Schizotricha anderssoni Jaderholm 1904

Schizotricha anderssoni Jäderholm, 1904

Schizotricha anderssoni: Peña Cantero and Vervoort 1999, p 356 –357 (synonymy).

Material examined. 575/032, several stems up to 170 mm high, with gonothecae (USNM 1025562; RMNH-Coel. 30948; MNCN 2.03/315); 575/033, numerous stem fragments (up to 290 mm long), with gonothecae (USNM 1025563; RMNH-Coel. 30949; MNCN 2.03/316); 575/085, one fragmented stem, at least 130 mm high (USNM 1025564; RMNH-Coel. 30956; MNCN 2.03/317); 575/094, several stem fragments up to 70 mm long (USNM 1025565); 575/095, a few fragments up to 70 mm long (USNM 1025566); 601/007, one stem ca 280 mm high, with gonothecae (USNM 1025567; RMNH-Coel. 30958; MNCN 2.03/318); 601/011, two distal stem fragments up to 17 mm long, with gonothecae (in slide) (USNM 1025568); 601/014, one stem ca 190 mm high, with gonothecae (USNM 1025569); 601/057, one fragmented stem (largest fragment ca 95 mm), with immature gonothecae (USNM 1025570; RMNH-Coel. 30960; MNCN 2.03/319); 601/065, one stem ca 170 mm high, with gonothecae (USNM 1025571; RMNH-Coel. 30961); 601/074, one stem ca 50 mm high (USNM 1025572); 601/077, one stem at least 260 mm high, with gonothecae (USNM 1025573; RMNH-Coel. 30962; MNCN 2.03/ 320).

Diagnosis. Colonies with branched stems. Main cauline tube divided into simple hydrothecate internodes with two to five infrathecal nematothecae (occasionally also with one or two suprathecal nematothecae). Cauline apophysis with one nematotheca. Hydrocladia up to second order present. Frequently, apophysis supporting secondary hydrocladia followed by an ahydrothecate intermediate internode provided with two nematothecae. Hydrocladia regularly divided into internodes. Unforked hydrocladial internodes with three to six infrathecal nematothecae (occasionally also with one or two suprathecal nematothecae). Hydrotheca deep. Forked hydrocladial internodes with three or four infrathecal nematothecae (occasionally also with one or two suprathecal nematothecae). Hydrocladial apophyses with one nematotheca.

Remarks. Schizotricha anderssoni has much branched stems; indeed, there is continuous branching of the stem. Moreover, this species usually lacks branched hydrocladia. When branched, hydrocladia are either merely bifurcated or they become lower-order stems. Schizotricha anderssoni usually lacks intermediate ahydrothecate internodes in the hydrocladia, except in those becoming lower-order stems.

Ecology and distribution. Schizotricha anderssoni is a shelf species (Peña Cantero and Vervoort 1999), having been collected at depths from 75 (Jäderholm 1904) to 800 m (Naumov and Stepan’yants 1962) on stony bottoms (Peña Cantero and García Carrascosa 1995). Our material comes from depths between 68 and 346 m. Colonies with gonothecae were found in May (Jäderholm 1904) and in December (Peña Cantero and García Carrascosa 1995); our fertile colonies were collected in May, November and December. This species also serves as a substratum for other hydroids (Lafoea sp., Sertularella sp. and Symplectoscyphus sp.).

Schizotricha anderssoni seems to have a circum-Antarctic distribution (Peña Cantero and Vervoort 1999). It is known to occur off South Georgia (Jäderholm 1904; Peña Cantero and García Carrascosa 1995; present material), in West Antarctica, and in the Ross Sea (Naumov and Stepan’yants 1962) in East Antarctica.