Palythoa cf. heliodiscus (Ryland & Lancaster, 2003)

Reimer, James D., Poliseno, Angelo & Hoeksema, Bert W., 2014, Shallow-water zoantharians (Cnidaria, Hexacorallia) from the Central Indo-Pacific, ZooKeys 444, pp. 1-57 : 10-11

Taxon classification Animalia Zoantharia Sphenopidae

8. Palythoa cf. heliodiscus (Ryland & Lancaster, 2003) Figures 7, 8

Specimens examined

(n=2). RMNH Coel 40504, Fauna Malesiana Maluku Expedition station MAL.12, north coast near Morela, Ambon, Moluccas (03°33'S, 128°12'E), depth = 35 m, collected on November 13, 1996; RMNH Coel. 40513, Rumphius Biohistorical Expedition station 24, south Seri Bay, Ambon, Moluccas (03°34'50"S, 128°09'45"E), depth = 12 m, November 22, 1990.

Photographic records

(n=13). Pulau Ular, off Padang, West Sumatra (01°07'05"S, 100°20'02"E), December 16, 1996; Pemuteran, West Bali (08°11'20"S, 114°50'30"E), May 23, 1998; Tulamben, eastern Bali (08°16'26"S, 115°35'28"E), July 12, 1997; Nusa Lembongan, Lombok Strait (08°40'S, 115°26'E), May 29, 1998; west side Pulau Samalona, Spermonde Archipelago, South Sulawesi (05°07'25"S, 119°20'10"E), November, 1984; northwest side Pulau Samalona, Spermonde Archipelago, South Sulawesi (05°07'25"S, 119°20'10"E), November 23, 1997; northwest Kudingareng Keke, Spermonde Archipelago, South Sulawesi (05°06'15"S, 119°17'10"E), August 6, 1997; west side Pulau Badi, Spermonde Archipelago, South Sulawesi (04°58'06"S, 119°16'57"E), November 1, 1994; REA Wakatobi National Park station WAK.18, southwest Pulau Binongko, Southeast Sulawesi, Wakatobi, Tukang Besi Islands (05°59'48"S, 124°02'55"E), May 10, 2003; REA Wakatobi National Park station WAK.22, north channel pass of Karang Koromaha, Southeast Sulawesi, Wakatobi, Tukang Besi Is. (05°42'54"S, 124°10'53"E), May 12, 2003; Fauna Malesiana Maluku Expedition station MAL.12, north coast near Morela, Ambon (03°33'S, 128°12'E), November 13-14, 1996; East Kalimantan–Berau Expedition station BER.03, south side of Pulau Derawan, East Kalimantan (02°17'03"N, 118°14'49"E), October 16, 2003; Christensen Research Institute, Madang, Papua New Guinea (05°09'30"S, 145°48'10"E), June 1992.

Description.

This zooxanthellate species was described in detail recently by Ryland and Lancaster (2003). Superficially similar in appearance to Palythoa mutuki , externally the species can be distinguished by its short tentacles (length <20% of oral disk) and subtidal distribution, compared to primarily intertidal Palythoa mutuki , which also has longer tentacles (~45% of oral disk) ( Ryland and Lancaster 2003).

Sizes of specimens agree well with specimens seen in other localities (average polyp heights 11.3 mm and 17.0 mm for each specimen, range 7-20 mm; average width 3.9 mm and 4.4 mm for each specimen, range 3.5-5.5 mm; n=2 specimens of 8 and 5 polyps, respectively). Depth of collected specimens (12 and 35 m) also fits well with the description of this species as primarily subtidal in the original description, and from data in Okinawa, Japan (e.g. Reimer 2010).

Distribution.

Regions recorded in this study (Figure 7). West Bali (4), eastern Bali (5), Spermonde Archipelago (9), Tukang Besi Islands (12), Moluccas (14).

Previous records. Palythoa heliodiscus has been reported from Australia ( Ryland and Lancaster 2003) and is likely widespread in the Indo-Pacific ( Ryland and Lancaster 2003 and references within), as well as Japan ( Reimer et al. 2006b), Palau ( Reimer et al. 2014a), while Palythoa toxica Walsh & Bowers, 1971 has been reported from Hawai’i.

Remarks.

We have identified all specimens here as “cf.” as in situ images (Figure 8) there are two different morphotypes. One morphotype matches with Palythoa heliodiscus , with a brown oral disk with no patterns (Figures 8A, B), while the other morphotype’s polyps have either green or purple oral disks with various semi-irregular patterns, as well as blue/gray or light orange tentacles (Figures 8C, D). Based on data from Okinawa and Australia, both of these morphotypes are almost identical asides from the oral disk coloration and small but consistent differences in ITS–rDNA (T. Nishimura and J.D. Reimer, unpubl. data) that may be either intraspecific or interspecific. Thus, it is still uncertain if the green/purple morphotype is an undescribed species or not ( Reimer et al. 2014a).

Furthermore, the overall morphology of the green/purple morphotype closely resembles Palythoa toxica from Hawai’i, and whether these Indonesian specimens are Palythoa toxica or Palythoa heliodiscus , and if these two species are synonyms needs to be ascertained before any formal description occurs. In situ images and further DNA sequences are therefore needed from future specimens.