<Emphasis Type="Italic">Trichiurus nickolensis</Emphasis>, a new hairtail from Australia belonging to the <Emphasis Type="Italic">Trichiurus russelli</Emphasis> complex (Perciformes: Trichiuridae)

A new hairtail, Trichiurus nickolensis, is described on the basis of ten specimens collected off northwestern Australia, off the Northern Territory, and in the Gulf of Carpentaria, Queensland. The new species strongly resembles T. brevis Wang and You in Wang et al., 1992, off Hainan Island, South China Sea, and T. russelli Dutt and Thankam, 1966, off the Waltair Coast, Andhra Pradesh, India, in having the highest point of the supraoccipital crest situated directly above the posterior margin of the eye and a relatively short caudal peduncle. Trichiurus nickolensis differs from those two species in being strongly pigmented on the anterior section of the dorsal fin membrane (vs. slightly pigmented), and having a dorsal head margin that appears concave in lateral view, rises gently from snout tip to above middle of orbit, and then extends more steeply to dorsal fin origin (vs. rising gently from tip of snout to dorsal fin origin). The new species also has a greater number of dorsal fin rays (III, 138–143 vs. III, 127–132 and III, 127–131 in T. brevis and T. russelli, respectively) and total vertebrae (160–166 vs. 147–155 and 149–153), and shorter preanal length (mean 30% TL vs. 33% TL and 35% TL), head length (11% TL vs. 12% TL and 13% TL) and upper jaw length (4% TL vs. 5% TL and 5% TL).     

Early life history of a seahorse, Hippocampus mohnikei, in Tokyo Bay, Japan

The early morphological development, seasonal and spatial occurrence patterns, and food habits of a seahorse, Hippocampus mohnikei, in offshore waters of Tokyo Bay, central Japan, were studied on the basis of 206 juvenile and young specimens (6.0–65.3 mm TL) collected between August 1995 and January 1999. All the specimens were collected within the period from May to January, inclusive, each year. In the least developed specimen (6.0 mm TL), the number of dorsal, anal, and pectoral fin rays had attained the adult complement, whereas the minute caudal fin, consisting of two rays, was present in juveniles of 6.0–26.4 mm TL. Hippocampus mohnikei≧35 mm TL, being larger than settlement size (ca. 30 mm TL), had very low gut fullness index values (GFI = 0, >70% of specimens), whereas those of 15–29 mm TL had higher values (GFI = 2–4, >80% of specimens). In addition, larger individuals selectively fed on larger planktonic animals (species of Brachyura), which occurred naturally at low densities, although smaller food items, such as Oithona davisae and Penilia avirostris, occurred abundantly, being consumed by smaller H. mohnikei individuals (15–34 mm TL). These results indicated that food availability for H. mohnikei in offshore waters of Tokyo Bay is significant for individuals larger than settlement size, because their food preference would shift from smaller food items to larger food items, which would be scarce in their environments. Received: January 12, 2001 / Revised: May 13, 2001 / Accepted: June 14, 2001     

New species of the eel genera Dysomma and Dysommina from Vietnam,South China Sea (Anguilliformes: Synaphobranchidae)

Two new cutthroat eel species are described from Vietnam. Dysomma intermedium sp. nov. has a relatively long trunk, being about half of head length and anal-fin origin more than twice pectoral-fin length behind the pectoral-fin tip; pectoral fin well developed; dorsal-fin origin over or slightly in front of base of pectoral fin; two intermaxillary teeth; four or five compound teeth on ethmovomer; single row of seven or eight teeth on lower jaw; total lateral-line pores 70–76; and 21 pre-anal and 118–124 total vertebrae. Dysommina brevis sp. nov. differs from congeners by having a trunk shorter than head length, its length 11.1%–11.8% TL; a short pre-anal length 24.6%–25.6% TL, eye diameter 11.8%–12.3% head length; three large and one or two small teeth on ethmovomer; and fewer teeth on the upper and lower jaws. In addition, a specimen representing the first record of Dysommina orientalis in Vietnamese water is documented.     

A new species of Petroleuciscus (Teleostei: Cyprinidae) from the Büyük Menderes River,southwestern Anatolia,Turkey

Petroleuciscus ninae sp. nov. is described from the Büyük Menderes River drainage. The new species is distinguished by having a black lateral stripe from head to base of caudal fin, stripe distinct anteriorly and posteriorly, wider than eye diameter; numerous black pigments on anal‐fin rays; body depth at dorsal‐fin origin 27–30% standard length (L_S); head width at posterior margin of eye 16–19% L_S; and eye diameter smaller than snout length. Petroleuciscus ninae is also distinguished from other species in adjacent waters by having six fixed diagnostic nucleotide substitutions in the mitochondrial DNA coI barcode region.     

