THE EVOLUTION OF SPINY LOBSTERS (PALINURIDAE): A STUDY OF EVOLUTION IN THE MARINE ENVIRONMENT R. W. GEORGE Western Australian Museum, Beaufort Street, Perth, Western Australia A. R. MAIN Zoology Department, University of Western Australia, Nedlands, Western Australia Received October 18, 1966 The purpose of this paper is to evaluate to assess "significant" characters upon relationships in the light of morphological which to base our phylogenetic arrange­ and paleontological evidence, and to pro­ ment, we first tabulated the major external pose an evolutionary scheme which accounts morphological features which varied most for the present distribution of extant between genera. For some features no palinurid species. The spiny lobsters, be­ meaningful arrangement could be obtained. cause of their large size, commercial im­ For instance, the form of the abdominal portance, benthic habits as adults and sculpturing could be arranged as follows: pelagic habit as larvae, and their wide no sculpture, one transverse groove inter­ geographic and vertical distribution, are rupted medianly, one continuous transverse well suited for a study of evolution in the groove, four transverse grooves, seven marine environment. In 1946 Holthuis transverse grooves. However, other ab­ provided an excellent basic taxonomic re­ dominal sculpture patterns are found which vision of the Palinuridae and, sometimes are not easily fitted to this series, e.g. with colleagues, he followed this up with squamiform sculpture or longitudinal carina. more detailed studies of smaller groups Because of the inconsistency in the trend within the family, particularly in the genus of this feature, and because similar forms Panulirus. But some of the less well known of abdominal sculpture occur in many genera inhabiting deeper waters still require other crustacean groups which are unrelated revision and for this reason it has been to palinurids, and also because the partial necessary to include some taxonomic discus­ trend given above is not supported by the sion in the paper; this has been kept to trends of any of the other features, ab­ a minimum and will be reported on more dominal sculpture is considered to be a fully in an appropriate publication at a random development rather than a phy­ later date. The deficiencies in our knowl­ logenetic indicator. Two other features edge of palinurid systematics and evolu­ were also placed in this category (see p. tion have been realized by Glaessner (1960) 807). who stated (p. 42), "There is still some We were searching for morphological doubt about homologies and evolution in the characters which: (a) could be arrayed in Scyllaridea [Palinuridae and Scyllaridae] order and accommodate all the genera of ... for which groups more morphological the family in each arrangement; (b) were information on recent and fossil forms is consistent with one another in their trends; required." We have attempted to overcome (c) were based on features characteristic these deficiencies and to present speciation of the family and rarely, if at all, found mechanisms applicable to the marine en­ in other crustacean groups; (d) were vironment. judged most likely to have a selective advantage in certain environments. PHYLOGENETIC RELATIONSHIPS Four features examined fulfilled these We have based our phylogenetic scheme requirements but before presenting these entirely on external morphology. In order data (see p. 805) it is essential to present EVOLUTION 21: 803-820. December, 1967 803 804 R. W. GEORGE AND A. R. MAIN TABLE 1. Morphological relationships of living palinurid genera. The parallel trend of the Silentes and Stridentes for the same morphological characters is noteworthy. For the Stridentes genera the shape and armature of the antennular plate has also been included. Distal joints of endopod of female SILENTES STRIDENTES Supra­ Eye second pleopod orbital posi­ Antennular Carapace process tion Penultimate Ultimate plate Cylindrical strong elevated full absent PANULIRUS broad, 2-4 vertical expansion large spines Cylindrical strong elevated full vestigial JASUS JUSTITIA triangular, almost expansion PALINURUS unarmed vertical Subcylindrical moderate horizontal moderate reduced PROJASUS PALINUSTUS triangular, slightly expansion unarmed elevated Subcylindrical small horizontal slight large LlNUPARUS narrow, flattened expansion PUERULUS unarmed a brief taxonomic statement on the genera shows that the two lines were present at of the family and to point out that the an early stage of palinurid development. presence or absence of a stridulating ap­ These structures have been described and paratus is regarded by us as indicating a illustrated by George and Grindley (1964) major divergence within the family. The who support the long-neglected