Paraminabea aldersladei (Williams, 1992)

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 : 184-186

Paraminabea aldersladei (Williams, 1992)

( Figs. 15A,B,C ; 16A–D; Tab. 2)

Bellonella indica (non Thomson & Henderson, 1905) Bayer 1974: 261; Faulkner and Chesher 1979: 267, Pl. 22; Minabea aldersladei Williams, 1992: 3 –9, Figs 1 b, 4, 5.

Material examined. WAM Z59775, five whole specimens, Station 43/K10, Long Reef, Kimberley, NW Australia, 13.92155° S, 125.73268° E, scuba, depth 12–20 m, coll. M. Bryce, 20 October 2010; WAM Z66736, six whole specimens, Station 115/K11, Heritage reef, Kimberley, NW Australia, 14.30367° S, 115.20915° E, scuba, depth 12–20 m, coll. M. Bryce, 22 September 2011; WAM Z67010, four whole specimens, Station 130/K13, Ashmore Reef, NW Australia, 12.18848° S, 123.12887° E, scuba, depth 12–20 m, coll. M. Bryce, 29 September 2013; WAM Z67106, 33 whole specimens, Station 144/K13, Hibernia Reef, NW Australia, 11.97404° S, 123.32208° E, scuba, depth 14 m, coll. M. Bryce, 5 October 2013; WAM Z67241, 24 whole specimens, Station 152/K14, Clerke Reef, NW Australia, 17.25188° S, 119.38378° E, scuba, depth 16 m, coll. M. Bryce, 3 October 2014; WAM Z67271, 1 whole specimens, Station 156/K14, Clerke Reef, NW Australia, 17.29298° S, 119.37819° E, scuba, depth 16 m, coll. M. Bryce, 5 October 2014; WAM Z67366, 1 whole specimens, Station 170/K14, Clerke Reef, NW Australia, 17.31697° S, 119.38378° E, scuba, depth 15 m, coll. M. Bryce, 10 October 2014; WAM Z67385, 1 whole specimens, Station 173/K14, Clerke Reef, NW Australia, 17.31753° S, 119.31216° E, scuba, depth 15 m, coll. M. Bryce, 11 October 2014; WAM Z67404, 2 whole specimens, Station 178/K14, Mermaid Reef, NW Australia, 17.16154° S, 119.6471° E, scuba, depth 15 m, coll. M. Bryce, 13 October 2014.

Description. All colonies are digitiform, slightly laterally flattened, tapering toward the rounded apical end and have a short, polyp-free base ( Fig. 15A,B,C ). They are between 10–53 mm tall, 4–18 mm in diameter at the apex and 4–25 mm in diameter across the holdfast. The polyps are dimorphic, and arranged uniformly over the surface of the colonies. In all colonies the autozooid polyps are completely retracted and surrounded by minute pores representing the siphonozooids.

Sclerites from the polyparium surface are predominantly eight radiates with double heads, that appear to be derived from 6- and 8-radiates, 0.04–0.09 mm long ( Fig. 16 A). Those from the interior of the polyparium are more robust barrels and sub-sheroidal forms of similar size with a very short waist ( Fig. 16 B). Sclerites from the base surface and interior are similar in shape to those of the polyparium, but slightly longer, 0.05–0.11 ( Fig. 16 C,D). Polyp sclerites are absent.

Colour. The colonies were uniformly bright orange in situ, on deck and in alcohol. The polyps in the preserved specimen are cream. Sclerite colour is orange.

Habitat. Station 43/K10: steep outer reef wall descending to 20 meters where the bottom is of fine silt. From there the honeycombed wall extends upwards with encrusting corals and soft corals, which rapidly increase in coverage. Specimens of Paraminabea aldersladei were found attached to the wall between 12 and 20 metres.

Station 115/K11: fore-reef slope with a vertical wall descending down to a coral rubble bottom. The reef crest has a high diversity of hard and soft corals, sea fans, and sponges. The vertical wall has small caves and ledges with little benthic invertebrate life. Specimens of Paraminabea aldersladei were attached to the wall between 12 and 20 metres.

Station 130/K13: a very steep and fractured fore-reef slope descending to a depth of 20 metres. The slope is deeply incised with caves and small ledges which are well covered with encrusting invertebrates. The small group of Paraminabea aldersladei colonies was found attached to a wall in an overhang at 20 metres depth.

Station 144/K13: the fore - reef cemented slope consists of separate "hillocks" that are joined at the base with deep "gullies" between. There is a high diversity of soft and hard corals and an abundant occurrence of Paraminabea aldersladei . The colonies were attached to the walls under overhangs amongst other scattered soft corals.

Remarks. Paraminabea aldersladei is a well-known species from the Indo-Pacific (Williams 1992; Table 2). In Australia P. aldersladei has been reported from the Great Barrier Reef and also from the Rowley Shoals, northwestern Australia. The characters of this material agree well with the original description by Williams (1992, although no yellow colonies were encountered.

Figures

FIGURE 1. Location of the Kimberly region and collection sites.

FIGURE 16. Paraminabea aldersladei, WAM Z 59775, sclerites: A, surface of the polyparium; B, interior of the polyparium; C, surface of the base; D, 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.