Ecological determinants of parasite acquisition by exotic fish species

Disease‐mediated threats posed by exotic species to native counterparts are not limited to introduced parasites alone, since exotic hosts frequently acquire native parasites with possible consequences for infection patterns in native hosts. Several biological and geographical factors are thought to explain both the richness of parasites in native hosts, and the invasion success of free‐living exotic species. However, the determinants of native parasite acquisition by exotic hosts remain unknown. Here, we investigated native parasite communities of exotic freshwater fish to determine which traits influence acquisition of native parasites by exotic hosts. Model selection suggested that five factors (total body length, time since introduction, phylogenetic relatedness to the native fish fauna, trophic level and native fish species richness) may be linked to native parasite acquisition by exotic fish, but 95% confidence intervals of coefficient estimates indicated these explained little of the variance in parasite richness. Based on R²‐values, weak positive relationships may exist only between the number of parasites acquired and either host size or time since introduction. Whilst our results suggest that factors influencing parasite richness in native host communities may be less important for exotic species, it seems that analyses of general ecological factors currently fail to adequately incorporate the physiological and immunological complexity of whether a given animal species will become a host for a new parasite.     

Native fish avoid parasite spillback from multiple exotic hosts: consequences of host density and parasite competency

Disease-mediated impacts of exotic species on their native counterparts are often ignored when parasite-free individuals are translocated. However, native parasites are frequently acquired by exotic species, thus providing a mechanism through which native host-parasite dynamics may be altered. In Argentina, multiple exotic salmonids are host to the native fish acanthocephalan parasite Acanthocephalus tumescens. Field evidence suggests that rainbow trout, Oncorhynchus mykiss, may be a major contributor to the native parasite’s population. We used a combination of experimental infections (cystacanth—juvenile worm transmission from amphipod to fish; post-cyclic—adult worm transmission between definitive fish hosts) and dynamic population modelling to determine the extent to which exotic salmonid hosts may alter A. tumescens infections in native freshwater fish. Experimental cystacanth infections demonstrated that although A. tumescens establishes equally well in native and exotic hosts, parasite growth and maturity is superior in exotic O. mykiss. Experimental post-cyclic infections also showed greater establishment success of A. tumescens in O. mykiss, though post-cyclic transmission did not result in greater parasite size or maturity. Dynamic population modelling, however, suggested that exotic salmonids may have a very limited influence on the A. tumescens population overall, due to the majority of A. tumescens individuals being maintained by more abundant native hosts. This research highlights the importance of considering both a host’s relative density and its competency for parasites when evaluating whether exotic species can modify native host-parasite dynamics.     

Fish introduction and parasites in marine ecosystems: a need for information

Invasive species provide unique and useful systems by which to examine various ecological and evolutionary issues, both in terms of the effects on native environments and the subsequent evolutionary impacts. While biological invasions are an increasing agent of change in aquatic systems, alien species also act as vectors for new parasites and diseases. To date, colonizations by hosts and parasites have not been treated and reviewed together, although both are usually interwoven in various ways and may have unpredictable negative consequences. Fish are widely introduced worldwide and are convenient organisms to study parasites and diseases. We report a global overview of fish invasions with associated parasitological data. Data available on marine and freshwater are in sharp contrast. While parasites and diseases of inland freshwater fish, ornamental, reared and anadromous fish species are well documented, leading to the emergence of several evolutionary hypotheses in freshwater ecosystems during the last decade, the transfer of such organisms are virtually unexplored in marine ecosystems. The paucity of information available on the parasites of introduced marine fish reflects the paucity of information currently available on parasites of non-indigenous species in marine ecosystems. However, such information is crucial as it can allow estimations of the extent to which freshwater epidemiology/evolution can be directly transferred to marine systems, providing guidelines for adapting freshwater control to the marine environment.     

