Evolutionary history of frogfishes (Teleostei: Lophiiformes: Antennariidae): a molecular approach

Fishes of the family Antennariidae (order Lophiiformes) are primarily shallow-water benthic forms found in nearly all tropical and subtropical oceans and seas of the world, with some taxa extending into temperate waters. Despite an earlier attempt based on morphology, no previous hypothesis of intergeneric relationships of the Antennariidae exists. To resolve phylogenetic relationships within the Antennariidae, and to test the validity of species groups within Antennarius, DNA sequences from the mitochondrial 16S and cytochrome oxidase c subunit 1 (COI) genes, and nuclear recombination activating gene 2 (RAG2), for 25 described and four undescribed antennariid species, representing 10 of 12 known genera and one undescribed genus, were unambiguously aligned and analyzed using Bayesian and maximum likelihood methods. The markers were partitioned and analyzed for substitution saturation and only the third codon position of COI (COI-3) was found to have reached saturation. However, analysis of both datasets, one with the saturated data and one without, differed only slightly. All molecular analyses recovered two major clades, one comprised of Fowlerichthys, Antennarius, Histrio, and Antennatus; and another containing Rhycherus, Antennariidae gen. et sp. nov., Kuiterichthys, Phyllophryne, Echinophryne, Tathicarpus, Lophiocharon, and Histiophryne. Evidence is presented to illustrate a correlation between phylogeny, geographic distribution, and reproductive life history. The results of these analyses provide the first hypothesis of evolutionary relationships within the Antennariidae.     

Postsettlement growth of two estuarine crab species, Chasmagnathus granulata and Cyrtograpsus angulatus (Crustacea, Decapoda, Grapsidae): laboratory and field investigations

The estuarine grapsid crabs Chasmagnathus granulata and Cyrtograpsus angulatus belong to the most typical and dominant inhabitants of brackish coastal lagoons in southeastern South America. In a combined laboratory and field investigation of juvenile growth, we measured the increase in body size in these species under controlled conditions as well as in field experiments (in Mar Chiquita lagoon, Argentina), seasonal changes in size frequency distribution of a natural population, and growth related changes in selected morphometric traits of male and female juveniles (relations between carapace width, carapace length, propodus height and length of the cheliped, and pleon width). At 24°C, Cy. angulatus grew faster than Ch. granulata; it reached the crab-9 instar (C9; 13 mm carapace width) after 92 days, while Ch. granulata required 107 days to reach the C8 instar (7.4 mm). At 12°C, growth ceased in both species. The pleon begins to show sexual differences in the C5 (Cy. angulatus) and C8 instar (Ch. granulata), respectively, while the chelae differentiate earlier in Ch. granulata than in Cy. angulatus (in C4 vs C6). In the field, growth was maximal in summer, and was generally faster than in laboratory cultures. However, there is great individual variability in size (about 25% even in the first crab instar) and in size increments at ecdysis, increasing throughout juvenile growth. Our data indicate that, in the field, small-scale and short-term variations in feeding conditions, temperature, and salinity account for an extremely high degree of variability in the absolute and relative rates of growth as well as in the time to sexual differentiation. Received in revised form: 20 September 2001 Electronic Publication     

Histology of the fusion area between the parasitic male and the female in the deep-sea anglerfish Neoceratias spinifer Pappenheim, 1914 (Teleostei, Ceratioidei)

The article deals primarily with the histology of the fusion area between the head of the male and the skin of the female in two female Neoceratias spinifer, each of which had a single parasitic male attached. In this area, comprising the whole flattened upper part of the male head, the dermis of the male is completely fused with that of the female, leaving no remnants of the epidermis of either. In all other known cases permanent attachment of the parasitic male is accomplished by fusion of separate outgrowths from the male snout and lower jaw and the female skin. In the fusion area of N. spinifer two interconnected blood vascular plexus are present, the one located in the connective tissue of the male head, the other in that of the female skin. It is not known, however, whether the plexus in the female skin is provided with blood from the female blood vascular system, i.e. there is no critical proof of a real continuity between the female blood vascular system and that of the male. The eyes of both parasitic males are very degenerate. There is no histological evidence of degenerative changes in the male digestive system, heart or gills.     

