Siphonogobius nue, a new genus and species of gobiid fish from japan

A new genus and species of gobiid fish,Siphonogobius nue, based on 15 specimens, is described from temperate Pacific coasts of Japan. It is unique amongst gobioids in having a simple tube-like infraorbital canal extending below the eye and the oculoscapular canal between pores A' and L' without openings, except for the terminal pores and pore D. Although well-developed infraorbital canals occur in two other gobioid genera, the rhyacichthyidRhyacichthys and the gobiidLophiogobius, such are distinct from that ofSiphonogobius in having several branches and openings. Furthermore, the new taxon is distinguished from all other gobioids by the following combination of characters: first dorsal-fin spines 7–9 (usually 8); pectoral-fin rays 24–26, the upper 7–9 rays free from the fin membrane; pelvic frenum thick, robust and slightly emarginate posteriorly; scales small and cycloid, 87–96 in longitudinal series; vertebrae 14–15+19–20=33–34 (usually 14+20=34); P-V usually 3/I II II I I I 0/11; anal-fin pterygiophores anterior to the first haemal spine 3–4 (usually 3); a row of short fleshy flaps on the ventral surface of the head, extending from the lower edge of the preopercle to the chin; anterior nostril with a minute skin flap. Axial skeletal features indicated thatSiphonogobius is closely related to a group which includesAcanthogobius and its relatives.     

Larval development of Balanus reticulatus Utinomi, 1967 (Cirripedia, Thoracica) and a comparison with other barnacle larvae

The morphological features of the cephalic shield, labrum, abdominalprocess, antennules, antennae and mandibles of Balanus reticulatusare described and illustrated. The size and setation formulaeof the larvae are given at each stage. The trilobed labrum andlateral margin of the cephalic shield with numerous small spinesare diagnostic features for all the subsequent nauplius stages.Numerous small denticulate processes on the surface of the cypridcarapace are major morphological characteristics not found inother balanomorph species. We have constructed keys from stageII to stage VI for the predominant barnacle nauplii of Koreancoastal waters, based on morphological traits such as totallength, shield width, labrum shape, the presence or absenceof posterior shield spines and dorsal shield spines in stagesIV, V and VI, the specific setal type in the fourth segmentof the antennal endopodite, and setation formulae of Pollicipesmitella, Chthamalus challengeri, Megabalanus rosa, B.reticulatus,Balanus amphitrite and Balanus albicostatus.     

Review of the Indo-Pacific gobiid fish genus Lubricogobius, with description of a new species and a new genus for L. pumilus

The gobiid genus Lubricogobius Tanaka, distinctive in being scaleless, without sensory pores, but with sensory papillae on the head, consists of three small species (largest, 33.7 mm SL): the yellow L. exiguus Tanaka, type species, from Japan, with probable records from Taiwan and New Caledonia; L. ornatus Fourmanoir, orange with blue lines on the head, described from Vietnam, recorded from the Arafura Sea, and the range here extended to the Timor Sea and Northwest Shelf of Western Australia, Ryukyu Islands, and to New Caledonia; and L. dinah, a new species from Papua New Guinea and the Ryukyu Islands, white dorsally and abruptly orange-yellow ventrally, with 10–11 dorsal soft rays. L. pumilus Larson and Hoese, known from one 14.5-mm specimen from off Somalia, is referred to the new genus Larsonella. The new genus differs from Lubricogobius in having scales posteriorly on the body, a more slender body, depressed head, no pelvic frenum, the snout longer than orbit diameter, and a different pattern of sensory papillae on the head. Received: September 30, 1999 / Accepted: June 9, 2000     

Platygobiopsis akihito,new genus and species of gobiid fish from Flores,Indonesia

Platygobiopsis akihito is described from 12 specimens 63.4-95.9 mm SL. It is most closely related toGobiopsis Steindachner, based on the presence of a pair of chin barbels and two horizontal, fleshy, papillae-bearing folds on the cheek, and the absence of vertical papillae-bearing folds on the sides of the anterior half of the head.Platygobiopsis differs most obviously from all the species Lachner and McKinney (1978, 1979) included inGobiopsis in having an exceedingly depressed head and body (both the most depressed of any gobioid), an elongate form (depth 4.5-5.8% SL), and in its dorsal- and anal-fin formulae: D. VI-I, 12, A. I, 12, which include at least one more segmented dorsal-fin ray and two more segmented anal-fin rays than is known to occur in any species ofGobiopsis.     

Reproductive strategy and interspecific competition in the Lake-living gobiid fish isaza,Chaenogobius isaza

Isaza,Chaenogobius isaza, is a small gobiid fish endemic to Lake Biwa. It lives offshore throughout almost the entire year, showing a remarkable diel vertical migration. In early spring, males and females migrate to lake shore to spawn under stones. Spawning season is limited to a very short span of time in early spring, late April to early May. During this short spawning season, the male is supposed to have only 2 brood cycles at maximum. At each brood cycle, the male is strictly monogynous, never accepting additional females. Males therefore show a marked mate choice, choosing a larger female regardless of the size of the male himself. Females also choose larger males. However, males are supposed to not waste time in male-male fighting in the natural spawning area. That this very short spawning season and its occurrence in early spring is primarily to avoid interspecific competition with another littorally reproducing goby Yoshinobori,Rhinogobius brunneus, is experimentally demonstrated.     

