Original Description Of Species Research Articles

Morphological data and DNA barcoding reveal the presence of the alien freshwater leech Helobdella octatestisaca (Hirudinida: Glossiphoniformes) in North Africa (Tunisia).

We hereby report the first occurrence of Helobdella octatestisaca in North Africa, specifically in Tunisia, as a likely introduced species from the Neotropical Region. Historically, leeches bearing a prominent chitinous scute on their dorsal surface were commonly diagnosed as H. stagnalis. Most probably, H. octatestisaca had previously been misidentified as H. stagnalis in Tunisia. The identification was primarily based on morphological evidence, supplemented by genetic data obtained from COI DNA barcoding. The morphology of the examined specimens was consistent with the original species description, notably characterized by the presence of four pairs of testisacs. To support our findings, we conducted a phylogenetic analysis using the Maximum Likelihood method based on COI alignment constructed with the newly obtained sequence from Tunisian specimens and complete or nearly complete 'Folmer fragment' sequences of congeners sourced from the GenBank database. This study highlights the first identification of H. octatestisaca in North Africa and suggests that previous records of H. stagnalis in Tunisia likely misidentified this species.

Integrative taxonomy of the featherback fish genus Chitala (Osteoglossomorpha: Notopteridae) in Peninsular Malaysia

AbstractThe taxonomy of the freshwater featherback fish genus Chitala (Osteoglossomorpha: Notopteridae) remains unsettled because delimiting and naming Chitala species based solely on morphology led to different hypotheses. In this study, we aim to determine the number and identity of Chitala species present in Peninsular Malaysia by employing an integrative taxonomic approach that combines morphology and two mitochondrial markers: the cytochrome c oxidase subunit I (COI) and cytochrome b genes. A total of 60 specimens of Chitala were collected throughout Peninsular Malaysia. Initially, all specimens were sorted into three distinct categories based on their body marking patterns. A molecular phylogenetic analysis revealed that each of these groups was monophyletic, and an automated species partition method further recognized them as distinct species. These results support the presence of three Chitala species in Peninsular Malaysia, even though a multivariate morphometric analysis failed to fully differentiate each of these three species. Comparison with original species descriptions and genetic data from an additional 70 Chitala specimens from neighbouring regions allowed us to name these species as Chitala lopis, Chitala borneensis, and Chitala ornata. We also showed the presence of two undescribed species in Indonesia.

A catalogue and redescription of type specimens of fireflies (Coleoptera, Lampyridae, Luciolinae) deposited in Naturalis Biodiversity Center, Leiden

Type specimens of flashing fireflies (Coleoptera, Lampyridae, Luciolinae) in the Naturalis Biodiversity Center, Leiden (RMNH) collection were documented. Specimens explicitly marked or indicated as types belonging to the lucioline fireflies were investigated with each specimen and its accompanying labels photographed, and its morphological characters analysed and compared with the original species description. The genitalia dissections of selected types enabled redescription and clarification of the taxonomic status of seven name-bearing type specimens. This study provides the first redescriptions of holotypes, designation of lectotypes for five species, and confirmation that two of these belong in the genus Luciola s. str. A lectotype and paralectotype were designated for two specimens of Luciola cerea Gorham, 1882 which is confirmed to belong to the genus Curtos Motschulsky, 1845. Atyphella testaceolineata Pic, 1939 was redescribed and figured based on the holotype (an incomplete specimen). We assigned Luciola laticollis Gorham, 1883 and Luciola nicollieri Bugnion, 1922 to Luciola sensu stricto and Luciola picea Gorham, 1882 to species inquirenda. The identity of Pteroptyx decolor Olivier, 1911 is finally confirmed as a close Indonesian relative of Pteroptyx valida Olivier,1909 and a lectotype is designated. In addition, we take the first opportunity to present pictures of the original holotype of Pygoluciola stylifer Wittmer, 1939. We also discuss the challenges taxonomists face in identifying specimens and how detailed dissections allow us to present descriptions of certain male features not previously addressed.