Infanticide among free-ranging langurs (Presbytis entellus) at jodhpur (Rajasthan/India): Recent observations and a reconsideration of hypotheses

Considerable disagreement characterizes the debate concerning frequency, causation, and function of infanticide in connection with adult male replacements in bisexual one-male troops of hanuman langurs (Presbytis entellus). Detailed observations are presented about two noninfanticidal and three infanticidal male changes including six eye-witness and five presumed cases of infanticide within three langur troops during a long-term study at Jodhpur, Rajasthan, India. The results do not support any explanatory hypotheses focussing on social crowding, regulation of population density, social stress, sexual frustration, incest avoidance, or social bonding, but are in general though not total agreement with the reproductive advantage hypothesis: mainly unrelated infants were killed (one possible exception), the infanticidal male generally sired the subsequent offspring (one exception), and the mean interbirth interval subsequent to infanticide is by 2.1 months shortened. Likewise, several cases of stress induced abortions occurred. It is demonstrated that postconception estrous behaviour is by no means a female counterstrategy to infanticide in order to confuse males concerning the issue of paternity, since an infanticidal male did not spare the subsequent offspring of mothers who copulated with him during pregnancy and pregnant females did not discriminate between fathers and non-fathers.     

Sexual dimorphism, female reproduction and egg incubation in the oriental leaf-toed gecko (Hemidactylus bowringii) from southern China

We studied sexual dimorphism, female reproduction and egg incubation of the oriental leaf-toed gecko (Hemidactylus bowringii) from a population in southern China. The largest male and female in our sample were 60 and 57 mm snout-vent length (SVL), respectively. Males are the larger sex; sexual dimorphism in head size and tail length (TL) is evident in juveniles and adults, with males having larger heads as well as longer tails than females. Oviposition occurred between late May and late July. Females switched from laying two eggs early in the breeding season to 1-2 eggs later in the season. Clutch mass and egg mass were both independent of female SVL, whereas relative clutch mass was negatively correlated with female SVL. The previous conclusion that female H. bowringii lay a single clutch of eggs per breeding season is unlikely to be true. Thermal environments experienced by H. bowringii eggs affect incubation length as well as morphological and locomotor phenotypes of hatchlings. Hatchlings from eggs incubated at 30 degrees C were larger (SVL, tail length and body mass) and performed better in the racetrack than their counterparts from eggs incubated at 24 degrees C. Temperatures suitable for embryonic development are relatively high in H. bowringii, primarily as a consequence of the adaptive response to warm environments in southern China.     

The influence of mating system on seminal vesicle variability among gobies (Teleostei, Gobiidae)

A variety of sexual selection mechanisms have been implicated to drive the variability of the male reproductive tract in internal fertilizers, while studies on external fertilizers have been largely limited to exploring the influence of sperm competition on testis size and sperm number. Males in the Gobiidae, a speciose teleost family of demersal spawners with external fertilization, are known to be characterized by accessory structures to the sperm duct called seminal vesicles. These seminal vesicles secrete a mucus-enriched seminal fluid. Seminal vesicle size and function have been demonstrated to be influenced by sperm competition at the intraspecific level. With the aim to test the factors influencing the development of these male organs at the interspecific level, an independent contrast analysis was performed on 12 species, differing in mating system type, sperm competition risk, and duration of egg deposition. The type of mating system appears to be the main factor significantly affecting development of seminal vesicles, with males of monogamous species completely lacking or having extremely reduced organs.     

Characterization of blood cells and hematological parameters in Cichlasoma dimerus (Teleostei, Perciformes)

The aim of the present study was to obtain a basic knowledge of the hematology of Cichlasoma dimerus. The morphological features of blood cells were described according to the observations made by light and electron microscopy. Erythrocytes, thrombocytes and four types of leucocytes: lymphocytes, monocytes, heterophils and eosinophils, were distinguished and characterized. Thrombocytes are the most abundant blood cells after erythrocytes and are recognized easily from lymphocytes by morphological features and size. Heterophils and eosinophils are PAS positive. Hematological indices (RBC, WBC, PCV, Hb, MCV, MCH, MCHC and leucocyte differential count) were measured in one blood sample from 30 adult fish captured in Esteros del Riachuelo, Corrientes, Argentina (27 degrees 25'S, 58 degrees 15'W). The reference interval and the mean were determined for each hematological parameter evaluated. Contrary to other species, the percent of heterophils was found to be high in relation to the percent of lymphocytes. Low lymphocyte counts occurred in C. dimerus, as compared to these found in other fishes. Compared to most teleosts, this species has similar mean values for PCV and Hb and slightly higher for RBC. Statistical analysis revealed that differences in hematological parameters between male and female fish were not significant.     

Sexual differences in auditory sensitivity: mismatch of hearing threshold and call frequency in a tettigoniid (orthoptera,tettigoniidae: Zaprochilinae)

Summary Sexual dimorphism of the ear of an undescribed species of zaprochiline tettigoniid is described. The internal trachea, dedicated to hearing in other tettigoniids, is unmodified in the male but fully developed in the female. The external auditory spiracle is also lost in the male. In contrast, there is no difference between the sexes in the number of sensilla within the hearing organ. The male is 10 dB less sensitive than the female. The characteristic frequency of the hearing organ at 35 kHz does not match the carrier frequency of the male's call at 51 kHz. As a result of this mismatch the female is remarkably insensitive to the male's call (threshold at 75 dB SPL), and the male is even less sensitive (thresholds80 dB SPL). In nature this provides a maximum hearing range of the male of less than 50 cm.     

