An updated Atlas of Helophorus chromosomes.

An account is given of my development of techniques to obtain well-spread Giemsa-stained banded chromosome preparations. Apparent G-banding could be obtained following very slight trypsin treatment of freshly prepared slides, but this banding was very fine (close-grained) and possibly not a reflection of chromosome structure. However, treatment of developing embryos in vitro with 5-fluorouridine produced a similar chromomere banding, which is therefore regarded as genuine. Steady accumulation of Helophorus Fabricius, 1775 karyotypes has resulted in the production of an Atlas covering 62 of the 170 species known to occur in the Palaearctic. Chromosome polymorphisms involving pericentric inversions and addition of extra C-banding regions have been found, as well as small B-chromosomes in a few species. In general, karyotypes have proved very useful in establishing the limits of individual species. Parthenogenesis involving triploidy has been found in two species. Karyotypes of experimentally produced hybrids have revealed irregularities in chromosome condensation.

Supplemental Learning in Respiratory Physiology for Healthcare Professionals Towards Successful Treatment of COVID-19.

The immunological and pathophysiological response to COVID-19 can cause severe respiratory impairment affecting gas exchange and lung mechanics. Such was the scale of the respiratory support needed during the first wave of the pandemic, that recruitment of non-respiratory clinical staff was essential to help deal with the growing number of cases. It quickly became apparent that it was vital to rapidly equip these healthcare professionals with appropriate physiological knowledge and practical skills if therapies were to be applied effectively. Furthermore, the unravelling of unusual clinical features of COVID-19, further highlighted a need for knowledge of long-established principles of respiratory physiology. An online digital educational resource, or "respiratory learning tool kit" was developed with interactive material including visualisations, animations, and pathophysiological examples to facilitate understanding. The learning outcomes were centred on physiological principles, essential for understanding the pathophysiology relating to COVID-19, and management and treatment. Topics included principles of gas exchange, gas transport, homeostasis and central control of respiration. These basic physiological principles were linked to pathophysiology and clinical skills around oxygen administration and non-invasive supports such as Continuous Positive Airway Pressure (CPAP). From the degree of engagement and evaluation comments, it was clear that the resource successfully achieved its aim-to increase physiological knowledge and its practical understanding, enabling healthcare professionals to practice with confidence in such an uncertain environment.

A re-examination of the West European species of Boreonectes Angus, 2010, with particular reference to B. multilineatus (Falkenström, 1922) (Coleoptera, Dytiscidae).

The West European species of Boreonectes Angus, 2010 are reviewed. B. multilineatus (Falkenström, 1922) is shown to be widely distributed in the Pyrenees, where it is the only species known to occur. The chromosomes of all five west European species are found to have, in addition their different numbers of chromosomes, differences in the number and locations of secondary constrictions, and in some cases, the number of chromosomes with clear centromeric C-bands. The level of differences between the chromosomes of the species is in stark contrast with the very slight genetic (DNA) differences between them and this suggests that chromosome differentiation may have been a driver of speciation. Two of the species, B. griseostriatus (De Geer, 1774) and B. multilineatus, have distributions extending northwards as far as Arctic Scandinavia. It is pointed out that, while these northern areas now constitute the major portions of their ranges, they must be of fairly recent origins as most of the area would have been covered by ice sheets and therefore not habitable during the glacial maximum of the Last Glaciation. This contrasts with the situation in the area of the Central European mountains where fossil faunas, including Boreonectes, are known. B. griseostriatus, identifiable to species by its parameres, was present in the Woolly Rhinoceros site at Starunia in the Western Ukraine, and this fauna is discussed as well as an English fauna of similar age.

Experience of telehealth in people with motor neurone disease using noninvasive ventilation.

