Thomisus

Thomisus
Thomisus onustus capturing a bee
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Arachnida
Order:	Araneae
Suborder:	Araneomorphae
Section:	Dionycha
Superfamily:	Thomisoidea
Family:	Thomisidae
Tribe:	Misumenini
Genus:	Thomisus Walckenaer, 1805
Type species
Thomisus onustus Walckenaer, 1805
Species
T. kitamurai T. labefactus T. okinawensis T. onustus T. spectabilis many more, see text
Diversity
136 species

male Thomisus kitamurai from Japan

female Thomisus kitamurai

Thomisus is a genus of crab spiders (family Thomisidae) with more than 100 species described. The genus includes species that vary widely in their ecology, but the best known crab spiders are those species that people call the flower crab spiders, because they are ambush predators that feed on insects visiting flowers. The flower crab spiders are the species for which the popular name was coined, because of their crab-like motion and their way of holding their front legs in an attitude reminiscent of a crab spreading its claws as a threat.

Description and habits

As with most Thomisidae species, Thomisus exhibit sexual size dimorphism: females are four to ten mm in length, whereas males are only two to seven mm. Many are brightly colored, usually matching the color of the flower in which they are waiting in ambush.^[1] Not all species are flower-dwelling, but among those that are, at least some species can change their colour over a period of some days to match the flower colour.^[2] Studies suggest that bees are inclined to avoid a flower that contains a spider-sized object of a non-matching colour; whether this is specifically a mechanism for avoiding crab spiders, or simply that they are not attracted to flowers whose nectar guides are obscured however, is a more difficult question.^[3] The colour changes that such species can achieve are typically in ranges of white, pink, and yellow.

For example, in the Thomisus spectabilis species, the method of camouflage is similar to the Misumena vatia except the Thomisus spectabilis blend in with their environment while being visible to their prey, but not their predators. This species of crab spiders are UV reflective while the flower is UV absorbing creating a contrast between the spider and flower through the eyes of the pollinator.^[4] The contrast created greatly attracts pollinators such as honeybees. This evolutionary method of camouflage increased the likelihood the crab spiders encountered prey, which in turn effects the fitness of the crab spiders. Due to the increased encounter rate of prey the spiders are able to focus energy on reproduction therefore leading to increased fitness in the spiders. The evolutionary method of camouflage greatly increases the survivability and fitness of crab spiders.

Distribution

female Thomisus okinawensis

South African species of Thomisus in ambush on Lavandula, by a flower too small for her to occupy

South African species of Thomisus disturbed on Lavandula inflorescence

female T. labefactus

The distribution of Thomisus species is almost worldwide, with the notable exception of most of South America.^[5]The world spider catalog Although Thomisus species can be found almost anywhere on earth, most species occur in the tropics and the warmer regions of the Old World, with fewer species in the region from New Guinea to Australia and the New World. Only T. guadahyrensis is known from South America, and only in Peru.

