Published December 31, 2008 | Version v1
Taxonomic treatment Open

Nannoniscus Sars 1870

Description

Nannoniscus Sars, 1870

Nannoniscus Sars, 1870: 164; Hansen, 1916: 87 –89; Gurjanova, 1932: 51; Menzies, 1962b: 133; Birstein, 1963: 78; Siebenaller & Hessler, 1981: 241; Kussakin, 1999: 68.

Saetoniscus Brandt, 2002: 11, figs. 6–13.

Type species. Nannoniscus oblongus Sars, 1870.

Composition. N. acanthurus Birstein, 1963; N. aequiremus Hansen, 1916; N. affinis Hansen, 1916; N. analis Hansen, 1916; N. antennaspinis Brandt, 2002; N. arcticus Hansen, 1916; N. arctoabyssalis Just, 1980; N. australis Vanhöffen, 1914; N. bidens Vanhöffen, 1914; N. bidens sensu Brandt, 1992; N. camayae Menzies, 1962; N. caspius G. O. Sars, 1897 b; N. cristatus Mezhov, 1986; N. coalescus (Menzies & George, 1972); N. detrimentus Menzies & George, 1972; N. inermis Hansen, 1916; N. laevis Menzies, 1962; N. laticeps Hansen, 1916; N. menziesi Mezhov, 1986; N. meteori (Brandt, 2002), comb. nov.; N. minutus Hansen, 1916; N. muscarius Menzies & George, 1972; N. oblongus G. O. Sars, 1870; N. ovatus Menzies & George, 1972; N. perunis Menzies & George, 1972; N. plebejus Hansen, 1916; N. profundus Svavarsson, 1982; N. reticulatus Hansen, 1916; N. robustus Birstein, 1963; N. simplex Hansen, 1916; N. spinicornis Hansen, 1916; N. teres Siebenaller & Hessler, 1981.

Diagnosis (modified from Siebenaller & Hessler 1981:241). Pereonal tergites projecting laterally from pereopodal coxae; pereonites 6–7 dorsal articulation absent medially. Pleon distinctly shorter than pereonites 5–7. Antennula with 5 segments, distal article bulbous, article 4 distal margin with ventromedial often angular projection. Mandible with palp. Pereopods I–II equally robust. Uropods biramous.

Remarks. Siebenaller & Hessler (1981: 241) noted that further division of Nannoniscus was possible, and described several substantially different species that were retained in the genus under their concept. The pleotelson varies considerably within Nannoniscus, with species having posterolateral or posterior spines or substantially different widths to length ratios. The presence and position of ventral spines is also variable amongst the described species in the genus. All species, however, are broad bodied with distinct tergal plates extending over and laterally from the ventrally placed coxae. As discussed below, N. intermedius Siebenaller & Hessler, 1981 is transferred to Nannonisconus owing to its distinctly enlarged pleotelson, compared to all other species in the genus. Hebefustis Siebenaller & Hessler, 1977 is similar to some species of Nannoniscus, given the latter's variability in such features as ventral spination and posterolateral spines on the pleotelson. This variability leaves the absence of antennal article 4 projection as the only definitive character of Hebefustis. Siebenaller & Hessler (1981: 241) left this character out of the diagnosis of Nannoniscus.

A possibly new species was found among the published descriptions of species of Nannoniscus. Brandt (1992) did not provide evidence that specimens found in the eastern Weddell Sea were conspecific with N. bidens Vanhöffen, 1914 from Gauss­Station. Brandt's "redescription" is in fact a new record because Vanhöffen's type material was not newly described or illustrated. Brandt (1992: 147) mentions Vanhöffen's illustrations but does not discuss the appearance of his specimens, and states that specimens from the Weddell Sea were used for "redescription" (p.141). A comparison of Brandt's illustrations with those of Vanhöffen suggests that the two species are not conspecific. In particular, the antennular articles and the head shape differ substantially between the two descriptions. Because other asellote taxa in Antarctic oceans have proven to be narrow range endemics (e.g., Paramunnidae; Just & Wilson 2004), this identification should be tested by a study of Vanhöffen's 3 specimens. In the meantime, this record of N. bidens, and perhaps that of Amar & Roman (1974) should be considered as possibly new species.

