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In late January 2017, Ms Eleanor Smith of Wilmslow (Cheshire, UK) visited the Manchester Museum and brought a medium-sized spider (see Fig. 1) that was found alive in a bunch of bananas, in a supermarket (Lidl) near Wilmslow. As she was told, the bananas on which the spider was found were delivered from Colombia. Unfortunately, the spider was already dead because Eleanor had kept the jar with the spider in a fridge; far too cold for such a tropical creature. The specimen was found to belong to what is commonly known as ‘Banana Spiders’. It was a mature female that was identified as Sadala sp. in the family Sparassidae, huntsman spiders. The specimen is now deposited in the Manchester Museum’s spider collection (accession number G7585.1).

Fig_01_Sparassidae_Colombia
Fig.1Female of Sadala sp. (Sparassidae) imported to the UK from Colombia; the Manchester Museum (G7585.1).

Spiders that are incidentally imported with bananas are commonly called ‘Banana Spiders’. However, this common English name is rather misleading, as it is used for quite a number of different spider groups.

In North America, this name can be applied to Golden Orb-web Spiders (Nephila species, family Nephilidae – most commonly Nephila clavipes); see also here and here. The reasons why this species is called ‘Banana Spider’ remain unclear, for there is no obvious connection between the spider and bananas – could it be because of the banana-shaped abdomen of rather large females? By the way, some Nephila species are edible and even considered a delicacy by indigenous people in New Caledonia and Australia, for instance, Nephila edulis (and here).

The wandering spiders (family Ctenidae) are regularly called ‘Banana Spiders’ as well (see Vetter et al., 2014). Some of them have even acquired a very bad media-reputation as deadly venomous species: for instance, the Brazilian Wandering Spider (Phoneutria fera). Alas, most of online media reports – for instance, MailOne(24 June 2015) or Independent(21 September 2016) – cannot be taken seriously, as they fail to even provide a correct identification of the spiders found on bananas.

In reality, to date, there has been only one published record of the Brazilian Wandering Spider as being imported to Europe (Germany) in 1950s, but yet the identification of that specimen causes doubts. The majority of existing records of “Brazilian Wandering Spiders”, both from Europe and from North America, are likely to belong either to the harmless Central American spider genus, Cupiennius (Ctenidae), or (much rarer!) to other Phoneutria species – most commonly, to Phoneutria boliviensis, a medically important wandering spider from Central America.

By far the most common spider group being imported with bananas is the pantropical huntsman spiders (family Sparassidae), also called ‘Banana Spiders’. In total, 13 species of huntsman spiders have been identified of those imported with bananas and other international goods to Europe. At least five species of huntsman spiders have been reported as being imported with bananas to the UK (Browning, 1954; Wilson, 2011): Barylestis occidentalis, Barylestis scutatus, Barylestis variatus (all from Africa), Heteropoda venatoria (from SE Asia, but now pantropical) and Olios sanctivincenti (from Asia). The commonest of them is Heteropoda venatoria, which is even established indoor in some regions of southern Europe (see Fig. 2). Yet, a real number of imported huntsman spiders might be much higher; Sadala sp. which was mentioned above (Fig. 1) is a new record from this group.

Fig_02_Heteropoda ventoria

Fig.2. Female (top) and male (bottom) of Heteropoda venatoria (Sparassidae);the Manchester Museum.

The spider collection of the Manchester Museum contains a number of samples of huntsman spiders collected from bananas in Manchester and its vicinities; for instance, from the Manchester Market Street in June 1912 or April 1931 (Fig. 3).

Fig_03_Banana Spiders

Several spider species that were obtained from the Manchester Open Air Market from imported bananas; the Manchester Museum.

Overall, a number of alien spider species that are imported with bananas and other international cargo to Europe or North America is rather high. For instance, Nentwig (2015) listed 184 species that have been imported to Europe over the last 200 years; of them 47 species have established there in and around human buildings. Vetter et al. (2014) identified 135 spider species imported to the USA in seven years (between 2006 and 2010). Although in the past banana or other fruit shipments were the main pathway of introduction to Europe, today potted plants and apparently container shipments in general are more important. It is suspected that due to the increasing international trade volume and climate change, in the next decades at least one new spider species will be introduced to Europe and established there annually.

