A PRELIMINARY STUDY ON THE PHYLOGENY OF PONTONIINAE (DECAPODA: PALAEMONIDAE)
Li Xinzheng; Liu Ruiyu (J. Y. Liu)(Institute of Oceanology Chinese Academy of Sciences, Qingdao 266071)
In recent years, many new genera were established in the subfamilypontoniinae, palaemonidae. In order to approach the position of these genera and thesystematic relationships among the genera of the subfamily, a preliminary phylogeneticanalysis using cladistics was made in the present paper 80 morphologicalcharateristics were analysed and 165 characteristic states, including 85 apomorphicconditions, were determined, based on a comparative morphological study andcharasteristic analysis of 72 genera of all the 75 genera (Climeniperaeus, Exoclimenellaand Periclimenella are not included in this study) of this subfamily. 17 of the 72genera, i.e., Anchistus, Conchodytes, Coralliocaris, Dasycaris, Epipontonia, Eupontonia,Harpiliopsis, Ischnopontonia, Jocaste, Onycocaridites, Onycocaris, Palaemonella,Periclimenaeus, periclimenes [including the two subgenera, periclimenes (s. str.) andHarpilius], Philarius, Pontonia, Stegopontonia, were studied in detail. 73 OTUs(operational taxonomic units) were identified: every studied genus was regarded as oneOTU except periclimenes, for which, the two subgenera, Periclimenes (s. str.) andHarpilius, were regarded as one OTU respectively- palaemoninae, the. other subfamilyof palaemonidas, was selected as the outgroup for the character analysis. Thedetermined apomorphic conditions (see Tab. 1) are mainly from the following espects: 1)variations of the mouthparts (including the mandible, maxilla, maxillipeds andepistome); 2) variations of the apical part of pereiopods; 3) variations on the carapace,such as the spines fewer and the sdse sculptured, 4) body form, such as thevariations from more or less compressed lateraly to compressed strongly or, todepressed dorsoventally, 5) associations with other invertebrates, 6) distributions; 7)variations of rostrum and antenna; 8) variations on the tail fan. According to theapomorphic conditions outlined in Tab. 1, the distributions of the charateristic states ofthe 73 OTUs are shown in Tab. 2. The analysis was carried out with Hennig 86program (version 1.5) to obtain a cladogrm of the phylogenetic relationships amongthe 73 OTUs (Fig. 1). The cladogram shows that the Pontoniinae is a typicmonophyletic group, bu the systematic position of some genera proposed in recentyears, particulary the monotypic ones, needs furthr study. In accordance with thecladogram, we suppose that: (1) the ancestor of Pontoniinae is a free-livingpalaemonid shrimp, like the existing primitive group of subfamily Palaemoninae, andto avoid predator, some eary groups hide in the pore spases formed by scleractiniancorals and adapte to this environments, and by diversifying natural selections andmultiple differentiation, gradually some groups are associated with certain coelentetalhosts, while other groups adapted to some extent to hosts such as echinoderms,sponges, bivalve mollusks, (2) the genus Periclimenes represents a link between thefree-living groups and those associated with other invedebrates; (3) it appears thegenera associated with sponges and bivalves are more advanced in the evolutionarytrunk than the free-living groups and those associated with coelenterates andechinoderms; and (4) the original zoogeographical cenbe of this subfamily must havebeen located in some cora reef areas of the tropic Indo-West pacific waters. Thehypothetical pattern of evolutionary ttends of pontoniinae groups adapting to their hostsis shown in Fig.2.
【CateGory Index】： Q959
【CateGory Index】： Q959