Taxonomy of the two nominal species of the deep-sea clawed lobsters Nephropsis serrata Macpherson, 1993 and N. hamadai Watabe & Ikeda, 1994 (Decapoda: Astacidea: Nephropidae)

Abstract The deep-sea clawed lobster Nephropsis hamadai Watabe & Ikeda, 1994, described from Japan, has been suspected to be a synonym of Nephropsis serrata Macpherson, 1993, recorded from Australia (type locality) to Taiwan. The availability of recently collected material from Japan referred to N. hamadai allowed detailed morphological and molecular comparisons of topotypic specimens of N. serrata and N. hamadai. Re-examination of the holotype of N. serrata revealed that the major difference proposed for separating N. hamadai from N. serrata was based on an error in the original description of the latter species. As there are very low genetic divergences and no morphological differences between the Australian and Japanese materials referable to N. serrata and N. hamadai, these two names are now confirmed to be synonyms.

New morphological data for two rare species of sand-dwelling marine dinoflagellates, Amphidiniella sedentaria and Pachena cf. leibnizii

Abstract Benthic dinoflagellates have been the subject of extensive taxonomic research in recent decades. Studies of morphologies of already known species of benthic dinoflagellates from various geographical populations remain relevant, as these allow elucidation of some details that were overlooked in the original species descriptions or assessment of their morphological variability. In the present study, two rare species of dinoflagellates, Amphidiniella sedentaria and Pachena cf. leibnizii, have been studied, for the first time, from coastal sands of the northwestern Sea of Japan. In the cells of A. sedentaria from the Sea of Japan, we have found two anterior intercalar plates instead of one. Therefore, the original formula has been changed to APC 4′ 2a 7″ 5c 4s 6‴ 2⁗. As a result of the examination of P. cf. leibnizii from the Sea of Japan, we have counted seven precingular plates and six cingular plates, instead of six and five, respectively, indicated in the original description. The plate formula of the cells of P. cf. leibnizii from the Sea of Japan is APC 4′ 3a 7″ 6c 5s 5‴ 2⁗. It is currently difficult to judge whether these differences are morphological variations. Therefore, we have identified these cells as P. cf. leibnizii.

A new cryptic species of Australian Glyptotermes (Isoptera: Kalotermitidae) discovered by effective use of morphological characteristics of primary reproductives

AbstractClosely related species within termite genera often show extremely similar morphology, where morphological characteristics of soldiers alone or imagos (including alates and primary reproductives) alone are sometimes insufficient to establish new species. However, many original descriptions of termite species are based on soldier characteristics alone, because of the seasonal occurrence of alates and the difficulty in collecting primary reproductives. Importantly, primary reproductives of the family Kalotermitidae (so‐called drywood termites) are relatively easy to collect from field colonies compared with those of the other termite families. Here, we describe a new kalotermitid species, Glyptotermes matsuurai sp. nov., from Australia by effective use of morphological characteristics of primary reproductives. Glyptotermes matsuurai is distinguished from the Australian species G. iridipennis Froggatt, 1896 by the mitochondrial cytochrome c oxidase subunit II gene; however, it is not distinguishable from G. iridipennis based on the external morphology of soldiers. It therefore forms a species complex with G. iridipennis. Although we could collect alates of G. matsuurai from only one of the field‐collected colonies kept in the laboratory, we conducted morphological analyses of imagos from multiple colonies by using primary reproductives collected from field colonies. As a result of our morphological analyses of imagos, we found that G. matsuurai is morphologically distinguishable from all other species of Australian Glyptotermes. Thus, when enough alates are unavailable, morphological characteristics of primary reproductives can be used to facilitate the discovery of undescribed cryptic species at least in the genus Glyptotermes and possibly in other genera within the family Kalotermitidae.

Review of the Costa Rican Saltagenes Diller, 1995 (Hymenoptera: Ichneumonidae: Ichneumoninae: Phaeogenini) with descriptions of seven new species.