INTRODUCTION: Evidence is emerging that telehealth provides timely and cost-effective support for individuals with motor neurone disease (MND). However, little is known about the subjective experience of using telehealth. This study was designed to examine the experiences of using telemonitoring in patients with MND on noninvasive ventilation (NIV). METHODS: Semi-structured interviews were conducted with seven patients (five males; mean age = 63 yrs; median illness duration = 14 m), who used a telemonitoring device for 24 weeks. Caregivers were present at five of the interviews; they supported communications and provided their feedback. Interviews were audio recorded and transcribed verbatim. Thematic analysis was conducted to find overarching themes. RESULTS: Five themes were identified: Benefits of Timely Intervention, Reducing the Unnecessary, Increased Self-Awareness, Taking Initiative, and Technical Challenges. Overall, timely interventions were observed as a result of regular monitoring, contributing to both physical and psychological well-being of the participants. The patient-caregiver dyads suggested that telemonitoring could reduce costs, save time and ameliorate hassles associated with attending hospital appointments. Participants articulated that telemonitoring enabled symptom awareness and interpretation; the device also enabled the participants to raise concerns and/or requests to the healthcare professionals via the messaging system. Participants confirmed that the telemonitoring device was easy to use, despite some technical issues. CONCLUSIONS: Telemonitoring was positively experienced. The findings suggest this approach is empowering and effective in promoting patients' well-being, while potentially reducing unnecessary clinical contact.Implications for RehabilitationCare for people with MND demands a flexible approach to accommodate the diversity of clinical needs and relentless physical deterioration.Telehealth allows clinicians to provide person-centred care for everyone with MND through frequent monitoring.Holistic and rehabilitative service facilitated by telehealth is generally acceptable and preferred to routine appointments among MND NIV patients.Telehealth promotes time efficient engagement with professionals that leads to symptom awareness and interpretation, while benefiting physical and psychological well-being of MND NIV patients.

Evidence That Higher Temperatures Are Associated With a Marginally Lower Incidence of COVID-19 Cases.

Seasonal variations in COVID-19 incidence have been suggested as a potentially important factor in the future trajectory of the pandemic. Using global line-list data on COVID-19 cases reported until 17th of March 2020 and global gridded weather data, we assessed the effects of air temperature and relative humidity on the daily incidence of confirmed COVID-19 local cases at the subnational level (first-level administrative divisions). After adjusting for surveillance capacity and time since first imported case, average temperature had a statistically significant, negative association with COVID-19 incidence for temperatures of -15°C and above. However, temperature only explained a relatively modest amount of the total variation in COVID-19 cases. The effect of relative humidity was not statistically significant. These results suggest that warmer weather may modestly reduce the rate of spread of COVID-19, but anticipation of a substantial decline in transmission due to temperature alone with onset of summer in the northern hemisphere, or in tropical regions, is not warranted by these findings.

Implementation of a computer-guided consultation in the assessment of suspected obstructive sleep apnoea syndrome.

BACKGROUND: We describe implementation of a clinical decision support system, a computer-guided consultation (CGC), in the assessment of subjects referred with suspected obstructive sleep apnoea syndrome (OSAS). METHODS: Two cohorts of patients were assessed. The first 100 cases had data collected with the CGC by a specialist sleep physician (stage1). A further 100 cases were assessed by a nonspecialist using the CGC (stage 2). For each case, the diagnosis suggested by the CGC was compared with the final diagnosis made by a second specialist sleep physician blinded to the CGC diagnosis. RESULTS: Stage 1: of 100 people evaluated, a final diagnosis of OSAS was made by both the sleep specialist and CGC in 88% of cases. In 7 of the remaining 12 cases, both agreed there was "No evidence of OSAS"; in 5 cases the CGC did not reach a final diagnosis instead prompting specialist referral. Stage 2: 100 people were evaluated; 95% were evaluable. Both CGC and the sleep specialist made a diagnosis of OSAS in 83 cases (87%), in 5 cases both agreed there was no OSAS, whereas in 7 cases the CGC prompted a specialist review due to unexplained symptoms. The CGC was concordant with the final diagnosis in 95% and 93% of cases in the two cohorts, respectively and where there was doubt, prompted for clinical review. No OSAS cases were overlooked by the CGC. CONCLUSION: An intelligent CGC program creates opportunities in sleep medicine management pathways to safely yet effectively utilise nonspecialists working under specialist supervision.

Triploidy in Chinese parthenogenetic Helophorus orientalis Motschulsky, 1860, further data on parthenogenetic H. brevipalpis Bedel, 1881 and a brief discussion of parthenogenesis in Hydrophiloidea (Coleoptera).

The chromosomes of triploid parthenogenetic Helophorus orientalis Motschulsky, 1860 are described from material from two localities in Heilongjiang, China. 3n = 33. All the chromosomes have clear centromeric C-bands, and in the longest chromosome one replicate appears to be consistently longer than the other two. The chromosomes of additional triploid parthenogenetic H. brevipalpis Bedel, 1881, from Spain and Italy, are described. In one Italian population one of the autosomes is represented by only two replicates and another appears more evenly metacentric than in material from Spain and the other Italian locality. Parthenogenetic and bisexual specimens of H. orientalis are illustrated, along with Pleistocene fossil material. Parthenogenetic H. brevipalpis is also illustrated. Parthenogenesis in Hydrophiloidea is discussed. It appears to be rare and, in all cases has been detected by chromosomal analysis of populations in which males are unexpectedly scarce. Parthenogenesis is suspected in Helophorus aquila Angus et al., 2014, from northern Qinghai (China), which should be verified in further studies.

