A new loach, Cobitis shikokuensis (Teleostei: Cobitidae), from Shikoku Island, Japan

A new species of spinous loach, Cobitis shikokuensis, is described based on 297 specimens from Shikoku Island, Japan. The new species was formerly known as the Shikoku group of Cobitis takatsuensis. It can be distinguished from other species of Cobitis and closely related genera by a combination of the following characters: dorsal fin with 6 branched soft rays; anal fin with 5 branched soft rays; one brownish streak across eye from the tip of nose, no streak on cheek; a black spot smaller than eye diameter near the dorsal corner of the caudal fin base; 3–5 small brownish speckles on ventral side of caudal peduncle; high caudal peduncle with well-developed fleshy keels on dorsal and ventral side; a lamina circularis at base of dorsal part of pectoral fin absent; first branched soft ray of pectoral fin broad in males; pectoral soft rays widely branched from the approximate midpoint; last anal fin ray with 2 elements; interorbital width 11.2–17.1% of head length.     

Effects of 17α-Methyltestosterone on Sexually Dimorphic Characters in the Weakly Discharging Electric Fish,Brienomyrus niger(Günther, 1866) (Mormyridae): Electric Organ Discharge, Ventral Body Wall Indentation, and Anal-Fin Ray Bone Expansion

Adult males of African weakly discharging electric fish (family: Mormyridae) are distinguished from juveniles and adult females by a dorsally directed indentation of the posterior ventral body wall and by massive bone expansion of the bases of a select number of anal-fin rays. These sexually dimorphic structures seem to facilitate the anal-fin reflex that is displayed during courtship when the male envelopes its anal fin around the female's to form a common spawning pouch. Expanded bone could provide additional surface for muscle attachment and thus assist in part with the courtship sequence. Based on the fact that the expression of the male sexually dimorphic electric organ discharge (EOD) is under androgen control, and that the female EOD can be masculinized through testosterone administration, we hypothesized that androgens should also drive anal-fin ray bone expansion in male mormyrids and equally effect male-like changes in treated juveniles and adult females. Exogenous androgen treatment (17α-methyltestosterone) of adult femaleBrienomyrus nigerresulted in a male-like EOD, and male-typical structural transformations (body wall indentation and anal-fin ray bone expansion). Some of these changes were immediate and receded following hormone withdrawal (EOD), while others developed more slowly and were apparently permanent (indentation and bone formation). 17α-Methyltestosterone administration affected only those targets in females that are normally involved in the male's reproductive behavior, i.e., its courtship signal (EOD) and two morphological features (body-wall indentation and bone expansion). Rays of the dorsal or caudal fins were never affected.     

17α-甲基睾酮对剑尾鱼的影响

目的研究17α-甲基睾酮暴露对产后雌性剑尾鱼(Xiphophorus helleri)性逆转组织形态学变化的影响,探讨剑尾鱼第二性征变化作为水环境风险评价(ERA)的有效生物学标记的可能性。方法使用浸浴法以10μg/L 17α-甲基睾酮为剑尾鱼染毒持续7周,对实验鱼的体形、腹鳍、臀鳍、尾鳍及性腺等组织器官的变化进行观察;同时对幼鱼在实验室养殖条件下的性别分化进行统计。结果 17α-甲基睾酮对产后雌鱼有明显的影响,受诱导后出现性逆转,逐渐发育形成雄性第二性征:体形变纤细;腹鳍第1鳍条变短、第2和第3鳍条延长,臀鳍第3、4、5鳍条末端钩状化且第3鳍条变粗壮,尾鳍上下缘出现增生;体内与臀鳍相连的骨骼合并生长;受诱导的雌鱼性腺呈现退化趋势并伴有卵细胞坏死现象,生殖能力受到负面影响。结论剑尾鱼臀鳍和尾鳍变化可作为水环境雄激素物质污染监测的有效生物学标记。     

Descriptive morphology of pelagic juvenile of <Emphasis Type="Italic">Lepidion inosimae</Emphasis> (Gadiformes: Moridae) collected from off northeastern Japan

A pelagic juvenile (74.0 mm in standard length) of Lepidion inosimae was collected by midwater trawl (0–20 m depth) from the transition waters between the Kuroshio and Oyashio fronts off northeastern Japan. The specimen is characterized by an elongate body, a chin barbel, a minute first ray and non-elongated second ray of first dorsal fin, combination of 55 second dorsal fin rays and 52 anal fin rays, and no ventral luminous organ. This is the first report of early life stages in the genus Lepidion.     

