Nesticella mogera
(cave-dwelling spider)

Pictures

Identity

Preferred Scientific Name

• Nesticella mogera

Preferred Common Name

• cave-dwelling spider

Other Scientific Names

• Howaia mogera Lehtinen & Saaristo, 1980
• Nesticus mogera Yaginuma, 1972
• Nesticus terrestris Yaginuma, 1970

International Common Names

• English: cave cobweb spider; scaffold web spider

Summary of Invasiveness

This small web-building spider, a native of Japan, the Caucasus and the Far East, has only recently been introduced to Kauai in Hawaii, where it has replaced the endemic cave-dwelling spider, Erigone stygius.

It has also been introduced to some European countries, apparently via the tropical plants trade, and appears to be limited to tropical greenhouses, zoological gardens and garden centres where the conditions are warm and humid. 

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Arthropoda
•             Subphylum: Chelicerata
•                 Class: Arachnida
•                     Order: Araneae
•                         Family: Nesticidae
•                             Genus: Nesticella
•                                 Species: Nesticella mogera

Notes on Taxonomy and Nomenclature

The species name mogera is derived from the Japanese word for mole (mogura), since this species is commonly found in mole burrows in Japan (iNaturalist, 2016).

There is some confusion in the literature as to whether the genus Nesticella is a senior synonym of Howaia or whether these are two distinct genera (Marusik and Guseinov, 2003).

Description

Males have a body length up to 2.10 mm and females up to 2.63 mm (Nentwig et al., 2016).

The following description is adapted from Gertsch (1973).

The base colour of the carapace and appendages is dusky yellow, and the carapace has faint dark lines outlining pars cephalica and radiating from the cervical groove. The carapace has sparse hair covering, with usual erect bristles on the midline and ocular region. The sternum is dusky and legs are paler than the carapace and paler apically, without rings or makings, and with dusky femora. The abdomen is greyish and without pattern. Specimens from caves are whitish to pale yellow. The eye tubercles and the area inside the eyes is blackish.

The carapace is longer than it is wide and is evenly convex with a slight indication of cephalic grooves, and with a broad inconspicuous cervical groove. The pars cephalica is of medium height, highest just behind the eyes, and broadly rounded in front. Chelicera is typical, the promargin with 3 subequal teeth and the retromargin with a series of trivial denticles.

In females, the eye ratio, anterior lateral (ALE): anterior median (AME): posterior lateral (PLE): posterior median (PME), is 12:9:12:12. The front eye row is faintly procurved and anterior median eyes are separated by radius, half as far from the lateral eyes. The posterior eye row is weakly procurved, the median eyes are oval. 

In males, the eye ratio is 13:10:13:13. Eyes are closer together than in the female and the posterior row are clearly procurved with oval median eyes separated by a narrow radius.  

Female leg formula 1423. First leg 4.7 times, first femur 1.27 times as long as carapace. Third metatarsus 7/10 length of carapace. Tarsal comb with 8 toothed setae.

The Male leg formula 1423. First leg 4.8 X, first femur 1.3 X as long as carapace. Third metatarsus shorter than carapace. Legs proportionately longer but tarsal comb and claws like those of the female. The male pedipalps are typical of the genus, in that they possess a tarsal process bearing an asymmetrically T-shaped spur at the end.

Epigynum is small, subtriangular, with small median lobe projecting behind and dark tubules leading to small receptacles. 

Distribution

N. mogera was discovered in Japan, with a possible natural range in the Caucasus and the Far East, and it has been introduced to Hawaii (Kielhorn, 2009).

It is thought to have the widest distribution range of all nesticids (Marusik and Guseinov, 2003).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

N. mogera has been found in tropical greenhouses in Germany and the UK, possibly brought in with tropical plants (Kielhorn, 2009). It has also been found in Poland, thought to have been brought in due to intensive goods transportation and exchange (Rozwalka et al., 2013).

One specimen of N. mogera that was found in a garden centre in Lublin, Poland, is thought to have arrived with plants from the Netherlands, and so it is likely to be present there as well (Bielak-Bielecki and Rozwalka, 2011).

Introductions

Risk of Introduction

N. mogera has been introduced to some European countries, apparently via the tropical plants trade, and appears to be limited to tropical greenhouses, zoological gardens and garden centres where the conditions are warm and humid. Wherever similar routes in exist, there is the potential of the species being introduced to the wild if local conditions are favourable (Rozwalka et al., 2013).    

