• IDIOSEPIIDAE Appellöf, A. 1898. Cephalopoden von Ternate. 1. Verzeichniss der von professor Kükenthal gesammelten Arten. II. Untersuchungen über Idiosepius, Sepiodarium und verwandte Formen, ein Beitrag zur Beleuchtung der Hektokotylisation und ihrer systematischen Bedeutung. Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft 24: 561-637.

  Type genus:

   Idiosepius Steenstrup, 1881.

Introduction

Members of the family Idiosepiidae Appellöf, 1898 are the smallest of all cephalopods (known maximum size of mature males 17 mm, females 22 mm). The family is distributed in the Indo-west Pacific from Japan to Australia, and South Africa. It has not been reported from Atlantic waters. Nine nominal species are known in three genera. In Australian waters, Idiosepius pygmaeus Steenstrup, 1881 and I. paradoxus (Ortmann, 1888) are known from the Northern Territory and Queensland waters; the southern limit of their distributions have not been established. Idiosepius hallami Reid & Strugnell, 2018 is known to occur from southern Queensland (22° S) to southern NSW (36° S) and Xipholeptos notoides (Berry, 1921), is known from southern Australia from southern New South Wales to South Australia, including Tasmania. The latter two species are Australian endemics. Specimens of Xipholeptos from Western Australia were shown to comprise a clade distinct from the southern and eastern Australian clade in Reid and Strugnell (2018). Whether distinct species recognition is justified for the Western Australian population is yet to be determined.

The type species of the family, Idiosepius pygmaeus was first described by Steenstrup in 1881 from specimens collected in a surface net at 4°20'N 107°20'E, as well as a specimen from Zamboango. Berry (1921) reported the first Australian record of the family from South Australia, naming it Idiosepius notoides. Allan (1945) reported the presence of Idiosepius pygmaeus in Australia. Cotton and Godfrey (1940) also recorded I. paradoxus as from Australia. Lu & Phillips (1985) questioned the validity of the records for I. pygmaeus and I. paradoxus as no specimens of either were available for examination. Subsequent collections have confirmed the occurrence of both species, as well as X. notoides, in Australian waters.

This family is characterised by lack of an external shell and presence of a vestigial chitinous internal shell. A unique oval adhesive organ present on the dorsal surface of the mantle is used by the animal to attach itself to seaweed or seagrass blades. This glandular organ is located chiefly in the integument layer; its external surface is uneven with irregularly arranged furrows and pits. Adhesion of the animal is achieved by a sticky substance secreted by the organ (Sasaki 1923, Byern et al. , 2008).

Idiosepids are commonly found in seagrass beds where they attach to the undersides of leaves. In Japan, I. paradoxus was found to feed chiefly on gammalid amphipods as large as its own body (Sasaki 1929). The predator bites the back of the prey just at the point where the heart is located. The animal is able to extend its buccal mass to as long as its first arm, and move it freely in all directions. By doing so, it can eat out the soft flesh of the prey without the external chitinous skin being broken.

Natsukari (1970) reported on the egg-laying behaviour and embryonic development of Idiosepius paradoxus in western Japan. A female laid eggs once or twice at three day intervals and can lay 25 to 64 eggs in total. One or two days after the final egg-laying, the female died. In captivity, in glass jars, the female adhered upside-down to the bottom of the jar. She ejected eggs one at a time from the funnel, receiving the egg in her arms. She then positioned herself by grasping the bottom with the dorsal three pairs of arms and stuck the egg to the bottom, using her tentacles. After sticking an egg, she slid backwards by hard flapping of her fins and repeated the egg laying process, taking about 30 seconds each time. The egg is elliptical in shape, measuring 0.87–0.91 mm in length and 0.67–0.72 mm in width. The incubation period of the eggs is 15–17 days at an ambient water temperature of 18.5–22.6°C.

