Developmental stages of some New Zealand Majidae (Crustacea, Decapoda, Brachyura) with observations on the larval affinities of the Majidae

Abstract

Developmental stages of eight species of the New Zealand Majidae are studied. Detailed descriptions are given of the following larval stages of each species: the pre-zoea, zoea and megalopa stages of Eurynolambrus australis H. Milne Edwards and Lucas (subfamily Pisinae), Notomithrax peronii (H. Milne Edwards), N. ursus (Herbst) and N. minor (Filhol) (Majinae); the pre-zoea and first and second zoea stages of Leptomithrax longipes Thomson (Majinae) and Jacquinotia edwardsii (Jacquinot) (Mithracinae); the pre-zoea and first zoea stage of Leptomithrax longimanus Miers (Majinae). First and second zoea stages of an unknown species, provisionally named Species A are described in detail. The larval stages of each species are compared. The zoea stages of E. australis, N. peronii, N. ursus and L. longimanus are very similar and few characters are available to distinguish between them. A number of minor morphological characters are examined for their usefulness in distinguishing between the zoeas of different species. Tables are provided listing characters which distinguish between and identify, the first zoea stages and megalopas described. Major morphological characters of the zoea and megalopa larvae of the Majidae are discussed. Particular attention is given to the usefulness of pigmentation and to the megalopa carapace as distinguishing characters. Affinities of the larval stages described, are assessed. The larvae of each species are compared with other known larvae of their subfamily. Particular emphasis is given to the Majinae in this respect. (The classification used is that of Garth, 1958). The position of Eurynolambrus australis in the Majidae is confirmed by the characteristics of the larval stages. Larval characters suggest E. australis is more closely related to majine species of the genera Notomithrax and Leptomithrax than to species of the Pisinae. The zoea stages of N. minor are characterised by a number of unusually long spines. It is considered these have no particular phylogenetic significance. Larval characters do not support the positions of Leptomithrax longipes in the same genus as L. longimanus.