Solenoscyphus striatus, Galea, 2015

Galea, Horia R., 2015, Two new genera and nine new species of hydroids (Cnidaria: Hydrozoa) from off New Caledonia, European Journal of Taxonomy 135, pp. 1-19 : 10-12

Solenoscyphus striatus sp. nov.

urn:lsid:zoobank.org:act:6ED544D2-AD80-469D-AF97-DFE1062D6E0D

Figs 3C , 4 E–G; Table 2

Diagnosis

Colonies lightly fascicled basally; branching irregular, in one plane; nodes indistinct; each internode relatively short, bearing a hydrotheca; the latter long, tubular, facing outward and upward, apically swollen; operculum deciduous; perisarc of colonies densely and finely striated.

Etymology

From the Latin strĭātus , meaning "marked with striae", to characterize the external condition of the perisarc.

Material examined

Holotype

NEW CALEDONIA: campaign Bathus 2, station CP737, 23°03’ S, 167°00’ E, 357–400 m, 13 May 1993; sterile colony fragment 5.2 cm high (IK-2012-10295).

Paratype

NEW CALEDONIA: data as for holotype; sterile colony fragment 3.1 cm high (IK-2012-10296).

Description

Smaller specimen (paratype) 3.1 cm high, comprising a branched fragment of either a stem or a side branch; larger specimen ( Fig. 3C , holotype) 5.2 cm high, possibly a branched stem missing hydrorhiza; both possibly originally parts of a single colony with multiple stems. This colony obviously fascicled to an unknown extent, as largest available fragment comprises an accessory tube running up both main stem and basal part of lowest side branch. Division into internodes indistinct; each equivalent of internode relatively short, carrying a single hydrotheca on distal half. Branching pattern irregular and sparing, with up to second order side branches given off laterally from below bases of hydrothecae; side branches with same structure as stem; proximal-most internode comparatively longer than following ones. Hydrothecae biseriate and alternate; tubular in shape, adnate for slightly more than one-third of adaxial length, facing up- and outward; abaxial wall almost straight, except for proximal part, which is convex at point where hydrotheca becomes free on opposite side; free adaxial side straight and parallel to adaxial counterpart. Apical part of hydrotheca distinctly swollen and there perisarc much thinner than elsewhere; rim indistinctly tilted adaxially; rounded, thin operculum present in some hydrothecae; point of attachment indeterminable; deciduous. External perisarc finely and densely striated over entire colony. Gonothecae unknown; scar below one hydrotheca suggests at least one gonotheca was present and subsequently lost; numerous large foramina (obliterated by thin pellicle of perisarc) indicate that colony was about to become fertile.

Remarks

Although not resembling either S. candelabrum gen. et sp. nov. or S. decidualis gen. et sp. nov. in colony shape, the present species nevertheless possesses a deciduous operculum, which is one of the main features of the newly described genus.

Unlike S. candelabrum gen. et sp. nov., both S. decidualis gen. et sp. nov. and the present species possess long, tubular hydrothecae with straight axes. However, their adnate parts are longer and their apertures are wider in S. striatus gen. et sp. nov. Additionally, the entire perisarc of the latter is finely and densely striated.

Figures

Fig. 3. A. Solenoscyphus candelabrum gen. et sp. nov., colony silhouette (holotype). B. Solenoscyphus decidualis gen. et sp. nov., colony silhouette (holotype). C. Solenoscyphus striatus gen. et sp. nov., colony silhouette (holotype). Scale bars: A = 2 cm; B–C = 1 cm.

Fig. 4. — A–B. Solenoscyphus candelabrum gen. et sp. nov. A. Portion of stem with basal parts of five cladia. B. Hydrotheca, showing internal projections of the perisarc. — C–D. Solenoscyphus decidualis gen. et sp. nov. C. Portion of stem with basal parts of two consecutive cladia. D. Hydrotheca. — E–G. Solenoscyphus striatus gen. et sp. nov. E. Portion of stem with basal part of a side branch. F. Hydrotheca, showing the characteristic striation of the perisarc. G. Operculum. Scale bars: A, C, E = 2 mm; B, D, F = 500 μm; G = 300 μm.