A new tanaidacean subfamily, Bathytanaidinae (Crustacea: Paratanaididae), from the Australian continental shelf and slope Author Larsen, Kim Author Heard, Richard W. text Zootaxa 2001 2001-12-20 19 1 22 journal article http://doi.org/10.5281/zenodo.4618295 52ae2ec9-fbda-4d82-bf74-ab4257c79648 1175­5326 4618295 B9B4322E-4550-46A7-A34B-3A8392156A7C Bathytanais fragilis n. sp. ( Figs. 5­7 ) Material examined: 1 non­ovigerous female holotype , bl. 3.75 mm , NMV­J37854 , Slope Sta. 21 , 36°57.40’S , 150°18.80’E . Depth 220 m . 1 non­ovigerous female paratype , NMV­J37855 , Sta. MSL­EG 70 , 37°53.39’S , 148°14.40’E . Depth 43 m . 2 non­ovigerous female paratypes , mouthparts and limbs dissected from, NMV­J28449 & J37875 , Slope sta. 40 , 38°17.70’S , 149°11.30’E . Depth 400m . Collected by Drs. Poore, Coleman and Lew Ton . Other material: 3 non­ovigerous females , Slope Sta. 21 , 36°57.40‘S , 150°18.80’E . Depth 220 m . 3 ovigerous females , 12 non­ovigerous females , 10 manca III. MSL©EG Sta. 70 , 37°53.39’S , 148°14.40’E . Depth 43 m . 14 non­ovigerous females , Grip Point survey CPBS Sta. 22N , 38°20.60’S , 145°13.46’E . Depth 13 m . Diagnosis: Antenna article 2 ventral extension thin and transparent. Antenna article 3 with anteriorly directed dorsal spiniform seta. Uropod endopod uniarticulated. Description (adult female). Body ( Fig. 5 A, B): Slender, subcylindrical, approximately 8 times as long as broad. Carapace ( Fig. 5 D): As long as pereonite 1 and 2 combined, width 0.75 times length, anterolateral corners curving anteriorly, consisting of 8 plates. Eye­lobes square and blunt. Pereonites : Smooth. Pereonite 1 wider than long. Pereonites 2­4 length subequal width. Pereonite 5 similar in length and width, shorter than anterior pereonites. Pereonite 6 length and width subequal, shorter than anterior pereonites, ventral surface with anterolateral punctuated lobe. Pleonites : 1­5 subequal, approximately 4.0 times wider than long. Pleotelson ( Fig. 5 C): Marginally exceeds length of last pleonite. Antennule ( Fig. 6 A): 1.2 times as long as cephalothorax. Article 1 longer than rest of antennule, 2 simple setae medially. Article 2 less than 0.3 times length of article 1 , distal margin with 1 long simple seta. Article 3 half as long as article 4 , with 1 long setulose seta. Article 4 as long as article 2 , with 1 simple short proximal seta, 1 distal simple seta and 3 distal setulose setae twice as long as antennule itself. Antenna ( Fig. 6 B): Only marginally longer than that of antennule article 1 . Article 1 smooth, wider than long. Article 2 with thin transparent ventral extension, 2 simple medial setae and 1 simple distal seta. Article 3 as long as article 4 , with dorsal spiniform seta. Article 4 as long as article 5 , with 1 long serrated distal seta on ventral margin, 3 short sensory setae and 1 simple distal seta. Article 5 twice as long as article 1 , with 4 long setulose distal setae longer than antenna as a whole. Article 6 minute without any visible features. Mouthparts: Labrum ( Fig. 6 C) smooth, with pointed apex. Left mandible ( Fig. 6 E) with strongly defined lacina mobilis with several denticulations, incisor unidentate. Right mandible ( Fig. 6 F) incisor bidentate. Maxillule ( Fig. 6 G) with 7 thick terminal setae and row of setae, palp not recovered. Maxilla ( Fig. 6 H) ovoid and smooth. Labium ( Fig. 6 D) with indent on anterolateral corners. Maxilliped ( Fig. 6 I) endites with 2 short flat setae; palp article 1 , square and smooth; article 2 , inner margin longer than outer, 3 setulated setae on inner distal margin; article 3 with 4 setulated setae; article 4 , oval, inner margin with 4 setulated distal setae and several fine setules, outer margin with 1 setulated seta. Epignath not recovered. FIGURE 5. Bathytanais fragilis , holotype, female scale bar 2.5 mm. A) Dorsal view. B) Lateral view. C) Pleotelson. D) Cephalothorax. Cheliped ( Fig. 6 J): Basis with depression midlength, smooth, twice as long as wide. Merus ovoid, 1 simple medial seta on ventral margin. Carpus oval, longer than basis, 2 simple setae on ventral margin and 1 seta on dorsal margin. Propodus ( Fig. 6 K) expanded distally beyond attachment of dactylus, row of serrated setae flanking dactylus insertion. Fixed finger with strong apex, 2 simple setae on ventral margin and 3 setae on cutting edge. Dactylus narrow. Oostegites : originating from pereonites 1­4 . FIGURE 6. Bathytanais fragilis , female paratype scale bars A­B 1 mm, E­I 0.02 mm, J 0.5 mm. A) Antennule. B) Antenna. C) Labrum. D, Labium. E) Left mandible. F) Right mandible. G) Maxillule. H) Maxilla. I) Maxilliped. J) Cheliped. K) Cheliped propodus. Pereopod 1 ( Fig. 7 A): Coxa but distinct. Basis width increasing distally, with 3 simple dorsal setae. Ischium with 1 simple seta. Merus with 2 simple ventral distal setae and 1 simple dorsal seta. Carpus half as long as merus, with 1 short simple ventral seta and 1 longer dorsal seta. Propodus as long as merus, tapering distally, with 1 short simple ventral distal seta and 2 long dorsal setae. Dactylus and terminal seta not fused, combined longer than propodus. Terminal seta 2.0 times longer than dactylus. Pereopod 2 ( Fig. 7 B): Similar to pereopod 1 except: Ischium, and carpus smooth. Merus about 0.3 times length of that of pereopod 1 . Propodus less elongated, with 1 simple seta on each margin. Pereopod 3 ( Fig. 7 C): Similar to pereopod 2 except: Basis with 2 setae. Ischium and merus each with 1 seta. Propodus with 2 short and 3 long simple distal setae. FIGURE 7. Bathytanais fragilis , female paratype, scale bar A­F 0.25 mm, G­H 0.1 mm. A) Pereopod 1. B) Pereopod 2. C) Pereopod 3. D) Pereopod 4. E) Pereopod 5. F) Pereopod 6. G) Pleopod. H) Uropod. Pereopod 4 ( Fig. 7 D): Lateral coxa absent, but a ventral plate is interpreted as coxa. Basis stout, length approximately 1.5 times width, with 1 simple dorsal seta and 2 sensory ventral setae. Ischium width 3.0 times length, with 2 simple ventral setae. Merus ovoid, shorter than carpus, with 2 short stout denticulated ventral setae. Carpus as long as ischium and merus together, with denticulate cuticular scales and 2 short stout denticulated distal setae. Propodus as long as carpus, with 1 short thick dorsal distal seta, 1 sensory and 1 flat serrated dorsal setae, Dactylus and terminal seta fused into a claw with denticles. Pereopod 5 ( Fig. 7 E): Similar to pereopod 4 except: Basis longer and with several simple setae and only 1 sensory seta. Merus quadrate and with denticulated scales. Propodus without sensory seta. Pereopod 6 ( Fig. 7 F): Similar to pereopod 4 except: Basis longer and smooth. Merus with denticulated scale and 1 short stout seta. Carpus with 1 short stout denticulated seta and scales as well as paired short thick bifurcate distal setae. Propodus with 1 short stout denticulated seta and 3 thick hook­shaped distal setae. Pleopods ( Fig. 7 G): All 5 pairs similar. Protopod trapezoidal. Exopod armed with 13 plumose setae, 2 distal setae shorter and stouter than rest. Endopod with 12 plumose setae. Uropods ( Fig. 7 H): Protopod smooth, quadrate. Endopod with 1 article, width decreasing 30 % midlength, with 1 simple seta and 2 sensory setae midlength and 5 long simple distal setae. Exopod with 1 article, with 1 simple seta at midlength and 2 long simple distal setae. Etymology: Named after the fragile, ventral extension on antenna article 2 , which is transparent and much less rigid as compared to other species in the genus (Latin: fragilis = fragile). Remarks : Bathytanais fragilis is easily separated from other species of Bathytanais by the thin, transparent ventral extension of antenna article 2 . The weakness of this process indicate that this species is the link between Bathytanais and Pseudobathytanais .