Length–weight relationship of Rhinobatos horkelii Müller & Henle, 1841 and Zapteryx brevirostris (Müller & Henle, 1841) off Brazil,southwestern Atlantic Ocean

This study reports the length–weight relationships (LWRs) for two elasmobranch species, Rhinobatos horkelii Müller & Henle, 1841 and Zapteryx brevirostris (Müller & Henle, 1841) collected from the southwestern Atlantic, off Brazil. Both are considered endangered species. The LWR data can be taken into consideration for further management and conservation plans.     

Feeding habits of ocellate spot skate,Okamejei kenojei (Müller & Henle, 1841), in coastal waters of Taean,Korea

The feeding habits of Okamejei kenojei were studied using 592 specimens collected in the coastal waters of Taean, Korea from April 2008 to March 2009. O. kenojei is a bottom‐feeding carnivore that consumes mainly shrimp, fishes, and crabs. Its diet also includes small quantities of amphipods, mysids, cephalopods, euphausiids, copepods, isopods, and polychaetes. The total length (TL) of individuals in this study ranged from 8.2 to 49.0 cm. Cluster analysis based on %IRI (index of relative importance) identified three size classes. Group A (< 20 cm TL) ate primarily caridean shrimp and amphipods; group B (20–30 cm TL) ate exclusively shrimp; and group C (> 30 cm TL) ate penaeoidean shrimp, fishes, and crabs. O. kenojei showed ontogenetic changes in feeding habits. Although shrimps were the primary food consumed by all size groups, the proportion of shrimp in the total diet decreased and the consumption of fishes and crabs gradually increased with the body size of O. kenojei. Size of the prey organisms also increased. Smaller individuals fed mainly on small prey, such as amphipods, mysids, and small shrimp, whereas larger individuals preferred larger prey, such as larger shrimp, fishes, and crabs. The size‐related diet breadth and the percentage of empty stomachs were significant; the diet breadth gradually increased with body size, whereas the percentage of empty stomachs decreased. Seasonal changes in the O. kenojei diet were not significant, but shrimp constituted 97.3% of the summer diet by %IRI. Seasonal changes in diet breadth and the percentage of empty stomachs were not significant.     

Reproductive biology of the Brazilian guitarfish,Pseudobatos horkelii (Müller & Henle, 1841) from southeastern Brazil,western South Atlantic

This study provides information on the seasonal occurrence, length‐width relationship, sexual development and size at first maturity of the critically endangered Brazilian guitarfish Pseudobatos horkelii in southeastern Brazil. Samples were obtained from September 2007 to August 2009 from commercial fisheries off São Paulo State coast at depths of 10–50 m, with net mesh sizes of 150 mm in the main net and 100 mm in the cod end. A total of 143 specimens (71 males, 72 females) were analyzed. Total length (TL), disc width (DW), sex and reproductive variables were recorded for each individual. Pseudobatos horkelii presents sexual dimorphism in length‐width relationships, with females attaining larger TL and DW. Females also mature at a larger TL, at 81.1% of the maximum TL, while males mature at 67.8% of the maximum TL. No specimens were captured in winter, and only a small sample size was observed in autumn. Males captured in spring and summer presented semen in the seminal vesicle, indicating that this species may reproduce in the warmer months, as already observed for other Rhinobatidae as well as for P. horkelii in southern Brazil.     

The ovarian cycle of the cuckoo ray, Raja naevus (Müller and Henle), in the Celtic Sea

One hundred female Raja naevus from the South Celtic Sea were examined every month for 14 consecutive months, for the characteristics of their ovarian cycle. Egg-laying occupied more than half of the cycle. All females followed the same genital cycle but independently of each other. On the average 56% of adult females were at egg-laying stage at any time throughout the year. Fecundity is estimated at 90 eggs a year.     

