Cryptocandona tsukagoshii, Smith, Robin J., 2011

Smith, Robin J., 2011, Groundwater, spring and interstitial Ostracoda (Crustacea) from Shiga Prefecture, Japan, including descriptions of three new species and one new genus, Zootaxa 3140, pp. 15-37 : 24-27

publication ID	https://doi.org/ 10.5281/zenodo.207945
DOI	https://doi.org/10.5281/zenodo.6185469
persistent identifier	https://treatment.plazi.org/id/03EE4061-BE4E-7013-ACAD-E7FFFDAFFCE5
treatment provided by	Plazi
scientific name	Cryptocandona tsukagoshii
status	sp. nov.

Treatment

Cryptocandona tsukagoshii n. sp.

( Figs 5 View FIGURE 5. A – D E–H, 7, 8)

Material examined. Three females and one empty carapace from a hole dug into the riverbank of a tributary of the Yasu River, Tsuchiyama-cho, Koka, Shiga Prefecture N35º 00’ 18.1”, E136º 22’ 26.7”, altitude 608 m, 29 January 2010. All material collected by the author.

Etymology. Named after Akira Tsukagoshi, Shizuoka University.

Type locality. A tributary of the Yasu River, Tsuchiyama-cho, Koka, Shiga Prefecture, N35º 00’ 18.1”, E136º 22’ 26.7”, altitude 608 m.

Type material. Holotype: dissected female ( LBM 1430005081). Paratypes: one dissected female ( LBM 1430005082), one whole carapace ( LBM 1430005083), and one pair of valves ( LBM 1430005084).

Diagnosis. Carapace in lateral view reniform, with equally rounded posterior and anterior margins, maximum height at mid-length and strongly concave ventral margin. Dorsal view very compressed. Calcified inner lamella wide both anteriorly and posteriorly; in postero-ventral region inner lamella with almost straight inner edge and very broad. Fifth limb branchial plate with one ray. Cleaning limb with no e seta, third segment sub-divided, length of h2 approximately 80% that of h1. Sp seta of CR longer than width of ramus at setal attachment point.

Description. Carapace ( Figs 5 View FIGURE 5. A – D E–H, 7A) length 693–728 µm, height 334–367 µm. Lateral view reniform, with dorsal margin evenly curved, posterior and anterior margins equally rounded and ventral margin strongly concave. Maximum height at mid-length. Left valve overlaps right valve along all margins. Marginal fused zone very narrow. Inner calcified lamella wide both anteriorly and posteriorly. In postero-ventral region inner lamella with almost straight inner edge and very broad. Dorsal view very compressed, pointed anteriorly. Surface of valves smooth. Colour translucent white.

Left An1 (of LBM 1430005082) ( Fig. 7 View FIGURE 7 B) with eight segments, the first two of which fused into one large base, with two dorsal setae and two, long sub-apical ventral setae. Third and fourth segments both quadrate and with one apical-dorsal seta each. Fifth segment with one long apical-dorsal seta and one short apical-ventral seta. Sixth segment with two long apical-dorsal setae and one short apical-ventral seta. Seventh segment with three long, one medium length and one short apical setae. Final segment with one long, one-medium length and one short setae, plus aesthetasc y a. Right An1 (of LBM 1430005082) ( Fig. 7 View FIGURE 7 C) with shorter final segment compared with that of left, and with two apical-ventral setae on fifth segment.

An2 ( Figs 7 View FIGURE 7 D, E) with elongate Y aesthetasc. Claw G2 long, approximately 90% length of G1.

Md ( Fig. 7 View FIGURE 7 F, G) alpha and beta setae similar in appearance, both short and slender and of similar length. Gamma seta long. Final segment of palp with wide, claw-like seta accompanied by one long and one short setae on outer edge and two short setae on inner edge.

Mx ( Fig. 7 View FIGURE 7 H) palp two-segmented. First segment with four apical setae. Second segment quadrate with two long and one short setae on outer edge, and three medium-length apical setae on inner edge.

