Cambaroides

Abstract: The phylogenetic position of the four East Asian freshwater crayfish species of the genus Cambaroides is not settled. Morphological phylogenetic analyses suggest close affinities of Cambaroides with North American Cambaridae. This view is based mainly on characters of the male and female reproductive organs. In contrast, the only molecular phylogenetic analysis so far available leaves the phylogenetic position of Cambaroides unresolved. The question of whether Cambaroides is monophyletic or paraphyletic has so far been neither addressed morphologically nor with molecular data sets. Here we present the first comprehensive phylogenetic analysis of all four currently described species of Cambaroides in the framework of Northern Hemisphere freshwater crayfish (Astacoidea) relationships based on partial sequences of two mitochondrial genes (CO1 and 12S rRNA). Despite some evidence in favour of a monophyletic Cambaroides more data is needed to resolve this question. Our analyses suggest a close relationship of the North American Cambaridae and the European Astacidae, leaving the Asian Cambaroides basal to them. If these results hold true the similar reproductive organs of Cambaroides and American Cambaridae must be either homoplastic or ancestral for Northern Hemisphere Astacoidea. Zusammenfassung Die phylogenetische Beziehung der vier ostasiatischen Flusskrebsarten der Gattung Cambaroides in Relation zu den anderen Taxa der Astacoidea ist weitgehend unbestimmt. Phylogenetische Analysen morphologischer Merkmale der Reproduktionsorgane unterstutzen eine nahe Verwandtschaft von Cambaroides und den in Nordamerika lebenden Vertretern der Cambaridae. Bislang existierende molekulare Ergebnisse konnen dieses Ergebnis nicht stutzen, lassen aber die Fragen der Monophylie und der phylogenetischen Position von Cambaroides innerhalb der Astacoidea unbeantwortet. Diese Arbeit zeigt die erste umfassende phylogenetische Analyse aller vier beschriebenen rezenten Spezies der Gattung Cambaroides und ihrer phylogenetischen Beziehung innerhalb der Astacoidea, anhand zweier mitochondrialer Genabschnitte (12S rRNA und CO1). Unsere Analyse zeigt die nahe Verwandtschaft der nordamerikanischen Cambaridae und der europaischen Astacidae, wahrend Cambaroides basal zu dieser Gruppierung steht. Dieses Ergebnis lasst den Schluss zu, dass die ahnlichen Reproduktionsorgane von Cambaroides und den amerikanischen Cambaridae entweder plesiomorph fur die Astacoidea oder konvergent sind.

Abstract: Little is known about the biology of the East Asian freshwater crayfish of the genus Cambaroides. Furthermore, the phylogenetic relationships of Cambaroides are controversial. To gain more information about East Asian crayfish and to shed some light on the phylogeny and evolution of freshwater crayfish, some aspects of the embryonic and postembryonic development of the Japanese freshwater crayfish species Cambaroides japonicus are described. The general appearance of the embryo and the growth zone consisting of about 40 ectoteloblasts correspond with the apomorphic pattern described for all other freshwater crayfish species. The occurrence of eight mesoteloblasts is a typical malacostracan character. In addition to the occurrence of freshwater crayfish apomorphies, such as a telson thread, the postembryonic development of C. japonicus follows the ground pattern of the Northern Hemisphere Astacoidea. In particular, some characteristics are in common with the postembryonic development of the Astacidae. These concern the shape of the telson of the juvenile stage 1 and the occurrence of plumose telson setae in juvenile stage 2. Furthermore, the recurved hooks of the hatchlings are lost in the juvenile stage 2, indicating an early independence of the juveniles from the mother. On the other hand, the early appearance of a spermatheca (annulus ventralis) is shared between C. japonicus and the other (American) Cambaridae. The hypothesis is developed that the evolutionary success of the different freshwater crayfish taxa might be related to the stepwise extension of maternal care as an adaptation to the freshwater environment.

Abstract: The phylogeny of freshwater crayfish is assessed using a morphological analysis of fossil and extant taxa. Based on external morphological characters, primarily characters of the carapace and appendages, the crayfish comprise a monophyletic group (Astacida). The sister taxon to the crayfish is the Chilenophoberidae, a clade of extinct marine lobsters. Synapomorphies of the freshwater crayfish include a distinctive carapace groove pattern and mobility of the last thoracic segment. Within the Astacida, three smaller clades, considered to be family-level groups, are identified and redefined. All parastacid genera except Gramastacus comprise a monophyletic clade. Species in the Cambaridae are characterized by an apomorphous annulus ventralis in the female, and hooks on the ichiopodites on the third pereiopod in the male. Species in the Astacidae are characterized by randomly arranged tubercules on the medial portion of dactyl. The monophyly of the Astacoidea (Cambaridae plus Astacidae) is also supported. The familial affinity of Cambaroides is questioned, and this genus is tentatively reassigned from the Cambaridae to the Astacidae.

Abstract: Eight species of the genera Branchiobdella and Cirrodrilus are reported from the Soviet Far East. Six of them from the Komarovka Stream in the Ussuriiski State Nature Reserve:Branchiobdella cheni (Liu, 1964), B. domina sp.n., Cirrodrilus chosen (Yamaguchi, 1934), C. suzukii (Yamaguchi, 1934), C. pugnax sp.n., and C. fimbriatus sp.n. Branchiobdellidans are abundant in this stream, occurring on the crayfishes Cambaroides dauricus wladiwostokensis as well as in benthic samples. Two from the northern Amur River basin near Khabarovsk: Branchiobdella minuta Pierantoni, 1912, and Cirrodrilus quadritentacularis (Liu, 1984), living on the crayfishes Cambaroides dauricusdauricus and C. schrencki. The genus Cirrodrilus demonstrates several trends of parallel variation on the Asian continent and the Japanese Islands; the more apomorphic genus Branchiobdella seems to be absent in Japan.