Caledoniana decussata sp. nov.

urn:lsid:zoobank.org:act: B302DBC1-9E6F-427F-A3B6-3843F8FAE77C

Figs 1B, 2 C–D; Table 1

Diagnosis

Colonies lightly fascicled basally, loosely branched, coplanar; nodes indistinct, internodes relatively short; hydrothecae in opposite pairs in both coplanar and decussate series; long, tubular, free part straight.

Etymology

From the Latin dĕcusso, meaning "to form or create a cross in the form of an X", to characterize the arrangement of the hydrothecal pairs in this species.

Material examined

Holotype

NEW CALEDONIA: campaign Bathus 2, station CP737, 23°03’ S, 167°00’ E, 357–400 m, 13 May 1993; 5.5 cm high, sterile colony attached to mineral concretion and adjacent sponge, as well as 3 smaller fragments detached from it (IK-2012-10289).

Description

Colony erect, 5.5 cm high, arising from rhizoid stolon firmly attached to substrate. Basal part of stem fascicled, with several accessory tubes creeping over main tube; in monosiphonic parts, division into internodes indistinct; each equivalent of internode relatively short, bearing a pair of opposite, though not contiguous, hydrothecae. Branching sparse and irregular, up to 2 nd order; side branches given off singly or in pairs from below a stem hydrotheca; stem and side branches coplanar; structure of latter similar to that of stem, except for first hydrotheca, which is usually unpaired, though a pair of hydrothecae also occurs within colony. Basal parts of stem and side branches with successive pairs of hydrothecae in coplanar series; more distally, pairs become decussate. Hydrothecae large, tubular, adnate for about half of length, or less, to corresponding internodes; free part bent at about 45°; diameter nearly constant throughout, slightly expanding at rim; rim conspicuously thickened; aperture circular in frontal view; opercula not seen. Gonothecae absent, though basal remains at insertion of one of these (below a hydrotheca) present; numerous, large foramina (obliterated by thin pellicle of perisarc) below most hydrothecae, making the possibly future insertion points for them. Coenosarc badly preserved, not suitable for tentacle counting or cnidome studies.