Reproductive biology and population variables of the Brazilian sharpnose shark Rhizoprionodon lalandii (Müller & Henle, 1839) captured in coastal waters of south-eastern Brazil

Throughout 1 year, from October 2003 to September 2004, 88 visits to the landing site of a small urban fishery (APREBAN) in Rio de Janeiro city were conducted and 816 specimens of Rhizoprionodon lalandii were analysed. The sample, mostly females, was composed of two cohorts: young-of-the-year were abundant in spring and summer and adults predominated in autumn and winter. Gravid females were most abundant from April to June, whereas post-partum females composed most of the catch in August to September. Adult males were present all year although were more abundant between February and July. No neonates were captured during the study and most embryos collected measured slightly below the reported total length ( L _T) at time of birth ( L ₀) for the species, suggesting that parturition may occur slightly outside the main fishing grounds or that neonates were not captured in commercial gillnets set at this time of the year. The mean L _T at maturity ( L _T50) for males was 578 mm and females matured between 620 and 660 mm, although a precise estimate of L _T50 for females could not be determined. The total length ( L _T) and total mass ( M _T) relationship     was calculated for both sexes and showed no significant differences. The mean condition factor increased steadily from February to July followed by a steep decrease in values relative to females in August and September, suggesting a pupping season. The present study area can be classified as a coastal juvenile habitat and a probable mating ground for R. lalandii .     

Aspects of the biology of Staphylinus olens (Müller), Britain's largest Staphylinid beetle

• 1 Methods for rearing Staphylinus olens (Müller) (Col., Staphylinidae) are described, and development compared with other species of Coleoptera.
• 2 The distribution of S.olens over an area of Manchester is noted, and biological comparisons made with a laboratory population from South Wales. In the area sampled, most individuals live on well-drained soils, possibly because successful pupation occurs under dry conditions.
• 3 ‘Courtship’ and mating are described.
• 4 Egg-laying, the egg, and its hatching are described, and compared with other coleopteran eggs.
• 5 Headwidths of laboratory larvae were recorded, and are compared with those of other beetle larvae.
• 6 Instars I and II lasted 44–45 days, although first instar larvae which eventually pupated had a mean duration of 33.5 days. Instar III averaged 102 days, but this time became shorter with later hatching, roughly synchronizing adult emergence.
• 7 Pupation and the obtect pupa are described. Pupal development took 32–37 days, after a 10–14 day prepupation period.
• 8 Newly emerged adults may construct winter burrows after autumn breeding. Second season adults may not hibernate, and often fail to survive another winter.
• 9 Food is manipulated by mandibles and legs, but no solids are consumed. Adults and larvae will eat many foodstuffs.

     

Size at hatching and incubation period of Sympterygia bonapartii (Müller & Henle, 1841) (Chondrichthyes, Rajidae) bred in captivity at the Temaiken Aquarium

Two mature Sympterygia bonapartii held in captivity laid a total of 136 egg cases, 33 of them were incubated at constant temperature (16·5° C), salinity (36) and photoperiod (12L:12D). The hatching rate was 100%. Juvenile fish hatched after 135 ± 10 days (mean ± s . d .) and the mean total length, disc width and mass at hatching were 140 mm, 86 mm and 15·1 g respectively.     

Reproductive patterns of Sardinella maderensis (Lowe, 1841) off Cameroon

The gonadosomatic index and gonad mean weight of Sardinella maderensis off the west coast of Cameroon were used to assess their reproductive patterns. Results showed that first maturity is at about 17 cm total length, and is the same for both males and females. S. maderensis breeds continuously but with two spawning peaks, a major one from April to July and a minor one from December to January.
Réumé
Reproduction des Sardinella maderensis sur la côte ouest du Cameroun
L'indice gonadosomatique et le poids moyen des gonades ont été utilisés pour évaluer les schimas de reproduction des Sardinella maderensis (Clupeidés) dans une étude menée sur la côte ouest du Cameroun. Dapres les risultats obtenus, la taille de premiére maturité est identique chez les msàles et chez les femelles (de l'ordre de 17 cm de longueur totale). S. maderensis se reproduit continuellement avec deux piriodes de grande ponte, I'une d'avril sà juillet et l'autre, moins importante, de décembre sà janvier.