A new anthiine fish (Perciformes: Serranidae),Holanthias kingyo, from the Ryukyu Islands

A new anthiine fish,Holanthias kingyo sp, nov., is described on the basis of two specimens (male and female) from the Ryukyu Is., Japan. The new species is most similar toH. natalensis (Fowler, 1925), known only from South Africa, in having the following characters: dorsal fin soft rays 16 or 17, anal fin soft rays 9, pored lateral line scales 46 or 47, scale rows above lateral line to origin of dorsal fin 9 1/2 or 10 1/2, and gill rakers 10 or 11 +24 or 25=34–36. It differs from the latter in having more scales below the lateral line to the origin of the anal fin (27 1/2 vs. 18–24), a U-shaped caudal fin with paddle-like lobes (vs. deeply forked caudal fin with each lobe ending in a long slender filament), the outer margin of the soft anal fin vertical (vs. gently convex) and brown spots on the body in female (vs. spots absent in females).     

A new species,gerres infasciatus, from the gulf of thailand (perciformes: Gerreidae)

Gerres infasciatus sp. nov. is described from the holotype and two paratypes, 125–140 mm in standard length (SL), collected off Samut Prakan, northern Gulf of Thailand. The species is similar toG. filamentosus Cuvier andG. macracanthus Bleeker in general appearance, having an elongated second dorsal fin spine, but differs from them in having 39 or 40 pored lateral line scales, the first and second soft dorsal fin ray tips yellow in fresh specimens, a narrow, faint dusky-yellowish margin on the upper membrane of the spinous dorsal fin (between 4th–9th spines), the distal part of the pelvic fin (between 1st–5th soft rays) white for 1/3–1/2 of each ray length (lost after preservation), bands absent on the body in both fresh and preserved specimens, a smaller orbit diameter (11.4–12.4% of SL), a longer second dorsal fin spine (48.0–68.9% of SL), and shorter second and third anal fin spines (10.7–11.2% and 10.4–11.3% of SL), respectively.     

<Emphasis Type="Italic">Careproctus parvidiscus</Emphasis>, a new species of liparid fish (Teleostei: Scorpaeniformes) collected from the southern Okhotsk Sea,Japan

 A new liparid, Careproctus parvidiscus, is described on the basis of a single specimen (177 mm in standard length) collected from the southern Okhotsk Sea, off Shiretoko Point, Hokkaido, Japan, at 400–700 m depth. It is distinguished from other congeners by the following combination of the characters: 50 dorsal fin rays, 44 anal fin rays, 10 + 47 = 57 vertebrae, 2 pleural ribs, 14 pyloric caeca being slender and pointed, 2 suprabranchial pores, narrower gill opening, longer lower lobe of pectoral fin, base of uppermost pectoral fin ray almost on a level with center of eye, rudimentary disk, dusky peritoneum, and black stomach. Received: June 13, 2001 / Revised: December 7, 2001 / Accepted: December 22, 2001     

Hermaphroditism in Meloidogyne hapla

Hermaphrodites were detected in diploid and polyploid isolates of population 86-Va of Meloidogyne hapla. Young hermaphrodites are indistinguishable from normal females. Initially, hermaphrodite ovaries are filled with oocytes at various stages of development. Hermaphroditism is expressed later when young oocytes in the early pachytene region of the growth zone suddenly advance to diakinesis and proceed with maturation divisions, resulting in spermatid production. Spermatogenesis may be initiated shortly after the fourth molt, or later, after a female has produced some eggs. Spermatogenesis may occur in one or both gonads, and it may be initiated in one gonad before the other. Once initiated, spermatogenesis continues for the entire reproductive life of the hermaphrodite. Several thousand spermatozoa accumulate in the ovotestis. Because they do not pass through the oviduct into the spermatotheca, they do not take part in reproduction (nonfunctional hermaphroditism). Among the progeny of hermaphrodites, ca. 50% are hermaphroditic, and the remainder are apparently normal females which, however, produce about 50% hermaphroditic progeny. Two temperature regimes (20-23 C and 27-30 C) did not influence the percentage of hermaphrodites among the progeny. Hermaphroditism could not be transmitted to nonhermaphroditic isolates following attempted crosses between males of hermaphroditic and females of nonhermaphroditic isolates. Although this result suggests cytoplasmic rather than nuclear inheritance, this conclusion is not definitive.     

A new species of the morid genusgadella (teleostei: gadiformes) from the galápagos islands

A new species of deepwater morid fish,Gadella thysthlon, is described on the basis of five specimens from the Galápagos Islands. It differs from other species ofGadella by its low dorsal and anal fin ray counts (8+56–58 and 64–66 respectively), moderate number of gill rakers (4–5+9–11), small luminous organ that is closer to the anus than the interventral line, and its dark body, bright red-orange median fins with dark bases, and melanophores on the tongue apex and the palatal midline.     