Functional anatomy of the luring apparatus of the deep-sea ceratioid anglerfish <Emphasis Type="Italic">Cryptopsaras couesii</Emphasis> (Lophiiformes: Ceratiidae)

The osteology and myology of the illicial apparatus of Cryptopsaras couesii were examined in an effort to elucidate function. The apparatus consists of two bones, a tiny illicial bone, completely enveloped by tissue of the esca, and an extremely long supporting pterygiophore that lies within a deep groove on the dorsal surface of the head. The anterior end of the pterygiophore emerges on the tip of the snout from between the frontal bones, while the posterior end, encased in a dermal sheath when the illicial apparatus is retracted, emerges on the back just anterior to the dorsal caruncles. Five pairs of muscles control movement of the illicial apparatus: small, short erectors and depressors control movement of the illicial bone, while extremely long inclinators, protractors, and retractors control movement of the pterygiophore. The protractors and retractors of C. couesii are more robust and much longer than those of other lophiiforms, indicating that the pterygiophore of this species has an exceptionally wide range of movement in the anterior and posterior plane. Moreover, these muscles wind around the pterygiophore in opposite directions, a unique anatomy that suggests that C. couesii extends and retracts the pterygiophore by rotation.     

Ultrastructural study of embryonic and early adult germ cells,and their support cells,in both sexes of Xiphophorus (Teleostei:Poeciliidae)

The ultrastructure of the early spermatogonia in mature testes of the platyfish, Xiphophorus maculatus, was compared to that of oogonia in mature ovaries of X. maculatus and the related X. nigrensis. Both cell types were very similar and, characterized as being large, oval to round cells containing large, central nuclei with prominent nucleoli. Abundant mitochondria with sparse transverse cristae were located at one pole or around the nucleus. Annulate lamellae and electron-dense granular material (nuage) were present. Other organelles were not prominent. A female that had received a testis graft had testicular tissue containing mature spermatozoa within the ovary, indicating that cells were present that could develop along the male line. Special crosses were carried out to obtain all-male embryos of X. maculatus and all-female embryos of X. nigrensis. The ultrastructure of the germ cells in all embryonic gonads was similar to that of the adult cells. These results suggest the presence of sexually undifferentiated germ cells in the adult gonads of both sexes. The support cells investing all of these germ cells were also similar structurally and appeared to be undifferentiated.     

Growth and reproduction in Canthigaster valentini (Pisces,Tetraodontidae): a comparison of a toxic reef fish with other reef fishes

Synopsis The growth and reproduction of Cantigaster valentini were studied in two sites at Lizard Island, Australia. C. valentini was found to be a gonochore, with a sex ratio very close to 1:1; sexes could be distinguished externally. The growth (in length) of known individuals from both sites was measured at least every two months over two years. Growth rates of males and females decrease as their sizes increase. Growth rates differ between sexes and between sites: males generally grow faster than females and individuals at Mermaid Cove generally grow faster than individuals at Palfrey Island. Spawning is demersal, it occurs daily between 0800 and 1600h, and continues year-round. For females the interval between successive spawnings varies from about 4 days in the warm-water season to about 10 days in the cool-water season. From a comparison of local reproductive output and local recruitment survivorship of larvae in the plankton was estimated to be much higher than in another species (Pomacentrus wardi) for which a similar estimate was available. We suggest that some aspects of the reproductive strategy of C. valentini differ from other, non-toxic reef fishes in ways consistent with a reduced threat of predation upon adults, eggs, and larvae: courtship and spawning are unhurried and occur throughout most of the day; spawning is unrelated to lunar cycles; there is no parental care or defense of fertilized eggs; and embryos often hatch on rising tides.Centre for Environmental and Urban StudiesSenior author's present address: School of Biological Sciences F07, University of Sydney, Sydney 2006, N.S.W., Australia     

Monogamy,spawning and skin-shedding of the sea moth,Eurypegasus draconis (Pisces: Pegasidae)

Synopsis The Red Sea seamoth, Eurypegasus draconis, has a social structure that involves close pair-bonding with a monogamous mating system. The occurrence of 61 specimens, 95.1% paired, were recorded in the Gulf of Aqaba, during summers 1989 and 1990. Fourteen pairs were tagged and seven of them were seen again at least once. Cumulative location maps for tagged individuals showed that they were not territorial or site-attached, home ranges of pairs overlapped, they had low mobility, and occurred in low densities. Dissections and histological analyses showed that pairs (n = 12) were heterosexual and all individuals were sexually mature. E. draconis is sexually dimorphic. Females (n = 13) have significantly larger carapace volumes than males (n = 13). In aquaria, pairs spawned repetitively at dusk. At the peak of a spawning rise they released pelagic eggs from which embryos hatched in 24–29h at 27.2°C. Unpaired individuals probably have little opportunity to meet and mate. Close pair-bonding that ensures the availability of a mate, probably evolved as a style for increasing reproductive success in these small fish that occur in low density. E. draconis sheds its skin in one piece every 1 to 5 days.     

