Schizotricha turqueti Billard, 1906

Galea, Horia R. & Schories, Dirk, 2012, Some hydrozoans (Cnidaria) from King George Island, Antarctica, Zootaxa 3321, pp. 1-21 : 13-15

Schizotricha turqueti Billard, 1906

(Fig. 3G–K)

Schizotricha turqueti — Peña Cantero, Svoboda & Vervoort, 1996: 418, fig. 2.

Material examined. Stn. ARD — 28.i.2011, Ant.30/2011 (38 m): a stem, ca. 30 cm high, with three side branches and numerous gonothecae (presumably female), most cladia broken off (MHNG-INVE-79797). Stn. RAS — 19.i.2010, Ant.03/2010 (43 m): a colony composed of three stems, ca. 30 cm high, the first unbranched, the second with two small side branches, and the third with a single side branch, all stems richly bear gonothecae, most cladia broken off (MHNG-INVE-79806).

FIGURE 3. A–C: Oswaldella shetlandica Stepanjants, 1979 — stem apophysis and cladia (A); hydrotheca in lateral (left) and frontal (right) views (B); gonotheca (C). D–F: Oswaldella vervoorti Peña Cantero & García Carrascosa, 1998 — stem apophysis and cladia (D); hydrotheca in lateral (left) and frontal (right) views (E); internode with hydro- and gonotheca (F). G–K: Schizotricha turqueti Billard, 1906 — cauline (G) and cladial (H–J) internodes; cladial internode with hydro- and gonotheca (K). L–Q, Z1: Campanularia sp. — same hydrotheca seen in frontal (L), lateral (M), and apical (N) views; male ( O) and female (P) gonothecae, the latter containing eggs or morulae; male gonotheca in frontal (left) and lateral (right) views; cnidome (Z1). R–T, Z2: Orthopyxis norvegiae ( Broch, 1948) — hydrotheca (R); male (left) and female (right) gonothecae (S); transverse section through a male gonophore showing internal structure of the medusoid (T); cnidome (Z2). U–Z: Silicularia pedunculata ( Jäderholm, 1904) — hydrotheca atop its pedicel (U) and detail (V); female (W) and male (X) gonothecae; detail of the gonothecal aperture in frontal (left) and lateral (right) views ( Y); cnidome (Z3). Scale bars: 10 µm (Z), 200 µm (N, T), 300 µm (B, C), 400 µm (E, Y), 500 µm (A, F, G, K–M, O –S, V), 700 µm (D), 900 µm (H–J, W, X), 1 mm (U).

Description. Colonies ca. 30 cm high, arising from a rather dense tuft of hydrorhizal fibers, strongly flattened basally due to attachment on hard substrate. Stems clustered, polysiphonic, ca. 2–3 mm wide basally, unbranched or provided with one to three irregularly-set side branches. Main tube homomerously divided into hydrothecate internodes by means of transverse nodes; obscured by secondary tubes along nearly its whole length; side branches equally polysiphonic; secondary tubes undivided and provided with nematothecae only. Stem internodes long, though of varied length (1010–1660 µm), provided with a lateral apophysis, a hydrotheca and a number of nematothecae. Apophyses rather long (300–410 µm), given off alternately, coplanar or forming an obtuse angle, and carrying a nematotheca on upper side, occasionally two. Hydrotheca axillary, small, nearly as wide as deep, with slightly hypertrophied lateral walls, flanked by a pair of lateral nematothecae. Additional nematothecae occur on stem internodes as follows: generally two (occasionally one or three) below hydrotheca, and rarely one or two above it, though they are generally absent there. Hydrocladia borne on stem apophyses, the two delimited by transverse node; no ahydrothecate segments in between. Cladia homomerously divided into hydrothecate internodes by means of transverse nodes. First internode with a lateral apophysis, a hydrotheca, and a number of nematothecae. Apophysis rather long and provided with one or two nematothecae. Hydrotheca axillar in position, slightly higher that wider, with thickened walls, flanked by a pair of lateral nematothecae. Two to three nematothecae occur below hydrotheca, and generally there are none above it, though, exceptionally, only one may occur. Remainder of hydrocladium composed of hydrothecate segments bearing a hydrotheca in distal half, and three to four nematothecae: two laterals and one (occasionally two in basalmost internodes) below hydrotheca. Secondary hydrocladia occur occasionally, and no further division was observed. Secondary cladia borne on apophyses of first hydrothecate internodes of primary cladia. In a few exceptional cases, secondary hydrocladia were given off from the fifth, sixth, and seventh internodes of the primary cladia. Ahydrothecate segments between apophyses of first order cladia and second order cladia are missing, though one could rarely find some, but these are formed through regeneration of broken cladia; when they occur, they carry a single nematotheca. First internode of a second order cladium comparatively longer (1395–1565 µm) than subsequent ones (875–1095 µm); provided with a distally-placed hydrotheca flanked by a pair of lateral nematothecae, and three (rarely four) additional nematothecae below the hydrotheca. Cladial hydrothecae deeper than wide, adnate for whole of their adaxial length (160–190 µm), walls moderately thickened, rim smooth, slightly lowered adaxially; abcauline wall 265–345 µm long, straight or slightly tilted abaxially a few distance below rim; aperture of hydrotheca 190–210 µm wide in lateral view, 210–220 µm wide in frontal view. Gonothecae borne on a short (165–190 µm), tubular, thin-walled, movable pedicel originating from below the hydrothecal bases; gonothecae elongate-ovoid, 1260–1320 µm long, 490–500 µm wide, with conspicuous basal chamber delimited by circular thickening of perisarc, provided with two nematothecae; aperture distal, large, crescent-like. All nematothecae bithalamic and movable; basal chamber conical, high, separated by diaphragm from upper chamber; the latter rather shallow, with lowered rim on adaxial side.

Remarks. The present material differs from the present concept of S. turqueti , in the following respects: 1) it forms sparingly-branched stems, whilst Billard's species has unbranched stems even when it forms tall colonies (up to 38 cm, see Peña Cantero & Vervoort 2005); 2) branching of cladia attains the 2nd order only, compared to S. turqueti in which the 6th order is reached in stems of up to 20 cm high ( Peña Cantero, Svoboda & Vervoort 1996); 3) it constantly lacks double internodes, differing from S. turqueti in which their occurrence may be notable ( Peña Cantero & Vervoort 2005, 2009); and 4) slight differences in the number of nematothecae on both the cauline and cladial internodes, as well as on their apophyses.

Geographical distribution. Summarized by Peña Cantero & Vervoort (2005).