Anseropoda rosacea ( Lamarck 1816 )

Yiu, Sam King Fung & Mah, Christopher L., 2024, New Ecological Observations and Occurrence for Asteroidea and Echinoidea in Hong Kong, Zootaxa 5526 (1), pp. 1-69 : 37-39

Anseropoda rosacea ( Lamarck 1816)

FIGURE 27A–E

Comments

Anseropoda rosacea is a distinctive species recognizable by its 14–17, mostly 14–16 arms and the extreme dorsoventrally flattened body, which approximates the thickness of cloth fabric. Prior accounts of this species from Liao & Clark (1995) and Marsh & Fromont (2020) have recorded specimens ranging in R to 11.0 cm and 13.0 cm respectively. Specimens collected and observed herein agree in size range but differ in displaying up to 17 arms ( Fig. 27A–D ).

In Australia this species is described as having a gray abactinal surface with black speckling or mottled orangepink with a white actinal surface with gray or rust along the tube foot grooves (H.L. Clark 1946, Marsh & Fromont 2020). The Hong Kong specimens also displayed a gray abactinal surface with black speckling with some individuals showing a more uniform orange color and a white actinal surface with orange tube feet.

This species has been widely reported from throughout its range ( Koehler 1910, H.L. Clark 1946). H.L. Clark (1946) stated that this species lived in the subsurface of sandy bottoms away from the low tide mark.

Although recorded from southern China ( Liao & Clark 1995), this represents the first occurrence of this species from Hong Kong at a relatively shallow depth. Prior occurrence of this species in China were apparently made from dredges in 110–114 m and fish market collections of unknown depth and locality. Its depth has permitted direct observations, allowing the first known in situ video of this species in Hong Kong.

An unidentified snail, possibly a eulimid were observed attached to the actinal surface of one individual ( Fig. 27E ). Igei et al. (2014) described a species of Paramegadenus in a similar position, the actinal surface, on Anseropoda rosacea from Okinawa. This is possibly the same species.

Time Lapse Video & In situ observation

Aquarium and short time lapse videos of the Hong Kong individuals showed it moving around the aquarium and using the edges of its flattened body surface to cover itself with aquarium gravel. In situ observations of this species are consistent with the behavior, suggesting the coverage with pebbles may serve as protection or camouflage. Its movement pattern over the sediment suggests that it may extend its stomach onto the substratum and feed food on the bottom. Marsh & Fromont (2020) reported this species from the subsurface of sandy bottoms in Australia and have reported this species as having fed on small echinoderms, crustaceans and mollusks, describing it as a scavenger which is sometimes taken in rock lobster pots.

In situ observations of this species ( Fig. 27A ) showed this species lying nearly flush on a gray sandy/muddy bottom with small coarse stones. The speckled color of this species appears similar in appearance to the sediment on which the animal was observed.

Occurrence/Distribution

Hong Kong, 7–20 m.

Outside Hong Kong. Hainan Island, Southern China, Taiwan, Okinawa, Japan, Indonesia, southwest coast of Western Australia, northern Australia to southern Queensland and off the east coast of Tasmania, Bay of Bengal , 0–145 m.

Figures

FIGURE 27. Anseropoda rosacea A. In situ view of abactinal surface. B–C. Abactinal view of individuals showing color variation. D. Actinal views showing color variation. E. Snail attached to the actinal surface of the specimen. Photographer: Sam King Fung Yiu.