English (1981) reported that an aquarium-kept Idiosepius species from the Sydney area, laid eggs on the side wall of the tank beneath pieces of aquarium tubing, or on the undersides of seagrass leaves. She suggested that under natural conditions, this species of Idiosepius (likely I. hallami lays its eggs on hard substrata such as bivalve shells or the undersides of blades of seagrass. The main breeding period is reported to be through the spring and summer; the life span is reported to be approximately 12–15 months.

Jackson (1986) studied Idiosepius from northern Queensland and confirmed the occurrence of both I. pygmaeus and I. paradoxus in the Townsville area. Adults of Idiosepius paradoxus are planktonic while those of I. pygmaeus have a more nektonic life. The two species show some degree of niche separation. Idiosepius pygmaeus has adapted to an estuarine existence while I. paradoxus has successfully established in the continental shelf plankton community. Studies on Idiosepius pygmaeus in the tropical water of Australia show that it has faster growth rates and shorter life spans than I. paradoxus: males mature as young as 42 days old and females as young as 60 days. The greatest ages recorded for individuals were 67 days for males and 79 days for females (Jackson 1988; Jackson & Choat 1992).

Other references to the biology and behaviour of Idiosepiidae are cited in Reid (2016), Reid & Strugnell (2018) and Reid et al. 2023.

Diagnosis

The mantle is elongate, slightly pointed at the posterior end. An oval attachment organ is located on the dorsal surface of the mantle. The fins are small and kidney-shaped, and are attached laterally at the posterior end of the mantle, at a slightly oblique angle in relation to the longitudinal body axis. The anterior edge of the mantle is not fused with the head. The head is prominent with large, bulbous eyes that are covered by a cornea. The nuchal cartilage is lacking. The funnel-mantle locking cartilage is peg-like in all except the southern Australian species, Xipholeptos notoides, which has a simple, straight cartilage. The arms are short with two rows of suckers. The tentacles are slender, short and retractile. The tentacular clubs are not expanded, with two to four rows of suckers. Both ventral arms of mature males are hectocotylised. The modification involves loss of suckers on most of the arms and the tip of left ventral arms become bilobed.

General References

Allan, J. 1945. Planktonic cephalopod larvae from the eastern Australian coast. Records of the Australian Museum 21: 317-350 pls 24-27

Berry, S.S. 1921. A review of the cephalopod genera Sepioloidea, Sepiadarium and Idiosepius. Records of the South Australian Museum (Adelaide) 1: 347-364

Byern,J. von, Rudoll, L., Cyran, N. & Klepal, W. 2008. Histochemical characterization of the adhesive organ of three Idiosepius spp. species. Biotechnic and Histochemistry 83: 29-46

Cotton, B.C. & Godfrey, F.K. 1940. The Molluscs of South Australia. Part 2. Scaphopoda, Cephalopoda, Aplacophora and Crepipoda. Adelaide : Government Printer 600 pp.

English, S.A. 1981. The biology of two species of estuarine cephalopods from the Sydney region. Unpublished MSc Thesis, University of Sydney, Sydney 125 pp.

Hylleberg, J. & Nateewathana, A. 1991. Redescription of Idiosepius pygmaeus Steenstrup, 1881 (Cephalopoda: Idiosepiidae), with mention of additional morphological characters. Phuket Marine Biological Center, Research Bulletin 55: 33-42

Jackson, G.D. 1986. A biological and ecological survey of the planktonic Cephalopoda in the waters of the central Great Barrier Reef Region with emphasis on the biology and ageing of the sepioid Idiosepius pygmaeus. Unpublished BSc (Hons) Thesis, James Cook University of North Queensland, Townsville 87 pp.

Jackson, G.D. 1988. The use of statolith microstructures to analyze life-history events in the small tropical cephalopod Idisepius pygmaeus. United States Department of Agriculture. Cooperative Economic Insect Report 87: 265-272

Jackson, G.D. & Choat, J.H. 1992. Growth in tropical cephalopods: an analysis based on statolith microstructure. Canadian Journal of Fisheries and Aquatic Sciences [formerly Journal of the Fisheries Research Board of Canada] 49(2): 218-228

Lu, C.C. & Phillips, J.U. 1985. An annotated checklist of Cephalopoda from Australian waters. Occasional Papers of the Museum of Victoria 2: 21-36

Natsukari, Y. 1970. Egg-laying behaviour, embryonic development and hatched larva of the pygmy cuttlefish, Idiosepius pygmaeus paradoxus Ortmann. Bulletin of the Faculty of Fisheries, Nagasaki University 30: 15-29

Reid, A. 2016. Cephalopods of Australia and Sub-Antarctic Territories. Clayton South, Victoria : CSIRO Publishing pp. 446.