Swimming performance of adult bighead carp Hypophthalmichthys nobilis (Richardson, 1845) and silver carp H. molitrix (Valenciennes, 1844)

Although the movement of invasive bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix) in the Upper Mississippi River system is dependent on their ability to swim through its numerous lock‐and‐dams, the swimming performance of adults of these species is at present unknown. Using a large (2,935‐L) mobile swim tunnel, the swimming performance of adult bighead and adult silver carp was quantified at water velocities that challenged them to exhibit either prolonged and/or burst swimming (76–244 cm/s) with fatigue times of less than 10 min. Simple log‐linear models best described the relative swim speed to fatigue relationships for both species. Under these conditions, the swimming performances of adult bighead and silver carp were similar to several species of adult fishes native to the Mississippi River system, but relatively low (<3 total body lengths per second, TL/s) compared to previously studied juveniles and sub‐adult bigheaded carps (3–15 TL/s). The decline in endurance with water velocity was three times greater in bighead carp (slope = ?2.98) than in silver carp (slope = ?1.01) and the predictive ability of the bighead model was appreciably better than the silver carp model. The differences in adult swimming performance between the two species were coincident with behavioral differences (e.g. breaching in silver carp but not in bighead carp). The swimming performance data of adult bighead and silver carp can now be used to evaluate whether their passage through manmade river structures including the gates of lock‐and‐dams in the Upper Mississippi River might be reduced.     

<Emphasis Type="Italic">Microrasbora</Emphasis> Annandale,a new genus record in China,with description of a new species (Teleostei: Cyprinidae)

A new species of genus Microrasbora Annandale (1918), M. microphthalma, is described from the Nanwan River, a tributary of the Ruili River, Irrawaddy drainage, in southwest Yunnan province, China. This new species is the first record of the genus Microrasbora in China. Microrasbora microphthalma can be distinguished from the other species of Microrasbora by the following combination of characters: 15–16 predorsal scales, eye diameter/head length 27–38%, eye diameter/interorbital width 70–93%, predorsal length/ standard length 60–68%, the preanal length/ standard length 65–71% and the origin of dorsal fin is posterior of that of the ventral fin. Xiao-Yong Chen and Jun-Xing Yang contributed equally to this paper.     

A new subspecies, Polynemus melanochir dulcis, from Tonle Sap Lake, Cambodia, and redescription of P. m. melanochir Valenciennes in Cuvier and Valenciennes, 1831 with designation of a neotype

 A poorly known threadfin, Polynemus melanochir Valenciennes in Cuvier and Valenciennes, 1831, is redescribed (as P. melanochir melanochir) on the basis of a newly designated neotype and a large number of specimens. Polynemus melanopus Sauvage, 1881 and 3 species commonly regarded as valid, Galeoides microps Steindachner, 1869, P. borneensis Bleeker, 1857, and Trichidion hilleri Fowler, 1905, are all considered junior synonyms of P. m. melanochir. In addition, a new subspecies, P. melanochir dulcis, is described on the basis of 3 specimens. Polynemus m. dulcis differs from P. m. melanochir in having a greater snout length [7% of SL vs. mean 6% (range 5–6%) of SL in the latter] and shorter upper caudal-fin lobe length [35% (34–35%) of SL vs. 39% (35–44%) of SL]. The former is currently known only from Tonle Sap Lake, Cambodia, whereas the latter is known from the Mekong River (Cambodia and southern Vietnam) and Kalimantan (=Borneo; Malaysia and Indonesia). Received: September 27, 2001 / Revised: December 20, 2001 / Accepted: December 29, 2001     

