Metacrangon hikurangi, Komai & Ahyong, 2010
|
publication ID |
https://doi.org/ 10.1080/00222933.2010.520823 |
|
persistent identifier |
https://treatment.plazi.org/id/710787D3-6758-0F6C-5815-FC18FCD2BDB5 |
|
treatment provided by |
Felipe |
|
scientific name |
Metacrangon hikurangi |
| status |
sp. nov. |
Metacrangon hikurangi View in CoL sp. nov.
( Figures 4–6 View Figure 4 View Figure 5 View Figure 6 )
Material examined
Holotype. Hikurangi Margin , east coast of North Island, New Zealand, 40 ◦ 02.22– 02.14 ′ S, 177 ◦ 48.06–47.97 ′ E, 1171–1172 m, RV Sonne, SO 191-3 / 241, 7 March 2007, female (CL 10.6 mm), NIWA 31943 View Materials .
Description
Body ( Figures 4 View Figure 4 , 5A,D View Figure 5 ) moderately robust. Rostrum ( Figures 4 View Figure 4 , 5A,B View Figure 5 ) dorsoventrally flattened, narrowly subtriangular in dorsal view, directed forward, about 0.2 times as long as carapace; tip rounded in dorsal view; dorsal surface faintly concave in distal half, slightly carinate medially in posterior half; lateral margin nearly straight in lateral view, merging into orbital margin; midventral carina low, ventral margin nearly straight in lateral view. Carapace ( Figures 4 View Figure 4 , 5A View Figure 5 ) not widened posteriorly, distinctly
third maxilliped, ventral view (setae omitted); (C) left first pereopod, lateral view; (D) same, subchela, dorsal (extensor) view; (E) left second pereopod, lateral view; (F) right third pereopod, lateral view; (G) left fourth pereopod, lateral view; (H) same, dactylus, outer (flexor) view; (I) left fifth pereopod, lateral view; (J) endopod and appendix masculina of left second pleopod, mesial view; (K) posterolateral part of uropodal exopod, dorsal view (setae omitted). Scale bars: 1 mm for A, C–G, I; 0.5 mm for H, J, K.
longer than wide postorbitally; surface covered with very short setae; dorsal midline with two prominent, laterally compressed teeth; anterior tooth styliform, arising slightly posterior to rostral base, somewhat ascending (angle against horizontal plane of carapace about 50 ◦), overlapping rostrum, tip falling short of rostral tip; posterior (cardiac) tooth slightly smaller than anterior tooth, hooked, arising at 0.65 of CL; submedian tooth moderately large; hepatic tooth moderately large, followed by clearly delineated epibranchial ridge; antennal tooth moderately small, directed forward in both dorsal and lateral views, acuminate, slightly falling short of rostral tip; orbital cleft absent; anterolateral margin between antennal and branchiostegal teeth concave, with minute denticle inferior to base of antennal tooth; branchiostegal tooth strong, directed forward in dorsal view, slightly ascending in lateral view, reaching dorsodistal margin of antennal basicerite; pterygostomial tooth small ( Figure 5C View Figure 5 ), not visible in lateral view; postorbital carina clearly delimited, accompanied by suture; epibranchial carina distinct.
Abdomen ( Figures 4 View Figure 4 , 5D View Figure 5 ) weakly sculptured; anterior five somites each with broad, distinctly delimited mid-dorsal carina, mid-dorsal carina on anterior four somites not extending to posterodorsal margin; anterior end of mid-dorsal carina on second somite slightly projecting anteriorly. First pleuron with blunt tooth at posteroventral angle; second pleuron with obtuse tooth at middle of ventral margin; third pleuron without conspicuous tooth or projection on ventral margin; fourth pleuron with faintly concave ventral margin, posterolateral margin rounded. Fifth somite with posterodorsal margin slightly produced medially, posterolateral margin unarmed; pleuron shallowly concave on lateral surface. Sixth somite 1.6 times longer than wide submedian carinae distinct, slightly curving, not reaching posterodorsal margin; dorsolateral carina distinct; posterodorsal margin faintly bilobed; pleuron flared laterally, posteroventral tooth moderately strong; posterolateral process elongate, somewhat curved laterally, terminating in blunt tip. Telson ( Figure 5D View Figure 5 ) without dorsolateral spines; tip acute, with three pairs of plumose setae ( Figure 5E View Figure 5 ).