The parasitoid wasp genus Saltagenes Diller, 1995 is known only from the original description of a single species from Argentina. However, undescribed Saltagenes species occur throughout the Neotropical region and into the southern Nearctic. Here, I review the Saltagenes species of Costa Rica and describe seven new species: Saltagenes alboannulatus sp. nov., S. atrosomus sp. nov., S. escazuensis sp. nov., S. gauldi sp. nov., S. modicum sp. nov., S. pseudatrosomus sp. nov., and S. rotundiceps sp. nov. The generic diagnosis is revised to account for hitherto unknown morphological diversity of Saltagenes. An illustrated key and specimen images are provided to aid in identification. Saltagenes is now represented by eight described species though more than double that figure remain undescribed from outside of Costa Rica. More broadly, this study highlights the paucity of our knowledge of Costa Rican Ichneumoninae.

Orophilic and crenophilic stoneflies (Insecta: Plecoptera) of the Italian region: new species, nomenclatural changes, updated and annotated checklist

An updated checklist of 191 Plecoptera species currently known from the Italian region is presented. Four new species are described: Protonemura marilouae sp. nov. from Calabria and Sicily, P. olahi sp. nov. from the central Apennines (Abruzzi), Leuctra stronensis sp. nov. from the Pennine Alps and L. trecimensis sp. nov. from the Dolomites. The males of Protonemura hirpina Consiglio, 1958b, and Leuctra silana Aubert, 1953b, are re-described, and their females are described for the first time. Four taxa are raised from subspecies to species rank: Protonemura padana Vinçon & Ravizza, 2005, Leuctra aubertorum Ravizza & Ravizza Dematteis, 1994a, L. orsiera Ravizza & Vinçon, 2003 and L. incudensis Vinçon & Ravizza, 2000b. Nemoura banatica Kis, 1965 is restored as a valid species, removed from synonymy with N. marginata Pictet, 1836, and its male is re-described. Protonemura beatensis robusta Berthélemy, 1963 is declared to be a junior synonym of P. salfii (Aubert, 1954c). Taxonomical notes on problematic species are added. The present checklist is the result of the compilation of published and unpublished data collected by the first three authors between 1974 and 2023. Distribution, altitudinal range and flight period of all species are summarized in table I. The altitudinal limits of nearly all orophilic Plecoptera species of the Italian Alps and Apennines are shown to have shifted to higher altitudes over a period of 30 or more years. An exhaustive bibliography of the original species descriptions of the Italian Plecoptera fauna is provided.

A new distribution record, first host plant record and DNA barcoding of the Neotropical micromoth Astrotischeriakarsholti Puplesis & Diškus (Lepidoptera, Tischeriidae).

Astrotischeria Puplesis & Diškus, 2003 (Lepidoptera, Tischeriidae) is a New World genus of micromoths whose larvae are leaf miners associated mainly with plants of the family Asteraceae. The original description of the type species Astrotischeriakarsholti Puplesis & Diškus, 2003 was based on adults from central Peru. No additional distribution records, host plants or DNA barcodes have been documented for this species. Astrotischeriakarsholti is reported for the first time from Chile, based on adults obtained from leaf mines of Ambrosiacumanensis Kunth (Asteraceae) collected in the transverse valleys of the Atacama Desert. This discovery expands the distribution range of this micromoth nearly 900 km to the southeast and represents its first host plant record. Divergence between DNA barcodes of A.karsholti and the nearest congeneric was 6% (K2P). A Maximum Likelihood analysis, based on DNA barcodes, raises questions about the monophyly of Astrotischeria.

Response to Britz (2022) regarding the validity of the giant sunfish Mola alexandrini (Ranzani, 1834) (Teleostei: Molidae).

