Larvae of two pleuronectiforms, Poecilopsetta plinthus (Poecilopsettidae) and Parabothus coarctatus (Bothidae), from southern Japan

Pelagic larvae of two pleuronectiforms, Poecilopsetta plinthus (Poecilopsettidae) and Parabothus coarctatus (Bothidae), are described and illustrated based on specimens collected off Tosa Bay, southern Japan. Postflexion larvae (8.2–11.9 mm BL) of Poecilopsetta plinthus are characteristic in having a series of melanophore patches along the dorsal and anal fin bases and the inner margins of the pterygiophore zones, and linear myoseptal pigmentation also along the inner margins of the latter. Preflexion and flexion larvae (5.0–6.3 mm BL) of Parabothus coarctatus are distinctive in having the dorsal fin origin located level with the dorsal margin of the eye and seven elongated rays in the anterior part of that fin. Received: November 18, 2000 / Revised: May 1, 2001 / Accepted: June 13, 2001     

Larvae and juveniles of Leptoderma lubricum and L. retropinnum (Argentiformes: Alepocephalidae) collected from Suruga Bay, Japan

Larvae and juveniles of the alepocephalid fishes, Leptoderma lubricum [26.9–69.0 mm in standard length (SL)] and Leptoderma retropinnum (21.1–67.2 mm SL), collected within 1–8 m of the seafloor in Suruga Bay, southern Japan, are described. They can be easily distinguished from each other by the following adult-like characters: membrane morphology between the vertical fin rays and procurrent caudal-fin rays (separated in L. lubricum vs. continuous in L. retropinnum), numbers of dorsal-fin rays (34–40 vs. 45–52) and anal-fin rays (50–57 vs. 65–72), and caudal peduncle length (11.7–13.4% SL vs. 4.5–5.9% SL), in addition to several other body proportional differences. Unique characters in the larval stages of Leptoderma include a translucent occipital region, horizontally elongated eye, and head below the upper margin of the orbit and abdominal cavity densely covered by melanophores, ontogeny being characterized by the acquisition of general adult characters to the postflexion stage, indistinct transformation, and the retention of few larval characters until almost the end of the juvenile stage, as in other known alepocephalids. In addition to the near-bottom larval and juvenile collections of both species, the occurrences of benthic or near-bottom taxa, including Harpacticoida, in their gut contents confirmed the early life history dependence of the former on the near-bottom.     

Larvae of Diagramma pictum (Haemulidae) from Tosa Bay, Japan

Preflexion to postflexion larvae (2.1–8.0 mm) of Diagramma pictum (Haemulidae) occur in coastal Tosa Bay, Japan from May to September. They can be distinguished from the other haemulid larvae by head spination, location of anus, and melanophore patterns. Compared with larvae identified as the same species from Australia, there are significantly morphological differentiations between the two areas. Thus, these significant differences are likely a reflection of subspecific differences.     

Early ontogeny of Lophonectes gallus (Bothidae) from southeastern Australia

 The early ontogeny of Lophonectes gallus (Bothidae) is described based on 83 specimens (1.9–17.5 mm BL), collected from the Tasman Sea off southeastern Australia. The larvae are diagnosed by the following array of characters: vertebrae 10 + 30–31 = 40–41; one elongated dorsal fin ray and several melanophores present on gut in preflexion stage (1.9–4.7 mm BL); and spines on posterior basipterygial process, and urohyal, cleithrum, and epiotic without spines after postflexion stage (8.0–17.5 mm BL). The larvae are relatively small at metamorphosis (15–18 mm BL) compared with other bothid larvae. Received: March 22, 2001 / Revised: December 12, 2001 / Accepted: December 26, 2001     

Larvae of <Emphasis Type="Italic">Arnoglossus elongatus</Emphasis> (Pleuronectiformes: Bothidae) from northwestern Australia

Eleven postflexion larvae (9.1–23.9mm standard length: SL) of a bothid, Arnoglossus elongatus, from northwestern Australian waters were described. These specimens were characterized by vertebral numbers of 11–12+32–34=43–45, slender body, remarkably elongated second dorsal fin ray, and presence of melanophores on and slightly above midlateral line of body, plus on dorsal wall of abdominal cavity and air bladder (specimens >12.6mm SL), proximally on caudal fin rays (>16.5mm SL), and on pterygiophore zones of dorsal fin and anal fin (>23.8mm SL).     