Annual reproductive cycle and sexual dimorphism in the dragonet,repomucenus valenciennei, in tokyo bay, japan

The annual reproductive cycle of the dragonet,Repomucenus valenciennei, from Tokyo Bay, Japan, was studied by analysis of seasonal trends in gonadosomatic indices and histological observations of gonads. Sexual dimorphism in the growth of several body parts relative to standard length (SL) and changes in color pattern of the first dorsal fin with growth were also investigated. The spawning season lasted from spring (April [1991] or February [1992]) to autumn (October) with two spawning peaks, in spring and autumn. In spring, only one-year-old (age 1+) fish spawned, age 0+ females not spawning until autumn, at which time they had reached age 1+. Likewise, histological observations of males indicated that testes had reached full maturity by 80 mm SL (age 1+). The minimum mature size of females was estimated as 60 mm SL. In males 45–80 mm SL, the first spine of the first dorsal fin, last ray of the second dorsal fin, last ray of the anal fin, and caudal fin ray showed strongly positive allometry, indicating rapid growth of these structures relative to SL. Subsequently, their growth returned to an isometric pattern in males>80 mm SL. In females, on the other hand, the same body parts showed slightly positive allometry throughout their growth. The color pattern on the first dorsal fin also changed in males 45–80 mm SL.     

Larval and juvenile Polymetme elongata (Stomiiformes: Phosichthyidae) collected from Suruga Bay and offshore waters, Japan

Two larvae [17.4 mm standard length: SL (postflexion stage)] and 26.1 mm SL (transformation stage)] and a juvenile (31.7 mm SL) of a phosichthyid, Polymetme elongata, from Suruga Bay and offshore waters, central Japan, are described. These specimens had an elongate body with relatively short preanal length (53–63% SL), long anal fin base (2.6–3.4 times dorsal fin base length), and anal fin origin below dorsal fin base, and were further characterized by a blackish flap on each eye and internal clusters of melanophores (e.g., along caudal myosepta around midlateral line and on ventral margin of caudal peduncle). The short preanal length and larval melanophore pattern were very similar to those of another phosichthyid, Yarrella blackfordi, from the Atlantic Ocean.     

Ultrastructural characterization of the gonads of Triops cancriformis (Crustacea, Notostraca) from populations containing both females and males: no evidence for hermaphroditic reproduction

 The gonads of female and male Triops cancriformis specimens from populations of the northern part of the species distribution area were examined by conventional transmission electron microscopy in order to gain insight into the complicated reproductive mode of the species. Ovarian follicles consisted of an oocyte and three nurse cells and were surrounded by a thin layer of follicular cells. Oocytes are initially smaller than nurse cells and contained mitochondria of the cristae type as well as many free ribosomes. The prominent nucleus contained a nucleolus. The cytoplasm of oocytes was filled with yolk globules that were surrounded by membranes of the endoplasmic reticulum. Nurse cells also contained yolk globules. The follicle duct walls consisted of closely packed elongated cells covered by a lamellar basal lamina. No distinct Golgi apparatus was found in the follicle duct cells. The passage of oocytes through the duct was accompanied by a marked flattening of the follicle duct cells. Simultaneously, the oocytes were wrapped in eggshell material before entering the longitudinal oviduct. Testicular lobes were not found in any of the investigated female specimens. In male animals, the epithelial wall of the testicular tubules consisted of both germinal and vegetative cells. Maturing spermatids formed multicellular nests located in clearly delimited cysts in the intercellular space of the testicular epithelium. The lumen of the testicular tubules contained, exclusively, free mature spermatozoa. These characteristics point to the cystic type of spermiogenesis. Mature spermatozoa were non-flagellate, had a regular ovoid shape of 4–5 μm diameter, and an acrosome was not found. Only a negligible amount of spermatozoa (< 5%) showed signs of degeneration. In conclusion, the results provide evidence for a parthenogenetic and/or bisexual reproduction mode rather than a hermaphroditic one in the populations examined. Accepted: 4 August 1997     

A larva of Coryphaenoides pectoralis (Gadiformes: Macrouridae) collected by deep-sea submersible from off Hokkaido, Japan

A late-stage larva of Coryphaenoides pectoralis was first observed in situ and subsequently collected by the deep-sea submersible “Shinkai 2000” from mesopelagic waters at a depth of 530 m off Hokkaido, Japan. The larva (14.5 mm in head length, 149+ mm in total length) has fan-like pectoral fins, elongate first dorsal fin, pelvic fin and tail, 10 first dorsal rays (including 2 pseudospines), and 7 pelvic fin rays, 6 branchiostegal rays, no light organ, anus just anterior to anal fin origin, 2 retia and gas glands, 14 abdominal vertebrae, and previously reported larval pigmentation. Counts of second dorsal and anal fin rays, and caudal vertebrae, are reported for the first time.     

