Latrodectus Species Research Articles

The first cytogenetic characterization of the poisonous black widow spider Latrodectus gr. curacaviensis from Brazil, with chromosomal review of the family Theridiidae (Arachnida, Araneae)

In this paper we present, for the first time, cytogenetical data on Latrodectus gr. curacaviensis (Theridiidae) from Brazil, as well as the first data on meiosis and sex chromosome system of this genus. Testes were submitted to colchicine, hypotonic, and fixation treatment, and chromosomal preparations were stained with Giemsa solution. The analysis showed 2 n = 26 telo/acrocentric chromosomes in spermatogonial metaphases. Metaphase I exhibited 12 autosomal bivalents and two sex chromosome univalents (12II + X 1X 2). All bivalents revealed one terminal chiasma. Metaphases II confirmed the sex chromosome system, showing 12 autosomes or 12 autosomes plus two X chromosomes, respectively. Male karyotype prevailing in theridiids is formed by 2 n = 22 chromosomes, including sex chromosome system X 1X 2 in all species. The Latrodectus species of the geometricus clade analyzed until now showed smaller diploid number (2 n♀ = 16 and 2 n♀ = 18) than the species of the mactans clade (2 n♀ = 24 and 2 n♀ = 26). Thus, according to the chromosome number, the examined Latrodectus species seems to be related to the mactans clade.

Toxic traveler? Latrodectus species envenomation in Michigan with refractory symptoms after antivenin administration

A 17-year-old male was envenomated on the right forearm by a black widow spider that had presumably traveled in a packaged dishwasher and been shipped from Mexico to Michigan. The patient experienced vomiting and severe pain in his abdomen and chest approximately 30 min after being bitten. He received 6000 units (1 vial) of Latrodectus antivenin intravenously about 7 h after he was envenomated. He did not experience significant improvement in his symptoms after the administration of antivenin and additional antivenin was not given. The patient was hospitalized for 7 days and still was complaining of intermittent episodes of pain in his chest and lower back 3 weeks after envenomation. To avoid prolonged symptomatology and hospitalization, additional Latrodectus antivenin should be given promptly to those individuals whose symptoms are not ameliorated after 1 vial.

Severe Reaction from Envenomation by the Brown Widow Spider, Latrodectus geometricus (Araneae: Theridiidae)

The brown widow, Latrodectus geometricus, is one of five species of Latrodectus in the United States, and is reported to be one of the least dangerous. However, we report a previously healthy patient bitten by a brown widow, resulting in a serious reaction requiring hospitalization. Symptoms included severe pain, cramps, nausea/vomiting, and fasciculations in the pectoral and quadriceps muscles. This report signals a need to re-evaluate previously held ideas that brown widow bites are of minor consequence.

MOLECULAR INSIGHTS INTO THE BIOGEOGRAPHY AND SPECIES STATUS OF NEW ZEALAND'S ENDEMIC LATRODECTUS SPIDER SPECIES; L. KATIPO AND L. ATRITUS (ARANEAE, THERIDIIDAE)

New Zealand's endemic sand dune Latrodectus widow spider species, L. katipo and L. atritus, possess behavioral and physiological attributes likely to promote dispersal over large distances. Morphological, physiological and behavioral similarities between L. katipo and L. hasselti, an Australian endemic, suggest gene flow may occur across the Tasman Sea. In this study we examine intraspecific and interspecific genetic relationships within the ND1 gene region between L. katipo, L. atritus, L. hasselti and L. hesperus to assess whether the genetic evidence supports current taxonomic species designations. We found low interspecific pairwise distances among L. katipo and L. atritus populations, suggesting either introgression, incomplete lineage sorting, or that the current taxonomic distinction between the two species may be invalid. Parsimony and maximum likelihood analyses were inconclusive as to the rela- tionships between the New Zealand Latrodectus species and the Australian L. hasselti. Low pairwise distances between L. hasselti and the New Zealand widow fauna indicated that L. katipo and L. atritus were not present in New Zealand before the fragmentation of Gondwana.

Morsures d’araignées : les aranéismes d’importance médicale

LIMITED RISKS: Although most species of spiders are venomous, only ten or so are able to induce human envenomations. From a systematic point of view, it is possible to distinguish the araneomorph spiders - or "true" spiders - from the mygalomorph spiders. Dangerous species for humans can be found in both groups. Regarding "true' spiders, two kinds of envenomation are frequent, ubiquitous and potentially severe: latrodectism (neurotoxic symptomatology) due to the Widow spiders of the Latrodectus species,and loxoscelism (viscero-cutaneous symptomatology). Regarding the mygalomorph spiders, the Australian species responsible for atraxism (neurotoxic symptomatology) are considered as the most dangerous. Most of the other mygalomorph spiders, when they bite, only provoke benign loco regional problems. A supplementary defensive weapon exists in certain South-American species: urticating hairs which may induce severe ocular damage.

