Staurotheca Allman 1888

Staurotheca Allman, 1888

Type species, by monotypy, Staurotheca dichotoma Allman, 1888.

Diagnosis (modified from Peña Cantero et al., 1997). Colonial hydroids either without distinct stem and of bushy appearance, or with distinct, erect stem and palmate or tree-like. Branching in one or in several planes; irregular, alternate or (sub)dichotomous. Hydrotheca tubular, slightly or strongly outwardly directed, proximally as wide as or wider than distally, partly to almost completely immersed into stem or branch, arranged either in two longitudinal rows of opposite, subopposite or alternate hydrothecae or in decussate series (pairs or verticils), forming a double number of longitudinal rows of hydrothecae; along length of main stem and branches this number decreases or remains constant. Hydrothecal aperture circular (rim even) or laterally depressed (rim uneven with either abcauline elevation or with abcauline and adcauline elevations). Hydrothecal operculum circular, deciduous, point of attachment indistinct. Diaphragm in hydrothecal bottom frequently mushroom-shaped in vertical view (i.e. with two abcauline perisarc projections pointing towards hydrothecal lumen). Hydranth without abcauline caecum. Colonies dioecious, with sexual dimorphism. Male gonotheca inserted directly at hydrothecal base [in S. vervoorti (El Beshbeeshy) also emerging from hydrotheca], fusiform, with a small opening at distal end, with or without neck. Female gonothecae either directly inserted at hydrothecal base or on special supporting structures. Female gonotheca either ovoid with a more or less modified wide distal neck, or globiform and without neck. Cnidome comprising microbasic mastigophores, usually in two size classes.