A new species, Trichiurus australis (Perciformes: Trichiuridae), from Australia

Trichiurus australis, a new trichiurid fish, is described on the basis of four specimens collected off Burnett River mouth, Pialba and Thursday Island, Queensland, Australia. The new species strongly resembles Trichiurus brevis Wang and You, 1992 (distributed in the South China Sea), T. russelli Dutt and Thankam, 1967 (the northwestern Bay of Bengal and the northern Gulf of Thailand), and T. nickolensis Burhanuddin and Iwatsuki, 2003 (northwestern Australia) in having the highest point of the supraoccipital crest situated directly above the posterior margin of the eye and being relatively small in size (less than ca. 700mm in total length: TL). It differs from those three species in having spinescent gill rakers almost with 2 equally long cusps [vs. (1, rarely 2 but 1 of them clearly shorter than another)], posterior caudal peduncle vertebrae bearing neural spines (vs. neural spines absent), longer caudal peduncle length (mean 16% TL vs. 6% in T. brevis, 8% in T. nickolensis, and 8% in T. russelli), and shorter precaudal length (83% vs. 93%, 91%, and 91%), preanal length (26% vs. 33%, 31%, and 35%), and head length (9% vs. 12%, 11%, and 13%). We have tentatively classified this new species under the Trichiurus russelli complex because the foregoing diagnostic characters are identical to this species complex except for the presence of neural spines in the posterior caudal vertebrae.     

Asterorhombus annulatus (Weber, 1913), a valid species distinct from Asterorhombus intermedius (Bleeker, 1865) (Pleuronectiformes: Bothidae)

Asterorhombus annulatus was long synonymized with A. intermedius. Twenty-nine specimens from the Coral Sea revealed that the former is clearly separable from the latter in having a short first dorsal fin ray, slender gill rakers with spinules, distinctly shorter blind-side pelvic fin base, an absence of conspicuous black spots on the ocular side of the body, greater eye diameter and greater interorbital width, and somewhat higher ranges of upper jaw lengths. A. annulatus is redescribed as a valid species. Received: March 4, 2000 / Revised: September 13, 2000 / Accepted: January 12, 2001     

Reproductive biology and length–weight relationship of painted comber, Serranus scriba (Linnaeus, 1758), in the Trogir Bay area (middle-eastern Adriatic)

The reproductive biology and sexual pattern of Serranus scriba (Linnaeus, 1758) were examined in the Trogir Bay area (middle‐eastern Adriatic) from June 2001 to May 2002. The total length (TL) of all observed specimens ranged from 7.1 to 20.0 cm; 50% of the population of this species sexually matured at 9.3 cm TL. Spawning took place from May to August, with a peak in June and July. Positive allometry was established in the length–weight relationship (b = 3.15).     

Age,growth, maturity and mortality of the tapetail anchovy Coilia brachygnathus (Engraulidae) in Lake Honghu,China

The tapertail anchovy Coilia brachygnathus, a commercially important species mainly distributed along the mid-lower Chang-Jiang basin, is by far the most dominant species in Lake Honghu. To figure out its success in this semiclosed lake, some basic biological parameters of this anchovy were analysed based on samples seasonally collected from October 2020 to December 2021. The results demonstrated that the age classes of fished individuals varied from 0.5 to 3.5, with the majority (97.36%) being between 0.5 and 3 years old. The size at 50% maturity of 17.2 cm total length (TL) for females and 19.0 cm TL for males corresponded to 1 and 1.6 years, respectively. Coilia brachygnathus has a short life span, early sexual maturity and a relatively fast growth rate. The flourishing of the fish in the lake is mainly attributed to its short life span, early maturity, fast growth rate, closed fishing, pelagic spawners, the availability of plenty of food and low predation effect on it. Age 3.5 year occurs in an extremely small percentage of the total (<3%), indicating that a large number of larger-sized or older fish died after spawning, which is probably one of the major sources of water pollution if the closed fishing measure is adopted in Lake Honghu. Thus, individuals older than 2 years or more than 20.0 cm TL should be harvested. These findings have important management implications for the fish resources in Lake Honghu and beyond.     

Small and valid species of Trichiurus brevis Wang and You, 1992 and T. russelli Dutt and Thankam, 1966, defined as the “T. russelli complex” (Perciformes: Trichiuridae)

