Redescription of Pennella sagitta (Copepoda: Pennellidae) from Histrio histrio (Pisces) in the North-west Atlantic Ocean with a provisional review of the genus Pennella

Pennella sagitta (L.) is redescribed from fresh specimens recovered from Histrio histrio (L.) and from material in the collection of the Smithsonian Institution. A small, delicate parasitic copepod, P. sagitta is shown to be a valid species, found only on fishes of the family Antennariidae. Attempts of earlier workers to synonymize P. diodontis with P. sagitta are rejected, and the distinguishing features of both species are presented. A neotype is proposed from material described herein, due to a lack of the original holotype. A provisional review of the genus Pennella Oken, 1816 is provided, and the taxonomic status of 31 species is discussed. Pennella exocoetus is described from material in museum collections. Seven species, P. balaenoptera, P. diodontis, P. exocoetus, P.filosa, P. instructa, P. makaira and P. sagitta are considered as valid members of the genus. The remaining species are reduced to synonymy with valid species or accorded the status of species inquirendae.     

珠江口棘头梅童鱼耳石的生长特性

研究了棘头梅童鱼(Collichthys lucidus)耳石的形态参数、生长特性及其与鱼体生长的关系,选用左矢耳石为研究对象,用直线、对数、多项式、幂函数和指数函数拟合矢耳石各参数的生长关系式,依据耳石日轮鉴定了日龄。结果表明,体长范围为29.8～104.0 mm的棘头梅童鱼矢耳石的长直径随鱼体生长而增大,但短直径与长直径的比值以及长直径方向上的短半径与长半径的比值则基本稳定。矢耳石的长、宽和重之间,以及长半径和短半径之间均呈显著的幂函数相关关系;矢耳石生长与鱼体生长的关系中,矢耳石长、宽、厚、重与长半径和体长、体重之间的关系,除了体长与耳石厚的关系为显著的二次多项式外,全部呈显著的幂函数相关关系。     

骨唇黄河鱼耳石早期形态发育和轮纹特征研究

研究了骨唇黄河鱼仔稚鱼耳石在实验室养殖条件下的发育过程和生长特点,确证了轮纹沉积规律。结果表明,在14.0-17.8℃孵化条件下,微耳石和矢耳石在受精后96h 30min出现,星耳石在出膜后第16天出现。仔稚鱼生长过程中矢耳石形状变化较大,由出膜时的圆形发育到稳定时的箭矢状。微耳石由近圆形发育成贻贝形,其中心核位置随发育明显偏移。星耳石形状不规则,从出现时的心形发育成为星芒状。微耳石和矢耳石在前后轴方向上后区的生长快于前区（P0.05）;在背腹轴方向上,微耳石腹区的生长快于背区（P0.05）,矢耳石背区的生长快于腹区（P0.05）,两对耳石的前后区半径之和与全长均呈线性相关。微耳石和矢耳石的第1个轮纹均在出膜后第2天形成,新增的轮纹数（微耳石IL,矢耳石IS）与出膜后的天数（D）表现出显著的线性相关,方程分别为: IL=0.9911D-1.0008（R2=0.9971,n=220,P0.001）和IS=0.9925D-0.10873（R2=0.9919,n=161,P0.001）,方程的斜率与1均无显著差异（P0.05）,表明两对耳石轮纹沉积均呈日周期性,生长轮为日轮。研究结果丰富了骨唇黄河鱼的发育生物学资料,可为研究其自然种群早期生活史提供参考。       

Age and growth of manybar goatfish Parupeneus multifasciatus (Mullidae) from the Nha Trang Bay of the South China Sea

The growth of individuals is analyzed in the mass tropical species manybar goatfish Parupeneus multifasciatus from the Nha Trang Bay of the South China Sea. The relationship between the body weight and body length is determined for the females and males. Among the fishes larger 180 mm fork length (FL), the males prevail. Linear growth of the sagitta is characterized by negative allometry in relation to body length, and sagitta growth in length is faster than in width. Age of fish assessed based on the analysis of daily increments on the sagitta does not exceed three years, and the majority of individuals reach the first sexual maturity by the age of one year. The growth rate of the fish is characterized by a large individual variation.     

