Notodromas trulla, Smith, Robin J. & Kamiya, Takahiro, 2014

Smith, Robin J. & Kamiya, Takahiro, 2014, The freshwater ostracod (Crustacea) genus Notodromas Lilljeborg, 1853 (Notodromadidae) from Japan; taxonomy, ecology and lifestyle, Zootaxa 3841 (2), pp. 239-256 : 245-246

Comparisons between Notodromas trulla n. sp. and other Notodromas species

Notodromas monacha ( O. F. Müller, 1776) —This is the type species of the genus, and found in Western Europe (see review of its Western European distribution in Meisch 2000), Eastern Europe, European part of Russia, southern to northern Caucasus, western Siberia, Kazakhstan and Altai ( Bronshtein 1947), Central Asia ( Sars 1903), China (Chen 1982) ( Fig. 1A ), USA ( Sharpe 1908), and Canada ( Delorme 1970). The carapaces of both males and females of N. monacha are generally very similar to Notodromas trulla n. sp., with the exception of the females' postero-ventral flange ( Figs 2 C, D, & H). In N. monacha the females' flange on the left valve overlaps the right ( Fig. 3 G), while in Notodromas trulla n. sp. the flange on the right valve overlaps the left ( Fig. 3F ).

Notodromas monacha also has a noticeably shorter aesthetasc Y on the antennae compared to Notodromas trulla n. sp., and instead of the spoon-shaped seta on the males' fifth limb right palp, which is a characteristic feature of Notodromas trulla n. sp., has an apical seta ( Fig. 7 H, marked with black triangle). The claws of the caudal ramus are sub-equal in length in Notodromas trulla n. sp., whereas the claw Gp is typically shorter than Ga in N. monacha (e.g. Sywula 1974; Meisch 2000) ( Fig. 7 J). Additionally, the distal section of the caudal ramus of N. monacha is noticeably more slender than that of Notodromas trulla n. sp. The most significant difference, however, is the shape and structure of the hemipenes ( Figs 7 K, 8B). Those of N. monacha are larger, and wider distally, with a distinctive lobe on the inner edge ( Fig. 7 K, marked with black triangle). The hemipenes of Notodromas trulla n. sp. are more sub-rectangular, and with no lobe on the inner edge. The internal structures of the two species' hemipenes are sufficiently different to make homologies of some parts difficult; Notodromas trulla n. sp. has two internal, rounded lobe-like structures ( Fig. 7G, labelled as 'a' and 'b') that are not present in N. monacha , while N. monacha has some internal projections that appear absent in Notodromas trulla n. sp. ( Fig. 7 K, labelled as 'c' and 'd').

Notodromas sinensis Neale & Zhao, 1991 —This species was described from specimens collected from a lake in Heilongjiang, Northeast China, and has also been recovered from other localities in China and the far east of Russia ( Zhao 1990; Schornikov & Trebukhova 2001; Schornikov 2004; Zenina & Schornikov 2008) ( Fig. 1A ). It closely resembles N. monacha , differing in the morphology of the caudal ramus attachment, male fifth limb palps, details of the hemipenes, and by having a “more robust” sixth limb ( Neale & Zhao, 1991). The carapaces of N. sinensis and N. monacha are very similar, with only the female posterior flange a slightly different shape in ventral view, indicating that perhaps these species are the most closely related in the genus. Differences between Notodromas trulla n. sp. and N. sinensis are therefore similar to those between Notodromas trulla n. sp. and N. monacha (see above).

Notodromas persica Gurney, 1916 — With a distribution in Iran ( Löffler 1961; Bronshtein 1947), Western Europe and the circum-Mediterranean region ( Gauthier 1928; Meisch 2000), this species is much more restricted in distribution than N. monacha . Meisch (2000) suggested that based on the shape of the projection on the female carapace, the record of N. monacha from Jakutsk, Siberia (Pietrzeniuk 1977) was a misidentification of N. persica . The figure provided by Pietrzeniuk (1977) of a female adult specimen does resemble N. persica , but as Pietrzeniuk (op. cit.) reported only one juvenile (p. 334), it is not clear if the adult specimen figured by her came from Jakutsk. As features for species determination only appear in the adult stage, a single juvenile cannot be identified to species level, and this record should therefore be placed in open nomenclature. The carapaces of both sexes of N. persica are similar to those Notodromas trulla n. sp., although they are slightly less elongate ( Figs 2 E & F) and the posterior flange of the female is different in shape ( Figs 2 I & 3H). The aesthetasc Y of the antenna is proportionally shorter in length to that of Notodromas trulla n. sp. and thus similar to that of Notodromas monacha . The right male fifth limb palp of N. persica has a proportionally longer apical clasping hook compared with Notodromas trulla n. sp., and has a tiny apical seta near the base of the hook ( Fig. 7 L, marked with black triangle); this contrasts with the much longer spoon-shaped sub-apical seta found in Notodromas trulla n. sp. The caudal ramus of the male is more strongly curved and the seta sp is longer than in Notodromas trulla n. sp. ( Fig. 7 N). The hemipenes of N. persica are smaller than both N. monacha and Notodromas trulla n. sp., and internally they appear to be the most simple, with neither of the two internal lobes seen in Notodromas trulla n. sp. ( Figs 7 O & 8C).

