Unusual morphological and ecological characteristics of hyperbenthic juveniles of Gobius cruentatus

Unidentified hyperbenthic gobiid juveniles were collected while SCUBA diving at Oštro, in the Kvarner area, northern Adriatic Sea from 1996 to 2000. An additional 23 specimens of this form were collected at Oštro on 13 May 2002. They were kept alive and reared in the aquarium. Groups of specimens were sacrified periodically to study changes in morphology and growth. From the data acquired the hyperbenthic juveniles were identified as those of the red‐mouthed goby Gobius cruentatus . The present findings provide data on the unusual morphology and ecology of G. cruentatus juveniles.     

Two species of goby, Boleophthalmus pectinirostris and Scartelaos sp., as the new second intermediate hosts of heterophyid fluke in Korea

A survey was performed in order to determine the infection status of the metacercariae of heterophyid fluke in two goby species, Boleophthalmus pectinirostris and Scartelaos sp., collected from Gangjin-gun, and Shinangun, Sooncheon-shi, Jeollanam-do, Republic of Korea. A total of three metacercariae of Heterophyopsis continua was found in only one B. pectinirostris (10.0%) from Gangjin-gun. Heterophyes nocens metacercariae were detected in 24 B. pectinirostris (96.0%) and 14 Scartelaos sp. (63.6%) from Shinan-gun. Heterophyopsis continua metacercariae were found in 11 B. pectinirostris (44.0%) and 21 Scartelaos sp. (95.5%) from Shinan-gun. Stictodora fuscata metacercariae were detected in 18 B. pectinirostris (72.0%) from Shinan-gun. No metacercariae were detected in 20 B. pectinirostris from Sooncheon-shi. From the above results, this study is the first to prove that B. pectinirostris and Scartelaos sp. serve as the second intermediate hosts of some heterophyid flukes in Korea.     

Einnischung von fünf Grundeln (Teleostei, Gobiidae) der Ostsee und ihre Deutung mit Hilfe der Präadaptationstheorie

Niche occupation by 5 goby species (Teleostei, Gobiidae) in the Baltic Sea and its interpretation by means of the theory of pre-adaptation The habitats and prey of five goby species were investigated near the shore of the Lübeck Bight (SW Baltic) during the period 1989–1991. Observations showed that Gobius niger is a macrobenthos feeder, Pomatoschistus microps a meiobenthos feeder; Pomatoschistus pictus prefers meiobenthos as well as plankton while Pomatoschistus minutus feeds on benthos of every size, as well as planktonic cope-pods when offered in surplus; Gobiusculus flavescens is generally a plankton feeder but, when this component is in short supply in the summer, changes to macrobenthos. P. pictus and P. microps existed at different depths; G. flavescens and P. minutus presented countercurrent densities in shallow habitats during the course of a year. This adaptability of behaviour in habitat and prey choice can be explained by the modification ability of pre-adaptional genes in the goby genomes. After having invaded species-poor habitats such as the brackish Baltic Sea, wide niche dimensions are initially occupied. The niche is here considered to be an attribute of the species as well as of the habitat according to GÜNTHER (1950). Hence, innidation is defined as a process which implies specialization by loss of most preadaptations and leads to the optimal use of the ecosystem by the species. This process of a single species corresponds to the maturation of successions of whole biocoenoses.     

Breeding sounds of male Padogobius nigricans with suggestions for further evolutionary study of vocal behaviour in gobioid fishes

The male Arno goby Padogobius nigricans courts ripe females by emitting sounds at a high rate, mainly from the nest hollow. Laboratory observations revealed that each sound is an almost pure tone wave showing marked amplitude modulation and decrease of frequency throughout its length. The mean tone frequency averaged 79.4 Hz and the sound duration averaged 327 ms. Both these sound parameters were significantly affected by the temperature of the water. Acoustic behaviour during sexual interactions was compared for tank-confined males and males from a community group. The fact that acoustic activity of the male peaked when the female stayed motionless at the nest entrance suggested that the sound emitted by the male P. nigricans has a role as an advertising signal. Observation of spawning behaviour showed the emission of sounds by the male rapidly diminished and eventually ceased shortly after the beginning of oviposition. Thus, the male sound seems not to be a functional component of the spawning behaviour. Finally, data on vocal behaviour of this species were examined within a comparative framework, also taking into consideration phylogenetic relationships between Italian freshwater gobies.     