Incorporating self-reported questions for telemonitoring to optimize care of patients with MND on noninvasive ventilation (MND OptNIVent).

Objective: Previous studies suggest a positive impact of telehealth in the care of people with motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). This study reports the development of self-reported questions for telemonitoring, using a tablet-based device Careportal®, in the care of patients with MND on noninvasive ventilation (NIV) and its initial impact. Methods: The study consisted of a question development phase and an evaluation phase of the use of Careportal®. The development phase employed a modified Delphi process. The evaluation phase involved a 24-week pilot study with 13 patients (median age = 66; median illness duration = 14 m), who were using NIV. The participants completed overnight oximetry and self-report questions via Careportal® each week, generating interventions where required. Patient-ventilator interaction (PVI) data were monitored and the revised ALS functional rating scale (ALSFRS-R) was completed. Results: Telemonitoring encompassing the newly developed 26-item symptom questions showed good feasibility and validity. During the evaluation phase, 61 interventions were made for 10 patients, including seven patients who had routine clinic appointments during the trial to optimize care. ALSFRS-R showed significant illness deteriorations. Blood oxygen saturation (SpO2) levels were maintained, time ventilated and inspiratory pressures increased during the trial. Conclusions: The MND OptNIVent question set together with weekly ventilator and oximetry monitoring facilitated the maintenance of ventilation and SpO2 levels despite illness progression. The use of the question set, and devices, such as Careportal®, facilitate care and may further enable a single point of contact for patients from which clinicians may offer proactive interventions to optimize care.

A chromosomal analysis of Nepa cinerea Linnaeus, 1758 and Ranatra linearis (Linnaeus, 1758) (Heteroptera, Nepidae).

An account is given of the karyotypes and male meiosis of the Water Scorpion Nepa cinerea Linnaeus, 1758 and the Water Stick Insect Ranatra linearis (Linnaeus, 1758) (Heteroptera, Nepomorpha, Nepidae). A number of different approaches and techniques were tried: the employment of both male and female gonads and mid-guts as the sources of chromosomes, squash and air-drying methods for chromosome preparations, C-banding and fluorescence in situ hybridization (FISH) for chromosome study. We found that N. cinerea had a karyotype comprising 14 pairs of autosomes and a multiple sex chromosome system, which is X1X2X3X4Y (♂) / X1X1X2X2X3X3X4X4 (♀), whereas R. linearis had a karyotype comprising 19 pairs of autosomes and a multiple sex chromosome system X1X2X3X4Y (♂) / X1X1X2X2X3X3X4X4 (♀). In both N. cinerea and R. linearis, the autosomes formed chiasmate bivalents in spermatogenesis, and the sex chromosome univalents divided during the first meiotic division and segregated during the second one suggesting thus a post-reductional type of behaviour. These results confirm and amplify those of Steopoe (1925, 1927, 1931, 1932) but are inconsistent with those of other researchers. C-banding appeared helpful in pairing up the autosomes for karyotype assembly; however in R. linearis the chromosomes were much more uniform in size and general appearance than in N. cinerea. FISH for 18S ribosomal DNA (major rDNA) revealed hybridization signals on two of the five sex chromosomes in N. cinerea. In R. linearis, rDNA location was less obvious than in N. cinerea; however it is suggested to be similar. We have detected the presence of the canonical "insect" (TTAGG) n telomeric repeat in chromosomes of these species. This is the first application of C-banding and FISH in the family Nepidae.

Further studies on Boreonectes Angus, 2010, with a molecular phylogeny of the Palaearctic species of the genus.

Karyotypes are given for Boreonectes emmerichi (Falkenström, 1936) from its type locality at Kangding, China, and for B. alpestris (Dutton & Angus, 2007) from the St Gotthard and San Bernardino passes in the Swiss Alps. A phylogeny based on sequence data from a combination of mitochondrial and nuclear genes recovered western Palaearctic species of Boreonectes as monophyletic with strong support. Boreonectes emmerichi was placed as sister to the north American forms of B. griseostriatus (De Geer, 1774), although with low support. The diversity of Palaearctic species of the B. griseostriatus species group is discussed.

