Fabaeformiscandona subacuta ( Yang, 1982 )

Savatenalinton, Sukonthip, 2014, Ostracods (Crustacea: Ostracoda) from the floodplain of the Chi River, Mahasarakham Province, Northeast Thailand, with the first record of male Tanycypris siamensis Savatenalinton & Martens, 2009, Zootaxa 3838 (2), pp. 195-206 : 201

Fabaeformiscandona subacuta ( Yang, 1982)

( Fig. 4 )

This species was described from China as Candona subacuta ( Hou et al., 1982) and several records were subsequently reported from several parts of the world under different names, most of them as F. japonica (see Escrivà et al. 2012). Its distribution was thought to be restricted to the Palaearctic region ( Martens & Savatenalinton 2011). In Asia, it was recorded from Japan, China and South Korea ( Escrivà et al. 2012). The present record is the first one for the Oriental region. This raises intriguing questions about possible dispersal mechanisms, tolerances to a wide range of environmental factors and the resulting biogeographical distribution. The morphology of the Thai specimens is very similar to that of the Japanese specimens, including that of the male reproductive organs ( Smith & Kamiya 2007). Six females and 4 males were found from 2 localities in this study. The species has thus far been found in various habitats ranging from rice fields, man-made ponds, lakes (see Smith & Janz 2008) and small oxbow lakes (present study, number 9 and 15 in Fig. 1 ). The range of environmental variables from the Thai localities was: temperature 28.9–29.6 °C, DO 2.21–2.90 mg /L and pH 6.5–6.9.

Figures

FIGURE 1. Sampled localities in floodplain of the Chi River, Mahasarakham Province, Thailand.

FIGURE 4. Fabaeformiscandona subacuta (Yang, 1982), female (A – D) and male (E – F). A. Left valve, external view. B. Right valve, external view. C. Left valve, internal view. D. Right valve, internal view. E. Left valve, internal view. F. Right valve, internal view. Scale bar: 200 Μm.