Bipalium kewense

File:Bipalium kewense head.jpg

Bipalium kewense is a very long land planarian. Preserved specimens are up to 20 centimetres in length, and living specimens may be longer.

The anterior end ("head") is expanded in a transversal semilunate shape and the body is the narrowest just behind the head, in a region called "neck". The dorsal color is light-brown with five black to grey longitudinal stripes that begin at the neck. The median and marginal stripes are narrow and black, very distinctly marked. The lateral stripes (between the median and marginal stripes) are usually grey, broad and with diffuse margins. The neck is usually marked by an incomplete black collar formed by the union of the marginal and lateral stripes, this being one of the main characteristics to distinguish it from similar species. The head usually has a darker color than the background color of the dorsum and lacks stripes. The ventral side has a light ochre color externally and whitish over the creeping sole, which is externally lined by two diffuse grey-violet longitudinal lines.

Bipalium kewense is believed to be native to Southeast Asia, but currently is found worldwide. It has been reported on every continent aside from Antarctica. It was probably introduced by international plant trade, as it is frequently found associated with plant pots.Winsor, L.; Johns, P. M.; Barker, G. M. (2004) "Terrestrial planarians (Platyhelminthes: Tricladida: Terricola) predaceous on terrestrial gastropods." In: Barber, G. M. (ed.) Natural enemies of terrestrial molluscs, Wallingford, CABI, 227-278.{{Cite journal | last1 = Justine | first1 = Jean-Lou | last2 = Winsor | first2 = Leigh | last3 = Gey | first3 = Delphine | last4 = Gros | first4 = Pierre | last5 = Thévenot | first5 = Jessica | title = The invasive New Guinea flatworm Platydemus manokwari in France, the first record for Europe: time for action is now | journal = PeerJ | volume = 2 | pages = e297 | year = 2014 | doi = 10.7717/peerj.297 | pmid = 24688873 | pmc = 3961122 | doi-access = free }} {{open access}}

The species was first found in 1878 in the area of the Kew Park in the London Borough of Richmond upon Thames, United Kingdom, hence the name kewense.{{Cite journal | last = Sluys | first = Ronald | title = Invasion of the Flatworms | journal = American Scientist | volume = 104 | issue = 5 | pages = 288–295 | year = 2016| doi = 10.1511/2016.122.288 }}

File:Figure 07 (PeerJ 4672) - Bipalium kewense predation.png

B. kewense is a known predator of earthworms. It immobilizes the prey using muscular movements and possibly toxins and then everts its pharynx, connecting it to the earthworm's body and beginning digestion. The digestion seems to be at least partially extracorporeal by means of a collagenolytic enzyme.{{Cite journal | last1 = Phillips | first1 = Julius | last2 = Desden | first2 = Marc. H. | title = A Collagenase in extracts of the invertebrate Bipalium kewense | year = 1973 | volume = 133 | issue = 2 | pages = 329–334 | journal = Biochemical Journal | pmc = 1177702 | pmid = 4353237 | doi=10.1042/bj1330329}}{{open access}}

Bipalium kewense is one of the few terrestrial invertebrates known to produce tetrodotoxin, a neurotoxin that results in paralysis. It is possible that the toxin aids the planarian in subduing its prey as well as in protecting it against predators.{{cite journal | last1 = Dickens | first1 = Joseph Clifton|last2=Stokes|first2=Amber N.|last3=Ducey|first3=Peter K.|last4=Neuman-Lee|first4=Lorin|last5=Hanifin|first5=Charles T. | last6 = French | first6 = Susannah S. | last7 = Pfrender | first7 = Michael E. | last8 = Brodie | first8 = Edmund D. | last9 = Brodie Jr | first9 = Edmund D. | title = Confirmation and Distribution of Tetrodotoxin for the First Time in Terrestrial Invertebrates: Two Terrestrial Flatworm Species (Bipalium adventitium and Bipalium kewense) | journal = PLOS ONE | volume = 9 | issue = 6 | year = 2014 | pages = e100718 | issn = 1932-6203 | doi = 10.1371/journal.pone.0100718 | pmid=24963791 | pmc=4070999| bibcode = 2014PLoSO...9j0718S| doi-access = free}}{{open access}}

