Ilyocypris salebrosa, Smith, Robin J., Janz, Horst & Okubo, Ichiro, 2011

Smith, Robin J., Janz, Horst & Okubo, Ichiro, 2011, Recent Cyprididae and Ilyocyprididae (Crustacea: Ostracoda) from Lake Biwa, Japan, including a summary of the lake’s ostracod fauna, Zootaxa 2874, pp. 1-37 : 17-20

Ilyocypris salebrosa Stepanaitys, 1960

( Figs 9–11 )

1960 Ilyocypris salebrosa sp. nov. —Stepanaitys: 299–300, plate 1; fig. 1.

1963 Ilyocypris shawneetownensis n. sp. —Staplin: 1165, 1172, 1191, pl. 60, fig. 38 1967 Ilyocypris steegeri n. sp. —Kempf: 133–135, Tafel 2, figs 5–6,

1968 Ilyocypris shawneetownensis Staplin—Bhatia : 467–469, 478, table 1, text-figure 2, pl. 4, fig. 2, pl. 5, 26–28. 1970 Pelocypris alatabulbosa n. sp. —Delorme: 1254, figs 25–33.

1971 Ilyocypris shawneetownensis Staplin—Bhatia & Singh : 214, 217, pl. 1, fig. 15. 2001 Ilyocypris salebrosa Stepanaitys, 1960 —Mischke & Schudack: 12, pl. 1, fig. 7. 2001 Ilyocypris salebrosa Stepanaitys, 1959 —Mischke: 27, 68, 71, 72, 77, 81, 82, 83 & 86, tables 2 & 4, figs 9,

10, 34, 37, 39, 40, pl. 2, figs 18–20, appendix C.

2002 Ilyocypris salebrosa Stepanaitys, 1960 —Bates et al.: 231–232, figs 5a–f. 2004 Ilyocypris salebrosa Stepanaitys, 1960 —Schornikov: 458, pl. 1, fig. 1.

2005 lyocypris salebrosa Stepanaitys, 1959 —Özulug: 114–116, figs 1 & 2.

2005 Ilyocypris decipiens (Masi, 1905) —Rossetti et al.: 291, table 1, figs 4k & l. 2006 Ilyocypris salebrosa —Rossetti et al.: 130, fig. 7.

? 2007 Ilyocypris decipiens (Masi, 1905) —Karan-Žnidaršič & Petrov: 61, figs 2q & r. Synonymy herein. 2009 Ilyocypris salebrosa Stepanaitys, 1960 —Yu et al.: 39.

Juv. 2009 Ilyocypris salebrosa —Mischke et al.: fig. 9: 7.

Description. Carapace length 848–960 µm, height 477–532 µm, H/L = 0.54–0.58. Female carapace, dorsal margin slightly concave, anterior margin more inflated than posterior margin, ventral margin concave at mid-length. Maximum height at anterior quarter. Sulcus at mid-length and each valve with three tubercles, one anterior of sulcus near dorsal margin, one larger tubercle posterior of sulcus near dorsal margin and third tubercle near postero-ventral margin. Surface of valves covered with many, well-defined, small pits and with approximately nine small spines spaced around posterior margin. Dorsal view, anterior and posterior ends bluntly pointed, lateral edges highly irregular due to tubercles. Male carapace slightly more elongate than female’s, with sulcus slightly anterior of mid-length.

An1 ( Fig. 10 A) with eight segments, the first two of which fused to form one large base. All setae on final five segments reduced. First segment with long seta on dorsal edge. Second segment with two long setae on ventral-apical corner. Third segment with long dorsal-apical seta. Fourth segment with thin apical-dorsal seta and thin apicalventral seta. Fifth and sixth segments each with two relatively long apical-dorsal setae and two shorter apical-ventral setae. Seventh segment with three relatively long and one shorter apical setae. Final segment with one apical, claw-like seta, one short thin seta, one relatively long seta and aesthetasc ya.