Larvae and Juveniles of the Genus Liparis (Pisces: Liparidae) from the Northwestern Sea of Japan

Larvae and juveniles of Liparis ochotensis, L. latifrons, L. tartaricus, L.brashnikovi, and L. kusnetzovi (Liparidae) are described for the first time based on ichthyoplankton catches carried out in the northwestern Sea of Japan in the decade 1992–2002. Our earlier published data on the larval development of L. agassizii and juveniles of L. punctulatus are supplemented. It is shown that larval development in the Liparis includes a planktonic stage. The larvae of different species turn into juveniles at a different lengths: under 15 mm in the case of littoral species and at about or over 20 mm in the case of sublittoral species. The major morphological characteristics of larvae of different Liparis species—body height and shape, pelvic disk length, preanal length, presence of a notch in the dorsal fin, pigmentation pattern, and others—have been distinguished. Original illustrations of larvae and juveniles are provided.     

New species of kathlaniid (Nematoda: Cosmocercoidea) collected from hynobiid salamanders in Japan

Falcaustra odaiensis n. sp. (Nematoda: Cosmocercoidea: Kathlaniidae) is described from the Japanese clawed salamander, Onychodactylus japonicus (Houttuyn, 1782), and Ishizuchi salamander, Hynobius hirosei Lantz, 1931 (Caudata: Hynobiidae), in Japan. This nematode is characterized by having multiple pseudosuckers in the male. It resembles Falcaustra araxiana, Falcaustra duyagi, Falcaustra lambdiensis, Falcaustra pillaii, Falcaustra siamensis, and Falcaustra washingtonensis, but is readily distinguished by the spicule length and/or egg size. This is the first Falcaustra species described from Japanese salamanders.     

A new species ofArnoglossus (Pleuronectiformes: Bothidae) from the southwestern coast of Australia

A new bothid flounder,Arnoglossus micrommatus, is described from the southwestern coast of Australia (off Albany, Western Australia). This species is distinguished from other species ofArnoglossus by combination of the following characters: gill-rakers serrated on posterior margin; upper jaw length 2.83–3.12 in head length (HL); upper eye diameter 4.17–5.51 in HL; scales in lateral line 52–62; vertebrae 11+28−29=3t-40.     

The Larvae of Unarmed Nemerteans in Peter the Great Bay (Sea of Japan)

Nemertean pilidia belonging to the groups magnum, pyramidale, gyrans, recurvatum, and auriculatumwere found in Peter the Great Bay. Pilidium auriculatumis probably a little-known ribbon worm of the family Hubrechtiidae, which has never before been found in the Sea of Japan. Larvae of two species of the order Archinemertea were also found.     

Sexual dimorphism of the flounder Bothus robinsi (Pisces: Bothidae)

The anatomical organization of the reproductive system of the flounder, Bothus robinsi, is similar to other fish in the order Pleuronectiformes. Accentuated, external secondary sexual characters are observed in males such as increased body length, larger left pectoral fin, and greater interorbital distance. As a qualitative character, the rostral spine, which is part of the maxillary bone, is pronounced. The interorbital distance implies noticeable internal sexual differences, such as the broadening of the left frontal and lateral ethmoid bones, and a greater length of the oblique muscles of both eyes, the optic nerves, and the left olfactory nerve. Five male specimens examined had female external secondary sexual characters.     

A pre-leptocephalus larva ofConger myriaster (family Congridae) collected from Suruga Bay,Central Japan

One specimen of leptocephalus larva, measuring 16.0 mm in total length, was collected from the northern part of Suruga Bay (34°56′N, 138°39′E) by the T/V Bosei Maru II of Tokai University on November 7, 1982. This larva is identified asConger myriaster because of having melanophores under the eye, simple gut with melanophores, 142 total number of myomeres and the position of the last vertical blood vessel at the 52nd myomere. Judging from the body length, appearances of teeth and fins, and disposition of the anus, the present larva belongs to the preleptocephalus stage. The presence of this early larva in this area suggests that one of the spawning grounds ofC. myriaster exists in or near Suruga Bay in autumn.     

