Paraminabea cf. aldersladei Williams & Alderslade, 1999

Bryce, Monika, Poliseno, Angelo, Alderslade, Philip & Vargas, Sergio, 2015, Digitate and capitate soft corals (Cnidaria: Octocorallia: Alcyoniidae) from Western Australia with reports on new species and new Australian geographical records, Zootaxa 3963 (2), pp. 160-200 : 186-188

Paraminabea cf. aldersladei Williams & Alderslade, 1999

( Figs. 15 D,E,F, 17A,B; 18A,B; Tab. 2)

Material examined. WAM Z59783, five whole specimens, Station 44/K10, Long Reef, Kimberley, NW Australia, 13.92155° S, 125.73268° E, scuba, depth 10–20 m, coll. M. Bryce, 20 October 2010.

Description. The colonies are either uniformly cylindrical from the base to the apical tip or are tapering toward the rounded apical end ( Fig. 15 D,E,F). They have a short, slightly laterally flattened polyp-free base. The polyps are dimorphic, and arranged uniformly over 60–90 % of the surface of the colonies. In all colonies the autozoids are completely retracted. The surface of the preserved specimens is extremely contracted and appears convoluted, which makes the siphonozooids difficult to locate. The gastric cavities of the autozooids form curved tubes ( Fig. 15 F). Colonies are between 16–24 mm tall, 3–7 mm in diameter at the apex and 5–7 mm in diameter across the holdfast.

In the surface of the polyparium the sclerites are mostly 8-radiates and some cylindrical to oval forms, 0.04 to 0.09 mm long ( Fig. 17 A), and in the interior the sclerites are double stars or double heads and irregular forms, some approaching crosses, from about 0.05 to 0.07 mm long ( Fig. 17 B). The sclerites from the base are similar to those of the polyparium, consisting mostly of 8-radiates in the surface, from 0.06 to 0.08 mm long ( Fig.18 A), and double heads or double-stars, with a long waist, together with irregular forms approaching crosses, up to 0.09 mm long, in the interior ( Fig. 18 B). Polyp sclerites are absent.

Colour. The colonies were uniformly dark red in situ and on deck. In alcohol the specimens are dark orange. The polyps in the preserved specimens are cream. The colour of the sclerites is red.

Habitat. Very steep and fractured fore-reef slope ascending from 20 up to four metres depth. The slope is heavily pocketed with small caves and deep, steep-sided fissures. At 20 metres there are large rocky outcrops forming long-reef gullies, which are almost devoid of life, probably due to the heavy siltation. Sediment between the rocky outcrops is very fine and smothering. A small group of Paraminabea cf. aldersladei was found attached to the wall together with a group of Eleutherobia kimberleyensis sp. nov. in an overhang at ten meters depth amongst other scattered soft corals.

Remarks. Paraminabea cf. aldersladei has similarities to P. aldersladei , P. indica , and P. robusta . It resembles P. aldersladei in growth form, but differs in type and distribution of the sclerites. P. aldersladei is bright orange and has mainly orange 8-radiates, double-heads, robust barrels and subspheroidal forms, while this species has red sclerites consisting predominately of radiates, double heads and complex cross-like forms. Paraminabea indica differs from Paraminabea cf. aldersladei by being dichromatic, the restriction of the polyps to less than half of the colony length, and the lack of tuberculated spheroids. It also appears to be restricted to deep water. The main differences between P. cf. aldersladei and P. robusta are colour, colony length and the morphology and distribution of the siphonozooids.

Figures

FIGURE 17. Paraminabea cf. aldersladei, WAM Z 59783, sclerites: A, surface of the polyparium; B, interior of the polyparium.

FIGURE 18. Paraminabea cf. aldersladei, WAM Z 59783, sclerites: A, surface of the base; B, interior of the base.

FIGURE 15. A – C, Paraminabea aldersladei, WAM Z 59775: A, in situ; B, a preserved specimen and fresh specimens on deck after collection; C, longitudinal section showing gastric cavities of autozooids and siphonozooids and detail of the colony surface, black arrow pointing to siphonozooids; D – F, Paraminabea cf. aldersladei, WAM Z 59783: D, in situ; E, a preserved specimen and fresh specimens on deck after collection; F, longitudinal section showing gastric cavities of autozooids and siphonozooids and detail of the colony surface, black arrow pointing to siphonozooids.