OSTRACOD RESEARCH

at the Lake Biwa Museum, Japan


Robin James Smith

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Genus Fabaeformiscandona Krstic, 1972

Superfamily: Cypridoidea Baird, 1845
Family: Candonidae Kaufmann, 1900
Subfamily: Candoninae Kaufmann, 1900

Thirteen species have been reported from Japan:

1. Fabaeformiscandona akaina Smith & Janz, 2008


Left side view of a male Fabaeformiscandona akaina, length 1.3 mm.



Left side view of a female Fabaeformiscandona akaina, length 1.3 mm.



External view of a female left valve of Fabaeformiscandona akaina, length 1315 microns.



The male sexual organ of Fabaeformiscandona akaina, length 596 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


2. Fabaeformiscandona condylea Smith & Janz, 2008


Right side view of a male Fabaeformiscandona condylea, length 0.6 mm.



External view of a male left valve of Fabaeformiscandona condylea, length 640 microns.



External view of a female left valve of Fabaeformiscandona condylea, length 588 microns.



The male sexual organ of Fabaeformiscandona condylea, length 190 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic and interstitial.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008) and rivers flowing into Lake Biwa (Smith 2011).

References:
Smith, R. J. 2011. Groundwater, spring and interstitial Ostracoda (Crustacea) from Shiga Prefecture, Japan, including descriptions of three new species and one new genus. Zootaxa, 3140, 15-37.

Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865-2922.


3. Fabaeformiscandona dolabella Smith & Janz, 2008


Left side view of a female Fabaeformiscandona dolabella, length 0.9 mm.



External view of a male left valve of Fabaeformiscandona dolabella, length 980 microns.



The male sexual organ of Fabaeformiscandona dolabella, length 361 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


4. Fabaeformiscandona kushiroensis Hiruta & Hiruta 2015

Figures in: Hiruta & Hiruta 2015 (carapace and appendages).
Habitat: Spring in a marsh.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Kushiro Marsh, Kushiro Shitsugen National Park, eastern Hokkaido, Japan.

References:
Hiruta, S. F. & Hiruta, S. 2015. Description of a species of Fabaeformiscandona (Ostracoda, Crustacea) from Kushiro Marsh, Hokkaido, Japan, with the nearly complete mitochondrial genomic sequence. Biodiversity Data Journal, 3, e7074, 1-30. doi: 10.3897/BDJ.3.e7074.


5. Fabaeformiscandona myllaina Smith & Kamiya, 2006


Left side view of a male of Fabaeformiscandona myllaina, length 1.2 mm.



Left side view of a female of Fabaeformiscandona myllaina, length 1.1 mm.



External view of a male left valve of Fabaeformiscandona myllaina, length 1255 microns.



External view of a female left valve of Fabaeformiscandona myllaina, length 1070 microns.



The male sexual organ of Fabaeformiscandona myllaina, length 577 microns.


Additional figures in: Smith & Kamiya 2007 (carapace and appendages), Smith & Janz 2008 (carapace and appendages), Zhai & Zhao 2014 (carapace and appendages).
Habitat: Lake Biwa and ponds.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Kanazawa, Ishikawa Prefecture (Smith & Kamiya 2007), Lake Biwa (Smith & Janz 2008). Elsewhere, Beijing, China (Zhai & Zhao 2014).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.

Smith, R. J. & Kamiya, T. 2007. Copulatory behaviour and sexual morphology of three Fabaeformiscandona Krstic, 1972 (Candoninae, Ostracoda, Crustacea) species from Japan, including descriptions of two new species. Hydrobiologia, 585, 225 - 248.

Zhai, D. & Zhao, W. 2014. On some recent non-marine ostracods from northern China, with description of one new species. Crustaceana, 87, 985-1026.


6. Fabaeformiscandona nishinoae Smith & Janz, 2008


Left side views of a male (top) and female of Fabaeformiscandona nishinoae. Length approximately 1 mm.



External view of a male left valve of Fabaeformiscandona nishinoae, length 1147 microns.



External view of a female left valve of Fabaeformiscandona nishinoae, length 1049 microns.



The male sexual organ of Fabaeformiscandona nishinoae, length 481 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


7. Fabaeformiscandona okuboi Smith & Janz, 2008


Left side views of a male (top) and female of Fabaeformiscandona okuboi, length 0.8 mm.



External view of a male left valve of Fabaeformiscandona okuboi, length 820 microns.



The male sexual organ of Fabaeformiscandona okuboi, length 460 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


8. Fabaeformiscandona paterea Smith & Janz, 2008

Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


9. Fabaeformiscandona pedana Smith & Janz, 2008

Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


10. Fabaeformiscandona subacuta (Yang, 1982)


Left side view of a male Fabaeformiscandona subacuta, length about 1 mm.


Left side view of a female Fabaeformiscandona subacuta, length about 1 mm.


External view of a male left valve of Fabaeformiscandona subacuta, length 1073 microns.


