Crustacean Research

Phylogenetic relationships of superfamily Gammaroidea (Amphipoda) and its allies from Japan

Ko Tomikawa, Norio Kobayashi, Shunsuke F. Mawatari

Article type: Article
2010 Volume 39 Pages 1-10
Published: 2010
Released on J-STAGE: May 15, 2017

DOIhttps://doi.org/10.18353/crustacea.39.0_1

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The current superfamilial classification of suborder Gammaridea, at least of the Japanese members, requires a full reassessment of their phylogenetic relationships. We investigated 17 species representing six families in three superfamilies from Japan, based on partial sequences of the mitochondrial 16S rRNA and nuclear 28S rRNA genes. Members of superfamily Gammaroidea are characterized by having gammarid-type calceolus on their antennae, but our molecular analyses did not support the monophyly of Gammaroidea. The unique gammarid-type calceolus found in Gammaroidea may not be a synapomorphy for this group. Monophyly of the families studied, except for Melitidae, was supported by neighbor-joining, maximum parsimony, and maximum likelihood analyses. The molecular analyses revealed that during their evolutionary history, gammaroidean amphipods repeatedly switched between marine and freshwater habitats.

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Larval development of two Atergatis species (Decapoda, Xanthidae) described from laboratory-reared material

Hironori Tanaka, Toshiro Saruwatari, Takashi Minami

Article type: Article
2010 Volume 39 Pages 11-35
Published: 2010
Released on J-STAGE: May 15, 2017

DOIhttps://doi.org/10.18353/crustacea.39.0_11

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The four zoeal stages and one megalopal stage of Atergatis subdentatus (De Haan, 1835) and Atergatis reticulatus (De Haan, 1835) are described and illustrated, based on laboratory-reared material. The morphological characters of the larvae of these two species are compared with those of six other zosiminid genera (Atergatopsis, Lophozozymus, Platypodia, Platypodiella, Zosimus & Zozymodes) to identify generic diagnostic larval characters.

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Larval stages of the crinoid-associated squat lobster, Allogalathea elegans (Adams & White, 1848) (Decapoda: Anomura: Galatheidae) described from laboratory-reared material

Yoshihisa Fujita

Article type: Article
2010 Volume 39 Pages 37-53
Published: 2010
Released on J-STAGE: May 15, 2017

DOIhttps://doi.org/10.18353/crustacea.39.0_37

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The complete larval development of Allogalathea elegans (Adams & White, 1848) is described and illustrated from laboratory-reared material. This species has four zoeal stages and one megalop. Diagnostic zoeal characters of the genus Allogalathea are compared with those of the other galatheid genera for which the larval morphology is known. Zoeas of A. elegans are readily distinguished from those of other galatheids by the combination of setation of the maxillular and maxillar endopods. Megalopal morphology of A. elegans is remarkably different from those of the two sympatric galatheids, Galathea amboinensis and G. inflata, in dentition on the lateral margins of the rostrum and carapace.

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The larval development of Chirostylus stellaris Osawa, 2007 (Crustacea: Anomura: Chirostylidae) described from laboratory reared material

Yoshihisa Fujita, Paul F. Clark

Article type: Article
2010 Volume 39 Pages 55-66
Published: 2010
Released on J-STAGE: May 15, 2017

DOIhttps://doi.org/10.18353/crustacea.39.0_55

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The complete larval development of the anomuran chirostylid, Chirostylus stellaris Osawa, 2007, is described and illustrated from laboratory-reared material. This species has two zoeal stages and one megalop. The zoeal phase was completed within 48 hours and the megalopl phase lasted approximately three weeks. The setae on the coxal, basial and endopodal segments of the maxillule, maxilla, first maxilliped and second maxilliped were absent in zoeal stages suggesting that they did not feed during this phase. In fact C. stellaris zoeas showed lecithotrophic and abbreviated development. The zoeas of Chirostylus are distinguishable from those of other chirostylid genera such as Gastroptychus, Uroptychus, and Eumunida. However, no significant differences were found among zoeas of three Chirostylus species including C. ortmanni, C. sandyi and C. stellaris.

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Geographical variation in morphological characters of Ilyoplax pusilla (De Haan, 1835) (Brachyura: Dotillidae)

Keiji Wada, Nozomi Yoshihara

Article type: Article
2010 Volume 39 Pages 67-70
Published: 2010
Released on J-STAGE: May 15, 2017

DOIhttps://doi.org/10.18353/crustacea.39.0_67

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Ilyoplax pusilla (De Haan, 1835), a Japanese intertidal mudflat inhabitant, is known to exhibit genetic differentiation between populations from mainland Japan and Ryukyu Islands. Morphological variation of I. pusilla was examined for possible correlations with the genetic population structure. Among adult specimens collected from four mainland and two Ryukyu Islands populations, two morphological types were found in each of three characters, i.e. abdominal telson of both sexes and male first pleopod, among which the variation of the male first pleopod was consistent with their respective population groups, which indicates a relationship between morphological variation and genetic differences.

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[title in Japanese]

Article type: Appendix
2010 Volume 39 Pages 71-
Published: 2010
Released on J-STAGE: May 15, 2017

DOIhttps://doi.org/10.18353/crustacea.39.0_71

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