Coryne pusilla Gaertner, 1774

Peña Cantero, Álvaro L., 2022, On a few benthic hydroids (Cnidaria, Hydrozoa) from the Kerguelen Islands (southern Indian Ocean), including the description of a new species, Zootaxa 5165 (2), pp. 274-286 : 278

Coryne pusilla Gaertner, 1774

( Fig. 3A–B )

? Coryne conferta Allman, 1876: 115 ; 1879: 285, pl. 18 figs 1–3.— Studer, 1879: 121.— Vanhöffen, 1910: 274–275, fig. 1.

Material examined. PROTEKER 3: Ile Suhm , a tuft of stems up to 25 mm high, with gonophores ( MNHN IK – 2012–10428 ).

Description. Stems up to 25 mm high, unbranched or with only a few secondary stems (one stem gives rise to seven secondary stems and some of these to one, on one occasion two, third-order stems). Degree of stem annulation variable, but in general stems strong and densely ringed, smooth distally. No distal perisarc collar. Polyps with around 36 tentacles; five in a whorl around hypostome ( Fig. 3A ), the remaining with no clear arrangement.

One or two little-developed gonophores present in a few polyps, originating at axil of basal tentacles. Gonophores roughly spherical, attached by a small pedicel to hydranth body. One 340 µm high and 270 µm in maximum diameter; another 240 µm in diameter.

Cnidome consisting of stenoteles in two size classes ( Fig. 3B ): larger 20.1±1.1 x 12.9±0.7 µm (n= 10), range 18–22 x 12.0–14.0 µm, smaller 12.3±0.5 x 7.5±0.4 µm (n= 10), range 11.5–13.0 x 6.5–8.0 µm.

Remarks. Allman (1876) described Coryne conferta n. sp. from Kerguelen. His brief description, based on infertile material, precludes assigning any material to this species. The present material could be conspecific with Allman’s, agreeing in general with the few characters he described, but the species is not sufficiently characterised. Schuchert (2001) already considered C. conferta an insufficiently described species, being indistinguishable from C. pusilla or Coryne eximia Allman, 1859 .

Coryne conferta was again reported from Kerguelen, also based on infertile material, by Studer (1879) and Vanhöffen (1910); the latter from the same locality as Allman’s material.

I have assigned the present material to Coryne pusilla because it agrees with this species in the colony habit, the lack of perisarc collar at the end of the stem, the number of tentacles on the polyp and the size of the nematocysts. According to Schuchert (2001) the stems are 1–3 cm high, with five to 15 hydranths per shoot and rarely end in a funnel-shaped dilation; the polyps are provided with 18–28 tentacles. As for the size of the nematocysts, he reported stenoteles 18–23 x 11–15 µm and 12–16 x 6.5–10 µm.

Schuchert (2001) indicated that Coryne pusilla was known from Kerguelen, but without providing a direct reference. He probably refers to Vanhöffen’s (1910: 275) record, which was described just after his record of C. conferta from Kerguelen. Schuchert (2001: 849) stated that “ Vanhöffen (1910) described infertile Coryne conferta colonies from close to the type locality and also fertile colonies of Coryne pusilla on floating Fucus ”. Even when Vanhöffen’s material of C. pusilla was collected on Fucus , as Schuchert indicated, it does not come from Kerguelen, but from the English Channel. Therefore, if confirmed, the present material would represent the first record of C. pusilla in the study area.

Ecology and distribution. Coryne pusilla was collected at a depth of 14 m off Suhm Island.

Figures

FIGURE 3. Coryne pusilla Gaertner, 1774: A, distal part of polyp; B, larger and smaller stenoteles. Eudendrium tottoni Stechow, 1932: C, polyp; D, hydranth’s basal annular swelling; E, male gonophore. Tubularia sp.: F, hydranth and gonophores. Scale bar: 900 µm (F), 600 µm (F close-up), 200 µm (A), 100 µm (C, E), 50 µm (D), 10 µm (B).