Sphenopus marsupialis (Gmelin, 1791)

Reimer, James D., Poliseno, Angelo & Hoeksema, Bert W., 2014, Shallow-water zoantharians (Cnidaria, Hexacorallia) from the Central Indo-Pacific, ZooKeys 444, pp. 1-57 : 13

Taxon classification Animalia Zoantharia Sphenopidae

11. Sphenopus marsupialis (Gmelin, 1791) Figures 10A, B, 11

Specimens examined

(n=2). RMNH Coel 40506, East Kalimantan–Berau Expedition station BER.14, lighthouse northeast side of Pulau Panjang, Berau Islands, East Kalimantan (02°23'14"N, 118°12'34"E), depth = 12 m, collected on October 09, 2003 by B.W. Hoeksema; RMNH Coel 40509, East Kalimantan–Berau Expedition station BER.01, east side of Pulau Derawan, Berau Islands, East Kalimantan (02°17'32"N, 118°15'43"E), depth = 14 m, collected on October 11, 2003 by B.W. Hoeksema.

Photographic records

(n=7). west Pulau Barang Caddi, Spermonde Archipelago, South Sulawesi (05°05'08"S, 119°18'55"E), October 06, 1997; east Bone Lola shoal, Spermonde Archipelago, South Sulawesi (05°03'15"S, 119°21'30"E), October 27, 1997; east Pulau Kudingareng Keke, Spermonde Archipelago, South Sulawesi (05°06'15"S, 119°17'35"E), September 17, 1997; north Pulau Kudingareng Keke, Spermonde Archipelago, South Sulawesi (05°06'07"S, 119°17'15"E), October 1, 1997; station BER.01, east Pulau Derawan, East Kalimantan, Berau Islands (02°17'32"N, 118°15'43"E), October 11, 2003; station BER.14, lighthouse northeast Pulau Panjang Island, East Kalimantan, Berau Islands (02°23'14"N, 118°12'34"E), October 9, 2003; station BER.24, southeast Pulau Samama, East Kalimantan, Berau Islands (02°07'51"N, 118°20'23"E), October 15, 2003.

Description.

The type species of the azooxanthellate genus Sphenopus , this species has an Indo-West Pacific distribution ( Reimer et al. 2012b). Uniquely for the order, species in this genus are unitary (not colonial), and usually free-living, as they are not attached to substrate, and instead embedded in sand or loose gravel/substrate (Figures 10A, B). Individuals can often grow to large sizes (for zoantharians); up to several cm in both length and polyp diameter. Taxonomic examination of this genus is quite limited, with only two recent studies ( Soong et al. 1999, Reimer et al. 2012b), both of which clearly state that further research is needed to more clearly understand this group.

Specimen RMNH Coel 40506 consists of seven polyps, with an average height of 24.4 mm (range 18.5 to 30 mm), and an average width of 8.4 mm (range 6 to 11 mm). The non-peduncle portions of the polyps are 15-20 mm in height, with the remainder made up of peduncle.

Specimen RMNH Coel 40506 has some polyps (five of seven) somewhat different in morphology from RMNH Coel 40509 and other Naturalis Sphenopus marsupialis specimens from the Indian Ocean. These polyps have regularly spaced small round “tubercles” (approx. 1 mm in diameter) on the upper half of their scapus arranged in vertical lines (n=8-14 vertical tubercle lines on each polyp, with 6-10 tubercles per line), making this portion of the polyp appear furrowed. As well, polyps have a small, stubby “peduncle” (2 to 5 mm in width) that is not attached to any hard substrate, intermediate between Sphenopus marsupialis with its completely rounded bottom end and Sphenopus pedunculatus with its long, attached peduncle. For now, we identify these specimens as Sphenopus marsupialis as their peduncles were not attached to the substrate, but it is clear more examination of these specimens is needed.

Specimen RMNH Coel 40509 consists of two polyps of different sizes, with the smaller one being 16 by 5 mm, and the larger one 24 by 15 mm. Both polyps have no peduncle and are tapered. Both polyps are somewhat rugged on their outer surface, with no discernable tubercles, and have intermittent (=not one clear stripe) small darker vertical patterns in between the capitulary ridges only on the top 3-5 mm of the oral end of polyps.

Distribution.

Regions recorded in this study (Figure 11). Spermonde Archipelago (9), Berau Islands (19).

Previous records. This species has been reported from many locations in the Indo-West Pacific, including Taiwan ( Soong et al. 1999) and Brunei Darussalam ( Reimer et al. 2012b).

Remarks.

Specimen RMNH Coel 40506 may be similar to a putative undescribed Sphenopus species mentioned in Soong et al. (1999) from Taiwan based on its smaller size.