Sound production in the Ponto‐Caspian goby Neogobius fluviatilis and acoustic affinities within the Gobius lineage: implications for phylogeny

The aim of this study was to describe the vocal repertoire of the Ponto‐Caspian goby Neogobius fluviatilis and to compare the acoustic properties of this species with those of other soniferous Mediterranean gobies belonging to the Gobius lineage. Vocalizations and associated behaviours were recorded under controlled aquarium conditions in female and male N. fluviatilis. Sound emission was elicited by means of ‘intruder tests’, using an individual of the same or opposite sex as an intruder, and recording sounds using a hydrophone placed 20 cm from the shelter used as a nest for the resident fish. Five acoustic properties, including spectral and temporal properties, were measured from 13 individuals. The vocal repertoire of the species consisted of sequences of short vocalizations during both agonistic and reproductive intraspecific interactions. The wave form of each sound resolved in a pure sine wave composed of rapidly repeated pulses. Sounds lasted about 200 ms, showing an average fundamental frequency of about 80 Hz. Sound properties did not differ between reproductive and the aggressive contexts, and the general structure of sounds was highly stereotyped. The individual means of three acoustic independent traits characterizing the sounds of seven species of the Gobius lineage, including N. fluviatilis, were then entered in a discriminant function analysis to assess how well species could be differentiated on the basis of acoustics, and their degree of affinities. The results suggested that the pulse repetition rate of the sounds, i.e. the relative tonal/pulsatile nature of the sounds, was the most important property in differentiating the species, and that this trait may contain a high level of phylogenetic signal, as the species producing tonal sounds clustered together, in line with the results of recent molecular phylogenic studies. The results were discussed in light of the geological and phylogeographical events believed to have driven the diversification of European gobies.     

A new species of Gobius (Perciformes: Gobiidae) from the Mediterranean Sea and the redescription of Gobius bucchichi

A new species of the gobiid genus Gobius (Gobiidae, Perciformes), Gobius incognitus sp. nov. is described from the Mediterranean Sea, and its most morphologically similar species Gobius bucchichi is redescribed. The new species is distinguished from its congeners by: scales in lateral series 51–59; predorsal scales 25–35; opercle scaled in adults with 10–16 scales present; pectoral fin with ray count 18–20 and free tips on upper rays well developed and on the first ray longer than two thirds of the entire ray length; pelvic disc complete and with well‐developed anterior membrane without lateral lobes; anterior oculoscapular canal with pore α at rear of orbit; oculoscapular row x¹ not extending forwards to pore β; suborbital row d discontinuous with large gap below suborbital rows 3 and 4; eye diameter 1·08–1·32 in snout length; by pigment rows on cheek and pigmentation on pectoral‐fin base.     

Sex change in either direction by growth-rate advantage in the monogamous coral goby, Paragobiodon echinocephalus

The size-advantage model predicts the evolution of sex changeif the relative reproductive success of the sexes changes withsize or age. In the goby (Paragobiodon echinocephalus) the largesttwo fish, a male and a female matched by size, breed monogamouslyin each host coral. Because the female fecundity and male abilityof egg care increase with body size in a similar way, no size-fecundityadvantage exists. However, we found both protogyny and infrequentprotandry in a natural population of this species in Okinawa.New pairs were often formed after movement between host coralsand also sex change or sex differentiation of one or both members.In most new pairs males were larger than females, and femalesgrew much faster than their mates until breeding (growth-rateadvantage). The smaller member of a new pair should be the femalethat grows faster, because the smaller limits the reproductivesuccess of the pair. To form such a pair, the goby changed sexaccording to the sex and relative size of a new mate, as a status-dependentconditional strategy. The growth-rate advantage predicts predominanceof protogyny, but movement between host corals provides opportunitiesalso for protandry.     