Zusammenfassung

Reproduktionsmodus von Sardinella maderensis an der Westküste won Kamerun
Der gonado-somatische Index und das mittlere Gonadengewicht wurden zur Beurteilung des Repro-duktionsmodus von Sardinella maderensis an der Westküste von Kamerun herangezogen. Die Ergeb-nisse zeigen, daß die Länge der Erstlaicher sowohl für Weibchen als auch für Männchen bei etwa 17 cm Totallänge liegt. S. maderensis laicht kontinuierlich, mit zwei ausgeprägten Spitzen: eine Hauptlaichpe-riode zwischen April und Juli und eine schwächer ausgeprägte zwischen Dezember und Januar.     

The population biology of the acanthocephalan Pomphorhynchus laevis (Müller) in the River Avon

Regular samples of Gammarus pulex and dace Leuciscus leuciscus and occasional grayling Thymallus thymallus and chub L.cephalus were examined from the River Avon, Hampshire, for the presence of the acanthocephalan Pomphorhynchus leavis . The parasite only occurred in medium sized Gammarus due to lower probability of contact with small gammarids and stunted growth and selective mortality amongst older infected ones. No cycles in incidence or development of the parasite in G.pulex were observed. The parasite infected gammarids and grew in all months, and cystacanths were available throughout the year. Despite seasonal feeding activity and dietary preferences, fish fed on Gammarus and acquired infections in all months. Dispersion of P.laevis within the fish population was related to host feeding behaviour. No evidence of seasonal cycles in incidence or intensity of infection in fish was found, and observed monthly changes in the parasite population were related to changes in size structure of the host sample. In dace and grayling P.laevis grew little and matured only in summer, but in chub it grew and produced acanthors all year. The parasite population in fish appeared to be in a state of dynamic equilibrium and gain and loss of parasites took place throughout the year with the level of infection at any moment being determined primarily by the feeding behaviour of the host. This relationship between host diet, water temperature and parasite population size is discussed, and P.laevis in the R. Avon compared with other localities and other parasites.     

Reproductive biology of the southern thorny skate Amblyraja doellojuradoi (Chondrichthyes,Rajidae)

The total lengths (L_T) of 193 males (209–556 mm) and 130 females (275–515 mm) of Amblyraja doellojuradoi, a commercial by‐catch species on the Argentinean continental shelf, which are increasingly retained, were analysed. No sexual dimorphism was observed in the L_T at which 50% of individuals were sexually mature; males matured at 448 mm and females at 411 mm, c. 80 and 82% of maximum L_T. The hepato‐somatic index was similar among sexes, but significantly different between maturity stages, being lower in mature than immature specimens. Males had no seasonal difference in the hepato‐somatic index and females had the lowest index in autumn. The gonado‐somatic index was lower in males than in females and significantly higher in mature than immature specimens of both sexes. Males had the highest index in autumn and females had no seasonal difference. Collectively, these results would indicate that A. doellojuradoi breeds in autumn.     

Movement heterogeneity of dugongs, Dugong dugon (Müller), over large spatial scales

Seventy dugongs were fitted with satellite PTTs and/or GPS transmitters in sub-tropical and tropical waters of Queensland and the Northern Territory, Australia. Twenty-eight of the 70 dugongs were also fitted with time-depth recorders. The dugongs were tracked for periods ranging from 15 to 551 days and exhibited a large range of individualistic movement behaviours; 26 individuals were relatively sedentary (moving < 15 km) while 44 made large-scale movements (> 15 km) of up to 560 km from their capture sites. Male and female animals, including cows with calves, exhibited large-scale movements (LSM; > 15 km). Body length of travelling dugongs ranged from 1.9 to 3 m. At least some of the movements were return movements to the capture location, suggesting that such movements were ranging rather than dispersal movements. LSMs included macro-scale regional movements (> 100 km) and meso-scale inter-patch local movements (15 to < 100 km) and were qualitatively different from tidally-driven micro-scale commuting movements between and within seagrass beds (< 15 km). The mean ± S.E. macro-scale movement distance per individual was 243.8 ± 35.4 km (N = 14 individuals that travelled > 100 km), with a mean ± S.E. travel time of 179.8 ± 29.0 h. The mean ± S.E. meso-scale movement distance per individual was 49.7 ± 3.3 km (N = 28 individuals that made movements of 15-100 km), with a mean ± S.E. travel time of 52.3 ± 7.1 h. LSMs were rapid and apparently directed (mean ± S.E. travel speeds for GPS tagged animals; meso-scale movements = 1.3 ± 0.11 km/h, min = 0.3, max = 3.0; macro-scale movements = 1.6 ± 0.16 km/h, min = 0.8, max = 1.3). Tracked dugongs rarely travelled far from the coast (mean ± S.E. max distance = 12.8 ± 1.3 km). Dive profiles from the time-depth recorders suggest that dugongs make repeated deep dives while travelling rather than remaining at the surface, increasing their likelihood of capture in bottom set gill nets. Some animals caught in the high latitude limits of the dugongs' range on the Australian east coast in winter apparently undertook long distance movements in response to low water temperatures, similar to migrational movements by Florida manatees. Our findings that dugongs frequently undertake macro-scale movements have implications for management at a range of scales, and strengthen the aerial survey and genetic evidence for management and monitoring at ecological scales that cross jurisdictions.     

