane. Hydrotheca cylindrical, diameter only slightly decreasing at most basal part, gently curved abcaulinarly, especially at distal part; from two-thirds to six-sevenths of adcauline wall adnate to internode. Adcauline wall convex. Abcauline wall concave at distal half, though practically straight at basal half. Hydrothecal aperture circular, parallel to longitudinal axis of branch or slightly directed upwards or downwards. Rim even, usually with numerous renovations (four to 90) which curve hydrothecal aperture downwards; the most distal hydrothecae with few short renovations. Hydrothecal perisarc longitudinally striated.

Coppinia not observed.

Remarks

The material examined lacked coenosarc, and it was almost impossible to find nematocysts; a single putative nematocyst was observed.

As noted by Allman (1888, p 40), the rigid habit, the ramification in one plane and, especially, the long curved hydrothecae make the species quite distinctive from other species of Acryptolaria .

The study of the type material of Cryptolaria flabellum has confirmed that it belongs to the genus Acryptolaria , as was already indicated by Fraser (1944) and Vervoort (1968), who based their opinions particularly on the alternate pattern of the hydrothecal arrangement.

Vervoort (1972) studied material of a species of Cryptolarella from deep waters of the tropical eastern Pacific, west of Peru, and considered it conspecific with Allman’s Cryptolaria flabellum —this fact supported his decision in transferring Allman’s species to the genus Cryptolarella . Although the material studied by Vervoort clearly belongs to the genus Cryptolarella , as can be concluded by the morphology of its gonothecae (cf. Marques et al. 2005), Allman’s species is undoubtedly a species of Acryptolaria .

Naumov (1960) described rare material sampled in the Bering and Okhotsk Seas as Cryptolaria flabellum , but Vervoort (1972) regarded it as belonging to a new species, distinct from Cryptolarella flabellum , because of the shorter hydrothecal length, the more dense sets of hydrothecae, the lack of the initial arrangement in slightly displaced pairs, and the extremely high number of distal hydrothecal renovations. According to Marques et al. (2005), Naumov’s material seems similar to the type species of Cryptolarella abyssicola , except for the presence of numerous renovations in the older (5basal) hydrothecae. This and the fact that Naumov’s material was not sufficiently described (infertile material) makes it impossible to evaluate its specific status, although we consider plausible that it belongs, indeed, to Acryptolaria flabellum .

Distribution

Off Culebra Island, 18 ° 389300 N, 65 ° 059300 W, 702 m, pteropod ooze.

Figures

Figure 1. Acryptolaria abies (Allman, 1877). (A) Part of branch showing hydrothecal arrangement; (B–F) hydrothecae. (A–C, E) From the paralectotype; (D) from the lectotype; (F) from MCZ 45714. Scale bar: 1 mm (A); 400 Mm (B–F).

Figure 7. Acryptolaria flabellum (Allman, 1888). (A, B) Branch fragments showing hydrothecal arrangement; (C, D) hydrothecae. All drawings from the holotype. Scale bar: 1 mm (A, B); 400 Mm (C, D).

Figure 15. Hydrothecal arrangement in Acryptolaria. (A) A. abies; (B) A. conferta; (C) A. corniformis; (D) A. crassicaulis; (E) A. flabellum; (F) A. gracilis. Scale bar: 500 Mm (A, B, D, E); 250 Mm (C); 100 Mm (F).

Figure 17. Shape of hydrotheca in Acryptolaria. (A) A. abies; (B) A. angulata; (C) A. conferta; (D) A. corniformis; (E) A. crassicaulis; (F) A. flabellum. Scale bar: 250 Mm.

Figure 19. Shape of gonothecae: (A) Acryptolaria conferta; (B) A. minima. Detail of different structures: (C) bottleneck-shaped basal part of hydrotheca in A. gracilis; (D) opercular structure in A. minima; (E) opercular structure in A. operculata; (F) longitudinal striae in hydrotheca of A. flabellum; (G) intrathecal cusp of A. tortugasensis. Scale bar: 100 Mm (A, B, D, F, G); 50 Mm (C); 250 Mm (E).