 The taxonomic status of three small [probably less than ca. 600 mm in the largest total length (TL)] and poorly known species, Trichiurus brevis Wang and You, 1992 and T. minor Li, 1992, both from South China Sea, and T. russelli Dutt and Thankam, 1966, from Bengal Bay, was reexamined. Trichiurus brevis and T. russelli, being valid species, are redescribed and a neotype is designated for the latter. Trichiurus brevis is considered to be a senior synonym of T. minor, there being no significant differences in their type specimens. Both valid species, i.e., T. brevis and T. russelli, are similar to T. lepturus Linnaeus, 1758 (larger than ca. 1000 mm TL) in general appearance, but clearly differ from the latter in having the top of the supraoccipital crest situated directly above the posterior margin of eye (vs. well behind posterior margin), lower number of total vertebrae (147–155 and 149–153, respectively, in the former two species vs. 168–173 in T. lepturus), longer dorsal fin base (mean 87% and mean 84% vs. mean 76% of TL), and shorter caudal peduncle length (6% and 8% vs. 13% of TL). Furthermore, the former two species are characterized by having the anal fin origin situated below about the 32nd–35th dorsal fin ray base, whereas in T. lepturus it is situated below the 37th–41st dorsal fin ray base. We recognize that T. brevis and T. russelli together comprise a species group, defined as the “T. russelli complex,” in the genus Trichiurus, the two species differing in snout shape (strongly pointed in T. brevis vs. moderately pointed in T. russelli), snout length [mean 35% vs. mean 30% of head length (HL)], preopercle length (22% vs. 19% HL), predorsal length (70% vs. 63% HL), and dermal eye opening (16% vs. 18% HL). Received: April 26, 2001 / Revised: January 19, 2002 / Accepted: February 1, 2002     

A new species of the genus <Emphasis Type="Italic">Triplophysa</Emphasis> (Nemacheilinae: Balitoridae), <Emphasis Type="Italic">Triplophysa jianchuanensis</Emphasis> sp. nov,from Yunnan,China

A new loach species, named Triplophysa jianchuanensis, has been recognized in collections from Jianchuan in Dali Prefecture, Yunnan, China. Triplophysa jianchuanensis can be distinguished from the other Triplophysa species by the following combination of characteristics: smooth skin, scaleless; lateral line complete; head long (26.7–29.8% of SL); eyes large (25.9–31.0% of dorsal head length); snout shorter than postorbital length (26.9–30.1% of HL); middle of lower lip interrupted and forming a pair of furrows; lower jaw spoon-like with obtuse edge; posterior chamber of air bladder completely degenerated; intestines short, bending in zigzag-shape behind stomach; pelvic-fin tip not reaching anus; caudal fin emarginate; branched rays of dorsal fin 7; branched rays of caudal fin 16. A key to the known species of Triplophysa from the Lancangjiang River is provided.     

Pupil dilation and visual field in the piked dogfish, <Emphasis Type="Italic">Squalus acanthias</Emphasis>

The relatively large eye and pupil of the Piked Dogfish, Squalus acanthias, is visually arresting. However, knowledge of its basic visual characteristics lags far behind other areas in this generally well studied species. This study quantifies pupil dilation in a species that is naturally exposed to a broad range of light intensities and finds that the pupil area in the dark adapted state is 35.3% of the total eye area, an increase of 12.4% from the light adapted state. The anterior and posterior extents of the horizontal visual field are assessed and compared with both morphological and electrophysiological techniques and the results are integrated with the measured head yaw to derive the anterior convergence distance and blind area. The position of the eyes and the triangular, pointed snout of S. acanthias provides excellent anterior vision, which likely facilitates foraging upon its mobile prey.     

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     

Revision of the cyprinid genus Discogobio Lin, 1931 (Pisces: Teleostei) from the upper Red River basin in Wenshan Prefecture, Yunnan, China, with descriptions of three new species

The species of the genus Discogobio (Teleostei: Cyprinidae) inhabiting the Wenshan prefecture (branches of upper Red River) of Yunnan Province, China are reviewed. The authors recognize four species from the prefecture, Discogobio antethoracalis n. sp., Discogobio propeanalis n. sp., Discogobio poneventralis n. sp., and D. yunnanensis. D. antethoracalis and D. propeanalis had previously been identified as Discogobio brachyphysallidos. D. antethoracalis can be distinguished from D. brachyphysallidos by the following characters: snout rounded, not projected (versus slightly pointed, projected); head length 17.5–20.6% of SL (vs. 20.8–22.8); prepectoral length 16.3–18.3% of SL (vs. 19.1–22.0); interorbital width 52.5–60.9% of head length (vs. 44.7–50.0); anus to anal-fin origin distance 25% posterior end of pelvic-fin base to anal-fin origin distance (versus less than 25). D. propeanalis can be distinguished from D. brachyphysallidos by the following combination of characters: interorbital width greater than half of head length (versus less than half); pelvic-fin extending beyond anal-fin origin (versus not reaching anal-fin origin); anus closer to anal-fin origin, anus to anal-fin origin distance less than 25% posterior end of pelvic-fin base to anal-fin origin distance (versus more than 25%). D. poneventralis, with a small oral sucking disc (its posterior edge not reaching vertical of anterior margin of eye) is similar to Discogobio longibarbatus and D. macrophysallidos, but distinct from them in the following characters: rostral barbels equal to eye diameter (versus twice as long as eye diameter in D. longibarbatus); maxillary barbels not reaching posterior margin of oral sucking disc (versus beyond in D. longibarbatus); mid-ventral region anterior to pelvic-fin insertion scaleless (versus scaled in D. macrophysallidos); prepelvic length 57.1–58.1% of SL (vs. 52.4–55.6 in D. macrophysallidos); pectoral-pelvic length 40.8–41% of SL (vs. 32.6–35.9 in D. macrophysallidos); head length 17.5–18.4% of SL (vs. 19.8–21.8 in D. macrophysallidos); and snout length 44.9–47.2% of HL (vs. 48.9–55.4 in D. macrophysallidos).     