A remarkable new Helophorus species (Coleoptera, Helophoridae) from the Tibetan Plateau (China, Sichuan).

Helophorus dracomontanussp. n. is described from the Tibetan Plateau near Kangding, Sichuan, China. It is a member of the subgenus Helophorus s. str. but the anterolateral part of the pronotum resembles subgenus Gephelophorus Sharp, 1915. The short metallic-black maxillary palpi with almost symmetrical apical segments are suggestive of subgenus Kyphohelophorus Kuwert, 1886, but the elytral flanks are narrower than the epipleurs, excluding the species from that subgenus. An adjusted key to Helophorus s. str. is given to identify the new species, as well as H. jaechi Angus, 1995 and H. kozlovi Zaitsev, 1908.

Non-invasive ventilation for sleep-disordered breathing in Smith-Magenis syndrome.

Smith-Magenis syndrome (SMS) is a rare genetic neurodevelopmental disorder characterised by behavioural disturbances, intellectual disability and early onset obesity. The physical features of this syndrome are well characterised; however, behavioural features, such as sleep disturbance, are less well understood and difficult to manage. Sleep issues in SMS are likely due to a combination of disturbed melatonin cycle, facial anatomy and obesity-related ventilatory problems. Sleep disorders can be very distressing to patients and their families, as exemplified by our patient's experience, and can worsen behavioural issues as well as general health. This case demonstrates the successful use of non-invasive ventilation in treating underlying obesity hypoventilation syndrome and obstructive sleep apnoea. As a consequence of addressing abnormalities in sleep patterns, some behavioural problems improved.

A chromosomal analysis of eleven species of Gyrinidae (Coleoptera).

Karyotypes are presented for 10 species of Gyrinus Geoffroy, 1762: Gyrinus minutus Fabricius, 1798, Gyrinus caspius Ménétriés, 1832, Gyrinus paykulli Ochs, 1927, Gyrinus distinctus Aubé, 1836 var. fairmairei Régimbart, 1883, Gyrinus marinus Gyllenhal, 1808, Gyrinus natator (Linnaeus, 1758), Gyrinus opacus Sahlberg, 1819, Gyrinus substriatus Stephens, 1869, Gyrinus suffriani Scriba, 1855, Gyrinus urinator Illiger, 1807 and for Orectochilus villosus (Müller, 1776) (Coleoptera: Gyrinidae). The 10 Gyrinus species have karyotypes comprising 13 pairs of autosomes plus sex chromosomes which are X0 (♂), XX (♀), with the X chromosomes the longest in the nucleus. Orectochilus villosus has 16 pairs of autosomes plus X0, XX sex chromosomes. The data obtained by Saxod and Tetart (1967) and Tetart and Saxod (1968) for five of the Gyrinus species are compared with our results. Saxod and Tetart considered the X chromosome to be the smallest in the nucleus in all cases, and this is considered to result from confusion arising from uneven condensation of some of the chromosomes. Small differences between the chromosomes of different Gyrinus species have been detected, but not between Greenland and Swedish populations of Gyrinus opacus, nor between typical Gyrinus distinctus from France and Gyrinus distinctus var. fairmairei from Kuwait.

Resolving the taxonomic conundrum in Graphoderus of the east Palearctic with a key to all species (Coleoptera, Dytiscidae).

The Holarctic diving beetle genus Graphoderus (Dytiscinae, Aciliini) contains relatively few and well-known species but these may still be difficult to identify based on external characters. A taxonomic problem in the eastern Palearctic was discovered that relates to the Palearctic Graphoderus zonatus (Hoppe, 1795) and the Nearctic Graphoderus perplexus Sharp, 1882. Based on qualitative and quantitative characters, especially on male genitalia which have been poorly studied in the past, it is shown that eastern Palearctic specimens identified by previous authors as either of the two species in fact belongs to a third species. The synonymized name Graphoderus elatus Sharp, 1882, is reinstated as a valid species (stat. n.) and a lectotype is designated from the mixed syntype series. The male genitalia of all known Graphoderus species have been examined and an illustrated identification key to the genus is provided. The three species in the complex of focus, Graphoderus elatus, Graphoderus zonatus and Graphoderus perplexus are found to have allopatric distributions; Graphoderus perplexus in the Nearctic region, Graphoderus zonatus in the west Palearctic region and eastwards to the Yenisei-Angara river and Graphoderus elatus east of the Yenisei-Angara river. All previous records of either Graphoderus zonatus or Graphoderus perplexus in the east Palearctic, east of the Yenisei-Angara river turned out to be misidentified Graphoderus elatus. This conclusion also brings with it that dimorphic females, thought only to be present in the single subspecies Graphoderus zonatus verrucifer (CR Sahlberg, 1824), proved to be present also in a second species, Graphoderus elatus. The dimorphic female forms is either with dorsally smooth elytra and pronotum or conspicuously granulated elytra and wrinkly pronotum. As has been shown in Graphoderus zonatus verrucifer there is a correlation between the occurrence of granulate female forms in a population and an increase in the number of adhesive discs on pro- and mesotarsus in males within Graphoderus elatus.