Species

T. albens O. P.-Cambridge, 1885 — Pakistan, Yarkand T. albertianus Strand, 1913 — Gabon, Congo, Uganda, Angola T. albertianus guineensis Millot, 1942 — Guinea, Angola T. albertianus maculatus Comellini, 1959 — Cameroon, Congo T. albertianus verrucosus Comellini, 1957 — Congo T. albohirtus Simon, 1884 — North, East Africa, Yemen T. amadelphus Simon, 1909 — Vietnam T. andamanensis Tikader, 1980 — Andaman Islands T. angulatulus Roewer, 1951 — Gabon T. angustifrons Lucas, 1858 — Gabon T. arabicus Simon, 1882 — Yemen T. armillatus (Thorell, 1891) — Nicobar Islands T. ashishi Gajbe, 2005 — India T. australis Comellini, 1957 — Central, Southern Africa T. baghdeoi Gajbe, 2004 — India T. bargi Gajbe, 2004 — India T. beautifularis Basu, 1965 — India T. benoiti Comellini, 1959 — Congo T. bicolor Walckenaer, 1837 — USA T. bidentatus Kulczynski, 1901 — West Africa to Saudi Arabia, Yemen T. bigibbosus Keyserling, 1881 — USA T. blandus Karsch, 1880 — Africa, Yemen T. boesenbergi Lenz, 1891 — Madagascar T. bonnieri Simon, 1902 — Oman T. bueanus Strand, 1916 — Cameroon T. bulani Tikader, 1960 — India T. callidus (Thorell, 1890) — Sri Lanka, Singapore, Sumatra, Nias Islands, Java T. cancroides Eydoux & Souleyet, 1841 — Unknown T. candidus Blackwall, 1866 — Tropical Africa T. castaneiceps Simon, 1909 — Vietnam T. cavaleriei Schenkel, 1963 — China T. citrinellus Simon, 1875 — Mediterranean, Africa, Yemen, Socotra, Seychelles T. congoensis Comellini, 1957 — Central, Southern Africa T. dalmasi Lessert, 1919 — Africa T. danieli Gajbe, 2004 — India T. daradioides Simon, 1890 — South Africa to India T. daradioides nigroannulatus Caporiacco, 1947 — East Africa T. dartevellei Comellini, 1957 — Congo, Ethiopia, Malawi T. dentiger (Thorell, 1887) — Myanmar T. destefanii Caporiacco, 1941 — Ethiopia T. dhakuriensis Tikader, 1960 — India T. dhananjayi Gajbe, 2005 — India T. duriusculus (Thorell, 1877) — Sulawesi T. dyali Kumari & Mittal, 1997 — India T. elongatus Stoliczka, 1869 — India T. galeatus Simon, 1909 — Vietnam T. ghesquierei Lessert, 1943 — Congo T. godavariae Reddy & Patel, 1992 — India T. gouluensis Peng, Yin & Kim, 2000 — China T. granulatus Karsch, 1880 — Southern Africa T. granulifrons Simon, 1906 — India, Sri Lanka T. guadahyrensis Keyserling, 1880 — Peru T. guangxicus Song & Zhu, 1995 — China T. hararinus Caporiacco, 1947 — Ethiopia T. hui Song & Zhu, 1995 — China T. hunanensis Peng, Yin & Kim, 2000 — China T. ilocanus Barrion & Litsinger, 1995 — Philippines T. iswadus Barrion & Litsinger, 1995 — Philippines T. italongus Barrion & Litsinger, 1995 — Philippines T. janinae Comellini, 1957 — Congo, Tanzania T. jocquei Dippenaar-Schoeman, 1988 — Malawi T. kalaharinus Lawrence, 1936 — Africa, Yemen T. katrajghatus Tikader, 1963 — India T. keralae Biswas & Roy, 2005 — India T. kitamurai Nakatsudi, 1943 — Ryukyu Islands T. kiwuensis Strand, 1913 — Central Africa T. kokiwadai Gajbe, 2004 — India T. krishnae Reddy & Patel, 1992 — India T. labefactus Karsch, 1881 — China, Korea, Taiwan, Japan T. laglaizei Simon, 1877 — Myanmar, Philippines, Java, Sumatra T. lamperti Strand, 1907 — Madagascar