Reproductive biology of the blue jack mackerel,Trachurus picturatus (Bowdich, 1825), off the Canary Islands

The reproductive cycle of the blue jack mackerel, Trachurus picturatus, had not been described for the Canary Islands. Between March 2005 and March 2006 monthly samples of T. picturatus were collected randomly at the central fishery wharf from the commercial catches of purse‐seiners in Tenerife Island waters (Canary Islands). Some 2472 specimens were analysed, with total lengths from 10.4 to 31.9 cm. Although females outnumbered males in summer, males were more abundant in the sex ratio (1.36 : 1). Based on the monthly evolution of the gonado‐somatic index and the proportion of mature individuals, the spawning season occurred between January and April, peaking in February. Lengths at first maturity (LFM) were calculated from the maturity ogives by the Gompertz model for all specimens (22.79 cm), for males (21.20 cm) and for females (23.05 cm). In this area the minimum legal size for T. picturatus is actually smaller than the length at first maturity and should be revised to avoid depletion of the stock.     

The food of Planaria torva (Müller) (Turbellaria-Tricladida), a laboratory and field study

The food of Planaria torva was examined in the laboratory by exposing a range of potential prey to the triclad and observing prey mortality. Under these conditions P. torva fed mainly upon tubificid oligochaetes and gastropods. The former activity was regarded as untypical of the field situation and due to limitations of the laboratory habitat. The food of P. torva was determined in the field by taking monthly samples from October 1967 to May 1969 of a population living in Linlithgow Loch, West Lothian, Scotland. A serological technique was used to examine the gut contents of the field triclads. For reasons explained in the text, the prey organisms tested for serologically were gastropods, oligochaetes (Tubificidae), Asellus and chironomid larvae. Planaria torva fed most extensively on Gastropoda, Asellus was the second main food while Tubificidae and Chironomidae were taken only seasonally and in small numbers. The limited extent of feeding on tubificids supports the laboratory data. Small P. torva gave proportionately fewer positive reactions to the prey antisera than large individuals. This was explained by the fact that small individuals occurred most frequently in the warmer months and took smaller meals; both of these features shorten the detection period of food in the gut and therefore give fewer reactions. The diet of small and large P. torva was similar in the field and showed considerable overlap with that of Dugesia polychroa. The food of Polycelis tenuis, Dendrocoelum lacteum and Dugesia polychroa in Linlithgow Loch was described on an annual basis and the results confirmed earlier observations.     

Thamnocephalus cerebrinoxius n. g., n. sp. (Copepoda: Sphyriidae), a parasite in the nasal capsules of Leptocharias smithii (Müller & Henle, 1839) (Pisces: Leptochariidae) off the coast of Senegal

Thamnocephalus cerebrinoxius n. g., n. sp. is a sphyriid copepod found in the nasal capsules of a small enzootic west African shark, Leptocharias smithii (Leptochariidae), caught off the coast of Senegal. The most characteristic feature of this copepod is its holdfast of numerous, profusely branching dendrites that penetrate the olfactory lobe of the host's brain. This type of host-parasite relationship is unique among all known parasitic copepods.     