Comparison of different cytogenetic methods and tissue suitability for the study of chromosomes in Cimex lectularius (Heteroptera, Cimicidae).

In the article we summarize the most common recent cytogenetic methods used in analysis of karyotypes in Heteroptera. We seek to show the pros and cons of the spreading method compared with the traditional squashing method. We discuss the suitability of gonad, midgut and embryo tissue in Cimex lectularius Linnaeus, 1758 chromosome research and production of figures of whole mitosis and meiosis, using the spreading method. The hotplate spreading technique has many advantages in comparison with the squashing technique. Chromosomal slides prepared from the testes tissue gave the best results, tissues of eggs and midgut epithelium are not suitable. Metaphase II is the only division phase in which sex chromosomes can be clearly distinguished. Chromosome number determination is easy during metaphase I and metaphase II. Spreading of gonad tissue is a suitable method for the cytogenetic analysis of holokinetic chromosomes of Cimex lectularius.

Further karyosystematic studies of the Boreonectesgriseostriatus (De Geer) group of sibling species (Coleoptera, Dytiscidae)-characterisation of B.emmerichi (Falkenström, 1936) and additional European data.

A lectotype is designated for the Tibetan species Deronectesemmerichi Falkenström, 1936 (Currently Boreonectesemmerichi (Falkenström)), and its habitus, as well as the median lobe and parameres of its aedeagus, are figured along with additional comparative material. Material of Boreonectesemmerichi from Sikkim (BMNH) represents the first record of a Boreonectes Angus, 2010 species from India. The karyotype of Boreonectesemmerichi is described as having 26 pairs of autosomes plus sex chromosomes which are X0 (♂), XX (♀). The karyotype is most like that of Boreonectesmacedonicus (Géuorguiev, 1959), but with slight differences. Additional chromosomal information is given for Boreonectesgriseostriatusgriseostriatus (De Geer, 1774) in the French Alps, Boreonectesgriseostriatusstrandi (Brinck, 1943) on the Kola Peninsula, Boreonectesmultilineatus (Falkenström, 1922) in the Pyrenees and Boreonectesibericus (Dutton & Angus, 2007) in the Spanish Picos de Europa.

Why don't they accept non-invasive ventilation?: insight into the interpersonal perspectives of patients with motor neurone disease.

OBJECTIVES: Although non-invasive ventilation (NIV) can benefit survival and quality of life, it is rejected by a substantial proportion of people with motor neurone disease (MND). The aim of this study was to understand why some MND patients decline or withdraw from NIV. METHOD: Nine patients with MND (male = 7, mean age = 67 years) participated in this study. These patients, from a cohort of 35 patients who were offered NIV treatment to support respiratory muscle weakness, did not participate in NIV treatment when it was clinically appropriate. Semi-structured interviews and interpretative phenomenological analysis (IPA) were employed to explore these patient's experience of MND and their thoughts and understanding of NIV treatment. RESULTS: Using IPA, four themes were identified: preservation of the self, negative perceptions of NIV, negative experience with health care services, and not needing NIV. Further analysis identified the fundamental issue to be the maintenance of perceived self, which was interpreted to consist of the sense of autonomy, dignity, and quality of life. CONCLUSIONS: The findings indicate psychological reasons for disengagement with NIV. The threat to the self, the sense of loss of control, and negative views of NIV resulting from anxiety were more important to these patients than prolonging life in its current form. These findings suggest the importance of understanding the psychological dimension involved in decision-making regarding uptake of NIV and a need for sensitive holistic evaluation if NIV is declined. Statement of contribution What is already known on this subject? Non-invasive ventilation is widely used as an effective symptomatic therapy in MND, yet about a third of patients decline the treatment. Psychological disturbance generated by NIV use leads to negative experiences of the treatment. Decision-making about treatment potentials is complex and unique to each individual affected by perceived impact of disease. What does this study add? A decision concerning NIV uptake was influenced by perceived impact on individuals' sense of self. Sense of self was influenced by the maintenance of autonomy, dignity, and quality of life. Individuals' sense of self was identified to have been challenged by the disease, NIV, and their experience of health care service.

