Metagathotanais Bird & Holdich
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publication ID |
https://doi.org/ 10.11646/zootaxa.3630.3.2 |
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publication LSID |
lsid:zoobank.org:pub:41BD1952-5232-4332-B722-DE99777DD6B4 |
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DOI |
https://doi.org/10.5281/zenodo.6155881 |
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persistent identifier |
https://treatment.plazi.org/id/CB208719-9806-D678-2E96-199FFE07FB1E |
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treatment provided by |
Plazi |
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scientific name |
Metagathotanais Bird & Holdich |
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Genus Metagathotanais Bird & Holdich View in CoL
Type species: Metagathotanais insulcatus Bird & Holdich
Diagnosis, female: (modified after Bird & Holdich 1988) cephalothorax shorter than pereonites 1 and 2 together. Pereonite-6, pleonites and pleotelson fused or partly fused. Antennule four-articled, with or without minute terminal cap-like article. Antenna six-articled, article-2 with dorsal seta. Mandible molar reduced, lacinia mobilis of left mandible small and spiniform or reduced. Maxillule endite with eight to ten terminal spiniform setae. Maxilliped bases and endites together oval or heart-shaped. Epignath without terminal spiniform seta. Cheliped sclerites (‘pseudocoxa’) fused ventromedially, not protruding below ventrum of cephalothorax. Uropod basis and endopod fused and without exopod.
Male. Generally as the female but the pleon fusion is either be incomplete or absent. Mouthparts functional. Reduced pleopods present,
Metagathotanais furcilla n. sp. Larsen & Bird Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3
Material examined. Holotype: non-ovigerous female (Reg. # ZMH K-43312)), ANDEEP II, sample # DZMB-HH 10445, station 137, 63°44.98’S, 47°75’W, 4976 m, 14 March 2002, EBS-supra. Paratypes (Reg. # ZMH K-43313): one fragmented non-ovigerous female, one preparatory male (dissected), and one non-ovigerous female (dried out), ANDEEP II, sample # DZMB-HH 10444, same locality and date as holotype, EBS-epi.
Diagnosis. Pereonite-6, pleonites and pleotelson incompletely fused in both genders. Antennule with minute terminal cap-like article. Antenna article-2 with one short dorsomedial and one longer dorsodistal setae; article-3 naked. Lacinia mobilis of left mandible reduced. Maxillule endite with ten terminal spiniform setae. Maxilliped basis with one outer seta; endites naked. Pereopods 1–3 merus and carpus with short spiniform setae. Pereopods 1–6 propodus with two to four dorsodistal spines. Uropod long (marginally shorter than pleotelson)
Etymology. Name derived from the Latin for ‘fork’, (in diminutive) as a noun, alluding to the diagnostic dorsodistal spines on the propodus of the pereopods.
Description. Non-ovigerous female (holotype, not dissected).
Body ( Fig. 1 View FIGURE 1 A). Heavily calcified, 8.5 times as long as wide. Cephalothorax with clear lateral shield, naked; lateral margins almost straight in dorsal view; longer than wide, shorter than pereonites 1 and 2 combined. Pereonites with weak lateral shoulders; pereonite 1 wider than long; pereonites 2–5 longer than wide, subequal; pereonite 6 square or marginally longer than wide. Pleon short (including pleotelson 0.15 times as long as total body length); all pleonites subequal and incompletely fused with pereonite-6, with each others and with pleotelson. Pleotelson longer than three last pleonites combined, acorn-shaped, apex rounded, with paired setae, and covered by dorsal plate.
Description. Preparatory male (paratype).
Body ( Fig. 3 View FIGURE 3 A, B). As non-ovigerous female except: Pleon short (including pleotelson 0.17 times as long as total body length).
Antennule ( Fig. 1 View FIGURE 1 B). Shorter than cephalothorax. Article-1 1.7 times as long as rest of antennule combined, with two simple and three setulose subdistal setae. Article-2 less than one-third as long as article-1, with one long simple and one setulated subdistal setae. Article-3 less than half as long as article-2, with dorsodistal process giving rise to two simple setae, one simple distal seta on ventral margin. Article-4 with one simple distal seta. Terminal cap-like article minute and partly fused to article-4, with at least two (broken) setae.
