Gonaxia amphorifera Vervoort, 1993

Galea, Horia R., 2016, Notes on some sertulariid hydroids (Cnidaria: Hydrozoa) from the tropical western Pacific, with descriptions of nine new species, European Journal of Taxonomy 218, pp. 1-52 : 7

Gonaxia amphorifera Vervoort, 1993

Figs 2A , 3 A–B

Gonaxia amphorifera Vervoort, 1993: 117 , figs 3f, 4, 5, 6a–b, 8a.

Material examined

SMIB 6: Stn. DW127, two colonies, one unbranched and 4.5 cm high, the other forked twice and 9 cm high, both bear male gonothecae (MNHN-IK-2012-16521).

Remarks

The difficulty of distinguishing G. amphorifera from G. ampullacea Vervoort, 1993 without their female gonothecae is notorious. Since the present material bears only male gonothecae, attention was focused on the hydrothecal features, in an attempt to separate them specifically. Although Vervoort (1993) emphasized several distinguishing characters, the distinction was still laborious and, eventually, two features proved useful. It was found that in the present species the free, distal part of the hydrocladial hydrothecae was constantly set at about 90° with the axis of the cladia, regardless the position of the thecae ( Fig. 2A ) while, in the following species, that angle varied considerably ( Fig. 2B ) between the proximal hydrothecae (where it was of 80–90°) and the distalmost ones (usually reaching 45°). The size of the hydrothecae was comparatively smaller in the present material ( Fig. 3A ) than in that assigned to G. ampullacea Vervoort, 1993 ( Fig. 3C ). I believe that the lack of a distinct inflation of the hydrothecae invoked by Vervoort is misleading.

Some hydrothecae exhibit incipient lateral diverticuli ( Fig. 3A ). Their structure is discussed under G. aff. similis Vervoort, 1993 .

Geographical distribution

New Caledonia ( Vervoort 1993; present study).

Figures

Fig. 2. ― A. Gonaxia amphorifera Vervoort, 1993 (SMIB 6, Stn. DW127), portion of stem with cladium. ― B. Gonaxia ampullacea Vervoort, 1993 (BATHUS 4, Stn. DW914), portion of stem with cladia. ― C. Gonaxia compacta Vervoort, 1993 (BATHUS 4, Stn. DW923), portion of stem with cladium. ― D. Gonaxia intermedia Vervoort, 1993 (BATHUS 4, Stn. CP906), portion of stem with cladium. ― E. Gonaxia sinuosa Vervoort, 1993 (SMIB 4, Stn. DW40), portion of stem with cladia. Scale bar: A–E = 1 mm.

Fig. 3. ― A–B. Gonaxia amphorifera Vervoort, 1993 (SMIB6, Stn. DW127). A. Two successive cladial internodes with their hydrothecae. B. Portion of stem with male gonothecae. ― C–D. Gonaxia ampullacea Vervoort, 1993 (BATHUS 4, Stn. DW914). C. Two successive cladial internodes with their hydrothecae. D. Portion of stem with male gonothecae. ― E–F. Gonaxia compacta Vervoort, 1993 (BATHUS 4, Stn. DW923). E. Two successive cladial internodes with their hydrothecae. F. Abortive gonotheca (of undetermined sex) originating from within a hydrotheca. ― G–K. Gonaxia intermedia Vervoort, 1993 (BATHUS 4). G. Two successive cladial internodes with their hydrothecae (Stn. CP906). H. Portion of stem with male gonothecae (Stn. CP906). I. Portion of stem with female gonothecae (Stn. CP906). J–K. Abortive gonothecae arising from hydrothecal lumina (Stn. DW902). ― L–N. Gonaxia sinuosa Vervoort, 1993 (SMIB 4, DW40). L. Two successive cladial internodes with their hydrothecae. M–N. Two female gonothecae. Scale bars: A, C, E, G, L = 300 µm; B, D, F, H–K, M–N = 1 mm.