Pharyngeal jaw morphology and homology in Sicydiine Gobies (Teleostei: Gobiidae) and allies

An extremely large number of fifth ceratobranchial teeth, with highly modified, striated, and hooked tips were observed in the central and western Pacific sicydiine goby genus Stiphodon.A scanning electron microscopic study of the form and arrangement of fifth ceratobranchial teeth was conducted to assess the distribution of these modifications in sicydiine gobies and their putative close relatives. Our goals were to explore a new set of characters in gobioid systematics, to test sicydiine monophyly, and to test hypotheses of relationships of sicydiine gobies. Sicydiines are hypothesized herein to be most closely related to the western Pacific Tukugobius and Rhinogobius,freshwater genera with which they share thickened pelvic-fin rays, no teeth on the anterior portion of the fifth ceratobranchial bones, fifth ceratobranchial teeth with differentiated and striated tips, and overlapping anterior rami of the fifth ceratobranchial bones. The latter two characters occur in some, but not all, sicydiines. The pantropical freshwater goby Awaous,often classified with sicydiines, is not considered the closest relative of the subfamily. The highly modified fifth ceratobranchials of Stiphodon are similar to, and concluded here to be homoplasious with, those of the mudflat-dwelling New World goby Evorthodus and the Indo-west Pacific oxudercine gobies, represented in this study by Pseudapocryptes. J. Morphol. 237:257–274, 1998. Published 1998 Wiley-Liss, Inc.     

云南滇池入侵虾虎鱼类的共存策略

虾虎鱼类是入侵种的一个重要来源,常数种共同入侵同一区域,其种间如何实现共存是当前鱼类入侵生态学的一个重要科学问题。本研究通过形态分析、空间分布调查及摄食分析等方法,从形态分化和生态位分化角度揭示滇池新入侵的粘皮鯔虾虎鱼与先期入侵近缘种的共存策略。结果表明: 粘皮鯔虾虎鱼与小黄黝鱼、子陵吻虾虎鱼、波氏吻虾虎鱼等先期入侵种在形态上存在显著差异。其空间分布在研究区域上与上述物种存在显著差异,空间生态位指数显著高于其余物种。摄食分析显示,粘皮鯔虾虎鱼的食物多样性指数显著高于其余物种;其主要摄食种类为圆形盘肠溞和腺介虫等,与其他虾虎鱼类主要摄食种类也存在明显差异。在摄食生态位上,滇池入侵虾虎鱼类存在显著分化。这说明形态差异、空间生态位分化及营养生态位分化降低了种间竞争强度,促进了粘皮鯔虾虎鱼与先期入侵虾虎鱼类实现共存。粘皮鯔虾虎鱼可能凭借摄食策略上的优势在种群数量、占据栖息地范围上优于竞争对手,成为研究区域入侵虾虎鱼类中的优势种群。     

A cornucopia of cryptic species - a DNA barcode analysis of the gobiid fish genus Trimma (Percomorpha,Gobiiformes)

A genetic analysis of partial mitochondrial 5’ cytochrome c oxidase I gene (DNA barcode) sequences of 473 specimens assigned to 52 morphological species (including four known, but not formally named, species) of the gobiid genus Trimma revealed the presence of 94 genetic lineages. Each lineage was separated by > 2% sequence divergence. Thus there were an additional 42 haplogroups recognizable as provisional candidate species given that a value of > 2% difference is typical of different species of fishes. Such a high degree of apparently different cryptic species is, in our experience, virtually unprecedented among vertebrates. These results have precipitated further morphological research in a few cases, which has uncovered subtle differences independently corroborating the genetic results. However, such efforts are limited by the dearth of traditional systematists available to undertake the necessary time-consuming, and highly detailed, morphological research. In some cases, the genetic results we present are consistent with, and confirm, minor taxonomic distinctions based on morphology and/or colour pattern. In other instances, what had been recognized as a single species consists of several genetic lineages - up to eight in, for example, what we have identified based on morphology as Trimma okinawae. The increase from 52 to 94 potential species in our sampling raises the predicted total number of species in this genus from about 110 to nearly 200 (versus the 73 valid described species currently recognized).