The small family of ocean sunfishes has a long and complicated taxonomic and nomenclatorial history dating back several centuries. Most recently, Britz (2022) questioned the validity of Mola alexandrini (Ranzani, 1839) as the valid name for Mola sp. A sensu Yoshita et al. (2009). Specifically, he questioned the authenticity of the purported Orthragoriscus alexandrini holotype rediscovered by Sawai et al. (2018) due to uncertainties regarding the original units of measurement, along with discrepancies between the original illustration and the purported holotype. He also questioned the reliability of the illustration to reflect the fresh morphology, and the adequacy of the species description (sans illustration and holotype) to link it to any of the currently recognized Mola species. In summary, Britz (2022) opined that M. alexandrini is a species inquirenda. Here we respond to Britzs concerns with the findings from an additional literature review. Firstly, the original species description appears to give measurements in Parisian units, yielding a discrepancy in length with the purported holotype within human error. However, due to various uncertainties, length does not appear to be a robust piece of evidence to neither confirm nor refute the specimens authenticity. Secondly, the morphological differences between the original illustration and the purported holotype were found to be within the expected level of accuracy for Mola illustrations at the time, by both Ranzani and others. Thirdly, a contemporaneous publication describes how Ranzani himself bought the specimen which became the Or. alexandrini holotype, suggesting he would likely have seen it in its fresh state, rendering it unlikely he would have produced a species description and illustration incongruent with this. Fourthly, re-examining the original species description suggests this provides adequate and sufficient information to link Or. alexandrini to Mola sp. A, even in the absence of a holotype. Finally, during this review, we came upon an even older paper describing Or. alexandrini, and we conclude that the currently valid name for Mola sp. A sensu Yoshita et al. (2009) is Mola alexandrini (Ranzani, 1834).

Original descriptions of Palaearctic species of the genus Plateumaris C. G. Thomson, 1859 (Coleoptera, Chrysomelidae, Donaciinae) and their translations.

Many original descriptions of beetles were published in Latin with specific idioms and technical terms, which are sometimes difficult to understand. The exact meaning of these descriptions is necessary for taxonomic and systematic research. Of the ten Palaearctic Plateumaris species regarded as valid three were described in English, the remaining seven in Latin, French, or German: P.amurensis Weise, 1898, P.bracata (Scopoli, 1772), P.consimilis (Schrank, 1781), P.roscida Weise, 1912, P.rustica (Kunze, 1818), P.sericea (Linnaeus, 1758), and P.weisei (Duvivier, 1885). These seven non-English original descriptions and their translations into English are presented here. Additionally, the translations of the first descriptions of the genus Plateumaris and of its 19 synonyms (some were described in Russian, also) are given.

Hiding in the Arctic and in mountains: a (dis)entangled classification of Claxtonia (Heterotardigrada: Echiniscidae)

Abstract Numerous evolutionary lineages representing an armoured, limno-terrestrial family Echiniscidae are restricted to high mountainous or polar localities, exhibiting clear cold stenothermic preferences. One such group is the genus Claxtonia, with its type species Claxtonia wendti, originally described from Svalbard and later on reported globally. In this paper, we re-describe this taxon by establishing the neotype from Spitsbergen. We sequenced five genetic markers (18S rRNA, 28S rRNA, ITS-1, ITS-2, and COI) for multiple populations of Claxtonia, including C. mauccii, C. molluscorum, C. wendti, and several potentially new species, collected in the Alps, Andes, Carpathians, Scotland, Iceland, Southern Appalachians, Spitsbergen, Scandinavian Peninsula, Borneo, and the West Indies. The relationships between these species are elucidated thanks to the phylogenetic reconstructions based on nuclear loci. Various Claxtonia species frequently co-occur in mosses and lichens, which hampers delineating their probable geographic ranges. All historical records of C. wendti are questioned in the light of our revision. Delineation of new species within the genus is nipped in the bud due to numerous problems with original species descriptions, unknown intraspecific (including ontogenetic) variability, and the lack of DNA barcodes. Finally, it is hypothesized that Claxtonia potentially comprises two lineages: a cold-stenothermic one and a thermophilic subtropical–tropical one.

