| 词条 | Cancrocaeca |
| 释义 |
| name = Cancrocaeca xenomorpha | regnum = Animalia | phylum = Arthropoda | subphylum = Crustacea | classis = Malacostraca | ordo = Decapoda | infraordo = Brachyura | familia = Hymenosomatidae | genus = Cancrocaeca | genus_authority = Ng, 1991 | species = C. xenomorpha | binomial = Cancrocaeca xenomorpha | binomial_authority = Ng, 1991 }}Cancrocaeca xenomorpha is a species of troglobitic (cave-dwelling) freshwater crab from Sulawesi, the only species in the monotypic genus Cancrocaeca. It has been described as the world's "most highly cave-adapted species of crab".[1] DescriptionCancrocaeca xenomorpha is a small crab with long legs.[1] It has no eyes or even vestiges of eyestalks, and has only vague depressions where the orbits of the eyes might be expected; this is the greatest degree of ocular degeneration of any crab.[1] The carapace is rounded in outline, without any rostrum, and is slightly wider than it is long.[1] The five pairs of legs are very long, at up to 3.7 times the width of the carapace in length.[1]Females are slightly larger than males, at up to {{convert|6.2|x|5.6|mm|abbr=on}} across the carapace, compared to {{convert|4.7|x|4.1|mm|abbr=on}} for males. Females also appear to be a darker colour, but only because of the presence of mud particles on the carapace; both sexes are naturally unpigmented.[1] DistributionCancrocaeca is known only from fresh water in three karstic caves in Maros Regency, Sulawesi (Indonesia).[2] At the time of its discovery, no troglobitic members of the family Hymenosomatidae were known, although Danièle Guinot had predicted in 1988 that the family was a likely candidate to produce troglobites.[3] Since that time, further troglobitic species have been discovered in the same family; although they resemble Cancrocaeca superficially, this is thought to result from convergent evolution,[3] and it is thought likely that Cancrocaeca arose recently from marine ancestors.[4]BiologyThe biology of Cancrocaeca is almost entirely unknown.[2] The original collections were often found in association with pieces of driftwood washed into the caves from outside, and were found in water at about {{convert|25.8|C|F}}.[1] The eggs are around {{convert|0.6|mm}} in diameter, requiring gonopores that are 15%–25% as wide as the sternum.[1] Because its eggs are large, it is thought that the larval development may be abbreviated, and that the species may even show direct development, hatching from the eggs as juvenile crabs, rather than as larvae.[1][2] Taxonomic historyCancrocaeca was discovered in a cave in southern Sulawesi in 1989, as part of an expedition by the {{lang|fr|Association Pyrénéenne de Spéléologie}} ("Pyrenean Speleological Association"); the expedition collected a number of crabs and sent them to Peter K. L. Ng of the National University of Singapore for identification. Among a large number of Parathelphusa specimens, he discovered a single male of Cancrocaeca. A subsequent expedition in 1990 provided further specimens, including females. The species was described, in a new genus, in a 1991 publication in the Raffles Bulletin of Zoology.[1] The genus name Cancrocaeca derives from {{lang|la|cancer}}, the Latin for "crab", and {{lang|la|caecus}}, Latin for "blind". The specific epithet xenomorpha is from the Greek roots {{lang|el|ξένος}} (xénos, "strange") and {{lang|el|μορφόω}} (morphós, "form"), because of the crab's unusual features.[1]References1. ^1 2 3 4 5 6 7 8 9 {{cite journal |author=P. K. L. Ng |year=1991 |title=Cancrocaeca xenomorpha, new genus and species, a blind troglobitic freshwater hymenosomatid (Crustacea: Decapoda: Brachyura) from Sulawesi, Indonesia |journal=Raffles Bulletin of Zoology |volume=39 |issue=1 |pages=59–73 |url=http://rmbr.nus.edu.sg/rbz/biblio/39/39rbz059-073.pdf |format=PDF}} {{Taxonbar|from=Q5031534}}2. ^1 2 3 {{cite web |title=False spider cave crab, (Cancrocaeca xenomorpha) |author=L. Deharveng, D. Guinot & P.K.L. Ng |publisher=ASEAN Regional Centre for Biodiversity Conservation |url=http://www.arcbc.org.ph/arcbcweb/pdf/vol2no2/focus_false_spider_cave_crab.pdf |format=PDF |accessdate=September 21, 2012}} 3. ^1 {{cite journal |author=Tohru Naruse, Peter K. L. Ng & Danièle Guinot |year=2008 |title=Two new genera and two new species of troglobitis false spider crabs (Crustacea: Decapoda: Brachyura: Hymenosomatidae) from Indonesia, with notes on Cancrocaeca Ng, 1991 |journal=Zootaxa |volume=1739 |pages=21–40 |url=http://www.mapress.com/zootaxa/2008/f/z01739p040f.pdf |format=PDF excerpt}} 4. ^{{cite book |editor=William B. White & David C. Culver |year=2012 |title=Encyclopedia of Caves |edition=2nd |publisher=Academic Press |isbn=9780123838322 |chapter=Diversity patterns in the tropics |author=Louis Deharveng & Anne Bedos |pages=238–250 |url=https://books.google.com/books?id=alDky3N0CmkC&pg=PA249}} 5 : Majoidea|Freshwater crustaceans of Asia|Cave crustaceans|Crustaceans of Indonesia|Monotypic crustacean genera |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。