T. leucaspis Simon, 1906 — India, New Caledonia T. litoris Strand, 1913 — Central Africa T. lobosus Tikader, 1965 — India T. ludhianaensis Kumari & Mittal, 1997 — India T. machadoi Comellini, 1959 — Angola, Cape Verde Islands, South Africa T. madagascariensis Comellini, 1957 — Madagascar T. madagascariensis pallidus Comellini, 1957 — Madagascar T. manishae Gajbe, 2005 — India T. manjuae Gajbe, 2005 — India T. marginifrons Schenkel, 1963 — China T. meenae Gajbe, 2005 — India T. melanostethus Simon, 1909 — Vietnam T. mimae Sen & Basu, 1963 — India T. modestus Blackwall, 1870 — Italy T. natalensis Lawrence, 1942 — Southern Africa T. nepenthiphilus Fage, 1930 — Sumatra T. nirmali Saha & Raychaudhuri, 2007 — India T. nossibeensis Strand, 1907 — Madagascar T. obscuratus Caporiacco, 1947 — East Africa T. obtusesetulosus Roewer, 1961 — Senegal T. ochraceus Walckenaer, 1842 — Algeria T. odiosus O. P.-Cambridge, 1898 — Mexico T. okinawensis Strand, 1907 — Thailand to Ryukyu Islands, Philippines, Indonesia T. onustus Walckenaer, 1805 — Palearctic T. onustus meridionalis Strand, 1907 — North Africa T. oscitans Walckenaer, 1837 — USA T. pateli Gajbe, 2004 — India T. pathaki Gajbe, 2004 — India T. penicillatus Simon, 1909 — Vietnam T. perspicillatus (Thorell, 1890) — Borneo, Sulawesi T. pooneus Tikader, 1965 — India T. pritiae Gajbe, 2005 — India T. projectus Tikader, 1960 — India T. pugilis Stoliczka, 1869 — India T. purpuratus Walckenaer, 1837 — USA T. rajani Bhandari & Gajbe, 2001 — India T. retirugus Simon, 1909 — Vietnam T. rigoratus Simon, 1906 — India T. rishus Tikader, 1970 — India T. roeweri Comellini, 1957 — Tanzania T. schoutedeni Comellini, 1957 — Congo T. schultzei Simon, 1910 — Southern Africa T. scrupeus (Simon, 1886) — Africa T. shillongensis Sen, 1963 — India T. shivajiensis Tikader, 1965 — India T. sikkimensis Tikader, 1962 — India T. simoni Gajbe, 2004 — India T. socotrensis Dippenaar-Schoeman & van Harten, 2007 — Socotra T. sorajaii Basu, 1963 — India T. spectabilis Doleschall, 1859 — India to Australia T. spiculosus Pocock, 1901 — West, Central, Southern Africa T. stenningi Pocock, 1900 — Africa, Yemen T. stigmatisatus Walckenaer, 1837 — USA T. stoliczkai (Thorell, 1887) — Myanmar T. sundari Gajbe & Gajbe, 2001 — India T. swatowensis Strand, 1907 — China T. tetricus Simon, 1890 — Yemen T. transversus Fox, 1937 — China T. trigonus Giebel, 1869 — Germany T. tripunctatus Lucas, 1858 — West Africa T. tuberculatus Dyal, 1935 — Pakistan T. turgidus Walckenaer, 1837 — USA T. unidentatus Dippenaar-Schoeman & van Harten, 2007 — Yemen T. venulatus Walckenaer, 1842 — Algeria T. viveki Gajbe, 2004 — India T. vulnerabilis Mello-Leitão, 1929 — Myanmar T. whitakeri Gajbe, 2004 — India T. yemensis Dippenaar-Schoeman & van Harten, 2007 — Yemen T. zhui Tang & Song, 1988 — China T. zuluanus Lawrence, 1942 — South Africa T. zyuzini Marusik & Logunov, 1990 — Saudi Arabia to Central Asia

References

1. Murphy, Frances & Murphy, John (2000). An Introduction to the Spiders of South-East Asia. City: Malaysian Nature Society. ISBN 983-9681-17-6.
2. Filmer, Martin (1997). Southern African Spiders. City: BHB International / Struik. ISBN 1-86825-188-8.
3. Reuven Dukas and Douglass H. Morse ; Crab spiders affect flower visitation by bees ; OIKOS 101: 157–163, 2003
4. Gawryszewski, F. M., A. L. Llandres, and M. E. Herberstein. "Relationship between colouration and body condition in a crab spider that lures pollinators." Journal of Experimental Biology 215, no. 7 (2012): 1128-1136.
5. Platnick, Norman I. (2008): The world spider catalog, version 8.5. American Museum of Natural History.

Supplementary reading

• Murphy, Frances & Murphy, John (2000): An Introduction to the Spiders of South East Asia. Malaysian Nature Society, Kuala Lumpur.
• Platnick, Norman I. (2008): The world spider catalog, version 8.5. American Museum of Natural History.