Rhinopias aphanes


Rhinopias aphanes, the lacy scorpionfish, weedy scorpionfish or Merlet's scorpionfish, is a species of marine ray-finned fish belonging to the family Scorpaenidae, the scorpionfishes. This species is found in the Western Pacific. It occasionally makes its way into the aquarium trade.

Taxonomy

Rhinopias aphanes was first formally described in 1973 by the American ichthyologist William N. Eschmeyer with the type locality given as New Caledonia. The specific name aphanes means "that which is unseen or inconspicuous", an allusion to the camouflage created by its notable coloration and flaps of skin.

Description

Rhinopias aphanes has two black spots in the middle of the membrane between the sixth and eighth rays of the dorsal fin, while R. argoliba, R. cea and R. xenops all lack them. Therefore, this feature allows us to distinguish this species from its relatives; other differences include the lack of scales on the operculum between the tips of the upper and lower opercular spines and the opercular margin, and it having only 16 or 17 pectoral-fin rays. It can be distinguished from the other two species in the genus - namely R. eschmeyeri and R. frondosa - by noticing its non-fleshy membranes on the spiny part of the dorsal fin and clearly notched margins of the soft-rayed portions of all but its pectoral fins. Additionally,
  1. In this species, the tips of each caudal fin ray have two branches in adults, while in the other two species there are four.
  2. The dorsal fin spines are rigid with strongly pointed tips; in R. eschmeyeri and R. frondosa the fins are relatively soft, with easily bended tips.
  3. The lateral lacrimal spine is pointed; in the other two species it may be absent or vestigial.
  4. The suborbital ridge typically has three pointed spines instead of three bumps.
This species has 12–18 tentacles underneath the lower jaw, 2-4 tentacles below the eyes and many tentacles on the flanks above the lateral line. There are also clearly branched, long tentacles on the supraocular and rear lacrimal spines. This species can grow to a total length of.

Distribution and habitat

Rhinopias aphanes occurs in the western Pacific where it has been recorded from Queensland, Papua New Guinea, New Caledonia, and Vanuatu. It is found at depths between. This is a rare species found on coral slope and soft substrates. It is a benthic fish, which rests on the seabed.

Biology

Rhinopias aphanes is very reluctant to leave the seafloor, and normally just lies on the bottom and rocks gently back and forth and from side to side. Rather than swimming, this species moves around by "walking" and "hopping", which are powered by the pelvic and pectoral fins. It expels water through branchial tubes above the operculum, making the tentacles present on the first few soft rays of the dorsal fin quiver; since this bears resemblance to the swaying movements of algae or benthic invertebrates in the current, it improves the camouflage of this fish and thus its chances of ambushing smaller fish. Rhinopias aphanes is more active during the night.

Utilisation

Rhinopias aphanes is a much sought after fish in the aquarium trade.