Loboixys tetramera, Kim & Boxshall, 2020
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publication ID |
https://doi.org/ 10.11646/megataxa.4.1.1 |
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DOI |
https://doi.org/10.5281/zenodo.5728091 |
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persistent identifier |
https://treatment.plazi.org/id/03C487CB-ED4B-382F-FF4D-FEFAFB2FFC39 |
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treatment provided by |
Plazi |
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scientific name |
Loboixys tetramera |
| status |
sp. nov. |
Loboixys tetramera sp. nov.
( Figs. 359 View FIGURE 359 , 360 View FIGURE 360 )
Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21403 ) from Trididemnum cyclops Michaelsen, 1921 , New Caledonia, Récif Néokumbi ext, Stn NC30, depth 20-30m, Monniot coll., 09 March 1987.
| Coxa | Basis | Exopod | Endopod | |
|---|---|---|---|---|
| Leg 1 | 0-0 | 1-1 | 1-0; 1, 1, 3 | 0-1; 1, 2, 2 |
| Leg 2 | 0-0 | 1-0 | 1-0; 1-0; 3, 1, 5 | 0-0; 1, 2, 1 |
| Leg 3 | 0-0 | 1-0 | 1-0; 3, 1, 5 | 0-0; 1, 2, 1 |
| Leg 4 | 0-0 | 1-0 | 1-0; 2, 1, 5 | 0-0; 0, 2, 1 |
| Leg 5 | absent ( Fig. 359C View FIGURE 359 ). | |||
Etymology. The name is derived from the Greek tetr (=four) and mero (=part), alluding to the four-segmented urosome of the new species.
Descriptionoffemale. Body ( Fig. 359A, B View FIGURE 359 ) highly transformed, globular, about 2.0 mm long along body axis. Bodysurface smooth. Prosome curved ventrally; dorsal cephalic shield lacking posterolateral horn-like processes. Metasome 4-segmented; fourth pedigeroussomite nearly spherical, 1.15 mm in dimeter, consisting of narrower dorsal and broad ventral zones indented ventrally. Free urosome ( Fig. 359C View FIGURE 359 ) small, tapering, inserted into indented ventral surface of brood pouch, 4-segmented, consisting of genital and 3 abdominal somites measuring 68×330, 68×227, 50×197, and 105×175 μm, respectively. Caudalramus ( Fig. 359C View FIGURE 359 ) narrowing distally, about 2.3 times longerthan wide (100×47 μm) and slightly shorter than anal somite: armed with 4 small setae only (1 outer lateral and 3 distal).
Rostrum ( Fig. 359D View FIGURE 359 ) bulbous, ornamented with long setules along distal margin. Antennule ( Fig. 359D View FIGURE 359 ) small, tapering, abruptly narrowing in distal third, 85 μm long, unsegmented and apparently unarmed, but ornamented with many setules. Antenna ( Fig. 359E View FIGURE 359 ) 3-segmented; coxa and basis unarmed; unsegmented endopod about 3.7 times longer than wide (63×17 μm) and about 0.8 times as long as basis: armed with 5 small setae (arranged as 1, 2, and 2) plus small terminal claw, about 0.35 times as long as endopod.
Labrum ( Fig. 359F View FIGURE 359 ) with broad, straight posterior margin covered with fine setules. Mandible ( Fig. 359G View FIGURE 359 ) with 6 acute teeth, including smaller distalmost tooth, and 1 smallsetaoncoxalgnathobase; palparmedwith 1 setaon basis, 5 equal setae on exopod, and 5 setae on endopod (1 on first and 4 on second segment). Maxillule ( Fig. 359H View FIGURE 359 ) armed with 6 setae on arthrite, 1 on basis, 4 on exopod and 3 on endopod; coxa lacking endite and epipodite. Maxilla ( Fig. 360A View FIGURE 360 ) 4-segmented, strongly flexed between syncoxa and basis; syncoxa with 4 (including 1 minute seta), 2, and 2 setae on first to third endites, respectively; basis with 2 small setae; first endopodal segment with 1 thick seta, second segment with 1 thick, spiniform seta and 2 small setae. Maxilliped ( Fig. 359I View FIGURE 359 ) as unsegmented lobe bearing 6 setae and scattered fine spinules.
Legs 1–4 ( Fig. 360 View FIGURE 360 B-E) biramous: protopod 2- segmented in legs 1–3, unsegmented and obscurely defined at base in leg 4. Inner coxal seta absent in legs 1–4. Endopods of these legs 2–segmented, shorter than exopods. Exopods of legs 1–3 incompletely segmented. Leg 4 with distinctly 2-segmented rami; endopod much reduced in size. All setae naked and short. Armature formula for legs 1–4 as follows:
Male. Unknown.
Remarks. Loboixys tetramera sp. nov. is unique within the genus in having a 4-segmented urosome and in lacking leg 5. Additional diagnostic features include: the antennule is small, unsegmented, andornamented only with setules, without identifiable setae, the coxal gnathobase of the mandible is armed with 6 teeth, and the swimming legs are armed with the fewest setae of any species within the genus, i.e., the endopods of legs 1–4 carry 6, 4, 4, and 3 setae, respectively. These features allow us to differentiate L. tetramera sp. nov. from its congeners.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.