Rhopalurus laticauda factsheet

  • Rhopalurus laticauda
    (Thorell, 1876)


    What’s in a name?
    R. laticauda has no generally accepted common name. Rhopalurus males all have distally widened metasoma, hence their genus name, which translated from Greek means literally “club like tail” (Rhopalos = club, uros
    =tail). Also, laticauda (cauda = tail in Latin) means basically the same, wide or broad tail.


    Distribution
    The Llanos of Colombia and Venezuela (see Discussion below).


    Natural habitat
    This species does not dig burrows, but it hides under stones, surface debris, logs and such. It is capable of digging small scrapes under these objects. Venezuela has a predominantly tropical hot and humid climate, where savanna and rainforests predominate. This species inhabits deciduous forests and semi-arid regions, like savannahs (also in Colombia). These have sandy soils and are covered with spiny bushes, grasses and clusters of trees. The dry season is from November through May, but there are regional climatic differences. Some parts of the coastal areas may not receive any rain for up to ten months, while the southern parts (Amazonas) do not really have a dry season. The average day temperature is 27° C (81° F). This species readily enters houses and buildings in some areas in Venezuela.

    Venom
    Although this scorpion is from the family Buthidae Koch, 1837, it is not considered medically important. The LD50 value of the venom is low, 30 mg/ kg. Because it is rather common in some areas, this species is responsible for a relative large number of stings. The majority of the cases of envenomations result in local pain and/ or mild swelling or redness of the sting site.


    Morphological information
    This is a small to medium-sized scorpion (total length 45-70 mm). Size variation is not uncommon in Rhopalurus (and other Buthids for that matter). The base color is yellowish to light brown. Fingers of the pedipalp are darker as the chela. Metasomal segments I-III yellowish to light brown, segment IV reddish brown and segment V dark brown to black. There is a dark stripe on the ventral side of the metasoma. Vesicle reddish brown to dark brown.
    Tergites have one median keel. Compared to females, males are somewhat smaller and have less robust mesosoma’s, but more bulbous chela and metasoma, and the pedipalp fingers are scalloped so a basal gap is evident when closed. The vesicle is small and has a short, curved aculeus. The subaculear tooth is absent or small, shaped as a blunt to spinoid granule. Pectinal tooth counts overlap between sexes, 23-26 in males, 20-25 females. There are eight rows of granules on both fingers.
    This species stridulates through brushing of the pectines against the sternites. The pectines have special structures called lyriform files. These somewhat resemble the lamellae on the ventral side of the feet of some geckoes. Stridulation is probably used to warn potential predators, because they do not stridulate during foraging or mating.

    Keeping in captivity
    The latter of the following information is based on my own experience and the information given below is an example of how you can keep this species. Because this species is not yet commonly kept, good information about the ideal captive conditions is not readily available.I keep R. laticauda warm and dry. I keep the temperature between 25-30° C (77-86° F) in the daytime and around 20° C (68° F) during the night. I use a mixture of dry humus and sand as substrate, on which some flat stones and pieces of cork bark are placed for the scorpions to hide under. The substrate layer is a bit more then 2.5 cm (one inch) thick, since they do not burrow. Regarding the relative humidity, it seems that young are more prone to dehydrate then their adult counterparts. To prevent fungal infections one must be careful not to keep this species too moist and enclosures must be well ventilated.
    To maintain a proper humidity level, one needs to spray some water in a corner of the enclosure. I spray the adult's enclosures once a month and the instars' enclosures once or twice a week. A small bottle cap of fresh water is provided weekly for adults, the young drink from the droplets of water after spraying. Instars can be kept in wider deli cups. The young can be raised on small (pinhead) crickets after they have left their mother, smaller food like fruit flies, is not necessary. Adults feed on larger crickets. Young are best raised separately to avoid cannibalism. There is much unknown about the postembryonic development of this species. One female in my care gave birth to 26 young, after an estimated gestation period of about 5-7 months. It took 9 days for the young to molt to instar 2. They left their mothers’ dorsum after 14 days. Life expectancy in captivity is around 3 years. Rhopalurus spp. do not produce multiple broods from a single insemination, thus it needs to mate again after giving birth.


