Fabaeformiscandona velifera, Smith & Janz, 2008

Smith, Robin J. & Janz, Horst, 2008, Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan, Journal of Natural History 42 (45 - 46), pp. 2865-2922 : 2879-2881

Fabaeformiscandona velifera sp. nov.

( Figures 8 A–C, 9 and 10)

Type locality

Lake Biwa – eastern shore of southern part of north basin, locality 59 (35 ° 09952.00N; 136 ° 03944.20E) depth 0.2 m, substrate boulders, cobbles and coarse angular sand along a rocky shore.

Type material

Holotype LBM 1430003298 , male, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Allotype LBM 1430003357 , female, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Paratype LBM 1430003297 , male, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Paratype LBM 1430003295 , male, whole carapace stored in a micropalaeontological cavity slide . Paratype LBM 1430003296 , female, whole carapace stored in a micropalaeontological cavity slide .

Derivation of name

From the Latin velifer (neutral) meaning sail-bearing, as the a lobe of the hemipene looks reminiscent of a boat’s sail ( Figure 10B ).

Diagnosis

Carapace with distinctive dorsal hump on posterior third, more developed in male than female. Posterior margin more tightly curved than anterior margin. FRO projection small and stubby. UR only slightly curved. Male L5 palps asymmetrical, left one terminating with long, finger-like process, right one more inflated and hookshaped. Hp with triangular a lobe and m process with inflated distal end.

Description

Male carapace length 772–800 Mm, height 383–400 Mm, H/L50.48–0.5, female length 688–719 Mm, height 328–339 Mm, H/L50.47–0.48. Male carapace with distinctive dorsal hump, maximum height at posterior third. Ventral margin slightly concave. Anterior margin more tightly rounded than posterior margin. Female with less distinct dorsal hump, and tighter curved posterior margin compared with male. Female left valve with well-developed flap on posterodorsal margin, and smaller flap on anterodorsal margin. Dorsal view of female with maximum width at mid-length, anterior margin very slightly beak-shaped. In both sexes, inner calcified lamella wide anteriorly, very narrow posteriorly, slightly wider at posteroventral margin. Surface of valves smooth, colour translucent white.

An1 with eight segments, first two of which are fused together forming one large movable article, supporting two setae on dorsal edge and two long ventral–apical setae. Third segment wider than long with seta on dorsal–apical corner. Fourth segment quadrate with dorsal–apical seta. Fifth and sixth segments each with two long dorsal–apical setae and one short ventral–apical seta. Seventh segment with three long and one short apical setae. Eighth segment with two long setae, one short, stout seta and aesthetasc ya.

An2 with long and very slender Y aesthetasc. Male with relatively long Gm claw, about two-thirds the length of GM, t2 and t3 with triangular ends. Female with G2 claw just over half the length of claw G1. Claw Gm, slightly shorter than GM.

Md with 3+1+beta setae on second segment of palp.

L5 with asymmetrical male palps, right more inflated than left, both drawn out distally to long pointed extremity. Left one with finger-like distal process, right one more inflated and hook-shaped.

L6 claw h2 approximately same length as second segment. Setae e, f and g all as long as, or slightly longer than next segment respectively.

L7 five-segmented with long dp and g seta and short h1 seta.

UR slightly curved with inflated base, claws Ga and Gp relatively short, Ga shorter than Gp.

Hp with large, sub-triangular a lobe, m process with inflated end, angular on inner edge, h lobe large and rounded.

FRO rounded and FRO projection small and stubby, tapering distally.

Remarks

This species comes close to Fabaeformiscandona wegelini (Petkovski, 1962) , of which males are unknown, in the carapace shape of the female and the slightly curved UR. However, it differs in that the L6 of F. wegelini has only very short e, f and g setae (much longer in F. velifera sp. nov.), the h1 seta of the L7 is much longer in F. wegelini and F. wegelini has an Md palp with 4+1+beta setae on the second segment, whereas the Md of F. velifera sp. nov. has 3+1+beta, indicating that they belong to different groups. Another similar species is Fabaeformiscandona tricicatricosa (Diebel and Pietrzeniuk, 1969) in the carapace shape of the females. However, F. tricicatricosa is much larger (1.15–1.25 mm) than F. velifera sp. nov., the fused zone of the carapace is wider and the anterior inner calcified lamella is narrower in F. tricicatricosa compared with F. velifera sp. nov. The males and appendages of F. tricicatricosa remain undescribed. Localities 3, 8 and 59 in Figure 1 .

Figures

Figure 1. Location of Lake Biwa and sampling localities.

Figure 8. (A–C) Fabaeformiscandona velifera sp. nov. (A) Male, whole carapace, right lateral view (LBM 1430003295); (B) female, whole carapace, right lateral view (LBM 1430003296); (C) dorsal view of female, anterior to right (LBM 1430003296). (D–F) Fabaeformiscandona condylea sp. nov. (D) Male, whole carapace, right lateral view (LBM 1430003299); (E) female, whole carapace, right lateral view (LBM 1430003300); (F) dorsal view of female, anterior to right (LBM 1430003301). (G–I) Fabaeformiscandona dolabella sp. nov. (G) Male, whole carapace, right lateral view (LBM 1430003307); (H) female, whole carapace, right lateral view

Figure 10. Fabaeformiscandona velifera sp. nov. (A) L7 (LBM 1430003298); (B) Hp (m process shaded grey) (LBM 1430003298); (C) UR and FRO (LBM 1430003357).