Schizoproctus frigidus, Kim & Boxshall, 2021
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publication ID |
https://doi.org/ 10.11646/zootaxa.4978.1.1 |
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publication LSID |
lsid:zoobank.org:pub:9C7C1723-73EB-4FBE-A47A-54627DEB8F93 |
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DOI |
https://doi.org/10.5281/zenodo.5047119 |
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persistent identifier |
https://treatment.plazi.org/id/3729879B-FF97-FF82-FA93-FD09D0B41DA7 |
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treatment provided by |
Plazi |
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scientific name |
Schizoproctus frigidus |
| status |
sp. nov. |
Schizoproctus frigidus sp. nov.
( Figs. 73 View FIG , 74 View FIG )
Type material. Holotype ♀ (MNHN-IU-2018-1980, dissected and mounted on a slide) from Cçrella antarctẚca Sluiter, 1905; Antarctic Ocean, Eltanin cruise 12, Stn 1078 (61°26´S, 41°55.4´W), depth 604 m, 12 April 1964.
Etymology. The specific name is derived from the Latin frẚg (cold), referring to its discovery in Antarctic waters.
Description of female. Body ( Fig. 73A View FIG ) robust, 2.88 mm long. Anterior part of body unsegmented and inflated; cephalosome defined from metasome by faint dorsal constriction. Posterior part of body ( Fig. 73B View FIG ) consisting of genital somite and 4-segmented abdomen. Genital somite much wider than long (205×487 μm) incompletely ar- ticulated from first abdominal somite. First and second abdominal somites 354×436 and 230×385 μm, respectively; third and fourth abdominal somites indistinctly articulated from each other, 128×297 and 210×270 μm, respectively. Caudal ramus ( Fig. 73C View FIG ) about 107×135 μm, armed with 4 claws and 2 setae; lengths of claws 58, 76, 50, and 25 μm from inner to outer.
Rostrum ( Fig. 73D View FIG ) broad, steeply tapering towards nipple-shaped, semicircular apex. Antennule ( Fig. 73E View FIG ) 252 μm long and indistinctly 5-segmented; first segment broad, forming right angle with distal 4 segments; 2 distal articulations incomplete; armature formula 11, 6, 3, 2, and 8+aesthetasc. Left antenna ( Fig. 73F View FIG ) consisting of unarmed coxa, basis and unsegmented endopod; endopod 163× 65 μm, armed with 8 short setae and with rudimentary suture line subdistally defining proximal 3-setae part and distal 5-setae part; longest distal seta 96 μm. Right an- tenna segmented and armed as left antenna; endopod ( Fig. 73G View FIG ) 167×65 μm, subdivided by subdistal sclerotization band.
Labrum ( Fig. 73H View FIG ) much broader than long, with large, soft posteromedian protuberance. Mandible ( Fig. 73I View FIG ) as usual for genus, with 3 teeth on coxal gnathobase and 9 setae on palp. Maxillule ( Fig. 73J View FIG ) with 8 setae on arthrite, distal seta rudimentary; palp unsegmented with vestigial seta representing epipodite, 2 setae on medial margin, 3 setae on outer margin, 1 tubercle distally, and 3 setae on endopod; endopod fused with basis. Maxilla ( Fig. 74A View FIG ) 2-segmented with 2 setae on first segment and 7 setae on second. Maxilliped ( Fig. 74B View FIG ) robust, 4-segmented, but second endopodal segment completely fused with terminal claw; syncoxa broadening distally; basis much wider than long, bearing 2 setae; first endopodal segment unarmed; second endopodal segment + terminal claw complex unarmed, with 1 minute papilla at proximal third.
Legs 1-4 biramous with 1-segmented rami; coxa unarmed; basis with small outer seta. Legs 1 ( Fig. 74C View FIG ) and 2 with same armature. Legs 3 ( Fig. 74D View FIG ) and 4 also with same armature. Outer spines on exopods gradually becoming longer from proximal to distal; longest distal spine shorter than width of exopodal segment. Endopods distinctly tapering. Two anterior (ventral) setae on endopod of legs 3 and 4 naked. Armature formula for legs 1-4 as follows:
| Coxa | Basis | Exopod | Endopod | |
|---|---|---|---|---|
| Legs 1 & 2 | 0-0 | 1-0 | VII | 8 |
| Legs 3 & 4 | 0-0 | 1-0 | VII | 7 |
Leg 5 ( Fig. 74E View FIG ) circular, fleshy, lamellate, 100×92 μm, with 1 rudimentary seta distally. Leg 6 ( Fig. 73K View FIG ) repre- sented by 2 small spinules and 1 spiniform process on genital operculum.
Male. Unknown.
Remarks. The most distinctive diagnostic feature of S. frẚgẚdus sp. nov. is the presence of 7 spines on the exopods of legs 1-4, because in other species of the genus the maximum number of spines on the exopod of any leg is 6, although several species bear an additional rudimentary seta on the exopod. The armature sequence on the endopods of legs 1-4 (8-8-7-7) is also an outstanding diagnostic feature shared only with SK bẚsetatus sp. nov. ( Table 3 View TABLE 3 ), which differs from S. frẚgẚdus sp. nov. in the presence of 2 setae on the lamellate exopod of leg 5. The fusion of the second endopodal segment and the terminal claw of the maxilliped of S. frẚgẚdus sp. nov. is an unusual feature within the genus, which is only known in S. ẚnflatus, as figured by Sars (1921) and S. fusiformis sp. nov.
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.