Abnormal morphology of an adult Rocky Mountain wood tick, Dermacentor andersoni (Acari: Ixodidae)

Hard ticks in Burmese amber with Australasian affinities

Three examples of metastriate hard ticks (Ixodida: Ixodidae) with apparent affinities to modern Australasian genera are described from the mid-Cretaceous (ca. 100 Ma) Burmese amber of Myanmar. Two nymphs of Bothriocroton muelleri sp. nov. represent the oldest (and only) fossil record of this genus, living members of which are restricted to Australia and predominantly feed on monitor lizards, snakes and echidnas. A female of Archaeocroton kaufmani sp. nov. shares its basis capitulum shape with the tuatara tick Archaeocroton sphenodonti (Dumbleton, 1943), the only extant member of this genus and an endemic species for New Zealand. The presence of 2 Australasian genera in Burmese amber is consistent with a previous record of an Ixodes Latreille, 1795 tick from this deposit which resembles Australian members of this genus. They further support an emerging hypothesis that fauna of the amber forest, which may have been on an island at the time of deposition, was at least partly Gondwanan in origin. A revised evolutionary tree for Ixodida is presented compiling data from several new Burmese amber ticks described in the last few years.

Morphological abnormalities in Hyalomma dromedarii and Hyalomma rufipes (Acari: Ixodidae) collected from dromedary camels (Camelus dromedarius) in Aswan, Egypt

The present study reports anomalies in Hyalomma dromedarii and Hyalomma rufipes adults collected from dromedary camels (Camelus dromedarius) in Aswan, Egypt, between January and June 2022. A total of 52 adult ticks displayed one or several local and/or general anomalies. A wide variety of local anomalies was observed including atrophy of one or multiple legs, ectromely, absence of accessory adanal and subanal plates, fusion of adanal and accessory plates, and presence of sclerotized formation in the ventral plate, as well as abnormalities of the spiracle, anal groove, festoon, parma, and posteromedian groove. General anomalies comprised of asymmetries and gynandromorphism. Local anomalies were documented among H. dromedarii and H. rufipes, whereas general anomalies were documented only from H. dromedarii. The present work represents the first report of deuterogynander intrigue gynandromorphism in H. dromedarii, as well as the first report of morphological abnormalities in H. dromedarii and H. rufipes from Egypt.

Morphological abnormalities and multiple mitochondrial clades of Rhipicephalus haemaphysaloides (Ixodida: Ixodidae)

Rhipicephalus haemaphysaloides is endemic in South and Southeast Asia, and it is known to parasitise domestic animals such as cattle, horses, sheep, and dogs. Despite infestation on multiple hosts, little attention has been paid to its morphological and molecular variation. The present study describes local morphological abnormalities for the first time in R. haemaphysaloides from Malaysia, and highlights the presence of three cytochrome c oxidase subunit I (COI) operational taxonomic units with 0.46-9.81% distances within the so-called R. haemaphysaloides in Malaysia, Thailand, and Pakistan.

Morphological anomalies in Rhipicephalus sanguineus s.s. (Acari: Ixodidae) collected from dogs in steppe and high plateaus regions, Algeria

The present report describes morphological anomalies in Rhipicephalus sanguineus s.s. collected from dogs between February 2017 and May 2019 in the steppic region of Djelfa and high plateau area of Bordj-Bou-Arreridj in Algeria. Out of 1043 ticks from 147 infested dogs, four adult ticks (0.38%), collected from four dogs, exhibited local morphological abnormalities. One male displayed ectromely of leg I left, and the other three specimens exhibited multiple associated anomalies in idiosomas and exoskeletons, festoons, stigmas (spiracles), as well as in adanal and accessory plates. This report provides additional exemplars of morphological abnormalities in tick populations of Africa, particularly North Africa.

