''Macrochlaena winckworthi'', Winckworth's octopus, is a little known species of

octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...

, it is the only species in the monotypic genus ''Macrochlaena'', in the family Octopodidae. It was described by the British malacologist Guy Coburn Robson in 1926, the type specimens having been collected in the Gulf of Mannar, off Thoothukudi in Tamil Nadu, southeastern India.

Description

''Macrochlaena winckworthi'' is a small species of octopus with relatively short arms, the arms being 1.5-2.5 times longer than the

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

with the lateral arms being slightly longer. The web is relatively deep, being one third the length of the arms, and the web is slightly deeper between the lateral arms. There are no pouches between the arms. Each arm has two rows of small suckers n its underside, with each arm having around 65 suckers. The funnel organ has a shape described as "UU" and the gills have 8 to 10 lamellae per demibranch. The

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

has 9 elements, 7 teeth rows and marginal plates and the rachidian tooth has a single lateral cusp in a symmetrical series. It possesses a small

ink sac An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all Coleoidea (squid, octopus and cuttlefish) which dwell ...

. In the males the third right arm is

hectocotylised A hectocotylus (plural: ''hectocotyli'') is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use i ...

being approximately 80% of the length of the opposite arm and having 35 to 40 suckers. The terminal organ is linear and the

diverticulum In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...

is simple in form with a slightly swollen shape. It has small spermatophores each being 8 to 10 mm in length, roughly one third of the length of the mantle. The head is now dsitnguished much from the mantle and the eyes are rather small. The skin is smooth and overall the animal is red-brown to purple in colour with a marbling of darker mottles. The total length of an adult is at least 93mm, the mantle length is 33mm.

Habitat and distribution

''Macrochlaena winckworthi'' was originally collected from pearl oyster beds in shallow water off the coast of Tamil Nadu in the Gulf of Mannar. It has also been collected off Java and it has been inferred that its distribution extends from India east to the

Malay Archipelago The Malay Archipelago (Indonesian/Malay: , tgl, Kapuluang Malay) is the archipelago between mainland Indochina and Australia. It has also been called the " Malay world," "Nusantara", "East Indies", Indo-Australian Archipelago, Spices Archipe ...

in shallow waters of less than 20m in depth. It seems to have some convergent adaptations with other species of octopods which live in muddy habitats. This is a little known species and its biology and behaviour are unknown, as is its importance in any fisheries.

References

{{Taxonbar, from=Q18579970 Octopuses Cephalopod genera Molluscs described in 1926