The life cycle of Haplorchis pumilio (Trematoda: Heterophyidae) from the Indian region

The life cycle of the heterophyid fluke, Haplorchis pumilio is elucidated for the first time from the Indian region. Various stages in the life cycle were established based on observations made on natural infections found in snails and fish in a freshwater stream at Visakhapatnam, India and experimental infections carried out in the laboratory. The thiarid snail, Thiara tuberculata served as the first intermediate host and a wide range of freshwater fish as second intermediate hosts. Natural infections with adult flukes were found in the piscivorous birds Ardeola grayii and Bubulcus ibis. Adults were raised experimentally in day-old chicks. Distinguishing features of the cercaria of H. pumilio are: a large body size (200-224 x 92-96 micro m), body-tail ratio of 1:2.1 and densely distributed pigment granules in the parenchyma imparting a brownish tinge to the body. Natural infections with metacercariae were found in the freshwater fish Channa punctatus, C. orientalis, Puntius sophore, Gambusia affinis and fingerlings of Cyprinus carpio and Liza macrolepis. Additionally, experimental infections were established in Therapon jarbua, Esomus danricus and Oreochromis mossambica. Metacercariae were embedded in the caudal muscles of fish and heavy infections induced mortality. Metacercariae were infective at about 15 days of age.     

Histopathology of fish parasite infections – importance for populations

There is a bewildering array of fish parasites and probably all fish species harbour one or more species. Under normal conditions hosts often show little or no signs of infection, either clinically or at the organ and tissue level. All tissues can be infected, including the blood. Coelozoic species generally do not elicit significant host responses. Any developmental stages, however, where these migrate through the host tissues may produce a cellular response if resident for sufficient time. Histozoic parasites are generally more likely to evoke a pathological response since they are invariably in more intimate contact with immunocompetent host cells such as lymphocytes and phagocytes. In some cases, particularly with protistan infections, host response can be dramatic and cause significant disease due to organ dysfunction, with subsequent mortalities. Infections of the external epithelia caused by a variety of parasites including Monogenea and Copepoda are also significant, especially when large numbers are present. Resulting tissue necrosis compromises osmoregulation and facilitates entry of prokaryote infections. Parasites have numerous strategies to evade detection within the host, but even ‘protected’ intracellular forms, e.g. microsporeans and muscle‐invading myxozoans are recognized when they outgrow their accommodation or large cysts rupture, presenting parasite antigens to the host. In most instances, an evolutionary balance has been achieved between the host and the parasite and even when histopathology is evident, this is frequently localized and does not unduly impair performance of the affected organ. Examples include chronic inflammation, granuloma formation and focal fibrosis. This paper outlines the principle histopathological responses to a variety of parasite groups and provides a more detailed treatment of selected parasitic infections in marine and freshwater fish species to illustrate the relative importance of acute and chronic parasitic infections for host survival.     

Host-pathogen-environment interactions predict survival outcomes of adult sockeye salmon (Oncorhynchus nerka) released from fisheries

Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handling, high water temperature) and natural infections affected the health and longevity of released wild adult sockeye salmon (Oncorhynchus nerka) in British Columbia, Canada. Returning adults were collected before and after entering the Fraser River, yielding marine- and river-collected groups, respectively (N = 185). Fish were exposed to a mild (seine) or severe (gill net) fishery treatment at collection, and then held in flow-through freshwater tanks for up to four weeks at historical (14°C) or projected migration temperatures (18°C). Using weekly nonlethal gill biopsies and high-throughput qPCR, we quantified loads of up to 46 pathogens with host stress and immune gene expression. Marine-collected fish had less severe infections than river-collected fish, a short migration distance (100 km, 5–7 days) that produced profound infection differences. At 14°C, river-collected fish survived 1–2 weeks less than marine-collected fish. All fish held at 18°C died within 4 weeks unless they experienced minimal handling. Gene expression correlated with infections in river-collected fish, while marine-collected fish were more stressor-responsive. Cumulative stressors were detrimental regardless of infections or collection location, probably due to extreme physiological disturbance. Because river-derived infections correlated with single stressor responses, river entry probably decreases stressor resilience of adult salmon by altering both physiology and pathogen burdens, which redirect host responses toward disease resistance.     