Lepidasthenia loboi sp. n. from Puerto Madryn,Argentina (Polychaeta,Polynoidae)

Among polychaetes, polynoids have the highest number of symbiotic species found living with a wide variety of marine invertebrates, including other polychaetes. Lepidasthenia Malmgren, 1867 and Lepidametria Webster, 1879 were regarded as synonyms but belong to different subfamilies, although both have species associated with thelepodid or terebellid polychaetes. In this contribution Lepidasthenia loboi sp. n. is described from several specimens associated with the thelepodid Thelepus antarcticus Kinberg, 1867, collected on a rocky shore near Puerto Madryn, Argentina. Lepidasthenia loboi sp. n. can be confused with Lepidasthenia esbelta Amaral & Nonato, 1982 because both live with Thelepus, are of similar sizes with similar pigmentation patterns, and have giant neurochaetae. However, in Lepidasthenia loboi sp. n. all eyes are of the same size, cephalic and parapodial cirri are tapered and mucronate, the second pair of elytra is larger than the third, the ventral cirri arise at the base of parapodia such that they do not reach chaetal lobe tips, and neuraciculae are tapered. On the contrary, in Lepidasthenia esbelta the posterior eyes are larger than anterior ones, cephalic and parapodial appendages are swollen subdistally, the second and third pairs of elytra are of the same size, the ventral cirri arise medially such that their tips reach the neurochaetal lobe tips, and the neuraciculae have falcate tips. Some comments about other genera in the Lepidastheniinae, a simplified key to its genera, and a key to Lepidasthenia species with giant neurochaetae are also included.     

Reproductive biology of the sand dollar,Peronella lesueuri (L. Agassiz, 1841) (Echinoidea: Clypeasteroida: Laganidae), in south-western Australia

The reproductive biology of the sand dollar Peronella lesueuri was studied between 2009 and 2011 in Cockburn Sound, a large coastal embayment in south-western Australia. Individuals of P. lesueuri did not display sexual size-dimorphism, and the population was found to have a sex ratio of 1:1. Maturity occurred over the range of 80–115 mm with all sand dollars larger than 115 mm having distinct gonads. Monthly histological analysis of gonads and changes in oocyte proportions over time indicated that P. lesueuri has an annual reproductive cycle; gametogenesis occurs in spring and spawning in summer. Differences in the rate of gametogenesis between 2009/2010 and 2010/2011 may have been influenced by higher temperatures experienced in 2010/2011. P. lesueuri have large ova (mean?=?210 μm), which suggests the species has lecithotrophic larval development.     

The reproductive biology of Scleropages formosus (Müller & Schlegel) (Osteoglossomorpha, Osteoglossidae) in Malaya, and the morphology of its pituitary gland

This is a study of the reproductive biology and morphology of the pituitary gland of the osteoglossid fish Scleropages formosus (Müller & Schlegel). The fish spawn in the Tasek Bera waterways of Pahang, Malaysia during the rainy season beginning in August. Young fish are incubated in the mouth of the male parent until free-swimming. Males mature in their 2+ year, when 30–45 cm in length. In mature specimens the testis is small, and little sperm is produced. Some females mature in their 2+ year, although at that time, most have only reached the stage of secondary oocyte production. The chorion and follicular granulosa of secondary oocytes are deeply invaginated into the cytoplasm. All fish spawn in their 3+ year, when 45–60 cm in length. The single ripe ovary contains 20–30 ova, each 1.9 cm in diameter. No fish of 4+ years were caught, which may be the result of mortality or emigration, or due to extraneous causes such as selectivity in the fishing techniques used.
The pituitary gland accords with the generalized teleost pattern and embryonic development. There is no saccus vasculosus. Adrenocorticotropic cells predominate in the proadenohypophysis, and somatotropic and luteotropic cells occur here. The mesoadenohypophysis contains gonadotropic and somatotropic cells; the former grow large in ripe specimens, so that the mesoadenohypophysis becomes much enlarged. The metaadenohypophysis contains relatively few cells, much neurohypophyseal ramification, and is deeply penetrated by the third ventricle of the brain.