Obesutanais sigridae, Larsen & Błażewicz-Paszkowycz & Cunha, 2006

Larsen, Kim, Błażewicz-Paszkowycz, Magdalena & Cunha, Marina R., 2006, Tanaidacean (Crustacea: Peracarida) fauna from chemically reduced habitats-the lucky strike hydrothermal vent system, mid-atlantic ridge, Zootaxa 1187, pp. 1-36 : 16-18

publication ID	https://doi.org/ 10.5281/zenodo.2646092
publication LSID	lsid:zoobank.org:pub:C020B152-CDE8-47BF-B2B4-7C53AC238875
persistent identifier	https://treatment.plazi.org/id/038887F2-684D-8272-5515-7850C4E8F8D1
treatment provided by	Plazi
scientific name	Obesutanais sigridae
status	sp. nov.

Treatment

Obesutanais sigridae View in CoL n. sp. ( Figs. 5 View FIGURE 5 , 6 View FIGURE 6 )

Material examined

Holotype: ovigerous female ( ZMUC CRU4904 ), inside the vent field, 37°17.438’ N, 32º16.599’W, 1685 m, RV Prof. Logachev, TVassisted grab, TTR10, station AT265GR, August 2000 GoogleMaps . Paratypes: 1 ovigerous female, 1 nonovigerous female, 1 manca ( ZMUC CRU4905 ), same data. 1 nonovigerous female (dissected), same data. Other material: 1 female, 37º17.332’ N, 32º16.551’ W, 1710 m, RV Prof. Logachev, TVassisted grab, TTR 10, station AT267GR, August 2000 GoogleMaps . 1 female, 37º17.446’ N, 32º16.611’ W, 1675 m, RV Prof. Logachev, TVassisted grab, TTR10, station AT273GR, August 2000 GoogleMaps .

Diagnosis

Female. Pereonite 6 threequarters length of pereonite 5. Pereopods long (longer than pleon). Antennule article 3 without spiniform setae. Pereopods 4–6 dactylus and unguis partly fused but not into a claw. Uropods longer than pleotelson.

Etymology Named in honour of our close friend, Mrs. Sigrid Dawn Hart, editor of Gulf and Caribbean Research.

Description

Female. Body length 1.2 mm.

Body ( Fig. 5A, B View FIGURE 5 ). Very stout, only about 3 times as long as broad, tapering in distal direction.

Cephalothorax. As long as combined length of pereonites 13. Eyelobes absent.

Pereonites. All wider than long and progressively narrower posteriorly towards the pleotelson. Pereonite 1 shortest, pereonite 4 longest.

Pleon. 0.25 times as long as total body length. All pleonites subequal in length but tapering in width posteriorly. Pleotelson longer than combined length of two pleonites.

Antennule ( Fig. 5C View FIGURE 5 ). Marginally shorter than cephalothorax. Article 1 longer than rest of antennule, with six relatively long simple setae and three groups of pinnate distal setae. Article 2 only 0.2 times as long as article 1, with two simple distal setae. Article 3 twice as long as article 2, with one pinnate and seven simple distal setae.

Antenna ( Fig. 5D View FIGURE 5 ). Almost as long as antennule but only onethird as wide. Article 1 not broader than following articles, naked. Article 2 longer than article 3, with one dorsodistal seta. Article 3 shorter than article 2, with one dorsodistal seta. Article 4 longer than other articles, with four dorsodistal setae and proximal setules. Article 5 as long as article 2 with one simple distal seta. Article 6 minute, with five setae.

Mouthparts. Labrum ( Fig. 5E View FIGURE 5 ) flat and with several setules. Mandibular molar broad and longer than incisor, with terminal ring of blunt denticles interrupted by small group of proximal spines. Left mandible ( Fig. 5 View FIGURE 5 F–G) lacinia mobilis longer than incisor, with multiple denticles; incisor broad, with two denticles. Right mandible ( Fig. 5H & I View FIGURE 5 ) incisor with three denticles. Labium not recovered. Maxillule ( Fig. 5J View FIGURE 5 ) endite with eight distal spiniform setae; palp not recovered. Maxilla not recovered. Maxilliped ( Fig. 5K View FIGURE 5 ) basis apparently without setae at palp insertion. Endites almost as wide as basis, with two setae and one inner distal process. Palp article 1 naked; article 2 with three finely serrated inner setae and one simple outer seta; article 3 with two finely serrated and two simple inner setae; article 4 with five finely serrated inner setae and one simple outer seta. Epignath not recovered.