Habitat

N. mogera has been described as a cosmopolitan species that occurs in surface habitats and caves (Zhang and Li, 2013).

In Japan, N. mogera is found in leaf litter, the burrows of moles, and rarely in caves (Gertsch, 1973; Kielhorn, 2009). On the Hawaiian Island of Mauai, it is found in caves and in Fiji it has been found in bushes near a mangrove swamp and in jungle litter (Kielhorn, 2009). In South Korea it has been recorded in paddy fields, and ruderal vegetation in agricultural, industrial and residential areas (Kielhorn, 2009). In Azerbaijan it has been found in leaf litter on the edge of a relic forest (Rozwalka et al., 2013). In China it has been found in caves and under rocks near to caves (Zhang and Li, 2013).     

Rozwalka et al. (2013) describe its preferred habitat as in warm humid places, under stones and pieces of wood, and in thick forest litter and occasional caves. It is suggested that N. mogera may be a thermophilious and hygrophilious species, preferring a deep litter and places under stones (Bielak-Bielecki and Rozwalka, 2011).

Where spiders such as N. mogera have been introduced, they tend to occur more frequently inside buildings, on outside walls, in greenhouses and in warehouses etc. (Rozwalka et al., 2013).

Habitat List

Biology and Ecology

Genetics

Somatic cells of male and female Nesticus mogera [Nesticellamogera] have a chromosome number of 22 and 24, respectively (Wang and Wang, 1998). 

The genus Nesticella is polyphyletic, with several sub-clades and two clades distinctly separated from each other by the barrier of the Red River Fault in South China (Ballarin and Li, 2015). Analysis suggests that ancient colonisations followed by extinctions have occurred in the past (Ballarin and Li, 2015).

Reproductive Biology

N. mogera displays sexual dimorphism. The female is larger (Nentwig, 2016) and the male has specialised pedipalps (Gertsch, 1973).

Little information specific to reproduction in this species has been identified. However, as with other spiders, it is likely that the male locates the female via pheromones and deposits sperm onto a small web and then transfers this to the female genitalia using his pedipalps (Larsen, 2016). Usually, the eggs are fertilised by the sperm as they are laid a week or more after mating (Larsen, 2016).

The N. mogera female spins a round ball-like cocoon around her eggs once they are laid, and carries the cocoon with her (Spinnen Forum, 2015). Other members of the family Nesticidae carry the egg cocoon attached to their spinnerets, with the cocoon sometimes being larger than the female (Nieuwenhuys, 2010). Photographs available on Spinnen Forum (2015) suggest that this is the same in N. mogera.

Activity Patterns

Nesticus mogera [Nesticella mogera] in caves in Hawaii are described as spinning sloppy inverted webs between adjacent protuberances and in cracks in the walls (Howarth, 1978).

Nutrition

Like other spiders, it is assumed that N. mogera preys on small invertebrates.

Climate

Latitude/Altitude Ranges

Notes on Natural Enemies

It is assumed that N. mogera will be predated by other invertebrates, including other spiders, and by small mammals and birds. 

Means of Movement and Dispersal

Accidental Introduction

N. mogera has been accidentally introduced to garden centres, botanical gardens and zoos in Europe, presumably carried in on imported plant material (Rozwalka et al., 2013). As a result, there is a large population in the Butterfly House in Wroclaw Zoological Gardens, Poland (Rozwalka et al., 2013).

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

No information has been identified on the economic impact or the cost of any potential remedial measures taken to prevent impact by N. mogera. 

Environmental Impact

Impact on Biodiversity

N. mogera is recognised as responsible for replacing the native cave-dwelling spider Erigone stygius in caves in Kauai, Hawaii (Howarth, 1978; US Fish and Wildlife Service, 2006).  

Threatened Species

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Tolerant of shade
• Capable of securing and ingesting a wide range of food

• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species

• Competition - monopolizing resources

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field

Similarities to Other Species/Conditions

There are 29 species of Nesticella listed by ADW (2016) and the Encyclopedia of Life (2016).

Leg setae have been proposed as a diagnostic for the family Nesticidae (Grall and Jäger, 2016).

Phylogenetic analysis has suggested that there may be cryptic species currently defined as N. mogera (Zhang and Li, 2013).

Prevention and Control

No information on detection, prevention or control of N. mogera have been identified.

Gaps in Knowledge/Research Needs

There is a general lack of information on N. mogera. Information on most aspects of the life history of this species would be beneficial, especially if it has a negative impact on native species. 

More investigation on potential cryptic species currently assigned to N. mogera would also be beneficial.

Information on detection of this species and any potential methods of control is also sparse.

References

ADW, 2016. Animal Diversity Web. http://animaldiversity.org/accounts/Nesticella/classification/

Ballarin F; Li S, 2015. The uplift of Himalaya as a trigger for spider species diversification: the case of the genus Nesticella (Araneae: Nesticidae). 29th European Congress of Arachnology - Brno, Czech Republic, August. Brno, Czech Republic: Masaryk University and the Czech Arachnological Society, 208 pp. http://www.ta-service.cz/eca2015/files/ECA2015-Programme_Abstracts-31-08-2015.pdf

Bielak-Bielecki P; Rozwalka R, 2011. Nesticella mogera (Yaginuma, 1972) (Araneae: Nesticidae) in Poland. Acta Biologica, 18:137-141.