Reid, A., Sato, N., Jolly, J. & Strugnell, J. 2023. Two new pygmy squids, Idiosepius kijimuna n. sp. and Kodama jujutsu n. gen., n. sp. from the Ryukyu Islands, Japan. Marine Biology 170 167

Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486

Sasaki, M. 1923. On an adhering habit of a pygmy cuttlefish, Idiosepius pygmaeus Steenstrup. Annotationes Zoologicae Japonenses 10(21): 209-213

Sasaki, M. 1929. A monograph of the dibranchiate cephalopods of the Japanese and adjacent waters. Journal of the Faculty of Agriculture, Hokkaido Imperial University 20(Suppl.): 1-357 30 pls

Steenstrup, J.J. 1881. Sepiadarium og Idiosepius to nye slaegter af Sepiernes familie. Med Bemaerkninger om de to beslaegtede former Sepioloidea d'Orb. og Spirula Lamarck. Kongelige Danske Videnskabernes. Selskabs Skrifter. Kjøbenhavn 6: 213-242

History of changes

• Idiosepius Steenstrup, J.J. 1881. Sepiadarium og Idiosepius to nye slaegter af Sepiernes familie. Med Bemaerkninger om de to beslaegtede former Sepioloidea d'Orb. og Spirula Lamarck. Kongelige Danske Videnskabernes. Selskabs Skrifter. Kjøbenhavn 6: 213-242 [219].

  Type species:

   Idiosepius pygmaeus Steenstrup, 1881 by monotypy.
• Microteuthis Ortmann, A. 1888. Japanische Cephalopoden. Zoologische Jahrbücher. Abteilung für Systematik 3: 639-670 [648].

  Type species:

   Microteuthis paradoxa Ortmann, 1888 by monotypy.

Taxonomic Decision for Synonymy

• Berry, S.S. 1921. A review of the cephalopod genera Sepioloidea, Sepiadarium and Idiosepius. Records of the South Australian Museum (Adelaide) 1: 347-364 [355]

Distribution

States

New South Wales, Northern Territory, Queensland

Extra Distribution Information

Indo-Pacific region.

IMCRA

Timor Transition (1), Northern Shelf Province (25), Northwest Shelf Transition (26), Southeast Shelf Transition (37), Central Eastern Shelf Province (38), Central Eastern Shelf Transition (39), Northeast Shelf Province (40), Northeast Shelf Transition (41)

Other Regions

Lord Howe Island terrestrial & freshwater

Distribution References

General References

Reid, A. 2005. Family Idiosepiidae. pp. 208-210 in Jereb, P. & Roper, C.F.E. (Eds). Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for Fishery Purposes. No. 4 Rome : FAO Vol. 1 pp. 1-262. [208]

Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486 [457]

History of changes

• Idiosepius hallami Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486 [457, Figs 1–6, 10a; Tables 2, 3, 5].

  Type data:

   Holotype AM C.269565 ♂, Warilla, Whyjuck Bay, off Boonerah Pt, Lake Illawarra, NSW [34°32 ́33 ́ ́S, 150°50 ́12 ́ ́E].
  Paratype(s) AM C.483479 3♂, 7♀, Warilla, Whyjuck Bay, off Boonerah Pt, Lake Illawarra, NSW [34°32 ́33 ́ ́S, 150°50 ́12 ́ ́E]; AM numerous specimens, Warilla, Whyjuck Bay, off Boonerah Pt, Lake Illawarra, NSW [34°32 ́33 ́ ́S, 150°50 ́12 ́ ́E].
• Idiosepius paradoxus Lu, C.C. & Phillips, J.U. 1985. An annotated checklist of Cephalopoda from Australian waters. Occasional Papers of the Museum of Victoria 2: 21-36 [28].
• Idiosepius sp. nov. Reid, A. 2016. Cephalopods of Australia and Sub-Antarctic Territories. Clayton South, Victoria : CSIRO Publishing pp. 446. [35-36]

Distribution

States

New South Wales, Queensland

Extra Distribution Information

Australian Endemic.