Larval development of the Indo-Pacific perciform fish,Centrogenys vaigiensis (Pisces: Centrogeniidae)

Based on seven larvae from northern Australia, development ofCentrogenys vaigiensis—a species of uncertain phylogenetic affinities—is described for the first time. Identification was established from meristic and osteological characters. Development is characterized by few morphological specializations and is apparently completed at a small size (ca 5 mm standard length). Larvae are deep-bodied and compressed, with very limited head spination (small spines on preopercle, subopercle, opercle and supracleithrum). Fin development takes place at about the time of notochord flexion, and is complete at about 4.3 mm, with the exception of anal spine three, which does not fully transform from a soft ray until after settlement. Fin spines are short, smooth and weak. Larvae are apparently limited to near-shore, shallow marine waters, and based on the size of what are apparently settlement-stage larvae, the pelagic period may be short.     

Larval development and metamorphosis in Pleurobranchaea maculata, with a review of development in the notaspidea (Opisthobranchia)

Pleurobranchaea maculata is a carnivorous notaspidean that is common in New Zealand. This species produces small eggs (diameter 100 microm) and planktotrophic veligers that hatch in 8 d and are planktonic for 3 weeks before settling on biofilmed surfaces (14 degrees C). Larval development is known in detail for only two other notaspidean species, P. japonica and Berthellina citrina. In all three species of pleurobranchids, mantle and shell growth show striking differences from veligers of other opisthobranch taxa. In young veligers of pleurobranchids, the shell is overgrown by the mantle, new shell is added by cells other than those of the mantle fold, and an operculum does not form. Thus some "adult" traits (e.g., notum differentiation, mechanism of shell growth, lack of operculum) are expressed early in larval development. This suggests that apomorphies characteristic of adult pleurobranchids evolved through heterochrony, with expression in larvae of traits typical of adults of other clades. The protoconch is dissolved post-settlement and not cast off as occurs in other opisthobranch orders, indicating that shell loss is apomorphic. P. maculata veligers are atypical of opisthobranchs in having a field of highly folded cells on the lower velar surface, a mouth that is posterior to the metatroch, and a richly glandular, possibly chemodefensive mantle. These data indicate that notaspidean larvae are highly derived in terms of the novel traits and the timing of morphogenic events. Phylogenetic analysis must consider embryological origins before assuming homology, as morphological similarities (e.g., shell loss) may have developed through distinct mechanisms.     

Histological observation of the urogenital papillae in the bi-directional sex-changing gobiid fish, Trimma okinawae

The gobiid fish Trimma okinawae changes its sex bi-directionally according to its social status. Morphological changes in the urinogenital papillae (UGP) of this fish have been reported during sex change. However, there have been no detailed observations of such changes. Here, we histologically examined the UGP structure of male- and female-phase fish. UGPs of fish in female and male phase contained both oviducts and sperm ducts. Both ducts were coalesced into one duct within the posterior region of the UGP. Female-phase fish had many longitudinal folds in the hypertrophied tunica mucosa of the oviduct, which was found to be responsible for the transport of eggs and the removal of follicular cells from the oocyte. In contrast, male-phase fish had an immature oviduct and a mature sperm duct in the UGP. In the male-phase fish, the co-existence of spermatozoa and fibrillar secretions was observed in the sperm duct during spermiation.     

Differences in the activity rhythms of juvenile gobiid fish,Chasmichthys gulosus,from different tidal localities

Activity patterns of intertidal gobiid fish,Chasmichthys gulosus, collected from different tidal localities, were recorded in a constant environment. Gobies collected from a rocky shore with a large tidal range and a regular tidal regime displayed a ca. 12 hour rhythm in their activity pattern. Gobies from a rocky shore with a small tidal range and an irregular tidal regime, however, did not clearly display any such rhythm. The ecological implications of such activity rhythms are discussed from the viewpoints of feeding and avoidance of predators.     