Notodromas oculata Sars, 1903 —This species was described from two female specimens reared from mud collected in Sumatra, and later this species was reported from Taiwan ( Klie 1938) and Sri Lanka ( Neale 1984) ( Fig. 1A ). Published figures of this species are restricted to the female carapace and caudal ramus, and it differs from Notodromas trulla n. sp. in the following: the carapace is smaller, ranging from 0.59 to 0.75 mm, more elongate (h/ l = 0.62), and it lacks any posterior-ventral projection.

Notodromas serrata Deb, 1984 —This species was described from specimens collected from India ( Deb 1984) ( Fig. 1A ), and has not been reported since. The rudimentary nature of the initial description denies a detailed comparison with other Notodromas species, and George & Martens (2003) questioned its placement in the genus.

Figures

FIGURE 1. A. Map of localities where Notodromas has been reported in eastern Asia. Data from Brehm (1923; 1933); Chen (1982); Deb (1984); Klie (1938); Martens (1991); Mischke et al. (2002); Neale (1984); Neale & Zhao (1991); Okubo & Ida (1989); Okubo (2003); Pietrzeniuk (1977); Sars (1903); Schornikov (2004); Schornikov (1995); Zenina & Schornikov (2008); Zhao (1990). * 1: Reported as N. monacha by Schornikov (1995), but considered to be N. sinensis by Schornikov & Trebukhova (2001). * 2: Reported as N. monacha, but because only one juvenile was recovered (Pietrzeniuk 1977), it is considered to be in open nomenclature herein; see text for more details. * 3: Bronshtein (1947) reported N. monacha from Kazakhstan, but as no specific localities were given, point is approximate. * 4: Sub-fossil occurrence (Mischke et al. 2002). * 5: Sars (1903) raised specimens of N. oculata from mud collected from Sumatra, but didn't specify which of two possibly localities the mud was collected from. Point is therefore approximate. N. B. Bronshtein (1947) reported N. monacha from “ Western Siberia ”, but no specific localities were provided. All Japanese records of N. monacha are considered to be Notodromas trulla n. sp. herein. B. Localities where Notodromas trulla n. sp. has been collected. Numbers correspond to those in Table 1. Locality 3 is approximate, as no specific locality data was given. Note that some older records did not give any locality data.

FIGURE 2. A & B, Notodromas trulla n. sp. A, left lateral view of male carapace (LBM 1430005758). B, left lateral view of female carapace (LBM 1430005753). C & D, Notodromas monacha. C, left lateral view of male carapace. D, left lateral view of female carapace. E & F, Notodromas persica. E, left lateral view of male carapace. F, left lateral view of female carapace. G, Notodromas trulla n. sp., left lateral view of posterior region of female carapace (LBM 1430005754). H, Notodromas monacha, left lateral view of posterior region of female carapace. I, Notodromas persica, left lateral view of posterior region of female carapace. Scale bar = 303 µm for A – F, 70 µm for G – I.

FIGURE 3. A – F. Notodromas trulla n. sp. A, dorsal view of male, anterior to left (LBM 1430005757). B, dorsal view of female, anterior to left (LBM 1430005754). C, oblique ventral view of famale, anterior to right (LBM 1430005756). D, ventral view of female, anterior to left (LBM 1430005756). E, lateral left view of female anterior margin (LBM 1430005756). F, ventral view of female, detail of posterior region, anterior to left (LBM 1430005755). G, Notodromas monacha, ventral view of female, detail of posterior region, anterior to left. H, Notodromas persica, ventral view of female, detail of posterior region, anterior to left. Scale bar = 303 µm for A – D, 70 µm for E – H.