One stimulus—Two responses: Host and parasite life‐history variation in response to environmental stress

Climate change stressors will place different selective pressures on both parasites and their hosts, forcing individuals to modify their life‐history strategies and altering the distribution and prevalence of disease. Few studies have investigated whether parasites are able to respond to host stress and respond by varying their reproductive schedules. Additionally, multiple environmental stressors can limit the ability of a host to respond adaptively to parasite infection. This study compared both host and parasite life‐history parameters in unstressed and drought‐stressed environments using the human parasite, Schistosoma mansoni, in its freshwater snail intermediate host. Snail hosts infected with the parasite demonstrated a significant reproductive burst during the prepatent period (fecundity compensation), but that response was absent in a drought‐stressed environment. This is the first report of the elimination of host fecundity compensation to parasitism when exposed to additional environmental stress. More surprisingly, we found that infections in drought‐stressed snails had significantly higher parasite reproductive outputs than infections in unstressed snails. The finding suggests that climate change may alter the infection dynamics of this human parasite.     

Native and invasive hosts play different roles in host–parasite networks

Parasites are often key players in biological invasions since they can mediate the impact of host invasions or can themselves become invasive species. However, the nature and extent of parasite-mediated invasions are often difficult to delineate. Here, we used individual-based, weighted bipartite networks to study the roles (degrees of interactions of individuals in a modular network according to their within- and among-module connections) played by native and invasive host individuals to their parasite communities. We studied two phylogenetically and ecologically close fish species, Mugil cephalus s.l. and Planiliza haematocheilus (Teleostei: Mugilidae). Planiliza haematocheilus is native to the Sea of Japan and invasive in the Sea of Azov whereas, M. cephalus s.l. is native to both seas. Based on the common evolutionary history that drives native host–parasite networks, we hypothesised that 1) native networks have higher modularity than invaded ones; and 2) invasive hosts in the invaded area play a peripheral role to structure parasite communities. We analysed the whole parasite community and subsets based on transmission strategy and host specificity of the parasite species to establish whether modularity and host roles are related to these features in the native and invaded areas. All networks were found to be modular. However, modularity tended to be higher in networks of the native area rather than those of the invaded area. Host individuals of both fish species played similar roles in the native area, whereas invasive hosts played a peripheral role in the networks of the invaded area. We propose that long-term monitoring of the roles of invasive hosts in parasite communities can be a useful proxy for estimating the maturity of the establishment of the invasive hosts in an ecosystem.     

Parasites and invasions: a biogeographic examination of parasites and hosts in native and introduced ranges

Aim To use a comparative approach to understand parasite demographic patterns in native versus introduced populations, evaluating the potential roles of host invasion history and parasite life history. Location North American east and west coasts with a focus on San Francisco Bay (SFB). Methods Species richness and prevalence of trematode parasites were examined in the native and introduced ranges of two gastropod host species, Ilyanassa obsoleta and Littorina saxatilis. We divided the native range into the putative source area for introduction and areas to the north and south; we also sampled the overlapping introduced range in SFB. We dissected 14,781 snails from 103 populations and recorded the prevalence and identity of trematode parasites. We compared trematode species richness and prevalence across the hosts’ introduced and native ranges, and evaluated the influence of host availability on observed patterns. Results Relative to the native range, both I. obsoleta and L. saxatilis have escaped (lost) parasites in SFB, and L. saxatilis demonstrated a greater reduction of trematode diversity and infection prevalence than I. obsoleta. This was not due to sampling inequalities between the hosts. Instead, rarefaction curves suggested complete capture of trematode species in native source and SFB subregions, except for L. saxatilis in SFB, where infection was extremely rare. For I. obsoleta, infection prevalence of trematodes using fish definitive hosts was significantly lower in SFB compared to the native range, unlike those using bird hosts. Host availability partly explained the presence of introduced trematodes in SFB. Main conclusions Differential losses of parasite richness and prevalence for the two gastropod host species in their introduced range is probably the result of several mechanistic factors: time since introduction, propagule pressure, vector of introduction, and host availability. Moreover, the recent occurrence of L. saxatilis’ invasion and its active introduction vector suggest that its parasite diversity and distribution will probably increase over time. Our study suggests that host invasion history and parasite life history play key roles in the extent and diversity of trematodes transferred to introduced populations. Our results also provide vital information for understanding community‐level influences of parasite introductions, as well as for disease ecology in general.     