L5 ( Fig. 8 View FIGURE 8 A) branchial plate with one ray, long a, d and b setae. Endite with approximately 14 apical setae. Endopodite relatively short and slender, with three short terminal setae.

L6 ( Fig. 7 View FIGURE 7 I) elongated with long d1 seta on first segment. Setae e and f of equal length and both shorter than proceeding segment. Two g setae, one approximately as long as final segment and one much shorter. Setae h1 and h3 both short. Claw h2 long, slender and curved.

L7 ( Fig. 8 View FIGURE 8 B) four-segmented, with third segment partially divided. First segment with long dp seta and shorter d1 and d2 setae. Second segment with no e seta. Third segment with f seta at partial division. Fourth segment quadrate with h1, h2 and h3 of unequal lengths. Seta h3 longest with h2 approximately 80% of length of h3, and h1 approximately half length of h2.

CR ( Fig. 8 View FIGURE 8 C) with stout ramus and tapering distally, dorsal margin almost straight, ventral margin gently curved. Claws Ga and Gp approximately equal in length. Seta sa short, while seta sp relatively long, exceeding the width of ramus at setal attachment point.

Female genital lobe ( Fig. 8 View FIGURE 8 C) broadly rounded with no projection.

Remarks. No males or evidence of males (i.e. spermatozoa in females) were recovered. The antennules show asymmetry in one specimen (LBM 1430005082), where the final segment of the right is noticeably shorter than that of the left ( Figs 7 View FIGURE 7 B & C), and the fifth segment has an additional apical-dorsal seta. Another specimen does not show this asymmetry in segment lengths and has two apical-dorsal setae on the fifth segments of both antennules.

Several features of C. tsukagoshii n. sp. differ from those of the type species of the genus, Cryptocandona vavrai Kaufmann, 1900 (see re-description in Namiotko et al. 2005): C. vavrai has a short apical-ventral seta on the fourth segment of the antennule (missing in C. tsukagoshii n. sp.), nine setae on the third palp segment of the mandible (seven in C. tsukagoshii n. sp.), four short and one long setae, and a claw-like seta on the final segment of the mandible (one less short seta in C. tsukagoshii n. sp.), two a setae on the fifth limb (one in C. tsukagoshii n. sp.), three rays on the L5 branchial plate (one in C. tsukagoshii n. sp.), and the e seta present on the seventh limb (missing in C. tsukagoshii n. sp.).

The lack of seta e on the second segment, the long h2 seta (approximately 80% the length of h1) of the seventh limb, and the relatively long Sp seta of the caudal ramus (longer than the width of the ramus at its attachment point) are features shared with Cryptocandona pygmaea ( Ekman, 1908) . However, C. pygmaea has a different shaped carapace, with maximum height towards the posterior and a straight ventral margin. In carapace shape the specimens resemble Cryptocandona reducta ( Alm, 1914) , with the maximum height approximately at mid-length and with equally rounded posterior and anterior margins. However, at 680 µm in length, they are notably smaller than C. reducta (which is typically around 900–1020 µm in length), and the calcified inner lamella in the postero-ventral region is noticeably wider. Despite their small size, the presence of large, well-developed eggs in the specimens indicates that they are fully mature adults. Cryptocandona brehmi ( Klie, 1934) , at 830 µm in length, is closer in size to C. tsukagoshii n. sp., but the appendages of C. brehmi are notably different, especially the shorter lengths of the claws on the antenna, the shorter Sp seta on the caudal ramus, the shorter claw on the sixth limb, and the narrower calcified inner lamella of the carapace (see Namiotko & Danielopol 2002).

This species was found in an interstitial sample taken from a very poorly sorted river bar, consisting of cobbles, pebbles, sand and mud, of a tributary of the Yasu River. The river at the type locality is very shallow and fast flowing and is surrounded by woodland.

Genus Fabaeformiscandona Krsti ć