Antenna ( Fig. 1 View FIGURE 1 C). Shorter than antennule article-1. Article-1 naked. Article-2 with one subdistal seta and several setules. Article-3 longer than article-2, apparently naked but with dorsodistal process. Article-4 longer than combined length of other antenna articles, with one setulated distal seta. Article-5 as long as article-3, tapering and apparently naked. Article-6 minute, with one subdistal and three long simple distal setae.
Mouthparts. Labrum ( Fig. 1 View FIGURE 1 D) narrower than clypeus, distal edge setulose. Mandibles ( Fig. 1 View FIGURE 1 E, F) with no trace of functional molars although a non-chitinised process is present on right mandible. Right mandible ( Fig. 1 View FIGURE 1 E) incisor without denticles. Left mandible ( Fig. 1 View FIGURE 1 F) lacinia mobilis reduced to inner denticle completely fused with incisor, incisor blunt. Labium ( Fig. 1 View FIGURE 1 G) with small setulose outer process. Maxillule ( Fig. 1 View FIGURE 1 H) endite with ten spiniform distal setae and subdistal setules. Palp with two relatively short terminal setae. Maxilla ( Fig. 1 View FIGURE 1 I) ovoid, featureless. Maxilliped ( Fig. 1 View FIGURE 1 J) basis with one short seta on outer medial margin near palp insertion. Endites without setae but with blunt denticle. Palp article-1 naked, articles 2 and 3 with three pinnate setae on inner margin, article-4 only half as wide and long as article-3, with one simple outer and four pinnate inner setae. Epignath ( Fig. 1 View FIGURE 1 K) as long as maxillule palp, featureless.
Cheliped ( Fig. 1 View FIGURE 1 L). Basis naked, incompletely fused to sclerite, less than twice as long as merus. Merus with one medial seta. Carpus marginally longer than propodus including fixed finger, with one medioventral seta and one dorsodistal and one dorsomedial small setae. Propodus with one long rigid inner seta behind dactylus insertion. Fixed finger with one ventral seta and three setae on inner margin, inner margin with prominent distal carina. Dactylus as long as fixed finger, naked.
Pereopod-1 ( Fig. 2 View FIGURE 2 A). Coxa rounded, naked. Basis as long as combined length of carpus and propodus, naked. Ischium with one simple seta. Merus 0.7 times as long as carpus, widening distally, with one small spiniform ventrodistal seta. Carpus less than half as long as basis, with one dorsodistal and two ventrodistal small spiniform setae. Propodus longer than carpus, with one ventrodistal simple and one spiniform setae and two dorsodistal spines and scales. Dactylus and unguis combined shorter than propodus. Unguis longer than dactylus, with dorsodistal acute process.
Pereopods 2–3 ( Fig. 2 View FIGURE 2 B,C). As pereopod-1 except propodus with one spiniform seta only.
Pereopods 4–5 ( Fig. 2 View FIGURE 2 D,E). Coxa naked, partly fused to body. Basis longer than combined length of carpus and propodus, with one setulated ventromedial seta. Ischium with one seta. Merus shorter than carpus, widening distally, with two ventrodistal bayonet setae. Carpus less than half as long as basis, with one bone-shaped and three distal bayonet setae. Propodus marginally longer than carpus, with three bayonet setae and three dorsodistal spines. Dactylus and unguis subequal, together longer than propodus, not fused.
Pereopod-6 ( Fig. 2 View FIGURE 2 F). As pereopod-4 except: propodus with four bayonet setae and four dorsodistal spines. Pleopods ( Fig. 3 View FIGURE 3 C). All pairs similar, heavily calcified and immobile but not fused, without setae.
Uropod ( Fig. 1 View FIGURE 1 M). Marginally shorter than pleotelson. Basal article fused to uniarticulate endopod, with one medial and two distal setae.
Remarks. Metagathotanais furcilla n. sp. can be separated from the other two known species, M. insulcatus and M. loerzae Guerrero-Kommritz by the incomplete fusion of the pleonites and the dorsodistal spines of the propodi of pereopods 4–6; additionally, the short spiniform setae on the merus and carpus of pereopods 1–3 appear to be unique in this species.
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.
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