Microdontochromis rotundiventralis, a new cichlid fish (perciformes: Cichlidae) from Lake Tanganyika

Microdontochromis rotundiventralis, a new species of cichlid fish, is described on the basis of 13 specimens from Nkumbula Island, Lake Tanganyika (Zambia). It is distinct from its only congener,M. tenuidentatus, in having two (rarely one) rows of teeth on both jaws, a rounded distal margin on the pelvic fin, the outermost pelvic fin soft ray length 1.23–1.43 times the innermost ray, a deeper body (depth 26.8–29.1% standard length) and the anal fin with 9 (rarely 8 or 10) soft rays.     

Development of eggs, larvae and juveniles of laboratory-reared blue whiting,Sillago parvisquamis (Percoidei: Sillaginidae)

The embryonic, larval and juvenile development of blue whiting,Sillago parvisquamis Gill, are described from a series of laboratory-reared specimens. Mean egg diameter and mean total length (TL) of newly-hatched larvae were 0.71 mm and 1.58 mm, respectively. The eggs were non-adhesive, buoyant and spherical with an oil globule (mean diameter 0.18 mm). Hatching occurred about 20 hours after fertilization at a temperature of 24.0–25.0°C, newly-hatched larvae having 38–40 myomeres. The yolk and oil globule were completely absorbed 3 days after hatching at 2.8–3.2 (mean 3.0) mm TL. Notochord flexion was completed by 7.2–8.2 (7.7) mm TL, and pectoral and caudal fin rays fully developed by approximately 10 mm and 8.5 mm TL, respectively. Completion of fin development occurred in the following sequence: caudal, pectoral, anal and second dorsal, first dorsal and pelvic, the last-mentioned by approximately 11 mm TL. The larvae ofS. parvisquamis andS. japonica, which closely resemble each other in general morphology and pigmentation, could be distinguished as follows. Newly-hatchedS. parvisquamis larvae had more myomeres thanS. japonica (38–40 vs. 32–34) and more melanophores on the dorsal surface of the body (19–28 vs. about 40).Sillago japonica had a vertical band of melanophores on the caudal peduncle, which was lacking in postflexionS. parvisquamis larvae. In addition, juveniles ofS. parvisquamis (larger than 23 mm TL) had melanophores on the body extending anteriorly to below the lateral line to form a midlateral band, whereas no obvious band occurred on similarly-sizedS. japonica juveniles.     

Rhodeus pseudosericeus sp. nov., a new bitterling from South Korea (Cyprinidae, Acheilognathinae)

A new bitterling, Rhodeus pseudosericeus sp. nov., is described on the basis of 31 specimens from five localities included in the Namhan River system, South Korea. The new species is distinguished from other Rhodeus species by the following combination of characters: branched dorsal fin rays 9–10 (mode 9); branched anal fin rays 9–11 (mode 10); longest simple ray of dorsal fin strong and stiff, distally segmented; pelvic fin rays i, 6–7; iris of males blackish; dorsal and anal fins of males grayish in breeding season; karyotype with 2n = 48 (8m + 20sm + 20st). Rhodeus pseudosericeus sp. nov. is similar to Rhodeus sericeus sericeus in the number of pelvic fin and branched dorsal fin rays and the melanophores present on the dorsal fin membrane, but differs from the latter in having a greater body depth, more branched anal fin rays, fewer vertebrae, a lower number of scales in the lateral series, and differing male nuptial coloration. Received: June 30, 2000 / Revised: February 21, 2001 / Accepted: March 6, 2001     

Induction of ovarian maturation and development of eggs,Larvae and Juveniles of the Puffer,Takifugu exascurus,Reared in the Laboratory

