Family ICILIIDAE Dana, 1849

Icilius australis

© Copyright R.T. Springthorpe.

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Introduction

The iciliid amphipods are a small monotypic family group endemic to the marine waters of Australia, Borneo and New Caledonia. No taxonomic studies had been published on the group since Stebbing (1910), until a new study by Watson et al. (2004). Iciliids appear to be suspension feeders living almost exclusively on sponges and gorgonaceans (Watson et al. 2004). Laubitz (1979) considered Icilius as part of the Podoceridae because it has a depressed urosome with an elongate urosomite 1. But since then workers (such as Barnard & Karaman (1991)) have retained Icilius as a monotypic family.

Diagnosis

Head longer than deep; rostrum short; eyes round. Body dorsoventrally flattened; smooth or processiferous. Antenna 1 shorter than or subequal to antenna 2; peduncular article 1 subequal to, or longer than article 2; article 2 longer than article 3; article 3 shorter than article 1; primary flagellum 5- or more articulate; callynophore absent. Antenna 2 medium length or long; flagellum longer than peduncle; 5- or more articulate. Mandible incisor dentate; lacinia mobilis present on both sides; molar fully triturating. Maxilla 1 inner plate strongly setose along medial margin. Maxilliped inner plates well developed; outer plates small. Coxae 1–4 longer than broad or as long as broad, overlapping. Gnathopod 1 not sexually dimorphic; subequal to gnathopod 2; simple; coxa subequal to coxa 2; carpus subequal to propodus. Gnathopod 2 not sexually dimorphic; simple; coxa smaller than but not hidden by coxa 3; ischium short; carpus long, subequal to propodus. Pereopod 3 coxa broader than long or as long as broad; carpus shorter than propodus, not produced. Pereopod 4 coxa larger than coxa 3, acuminate ventrally, with well-developed posteroventral lobe; carpus shorter than propodus, not produced. Pereopod 5 shorter than pereopod 6; coxa subequal to coxa 4, without posterior lobe or equilobate; basis linear, without posteroventral lobe; carpus linear. Pereopod 6 shorter than pereopod 7; basis linear. Pereopod 7 longer than pereopod 5; basis linear. Urosome dorsoventrally flattened; urosomite 1 longer or much longer than urosomite 2. Uropods 1–2 apices of rami with robust setae. Uropod 3 biramous; peduncle short, with medial process; rami lanceolate; outer ramus shorter than, subequal to, or longer than peduncle; inner ramus not apically setose. Telson laminar; entire; longer than broad or as long as broad; dorsal robust setae absent; apical robust setae present.

General References

Barnard, J.L. & Karaman, G.S. 1991. The families and genera of marine gammaridean Amphipoda (except marine gammaroids). Records of the Australian Museum, Supplement 13: 1-866

Dana, J.D. 1849. Synopsis of the genera of Gammaracea. American Journal of Science and Arts 2 8: 135-140

Laubitz, D.R. 1979. Phylogenetic relationships of the Podoceridae (Amphipoda, Gammaridea). Bulletin of the Biological Society of Washington 3: 144-152

Stebbing, T.R.R. 1910. Scientific results of the trawling expedition of H.M.C.S. "Thetis" Crustacea Part V. Amphipoda. Memoirs of the Australian Museum 4(12): 567-658, pls 47-60

Watson, M.J., Lowry, J.K. & Steinberg, P.D. 2004. Revision of the Iciliidae (Crustacea: Amphipoda). The Raffles Bulletin of Zoology 52(2): 467-495

History of changes