External view of a female left valve of Fabaeformiscandona subacuta, length 980 microns.


The male sexual organ of Fabaeformiscandona subacuta, length 420 microns.


Additional figures in: Smith & Kamiya, 2007 (Carapace and appendages, as Fabaeformiscandona japonica) ; Smith & Janz, 2008 (Carapace and appendages, as Fabaeformiscandona japonica); Chang et al., 2012 (Carapace and appendages, as Fabaeformiscandona japonica); Escrivá et al., 2012 (Carapace and appendages).
Habitat: Lakes, ponds, spring runoff, irrigation canals, rice fields.
Mode of life: Benthic
Reproduction mode: Sexual.
Known distribution:Fukuoka, Gunma, Ishikawa, Okayama, Shiga, and Shizuoka Prefectures, Okinawa. Elsewhere, China, Korea, Thailand, Russia, Spain, Australia, New Zealand, Columbia. This species is considered invasive in Spain (Escrivá et al., 2012).

References:
Chang, C. Y., Lee, J. & Smith, R. J. 2012. Nonmarine ostracods (Crustacea) from South Korea, including a description of a new species of Tanycypris Triebel (Cyprididae, Cypricercinae). Zootaxa, 3161, 1 - 19.

Escrivá, A., Smith, R. J., Aguilar-Alberola, J. A., Kamiya, T., Karanovic, I., Rueda, J., Schornikov, E. I. and Mesquita-Joanes, F. 2012. Global distribution of Fabaeformiscandona subacuta: An exotic invasive Ostracoda on the Iberian Peninsula? Journal of Crustacean Biology, 32, 949-961.

Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.

Smith, R. J. & Kamiya, T. 2007. Copulatory behaviour and sexual morphology of three Fabaeformiscandona Krstic, 1972 (Candoninae, Ostracoda, Crustacea) species from Japan, including descriptions of two new species. Hydrobiologia, 585, 225 - 248.



11. Fabaeformiscandona tora Smith & Kamiya, 2007


A male (top) and female of Fabaeformiscandona tora, left side views, length approximately 1 mm.



External view of a male left valve of Fabaeformiscandona tora, length 968 microns.



External view of a female left valve of Fabaeformiscandona tora, length 866 microns.



The male sexual organ of Fabaeformiscandona tora, length 327 microns.


Additional figures in: Smith & Kamiya 2007 (carapace and appendages), Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Kanazawa, Ishikawa Prefecture (Smith & Kamiya 2007), Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Kamiya, T. 2007. Copulatory behaviour and sexual morphology of three Fabaeformiscandona Krstic, 1972 (Candoninae, Ostracoda, Crustacea) species from Japan, including descriptions of two new species. Hydrobiologia, 585, 225 - 248.

Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


12. Fabaeformiscandona velifera Smith & Janz, 2008


External view of a male left valve of Fabaeformiscandona velifera, length 812 microns.



The male sexual organ of Fabaeformiscandona velifera, length 266 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


13. Fabaeformiscandona yajimae Smith & Janz, 2008


External view of a male left valve of Fabaeformiscandona yajimae, length 978 microns.



The male sexual organ of Fabaeformiscandona yajimae, length 297 microns.


Additional figures in: Smith & Janz 2008 (carapace and appendages).
Habitat: Lake Biwa.
Mode of life: Benthic.
Reproduction mode: Sexual.
Known distribution: Currently only known from Lake Biwa (Smith & Janz 2008).

References:
Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865 - 2922.


Key characters Fabaeformiscandona species
Carapace - ventral valve overlapLeft valve overlaps right along ventral margin
Carapace - margin structure - septaNo septa present
Carapace - margin structure - ridges on inner calcified lamellaNo ridges
Carapace - dorsal view - female with brood pouchBrood pouch not visible
Carapace - lateral view - ventral marginVentral margin approximately straight to concave
Carapace - lateral view - valve heightLeft and right valves similar height
Carapace - internal viewAnterior calcified inner lamella wider than posterior one
Carapace - ornamentation - denticlesNo denticles near ventral margin
Carapace - ornamentation - sulcusNo sulcus
Carapace - ornamentation - surfaceSurface smooth
Carapace - width/length ratio (w/l)Less than 0.4 (slender species)
Antennule - segmentsSeven moveable segments
Antennule - Rome organNo Rome organ
Antenna - exopoditeExopodite reduced to small segment
Antenna - swimming setaeNo swimming setae present
Fifth limb - morphologyMaxilliped; Male palps one fused mass
Sixth limb - segmentsFive segments
Sixth limb - setae on first segmentOne seta
Sixth limb - h3 seta on final segmentH3 seta short; much shorter than half length of claw
Seventh LimbCleaning limb, with three setae at end
Seventh Limb - segmentsFive segments
Seventh Limb - first segmentTwo setae
Caudal ramusElongate ramus with two claws and two setae
Caudal ramus - attachmentWith no loops