Amanita thiersii and Amanita foetens are closely related but genetically and geographically distinct species, leaving the origins of A. thiersii and its range expansion enigmatic

Background: The decomposer Amanita thiersii was originally described from a Texas lawn. Over time the species appears to have spread its range, but whether A. thiersii is an introduced and invading fungus or a native expanding its range remains an open question. A striking morphological similarity between A. thiersii and the Argentinian A. foetens led us to question whether the two species are the same. We hypothesized A. thiersii was simply an A. foetens introduced from Argentina. Methods: We first compared the original species descriptions of both taxa. Next, we used databases associated with iNaturalist and Mushroom Observer to plot the global ranges of A. thiersii and A. foetens, revealing new reports of A. thiersii in Mexico and an expanded range in the United States of America. Next, we sequenced three genomes: an A. thiersii specimen from the U.S.A., an isotype of A. foetens, and an Argentinian specimen tentatively identified as A. thiersii. We reconstructed phylogenies using our own and publicly available data of other Amanita species. Because the genetic diversity of A. thiersii in the U.S.A appears to be very low, we also searched for mating type loci. Results: Macroscopic descriptions suggest the two taxa are distinguishable by mushroom stature and the decoration of the stipe. The geographic ranges of the two taxa seem distinct and not overlapping, although the inconsistent names used by database users causes confusion. Phylogenies suggest the genomes of mushrooms collected in U.S.A. are different from Argentinian genomes. We discovered an individual which appears to have a mating type locus present in one nucleus of the dikaryon and absent from the second nucleus. Conclusions: While A. thiersii and A. foetens appear strikingly similar, each is morphologically, geographically and genetically distinct, leaving the question of whether A. thiersii is native or introduced to the U.S.A. unanswered.

RAJONCHOCOTYLE CERFONTAINE, 1899 (MONOGENEA: HEXABOTHRIIDAE) SPECIES FROM SOUTH AFRICA, WITH DISCUSSION OF THE LITERARY ACCOUNTS OF R. EMARGINATA (OLSSON, 1876).

Rajonchocotyle Cerfontaine, 1899, species are blood-feeding parasites on the gills of rajiforms. Eight species are considered valid, the most recent of which was described just after World War II. Many of the original descriptions of Rajonchocotyle species are limited in diagnostic value, and comparative museum material is scanty. The genus requires revision, and in support thereof, we provide detailed redescriptions for Rajonchocotyle albaCerfontaine, 1899, from the type host Rostroraja alba (Lacepède, 1803) and Rajonchocotyle emarginata (Olsson, 1876), Sproston, 1946, from 2 new host records, Raja straeleni Poll, 1951, and Leucoraja wallacei (Hulley, 1970), from South Africa, a new locality record. The generic diagnosis for Rajonchocotyle is amended to include greater details of the male reproductive system and confirms Paul Cerfontaine's and Nora Sproston's historic observations of the morphology of the male copulatory organ consisting of a separate proximal seminal vesicle and a distal cirrus. The lectotype of Rajonchocotyle kenojeiYamaguti, 1938, is assigned, and a comprehensive Rajonchocotyle-host species list is provided, highlighting species records that require further verification, and the purported global host range of R. emarginata is discussed.

A new species of Arenallianassa (Decapoda: Axiidea: Callianassidae) from hydrothermal vents with notes on its ecology and a redescription of Arenallianassa arenosa (Poore, 1975)

The hitherto monotypic genus Arenallianassa Poore, Dworschak, Robles, Mantelatto and Felder, 2019 is revised following the discovery of a new species, Arenallianassa katrinae sp. nov. from New Zealand and Tonga. The original description of the type species Arenallianassa arenosa (Poore, 1975) is augmented. The new species has been found in localised high abundance in the vicinity of shallow (111–181 m depth) hydrothermal vents at each end of the Kermadec–Tonga Volcanic Arc system. This brings the number of callianassoids in New Zealand to six.

Morphological and Molecular Characterization of Diplogasteroides sp., a Cryptic Population of the Haslacheri Group (Diplogastridae), and Parasitorhabditis terebranus (Rhabditidae) from Korea.