The identity of Aphodius nodifrons Randall, 1838 (Coleoptera: Scarabaeidae: Aphodiinae) from Maine, United States of America, with designation of the lectotype and handwriting examples.

John Witt Randall's Coleoptera types have been assumed to be lost. In London and Harvard, we found two syntypes of Aphodius nodifrons Randall, 1838, coming from the collection of Thaddeus William Harris. We designated the lectotype and synonymised Randall's species with A. pedellus (De Geer, 1774).

Experience of long-term use of non-invasive ventilation in motor neuron disease: an interpretative phenomenological analysis.

OBJECTIVE: Although non-invasive ventilation (NIV) can promote quality of life in motor neuron disease (MND), previous studies have disregarded the impact of progression of illness. This study explored how patients' perceptions of NIV treatment evolve over time and how this was reflected in their adherence to NIV. METHODS: Five patients with MND (male=4, mean age=59 years), from a bigger cohort who were prospectively followed, had multiple post-NIV semistructured interviews, covering more than 12 months, along with ventilator interaction data. The transcribed phenomenological data were analysed using qualitative methodology. RESULTS: Three themes emerged: experience of NIV, influence on attitudes and perceived impact of NIV on prognosis. The ventilator interaction data identified regular use of NIV by four participants who each gave positive account of their experience of NIV treatment, and irregular use by one participant who at interview revealed a negative attitude to NIV treatment and in whom MND induced feelings of hopelessness. CONCLUSIONS: This exploratory study suggests that a positive coping style, adaptation and hope are key factors for psychological well-being and better adherence to NIV. More studies are needed to determine these relationships.

Karyotypes of some medium-sized Dytiscidae (Agabinae and Colymbetinae) (Coleoptera).

An account is given of the karyotypes of 29 species of medium sized Dytiscidae (Coleoptera). Of the 20 species of Agabus Leach, 1817, 18 have karyotypes comprising 21 pairs of autosomes and sex chromosomes which are either X0(♂) or XX (♀). These species are Agabus serricornis (Paykull, 1799), Agabus labiatus (Brahm, 1791), Agabus congener (Thunberg, 1794), Agabus lapponicus (Thomson, 1867), Agabus thomsoni (J. Sahlberg, 1871), Agabus confinis (Gyllenhal, 1808), Agabus sturmii (Gyllenhal, 1808), Agabus bipustulatus (Linnaeus, 1767), Agabus nevadensis Håkan Lindberg, 1939, Agabus wollastoni Sharp, 1882, Agabus melanarius Aubé, 1837, Agabus biguttatus (Olivier, 1795), Agabus binotatus Aubé, 1837, Agabus affinis (Paykull, 1798), Agabus unguicularis (Thomson, 1867), Agabus ramblae Millan & Ribera, 2001, Agabus conspersus (Marsham, 1802) and Agabus nebulosus (Forster, 1771). However two species, Agabus infuscatus Aubé, 1838 and Agabus adpressus Aubé, 1837, have developed a neo-XY system, with karyotypes comprising 21 pairs of autosomes and XY sex chromosomes (♂). No chromosomal differences have been detected between typical Agabus bipustulatus and Agabus bipustulatus var. solieri Aubé, 1837, nor have any been found between the three species of the Agabus bipustulatus complex (Agabus bipustulatus, Agabus nevadensis and Agabus wollastoni). The four species of Colymbetes Clairville, 1806, Colymbetes fuscus (Linnaeus, 1758), Colymbetes paykulli Erichson, 1837, Colymbetes piceus Klug, 1834 and Colymbetes striatus (Linnaeus, 1758) have karyotypes comprising 20 pairs of autosomes and sex chromosomes which are X0 (♂), XX (♀). Two of the species of Rhantus Dejean, 1833, Rhantus exsoletus (Forster, 1771) and Rhantus suturellus (Harris, 1828) have karyotypes comprising 20 pairs of autosomes and X0/XX sex chromosomes, but the other three species, Rhantus grapii (Gyllenhal, 1808), Rhantus frontalis (Marsham, 1802) and Rhantus suturalis (Macleay, 1825) have 22 pairs of autosomes and X0/XX sex chromosomes. Agabus congener and Rhantus suturellus may have one B-chromosome. Nine of the species have previously published karyotype data but for seven of these the data are wrong and are here corrected.