Synopsis of infectious diseases and parasites of commercially exploited shellfish

The development of shellfish-based industries and the concomitant increase in demand for the introduction and transfer of different shellfish species and stocks has increased the risks of spreading their parasites and diseases around the world. To avoid the accidental introduction of infectious disease agents, information on known parasites and diseases must be readily available. Since the number of recognized infectious agents and facts on known diseases is continuously increasing, it is necessary to update the current state of knowledge. Thus, published and new accounts of viruses, bacteria, protozoa, fungi, metazoa, and infectious diseases of unknown aetiology in commercially exploited shellfish (molluscs, echinoderms, and crustaceans) are summarised. The summaries were devised to be of use to regulatory agencies, diagnosticians, researchers, and students who may require information on this diverse subject. The information is organised according to the host that is normally infected (i.e. oysters, mussels, clams, cockles, scallops, abalone, sea urchins, sea stars, lobsters, shrimp, prawns, crabs, and freshwater crayfish). Each of the 169 summaries includes the common or widely accepted name of the parasite or disease agent, and the scientific name (where known) or taxonomic affiliation. In addition, geographic distribution, host species infected (both naturally and experimentally), impact on host health, diagnostic techniques including illustrations for many of the diseases, known methods of control, and appropriate references are provided.     

Phylogenetic and environmental DNA insights into emerging aquatic parasites: implications for risk management

Species translocation leads to disease emergence in native species of considerable economic importance. Generalist parasites are more likely to be transported, become established and infect new hosts, thus their risk needs to be evaluated. Freshwater systems are particularly at risk from parasite introductions due to the frequency of fish movements, lack of international legislative controls for non-listed pathogens and inherent difficulties with monitoring disease introductions in wild fish populations. Here we used one of the world’s most invasive freshwater fish, the topmouth gudgeon, Pseudorasbora parva, to demonstrate the risk posed by an emergent generalist parasite, Sphaerothecum destruens. Pseudorasbora parva has spread to 32 countries from its native range in China through the aquaculture trade and has introduced S. destruens to at least five of these. We systematically investigated the spread of S. destruens through Great Britain and its establishment in native fish communities through a combination of phylogenetic studies of the host and parasite and a novel environmental DNA detection assay. Molecular approaches confirmed that S. destruens is present in 50% of the P. parva communities tested and was also detected in resident native fish communities but in the absence of notable histopathological changes. We identified specific P. parva haplotypes associated with S. destruens and evaluated the risk of disease emergence from this cryptic fish parasite. We provide a framework that can be applied to any aquatic pathogen to enhance detection and help mitigate future disease risks in wild fish populations.     

Viral infections of aquatic animals with special reference to Asian aquaculture

Worldwide, the number of communicable diseases of animals raised in aquaculture continue to increase. Viral infections of cultivated shellfish, crustacea, and finfish have been frequently recognized in the past few years. In the Asian regions, penaeid shrimp and several teleost fish underwent epizootics associated with heavy losses in aquaculture. Baculoviruses are particularly harmful to shrimp and prawns. Herpes-, irido-, reo-, or rhabdovirus-like agents can cause outbreaks in fish farms. Viral diseases are important limiting factors in the expansion of aquaculture. However, studies on viral infections of aquatic animals have been focused primarily on economically important farmed fish. Therfore, certain viral diseases of teleost fish are relatively well understood. In contrast, our knowledge of viral infections of farmed aquatic invertebrates is still very spare. Although a great number of viruses have been detected in farmed molluscs and crustaceans, the pathogenicity and epizootiology of most of the agents is not known.     

Health management during handling and live transport of crustaceans: a review

Best practice approaches used in the live transport of commercial crustacean species groups are reviewed and the physiological responses to handling practices are described. Codes of practice aimed at providing technological guidelines in handling and transportation of live prawns, lobsters, crabs and freshwater crayfish are examined. While some handling and transport practices are common across species groups, for example purging and chilling, recommended practices vary with species group. The influence of stress responses on health and survival during live transport is discussed and research investigations on the effect of stressors, in particular air exposure, handling and physical disturbances and temperature fluctuations on physiological processes are reviewed for the six species groups, crabs, freshwater crayfish, clawed and spiny lobsters, freshwater prawns and marine prawns. Investigations on the assessment of immune responses to live transport stressors using haemograms, clotting times, phenoloxidase activity, phagocytic activity, bacteremia and antibacterial activity and haemolymph protein concentration are described. A combination of physiological parameters is desirable in the assessment of stress response or health status in crustacean species transported live to seafood markets.     

Parasitic diseases in marine cage culture--an example of experimental evolution of parasites?

