Bathytanais fragilis Larsen &amp; Heard 2001, n. sp.
Creators: name: Larsen, Kim
name: Heard, Richard W.
Publisher: name: Zenodo
Year: 2001
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Tanaidacea
Paratanaidae
Bathytanais
Bathytanais fragilis

description: <i>Bathytanais fragilis</i> n. sp. (Figs. 5­7) <i>Material examined:</i> 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 &amp; J37875, Slope sta. 40, 38°17.70’S, 149°11.30’E. Depth 400m. Collected by Drs. Poore, Coleman and Lew Ton. <i>Other material:</i> 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. <i>Diagnosis:</i> Antenna article 2 ventral extension thin and transparent. Antenna article 3 with anteriorly directed dorsal spiniform seta. Uropod endopod uniarticulated. <i>Description</i> (adult female). <i>Body</i> (Fig. 5 A, B): Slender, subcylindrical, approximately 8 times as long as broad. <i>Carapace</i> (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. <i>Pereonites</i>: 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. <i>Pleonites</i>: 1­5 subequal, approximately 4.0 times wider than long. <i>Pleotelson</i> (Fig. 5 C): Marginally exceeds length of last pleonite. <i>Antennule</i> (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. <i>Antenna</i> (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. <i>Mouthparts:</i> 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. <i>Cheliped</i> (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. <i>Oostegites</i>: originating from pereonites 1­4. <i>Pereopod 1</i> (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. <i>Pereopod 2</i> (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. <i>Pereopod 3</i> (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. <i>Pereopod 4</i> (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. <i>Pereopod 5</i> (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. <i>Pereopod 6</i> (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. <i>Pleopods</i> (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. <i>Uropods</i> (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. <i>Etymology:</i> 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: <i>fragilis</i> = fragile). <i>Remarks</i>: <i>Bathytanais fragilis</i> is easily separated from other species of <i>Bathytanais</i> by the thin, transparent ventral extension of antenna article 2. The weakness of this process indicate that this species is the link between <i>Bathytanais</i> and <i>Pseudobathytanais.</i>
description: Published as part of <i>Larsen, Kim &amp; Heard, Richard W., 2001, A new tanaidacean subfamily, Bathytanaidinae (Crustacea: Paratanaididae), from the Australian continental shelf and slope, pp. 1-22 in Zootaxa 19</i> on pages 12-16, DOI: 10.5281/zenodo.4618295