Further reading

Nentwig W. (2015) Introduction, establishment rate, pathways and impact of spiders alien to Europe – Biol Invasions, 17: 2757–2778. DOI 10.1007/s10530-015-0912-5

Nentwig W. and Kobelt M. (2010) Spiders (Araneae). Chapter 7.3 – BioRisk, 4(1): 131–147. doi: 10.3897/biorisk.4.48

Vetter R.S., Crawford R.L., and Buckle D.J. (2014) spiders (Araneae) found in bananas and other international cargo submitted to North American arachnologists for identification – Journal of Medical Entomology, 51(6): 1136–1143. URL: http://www.bioone.org/doi/full/10.1603/ME14037

Wilson R. (2011) Some tropical spiders recorded in Leeds, West Yorkshire and a review of non-native taxa recorded in the UK – The Newsletters of the British Arachnological Society, No.120: 1–5.

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The Golden Orb-Weaving spider – Nephila clavipes (Linnaeus, 1767) of the family Nephilidae – is known from USA to Argentina. In Costa Rica, it occurs in lowland and premontane tropical rain forests. Females make large aerial webs in which they usually occupy the centre. Orb-web spiders are effective predators and can easily subdue prey that is significantly larger and heavier than the spider (see on photo).

Two females of Nephila clavipes with prey; Costa Rica.

Two females of Nephila clavipes with prey; Costa Rica.

One of the most peculiar characteristic of this species, as well as of other Nephila species, is an extreme sexual size dimorphism, where dwarf males can be many times smaller and lighter than the females (see on photo). Numerous hypotheses have been proposed to explain the factors that may give rise to such size dimorphism in spiders. Some of them are briefly discussed here.

In the case of Nephila, it is argued that that large size in females could be driven by selection on female fecundity (= the potential reproductive capacity), acting to increase the number of offspring produced. With the high level of juvenile mortality, the production of larger numbers of offspring is crucial for survival of the species. Thus such size dimorphism is almost always due to female gigantism rather than male dwarfism.

As was demonstrated for some African species [e.g., Nephila pilipes (Fabricius 1793)], females continue to grow after reaching maturity. The females mature at varying body sizes and instars and then continue to grow by molting the entire exoskeleton except their copulatory organs (=genitalia). Apparently, this is why in Costa Rica Nephila clavipes is represented by mature females of markedly variable body sizes (although, to date, a post-maturity molting has not been described for this species).

In a short video presented below (courtesy of Alex Villegas, Costa Rica) it is shown how a dwarf male of Nephila clavipes is approaching a giant female in its attempts to mate, alas unsuccessfully this tiem. Indeed, the male is to be careful in order not to be mixed up by the female with a potential prey.

Further reading:

Kuntner, M. & Coddington J.A. 2009. Discovery of the largest orbweaving spider species: the evolution of gigantism in Nephila. – Plos; DOI: 10.1371/journal.pone.0007516

Kuntner M., S. Zhang, M. Gregorič, and D. Li. 2012. Nephila female gigantism attained through post-maturity molting. – Journal of Arachnology 40(3):345-347. DOI: http://dx.doi.org/10.1636/B12-03.1

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On the second day of our field trip to Iceland, we visited the interesting site lying in the southern municipality of Reykjavik, called Garðabær, which literally means ‘Garden Town’. We walked around the beautiful Lake Urridavatn surrounded by boggy meadows full of sedge, dwarf bushes (like blue berry) and cotton grass (see on the photo).