Other

Published as part of Wilson, George D. F., 2008, A review of taxonomic concepts in the Nannoniscidae (Isopoda, Asellota), with a key to the genera and a description of Nannoniscus oblongus Sars, pp. 1-24 in Zootaxa 1680 on pages 13-14, DOI: 10.5281/zenodo.180391

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Linked records

Additional details

Biodiversity

Family
Nannoniscidae
Genus
Nannoniscus
Kingdom
Animalia
Order
Isopoda
Phylum
Arthropoda
Scientific name authorship
Sars
Taxon rank
genus
Taxonomic concept label
Nannoniscus Sars, 1870 sec. Wilson, 2008

References

  • Sars, G. O. (1870) Nye dybvandscrustaceer fra Lofoten. Forhandlinger I Videnskabs-Selskabet I Kristiania, 1869, 145 - 286.
  • Hansen, H. J. (1916) Crustacea Malacostraca III: Isopoda. Danish Ingolf Expedition, 3 B, 1 - 262.
  • Gurjanova, E. F. (1932) The Isopods from the Arctic. Analytical tables of the fauna of the U. S. S. R. Zoological Institute of the Academy of Sciences, Leningrad, 181 pp.
  • Menzies, R. J. (1962 b) The isopods of abyssal depths in the Atlantic Ocean. In Abyssal Crustacea. (Ed Ewing, M.) New York, Columbia University Press, pp. 79 - 206.
  • Birstein, Y. A. (1963) Glubokovodnye Ravnonogie Rakoobraznye Severo-Zapadnoi Chasti Tikhogo Okeana [Deep sea isopod crustaceans of the Northwestern part of the Pacific Ocean].) Moskova [Moscow], Izdatel'stvo Akademi l NAUK SSSR [Institute of Oceanology, Academy of Sciences, USSR]. pp. 1 - 214. (English translation, 1973, Indian National Scientific Documentation Centre, New Delhi).
  • Siebenaller, J. & Hessler, R. R. (1981) The genera of the Nannoniscidae (Isopoda, Asellota). Transactions of the San Diego Society of Natural History, 19, 227 - 250.
  • Kussakin, O. G. (1999) Morskye I solonovatovodnye ravnonogie rakoobrasnye (Isopoda) cholodnix I umerennix vod severnogo polushariya [Marine and brackishwater likefooted Crustacea (Isopoda) from the cold and temperate waters of the Northern Hemisphere] Suborder Asellota. Part 2. Families Joeropsididae, Nannoniscidae, Desmosomatidae, Macrostylidae). Opredeliteli po Faune SSSR [Determinants of the Fauna], Izdavaemye Zoologischeskim Institutom Rossiiskiya Akademiya Nauk. (Ed A. F. Alimov.) St. Petersburg, NAUKA. Vol. III, pp. 1 - 383.
  • Brandt, A. (2002) New species of Nannoniscidae (Crustacea, Isopoda) and Saetoniscus n. gen. from the deep sea of the Angola Basin. Zootaxa, 88, 1 - 36.
  • Just, J. (1980) Polar sea abyssal and deep bathyal Isopoda (Crustacea). Steenstrupia, 6, 197 - 230.
  • Vanhoffen, E. (1914) Die Isopoden der Deutschen Sudpolar-Expedition 1901 - 1903. Deutsche Sudpolar-Expedition 1901 - 1903, 15, 447 - 598.
  • Brandt, A. (1992) Nannoniscus bidens Vanhoffen, 1914 from West Antarctica (Crustacea, Isopoda, Nannoniscidae). Zoologischer Anzeiger, 228, 140 - 148.
  • Sars, G. O. (1897 b) On some additional Crustacea from the Caspian Sea. Annales du Musee Zoologique Academie Imperiale des Sciences, St Petersbourg, 2, 273 - 305.
  • Mezhov, B. V. (1986) Bathyal and abyssal Nannoniscidae and Desmosomatidae (Isopoda, Asellota) from Alaska Bay. Archives of the Zoological Museum, Moscow State University, 24, 126 - 167.
  • Menzies, R. J. & George, R. Y. (1972) Isopod Crustacea of the Peru-Chile Trench. Anton Bruun Report, 9, 1 - 124.
  • Svavarsson, J. (1982) Nannoniscus profundus sp. n. and Austroniscus norbi sp. n. (Isopoda, Asellota, Nannoniscidae) from the deep Norwegian Sea. Sarsia, 67, 179 - 186.
  • Siebenaller, J. & Hessler, R. R. (1977) The Nannoniscidae (Isopoda, Asellota): Hebefustis n. gen. and Nannoniscoides Hansen. Transactions of the San Diego Society of Natural History, 19, 17 - 44.
  • Just, J. & Wilson, G. D. F. (2004) Revision of the Paramunna complex (Isopoda: Asellota: Paramunnidae). Invertebrate Systematics, 18, 377 - 466.
  • Amar, R. & Roman, M. - L. (1974) Invertebres Marins des XIIeme et XVeme Expeditions Antarctiques Francaises en Terre Adelie. 14. Tanaidaces et Isopodes. Tethys, 5, 561 - 600.