Iridogorgia Verrill, 1883

Xu, Yu, Watling, Les, Zhan, Zifeng & Xu, Kuidong, 2025, Studies on western Pacific gorgonians (Anthozoa: Octocorallia: Chrysogorgiidae). Part 2: unexpected diversity of the genus Iridogorgia in the tropical western Pacific with descriptions of two new species, Zootaxa 5689 (3), pp. 451-486 : 460-485

Genus Iridogorgia Verrill, 1883

Iridogorgia Verrill, 1883: 26–27 ; Versluys 1902: 91; Nutting 1908: 594; Kükenthal 1919: 538, 1924: 408; Deichmann 1936: 234; Watling 2007: 394; Xu et al. 2021: 4.

Rhodaniridogorgia Watling, 2007: 399 .

Type species: Iridogorgia pourtalesii Verrill, 1883 , by monotypy.

Diagnosis (modified after Watling 2007, Xu et al. 2021): Chrysogorgiids with branches emanating from one side of the axis or spiralling around the axis. Main axis monopodial, wavy or coiled spiraling upward with a brilliant iridescence. Polyps uniserially arranged, spaced well, when sexually mature with base expanded along upper side of branches. Sclerites rods, needles, or scales, sometimes branched or with coarse sculptures. Branch coenenchyme with sclerites oriented along branches or without sclerites between polyps.

Distribution: Western and central Pacific, north and central east Atlantic, eastern Indian Ocean, 558–2311 m ( Xu et al. 2021).

A key to the genus Iridogorgia Verrill, 1883

Based on the features of axis, branches and sclerites, a key is given to distinguish the species of Iridogorgia based on Xu et al. (2021). Iridogorgia bella , described by Nutting in 1908, is based on an incomplete type specimen with a vague original description. The true colony shape and the sclerites in each part remain unknown, necessitating further examination of the type specimen. Consequently, it is temporarily excluded from this key.

1. Colony with close helical turns...........................................................................2

– Colony with loose helical turns........................................................................... 3

2. Branches arising from the top of the colony in adults................................................. I. fontinalis

– Branches arising from nearly bottom to top of the colony in adults.............................................. 6

3. Elongated scales present in the polyp body wall............................................................. 4

– Scales absent in the polyp body wall.......................................................... I. magnispiralis

4. Sclerites in the polyp body wall usually without large tuberculate warts; small lumpy sclerites absent................. …5

– Sclerites in the polyp body wall usually sculptured by numerous large tuberculate warts; small lumpy sclerites often present.......................................................................................... .. I. squarrosa

5. Scales in the polyp body wall relatively slender and flat, surface coarse and/or rugged................... I. densispicula

– Scales in the polyp body wall stout and thick, surface relatively smooth..................................... I. flexilis

6. Colony large and tall in adults with a wavy or nearly straight axis............................................... 7

– Colony relatively short in adults with a closely coiled axis......................................................9

7. Tentacle sclerites present................................................................................8

– Tentacle sclerites absent......................................................................... I. superba

8. Sclerites with a wide range of shapes, including needles and elongated scales.............................. ... I. fragilis

– Sclerites uniform in shape, all rods........................................................ I. chewbacca sp. nov.

9. Sclerites rare to absent in the inter-polyp coenenchyme...................................................... 10

– Sclerites numerous in the inter-polyp coenenchyme......................................................... 12

10. Flat rods absent in the polyp body wall................................................................... 11

– Flat rods with irregular edges abundant in the polyp body wall......................................... I. verrucosa

11. Rods and needles with abundant fine warts in polyp body wall......................................... I. splendens

– Needles nearly smooth in polyp body wall........................................................ I. pourtalesii

12. Sclerites stout with a few flat rods present in the polyp body wall.................................... I. densispiralis

– Sclerites slender without flat rods in the polyp body wall.......................................... I. curva sp. nov.