Cheliped ( Fig. 6A View FIGURE 6 ). Basis divided unequally by small sclerite attached proximally, shorter than carpus, with one seta near sclerite insertion. Merus with one ventral seta. Carpus longer and wider than propodus including the fixed finger, with three ventral setae, two small dorsal setae and setules along the entire dorsal margin. Propodus with one seta by dactylus insertion. Fixed finger with two ventral setae and three on inner margin, and several prominent denticles on inner margin. Dactylus as long as fixed finger.

Pereopod 1 ( Fig. 6B View FIGURE 6 ). Longer than other pereopods. Coxa with one simple seta. Basis longer than three succeeding articles combined, with two dorsal setae and multiple dorsal setules. Ischium with one ventral seta. Merus as long as carpus, widening distally, with one tiny ventrodistal seta and setules and cuticular scales. Carpus 0.8 times as long as propodus, with four simple distal setae and scattered setules and cuticular scales. Propodus half as long as basis, with three dorsal and one ventral subdistal setae. Dactylus and unguis shorter than propodus and not fused to a claw, of subequal length.

Pereopod 2 ( Fig. 6C View FIGURE 6 ). As pereopod 1 except: ischium naked. Merus with two simple distal setae, one of which is longer than carpus. Carpus with two long (almost as long as propodus), two small, and one spiniform distal setae. All articles except propodus, with multiple setules and cuticular scales.

Pereopod 3 ( Fig. 6D View FIGURE 6 ). As pereopod 1 except: basis with only one dorsal seta. Carpus with two short, one long, and one short spiniform setae. Propodus with small ventrodistal spiniform seta, two simple dorsodistal setae and dorsal spine, with setules only on proximal part. Dactylus with one simple distal seta.

Pereopod 4 ( Fig. 6E View FIGURE 6 ). Basis 3 times as wide as in pereopods 1–3, longer than three succeeding articles combined, with several scattered setules. Ischium with two ventral setae. Merus longer than carpus, widening distally, and with one spiniform distal seta and scattered setules and cuticular scales. Carpus twothirds as long as propodus, with one spiniform seta and cuticular scales. Propodus with serrated dorsal margin, with one dorsodistal seta, dorsal spine, and two spiniform ventral setae. Dactylus and unguis incompletely fused to a claw and combined shorter than propodus. Dactylus with ventral serration longer than ungius. Unguis with bifurcate tip (not visible on illustration due to appendage orientation).

Pereopod 5 ( Fig. 6F View FIGURE 6 ). As pereopod 4 except: basis with one setulose dorsal seta and scattered setules. Carpus with two multifurcate spiniform setae and cuticular scales. Propodus with dorsomedial setulose seta.

Pereopod 6 ( Fig. 6G View FIGURE 6 ). As pereopod 4 except: carpus twothirds as long as propodus, with one simple seta, three spiniform setae and cuticular scales. Propodus half as long as length of basis, with three dorsodistal setae, dorsal spine, and two spiniform ventral setae.

Pleopod ( Fig. 6H View FIGURE 6 ). Basal article naked. Exopod with one outer and seven inner plumose setae, no gap between proximal seta and others. Endopod with 11 simple inner setae, large gap between proximal seta and others.

Uropods ( Fig. 5L View FIGURE 5 ). Basal article shorter than first endopod pseudoarticle, naked. Endopod with two partly fused articles, shorter than pleotelson; article 1 with two pinnate distal setae; article 2 with four distal simple setae and one thick specialized seta. Exopod uniarticulated, threequarters as long as endopod, with one medial seta and one simple and one thick specialized distal seta.

Remark Specimens were found in very heavy tubes consisting of densely packed mud particles. This species is quite common and abundant in other Lucky StrikeMAR samples.