Aciconula australiensis Guerra-Garcia 2004

Length: 2.1mm; Head with small projection; pereonite 2 with an acute projection medially. Pereonite 3 and 4 subequal. Pereonites 5 - 7 decreasing in length respectively. Gills on pereonites 3-4, oval. Antenna 1 about 2/5 of body length; proximal article of the peduncle with a setose hump proximally; distal article of peduncle short. Antenna 2 about a half of antenna 1; swimming setae absent; proximal article with a distal projection; flagellum two-articulate. Gnathopod 1 basis as long as ischium, merus and carpus combined; propodus elongate, length about 2 times width, palm with a pair of grasping spines. Gnathopod 2 inserted on the anterior half of pereonite 2; basis ¾ as long as pereonite 2; ischium rectangular; merus rounded; carpus triangular; propodus shorter than basis, palm carrying a large projection proximally provided with a robust grasping spine. Pereopods 3 and 4 reduced about half of the gills length, two-articulate; basal article rectangular with one setae; distal triangular with two simple setae and a plumose one. Pereopod 5, six-articulate, elongate and provided with long setae; distal article small reduced to a small cone carrying one setae apically. Pereopods 6 and 7 described from the female allotype, subequal, setose, palm of propodus carrying a pair of grasping spines. Penes rounded, as long as wide, with a cleft distally. Abdomen with a pair of lateral lobes and a single dorsal lobe; lateral lobes with groups of setae, four in the proximal half and three in the distal half; dorsal lobe carrying a pair of plumose setae (setae are degenerated abdominal appendages). Females: projection on head lacking; gnathopod 2 without proximal projection; pereopod 3 four-articulate (instead of two-articulate in male’s); distal article reduced to a small cone provided with a plumose seta; öostegites on pereonite 3 and 4 with setae; abdomen with 2 pairs of setae (no appendages).

Western Australia; Great Barrier Reef

Named for location of first description (Australia)

Caprellid, "Ghost" or "Skeleton" shrimp, so called for their skeletal appearance. Amphipod crustaceans, easily distinguished by the elongate stick-like body form and reduction of the abdominal appendages. Head is generally fused with pereonite 1. Pereopods on first 2 segments (pereonites) are most flexible and called gnathopods; gnathopods 2 being the largest, used in defense, feeding and substrate attachment. In many species pereopods 3 and 4 may also be reduced or absent. Gills on pereonites 3 + 4, rarely on pereonite 2. Pereopods 5 - 7 much smaller than 1 + 2, used for clinging to the substratum. In females, brood plates öostegites) develop on pereonites 3 + 4. Much remains to be learnt about their biology, ecology and in many cases changing distributions.

Attached to coral with encrusting bivalve mollusks, small hydroids and algal turf associated to dead coral

Females differ from A. miranda in that distal (fourth) article of pereopod 3 is well-developed (tiny in A. miranda). Also, inner lobes of the lower lip are bi-lobed in A. australiensis whereas they are simple (not bi-lobed) in A. miranda.

Australian Museum, Sydney: AM P62148; AM P62149; AM P61735; AM P61736

Littoral (0 to 30 m), 12 m.

Marine, clinging to small hydroids or algal turf on dead corals.