Australian Amphipoda: Leucothoidae

J.K. Lowry, P.B. Berents and R.T. Springthorpe
Division of Invertebrate Zoology
The Australian Museum
6 College Street, Sydney, NSW 2010, Australia
Phone: 612 9320 6260
Fax: 612 9320 6050

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The two important works on Australian leucothoid amphipods are Barnard (1972) and Thomas (1997) There are currently 15 species of Leucothoidae described from Australian waters: 8 Leucothoe, 4 Anamixis, 2 Paraleucothoe, and 1 Leucothoella. The genera Paraleucothoe and Leucothoella appear to be Australian endemics.

The majority of species (13) are known from south-eastern Australia, but five species are known from the south, four from the south-western, four from the north-western, two from the north and five from the north-eastern area. All Australian species except, L. commensalis and P. novaehollandiae, are currently considered to be endemic. Krapp-Schickel (1989) reported 10 species of Leucothoe from the Mediterranean with three endemics. Ledoyer (1986) reported 17 species in three genera from Madagascar with only five endemics. A number of these species have Indo West Pacific distributions.

We cannot predict how many leucothoids are living in the bays and the continental shelves of Australia, but the fauna should at least double when the northern species are known. We think that the leucothoid fauna of south-eastern Australia is relatively well known, but users, particularly of the interactive key, should be aware that the possibility of unreported taxa appearing in samples, particularly from areas outside of south-eastern Australia, is high.

Leucothoid amphipods are mainly associated with tunicates and sponges. In Australian waters P. novaehollandiae is almost always found in the salked tunicate Pyura spinifera. Leucothoe is found in a variety of sponges and tunicates.

Taxonomic Changes

When Thomas & Barnard (1983) announced the transformation of males of Leucothoides pottsi (Leucothoidae, Dana, 1852b) into males of Anamixis hanseni (Anamixidae Stebbing, 1897) they avoided synonymising the families because this was "simply an announcement of a discovery and current research indicates many species and patterns of behaviour remain to be described". In the intervening period more species in both families have been described and still they remain separate (Barnard & Karaman, 1991).

In this monograph the Anamixidae are considered to be synonymous with the Leucothoidae. Females and developing males are known as "leucomorphs" and were originally known in the leucothoid genus Leucothoides. But in one moult developing males are transformed into an "anamorph" stage which has always been known in the genera Anamixis, Paranamixis or Nepanamixis. Some Leucothoides species have been identified with anamixid males, in which case their name (genus and/or species) changes, but others have not and remain as Leucothoides. Once identified with an "anamorph" these females and developing males are considered to be anamixids, but in fact they cannot be distinguished from leucothoids. The "anamorph" is just a specialised reproductive male. There are similar cases in other parts of the Amphipoda such as the lysianassid and phoxocephalid amphipods where the adult male looks very different to females and developing males. For instance, in the lysianassid species Acontiostoma marionis females and primary males look alike (Lowry & Stoddart, 1986). In about 4% of the population, secondary males develop which do not have mouthparts, but do have male secondary sexual characters such as a well developed callynophore and pappose setae on uropods 3. These secondary males differs as much from females and primary males as anamixid males differs from female Leucothoides. We see no logical reason for the Anamixidae to remain as a separate family and synonymise it here with the Leucothoidae.

In the current literature (Barnard & Karaman, 1991) Leucothoella is considered to by a subgenus of Leucothoe. In this study we re-establish Leucothoella because of the unique morphology of coxa 2 and the unique slightly expanded bases of peraeopods 5 to 7.

J.L. Barnard (1972: 262) considered P. flindersi (Stebbing, 1888) to be a distinct species, but in Barnard & Karaman, 1991, Paraleucothoe is considered to contain one species P. Novaehollandiae. There are a number of morphological differences between P. novaehollandiae and P. flindersi which indicates that they are separate species.

This study is based on collections held in the Australian Museum: AM; the Natural History Museum, London (BMNH); the Museum of Victoria: NMV; and the Western Australian Museum: WAM.

The following abbreviations are used on the plates: A, antenna; C, coxa; E, epistome; EP, epimeron; G, gnathopod; H, head; MD, mandible; MP, maxilliped; MX, maxilla; OP, outer plate; P, peraeopod; p, palp; T, telson; U, uropod; UR, urosomite.

This publication should be cited as : Lowry, J.K., P.B. Berents & R.T. Springthorpe, 2000. Australian Amphipoda: Leucothoidae. Version 1: 2 October 2000.