Plate-like permanent dental laminae of upper jaw dentition in adult gobiid fish, Sicyopterus japonicus

Sicyopterus japonicus (Teleostei, Gobiidae) possesses a unique upper jaw dentition different from that known for any other teleosts. In the adults, many (up to 30) replacement teeth, from initiation to attachment, are arranged orderly in a semicircular-like strand within a capsule of connective tissue on the labial side of each premaxillary bone. We have applied histological, ultrastructural, and three-dimensional imaging from serial sections to obtain insights into the distribution and morphological features of the dental lamina in the upper jaw dentition of adult S. japonicus. The adult fish has numerous permanent dental laminae, each of which is an infolding of the oral epithelium at the labial side of the functional tooth and forms a thin plate-like structure with a wavy contour. All replacement teeth of a semicircular-like strand are connected to the plate-like dental lamina by the outer dental epithelium and form a tooth family; neighboring tooth families are completely separated from each other. The new tooth germ directly buds off from the ventro-labial margin of the dental lamina, whereas no distinct free end of the dental lamina is present, even adjacent to this region. Cell proliferation concentrated at the ventro-labial margin of the dental lamina suggests that this region is the site for repeated tooth initiation. During tooth development, the replacement tooth migrates along a semicircular-like strand and eventually erupts through the dental lamina into the oral epithelium at the labial side of the functional tooth. This unique thin plate-like permanent dental lamina and the semicircular-like strand of replacement teeth in the upper jaw dentition of adult S. japonicus probably evolved as a dental adaptation related to the rapid replacement of teeth dictated by the specialized feeding habit of this algae-scraping fish.     

Spatiotemporal and gender‐specific parasitism in two species of gobiid fish

Parasitism is considered a major selective force in natural host populations. Infections can decrease host condition and vigour, and potentially influence, for example, host population dynamics and behavior such as mate choice. We studied parasite infections of two common marine fish species, the sand goby (Pomatoschistus minutus) and the common goby (Pomatoschistus microps), in the brackish water Northern Baltic Sea. We were particularly interested in the occurrence of parasite taxa located in central sensory organs, such as eyes, potentially affecting fish behavior and mate choice. We found that both fish species harbored parasite communities dominated by taxa transmitted to fish through aquatic invertebrates. Infections also showed significant spatiotemporal variation. Trematodes in the eyes were very few in some locations, but infection levels were higher among females than males, suggesting differences in exposure or resistance between the sexes. To test between these hypotheses, we experimentally exposed male and female sand gobies to infection with the eye fluke Diplostomum pseudospathaceum. These trials showed that the fish became readily infected and females had higher parasite numbers, supporting higher susceptibility of females. Eye fluke infections also caused high cataract intensities among the fish in the wild. Our results demonstrate the potential of these parasites to influence host condition and visual abilities, which may have significant implications for survival and mate choice in goby populations.     

Maturation and spawning of a gobiid fish, Oligolepis acutipennis (Cuv. & Val.), from the south-west coast of India

The breeding biology of Oligolepis acutipennis (C. & V.), a gobiid fish abundant in the estuaries and brackish water tracts of the south-west coast of India was studied. Data on the intra-ovarian development of ova, the breeding season, spawning frequency, size at first maturity and sex-ratio were based on observations for 1 year. The size distribution of ova showed no significant variation between different regions of the ovary. The gonads were classified into five maturity stages. The sequence of development of ova to maturity indicated two batches of ova developed in a single ovary in a year. The minimum size at first maturity of females was less than that of males. Seasonal variation in gonad weight and the percentage occurrence of various maturity stages of gonads showed that the fish has a protracted breeding period in which two seasons can be recognized. The females dominate over males in numbers except in the non-breeding months.     

Larval development and settlement of a whale barnacle

Larval development and settlement of whale barnacles have not previously been described, unlike intertidal barnacles. Indeed, the mechanisms of the association between barnacles and whales have not been studied. Here we describe the larval development and settlement of the whale barnacle, Coronula diadema, and possible involvement of a cue from the host in inducing larval settlement. Eight-cell stage embryos were collected from C. diadema on a stranded humpback whale, incubated in filtered seawater for 7 days, and nauplius larvae hatched out. When fed with Chaetoceros gracilis, the nauplii developed to stage VI, and finally metamorphosed to the cypris stage. The larval development looked similar to that of intertidal barnacles with planktotrophic larval stages. The cyprids did not settle in normal seawater, but did settle in polystyrene Petri dishes when incubated in seawater with a small piece of skin tissue from the host whale. This strongly suggests the involvement of a chemical cue from the host whale tissue to induce larval settlement.     

Reproduction of a fish assemblage in the state of S?o Paulo, southeastern Brazil.

Fish reproductions were studied in two river basins (Corumbataí and Jacaré-Pepira basins) in the State of S?o Paulo, southeastern Brazil. In the Corumbataí basin, four sites were sampled: Cabe?a River, Lapa Stream, Passa-Cinco River, and Corumbataí River; in the Jacaré-Pepira basin, three sites were sampled: Tamanduá Stream, Jacaré-Pepira River, and Agua Branca Stream. A total of 12 bimonthly samples were made. Fish equipment included gill nets, purse seines, sieves, and traps. The main objective of this study was to characterize the fish assemblage regarding their reproductive biology and to compare these reproductive traits between both river basins. Most individuals with gonads in stage C (mature) and in stage D (empty gonads) were captured in the spring and summer. Multiple spawn and parental care were common strategies, which guaranteed offspring survivorship in unstable conditions.