Acryptolaria gemini, Peña Cantero & Vervoort, 2010

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 : 290-291

Acryptolaria gemini n. sp.

( Figs 10 ; 30 ; 31G ; Table 11)

TYPE MATERIAL. — Vanuatu. Gemini Seamount , GEMINI, stn DW 60, 20°59.9’S, 170°16.6’E, 190 m, 6.VII.1989 1 broken stem c. 45 mm high, holotype (MNHN- Hy.2009-0161) ; 1 stem and several fragments, paratype (RMNH-Coel. no. 31511).

ETYMOLOGY. — The specific name “ gemini ” has been taken from the locality, the Gemini Seamount; it is a noun in apposition.

ECOLOGY AND DISTRIBUTION. — Acryptolaria gemini n. sp. was collected at a depth of 190 m in the remote Gemini Seamounts area (20°59.9’S, 170°16.6’E).

DESCRIPTION OF THE HOLOTYPE

Stem c. 45 mm high, broken into three main stem fragments. Hydrorhiza dish-shaped. Branching frequent and irregular, more or less in one plane, though secondary branches may arise in several planes ( Fig. 31G ). The stem gives rise to several primary branches,some of which get much developed and form a few second-order branches; secondary branches quite distal. Branches approximately straight ( Fig. 10A, B ).

Hydrothecae alternately arranged and roughly in one plane ( Fig. 10A, B ). Hydrotheca horn-shaped ( Fig.10 ); diameter progressively decreasing from aperture, where it is maximal, to base, but with a sharp reduction at the point where the hydrotheca becomes adnate. Hydrotheca sharply directed outwards; adcauline wall free for more than half its length (adnate/ free ratio 0.8). Free portion of adcauline wall slightly convex, adnate part roughly straight. 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 branch. Rim even, usually with renovations.

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

Coppinia not observed.

REMARKS

Acryptolaria gemini n. sp. closely resembles A. longitheca (Allman, 1877) . The similarities and differences will be discussed below, when dealing with the latter.

Figures

FIG. 10. — Acryptolaria gemini n. sp., from GEMINI stn DW 60: A, B, branch fragments showing hydrothecal arrangement; C, D, hydrothecae. Scale bar: 250 μm.

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

FIG. 31. — Colony shape and branching in Acryptolaria Norman, 1875: A, A. angulata (Bale, 1914), from MUSORSTOM 6 stn DW 487;B, A. bathyalis n. sp., holotype, MUSORSTOM 6 stn CP 419; C, A. bulbosa (Stechow, 1932), from MUSORSTOM 6 stn CP 419; D, A.disordinata n.sp.,holotype,MUSORSTOM 4 stn DW 197;E, A. encarnae n. sp., holotype,MUSORSTOM 6 stn CP 464;F, A.flabelloides n. sp., from SMIB 4 stn DW 36; G, A. gemini n. sp., holotype, GEMINI stn DW 60; H, A. infinita n. sp., holotype, MUSORSTOM 4 stn DW 197; I, A. intermedia n. sp., holotype, CHALCAL 2 stn DW 76; J, A. inversa n. sp., holotype, MUSORSTOM 6 stn DW 476; K, A. laertesi n. sp., holotype, MUSORSTOM 6 stn DW 425. Scale bars: A, C, F, G, I, 10 mm; B, D, E, H, J, K, 20 mm.