Morphology-based phylogenetic studies of the lanternfishes (family Myctophidae) are reviewed the synapomorphies used to define traditionally-recog-nized subfamilies and tribes being surveyed. Re-analyses of 63 previously-re-ported characters indicated monophyly of the following taxa supported by unambiguous synapomorphies: subfamilies Myctophinae and Lampanyctinae and tribes Gymnoscopelini and Gonichthyini. Other tribes either failed to form clades (Myctophini, Electronini, Lampanyctini) or did so, but without the support by unambiguous synapomorphies (Diaphini). For evaluation of the monophyly of these clades, the following aspects are important: (1) character survey at species' level; and (2) assessment of homologies at the species' level between myctophids and neoscopelids. In addition, because reconstruction of the evolutionary processes of morphological characters, based on the “morphology-based tree”, involves circular logic, molecular phylogenetic approaches are now seen as indispensable. A robust molecular phylogenetic tree may contribute to a better understanding of the evolutionary patterns and processes of morphological characters.
The appearance sequence of calcified germ teeth and morphological changes in pharyngeal teeth of Gnathopogon elongatus elongatus larvae and juveniles, obtained from artificially fertilized eggs of fish caught in a canal in Nagahama City, facing Lake Biwa, are described. The appearance sequence of calcified germ teeth was similar to those in G. caerulescens, both species exhibiting the socalled “A-type” pattern. Morphological changes in the pharyngeal teeth were divided into six stages, the first five being similar to comparable stages in Mylopharyngodon piceus. However, teeth at the sixth stage differed from those in M.piceus, the latter beeing characterized by a smooth grinding surface.
A total of 61, 388 fish specimens, representing about 60 species, were collected by monthly seine-net (mesh size 0.8 mm) samplings at the seven tidelands in the inner Tokyo Bay, Pacific coast of central Japan, from April 1997 to March 1998. Two gobiid species, Acanthogobius flavimanus and Chaenogobius macrognathos, were the most abundant species, contributing 52.6 and 20.7% of the total number of fishes, followed by Chaenogobius castaneus (7.7%), Lateolabrax japonicus (6.3%) and Mugil cephalus cephalus (6.0%). Eight “estuarine” and 19 “marine” species, which occupying 99.4% of total number of fishes, were highly possibly c0onsidered to depend on tidelands for their considerable part of life history, because of the occurrence of some developmental stages. The diversity of fish community was higher in Obitsu River and Edo River than in other five sites, in the first two rivers, large tidelands having remained in spite of coastal construction since 1950's. The results of this study would indicate that the diversity of fish community at tidelands reflect more or less an impact of emvironmental changes by the reclamation of the inner Tokyo Bay.
A single specimen of the holocentrid fish, Myripristis robusta Randall& Greenfield, collected at a depth of ca. 50 m in Funauki Bay, Iriomote Island, Ryukyu Islands, Okinawa Prefecture, represents the northernmost record of the species and the first record from Japan. The specimen (175 mm in standard length) is described and a new Japanese name “Yuyake-matsukasa” is proposed to the species.
A single carangid specimen (MUFS 12564, 204 mm standard length and 225 mm fork length), collected by a small set net within ca. 10 m depth at Meitsu, Nango, Miyazaki, Kyushu Island, Japan (131°23.5'E, 31°31.9'N), was identified as Trachinotus mookalee Cuvier in Cuvier & Valenciennes, on the basis of its short second dorsal fin lobe (24.0% of fork length) and anal fin coloring (lobe anteriorly yellow-golden, with weak melanophores). The specimen repre-sents the northernmost record of the species and first record from Japan. Observa-tions (at Nagasaki and Kanagawa Prefectures, Japan) of larger examples (ca. 60-90 cm in total length) of the species suggested a wide distribution around southern Japan, except the Ryukyu Islands. The specimen is described and a new Japanese name “kogane-marukoban” proposed for the species.
Intraspecific genetic differences in the seahorse, Hippocampus corona-tus (Syngnathiformes: Syngnathidae), collected from Sagami Bay (Shizuoka and Kanagawa Prefectures, Japan), were surveyed by molecular phylogenetic analyses using a portion of the mitochondrially-encoded 12S ribosomal RNA (12S rRNA) gene. The results indicated that the species comprised two genetically-divergent clades, one characterized by a low coronet and short snout and the other by a tall coronet and long snout. Although the sequence divergences within each clade were very low (0-0.1%), that between the two clades was relatively high (4.4-4.6%), close to values recorded for interspecific genetic divergences in this genus (5.5-7.5%). This suggests that H. coronatus includes at least two taxonomic units.