Bathytanais arenamans, Larsen & Heard, 2001

Larsen, Kim & Heard, Richard W., 2001, A new tanaidacean subfamily, Bathytanaidinae (Crustacea: Paratanaididae), from the Australian continental shelf and slope, Zootaxa 19, pp. 1-22 : 8-11

Bathytanais arenamans n. sp. ( Figs. 3 & 4 )

Material examined: Holotype: Non­ovigerous female, P61357, body length 3.1 mm, Sta. SO 5­83­B2, 19º56,7’S. 117º53,6’E. Depth 41 m. Paratypes: 2 Non­ovigerous females, P61358, same locality. Collected by staff on board RV “Soela” CSIRO 1983 .

Other material: 24 Non­ovigerous female, P52206, same locality . 2 females, P52191, Sta. No. SO2­83­B12 , Lat. 19º56.9'S, Long. 117º53.7' E. Depth 43 m . 9 females, P52349, Sta. No. SO4­83­B1 , Lat. 19º58.9'S, Long. 117º51.7'E. Depth 42 m . 1 female, P52351, Sta. No. SO4­83­B7 , Lat. 19º30.8'S, Long. 118º49.4' E. Depth 38 m . 3 females, P52195, Sta. No. SO3­83­B2 , Lat. 19º56.4'S, Long. 117º53.9' E. Depth 44 m . 1 female, P52204, Sta. No. SO4­83­B17 , Lat. 20º00.2'S, Long. 117º00.5'E. Depth 52 m . 1 female, P52199, Sta. No. SO4­83­B2 , Lat. 19º56.7'S, Long. 117º53.8' E. Depth 42 m . 1 female, P52200, Sta. No. SO4­83­B10 , Lat. 19º05.0'S, Long. 118º57.9'E. Depth 86 m . 1 female, P04971, Sta. No. SO2­83­B3 , Lat. 19º55.9'S, Long. 117º56.8'E. Depth 42 m . 4 females, P52191, SO2­ 83­B12 , Lat. 19º56.9', Long. 117º53.7'E. Depth 43m. 1 juvenile, P52208, Sta. No. SO5­ 83­B5 , Lat. 19º04.8'S, Long. 118º50.7'E. Depth 81 m .

Diagnosis: Antennal 2 article 2 as deep as long, with disto­ventral quadrate process extending just past articulation of article 3 and 4; article 3 inserted dorsally into article 2, rounded disto­dorsally and armed with blunt, subapical tooth. Labium without antero­lateral projections. Uropod exopod about half as long as endopod.

Description (adult female).

Body ( Fig. 3 A): Slender, sub­cylindrical, approximately 8 times longer than broad.

Cephalothorax ( Fig. 3 B): Shorter than length of pereonites 1 and 2 together, width 0.75 length, antero­lateral corners curving anteriorly. Eye lobes smoothly curved.

Pereonites: Pereonite 1 wider than long, extending over cephalothorax at pereopod attachment. Pereonites 2, 3 and 5, longer than wide. Pereonites 4 and 6 length subequal width.

Pleon: Pleonites 1­5 subequal, width approximately 4.0 length. Pleotelson as long as 2 last pleonites together.

Antennule ( Fig. 3 C): Shorter than cephalothorax. Article 1 greatly swollen, only marginally longer than wide, longer than combined length of rest of antennule (excluding setae), with several sensory setae on inner margin and 2 short simple distal setae. Article 2 more than half as long as article 1, distal margin with 2 long simple setae and 2 short sensory setae. Article 3 one quarter as long as article 2, with 1 long setulated and 1 simple distal setae. Article 4 half as long as article 2, with 5 distal serrated setae twice as long as antennule.

Antenna ( Fig. 3 D): as long as combined length of 3 first articles of antennule. Article 1 smooth, as long as article 3. Article 2 with 1 distal dorsal simple seta, ventral process extending beyond article 3 with on distal simple ventral seta. Article 3 quadrate with short dorsal spiniform seta. Article 4 longer than article 5, armed distally with 1 long serrate seta, 1 short simple seta and 3 sensory setae. Article 5 half as long as article 4, with 2 long setulated distal setae. Article 6 minute, with 2 setulose setae longer than antenna itself, 2 long­ and 1 short simple setae.