Length–weight and length–length relationships of fishes from the Ouémé River in Bénin (West Africa)

The relationships between total (TL) and standard (SL) lengths for 50 fish species and between TL and wet weight for 52 fish species caught in the Ouémé River are presented. Relationships between TL and SL are linear. Between TL and weight, the relationships are of the form TW = aTL^b. The b values range from 2.3307 to 3.5185. Student's t‐test revealed that 38.5% of the species have b values significantly different from 3.     

Ontogenetic shifts of heart position in snakes

Heart position relative to total body length (TL) varies among snakes, with anterior hearts in arboreal species and more centrally located hearts in aquatic or ground‐dwelling species. Anterior hearts decrease the cardiac work associated with cranial blood flow and minimize drops in cranial pressure and flow during head‐up climbing. Here, we investigate whether heart position shifts intraspecifically during ontogenetic increases in TL. Insular Florida cottonmouth snakes, Agkistrodon conanti , are entirely ground‐dwelling and have a mean heart position that is 33.32% TL from the head. In contrast, arboreal rat snakes, Pantherophis obsoleta , of similar lengths have a mean heart position that is 17.35% TL from the head. In both species, relative heart position shifts craniad during ontogeny, with negative slopes = −.035 and −.021% TL/cm TL in Agkistrodon and Pantherophis , respectively. Using a large morphometric data set available for Agkistrodon (N = 192 individuals, 23–140 cm TL), we demonstrate there is an anterior ontogenetic shift of the heart position within the trunk (= 4.56% trunk length from base of head to cloacal vent), independent of head and tail allometry which are both negative. However, in longer snakes > 100 cm, the heart position reverses and shifts caudally in longer Agkistrodon but continues toward the head in longer individuals of Pantherophis . Examination of data sets for two independent lineages of fully marine snakes (Acrochordus granulatus and Hydrophis platurus ), which do not naturally experience postural gravity stress, demonstrate both ontogenetic patterns for heart position that are seen in the terrestrial snakes. The anterior migration of the heart is greater in the terrestrial species, even if TL is standardized to that of the longer P. obsoleta , and compensates for about 5 mmHg gravitational pressure head if they are fully upright.     

Feeding habits of horse mackerel, Trachurus trachurus (Linneaus, 1758), from the central Adriatic Sea

The feeding habits of the horse mackerel, Trachurus trachurus, from the central Adriatic Sea were investigated with respect to fish size and season. Stomach contents of 1200 specimens 12.9–37.6 cm total length (TL) taken at monthly intervals (January–December 1995) were analyzed. Of the total number of stomachs examined, 597 were empty (49.7%). This percentage varied significantly with season; the maximum number of empty stomachs was observed during January (80%) and February (82%) and a minimum number observed during July (15%) and August (19%). A total of 30 different prey species belonging to five major groups: Crustacea (Euphausiacea, Mysidacea, Decapoda), Cephalopoda, and Teleostei was identified in the stomach contents. Euphausiids were the most important ingested prey in all seasons as well as in small‐ and medium‐size classes (<28 cm TL). Two species of euphausiids, Nyctiphanes couchii (%IRI = 36.0) and Euphausia krohni (%IRI = 12.9), were the most frequent prey. The proportion of teleosts in stomach contents increased with the increasing size class of horse mackerel and was 15.5% IRI in >30 cm TL individuals. The mean weight of stomach contents increased significantly for fish larger than 24.1 cm TL, while the mean number of prey items significantly declined in the large‐size classes.