Density-dependent parasitism of cowpea aphid,Aphis craccivora by Lysiphlebus fabarum,Binodoxys acalephae,and Aphidius matricariae (Hymenoptera: Braconidae: Aphidiinae)

Biological control, as a major component of pest management strategies, uses natural biological agents to reduce pest populations. Studying the interaction among Aphis craccivora and its parasitoids including, Lysiphlebus fabarum, Binodoxys acalephae, and Aphidius matricariae in 2016 and 2017 in Tehran Parke-Shahr, showed positive, significant correlations in all cases between the densities of three parasitoid species and that of aphid nymphs and adults. The density of the parasitoids increased by increasing the density of the aphids. The parasitoids showed aggregative behavior in response to different densities of the host. There was a positive density-dependent correlation between the density of A. craccivora and rate of parasitism. Parasitism rates of nymphs and adult aphids by L. fabarum, B. acalephae, and A. matricariae increased or decreased along with decline or increase in the population of the aphid host. In 2016 spring, the highest rates of parasitism on aphid nymphs by L. fabarum, B. acalephae, and A. matricariae were 46.82, 23.09, and 17.16%, respectively. In 2017 spring, the highest rates of parasitism on aphid nymphs by L. fabarum, B. acalephae, and A. matricariae were 48.97, 21.77, and 15.06%, respectively. So, given the accordance between changes in aphid population and that of parasitoids, and parasitoids’ efficacy in Tehran’s polluted air, they can be used as biological agents in the management of A. craccivora population.     

Growth, size and age at maturity of the agile frog (Rana dalmatina) in an Iberian Peninsula population

The mean age of a population of agile frogs (Rana dalmatina) from the Iberian Peninsula was estimated using mark and recapture and skeletochronology. Life-history parameters, including growth rate, body length, age and size at maturity, sexual dimorphism and longevity, were studied. The regression between age and snout-vent length (SVL) was highly significant in both sexes. Males reached sexual maturity at two years of age, although sometimes they can reach it at only one year of age. The average SVL at maturity was 51.75 mm (standard error (SE) = 0.71; n = 45). Females reached sexual maturity at two years of age with an average SVL of 62.14 mm (SE = 2.20; n = 14). A subset of the female population reached sexual maturity at three years of age. Growth was rapid until sexual maturity was reached. There was an overlap of SVL between different age classes. Growth was continuous, fulfilling the conditions of Von Bertalanffy's model. The growth coefficient (K) was 0.840 in males and 0.625 in females. The maximum SVL was greater in females (73.00 mm) than in males (59.50 mm). Sexual dimorphism was significantly biased towards females in all age classes. The maximum longevity observed was 6 years in females and 8 years in males. Management strategies for agile frogs should take into account factors such as these life-history characteristics.     

The ultrastructural and biosynthetic characteristics of steroidogenic cells in the gonad of Monopterus albus (Teleostei) during natural sex reversal

Summary The ultrastructural and biosynthetic characteristics of the steroid cells in the gonad of Monopterus albus have been studied. Ultrastructural features related to steroidogenesis have been identified in the interstitial Leydig cells, Sertoli cells, granulosa cells and thecal cells, and are especially abundant in the Leydig cells during the mid-intersexual phase. Steroidogenic ultrastructures in the Sertoli cells develop only during the maturation of the spermatogenic cysts, whereas in the granulosa and thecal cells, these features become obvious only during the maturation of the large oocytes. EM evidence also suggests a nutritive function for the Sertoli cells and the granulosa cells. Results of in vitro steroidogenic studies, using either testosterone or progesterone as a precursor, show a predominant conversion to androstenedione and 5-reduced compounds, and suggest a change in biosynthesis from 5-reduced products to androstenedione during sex reversal. 11-Ketotestosterone (11KT) has been identified, but not 11 -hydroxytestosterone. Production of 11 KT is high in the late intersexual and the male phases, but a lack of a marked variation in 11KT production between the early and the mid-intersexual phase suggests that this steroid is not a trigger for natural sex reversal in Monopterus.