Boggy meadow with cotton grass (left) and the blue berry bush (right) near Lake Urridavatn in Iceland

Boggy meadow with cotton grass (left) and the blue berry bush (right) near Lake Urridavatn in Iceland

On the meadow side of the path to the lake we found a plastic cup thrown by someone a few days ago. Incidentally, the cup, which was partly filled with rain water, became a deadly trap to insects and spiders. Having inspected the content of the cup I found two specimens of crab spiders (Xysticus sp.; male and female), one specimen of the ground beetle (family Carabidae) and one harvestman (family Phalangiidae). So, the cup ‘worked’ exactly in the way as true pitfall traps (see also here) that are used by scientists for ecological surveys. A poor thinking or maybe carelessness of someone who threw this plastic cup away instead of dropping it into a waste bin resulted in some casualties of minibeasts. Throwing a plastic cup (or any unwanted plastic item) away is hardly seen as a great deal or an action causing any threat to wild life. However, my short and simple story seems to say otherwise. In simple words, it reminds us that recycling waste is essential to both natural environment and humans, minimizing an unnecessary risk of damage to the environment and helping out our planet be a better place to live in. More about recycling can be seen here and here.

The plastic cup that became a deadly trap to a number of minibeasts near Lake Urridavatn in Iceland. See also a short video below.

The plastic cup that became a deadly trap to a number of minibeasts near Lake Urridavatn in Iceland. See also a short video below.

 

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Harvestmen (Opiliones) represent a diverse group of arachnids, with more than 6,500 species described worldwide; see here for a complete list. Everyone seems to be familiar with these animals which have an oval/round body and long-long thin legs; this why their English common name: ‘daddy-long-legs’. However, there are short-legged species as well. The harvestman fauna of the La Selva Natural Reserve (Costa Rica) consists of about 40 recorded species, half of which remain unnamed yet (Proud et al., 2012).

Image_01

A group of harvestmen (Prionoistemma sp.) on tree trunk, La Selva, Heredia, Costa Rica.

One of the interesting and commonest species of La Selva is Prionoistemma sp. (family Sclerosomatidae). This species has a small round pink body with black lateral spots and very long legs. Harvestmen usually spend the daytime on the trunk of large trees, at their bases, while during the night time they actively walk up and down the trunk and also over the undergrowth vegetation. When someone approaches them, the creatures begin to shake all over on their thin legs becoming almost invisible for a spectator.

The majority of harvestmen are omnivorous feeding on a variety diets, and seem to be effective predators. On the short video given below it is seen that this Prionoistemma male is feeding on a jumping spider (family Salticidae). The jumping spiders are very active and effective diurnal predators, with sharp colourful vision. Very few predators are capable of capturing them. How on the earth could this harvestman have seized the jumping spider remains a mystery. I’ve never observed this myself earlier.

Reference:

Proud D. et al., 2012. Diversity and habitat use of Neotropical harvestmen (Arachnida: Opiliones) in a Costa Rica rainforest. – ISRN Zoology, doi: 10.5402/2012/549765

 

 

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On the second day of our staying in San Jose (11th June), we had a chance to visit the Pre-Columbian Gold Museum (Museo del Oro) – the archaeological museum organized by the Central Bank of Costa Rica in 1950. This Museum hosts temporary exhibitions on a variety of themes and also houses a remarkable permanent gallery of pre-Columbian gold objects crafted between 300 A.D. and the 16th century, the time of the first contact with Europeans.

Objects manufactured during this period present a mixture of styles generated by contact and exchange with neighbouring regions such as modern central Panama and modern Colombia. Objects exhibited in the Museum were used as trade goods between regions and as ritual ornaments and funerary offerings. Many figures depict men with animal masks, apparently pointing to some superhuman qualities of those leaders who wore them. There are many animal figurines, including those of frogs, which are especially numerous, jaguar, alligators, bat, and others. Of the arthropods, only figurines of butterflies, crustaceans and spiders were displayed.

Pre-Columbian Gold Museum, San Jose, Costa Rica

Pre-Columbian Gold Museum, San Jose, Costa Rica

Butterflies
In traditional stories of the indigenous people of Talamanca, the butterfly is a woman who serves as an intermediary between the natural and supernatural worlds. This role of messenger and special being is reflected in the criteria used to select the woman who can be trained to carry out ritual tasks. They must have positive traits such as honesty, bravery and dedication.