Morpho-anatomy of the otic region in carapid fishes: eco-morphological study of their otoliths

Carapid species are characterized by so-called otophysical structures (sonic muscles, broad first apophyses covering the anterior part of the swimbladder, etc.) The family includes pelagic ( Pyramodon and Snyderidia ) and benthic ( Echiodon ) species and ones that are either commensal with ( Onuxodon, Carapus ) or parasites of ( Encheliophis ) invertebrates (sea cucumbers, etc). The aim of the present work was to seek possible relationships between the structures of the inner ear (particularly the sagitta) on the one hand and otophysical structures and lifestyles within the Carapidae family. In the eight species studied, the otic cavity is wide, the saccular otosac and its sagitta are particularly developed. The sacculi touch each other on the median line. A comparison of the inner ear structures reveals notably that the species with the most developed sagitta and sacculus are those with the largest parapophyses and have a commensal or parasitic lifestyle.     

Otolith development and daily increment formation in larvae of the Kabyabya,a Malawian cyprinid, <Emphasis Type="Italic">Opsaridium tweddleorum</Emphasis>

Features of the sagitta, asteriscus, and lapillus of laboratory-hatched larvae of the Kabyabya, Opsaridium tweddleorum, were investigated until day 33 after hatching. The sagitta was round until day 17, subsequently becoming arrowhead-shaped with the development of anterior and posterior rostra. Increments in the sagitta increased at the rate of one per day before rostrum formation. However, they were occasionally overestimated in rostrum sections as a result of subdaily increment occurrence. Furthermore, both anterior and posterior rostra were fragile, being thin and platelike, and were often damaged during the extraction and grinding processes. The lapillus was also round until day 17, thereafter becoming fan-shaped. Increments in the lapillus were distinctive from the core to the margin, usually increasing at the rate of one per day after hatching. The asteriscus appeared in fish larger than 9.15 mm in standard length (from day 17), being oval with a somewhat ambiguous core, causing difficulty in discerning the first increment. These features indicated that the lapillus was the most appropriate otolith part for daily increment analysis in this species, although the sagitta was useful before rostrum formation.     

Otolith morphology and periodicity of increment formation on the sagitta of manybar goatfish Parupeneus multifasciatus (Mullidae)

Otolith morphology and microstructure of the sagitta are described in the mass tropical species manybar goatfish Parupeneus multifasciatus. The hatch check is absent on the sagitta, and the appearance of the first contrasting increment is connected with the transition of the larva to exogenous feeding. The increments are distributed within several concentric zones, and each zone is separated by more pronounced dark areas (in transmitted light) of the increments (checks). The number of increments within a zone is variable; and the modal group (with the exception of the first zone from the primordium to the first check) includes from six to ten increments. In the juveniles, the periodicity of increment formation on the sagitta ranges from <1 to >3 in a day, but it is close to one increment per day in the individuals larger than 86 mm FL and 11 g in weight. The number of increments deposited in a day does not depend on the growth rate or feeding frequency of the juveniles.     

Daily growth increments in the larval otolith of the Japanese eel,Anguilla japonica

Early formation of otolith was studied on artificially hatched larvae of the Japanese eel,Anguilla japonica. Newly hatched larvae had a pair of sagittae which were flat and subelliptical with 8.3 μm in mean diameter. The diameter of the sagitta increased linearly with age. No growth increments were observed in the sagitta at hatching, while larvae which were 2, 4 and 6 days old had on average 2.1, 3.6 and 6.0 increments, respectively. The number of the increments (Y) and the age in days after hatching (X) showed a close linear relationship (Y=0.96X+ 0.06, r = 0.913, n = 40), suggesting daily deposition of sagittal increments. In 95 % of the field-caught elvers of this species, a distinct dark ring (check) with the diameter of 6–12 μm was found around the nucleus of the sagitta. This seems to be a “hatch check” deposited at hatching, since its diameter roughly agreed with that of the sagitta in the newly-hatched larvae. Possibly, the number of the increments outside the hatch check represents the age of the fish in days.     

