Symplectoscyphus

Galea, Horia R., Schories, Dirk, Försterra, Günter & Häussermann, Verena, 2014, New species and new records of hydroids (Cnidaria: Hydrozoa) from Chile, Zootaxa 3852 (1), pp. 1-50 : 41

Symplectoscyphus sp.

(Plate 3E; Fig. 8 E–H)

Material examined. HF9, Isla Magel, lat. -54.92655, long. -67.41338, 19.xii.2010, 6 m, sample C281: colony on seaweed, composed of several stems (up to 4.5 cm high) and smaller fragments, and a single gonotheca.

Description. Colony 4.5 cm high, fan shaped, delicate (Pl. 3E). Stems monosiphonic with a few annuli above origin from stolon, then regularly divided into oblique internodes by constrictions of the perisarc. Each internode with 3 alternate hydrothecae and a lateral apophysis given off from below the distalmost hydrotheca, the latter becoming axillar ( Fig. 8 E); presence of apophysis introduces a bent in the structure of the stem. Cladia borne of corresponding stem apophyses, junction marked by transverse node. Cladia given off in same plane as the stem, conferring the whole colony a planar appearance; divided into regular internodes by oblique nodes, each carrying a distally placed hydrotheca. Cladia almost straight, unless the presence of a lower order branch introduces a bend, like in the stem; up to 4th order branches, lower order ones given off irregularly. Hydrothecae alternate on both stem and branches, and rather distant; tubular, adnate for half their adaxial length; abaxial wall slightly swollen basally, becoming convex distally; free adaxial wall almost straight ( Fig. 8 F); aperture with three triangular cusps separated by rather deep embayments; a conspicuous abaxial, submarginal cusp projects to a varied degree into the lumen of hydrotheca ( Fig. 8 G). A single gonotheca, of undetermined sex, arises from below the base of a stem hydrotheca; immature, with distal part incomplete; wall with nine free, independent ribs ( Fig. 8 H).

Remarks. This species somehow resembles S. filiformis ( Allman, 1888) in the colony structure and the shape of hydrotheca. Its gonotheca, though incomplete, recalls also that of Allman’s species. However, the presence of a prominent abaxial, submarginal cusp is not a feature met with in any of the numerous specimens of S. filiformis examined so far. Its identification to species is pending the discovery of specimens with fully formed gonothecae.

Distribution in Chile. Magel Island (present study).

Figures

FIGURE 8. A ‒ D: Symplectoscyphus unilateralis (Lamouroux, 1824) — stem fragment (A); hydrotheca (B); gonotheca in frontal (C) and lateral (D) views. E ‒ H: Symplectoscyphus sp. — colony fragment (E); hydrotheca in lateral (F) and apical (G) views; gonotheca (H). I, J: Staurotheca jaederholmi Stechow, 1920 — colony fragment (I); gonothecae (J). K ‒ M: Parascyphus simplex (Lamouroux, 1816) — stem fragment (K); hydrotheca (L) and detail of aperture (M). N, O: Halopteris plumosa Galea & Schories, 2012 a—female (N) and male (O) gonothecae. Scale bars: 200 µm (A, B, F, G), 300 µm (C, D, L ‒ O), 500 µm (H, K), 1 mm (E, I, J).