ITS2 rDNA VARIATION OF TWO BLACK WIDOW SPECIES, LATRODECTUS MACTANS AND LATRODECTUS HESPERUS (ARANEAE, THERIDIIDAE)

Abstract The taxonomic status of two closely related species of Latrodectus, L. mactans and L. hesperus, has been debated for many years. Based on morphological characteristics and genitalia, some workers consider them as valid species and others as subspecies. This study was conducted to determine whether the internal transcribed spacers 2 (ITS2) of rDNA exhibit sequence differences between the two taxa that could delineate their taxonomic relationship. Individuals of L. mactans and L. hesperus from six populations were collected and identified based on morphological characteristics. The ITS2 rDNA of nine individuals was sequenced and analyzed. Results indicate that the minimal differences present in the ITS2 sequences are taxonomically insignificant.

The black widow spider genus Latrodectus (Araneae: Theridiidae): phylogeny, biogeography, and invasion history

The spider genus Latrodectus includes the widely known black widows, notorious because of the extreme potency of their neurotoxic venom. The genus has a worldwide distribution and comprises 30 currently recognized species, the phylogenetic relationships of which were previously unknown. Several members of the genus are synanthropic, and are increasingly being detected in new localities, an occurrence attributed to human mediated movement. In particular, the nearly cosmopolitan range of the brown widow, Latrodectus geometricus, is a suspected consequence of human transport. Although the taxonomy of the genus has been examined repeatedly, the recognition of taxa within Latrodectus has long been considered problematic due to the difficulty associated with identifying morphological features exhibiting discrete geographic boundaries. This paper presents, to our knowledge, the first phylogenetic hypothesis for the Latrodectus genus and is generated from DNA sequences of the mitochondrial gene cytochrome c oxidase subunit I. We recover two well-supported reciprocally monophyletic clades within the genus: (1) the geometricus clade, consisting of Latrodectus rhodesiensis from Africa, and its is sister species, the cosmopolitan L. geometricus, and (2) the mactans clade containing all other Latrodectus species sampled, including taxa occurring in Africa, the Middle East, Iberian Peninsula, Australia, New Zealand, and North and South America. Recovery of the geometricus and mactans clades is consistent with previous designations of species groups within the genus based on female genitalic morphology. All L. geometricus sampled, consisting of specimens from Africa, Argentina, North America, and Hawaii, were recovered as a strongly supported monophyletic group with minimal amounts of genetic divergence, corroborating the hypothesis that human transport has recently expanded the range of this species.

Toxic Spiders of the United States: A Case Report and Discussion

Although there are over 20,000 species of spiders in the United States serious complications from envenomation is restricted to only two genera: Loxoceles species (i.e., brown recluse type spiders) and Latrodectus species (i.e., black widow type spiders). Loxoceles species venom is primarily cyto/hemo toxic. It produces local necrotic lesions and occasionally systemic reactions including disseminated intravascular coagulation. Latrodectus species venom is primarily neurotoxic with little more than local erythema at the bite site, but with serious systemic effects from paresthesias to paralysis. A horse serum derived antivenin is available for Latrodectus envenomation while surgical intervention is often necessary for large necrotic lesions associated with Loxoceles envenomation.

我が国に分布する他 2 種のゴケグモ毒腺タンパク質に対するセアカゴケグモ抗毒血清の反応性

我が国に分布する他 2 種のゴケグモ毒腺タンパク質に対するセアカゴケグモ抗毒血清の反応性

The Stereotyped Behavior of Sexual Cannibalism in Latrodectus-Hasselti Thorell (Araneae, Theridiidae), the Australian Redback Spider

This paper presents the first account of stereotyped behaviour in the practice of sexual cannibalism in any species. Cannibalism is achieved by female Latrodectus hasselti spiders, primarily because the copulatory orientation of the male in this species is unique and does not conform to the orthodox posture of males of other Latrodectus species. In this case, after penetration of the epigynum with one palpal embolus, the male turns a somersault through 180-degrees so that his abdomen comes to rest against the female's mouthparts, whereupon she begins to devour him. The cannibalistic process is slow and the male often succeeds in a second intromission with the other palp. The somersault is highly stereo-typed and predictable; it was observed in all 56 intromissions in the present study. The nuptial death risk to the male during copulation if both palps are employed is 0.66. However, even if he escapes copulatory demise he will die from his injuries within two days. Male Latrodectus hasselti can be mated with female L. katipo, an allopatric species native to New Zealand. Somersaulting by the male L. hasselti also occurs in this inter-specific copulation but the female L. katipo makes no attempt to devour him. It is concluded that male somersaults and female cannibalistic behaviour in L. hasselti are genetically programmed events.

