Order BATHYNELLACEA Chappuis, 1915
Compiler and date details
Gary C.B. Poore & Helen M. Lew Ton
Introduction
Bathynellaceans are small interstitial crustaceans. Most are from ground water, a few are from sediments in lakes, and members of one genus are found in interstitial beach sands from low salinity to fully saline. They have a vermiform shape, no eyes and simple appendages typical of many interstitial forms; the largest species is 3.4 mm long. The method of reproduction is uncertain but the female lays 1 or 2 large eggs.
The group occurs worldwide. Most of the early literature of the Bathynellacea is written in German but Schminke (1982) and Schram (1986) have provided diagnoses and discussions of biology. The diagnosis here uses these and also that of Coineau (1996). Schminke (1973) recognised two families, both recorded from Australia. He also discussed at length the evolution and biogeography of the Parabathynellidae in particular. About 150 species are known and were listed by Schminke (1986). Coineau (1996) and Lopretto & Morrone (1998) listed 52 genera, all extant.
Diagnosis
Thoracomere 1 free from cephalon. Pleonites 1-5 separate; pleonite 6 fused to telson; pleotelson with furca. Eyes absent. Antenna 1 inner flagellum minute, with 3 setae. Antennal statocysts absent. Mandibles symmetrical, left incisor fused to an accessory process. Paragnaths present or absent. Thoracopods 1-7 with endopod up to 4-articled, with exopod; thoracopod 8 transformed as copulatory organ in male, more or less reduced in female; epipods present on thoracopods 1-5 or 1-6. Seminal receptacle absent in female. Pleopods 1 and 2 often present, of male not forming a petasma. Uropods not forming a tailfan with telson. Without spermatophores. Seminal receptacle present in female.
References
Chappuis, P.-A. 1915. Bathynella natans und ihre Stellung im System. Zoologische Jahrbucher. Abteilung für Systematik 40: 147–176
Coineau, N. 1996. Sous-classe des Eumalacostracés (Eumalacostraca Grobben, 1892) Super-ordre des syncarides (Syncarida Packard, 1885). pp. 897–954 in Forest, J. (ed.). Traité de Zoologie sous la direction de P.-P. Grassé. Tom. 7 Fasc. 2. Généralités (suite) et systématique (céphalocarides à syncarides). Paris : Masson éditeur pp. 1002
Lopretto, E.C. & Morrone, J.J. 1998. Anaspidacea, Bathynellacea (Crustacea, Syncarida), generalised tracks, and the biogeographical relationships of South America. Zoologica Scripta 27: 311–318
Schminke, H.K. 1973. Evolution, System und Verbreitungs geschichte der Familie Parabathynellidae (Bathynellacea, Malacostraca). Mikrofauna des Meeresbodens 24: 1–192
Schminke, H.K. 1982. Syncarida. pp. 233–237 in Parker, S.P. (ed.). Synopsis and classification of living organisms. New York : McGraw-Hill Vol. 2
Schram, F.R. 1986. Crustacea. New York : Oxford University Press pp. xii 606