Loxoconchinae

Loxoconcha sp., copyright Hecht801.

Belongs within: Cytheroidea.

The Loxoconchinae are a group of ostracods known from shallow marine or brackish waters. In members of the genera Loxoconcha and Cytheromorpha the hinge has a gongylodont dentition with the anterior of the left valve and posterior of the right having a horseshoe-shaped structure or pair of teeth articulating with a single tooth in the opposite valve (Benson et al. 1961).

Characters (from Benson et al. 1961, as Loxoconchidae): Small, usually dimorphous carapaces, which may be nearly smooth but mostly are finely to coarsely pitted or reticulate; reniform to rectangularly ovate in lateral view with tendency to develop a posterior caudal process in some genera. Hinge typically gongylodont; in some species with anterior left and posterior right dentition appearing as two distinct teeth separated by deep pit but with these teeth normally united above by narrow crescentic ridge that makes horseshoe-shaped structure fitting over single tooth in opposite valve; marginal areas broad, tending to develop vestibules at ends; radial canals few, normal canals widely spaced, large, and in some genera sieve-like; adductor scars in slightly oblique row of four elongate spots (divided in some), antennal scar U- or C-shaped, mandibular scars two oval spots obliquely below and forward.

<==Loxoconchinae [Cytheromorphinae]
    |--Loxoconchella Triebel 1954 M61, BB61
    |    `--*L. honoluliensis (Brady 1880) [=Loxoconcha honoluliensis] BB61
    |--Loxoella Kuznetsova 1956 M61
    |    `--*L. inviolata Kuznetsova 1956 M61
    |--Pseudoloxoconcha Müller 1894 M61, BB61
    |    `--*P. minima Müller 1894 BB61
    |--Cytheromorpha Hirschmann 1909 NT02
    |    |--C. fuscata (Brady 1869) [=Cythere fuscata; incl. *Cytheromorpha albula Hirschmann 1909] BB61
    |    `--C. acupunctata (Brady 1880) [=Cythere acupunctata] NT02
    `--Loxoconcha Sars 1866 NT02 [incl. Loxoleberis Sars 1866 BB61, Normania Brady 1866 non Bowerbank 1869 BB61]
         |--L. rhomboidea (Fischer 1855) (see below for synonymy) BB61
         |--L. curryi BB61
         |--L. grateloupriana BB61
         |--L. helgolandica Klie 1929 DH86
         |--L. kosugii Nakao & Tsukagoshi 2002 NT02
         |--L. lenticulata LeRoy 1943 S-VC91
         |--L. lenticuloides (Swain & Gilby 1974) G83
         |--L. matagordensis BB61
         |--L. nana Marinov 1962 DH86
         |--L. pulchra Ishizaki 1968 NT02
         |--L. subtriangularis S61
         `--L. uranouchiensis Ishizaki 1968 NT02

Loxoconcha rhomboidea (Fischer 1855) [=Cythere rhomboidea; incl. C. impressa Baird 1850 non M’Coy 1844, *Loxoconcha impressa] BB61

*Type species of generic name indicated

REFERENCES

[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.

[DH86] Danielopol, D. L., & G. Hartmann. 1986. Ostracoda. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 265–294. E. J. Brill/Dr W. Backhuys: Leiden.

[G83] Gottwald, J. 1983. Interstitielle Fauna von Galapagos. XXX. Podocopida 1 (Ostracoda). Mikrofauna des Meeresbodens 90: 1–187.

[M61] Moore, R. C. 1961. Supplement—USSR treatise on Ostracoda. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt Q. Arthropoda 3: Crustacea: Ostracoda pp. Q422–Q429. Geological Society of America and University of Kansas Press.

[NT02] Nakao, Y., & A. Tsukagoshi. 2002. Brackish-water Ostracoda (Crustacea) from the Obitsu River estuary, central Japan. Species Diversity 7 (1): 67–115.

[S61] Scott, H. W. 1961. Shell morphology of Ostracoda. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt Q. Arthropoda 3: Crustacea: Ostracoda pp. Q21–Q37. Geological Society of America and University of Kansas Press.

[S-VC91] Segura-Vernis, L. R., & A. L. Carreño. 1991. Foraminíferos y ostrácodos de la Laguna de La Paz, Baja California Sur, México. Inv. Mar. CICIMAR 6 (1): 195–224.

Last updated: 11 October 2020.