Black widow spider bites.

Black widow spiders (Latrodectus species) are found worldwide. Envenomation of humans usually occurs as the result of chance intrusion into the spider's domain by the human. The venom is regarded as one of the most potent biologic toxins. The venom acts by destabilization of cell membranes and degranulation of nerve terminals resulting in the release of neurotransmitters. The clinical picture is characterized by painful muscle spasm and hypertension. The very young, the elderly or enfeebled, and those with cardiovascular disease are at greatest risk. While not always necessary, the most effective treatment is specific antiserum. Muscle relaxants, analgesics and intravenous calcium are useful adjuvant treatment.

Revision of the Widow-spider genus Latrodectus (Araneae: Theridiidae) in Israel

The six species of Widow-spiders (Latrodectus) found in Israel are revised. Three of them are reported for the first time from this region. The Mediterranean L.tredecimguttatus is maintained as a distinct species differing from the American L.mactans, while evidence on the occurrence in Israel of a distinct population, close to the American L.hesperus is provided. Five sympatric species of Latrodectus are found in the more arid zones of Israel and one allopatric population of the cosmotropical L.geometricus occurs in the Mediterranean Coastal Plain. A conspectus on the systematics alongside distribution and ecological records of each species is given. The biological and morphological distinctive characters separating the species are then assessed in an extended discussion. Illustrations and a key to the species are provided.

A preliminary study of development in twoLatrodectusspecies (Araneae: Theridiidae)

Young spiders of two New Zealand Latrodectus species were reared to maturity. Considerable variability in growth rate, instar length, relative size, colouration, and patterning was observed both intraspecifically and interspecifically. In general, successive instars increased in length. In both species males matured in 4 moults and lived for only 4-10 weeks, whereas females matured in 6 moults and often lived for 2 years.

The Egg‐Sac in the Identification of Species of Latrodectus (Black‐Widow Spiders)

The Egg‐Sac in the Identification of Species of <i>Latrodectus</i> (Black‐Widow Spiders)

THE EMBRYOLOGY OF THE BLACK WIDOW SPIDER, LATRODECTUS MACTANS (FABR.)

The embryonic development of Latrodectus mactans, the black widow spider, from the time the egg is laid until the embryo is ready to emerge is described and an attempt made to correlate the internal developmental changes with changes in external body form. In agreement with observations of early students of spider embryology it is found that vitellocytes give rise to the mesenteron and hence the yolk cells are considered as the entoderm. The first blood cells are derived from extraembryonic cells, and are therefore ectodermal. A theory of head segmentation is suggested that contrasts with commonly accepted theories of arthropod segmentation by postulating that the spider brain is a syncerebrum made up of a protocerebrum, a greatly reduced tritocerebrum (= stomodaeal bridge), and cheliceral ganglia. The events in the development of the various systems in general closely parallel those described for many other species of spiders, but differ in some important respects from those described for another species of Latrodectus, namely Latrodectus hasselti Thorell.

Spiders of Genus Latrodectus

While several excellent reviews on arachnidism have been published in recent years (Bertin, 1950; Blair, 1934; Bogen, 1926; Greer, 1949; Machiavello, 1949) these have dealt primarily with the clinical problem of spider bite, and have given little information on classification of the poisonous spiders involved. Although differences in toxicity of venoms of various species of Latrodectus have been reported (Keegan, 1950; Shulov, 1948; Vellard, 1936) demonstrations, of common antigenic properties in venoms of L. mactans, L. indistinctus, and L. geometricus by Finlayson and Hollow (1945) indicates need for better understanding of the relationship between members of the genus. In this paper a brief review of the classification of spiders of genus Latrodectus is presented, and criteria for classification are discussed. This paper is based upon a study of the literature and upon examination of specimens from three sources. Specimens of L. hasseltii, L. geometricus, and the several described subspecies of L. mactans were made available by officials of the United States National Museum. Representatives of the same species, as well as L. tredecimguttatus and L. menavodi were obtained from the collections of the American Museum of Natural History through the courtesy of Dr. W. J. Gertsch. In the personal collection of the writer were specimens of L. hasseltii, L. geometricus, and L. mactans. Examples of L. hystrix, L. pallidus, L. indistinctus, L. revivensis, and L. foliatus were not available for study.