Calliaster aquamontis
Sea star from New Caledonian seamounts with distinct spine patterns.
Calliaster aquamontis belongs to the sea star family Goniasteridae and lives in waters near New Caledonia. The name *aquamontis* comes from Latin, meaning "water mountain."
For a time, scientists mistakenly identified specimens of this species as *Milteliphaster wanganellensis*. It can be told apart from the New Zealand species *Calliaster wanganellensis* by several features: it has far fewer spines on both the upper and lower marginal plates (just one or two arising from a single point, rather than two separate rows), fewer spines on the upper surface of the disk and arms, an unclear series of carinal plates, and the outermost upper marginal plates meet at the arm tip (which they do not in *C. wanganellensis*). It also resembles *Calliaster spinosus* from southern Australia, especially in having seven to eight furrow spines, but differs in having indistinct carinal plates, upper marginal plates that meet two to five pairs from the arm tip, and larger marginal plates (19 to 30 per interradius at an arm length of 7.8 cm, compared with 50 to 52 in *C. spinosus* at 14.0 cm). Another similar species is *Calliaster chaos* from the Indian Ocean; both have spines mostly on the disk and meeting upper marginal plates near the arm tip, but *C. aquamontis* has fewer furrow spines (six to seven versus nine to ten) and a less crowded arrangement of spines on the upper surface.
The body is star-shaped, with arms that are short and triangular. The ratio of arm length to disk radius ranges from 2.4 to 3.2. Spines appear on the plates near the center of the disk and in each space between the arms, but not on the outer plates that touch the upper marginal plates. There are 19 to 30 upper marginal plates per interradius (from one arm tip to the next), making up about 14 to 15 percent of the disk diameter. These upper marginal plates carry two rows of prominent, pointed, conical spines. Each actinal plate has one large, obvious spine, and the rest of the plate is bare and smooth; about a quarter of these plates also have a paddle-shaped pedicellaria next to the spine. The number of furrow spines is six or seven. There are two subambulacral spines, which may be bluntly conical or flattened with chisel-like tips.
This sea star is found on seamounts off New Caledonia, at depths between 425 and 540 meters.
Quick Facts
- Genus
- Calliaster
- Species
- aquamontis
Facts from the source article.
Lore & Background
Specimens of Calliaster aquamontis were previously misidentified as Milteliphaster wanganellensis. It is distinguished from the New Zealand species Calliaster wanganellensis by having significantly fewer superomarginal and inferomarginal spines (1 or 2 from a single point versus 2 different series), fewer abactinal spines on the disk and arms, an indistinct carinal plate series, and distalmost abutting supermarginal plates (absent in C. wanganellensis). It also shares some similarities with Calliaster spinosus from southern Australian waters, such as similar numbers of furrow spines (7–8), but differs by having indiscrete carinal plates, abutted superomarginal plates 2–5 pairs from the arm tip, and larger marginal plates (19–30 per interradius at R=7.8 cm vs. 50–52 in C. spinosus at R=14.0 cm). It shows resemblance to the Indian Ocean species Calliaster chaos, sharing abactinal spines predominantly on the disk and abutted superomarginal plates distally, but differs by having fewer furrow spines (6–7 vs. 9–10 in C. chaos) and a less dense arrangement of abactinal spines.
Reader's Guide
Calliaster aquamontis is notable for its distinct morphology among Goniasteridae sea stars, particularly its spine arrangement and plate counts that differentiate it from related species in New Zealand, Australia, and the Indian Ocean. The species was originally confused with Milteliphaster wanganellensis, highlighting the taxonomic challenges in this group. Its description provides key comparative data for understanding regional variation in Calliaster, especially regarding superomarginal plate numbers and furrow spine counts. The species is known exclusively from seamounts off New Caledonia at depths of 425 to 540 meters, emphasizing its deep-water habitat. The presence of paddle-shaped pedicellariae on about 25% of actinal plates is a distinctive feature. The species epithet 'aquamontis' (water mountain) references its seamount environment. Its short, triangular arms and stellate body with a specific arm-to-disk ratio further characterize this deep-sea starfish.
Did You Know?
- The species epithet aquamontis is Latin for 'water mountain'.
- It has 6–7 furrow spines, fewer than the 9–10 found in Calliaster chaos.
Frequently Asked Questions
What is Calliaster aquamontis?
It is a deep-sea starfish in the family Goniasteridae, native to the waters surrounding New Caledonia. The species epithet 'aquamontis' is Latin for 'water mountain,' a reference to the seamount habitats where it is found.
At what depth does Calliaster aquamontis live?
This starfish is restricted to a fairly narrow band between roughly 425 and 540 meters below the surface. It is typically encountered on the rocky slopes of New Caledonian seamounts rather than on open abyssal plains.
How do you tell Calliaster aquamontis apart from Calliaster wanganellensis?
The New Caledonian species carries far fewer spines on its upper and lower marginal plates, with only one or two arising from a single point instead of two distinct rows. It also has a sparser arrangement of spines across the disk and arm surfaces compared to its New Zealand relative.
Was Calliaster aquamontis ever confused with another species?
Yes; for a period, specimens of this starfish were misidentified as Milteliphaster wanganellensis before being correctly reclassified. The confusion was eventually resolved by examining spine counts and plate arrangements that differ between the two.
What are the key physical measurements of Calliaster aquamontis?
Its short, triangular arms span about 2.4 to 3.2 times the disk radius, and each interradius bears 19 to 30 superomarginal plates. The oral furrow region carries 6 to 7 spines while the subambulacral area has just 2, giving the animal a noticeably sparser overall appearance.
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