proposal stridulating apparatus is formed by a of Parker (1884) to use "Silentes" for the lateral and anterior expansion of the anten­ non-stridulating group and "Stridentes" for nular segment, a dislocation of the interior the stridulating group. margin of the first free antennal joint from this segment, and a latero-internal expan­ PALINURID GENERA sion of the first free antennal segment. Holthuis (1946) listed eight genera in This expanded stridulating pad of the the family Palinuridae and since that time antenna is ribbed ventrally and when the one additional genus, Projasus George and antenna is moved, it rubs across a polished Grindley 1964, has been described. How­ ridge on the lateral margin of the anten­ ever we are of the opinion that Palinurellus, nular segment. Those genera which do one of the genera mentioned by Holthuis, not have the ability to stridulate have a should be removed from the palinurid list narrow, vertical antennular plate, the since it has obvious affinities with the antero-external margin of which serves as Scyllaridae and Polychelidae as well as the fixed articulation point of the antenna. with the Palinuridae. These affinities have The possession of a stridulating ap­ been discussed at length by de Man (1881, paratus is well known to be an advantage 1882), Bate (1881), and Boas (1882). to the species for warning (and probably After examination of male specimens from recognition and mating, as well) purposes Florida, we support their conclusions which and we consider it most unlikely that dis­ may be summarized by the statement of location and relocation of the antenna to Bate (1881:226) "The eyes are those of the antennular plate has occurred more the Scyllaridae; the second pair of antennae than once in the history of the family. are those of the Palinuridae. The legs are Our conclusion that the development of a common to both forms, and the carapace "stridulating line" from a nonstridulating belongs to neither. The frontal region stock is also supported by palaeontological resembles neither; and the posterior re­ evidence (given later in this paper) which sembles both, as also does the pleon, EVOLUTION OF SPINY LOBSTERS 805 whereas the pleopoda are modelled on the Palaeopalinurus Bachmeyer, 1954. Jurassic. type of those of the Scyllaridae, and the Palinustus A. Milne-Edwards, 1880. Three (pos­ sibly four) extant species in East Indies, off tail fan is that of both." We agree with East Africa, Japan, and West Indies. Bate and de Man that Palinurellus should Astacodes Bell, 1863. Lower Cretaceous of Europe. be placed in a separate family, the Syn- Justitia Holthuis, 1946. Accepting Gordon's axidae. Nevertheless, Palinurellus assumes (1960) broad concept to include Nupalirus Kubo, 1955, three named (possibly five involved special significance since several workers actually) extant species off Mauritius (two have acknowledged its primitiveness (e.g., spp.), Japan, Hawaii, and West Indies. Boas, 1882) and its morphological affinities Palinurus Fabricius, 1798. Four extant species, with fossil genera (Winkler, 1882). three in the east Atlantic, and one off East Africa. This genus has had many fossil species The review by Holthuis (1946) provides included in it but a critical examination of basic distributional data for the species them has not been attempted. of Palinuridae. This has been brought up PanuUrus White, 1847. Nineteen species in the to date by reference to unpublished data tropic and subtropic waters of the Indian, (R.W.G.) and to publications after Holthuis Pacific, and Atlantic Oceans. (1946). These include Anon (1964), Bar­ nard (1950), Bruce (1965), Edmondson Incertae Sedis (1951), Forest and Postel (1964), George Cancrinus Munster, 1839. This Liassic genus is (1962), George and Grindley (1964), regarded as intermediate between the palinurids and the scyllarids because of the club-shaped George and Holthuis (1965), Gordon antenna. (1960), Holthuis (1954, 1961, and 1963), Palinurina Munster, 1839. Liassic of Europe. Holthuis and Villalobos (1962), Holthuis Eurycarpus Schluter, 1868. Upper Cretaceous of and Zaneveld (1958), Holthuis and Loesch Germany. (1967) and Kubo (1955, 1963). The de­ scriptions given by Woods (1931) have Characters indicating phylogenetic trend. served as a basis for the fossil genera with —After separation into Silentes and Stri­ reference also to Glaessner (1960) and dentes, the extant genera have been ar­ Piveteau (1953). An estimate of the num­ ranged (Table 1) according to the degree ber of fossil species in each genus is not of development of the following four mor­ attempted here. In the Palinuridae, there phological features: (a) the relative size are eight extant and six fossil genera rec­ and disposition of the supraorbital proc­ ognized