Fabaeformiscandona akaina, Smith & Janz, 2008
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publication ID |
https://doi.org/ 10.1080/00222930802361030 |
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persistent identifier |
https://treatment.plazi.org/id/6530807D-EC0C-FF8C-AF8A-FBC1FD81FED0 |
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treatment provided by |
Carolina |
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scientific name |
Fabaeformiscandona akaina |
| status |
sp. nov. |
Fabaeformiscandona akaina sp. nov.
( Figures 17 View Figure 17 H–J, 22 and 23)
Type locality
South-west margin of northern basin of Lake Biwa, locality 54 (35 ° 10932.20N; 135 ° 59947.10E), depth 31.1 m, substrate mud with a little sand and organic detritus.
Type material
Holotype LBM 1430003326 View Materials , male, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Allotype LBM 1430003327 View Materials , female, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide (locality 65) . Paratype LBM 1430003324 View Materials , male, appendages mounted on a glass slide, valves stored in a micropalaeontological cavity slide . Paratype LBM 1430003325 View Materials , female, whole carapace stored in a micropalaeontological cavity slide (locality 52) .
Derivation of name
From the Greek akaina meaning thorn or spine, referring to the spine on the a lobe of the hemipenis ( Figure 23D View Figure 23 ).
Diagnosis
Large species for genus. Carapace with distinctive dorsal hump, posterior margin tightly rounded, with apex below mid-height. Walking leg with very long claw, longer than second segment. Hemipene with spine on a lobe. Projection of FRO very large, female UR strongly curved.
Description
Male carapace length 1364–1393 Mm, height 675–689 Mm, H/L50.49, female length 1252–1294 Mm, height 591–598 Mm, H/L50.46–0.48. Male carapace: dorsal margin curved with maximum height posterior of mid-length. Ventral margin with concavity anterior of mid-length. Posterior margin tightly curved, maximum curvature below mid-height. Anterior margin evenly curved. Dorsal view of females with posterior margin more pointed than anterior margin, maximum width anterior of mid-length. Calcified inner lamella wider anteriorly than posteriorly. Female carapace generally similar to male, but slightly smaller and with more tightly curved posterior margin.
An1 eight-segmented, relatively small and reduced, with relatively short setae. First two segments fused together forming one large article. First segment with one dorsal seta. Second segment with one dorsal seta and two ventral–subapical setae. Third segment with one dorsal–apical seta. Fourth segment with two apical setae. Fifth and sixth segments each with two dorsal–apical setae and one shorter ventralapical seta. Seventh segment with four apical setae. Final segment with three setae of differing lengths and one aesthetasc.
Male An2 with slender and relatively short Y aesthetasc. Male setae t2 and t3 with pointed ends. Claw Gm very short, one-third the length of GM. Female An2 with relatively long G2 claw, approximately half the length of G1, claw Gm over half length of GM.
Md with 4+1+beta setae on second palp segment.
Male palps of L5 asymmetrical, with one more inflated distally than other. Both curved and hook-like with small flange on inner side of distal edge.
L6 elongate with long, slender claw, longer than second segment.
L7 five-segmented. Seta h1 long, over half the length of h2.
Male UR distinctively bent towards distal third. Seta Sp long, claw Gp shorter and more slender than Ga. Female UR strongly curved. Projection of FRO very large and triangular in shape, almost as long as ramus of UR.
Hp very large. Lobe a with rounded distal edge and straighter proximal edge, terminating with small spine. Lobe h rounded and m process well developed, with slender, rounded distal end. Proximal projection well developed.
Remarks
This species is most similar to F. nishinoae sp. nov. in carapace shape and morphologies of the male fifth limbs, hemipenes and the female sexual organs. Compared with F. nishinoae sp. nov. this species is larger, the point of maximum curvature of the carapace posterior margin is lower, the female An2 Gm and G2 claws are much shorter, the h2 claw of the L6 is much longer (distinctly longer than the second segment), the a lobe of the Hp is more inflated, the h lobe is wider distally, and the UR Sp seta is proportionally shorter. Features that both species share are the spine on the a lobe of the Hp, a very similar male fifth limb morphology and very large protrusions from the FRO. The female carapace of Fabaeformiscandona yaguodongcuoensis (Huang et al., 1985) from Tibet is similar to that of F. akaina sp. nov., but the male carapace of the former is much more rounded posteriorly than that of the latter. Unfortunately, the appendages of F. yaguodongcuoensis are unknown.
Fabaeformiscandona akaina sp. nov. was found four times during the survey, at depths ranging from 11.8 to 31 m, all at the southern end of the northern basin. Localities 52, 54, 58 and 62 in Figure 1 View Figure 1 .
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