Fabaeformiscandona yajimae, 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 : 2890-2894

publication ID

https://doi.org/ 10.1080/00222930802361030

persistent identifier

https://treatment.plazi.org/id/6530807D-EC30-FFB8-AFB4-FA4CFC74FE1D

treatment provided by

Carolina

scientific name

Fabaeformiscandona yajimae
status

sp. nov.

Fabaeformiscandona yajimae sp. nov.

( Figures 8 View Figure 8 J–L, 15 and 16)

Fabaeformiscandona fabaeformis: Okubo, 2004 View in CoL (misidentification)

Type locality

Lake Biwa – northern shore of north basin, locality 9 (35 ° 26937.40N; 136 ° 08941.60E) depth 0.1 m, substrate boulders, angular pebbles and gravel.

Type material

Holotype LBM 1430003314 View Materials , male, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Allotype LBM 1430003315 View Materials , female, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Paratype LBM 1430003312 View Materials , male, whole carapace stored in a micropalaeontological cavity slide . Paratype LBM 1430003313 View Materials , female, whole carapace stored in a micropalaeontological cavity slide .

Derivation of name

Named in honour of Dr Michiko Yajima.

Diagnosis

Carapace with dorsal hump posterior of mid-length. Male carapace, anterior and posterior margins almost equally rounded. Female carapace, posterior margin more tightly curved than anterior margin. Female G2 claw of An2 long, approximately 80% length of G1. Male right L5 palp rounded and inflated distally. Male L5 left palp with elongate finger-like projection distally. Posterior projection of FRO elongate and well-developed. Hp m process with large, bulbous distal end, h lobe wide, with long, straight distal edge, a lobe large and angular.

Description

Male carapace length 958–966 Mm, height 503–511 Mm H/L50.52–0.53, female length 861–889 Mm, height 433–442 Mm, H/L50.49–0.52. Male carapace with angular dorsal margin, maximum height just posterior of mid-length. Anterior and posterior margins equally rounded, ventral margin concave. Calcified inner lamella wider anteriorly than posteriorly. Female carapace with more tightly curved posterior margin than male, posterior calcified inner lamella slightly wider along posteroventral margin than posterior margin. Dorsal view of female with slightly beak-shaped posterior and anterior margins, maximum width at midlength. Female left valve with small, but well-defined anterodorsal flap, and welldefined, large posterodorsal flap. Surface of valves smooth, colour translucent white.

An1 small, with eight segments, first two of which fused to produce one large article, with two long setae on dorsal edge and two long setae near apical–ventral corner. Third segment with one dorsal–apical seta. Fourth segment with one apical setae. Fifth and sixth segments each with two dorsal–apical setae and one shorter ventral–apical seta. Seventh segment with two long and two shorter apical setae. Final segment with three setae of differing lengths and one aesthetasc.

An2 with slender medium-length Y aesthetasc. Male t2 and t3 setae with slender, triangular ends. Claw Gm half the length of GM, claw z2 about same length as GM. Female G2 claw approximately 80% length of claw G1, Gm approximately 80% length of GM.

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

L 5 male palps very large and asymmetrical. Right palp very inflated distally with pointed anterior and posterior edges. Left palp with slender, finger-like distal projection.

L6 with elongate and slender second segment. Setae e, f and g all approximately equal in length to next segment respectively. Claw h2 relatively long.

L7 five-segmented. Seta g long, seta h1 relatively short, setae h2 and h3 long and sub-equal in length.

UR, male and female with no significant sexual dimorphism, seta Sp short, claw Gp approximately 75% length of Ga. Ramus with inflated, rounded base and slightly curved distally.

Hp with large striated a lobe with angular distal margin. m process with inflated, bulbous distal end, angular on inner edge. h lobe long with straight edge distally.

FRO sub-rounded with well-developed, finger-like FRO projection with rounded end.

Remarks

In terms of carapace shape in lateral view, this species somewhat resembles Fabaeformiscandona balatonica (Daday, 1894) . However, in dorsal view F. balatonica is much wider than F. yajimae sp. nov. Additionally, the appendages of the two species are quite different, particularly the male fifth limbs and the hemipenes. Furthermore, with 5+1+beta setae on the second segment of the mandibular palp, F. balatonica belongs to a different group (the balatonica group) to that of F. yajimae sp. nov., which has 3+1+beta setae. This species was only found at three localities down to 6 m along the northern shore of the north basin. Localities 7, 8 and 9 in Figure 1 View Figure 1 .

Kingdom

Animalia

Phylum

Arthropoda

Class

Ostracoda

Order

Podocopida

Family

Candonidae

Genus

Fabaeformiscandona

Loc

Fabaeformiscandona yajimae

Smith, Robin J. & Janz, Horst 2008
2008
Loc

Fabaeformiscandona fabaeformis

: Okubo 2004
2004
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