青藏高原东缘同域分布的2种橐吾属杂草的合子前生殖隔离

生殖隔离是阻止种间杂交、保持物种完整性和独立性的关键,对生物多样性的产生和维持有重要意义.不同物种间的生殖隔离形成阶段、方式和强度不完全相同,因而对物种间隔离机制的研究有助于揭示物种形成和维持机制.对青藏高原东缘同域分布的2种橐吾属杂草黄帚橐吾和箭叶橐吾的花期物候观察、访花昆虫观察及花粉-柱头亲和性进行研究,分析了2种橐吾多种合子前生殖隔离机制的特点及其在生殖隔离中的作用.结果表明: 黄帚橐吾种群花期比箭叶橐吾早20 d左右,虽然盛花期存在差异,但是2种群花期存在10 d左右的重叠期,并且在重叠期内2种橐吾花粉和柱头均具有活性.2种橐吾共享传粉昆虫,为泛化传粉模式,并且传粉者对2种植物的访花行为相似,存在2种植物间交叉访问.尽管2种橐吾花期不存在完全的时间隔离,也不存在完全的传粉者隔离,但2种橐吾柱头对异源花粉的亲和性差,表现为柱头对异源花粉有明显的排斥反应,异源花粉管在柱头上的生长过程明显受阻.这种花粉-柱头排异形式很有可能是2种橐吾属植物重要的合子前隔离机制,从而避免了种间的自然杂交,更好地维持了自然种群的多样性和遗传结构的稳定性.     

阿拉善荒漠连续放牧对三趾跳鼠巢区的影响

三趾跳鼠(Dipus sagitta)是内蒙古西部荒漠草原和沙地的优势害鼠,巢区研究对了解探讨其繁殖策略和种群动态规律有着重要的理论和实践意义。本研究通过2012~2014年的野外标志重捕实验,对三趾跳鼠的巢区在连续放牧和禁牧条件下的变动特征进行了分析。结果表明,连续放牧区雌性三趾跳鼠在6月的巢区范围显著大于禁牧区(P0.05);禁牧区雄性三趾跳鼠的巢区仅在7月份显著大于连续放牧区(P0.05),其他季节没有显著差异(P0.05)。放牧对雄性巢区无显著影响(P0.05),但连续放牧使雌性三趾跳鼠巢区范围显著大于禁牧区。雌性与雄性三趾跳鼠巢区均与一年生草本生物量存在正相关关系。这些结果表明,相对于雄性三趾跳鼠来说,雌性对由放牧导致的食物资源变化比较敏感,这种现象在哺乳期更为显著;繁殖是影响雄性三趾跳鼠巢区的因素之一。因此,保卫资源假说的理论可能是放牧导致三趾跳鼠巢区变化的重要原因之一。     

Eco-morphological patterns of the sagitta of Antarctic fish

Morphology and morphometry of the sagittae otolith were studied in pelagic and mesopelagic fish. The shape, margins and rostrum of four groups of otoliths from several species were analyzed: group 1 (pelagic fish associated with the under ice cover N = 42), group 2 (pelagic fish associated with water offshore N = 9), group 3 (mesopelagic fish associated with extensive vertical migration N = 57) and group 4 (mesopelagic fish associated with short vertical migration N = 54). E (maximum width of the sagitta /maximum length of the sagitta %), R (rostrum length (RL)/maximum length of the sagitta %) and S (sulcus area (SS)/otolith area (OS) %) indexes were calculated for each species. Sagittae of pelagic groups (1 and 2) showed the smallest sagitta dimensions in relation to the total length of the fish, in this group the sagitta shape is variable. Sagittae of mesopelagic fish (groups 3 and 4) showed variable shape and edges. The shape in group 4 was polygonal and these species have more width than length. Statistical analysis showed significant differences in the E, R and S indexes. These results were compared with other 19 species, belonging to six families, taken from a publisher-edited literature. E, R and S-values could be used to characterize the sagittae of the Antarctic fish and could be considered as a useful tool for fish ecology studies.     