Morphological abnormalities in ticks (Acari: Ixodidae) collected from domestic animal species in Sudan

Morphological abnormalities in ticks have rarely been reported in nature. The existing knowledge about anomalies in ticks collected in Africa is very sparse. In this paper, we describe abnormalities in Amblyomma, Hyalomma, and Rhipicephalus ticks collected from cattle, sheep, goats, camels, and horses in Kassala and North Kordofan states, Sudan, between January and August 2017. A number of 15 adult ticks displayed one or several local anomalies, such as ectromely, abnormalities of the ventral plates, and body deformities, besides newly described multiple cuticula scars. This study presents the first report of local anomalies in ticks belonging to three genera in Sudan and highlights the need to investigate the association between such morphological abnormalities and tick biology.

A case of morphological anomalies in Amblyomma americanum (Acari: Ixodidae) collected from nature

We describe a case of morphological anomalies in Amblyomma americanum, a medically important species associated with several human diseases and medical conditions. Based on morphological characters using dichotomous morphological keys, high-resolution light microscopy, and scanning electron microscopy imaging, the tick was identified as Am. americanum nymph exhibiting various morphological anomalies including ectromely associate with asymmetry, olygomely (lack) of the fourth left leg, and schizomely (bifurcation of palpus) on the right side. We believe this is the first report of the presence of several spontaneous anomalies in one Am. americanum specimen. Morphological identity of the specimen was corroborated by DNA sequencing of the mitochondrial 16S region. We discuss recent reports of morphological anomalies in ixodid ticks and emphasize the significance of additional studies of teratology in medically important tick species and its potential implications.

A seven-legged tick: Report of a morphological anomaly in Ixodes scapularis (Acari: Ixodidae) biting a human host from the Northeastern United States

Cases of morphological anomalies in the blacklegged tick, Ixodes scapularis (Acari: Ixodidae), have recently been reported from the Northeastern and upper Midwestern United States, potentially complicating identification of this important vector of human disease-causing pathogens. We hereby report a case of a morphological anomaly in I. scapularis, biting a human host residing in Norwich, Connecticut. Using a dichotomous morphological key, high-resolution and scanning electron microscopy images, as well as DNA sequencing, the tick was identified as an adult female I. scapularis with three legs on the left side of the abdomen versus four on the right side, which we believe is the first case of ectromely in an adult I. scapularis. Using diagnostic genes in polymerase chain reaction, the specimen tested positive for Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum, the causative agents for Lyme disease and anaplasmosis, respectively, and also showed evidence of a rickettsial endosymbiont. Here we discuss recent reports of morphological anomalies in I. scapularis, and emphasize the significance of additional studies of teratology in this important tick species and its potential implications.

Abnormal Development of Hyalomma Marginatum Ticks (Acari: Ixodidae) Induced by Plant Cytotoxic Substances

The increasing application of toxic plant substances to deter and fight ticks proves the need for investigations focused on the elucidation of their impact on the developmental stages and populations of these arthropods. We examined the course of embryogenesis and egg hatch in Hyalomma marginatum ticks under the effect of cytotoxic plant substances. The investigations demonstrated that the length of embryonic development of egg batches treated with 20 μL of a 0.1875% colchicine solution did not differ significantly from that in the control group. Colchicine caused the high mortality of eggs (16.3%) and embryos (9.7%), disturbances in larval hatch (8.1%), and lower numbers of normal larval hatches (65.6%). In 0.2% of the larvae, colchicine induced anomalies in the idiosoma (67.6%) and gnathosoma (22.5%) as well as composite anomalies (8.5%). The study demonstrates that cytotoxic compounds with an effect similar to that of colchicine can reduce tick populations and cause teratological changes, which were observed in the specimens found during field studies. Since there are no data on the toxic effects of active plant substances on other organisms and the risk of development of tick resistance, a strategy for the use of such compounds in tick control and the management of plant products should be developed.