Ovarian maturation of the pufferTakifugu exascurus (Jordan et Snyder) was induced, and embryonic, larval and juvenile development was observed. The brood fish were collected in Tassha Bay, Sado Island (38°05′N, 138°15′E), during the spawning season in 1986 which seemed to extend from late June to mid-July. To each female 3 mg acetone-dried pituitary ofHypophthalmichthys molitrix was injected to induce ovarian maturation, which took place in about 77 hours at a water temperature of 19.5–21.0°C. The eggs obtained by hormone injection were artificially fertilized with the milt from a collected male. The hatched larvae were fed successively on rotifersBrachionus plicatilis, Artemia nauplii and minced fish meat, and reared for a period of about one year. The eggs were spherical, 1.24±0.04mm in diameter, demersal and adhesive. The egg-membrane Was transparent and yolk was orange in color, containing a cluster of small oil-globules. The incubation period was about 160 hours at a water temperature of 18.5–21.0°C. The newly-hatched larvae, measuring 2.9– 3.1 mm TL, had 8+15 = 23 myomeres. Absorption of the yolk was completed 3 days after hatching, by which time the larvae had attained 3.5–3.6 mm TL. Larval finfolds disappeared and rudimentary dorsal, anal and caudal fins formed at 4.1–4.4 mm TL, in 6 days after hatching. In 9-day old larva (5.4 mm TL), fin ray rudiments appeared on the dosai, anal and caudal fins and spine-like scale formed on the belly. In 16-day old specimens, 9.1–10.2 mm TL, the full complements of fin rays were completed on all the fins and the fish reached the juvenile stage. The growth of larvae and juveniles reared in 1986–1987 is expressed by the following equations, where y is total length (mm) and x is days after hatching. y₁ = 2.9420· 1.0639^x 0 ≦ x ≦ 19 (r = 0.998) y₂ = 4.0286· 1.0464^x 19≦ x ≦ 33 (r = 0.998) y₃ = 9.8854· 1.0180^x 33 ≦ x ≦ 72 (r = 0.996) y₄ = 20.1555· 1.0080^x 72 ≦ x ≦ 115 (r = 0.998) y₅ = 28.0610· 1.0049^x 115 ≦ x ≦ 202 (r = 0.995)     

A new genus and species of prickleback (Perciformes: Stichaeidae) from Japan

A stichaeid fish, Xenolumpenus longipterus gen. et sp. nov., is described on the basis of 2 specimens (107.1–114.9 mm in standard length) collected from 167 to 300 m in the northern Sea of Japan off southern Hokkaido, Japan. Xenolumpenus is unique among all known genera of the subfamily Lumpeninae in having all pectoral, pelvic, and anal fin rays elongate and unbranched with fin membranes well-incised. Xenolumpenus longipterus can be further distinguished from all species of the subfamily in having the following combination of characters: dorsal fin XLVI–XLVIII; anal fin II, 28–29; pectoral fin 11; large black blotches on pectoral fin; and black ocellus on caudal fin.     

The effects of induced masculinization on reproductive and aggressive behaviors of the female mosquitofish,Gambusia affinis affinis

Synopsis FemaleGambusia affinis affinis were masculinized with the degraded products of 65% stigmastanol-30% B-sitosterol, a phytosterol. The masculinized females were paired with non-treated males, non-treated females, and other masculinized females. The pairs were analyzed for reproductive and aggressive behaviors exhibited. The behavioral patterns of these pairs were compared statistically to the behavior patterns of the following non-treated pairs: male with male, female with female, and male with female. The masculinized females behaved like males in that they followed, swung, and thrust their gonopodia at non-treated females and larger masculinized females. However, the male-like behavior of the masculinized females was not as intense as that of normal males. Also, the effect of masculinization on the behavior of the treated female was context-dependent as seen when placed with a male or a smaller masculinized female. Under these conditions the masculinized females behaved like typical females and exhibited no masculinized behaviors. The effects of anal spots and size differences are discussed as possible explanations for the variability in behaviors exhibited. The masculinized females displayed no change in aggressive behaviors.     

<Emphasis Type="Italic">Dolichopteryx pseudolongipes</Emphasis>, a new species of spookfish (Argentinoidei: Opisthoproctidae) from the eastern Pacific Ocean

A new species of opisthoproctid, Dolichopteryx pseudolongipes, is described on the basis of three specimens (48.7–79.9 mm in standard length: SL) collected from the eastern Pacific Ocean. This species is characterized by small tubular eyes (diameter 2.7–3.9% SL), presence of an adipose fin, anal fin base originating under the dorsal fin base, relatively short predorsal (73.3–73.8% SL), prepelvic (64.3–67.9% SL), preanal (77.4–80.1% SL), and preanus (71.5–75.7% SL) lengths; 31–33 (=9–10 + 22–24) gill rakers and 43–45 vertebrae. Although D. pseudolongipes had previously been confused with Dolichopteryx longipes, many differences between the species are apparent [e.g., adipose fin absent, anal fin base origin just behind dorsal fin base, greater prepelvic length (70.3–72.7% SL), 25 gill rakers, and 46–47 vertebrae in D. longipes].