Caledoniana, Galea, 2015

Galea, Horia R., 2015, Two new genera and nine new species of hydroids (Cnidaria: Hydrozoa) from off New Caledonia, European Journal of Taxonomy 135, pp. 1-19 : 2-3

Genus Caledoniana gen. nov.

urn:lsid:zoobank.org:act:7D2C6D92-C02C-4977-A568-4A5F277389A4

Diagnosis

Erect, loosely-branched, fan-shaped, weakly-fascicled colonies; branching pattern sparing and irregular; division into internodes indistinct; hydrothecae given off in opposite, though not contiguous pairs, except for the first hydrothecae of the side branches which are unpaired; successive pairs of hydrothecae either coplanar or, occasionally, adopting a decussate arrangement; hydrothecae very large, tubular, free for at least half their length, closed by rounded, deciduous opercula; gonothecae club-shaped to piriform, inserted slightly laterally, below the hydrothecal bases.

Etymology

Named after the area of occurrence of its species, New Caledonia. The genus name is a feminine noun.

Type species

Caledoniana alata sp. nov.

Remarks

The new genus is provisionally placed within the family Sertulariidae owing to the presence of hydrothecal opercula, though molecular analyses, based on freshly-collected samples, are needed to confirm this.

Together with Gigantotheca Vervoort & Watson, 2003 , Caledoniana gen. nov. is distinguished from other genera through the presence of huge, tubular hydrothecae, both genera forming a clearly distinct group within the family. Unlike Gigantotheca , in which the hydrothecae are alternate, those of Caledoniana gen. nov. are grouped in opposite pairs, analogous to the generic separation of Hincksella Billard, 1918 and Synthecium Allman, 1872 , respectively, in the family Syntheciidae .

The hydrothecae of Caledoniana gen. nov. superficially resemble those of Staurotheca Allman, 1888 , especially through the presence of deciduous opercula with no definite points of attachment (see Peña Cantero et al. 1997: 336). However, the hydrothecae of the latter are arranged in two or multiple longitudinal rows, they are generally deeply immersed in both stems and branches, and their size is much smaller in all species described so far ( Peña Cantero et al. 1997, 1999; Peña Cantero & Vervoort 2003 a, 2003b).

Staurotheca megalotheca Vervoort & Watson, 2003 , a species of so far uncertain generic position, possesses huge hydrothecae arranged in either opposite pairs or decussate groups of three ( Vervoort & Watson 2003), suggesting obvious affinities with Caledoniana gen. nov., in particular with C. decussata sp. nov. (see below).

Key to species

1. Free part of hydrothecae curved upward ………………………………………… C. alata sp. nov.

– Free part of hydrothecae straight …………………………………………………………………2

2. Some pairs of hydrothecae adopting a decussate arrangement ……………… C. decussata sp. nov.

– Successive pairs of hydrothecae always coplanar ………………………… C. microgona sp. nov.