IMCRA

Southeast Shelf Transition (37), Central Eastern Shelf Province (38), Central Eastern Shelf Transition (39), Northeast Shelf Province (40)

Other Regions

Lord Howe Island terrestrial & freshwater

Distribution References

History of changes

• Microteuthis paradoxus Ortmann, A. 1888. Japanische Cephalopoden. Zoologische Jahrbücher. Abteilung für Systematik 3: 639-670 [649].

  Type data:

   Holotype MZUS, Kadysiama, Japan.

  Secondary source:

   Sasaki, M. 1929. A monograph of the dibranchiate cephalopods of the Japanese and adjacent waters. Journal of the Faculty of Agriculture, Hokkaido Imperial University 20(Suppl.): 1-357 30 pls.

Generic Combinations

• Idiosepius paradoxus (Ortmann, 1888).

Distribution

States

Queensland

Extra Distribution Information

Northern Australia

IMCRA

Central Eastern Shelf Transition (39), Northeast Shelf Province (40), Northeast Shelf Transition (41)

Distribution References

Ecological Descriptors

Coastal, tropical.

General References

Lu, C.C. & Phillips, J.U. 1985. An annotated checklist of Cephalopoda from Australian waters. Occasional Papers of the Museum of Victoria 2: 21-36 [28] (Australian distribution)

Norman, M. 2000. Cephalopods, a world guide. Hakenheim : ConchBooks 320 pp. [129] (biology)

Reid, A. 2005. Family Idiosepiidae. pp. 208-210 in Jereb, P. & Roper, C.F.E. (Eds). Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for Fishery Purposes. No. 4 Rome : FAO Vol. 1 pp. 1-262. [209] (geographical distribution)

Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486 [468, Table 5]

Robson, G.C. 1928. Céphalopodes des mers d'Indochine. Notes. Station Maritime de Cauda 10: 1-53 (Australian distribution)

Common Name References

Norman, M. 2000. Cephalopods, a world guide. Hakenheim : ConchBooks 320 pp. [129] (Northern Pygmy Squid)

History of changes

• Idiosepius pygmaeus Steenstrup, J.J. 1881. Sepiadarium og Idiosepius to nye slaegter af Sepiernes familie. Med Bemaerkninger om de to beslaegtede former Sepioloidea d'Orb. og Spirula Lamarck. Kongelige Danske Videnskabernes. Selskabs Skrifter. Kjøbenhavn 6: 213-242 [219].

  Type data:

   Holotype Indian Sea.

  Secondary source:

   Rochebrune, A.T. 1884. Etude monographique de la famille des Sepiadae. Bulletin de la Société Philomathique de Paris 7 8: 74-122 pls 3-6.

Distribution

States

Northern Territory, Queensland

Extra Distribution Information

Northern and northeastern Australia. Shallow inshore waters.

IMCRA

Timor Transition (1), Northern Shelf Province (25), Northwest Shelf Transition (26), Northeast Shelf Province (40), Northeast Shelf Transition (41)

Distribution References

Ecological Descriptors

Coastal, temperate, tropical.