Diplogasteroides sp., a cryptic population of D. haslacheri, and Parasitorhabditis terebranus were reported from the frass of Monochamus alternatus galleries in dead Pinus thunbergii for the first time in Korea. Females and males are morphologically characterized and their linked DNA barcodes (18S-rRNA, 28S-rRNA, ITS-rRNA and COI) supplied. Females and males of the two species from Korea conform to the original species descriptions from Europe and the USA, with variations in a few details in morphometrics. Specifically, Diplogasteroides sp. is morphologically very similar to D. haslacheri. However, it cannot be designated as D. haslacheri due to the existence of cryptic species complex within the haslacheri group (D. haslacheri, D. asiaticus, D. nix, D. andrassyi, and D. carinthiacus), a condition requiring hybridization studies to test species identity within the group. Based on analysis of COI sequences, differences among these cryptic species are evident. Thus, in addition to hybridization tests, the COI might be a powerful DNA barcoding marker for the precise identification of these cryptic species within the genus. Additionally, this is the first molecular characterization of P. terebranus, and the species is herein recorded for the first time outside its type locality.

Faunistic and taxonomic notes on some Madagascan Muscidae (Diptera) and descriptions of three new species

About 220 Muscidae collected from various locations in Madagascar and belonging to the subfamilies Azeliinae, Muscinae, Mydaeinae and Phaoniinae have been identified. Several specimens of the previously unknown female of Graphomya rossi Zielke, 1974 were found among the material. The female’s taxonomic characters are described in detail, also taking into account the intraspecific variability of some features of the females. The identification of the specimens of Hydrotaea bella Couri, Pont and Penny, 2006 led to the correction of a wrongly described taxonomic feature in the original species description. The notopleura of H. bella are not bare, as stated by the authors, but are covered with several dark setulae. Three species proved new to science and are described as Gymnodia malagasya spec. nov., Helina amboa spec. nov. and Helina hesitancia spec. nov. This means that six Gymnodia and eleven Helina species are now recorded from Madagascar.

First record of the Fiddler Crab, Minuca osa from the Eastern Montijo Gulf, Panama

Minuca osa had been previously thought to be endemic to Pacific Costa Rica (Golfo Dulce). However, specimens fitting the description were sampled in April 2021 and August 2022 in two sites in the Eastern Montijo Gulf, Panama. Based on the morphological character correspondence between the specimens collected and the original species description, it can be concluded that Minuca osa is also present in the Eastern Montijo Gulf.

First report of Fusarium commune causing root rot of soybean seedlings in Indiana.