Butterfly-shaped pendants, with the body representing alligators - the common practice of combining animals within a single object.

Butterfly-shaped pendants, with the body representing alligators – the common practice of combining animals within a single object.

Crustaceans
During the pre-Colombian period the marine environment was intensely exploited for edible species such as shrimps, crabs, lobsters and fish. Figurines of all these animals were manufactured as shown below.

Crab-shaped pendants.

Crab-shaped pendants.


Lobster-shaped pendants and circular pectoral (in the centre). The pectoral was a symbol of high rank among pre-Columbian people.

Lobster-shaped pendants and circular pectoral (in the centre). The pectoral was a symbol of high rank among pre-Columbian people.

Spiders
I could not photograph the autentic gold spider-shaped pendant in the Museum, and here is a photo of nice replica manufactured by a contemporary artists from the open-air market near the National Museum of San Jose.

Replica of the spider-shaped bell, with a hanging smaller bell.

Replica of the spider-shaped bell, with a hanging smaller bell.

The explanatory text provided above is based on the captions displayed in the Museo del Oro and the book by P. Esquivel (2012) ‘Extraordinary pieces from the Pre-Colombian Gold Museum’

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On June 10th, 2014, I visited the National Institute of Biodiversity in San Jose, Costa Rica (INBio, Instituto Nacional de Biodiversidad) and worked with the spider collections. The main aim was sorting out specimens of the jumping spider genus Lyssmanes (Salticidae) for its further taxonomic study. It is a collaborative project with the INBio’s arachnologist Carlos Viquez.

INBio is a private non-profit organization, founded in 1989, that works on the inventory of Costa Rican biodiversity. This institution carries out research on microorganisms, plants, insects and other animals. Since its foundation, INBio has discovered more than 2,700 species new to science. The institution retains large natural history collections numbering 4-5 million specimens and thousands of species. Here are a few photos resulted from my visit to INBio.

Cabinets with the spider collections, INBio, San Jose, Costa Rica

Cabinets with the spider collections, INBio, San Jose, Costa Rica

Carlos Viquez, the curator of the arachnid collections, INBio, San Jose, Costa Rica

Carlos Viquez, the curator of the arachnid collections, INBio, San Jose, Costa Rica

A drawer of fruit beetles from Costa Rica, INBio, San Jose, Costa Rica

A drawer of fruit beetles from Costa Rica, INBio, San Jose, Costa Rica

Slide collection of INBio, San Jose, Costa Rica

Slide collection of INBio, San Jose, Costa Rica

The large herbarium of INBio, San Jose, Costa Rica

The large herbarium of INBio, San Jose, Costa Rica

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Spider ID workshop at the Manchester Museum (Oxford Road, Manchester M13 9PL) on Saturday 2nd February, provisionally 10am – 4pm.

This workshop is for beginners and attendance at the workshop is free.

This course will introduce the common families of spider that can be found in the UK. Attendees will be shown basic spider anatomy and how to identify spiders to family level and also some easy spider species.

We will use microscopes and the recommended ID guides (provided, although some sharing may be necessary).

We may have some live spiders to examine, but the emphasis with the microscopes will be on how to identify preserved specimens in alcohol.

This is necessary to clearly understand the anatomy and features used in identification (which when familiarised can often be viewed with a hand lens on live spiders in the field).

Space is limited to 10 attendees.

Please contact Philip Baldwin, North West Regional Coordinator, to book your place on this workshop, preferably by email with your contact details; Mobile: 07585 606148, email philip.baldwin900@ntlworld.com; or Dmitri Logunov, the Curator of Arthropods (email: dmitri.v.logunov@manchester.ac.uk).

 Other events run by the British Arachnological Society can be checked upon online at: http://wiki.britishspiders.org.uk/index.php?title=Events,_etc.

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