Four new species of the subfamily Candoninae (Crustacea, Ostracoda) from freshwater habitats in Japan

Abstract

Three species of the genus Pseudocandona Kaufmann, 1900 and one of the genus Undulacandona Smith, 2011, collected from freshwater habitats in Japan, are described. The Pseudocandona species, Pseudocandona becca sp. nov., Pseudocandona atmeta sp. nov. and Pseudocandona falcula sp. nov., all belong to the rostrata-group. Previous reports of Pseudocandona rostrata (Brady & Norman, 1889) and Pseudocandona sarsi (Hartwig, 1899) from Japan are reassessed and are subsequently synonymized with Pseudocandona tenuirostris Hiruta & Mawatari, 2013 and Pseudocandona falcula sp. nov. respectively. Undulacandona colymba sp. nov. is only the second to be described in this genus. Like the type species of the genus, it is a stygobiont, collected from groundwater in Shiga Prefecture. Additional records of Candona candida (O.F. Müller, 1776), are presented herein; so far, Japanese records of this species are restricted to the eastern part of Hokkaido.

<i>Rugosuscandona</i>, a New Genus of Candonidae (Crustacea: Ostracoda) from Groundwater Habitats in Texas, North America

“…We hypothesize that these reductions (i.e., in chaetotaxy) might represent derived adaptations to groundwater ecosystems, but since we do not know fossil forms of the genus yet, general conclusion of its evolutionary history cannot be made at the moment. This is also the case indicated for Undulacandona from Japan by Smith and Kamiya (2015). Up to now, the only fossil form of the tribe is known from the genus Candonopsis from the Miocene (Danielopol 1980).…”

“…According to Karanovic (2012), Marococandona nicolae Marmonier, Boulal and Idbennacer, 2005 has 6-segmented A1, but this seems to be in error as the species was described as having 5 segmented A1 (see Marmonier et al 2005: figs 5A, 7A). Smith (2011) and Smith and Kamiya (2015) described Undulacandona Smith, 2011 with 2 species stating that A1 bears 6 segments where the first 2 segments were partially fused together.…”

“…Species of some genera (e.g., Paracandona) and tribes (e.g., Humphreyscandonini Karanovic, 2005) do not have bristles on the male A2, but mostly bear z-setae. Also, some genera have 2 short setae (e.g., Danielocandona) or 3 short setae (e.g., Trajancandona and Undulacandona) on the exopod (see Karanovic 1999;Smith and Kamiya 2015), while a majority of genera of Candoninae have 2 short and 1 long seta. The absence of an exopod and t-setae are only known in 1 other groundwater genus of the tribe Candonopsini (Külköylüoğlu et al in review).…”

“…Unlike these genera, some other genera (Meischcandona, Namibcypris, Danielocandona, and Trajancandona) in other tribes of the subfamily Candoninae exhibit 3 setae (Karanovic 2001). In Rugosuscandona gen. nov., the terminal segment consists of 3 long claw-like and 2 short smooth setae but other congeners have total 6 on the same segment (e.g., Undulacandona) (Smith and Kamiya 2015). Reduction of the setae may be considered as convergent with those of other species with similar niches (Mayr and Ashlock 1991), but this needs further investigation.…”

Ufocandona hannaleeae gen. et sp. nov. (Crustacea, Ostracoda) from an artesian well in Texas, USA

“…However, given the differences discussed above, the inclusion of this important character state in keys should be considered. Additionally, the absence of t-setae (t1-4) on A2 in Ufocandona gen. nov. is important to consider; these setae are present and of normal size in some members of the Candonidae (e.g., Bicornucandona; Külköylüoğlu et al 2011) and/or transformed into bristles in the males of some other genera (e.g., Candonopsis (Abcandonopsis) Karanovic, 2004;Acandona Karanovic, 2003(Karanovic 2003b, 2007, 2012; Indocandona (Gupta 1984;Karanovic & Ranga Reddy 2008); Undulacandona (Smith & Kamiya 2015)). …”