Diplostraca

Lynceus brachyurus, from here.

Belongs within: Branchiopoda.
Contains: Eosestheria, Spinicaudata, Cladoceromorpha.

The Diplostraca is a clade of freshwater crustaceans with the body enclosed within a bivalved carapace. They have a fossil record extending back to the early Devonian (Briggs et al. 1993). The diplostracans have been divided in the past between the Cladocera (water fleas) and 'Conchostraca' (clam shrimps) with the Conchostraca having a more expansive carapace and retaining posterior appendages. However, current indications are that the clam shrimps are paraphyletic with the Spinicaudata being more closely related to the Cladocera than to the Lynceidae.

The clam shrimps of the Lynceidae have a smooth carapace without growth lines, and a greatly reduced telson lacking a furca. They have a less extensive fossil record than the Spinicaudata, going back only to the Cretaceous (Briggs et al. 1993), suggesting the existence of a long ghost lineage.

Synapomorphies (from Ax 1999): Median placement of compound eyes in close proximity; second antenna biramous, strongly developed with locomotory function; first thoracopod of male with hooks for copulation, movable finger differentiated from endopodite; eggs deposited in dorsal shell space between carapace and back of thorax, eggs attached onto dorsal structures of endopodite; abdomen short, legless, folded downwards; dorsal telson with pair of long setae; branches of furca differentiated into backward-directed claws.

<==Diplostraca [Conchostraca, Onychura]
    |--+--Spinicaudata LSE13
    |  `--Cladoceromorpha LSE13
    `--Lynceidae [Laevicauda, Laevicaudata, Laeviscaudata, Lyncaeidae] RS10
         |--Camptocercus lilljeborgii D01
         |--Acroperus leucocephalus D01
         |--Duvenhedia setigera D01
         |--Pleuroxus D01
         |    |--P. aduncus D01
         |    |--P. csikii Daday 1901 D01
         |    |--P. excisus D01
         |    |--P. hastatus D01
         |    |--P. personatus D01
         |    |--P. trigonellus D01
         |    `--P. truncatus D01
         `--Lynceus LSE13
              |--L. branchyurus G20 [=Monoculus brachyurus L02]
              |--L. lamellatus [=Monoculus lamellatus] L02
              |--L. longirostris [=Monoculus longirostris] L02
              |--L. macleayanus T06
              |--L. macrourus [=Monoculus macrourus] L02
              |--L. quadrangularis [=Monoculus quadrangularis] L02
              |--L. socors [=Monoculus socors] L02
              |--L. sphaericus [=Monoculus sphaericus] L02
              |--L. stschukini Chernyshev 1940 BWW93
              |--L. trigonellus [=Monoculus trigonellus] L02
              `--L. truncatus [=Monoculus truncatus] L02

Diplostraca incertae sedis:
  Bairdestheria S02
  Eosestheria S81
  Diestheria S81
    |--D. gansuensis S81
    |--D. jiayuguanensis S81
    |--D. ovalis S81
    |--D. xiagouensis S81
    |--D. yixianensis S81
    `--D. zhoulangensis S81
  Gansulimnadia S81
    |--G. ovata S81
    `--G. quadrata S81
  Pseudestherites qinghemensis S81
  Yanjiestheria S81
    |--Y. fusiformis S81
    |--Y. hanhsiaensis S81
    |--Y. minor S81
    |--Y. sinensis S81
    |--Y. venulosa S81
    `--Y. yumenensis S81
  Neodiestheria S81
    |--N. changmaensis S81
    `--N. dalaziensis S81
  Orthesteriopsis liupanshanensis S81
  Lepidilla Matthew 1886 BB61
    `--*L. anomala Matthew 1886 BB61
  Lepiditta Matthew 1886 BB61
    `--*L. alata Matthew 1886 BB61
  Laxitextella laxitexta (Jones 1890) DS16

*Type species of generic name indicated

REFERENCES

Ax, P. 2000. Muticellular Animals: the phylogenetic system of the Metazoa vol. 2. Springer.

[BB61] Benson, R. H., J. M. Berdan, W. A. van den Bold, T. Hanai, I. Hessland, H. V. Howe, R. V. Kesling, S. A. Levinson, R. A. Reyment, R. C. Moore, H. W. Scott, R. H. Shaver, I. G. Sohn, L. E. Stover, F. M. Swain & P. C. Sylvester-Bradley. 1961. Systematic descriptions. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt Q. Arthropoda 3: Crustacea: Ostracoda pp. Q99–Q421. Geological Society of America and University of Kansas Press.

[BWW93] Briggs, D. E. G., M. J. Weedon & M. A. Whyte. 1993. Arthropoda (Crustacea excluding Ostracoda). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 321–342. Chapman & Hall: London.

[D01] Daday, E. 1901. Édesvizi mikroszkópi állatok [Mikroskopische Süsswasserthiere]. In: Horváth, G. (ed.) Zichy Jenő Gróf Harmadik Ázsiai Utazása [Dritte Asiatische Forschungsreise des Grafen Eugen Zichy] vol. 2. Zichy Jenő Gróf Harmadik Ázsiai Utazásának Állattani Eredményei [Zoologische Ergebnisse der Dritten Asiatischen Forschungsreise des Grafen Eugen Zichy] pp. 375–470. Victor Hornyánszky: Budapest, and Karl W. Hierseman: Leipzig.

[DS16] Dzik, J., & T. Sulej. 2016. An early Late Triassic long-necked reptile with a bony pectoral shield and gracile appendages. Acta Palaeontologica Polonica 61 (4): 805–823.

[G20] Goldfuss, G. A. 1820. Handbuch der Naturgeschichte vol. 3. Handbuch der Zoologie pt 1. Johann Leonhard Schrag: Nürnberg.

[L02] Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 4. Familles naturelles des genres. F. Dufart: Paris.

[LSE13] Legg, D. A., M. D. Sutton & G. D. Edgecombe. 2013. Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nature Communications 4 (2485): 1–7.

[RS10] Regier, J. C., J. W. Shultz, A. Zwick, A. Hussey, B. Ball, R. Wetzer, J. W. Martin & C. W. Cunningham. 2010. Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences. Nature 463: 1079–1083.

[S81] Shen Y.-B. 1981. Fossil conchostracans from the Chijinpu Formation (Upper Jurassic) and the Xinminpu group (Lower Cretaceous) in Hexi Corridor, Gansu. Acta Palaeontologica Sinica 20 (3): 266–272.

[S02] Sinitshenkova, N. D. 2002. Ecological history of the aquatic insects. In: Rasnitsyn, A. P., & D. L. J. Quicke (eds) History of Insects pp. 388–426. Kluwer Academic Publishers: Dordrecht.

[T06] Timms, B. V. 2006. The large branchiopods (Crustacea: Branchiopoda) of gnammas (rock holes) in Australia. Journal of the Royal Society of Western Australia 89 (4): 163–173.

Last updated: 22 October 2020.