General and Local Morphological Anomalies in Amblyomma lepidum (Acari: Ixodidae) and Rhipicephalus decoloratus Infesting Cattle in Uganda

Morphological abnormalities in ticks seem to be rare phenomena in nature, and are underreported in Africa. In this article, we describe general and local anomalies in two Amblyomma lepidum females and one Rhipicephalus decoloratus female collected from cattle in Moroto and Kasese districts, Uganda. One A. lepidum specimen displayed metagynander gynandromorphism with the presence of both male and female features in the same organism. The second A. lepidum female showed slight asymmetry and lacked a genital aperture. The R. decoloratus displayed multiple anomalies that included asymmetry on the right side in association with ectromely, chitinous formations and constrictions on the left side. This article presents the first report of metagynander gynandromorphism, as well as genital aperture absence which is not linked to gynandromorphism, in A. lepidum collected from cattle.

Morphological anomalies in Ixodes ricinus and Ixodes inopinatus collected from tick-borne encephalitis natural foci in Central Europe

In 2015, 0.02% nymphs displayed anomalies (ectromely) out of the 6744 collected ticks as part of a tick-borne encephalitis program in Germany. In 2016, questing Ixodes ricinus (n = 14,527) and Ixodes inopinatus (n = 75) ticks were collected by flagging as part of a tick-borne encephalitis program in Germany, Slovakia and Denmark. A total of 278 (1.9%) out of 14,602 nymph and adult ticks showed morphological anomalies. The anomalies were divided into general anomalies (body asymmetry) and local anomalies (anomalies of appendages, malformation of capitulum, exoskeleton anomalies and anal groove deformation) with nymphs being the most affected life stage. Most important, leg atrophy was the most common anomaly (209 nymphs, 11 females and three males) followed by asymmetry (10 nymphs, five females and a male) and ectromely (nine nymphs). Two females and one male displayed multiple anomalies on legs, palps and exoskeleton. Anal groove deformation was observed in three females and three nymphs. In 2016, the frequency of anomalies in I. inopinatus was found five times higher (9.3%) than in I. ricinus (1.9%). This is the first report of anomaly (ectromely, leg atrophy, idiosoma deformation) in flagged I. inopinatus and the first report of schizomely in I. ricinus.

Abnormal Development of Haemaphysalis qinghaiensis (Acari: Ixodidae)

A single Haemaphysalis qinghaiensis specimen exhibiting abnormal morphology was collected from a tick laboratory colony. The tick had a heart-shaped body with partial twinning of the posterior region (with two anal orifices and two genital grooves). To the best of our knowledge, this is the first report of teratological changes in H. qinghaiensis The abnormal morphological features are described herein.

External morphological anomalies in ixodid ticks from Thrace, Turkey

Of 18,667 ticks examined, 33 specimens from species identified as Haemaphysalis parva, Hyalomma marginatum, Hy. scupense, Rhipicephalus bursa and Rh. turanicus were found to have external morphological anomalies. Anomalous Ha. parva, Hy. scupence and Rh. turanicus were reported in this study for the first time. General anomalies manifested as asymmetry and deformations of the idiosoma, whereas local anomalies occurred in legs, exoskeleton, spiracular, adanal, subanal and accessory plates, mouthparts and capitulum. With this study describing a gynandromorphic Hy. marginatum, the number of gynandromorphic tick cases has been raised to two in Turkey.

Morphological Characteristics of Normal and Gynandromorphic Hyalomma asiaticum Schulze and Schlottke, 1930

Gynandromorphic ticks are extremely rare, and often attract parasitologists’ attention. During our examination of tick specimens, an engorged gynandromorph of Hyalomma asiaticum was noticed. This is the first record of gynandromorphic ticks from China. In this study, several important morphological structures of normal and gynandromorphic H. asiaticum were analyzed. Comparing to the normal H. asiaticum, the gynandromorphic specimen was a typical bipartite protogynander. Its right side showed normal female characteristics, whereas the left side had normal male traits. Different from other gynandromorphic ticks containing 1 anus, this tick reported here had 2 complete anuses, and the anus of the male part had a single adanal plate.