File:Figure 09 (PeerJ 4672) - Bipalium kewense fragment.png

All species of Bipalium are hermaphroditic, but Bipalium kewense has rarely been observed using sexual reproduction as a primary means of reproduction.{{cite journal | last1 = Ducey | first1 = Peter K. | last2 = Cerqua | first2 = Jamie | last3 = West | first3 = Lori-Jeanne | last4 = Warner | first4 = Monica | last5 = Eberle | first5 = Mark E. | title = Rare egg capsule production in the invasive terrestrial planarian Bipalium kewense | journal = The Southwestern Naturalist | volume = 51 | issue = 2 | year = 2006 | pages = 252–255 | issn = 0038-4909 | doi=10.1894/0038-4909(2006)51[252:RECPIT]2.0.CO;2| s2cid = 85970661 }}

Asexual fragmentation is the primary means of reproduction in B. kewense in temperate regions. Long specimens usually release body fragments at the posterior end by transverse fission. The fragments are motile and regenerate the head plate and pharynx in a few weeks. Such a reproduction strategy is considered one reason for the successful colonization of this and other species of Bipalium.

Although there is little evidence of sexual reproduction in these planarians, there have been several reported cases of egg capsules being discovered. The egg capsules discovered had several of the same characteristics of those of B. adventitium, including coloration and incubation period. The most recent egg capsule discovered hatched offspring that did not bear a complete resemblance to adults and were considerably larger in size to that of B. adventitum offspring.

A 2018 study showed that sequences of Cytochrome c oxidase subunit I (a mitochondrial gene commonly used for barcoding) were identical for all specimens from various countries originating from several continents, suggesting that specimens were clonal. The complete mitochondrial genome, 15,666-bp in length, was obtained in 2019 form a specimen collected in France;{{cite journal|last1=Gastineau|first1=Romain|last2=Justine|first2=Jean-Lou|last3=Lemieux|first3=Claude|last4=Turmel|first4=Monique|last5=Witkowski|first5=Andrzej|title=Complete mitogenome of the giant invasive hammerhead flatworm Bipalium kewense|journal=Mitochondrial DNA Part B|volume=4|issue=1|year=2019|pages=1343–1344|issn=2380-2359|doi=10.1080/23802359.2019.1596768|doi-access=free|url=https://hal.archives-ouvertes.fr/hal-02090399/file/Gastineau%20et%20al.%20-%20Complete%20mitogenome%20Bipalium%20kewense%20-%20Mitochondrial%20DNA%20PartB%202019.pdf}} {{open access}}. In 2025, a complete mitogenome was obtained for another specimen, this time coming from Madagascar; only four differences were found between both sequences.{{Cite journal |last1=Gastineau |first1=Romain |last2=Ravelomanana |first2=Andrianjaka |last3=Ramzy |first3=Remondah Rushdy |last4=Koken |first4=Marcel |last5=Soavolamanoro |first5=Suzelyce Eva |last6=Otis |first6=Christian |last7=Boyle |first7=Brian |last8=Gey |first8=Delphine |last9=Winsor |first9=Leigh |last10=Justine |first10=Jean-Lou |date=2025-05-21 |title=First confirmed records with molecular data of the terrestrial flatworm Bipalium kewense Moseley, 1878 (Tricladida, Geoplanidae) in Madagascar, Egypt, and South Africa |url=https://checklist.pensoft.net/article/150547/ |journal=Check List |volume=21 |issue=3 |pages=557–564 |doi=10.15560/21.3.557 |doi-access=free |issn=1809-127X}} {{open access}}

{{Reflist}}

{{Taxonbar|from=Q3314783}}

Category:Geoplanidae

Category:Animals described in 1878

Category:Cosmopolitan animals