In the summer of 2020, 127 soybean [Glycine max (L.) Merr] seedlings (V1-V3 stage) with reduced growth vigor were sampled as part of a bulk collection of seedling pathogens from Purdue's Agronomy Center for Research and Education in West Lafayette, Indiana. After rinsing off soil, one plant displayed prominent necrotic lesions on both cotyledons and the hypocotyl and rot of the roots. Root tissue segments measuring roughly 5 mm in length and adjacent to lesions were excised and surface sterilized in 0.6% NaOCl for 10 min, then in 70% ethanol for 2 min, rinsed thrice in sterile distilled H2O, and plated on dichloran-chloramphenicol-peptone agar (Andrews and Pitt 1986). Single-spore cultures were produced and grown on potato dextrose agar. The isolate (AC101) developed white aerial mycelium, rings of magenta coloration in the media, and pale orange sporodochia with age. Microscopic observation of two-week-old cultures grown on synthetic low-nutrient agar (NRRL Medium No. 4) in the dark at 28°C revealed 2-3 septate falcate macroconidia measuring 17.1 - 43.9 × 2.8 - 3.5 µm (avg. 29.4 × 3.1 µm, n=20); 0-1 septate straight to slightly curved microconidia measuring 3.9 - 8.6 × 1.9 - 2.5 µm (avg. 7.0 × 2.2 µm, n=20); and round chlamydospores borne singly or doubly with diameter measuring 6.1 - 14.2 µm (avg. 8.9 µm, n=20). These characteristics were consistent with descriptions of Fusarium commune K. Skovg., O'Donnell & Nirenberg (Skovgaard et al. 2003). DNA was extracted from aerial mycelium and the internal transcribed spacer (ITS) region using ITS1/ITS4 primers (White et al. 1990) (GenBank accession MW463361), the mitochondrial small subunit (mtSSU) rDNA using MS1/MS2 primers (White et al. 1990) (MW466537), and the translation elongation factor 1-alpha (TEF1α) gene using 983F/1567R primers (Rehner and Buckley 2005) (MW475296) were amplified and sequenced. Blast searches in GenBank showed that these sequences had 100% identity with corresponding sequences of F. commune (ITS: MN452698; mtSSU: AF362277; and TEF1α: KU171720). The matching mtSSU sequence was an accession from the original species description (Skovgaard et al. 2003). A pathogenicity test was conducted under greenhouse conditions (20-29°C, avg. 24°C) following the infested soil protocol of Ellis et al. (2013a). Ten seeds (cv. Williams) each were used in inoculated and mock-inoculated control treatments with one seed per foam cup. Root rot symptoms similar to, but more destructive than those observed in the field, were observed 14 days after planting on all inoculated plants but not on controls. Inoculated plants reached VE stage compared to controls which reached VC. Disease symptoms included severe necrotic lesions on the cotyledons, dark brown rot of the developing tap root, and brown hypocotyl lesions similar to field symptoms. F. commune was successfully reisolated from inoculated plants, but not from controls, as described above. F. commune has been reported to cause soybean root rot in China (Chang et al. 2018), Korea (Choi et al. 2020), as well as Iowa (Ellis et al. 2013b). To our knowledge this is the first report of F. commune infecting soybean seedlings in the state of Indiana. The expanded distribution of this soybean pathogen warrants heightened attention for its control.

First Record of the Rare Species Aeromonas lusitana from Rainbow Trout (Oncorhynchus mykiss, Walbaum): Comparative Analysis with the Existing Strains.

The species Aeromonas lusitana was first described in 2016 with five strains recovered from untreated water and vegetables from Portugal. Since then, no further records exist of this species. During a surveillance study on the presence of Aeromonas in fish farms in Mexico, a new strain (ESV-351) of the mentioned species isolated from a rainbow trout was recovered. It was identified because it clustered phylogenetically with the type strain of A. lusitana based on the analysis of the rpoD gene sequences. In the present study, phenotypic characteristics, antimicrobial resistance profiles, and the presence of putative virulence genes of this novel strain (ESV-351) were determined in parallel to the five isolates from the original species description. Phenotypic differential characteristics exhibited by A. lusitana ESV-351 depicted an evident similarity to the characteristics exhibited by the other evaluated strains. However, the novel strain was positive for the production of indole using conventional methods, while the rest of the strains, including the type strain, were negative for its production. Furthermore, intermediate resistance to ampicillin, amoxicillin-clavulanic acid and cephalothin was detected in both the novel and the type strain. Five different virulence-related genes were detected in the novel strain and in the previously described strains, with the type strain exhibiting the highest number of virulence-related genes. In addition to this, the genome of the novel strain (ESV-351) was sequenced and compared with the genomes from the type strain (A. lusitana CECT 7828T) and other Aeromonas spp. The genomic analysis defined Aeromonas tecta as the closest species to A. lusitana with a highly similar number of predicted proteins. The genomic size, the number of protein-encoding genes and the number of different tRNAs, among other characteristics, make it possible to propose that the ESV-351 strain could potentially have the capacity to adapt to different environments. Genome comparison of the ESV-351 strain with the type strain revealed that both possess a similar sequence of the citrate synthase gene. In addition to this finding, the chromosomal region containing the citrate synthase locus of the novel strain exhibits some similarity to the chromosomal region in the genome of the A. hydrophila type strain and other known human pathogens, such as Vibrio cholerae. This could suggest a possible virulence role for the citrate synthase gene in A. lusitana (ESV-351).