Acryptolaria longitheca (Allman, 1877)

Peña Cantero, Álvaro L. & Vervoort, Willem, 2010, Species of Acryptolaria Norman, 1875 (Cnidaria, Hydrozoa, Lafoeidae) collected in the Western Pacific by various French expeditions, with the description of nineteen new species, Zoosystema 32 (2), pp. 267-332 : 297-298

Acryptolaria longitheca (Allman, 1877) ( Figs 15 ; 30 ; 32A ; Table 16)

Cryptolaria longitheca Allman, 1877: 18-20 , pl. 13, figs 4, 5.

Acryptolaria longitheca – Peña Cantero et al. 2007: 252- 254 , figs 9, 16A, 18B, tab. IX.

MATERIAL EXAMINED. — Loyalty Islands. BIOCAL 1, stn DW 82, 20°30.658’- 20°30.888’S, 167°50.308’- 167°50.367’E, 440-460 m, 6.IX.1985, several stems up to 20 mm high on coral (MNHN-Hy.2009-0197) ; 1 stem c. 16 mm high (MNHN-Hy.2009-0153, slide).

MUSORSTOM 6, stn DW 406, 20°40.65’S, 167°06.80’E, 373 m, 15.II.1989, 1 stem c. 18 mm high on tube of benthic organism ( MNCN 2.03 /420). — Stn DW 407, 20°40.70’S, 167°06.60’E, 360 m, 15.II.1989, 3 stems up to 70 mm high (RMNH-Coel. no. 31515); 1 basally broken stem c. 20 mm high (RMNH-Coel. no. 35161, slide 727). — Stn DW 422, 20°26.20’S, 166°40.31’E, 257 m, 16.II.1989, 2 fragments up to 11 mm long (RMNH-Coel. no. 31516). — Stn CP 464, 21°02.30’S, 167°31.60’E, 430 m, 21.II.1989, several stems up to 10 mm high on worm tube ( MNCN 2.03 /421). — Stn DW 471, 21°08.00’S, 167°54.10’E, 460 m, 22.II.1989, several stems up to 28 mm high on coral, with coppinia (MNHN-Hy.2009-0198) .

Norfolk Ridge. BIOCAL 1, stn DW 66, 24°55.435’- 24°54.849’S, 168°21.678’- 168°21.995’E, 515- 505 m, 3.IX.1985, 4 stems up to 31 mm high (RMNH-Coel no. 31517); 1 incipient stem c. 10 mm high (RMNH-Coel. no. 35229, slide 813).

SMIB 4 , stn DW 39, 24°56.2’- 24°55.4’S, 168°21.5’- 168°21.5’E, 525-560 m, 7.III.1989, one stem c. 25 mm high in slide ( MNCN 2.03 /397). — Stn DW 50, 23°42.4’- 23°41.6’S, 168°00.8’- 168°00.6’E, 260-295 m, 9.III.1989, 1 stem c. 23 mm high (MNHN-Hy.2009-0199); 1 basally broken stem c. 20 mm high (MNHN-Hy.2009-0154, slide). — Stn DW 55, 23°21.4’- 23°21.4’S, 168°04.5’- 168°04.8’E, 215-260 m, 9.III.1989, 1 stem c. 6 mm high on coral ( MNCN 2.03 /422) .

SMIB 5, stn DW 72, 23°42.0’S, 168°00.8’E, 400 m, 7.IX.1989, 2 fragments up to 11 mm long (MNCN 2.03/423).

ECOLOGY AND DISTRIBUTION. — Western Atlantic, off Double-Headed Shot Key, 567 m (Allman 1877). Our material was collected at depths between 215 and 560 m in the Loyalty Islands and Norfolk Ridge areas. It grows epibiotic on corals and tubes of benthic organisms. The colony with coppinia was collected in February.

DESCRIPTION

Stems up to 70 mm high, though usually smaller. Branching frequent (up to fifth-order branches observed) and irregular in either one or several planes, sometimes alternate ( Fig. 32A ). There may be anastomoses. Branches show slight zigzag ( Fig. 15A ).