A new flounder,monolene helenensis (pleuronectiformes: Bothidae) from the eastern tropical atlantic

Monolene helenensis sp. nov. is described on the basis of seven specimens collected from the eastern tropical Atlantic Ocean. This new bothid flounder differs from all known congeners by the following combination of characters: 108–116 dorsal and 89–92 anal fin rays, 101–111 lateral line scales, 7–10+10–15=18–25 gill rakers, 10–12+37–38=48–50 vertebrae, body depth 2.58–2.77 in standard length, ocular side pectoral fin length 1.34–1.59, in head length and upper half of pectoral fin blackish.     

A preliminary study of two species of flatfish (family: Bothidae) from the south-west Atlantic

Two species of the family Bothidae (lefteye flounders), Mancopsetta maculata metadata and M. milfordi occur in the south-west Atlantic but are caught rarely by commercial bottom trawlers. Little is therefore known about their general biology from this area. A total of 251 M. maculata and 276 M. milfordi were sampled during deep-water exploratory fishing conducted in November 1994 within the Falkland Islands Interim and Outer Conservation Zones, at depths of 400-1000 m, using standard commercial bottom trawling gear. The two species were found to have similar geographical distributions between 48.30'-53.30'S and 55°-62° W and were often obtained at the same stations in depths of 400-900 m on the continental slope. Mancopsetta maculata maculata showed a uni-modal cohort structure with a modal length at the 29-cm total length size-class. Males of M. m. maculata outnumbered females in a ratio of 3.5 : 1. Mancopsetta milfordi showed a tri-modal length distribution, the main mode at the 37-cm total length size-class, with females outnumbering males in a ratio of 1.1 : 1. Length-weight relationships and length-at-age information are presented for the two species. Diet was determined from the analysis of stomach contents and, although the major prey type for both species consisted of crustaceans, the morid fish Austrophycis marginata also formed an important part of the diet of M. milfordi. Key words: Mancopsetta maculata maculata; Mancopsetta milfordi; distribution; south-west Atlantic; size; diet.     

Engyprosopon marquisensis, a new species of bothid flounder (Pleuronectiformes: Bothidae) from the Marquesas Islands (French Polynesia)

A new bothid flounder, Engyprosopon marquisensis, is described from 11 specimens collected in deep waters (108–408 m) off the Marquesas Islands (French Polynesia) during the French exploratory cruise MUSORSTOM 9 in 1997. Engyprosopon marquisensis is similar to E. bellonaensis from the Chesterfield Islands and Bellona Plateau in the Coral Sea and E. vanuatuensis from off Vanuatsu Island, but is easily distinguished from E. bellonaensis by the following combination of characters: narrow interorbital space in both sexes, small mouth, short caudal fin, large number of vertebrae, and fewer gill rakers. It differs from E. vanuatuensis by many scales in the lateral line, small eyes, short ocular-side upper jaw, and short blind-side lower jaw. Engyprosopon marquisensis is the deepest occurring (408 m) species of the genus, and constitutes the second species of this genus with an eastern distribution.     

Pelagic eggs and larvae of Coelorinchus kishinouyei (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

Pelagic eggs and larvae of the macrourid fish Coelorinchus kishinouyei, collected from Suruga Bay, southern Japan and subsequently identified by 16S rRNA gene nucleotide sequences, are described. The spherical eggs, 1.18–1.31 mm in diameter, contained a single oil globule, 0.28–0.33 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.017–0.022 mm in width. Melanophores were present on the embryo, yolk and oil globule after the blastopore had closed. Within 1 day after hatching, the body axis of the yolk-sac larvae was bent slightly at the anterior trunk region. During this stage many melanophores formed on the head, trunk, tail, yolk and oil globule, along with small irregular wrinkles on the dorsal and ventral finfolds. Pelagic eggs (after the caudal end of the embryo had detached from the yolk) and yolk-sac larvae also developed xanthophores on the embryo and yolk, and head, trunk, dorsal and ventral finfolds just before tail tip, and yolk, respectively. The pelagic larvae had a short tail, stalked pectoral-fin base and no elongate first dorsal and pelvic-fin rays. Three clusters of melanophores were present on the tail (anterior two embedded to muscle and one just before tail tip subsequently lost with development) and a cluster around the anus (beyond 3.9 mm head length). Nucleotide sequence analyses of comparative adult specimens appeared to confirm a previous proposal that C. productus is a junior synonym of C. anatirostris.     