An2 ( Figs 10 B & C) robust and large, with short Y aesthetasc with broad, rounded end. Natatory setae either reaching to end of claws or slightly shorter. T2-4 setae very short, t1 longer, reaching past end of segment. Female with G1 slightly shorter and thinner than G2 and G3. Gm slightly thinner and 88% of length of GM. Z1 short and thickened, z2-3 short and slender. Male ( Fig 10 D) similar to female with following exceptions: G3 reduced to small claw slightly longer than length of final segment, z1 enlarged to large claw.

Md ( Fig. 10 E & F) palp four-segmented. S2 shorter than s1. Alpha seta very small and slender, beta seta short with setules. Final segment with three robust setae.

Mx ( Fig. 10 G) palp two-segmented, first segment with group of three hirsute setae on outer apical corner, one seta on apical edge and one sub-apical seta. Second segment broad, apically with three robust, equally long setae and two shorter setae.

L5 ( Fig. 11 B) with large endite supporting array of long and short setae along ventral and anterior edge. Female palp reduced and two-segmented terminating with two short setae h1 and h3 and long hirsute seta h2. Male palp ( Fig. 11 A) slightly curved and slender with two sub-apical setae, and terminating with large, elongate, gently curved hook.

L6 ( Fig. 11 C) five-segmented. First segment with seta d1. Setae e and f both shorter than subsequent segment. Seta g small. Fifth segment with relatively long h1 and h3 setae. Claw h2 long and smooth, maximum curvature along distal two-thirds.

L7 ( Fig. 11 D) four-segmented. First segment with long, robust d1 seta. Second segment with e seta shorter than third segment. Third segment with long f and g setae. Final segment elongate with long h1 and h3 setae and with h2 seta approximately half length of h3.

CR ( Fig. 11 E) with curved ramus and long setules on distal half of ventral margin. Claw Ga shorter than Gp.

Hp ( Fig. 11 G) with rounded and stubby a lobe, long, distally expanding h lobe with flattened top and long, curved and pointed b lobe. Zenker organ ( Fig. 11 F) with 18 rows of spines.

Remarks. This is the first report and description of males of this species. Judging from the shape of the carapace and the position of tubercles, specimens figured and recorded as I. decipiens from Serbia ( Karan-Žnidaršič & Petrov 2007) are also probably I. salebrosa .

With the exception of the probable record of I. salebrosa from Serbia, which was noted as consisting of only females ( Karan-Žnidaršič & Petrov 2007), previous records make no mention of the sex of specimens. It is therefore unclear if males are present or absent in populations outside of Lake Biwa.

The specimens found in Lake Biwa were collected from three localities in a small area in the southern part of the northern basin near the outflow of the Hino River, at depths ranging from 5.5 to 16 m. The substrate was muddy, poorly sorted sand, with organic detritus. Only nine live specimens (7 females, 2 males) and three empty carapaces were recovered, suggesting that this species is not abundant in the lake, or that its preferred habitat was not sampled. Localities ( Fig. 1 ): 11, 13, 16.

Figures

FIGURE 1. Location of Lake Biwa and sampling localities that yielded Cyprididae and Ilyocyprididae species.

FIGURE 9. Ilyocypris salebrosa. A—right valve, external view, female (LBM 1430003565). B—right valve, external view, male (LBM 1430003564). C—dorsal view of whole carapace, anterior to right, female (LBM 1430003566). Scale bar = 448 µm.

FIGURE 10. Ilyocypris salebrosa. A—antennule (LBM 1430003567). B—antenna, female (LBM 1430003567). C—detail of female antenna (LBM 1430003567). D—detail of male antenna (LBM 1430003564). E—mandible (LBM 1430003567). Falpha and beta setae of mandible (LBM 1430003567). G—maxillula palp and endites (setae on endites not drawn) (LBM 1430003567).

FIGURE 11. Ilyocypris salebrosa. A—male fifth limb palps (LBM 1430003564). B—female fifth limb (LBM 1430003567). C—sixth limb (LBM 1430003567). D—seventh limb (LBM 1430003567). E—caudal ramus (LBM 1430003567). F—Zenker organ (LBM 1430003564). G—hemipenis (LBM 1430003564).