Rapid development of fish culture in marine cages has been associated with an emergence of parasitic diseases. There is a general trend to an increase in infections with ectoparasites with direct life cycles and a reduced diversity of parasites in aquaculture. Some mariculture creates conditions that are similar to serial passage experiments, which are used to study adaptation during experimental evolution of pathogens. In particular, increased density of fish, repeated introduction of naive hosts, homogenous host populations, fast growth and a potential decrease in genetic diversity are attributes of both aquaculture and serial passage experiments. Some free-living organisms, for example Neoparamoeba spp. and Uronema spp. parasitise fish in culture, but have not been reported from wild populations. Farming fish in marine cages can increase the risk of outbreaks of parasitic diseases, including those caused by opportunistic parasites. However, aquaculture has the potential to control parasitic diseases through selective breeding, vaccination and general fish health management.     

Species of Mycosphaerellaceae and Teratosphaeriaceae on native Myrtaceae in Uruguay: evidence of fungal host jumps

Mycosphaerella species are well-known causal agents of leaf diseases on many economically and ecologically important plant species. In Uruguay, a relatively large number of Mycosphaerellaceae and Teratosphaeriaceae are found on Eucalyptus, but nothing is known of these fungi on native Myrtaceae. The aim of this study was to identify Mycosphaerellaceae and Teratosphaeriaceae species associated with leaf diseases on native Myrtaceae in Uruguay and to consider whether host jumps by the pathogen from introduced Eucalyptus to native Myrtaceae have occurred. Several native forests throughout the country were surveyed with special attention given to those located close to Eucalyptus plantations. Five species belonging to the Mycosphaerellaceae and Teratosphaeriaceae clades were found on native Myrtaceous trees and three of these had previously been reported on Eucalyptus in Uruguay. Those occurring both on Eucalyptus and native Myrtaceae included Pallidocercospora heimii, Pseudocercospora norchiensis, and Teratosphaeria aurantia. In addition, Mycosphaerella yunnanensis, a species known to occur on Eucalyptus but not previously recorded in Uruguay, was found on leaves of two native Myrtaceous hosts. Because most of these species occur on Eucalyptus in countries other than Uruguay, it appears that they were introduced in this country and have adapted to be able to infect native Myrtaceae. These apparent host jumps have the potential to result in serious disease problems and they should be carefully monitored.     

Size-selective predation by all-male prawns: implications for sustainable biocontrol of snail invasions

All-male populations of the freshwater prawn Macrobrachium rosenbergii were recently produced by a novel temporal RNA interference (RNAi)-based biotechnology for aquaculture purposes. This biotechnology opens the way to the wide use of all-male prawn populations as sustainable biocontrol agents against invading populations of freshwater snails, for which there is currently no environmentally friendly solution. Among the most damaging of the invasive freshwater snail species are the apple snails (Pomacea spp.), which inflict major damage on natural ecosystems and rice fields. The proposed use of all-male prawn populations as environmentally friendly biocontrol agents against invasive freshwater snails has several advantages: efficient predation by the prawns over a wide range of freshwater snails, the ready availability of the prawns, and the monosex non-reproductive nature of the biocontrol agents. Since the aquatic predators are strongly size selective, we quantified the predation rate as a function of body size of both predator and prey (M. rosenbergii and P. caniculata). Medium-sized and large prawns (~10–30 g) efficiently preyed small and medium-sized snails (up to 15 mm), while small prawns (up to 4 g) immediately and completely eradicated snail hatchlings. Medium-sized prawns (~22 g) exterminated a significant fraction of snail biomass within 24 h (up to 58% of their body mass) after being introduced into a tank of snails. A typical ‘climbing-to-the surface’ anti-predator behavior of the snails was recorded. The potential of all-male prawns as efficient biocontrol agents over hatchling and adult apple snails as part of an integrated pest management program is discussed. Our experiments set the stage for evaluating the ecological and economic implications of this generic solution for a wide variety of habitats.     