Pelagic eggs and larvae of Coryphaenoides marginatus (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

The pelagic eggs, yolk-sac and pelagic larvae of the macrourid fish, Coryphaenoides marginatus, from Suruga Bay in southern Japan, are described. The identification of the pelagic eggs based on 16S rRNA gene nucleotide sequences agreed with that obtained from morphological analyses. The spherical eggs, 1.14–1.30 mm in diameter, contained a single oil globule 0.30–0.38 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.025–0.033 mm in width. Many melanophores were present on the anterodorsal region of the embryo after the caudal end had detached from the yolk. Within a day after hatching, each of the yolk-sac larvae had a body axis that was bent slightly at the anterior trunk region, many dorsal and lateral melanophores on the trunk plus several on the gut, and small irregular wrinkles on the dorsal and anal fin membranes. The pelagic larvae had a short caudal region in comparison to other known congeners (length 2.0–3.2+ times head length vs. 4–7, respectively), a short stalked pectoral fin base, and no elongate first dorsal and pelvic fin rays. They were further characterized by the presence of numerous very dense melanophores from just behind the eye to the anterior part of the caudal region at 5.1 mm head length (25.8+ mm total length). The significant difference in vertical distribution between the pelagic eggs and larvae (dominant depths ca. 200–350 m vs. ca. 10–100 m, respectively), with no subsequent collection of pelagic larvae with greater than 6 mm head length, indicate two stages (rising and falling) of ontogenic vertical migration.     

Larvae of phoronids (Phoronida) from Terpeniya Bay (Southeastern Sakhalin)

Phoronid larvae were found in planktonic samples from the northern coast of Terpeniya Bay. In some samples, their density was up to 220 specimens/m³. Larval stages having 10, 12, 16, 20, and 22 tentacles are described. Larvae were identified as Actinotrocha branchiata and belong to the species Phoronis muelleri Selys-Longchamps, 1903. However, unlike the Ph. muelleri larvae described in the literature, the larvae we found are smaller (not more than 900 μm) before metamorphosis and have fewer tentacles (24). They lack paired vacuolated diverticula of the stomach, which are characteristic of Ph. muelleri larvae. However, judging by all other characters, namely transparency, the absence of coelomic cylinder in the preoral lobe, and the presence of adult tentacle primordia, one pair of blood cell aggregations, and a pyriform organ, these larvae are similar to the previously described larvae of Ph. muelleri. Adult forms of Ph. muelleri were previously found in Terpeniya Bay and described by Mamkaev (1962) and Emig (1984).     

A new genus and species of hatschekiid copepod (Siphonostomatoida) from groupers (Actinopterygii: Serranidae) collected off the Ryukyu Archipelago, Japan

A new genus and species of copepod, Mihbaicola sakamakii n. g., n. sp., belonging to the siphonostomatoid family Hatschekiidae, is described based on the females collected from inside the tissue of the branchiostegal membrane in three species of the groupers, Epinephelus fasciatus (Forsskål) (type-host), E. merra Bloch and Cephalopholis leopardus (Lacépède), collected off Okinawa-jima Island and Iriomote-jima Island, Ryukyu Archipelago, North Pacific Ocean. The new genus can be distinguished from other hatschekiid genera by a combination of the following characters in the female: the head is composed of the cephalosome and the pedigerous somite; the cephalothorax is expanded into a pair of posteroventral lobes carrying leg 1; legs 1 and 2 are biramous and composed of the protopod and both rami are 2-segmented; leg 3 is absent; and leg 4 is represented by a rounded lobe with a chitinous pointed apical process.