General References

Jackson, G.D. 1988. The use of statolith microstructures to analyze life-history events in the small tropical cephalopod Idisepius pygmaeus. United States Department of Agriculture. Cooperative Economic Insect Report 87: 265-272 (growth)

Jackson, G.D. 1992. Seasonal abundance of the small tropical sepioid Idiosepius pygmaeus (Cephalopoda: Idiosepiidae) at two localities off Townsville, north Queensland, Australia. Veliger 35(4): 396-401 (abundance)

Jackson, G.D. 1993. Seasonal variation in reproductive investment in the tropical loliginid squid Loligo chinensis and the small tropical sepioid Idiosepius pygmaeus. United States Fisheries Bulletin 91: 260-270 (reproduction)

Jackson, G.D. & Choat, J.H. 1992. Growth in tropical cephalopods: an analysis based on statolith microstructure. Canadian Journal of Fisheries and Aquatic Sciences [formerly Journal of the Fisheries Research Board of Canada] 49(2): 218-228 (growth)

Lewis, A.R. & Choat, J.H. 1993. Spawning mode and reproductive output of the tropical cephalopod Idiosepius pygmaeus. Canadian Journal of Fisheries and Aquatic Sciences [formerly Journal of the Fisheries Research Board of Canada] 50(1): 20-28 (reproduction)

Lu, C.C. & Phillips, J.U. 1985. An annotated checklist of Cephalopoda from Australian waters. Occasional Papers of the Museum of Victoria 2: 21-36 [28] (Australian distrbution)

Norman, M. 2000. Cephalopods, a world guide. Hakenheim : ConchBooks 320 pp. [129] (biology)

Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486 [469, Table 5]

Robson, G.C. 1928. Céphalopodes des mers d'Indochine. Notes. Station Maritime de Cauda 10: 1-53 (Australian distribution)

Common Name References

Norman, M. 2000. Cephalopods, a world guide. Hakenheim : ConchBooks 320 pp. [129] (Two-tone Pygmy Squid)

History of changes

• Xipholeptos Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486.

Distribution

States

New South Wales, South Australia, Tasmania, Victoria

IMCRA

Spencer Gulf Shelf Province (33), Western Bass Strait Shelf Transition (34), Bass Strait Shelf Province (35), Tasmanian Shelf Province (36), Southeast Shelf Transition (37)

History of changes

• Idiosepius notoides Berry, S.S. 1921. A review of the cephalopod genera Sepioloidea, Sepiadarium and Idiosepius. Records of the South Australian Museum (Adelaide) 1: 347-364 [361].

  Type data:

   Holotype D17495 ♂, SA, Goolwa.

Generic Combinations

• Xipholeptos notoides (Berry, 1921). —
  Reid, A.L. & Strugnell, J.M. 2018. A new pygmy squid, Idiosepius hallami n. sp. (Cephalopoda: Idiosepiidae) from eastern Australia and elevation of the southern endemic ‘notoides’ clade to a new genus, Xipholeptos n. gen. Zootaxa 4369(4): 451-486 [472, Figs 6, 8-9, 10b-e]

Distribution

States

New South Wales, South Australia, Tasmania, Victoria

Extra Distribution Information

Southern and eastern Australia. Shallow inshore waters.

Australian Endemic.

IMCRA

Spencer Gulf Shelf Province (33), Western Bass Strait Shelf Transition (34), Bass Strait Shelf Province (35), Tasmanian Shelf Province (36), Southeast Shelf Transition (37)

Distribution References

Ecological Descriptors

Coastal, marine, temperate.

General References

Lu, C.C. & Phillips, J.U. 1985. An annotated checklist of Cephalopoda from Australian waters. Occasional Papers of the Museum of Victoria 2: 21-36 ((Australian distribution))

Norman, M. 2000. Cephalopods, a world guide. Hakenheim : ConchBooks 320 pp. [127] ((biology))

Reid, A. 2005. Family Idiosepiidae. pp. 208-210 in Jereb, P. & Roper, C.F.E. (Eds). Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for Fishery Purposes. No. 4 Rome : FAO Vol. 1 pp. 1-262. [2009] ((geographical distribution))

Common Name References

Norman, M.D. & Reid, A.L. 2000. A Guide to Squid, Cuttlefish and Octopus of Australasia. Collingwood : CSIRO Publishing 96 pp. [38] ((Southern Pygmy Squid)) (Southern Pygmy Squid)

History of changes