Thoracic sternum widened posteriorly; fifth sternite with thick median carina bearing small acute tooth directed ventrally; sixth to eighth sternites with thick median carina becoming lower posteriorly. Abdominal sternites bearing sharp tooth in first to third somites, blunt tubercle in fourth and fifth somites; sixth sternite shallowly depressed medially.
Eye ( Figure 5A,B View Figure 5 ) slightly longer than wide; cornea as wide as proximal part of eyestalk, darkly pigmented, corneal width about 0.13 of CL; eyestalk with papilla-like dorsal tubercle.
Antennular peduncle ( Figure 5A,B View Figure 5 ) slightly falling short of midlength of antennal scale. First segment with short, blunt distolateral process, distomesial margin unarmed; stylocerite directed forward, terminating in acute tooth, slightly overreaching tip of distolateral process of first segment, lateral margin slightly angular. Second segment distinctly widened distally, with short, blunt distolateral process.
lateral view; (E) same, chela, lateral view; (F) third pereopod, lateral view; (G) fourth pereopod, lateral view; (H) same, dactylus, flexor view; (I) fifth pereopod, lateral view; (J) same, dactylus, flexor view. Scale bars: 2 mm for A–D, F, G, I; 1 mm for E, H, J.
Third segment wider than long. Outer flagellum over-reaching distal margin of lamella of antennal scale by 0.4 length, consisting of 13 articles.
Antennal basicerite ( Figure 5A,B View Figure 5 ) stout, with sharply pointed dorsodistal lateral angle, ventrolateral tooth exceeding beyond dorsodistal lateral angle. Antennal scale 0.50 times as long as carapace and 2.7 times longer than wide; lateral margin slightly concave; distolateral tooth moderately wide, slightly over-reaching rounded distal margin of lamella.
Third maxilliped relatively slender, over-reaching antennal scale by half length of ultimate segment; ultimate segment ( Figure 6A View Figure 6 ) gradually tapering distally, about 7.3 times longer than wide; penultimate segment about 2.4 times longer than wide ( Figure 6A View Figure 6 ); antepenultimate segment with two minute spinules subdistally on ventral surface.
First pereopod ( Figure 6B,C View Figure 6 ) reaching distal margin of antennal scale; palm 3.4 times longer than wide, not widened proximally or distally, lateral and mesial margins nearly straight; thumb relatively slender; carpus with small ventrolateral tooth; merus with one small dorsodistal tooth, ventral margin sinuous, crested. Second pereopod ( Figure 6D View Figure 6 ) reaching nearly to midlength of antennal scale; dactylus about 0.4 times as long as palm ( Figure 6E View Figure 6 ); length ratio of chela to ischium 1: 1.9: 1.8: 1.3. Third pereopod ( Figure 6F View Figure 6 ) nearly reaching distal margin of antennal scale by tip of dactylus; length ratio of dactylus to ischium 1: 2.0: 3.1: 2.1: 2.3. Fourth pereopod ( Figure 6G View Figure 6 ) moderately stout, slightly over-reaching midlength of antennal scale by dactylus; dactylus ( Figure 6H View Figure 6 ) narrowly spatulate, about 0.7 times as long as propodus, margins naked; dactylus–propodus articulation about 45 ◦; propodus about 5.6 times longer than wide. Fifth pereopod ( Figure 6I View Figure 6 ) shorter than fourth pereopod, reaching base of branchiostegal tooth; dactylus ( Figure 6J View Figure 6 ) subspatulate, more slender than that of fourth pereopod, about 0.7 times as long as propodus; setation much less than in fourth pereopod.
Uropodal exopod ( Figure 5F,G View Figure 5 ) with subtruncate posterolateral tooth; no spinule mesial to posterolateral tooth ( Figure 5G View Figure 5 ).
Colouration in life
Not known.
Size
The only known specimen is a female of pre-spawning moult, CL 10.6 mm.
Distribution
Known only from east coast of North Island of New Zealand, at depths of 1171– 1172 m.
Etymology
Named for the type locality; used as a noun in apposition.
| RV |
Collection of Leptospira Strains |
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.