Coextirpation of host–affiliate relationships in rivers: the role of climate change,water withdrawal,and host‐specificity

The role of climate‐related disturbances on complex host–affiliate relationships remains understudied, largely because affiliate species vary in host use and are often differentially susceptible to disturbance relative to their hosts. Here we report the first set of host–affiliate species–discharge relationships (SDR) in freshwater and examine how anticipated shifts in water availability (flow) will impact coextirpations. We used SDR for freshwater mussels and fish across 11 regions (over 350 rivers) in the continental United States that we coupled to future water availability (2070) to model mussel and fish coextirpations. We also used river‐specific host–affiliate matrices (presence–absence) to evaluate how host‐specificity (mean number of hosts used by an affiliate) and host‐overlap (extent to which affiliates share hosts) relate to extirpation vulnerability. We found that the strength and predictability of SDR models vary geographically and that mussels were more susceptible to flow alterations than fish. These patterns of extirpations were strongest in the southeast where: (1) flow reductions are expected to be greatest; (2) more species are lost per unit flow; (3) and more mussels are expected to be lost per unit of fish. We also found that overall mussel losses associated with reduction in habitat (water availability) were greater than those associated with loss of fish hosts which we assumed to be a function of host redundancy. These findings highlight the utility of SDR as a tool for conservation efforts but they also demonstrate the potential severity of reductions in mussel and fish richness as consequence of climate change and water use. Mussels provide key ecosystem services but face multiple pronged attacks from reductions in flow, habitat, and fish hosts. These losses in biodiversity and ecosystem functions can translate into major effects on food webs and nutrient recycling.     

The Asian Fish Tapeworm Bothriocephalus acheilognathi: a Potential Threat to Native Freshwater Fish Species in Mexico

Introduction of the parasite Bothriocephalus acheilognathi Yamaguti, 1934 with the herbivorous carp Ctenopharyngodon idellus, and other cyprinids, has been documented in almost every continent, except Antarctica. This study presents the current geographical distribution of this cestode in the freshwater fish of Mexico, highlighting infections in autochthonous and endemic species. It compiles existing information and presents original data. B. acheilognathi is widely dispersed among the freshwater fish of Mexico, being recorded to date in 49 fish species from 26 genera, 7 families and 5 orders. B. acheilognathi is reported from Mexico for the first time in Dionda ipni, Notropis celayensis, Yuriria alta, Gambusia vittata, Poecilia butleri, P. mexicana, Poeciliopsis baenschi, Poeciliopsis sp., Cichlasoma cyanoguttatum and C. labridens. The new hosts identified in this study bring the total number of known host species to 102 in 14 families and 7 orders of freshwater fishes around the world. Given its wide distribution among Mexican freshwater fish species, the abundance of the parasite and its high pathogenicity, parasitological data for B. acheilognathi should be considered as an important factor in native fish conservation policies. Biological changes in the freshwater habitats in Mexico caused by the introduction of exotic fish species and their parasites are virtually ubiquitous and extremely difficult to eradicate once established. As such, they should be considered as one of the most serious threats to native fish conservation.     

The distribution of the introduced tapeworm Bothriocephalus acheilognathi in Australian freshwater fishes

Native and exotic fishes were collected from 29 sites across coastal and inland New South Wales, Queensland and Victoria, using a range of techniques, to infer the distribution of Bothriocephalus acheilognathi (Cestoda: Pseudophyllidea) and the host species in which it occurs. The distribution of B. acheilognathi was determined by that of its principal host, carp, Cyprinus carpio; it did not occur at sites where carp were not present. The parasite was recorded from all native fish species where the sample size exceeded 30 and which were collected sympatrically with carp: Hypseleotris klunzingeri, Hypseleotris sp. 4, Hypseleotris sp. 5, Phylipnodon grandiceps and Retropinna semoni. Bothriocephalus acheilognathi was also recorded from the exotic fishes Gambusia holbrooki and Carassius auratus. Hypseleotris sp. 4, Hypseleotris sp. 5, P. grandiceps, R. semoni and C. auratus are new host records. The parasite was not recorded from any sites in coastal drainages. The only carp population examined from a coastal drainage (Albert River, south-east Queensland) was also free of infection; those fish had a parasite fauna distinct from that of carp in inland drainages and may represent a separate introduction event. Bothriocephalus acheilognathi has apparently spread along with its carp hosts and is so far restricted to the Murray-Darling Basin. The low host specificity of this parasite is cause for concern given the threatened or endangered nature of some Australian native freshwater fish species. A revised list of definitive hosts of B. acheilognathiis presented.