Hydrothecae alternately arranged and roughly in one plane ( Fig. 15A ), horn-shaped ( Fig. 15 A-C); diameter at free part either constant or slightly decreasing basally, then sharply decreasing where hydrotheca becomes adnate and from there on smoothly decreasing downwards. Hydrotheca sharply bent outwards. Adcauline wall adnate for less than half its length (adnate/free ratio 0.9). Free portion of adcauline wall straight or slightly convex, adnate part initially convex but straight basally. Abcauline wall concave in general, but straight at basal and distal parts. Hydrothecal aperture circular, directed upwards, forming an angle of c. 40° with longitudinal axis of internode. Rim flared in young hydrothecae, but not everted and with many renovations in the oldest ones ( Fig. 15A, B ).

Large nematocysts relatively large and fusiform ( Fig. 30 ).

Coppinia deprived of defensive tubes ( Fig. 15D ); gonothecae closely set, with coalesced walls, bottle-shaped with a short and wide distal neck with a circular aperture ( Fig. 15D ).

REMARKS

Our material undoubtedly belongs to this species, sharing the colony structure, with slightly geniculate stems, the shape and size of the hydrothecae and the size of the nematocysts. Peña Cantero et al. (2007) give a redescription of the type material and full discussion of the species including their arguments to consider A. longitheca a valid and well-characterized species and outlining the differences with the allied species. They also consider Clarke’s (1879) record valid, because of the complete agreement with the holotype in the shape and size of the hydrothecae. Clarke also recorded coppiniae whose structure is similar to those found in our material giving additional support to the opinion expressed by the authors. Nevertheless, without having information on the cnidome of Clarke’s material, we consider it risky to consider Clarke’s material conspecific with ours, especially after the discovery of A. gemini n. sp. Acryptolaria longitheca is closely similar to A. gemini n. sp. in the general appearance of the hydrotheca, in the way they are abruptly directed outwards and in the large proportion of the free adcauline wall. They differ, however, in the distinctly smaller size of both the hydrothecae and the nematocysts (18.1 × 5.7 µm) in A. gemini n. sp., as well as in the distinct adcauline invagination of the hydrothecal wall just before becoming adnate.

Figures

FIG. 15.— Acryptolaria longitheca (Allman,1877):A, branch fragment showing hydrothecal arrangement;B, C, hydrothecae;D, coppinia fragment showing gonothecae; A, from SMIB 4 stn DW 39; B, from BIOCAL 1 stn DW 66; C, D, from MUSORSTOM 6 stn DW 471. Scale bar: A, 600 μm; B-D, 250 μm.

FIG. 30. — Outline drawings of the large type nematocysts of Acryptolaria species discussed in the present report. Scale bar: 30 μm.

FIG. 32. — Colony shape and branching in Acryptolaria Norman, 1875: A, A. longitheca (Allman, 1877), from MUSORSTOM 6 stn DW 407; B, A. medeae n. sp., holotype,MUSORSTOM 4 stn CP 195; C, A. niobae n. sp., holotype,BIOCAL 1 stn DW 08; D, A. norfolkensis n. sp., holotype, BIOCAL 1 stn DW 36; E, A. novaecaledoniae n. sp., holotype, MUSORSTOM 6 stn DW 422; F, A. profunda n. sp., holotype, MUSORSTOM 6 stn DW 422; G, A. pseudoangulata n. sp., holotype, MUSORSTOM 4 stn CP 217; H, A. pseudoundulata n. sp., holotype, MUSORSTOM 6 stn DW 457; I, A. pulchella (Allman, 1888), from MUSORSTOM 3 stn DR 117; J, A. pygmaea n. sp., holotype, SMIB 4 stn DW 60; K, A. tetraseriata n. sp., holotype, MUSORSTOM 3 stn DR 117; L, A. undulata n. sp., holotype, BIOCAL 1 stn DW 66. Scale bars: A, C, F-I, 10 mm; B, D, E, K, 20 mm; J, L, 5 mm