Colossendeis
Colossendeis is a genus of sea spider belonging to the family Colossendeidae. These sea spiders are typically found in the deep sea. This genus includes the largest pycnogonids, with leg spans frequently ranging from 40 to 50 cm. The largest sea spider, Colossendeis colossea, can reach a leg span of 70 cm. This genus also includes some bioluminescent sea spiders.
Description
Sea spiders in this genus feature an unsegmented trunk, a low ocular tubercle, and a well-developed abdomen. Chelifores are absent in adults. The palps and ovigers touch at their bases, and the strigilis is tightly curved with a strong terminal claw. Species in this genus have only four pairs of legs. The ventral surface of the second most proximal article of some or all of these legs features tiny genital pores.
Feeding
Sea spiders in this genus feed on cnidarians, sponges, bryozoans, small mollusks, and small polychaetes.
Phylogeny
Although all species in this genus are eight-legged, phylogenetic analysis based on molecular data indicates that this genus is paraphyletic with respect to the ten-legged genus Decolopoda and the twelve-legged genus Dodecolopoda; these two polymerous genera are nested within the genus Colossendeis in a phylogenetic tree. This paraphyly would normally make both Dodecolopoda and Colossendeis junior synonyms of Decolopoda, the oldest name, and require all three genera to merge under the name Decolopoda. To avoid this disruption, authorities keep these genera under different names and retain Colossendeis as a paraphyletic genus.
The molecular evidence also indicates that both Decolopoda and Dodecolopoda are nested within a monophyletic group containing the "longitarsal" species in the genus Colossendeis. The sea spiders in this "longitarsal" clade feature legs in which the three most distal articles taken together are at least three-quarters the length of the fourth most distal article. This clade includes not only Antarctic species of Colossendeis such as C. australis and C. glacialis but also widespread taxa such as C. megalonyx and C. robusta. In "brevitarsal" species, such as C. macerrima, the three most distal articles are instead much shorter relative to the second tibia.
Species
There are 72 species:Colossendeis acuta Stiboy-Risch, 1993Colossendeis adelpha Child, 1998Colossendeis angusta Sars, 1877Colossendeis aperta Turpaeva, 2005Colossendeis arcanus Turpaeva, 2008Colossendeis arcuata A. Milne-Edwards, 1885Colossendeis australis Hodgson, 1907Colossendeis avidus Pushkin, 1970Colossendeis belekurovi Pushkin, 1993Colossendeis bicincta Schimkewitsch, 1893Colossendeis bouvetensis Dietz, Pieper, Seefeldt & Leese, 2015Colossendeis brevirostris Child, 1995Colossendeis bruuni Fage, 1956Colossendeis clavata Meinert, 1899Colossendeis colossea Wilson, 1881Colossendeis concedis Child, 1995Colossendeis cucurbita Cole, 1909Colossendeis curtirostris Stock, 1963Colossendeis dalli Child, 1995Colossendeis drakei Calman, 1915Colossendeis elephantis Child, 1995Colossendeis enigmatica Turpaeva, 1974Colossendeis ensifer Child, 1995Colossendeis fijigrypos Bamber, 2004Colossendeis fragilis Pushkin, 1993Colossendeis gardineri Carpenter, 1907Colossendeis geoffroyi Mane-Garzon, 1944Colossendeis glacialis Hodgson, 1907Colossendeis gracilis Hoek, 1881Colossendeis grassus Pushkin, 1993Colossendeis hoeki Gordon, 1944Colossendeis insolitus Pushkin, 1993Colossendeis korotkevitschi Pushkin, 1984Colossendeis kurtchatovi Turpaeva, 1993Colossendeis leniensis Pushkin, 1993Colossendeis leptorhynchus Hoek, 1881Colossendeis longirostris Gordon, 1938Colossendeis losinskii Turpaeva, 2002Colossendeis macerrima Wilson, 1881Colossendeis media Hoek, 1881Colossendeis megalonyx Hoek, 1881Colossendeis melancholicus Stock, 1975Colossendeis mica Pushkin, 1970Colossendeis microsetosa Hilton, 1943Colossendeis minor Schimkewitsch, 1893Colossendeis minuta Hoek, 1881Colossendeis mycterismos Bamber, 2004Colossendeis nasuta Hedgpeth, 1949Colossendeis notialis Child, 1995Colossendeis oculifera Stock, 1963Colossendeis peloria Child, 1994Colossendeis perforata Turpaeva, 1993Colossendeis pipetta Stock, 1991Colossendeis potentis Turpaeva, 2008Colossendeis proboscidea Colossendeis pseudochelata Pushkin, 1993Colossendeis robusta Hoek, 1881Colossendeis rostrata Turpaeva, 1994Colossendeis scoresbii Gordon, 1932Colossendeis scotti Calman, 1915Colossendeis sinuosa Stock, 1997Colossendeis spicula Child, 1994Colossendeis stramenti Fry & Hedgpeth, 1969Colossendeis subminuta Schimkewitsch, 1893Colossendeis tasmanica Staples, 2007Colossendeis tenera Hilton, 1943Colossendeis tenuipedis Pushkin, 1993Colossendeis tethya Turpaeva, 1974Colossendeis tortipalpis Gordon, 1932Colossendeis vityazi Turpaeva, 1973Colossendeis weddellensis Turpaeva, 2008Colossendeis wilsoni Calman, 1915