Table 1 in Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae

Table 1. Main distinguishing characters of the genera belonging to the family Ptychogastriidae Mayer, 1900. UmbrellaGlaciambulata gen. nov. FlatPtychogastria Allman, 1878 Dome-shapedTesserogastria Beyer, 1959 Dome-shapedManubriumEight-lobedEight-lobedFour-lobedMesenteries88AbsentTentaclesFiliform + adhesive; forming contiguous groups; inserted in superimposed rows on umbrella marginFiliform + adhesive; forming contiguous groups; inserted in superimposed rows on umbrella marginFiliform; reportedly not arranged in groups; inserted at varied levels on umbrella marginCentripetal canalsAbsentPresent/absentAbsentGonadsOvoid; in pairs, on either side of the manubrial lobesOvoid; in pairs, on either side of the manubrial lobesElongated; simple; attached to the body of manubriumVelumAbsentPresentPresentStatocysts16168Ability to swimNoYesYes表1 1900年Mayer建立的褶腹水母科（Ptychogastriidae）各属的主要鉴别特征。各属的分类鉴别特征如下：1. 伞部形态：Glaciambulata新属（Glaciambulata gen. nov.）伞体扁平；褶腹水母属（Ptychogastria Allman, 1878）与四褶腹水母属（Tesserogastria Beyer, 1959）伞体均呈圆顶形。2. 口盘分叶：Glaciambulata新属与褶腹水母属的口盘均为8叶；四褶腹水母属的口盘为4叶。3. 隔膜数目：Glaciambulata新属与褶腹水母属的隔膜数均为8；四褶腹水母属无隔膜。4. 触手特征：Glaciambulata新属与褶腹水母属的触手均为丝状且具黏着性，形成连续群组，以叠生行列着生于伞缘；四褶腹水母属的触手为丝状，据报道不成群，以不同高度着生于伞缘。5. 向心管：Glaciambulata新属与四褶腹水母属均无向心管；褶腹水母属的向心管存在与否不定。6. 生殖腺：Glaciambulata新属与褶腹水母属的生殖腺呈卵圆形，成对生于口盘叶两侧；四褶腹水母属的生殖腺为长椭圆形、单生，附着于口盘体部。7. 缘膜：Glaciambulata新属无缘膜；褶腹水母属与四褶腹水母属均有缘膜。8. 平衡囊数目：Glaciambulata新属与褶腹水母属的平衡囊数目均为16个；四褶腹水母属的平衡囊数目为8个。9. 游泳能力：Glaciambulata新属无游泳能力；褶腹水母属与四褶腹水母属均具游泳能力。