Otolith Morphology and Relationships of Several Fish Species of the Suborder Scorpaenoidei

Journal of Ichthyology - Otolith (sagitta) morphology is described in six tropical fish species belonged to different genera of the suborder Scorpaenoidei: Synanceia horrida, Inimicus sinensis,...     

Age and growth information available from the otoliths of the Hawaiian snapper,Pristipomoides filamentosus

The otoliths of tropical fish may provide important life history information incorporated within their structural and chemical constituents. All three otoliths (sagitta, lapillus, asteriscus) of the tropical fish Pristipomoides filamentosus were examined internally by Scanning Electron Microscope methods to observe micro-increments and externally to determine three dimensional structure. It was discovered that the sagitta contained four cores and that the plane chosen to be sectioned for micro-increment enumeration could result in errors if more than one core were transversed. The medial cross sectional plane was consequently resolved to effer the most accurate micro-increment counts. Obserations of lapilli also revealed micro-increments and subsequent counts were closely correlated to those detected in the sagittae. The visualization of increments made it feasible to assess age and evolve a growth model. In addition, sagitta weight was found to be related to growth rate and may provide a quick estimate of relative growth. Chemical analyses of otoliths for stable isotopes and Sr/Ca ratios all suggested that an individual fish inhabited warmer waters as it became older. A combination of otolith structural and chemical information can provide age and growth data which is essential to the calculation of accurate population parameters.     

Variation of Otolith Structure in Amur Sleeper Perccottus glenii (Odontobutidae) Populations from Central Russia

Journal of Ichthyology - Development of annual increments on the otoliths (sagittae) of Amur sleeper Perccottus glenii, as well as the sagitta shape and bilateral asymmetry, is analyzed in the...     

Otolith and somatic growth rates in Atlantic salmon parr, Salmo salar L: evidence against coupling

It is often assumed that otolith growth is in some way dependent on somatic growth (i.e. that the two processes are coupled). We examined the relationships between sagitta radius and fork length in 0+ Atlantic salmon parr that would subsequently smolt aged 1 + (UMG fish) or 2+ (LMG fish). Repeated measurements of fork lengths of individually marked parr, taken over a 211-day period from first feeding, were compared to sagitta radii on the same measuring dates (obtained by analysis of daily increments). The results showed that there was a linear relationship between fork length and otolith radius in UMG parr. However, this was not true for LMG parr. These fish enter a state of natural anorexia in their first autumn (despite excess food), but their otoliths continued to grow at the same rate despite the virtual cessation of somatic growth; they had therefore developed disproportionately large otoliths by the end of the study period. The relative growth rates of soma and otoliths first changed in LMG fish in late July/early August; this is the most precise estimate yet obtained of the timing of divergence in the developmental pathways of UMG and LMG parr. The rate of sagitta accretion was consistently lower in LMG parr, possibly indicating a lower metabolic rate in these fish. The results are discussed in relation to previous theories of the relationship between otolith and somatic growth.     

Otolith size trends in marine fish communities from different depth strata

A comparison of 681 saccular otoliths (sagitta) from 134 species belonging to six demersal communities from different depth strata and the epipelagic community from the north-western Mediterranean Sea was made in order to study otolith relative size and function related morphologies. A relationship between otolith size composition, habitat and depth was found. The epipelagic community was characterized by species with very small and small otolith sizes (68% of the epipelagic species). In the demersal communities, the proportion of species with large sagitta increased with depth until 750 m (reached 50% of the species of the upper slope). The abyssal community (between 1000 and 2000 m), however, was characterized by a decrease in the mean otolith size and an increase in the proportion of species with very small otoliths. With exception of the abyssal community, endogenous causes (a mixture of geneaology, plesiomorph characters shared by the all species of the taxonomic group and recent adaptive ones) may be even more important than exogenous factors in determining the otolith relative size. Within the endogenous causes that condition sagitta size, the adaptive features associated with specialization in acoustic communication are relevant.     

Fourth specimen of the deep benthopelagic ophidiid fish, Apagesoma delosommatus (Hureau, Staiger & Nielsen, 1979)

A fourth capture and third extant specimen of the ophidiid, Apagesoma delosommatus , is reported from tropical eastern North Atlantic continental rise waters. Its morphometric and meristic characters are compared with the holotype and paratype and its left sagitta is illustrated.     