Encyclopedia of Life, 2016. Encyclopedia of Life. http://www.eol.org

Gertsch WJ, 1973. The cavernicolous fauna of Hawaiian lava tubes, 3. Araneae (spiders). Pacific Insects, 15(1):163-180.

Grall E; Jager P, 2016. Four new species of the spider genus Nesticella Lehtinen & Saaristo, 1980 from Laos, Thailand and Myanmar and the first description of the male of Nesticella yui Wunderlich & Song, 1995 with a proposed new diagnostic character for the family Nesticidae Simon, 1894 (Arachnida, Araneae). Zootaxa, 4085(2). http://www.mapress.com/j/zt/article/view/zootaxa.4085.2.5

Howarth FG, 1978. Proceedings of the second conference in natural sciences, Hawaii Volcanoes National Park [ed. by Smith, C. W.]. Hawaii, USA: University of Hawaii at Monoa, 350 pp. http://manoa.hawaii.edu/hpicesu/speci/2nd.pdf

iNaturalist, 2016. iNaturalist. California, USA: University of California Berkley. http://www.inaturalist.org/

Kielhorn K-H, 2009. First records of Spermophora kerinci, Nesticella mogera and Pseudanapis aloha on the European Mainland (Araneae: Pholcidae, Nesticidae, Anapidae). Arachnol. Mitt, 37:31-34. http://www.arages.de/aramit/pdf/Heft_37/AM37_31_34.pdf

Kim ST; Lee SY; Jung JK; Yoo JS; Lee JH, 2012. Spiders in Bangtaesan Mountain in Gangwon-do, Korea. Journal of Korean Nature, 5(1):1-9.

Larsen N, 2016. Spider reproduction, growth and development. Biodiversity Explorer. The web of life in Southern Africa. Cape Town, South Africa: Iziko. http://www.biodiversityexplorer.org/arachnids/spiders/reproduction

Marusik YM; Guseinov EF, 2003. Spiders (Arachnida: Aranei) of Azerbaijan. New family and genus records. Arthropoda Selecta, 12(1):29-46. http://caucasus-spiders.info/wp-content/uploads/2013/06/2003_MarusikGuseinovAzer.pdf

NatureServe, 2016. NatureServe Explorer: An online encyclopedia of life. Version 7. Arlington, Virginia, USA: NatureServe. http://explorer.natureserve.org/index.htm

Nentwig W; Blick T; Gloor D; Hanggi A; Kropf C, 2016. Spiders of Europe. Bern, Switzerland: Spiders of Europe. http://www.araneae.unibe.ch/#

Nieuwenhuys E, 2010. Cave cob spiders, Family Nesticidae. Amsterdam, Netherlands: Ed Nieuwenhuys. http://ednieuw.home.xs4all.nl/Spiders/Nesticidae/Nesticidae.htm

Pfliegler WP, 2014. Records of some rare and interesting spider (Araneae) species from anthropogenic habitats. , 7: 143-156. e-Acta Naturalia Pannonica, 7:143-156. http://epa.oszk.hu/01900/01957/00010/pdf/EPA01957_eactanat_2014_7_143-156.pdf

Rozwalka R; Rutkowski T; Bielak P, 2013. New data on introduced and rare synanthropic spider species (Arachnida: Araneae) in Poland. Biologia, 68(1):127-150.

Spinnen Forum, 2015. Spinnen Forum: Nesticella mogera. http://wiki.spinnen-forum.de/index.php?title=Nesticella_mogera

US Fish and Wildlife Service, 2006. Kauai Cave Amphipod, (Spelaeorchestia koloana). 5-Year Review. Honolulu, Hawaii, USA: Pacific Islands Fish and Wildlife Office. http://www.cabi.org/isc/FullTextPDF/2011/20117202595.pdf

Wang X; Wang J, 1998. On the karyotype of the Nesticus Mogera (Araneide: Nesticidae). Acta Arachnologica Sinica, 1988-01. http://en.cnki.com.cn/Article_en/CJFDTotal-ZXXB199801011.htm

Zhang Y; Li S, 2013. Ancient lineage, young troglobites: recent colonization of caves by Nesticella spiders. BMC Evolutionary Biology, 13:183.

Principal Source

Draft datasheet under review

Contributors

10/05/16 Original text by: 

Vicki Cottrell, Consultant, UK

Distribution Maps