    FAQ
    1. Q: What’s the difference between R.laticauda and R.junceus?
    A: R.laticauda is much smaller. An adult R.laticauda measures around 45-70 mm and an adult
    R.junceus from 10-125 mm. R.laticauda has a different overall coloration (more yellow).
    2. Q: My male doesn’t eat regularly, is it sick?
    A: In general males, are not as ‘good’ eaters as females. Sometimes they take longer before they
    catch their prey. Sometimes they even get stressed by overactive crickets. Remove the cricket
    when it is not eaten in 48 hours and try again the next week. In general you can feed instars twice
    a week and adults once a week.
    3. Q: My scorpion died a week after molting/ suddenly died/ was stuck in a molt, but I kept the
    temperature and humidity exactly as described above?
    A: This happens sometimes. Scorpions die sometimes even if you are keeping them under the right
    captive conditions and if there are not (obvious) external indications of sickness.
    4. Q: My R..laticauda is rather docile and rarely reacts agressive, can I handle it?
    A: I do not recommend handling any scorpion with your bare hands.
    5. Q: How can I tell the difference between a male and a female?
    A: The males have posteriorly widened metasomal segments, more bulbous chela and are somewhat
    thinner and smaller than the females. There is a “gap” between the tibial and moveable finger of
    the pedipalp in males. Females are more plump and larger.
    6. Q: What does “deciduous forests” mean?
    A: This means that the vegetation looses its leaves after the growing season to preserve water. In the
    tropics this happens before the beginning of the dry season.

    Discussion
    The genus Rhopalurus currently consists of 17 species, R. laticauda is the type species of the genus and was discovered first in Colombia, but according to the literature (see references) it occurs in Brazil (Roraima, Amazonas), Colombia, Guyana and Venezuela.
    This species used to be divided into two subspecies: Rhopalurus laticauda laticauda Thorell, 1876 (Colombia, Venezuela) and Rhopalurus laticauda pintoi Mello-Leitão, 1932 (Brazil and Guyana). The Brazilian records where derived from Lourenço’s 1982 revision of the genus, where both R. crassicauda and R. pintoi were synonymized under R. laticauda as R. laticauda pintoi. Later, the Brazilian records where regarded as erroneous by the same author (Lourenço, 2002) when he restored back R. crassicauda, and Teruel (2006) resurrected R. pintoi.
    Not all the facts are yet known about the distribution of R. laticauda and it’s (relation to) closely related species. Most of the literature refers to R. laticauda and not all of the records where confirmed. It is not yet fully understood how to interpret intraspecific variation between the specimens that where collected from different areas. More specimens from Venezuela and Guyana should be studied to gain a better understanding about these subjects. R. laticauda is closely related to both R. crassicauda Caporiacco, 1947 and R. caribensis Teruel & Roncallo, 2008; R. crassicauda is smaller and lacks a spinoid subaculear tooth, and R. caribensis has a bright yellow coloration and does not have a totally darkened metasomal segment V.


    digital images: 1. female with instar 1, 2. adult male, 3. adult female


    Acknowledgements
    Many thanks to Rolando Teruel for sharing valuable information and for reviewing this factsheet, and to Wilson R. Lourenço, for information and advice.


    References


    FET, V. & G. LOWE. 2000. Family Buthidae. Pp. 54-286. In: Catalog of the Scorpions of the World (1758-1998) (eds. V. Fet, W. D. Sissom, G. Lowe & M. E. Braunwalder). New York Entomological Society, 690 pp.


    GONZÁLEZ-SPONGA, M. A. 1996. Guía para identificar los escorpiones de Venezuela. Cuadernos Lagoven, Caracas, 204 pp.


    LENARDUCCI, A. R. I. P., R. PINTO DA ROCHA & S. M. LUCAS. 2005. Descrição de uma nova espècie de Rhopalurus Thorell, 1876 (Scorpiones: Buthidae) do nordeste brasileiro. Biota Neotropica, 5(1a): 1–8.


    LOURENÇO, W. R. 2002. Scorpions of Brazil. Les Éditions de l’If, Paris, 307 pp.


    LOURENÇO, W., D. HUBER & J. L. CLOUDSLEY-THOMPSON. 2000. Description of the stridulatory apparatus in some species of the genus Rhopalurus Thorell (Scorpiones: Buthidae). Ekológia, Bratislava, 19(3): 141-144.


    SOUSA, L. DE, P. PARRILLA-ALVAREZ & M. QUIROGA. 2000. An epidemiological review of scorpion stings in Venezuela: the Northeastern region. Journal of Venomous Animals and Toxins, 6(2).


    TERUEL, R. 2006. Apuntes sobre la taxonomía y biogeografía del género Rhopalurus Thorell 1876 (Scorpiones: Buthidae), con la descripción de dos nuevas especies de Cuba. Boletín de la Sociedad Entomológica Aragonesa, 38: 43-54.


    TERUEL, R. & C. A. RONCALLO. 2008. Rare or poorly known scorpions from Colombia. III. On the taxonomy and distribution of Rhopalurus laticauda Thorell, 1876 (Scorpiones: Buthidae), with description of a new species of the genus. Euscorpius, 68: 1-12.


    M.A.C.Cozijn © 2008. All text and digital images are my property. If you want to use information or pictures, please contact me through PM.