Première découverte d’un squelette de Channidae (Poisson téléostéen) dans le Miocène inférieur d’Illerkirchberg, près d’Ulm (Wurtemberg, Allemagne)

A skeleton of a Channid fish is reported for the first time from the European Lower Miocene. Because of the lack of any appropriate diagnostic character, it is nevertheless impossible to determine if it belongs either to the Asiatic genusChanna Scopoli or to the African one,Parachanna Teugels &Daget. For this reason, its palaeobiogeographical significance remains unclear. Otoliths (sagitta) that very likely belong to the same Channid species have been described from Illerkirchberg asChanna elliptica (vonSalis). They are compared to the sagitta from recent species of the generaChanna (Scopoli) andParachanna (Teugels &Daget). Their morphological characters are intermediate between those characterizing the sagitta of both genera.     

Which geometric model for the curvature of 2-D shape contours?

We investigated the geometric representations underlying the perception of 2-D contour curvature. 88 arcs representing lower and upper halves of concentric circles, or halves of ellipses derived mathematically through planar projection by affinity with the circles, a special case of Newton's transform, were generated to produce curved line segments with negative and positive curvature and varying sagitta (sag) and/or aspect ratio. Aspect ratio is defined here as the ratio between the sagitta and the chord-length of a given arc. The geometric properties of the arcs suggest a regrouping into four structural models. The 88 stimuli were presented in random order to 16 observers eight of whom were experienced in the mathematical and visual analysis of 2-D curvature ('expert observers'), and eight of whom were not ('non-expert observers'). Observers had to give a number, on a psychophysical scale from 0 to 10, that was to reflect the magnitude of curvature they perceived in a given arc. The results show that the subjective magnitude of curvature increases exponentially with the aspect ratio and linearly with the sagitta of the arcs for both experts and nonexperts. Statistical analysis of the correlation coefficients of linear fits to individual data represented on a logarithmic scale reveals significantly higher correlation coefficients for aspect ratio than for sagitta. The difference is not significant when curves with the longest chords only (7 degrees -10 degrees ) are considered. The geometric model that produces the best psychometric functions is described by a combination of arcs of vertically and horizontally oriented ellipses, indicating that perceptual sensations of 2-D contour curvature are based on geometric representations that suggest properties of 3-D structures. A 'buckled bar model' is shown to optimally account for the perceptual data of all observers with the exception of one expert. His perceptual data can be linked to a more analytical, less 'naturalistic' representation originating from a specific perceptual experience, which is discussed. It is concluded that the structural properties of 'real' objects are likely to determine even the most basic geometric representations underlying the perception of curvature in 2-D images. A specific perceptual learning experience may engender changes in such representations.     

内蒙古半干旱区鼠类群落结构及鼠害危害类型的研究

自1988-1993年在内蒙古半干旱区约110000km² 的面积上设置样地251个,用夹日法对鼠类群落进行调查,用每个样地主要鼠种捕获率和样地构成分类量刚,应用SAS系统的快速聚类法进行分类;分类结果结合该地区地带性植被分布的特征和地貌、地形特征,将该地区的鼠类群落划分为9个地带性鼠类群落并研究其结构特征,同时根据地带性鼠类群落分布与结构特征及当地实际鼠害状况将内蒙古半干旱区鼠害划分为5大害区的7种危害类型：Ⅰ.荒漠草原鼠害危害区:①小毛足鼠、三趾跳鼠危害类型;②戈壁五趾跳鼠、赤颊黄鼠危害类型;Ⅱ.草原化荒漠鼠害鼠害危害区：③戈壁五趾跳鼠、三趾跳鼠危害类型;Ⅲ.沙地草场鼠害区：④小毛足鼠、三趾跳鼠、子午沙鼠危害类型;Ⅳ.阴山北麓旱作农田危害区：⑤长爪沙鼠、小毛足鼠危害类型;⑥长爪沙鼠、草原黄鼠危害类型;Ⅴ.阴山山脉中段次生林地和人工林地危害区：⑦棕背繙、大林姬鼠危害类型。