Mouthparts: Labrum ( Fig. 3 E) setose, with rounded apex. Mandibles ( Figs. 3 F & G) molar longer than incisor, left mandible with strongly defined lacina mobilis with several denticulations, incisor unidentate, right mandible with broad and bidentate incisor. Maxillule ( Fig. 3 H) with 7 thick terminal setae and row of setae, palp not recovered. Maxilla ( Fig. 3 I) triangular. Labium ( Fig. 3 J) tapering distal and with numerous distal setulated scales. Maxilliped ( Fig. 3 K) endites with 1 simple seta on inner corner and 2 flat distal setae; palp article 1, outer margin longer than inner, smooth; article 2, inner margin longer than outer, with 3 setulated setae on inner margin; article 3, with 4 setulated setae on inner margin; article 4, rectangular, inner margin with 4 setulated distal setae, outer margin with 1 setulated seta. Epignath not recovered.

Cheliped ( Fig. 3 L): Basis twice as long as wide with 1 minute simple distal seta,. Merus ovoid, with 1 simple seta medially on ventral margin. Carpus oval, marginally longer than basis, with 2 simple setae on ventral margin, 2 setae on dorsal margin. Propodus slender, with 2 distal dorsal setae at dactylus insertion and 1 simple seta medially at dactylus insertion. Fixed finger with strong bifurcated apex, 2 simple setae on ventral margin, 3 on cutting edge. Dactylus narrow, with 1 seta on its dorsal surface.

Oostegites: originating from pereonites 1­4.

Pereopod 1 ( Fig. 4 A): Longer than other pereopods. Coxa with 1 simple seta. Basis as long as 3 succeeding articles combined, with 1 proximal simple setae on ventral margin. Ischium with 2 simple setae on dorsal margin. Merus longer than carpus, with 1 simple distal seta on dorsal margin. Carpus two thirds as long as propodus, with 2 short simple distal setae. Propodus as long as merus, tapering distally, with 2 short and 1 long simple distal setae. Dactyl and terminal seta together longer than propodus.

Pereopod 2 ( Fig. 4 B): Similar to pereopod 1, except: Merus smooth and as long as carpus. and propodus as long as dactylus and terminal setae combined.

Pereopod 3 ( Fig. 4 C): Similar to pereopod 2, except: Ischium smooth, merus with 1 simple seta, carpus smooth, dactyl and terminal seta together longer than propodus.

Pereopod 4 ( Fig. 4 D): Basis stout with 1 simple and 1 sensory distal setae. Ischium with 2 simple ventral setae. Merus ovoid, longer than carpus, with 1simple, 1 short stout denticulated seta, and denticulated scales. Carpus shorter than propodus, with denticulated scales, 1 simple setae and 4 short stout denticulated distal setae. Propodus with 1 dorsal sensory, 1 long serrated, 1 spiniform, and 1 spiniform setulose distal setae. Dactyl and terminal spine fused into claw with setules.

Pereopod 5 ( Fig. 4 E): As pereopod 4, except: Basis with 1 simple dorsal seta. Carpus with 3 spiniform denticulated distal setae.

Pereopod 6 ( Fig. 4 F): As pereopod 4 except: Basis smooth, ischium with 1 simple seta, merus with denticulated scales and 1 short denticulated setae, carpus with 4 short denticulated distal setae, propodus without sensory seta but with 2 spiniform subdistal and 3 stout setulated distal setae as long as dactylus.

Pleopods ( Fig. 4 G): All 5 pairs similar. Protopod trapezoidal. Exopod armed with 19 plumose setae. Endopod, inner margin finely setose, with 14 plumose setae, 2 distal setae shorter and stouter than rest.

Uropods ( Fig. 4 H): Protopod elongated, smooth. Endopod articulation weak, with 1 simple and 2 sensory setae at midlength on second article element and 4 long­ 1 short simple­ and 1 sensory distal setae. Exopod with 3 short­ and 1 long simple setae.

Male: unknown

Etymology: Named after the preferred habitat of most Bathytanais species (Latin: arena­mans = sand­lover).

Habitat: Specimens living in sandy bottom at 41 m depth on the Northwest Australian shelf off Western Australia. Specimens were found in tubes consisting of sand grains and mucus.

Remarks: Bathytanais arenamans is distinguished from the other known members of the genus by the shape of antennal article 1 with is swollen and only marginally longer than wide. B. arenamans superficially resembles B. juergeni . Article 3 of antenna 2 in B. arenamans , however, has a subapical blunt, tooth­like seta instead of the acute disto­dorsal process that characterizes B. juergeni . Also ventral process of antenna article 2 does not extend beyond article 3 in B. juergeni .

Figures

FIGURE 3. Bathytanais. arenamans, female A holotype, B­L dissected paratype. A) Dorsal view. B) Cephalothorax. C) Antennule. D) Antenna. E) Labrum. F) Left mandible. G) Right mandible. H) Maxillule. I) Maxilla. J) Labium K) Maxilliped. L) Cheliped.

FIGURE 4. Bathytanais arenamans, female paratype. A) Pereopod 1. B) Pereopod 2. C) Pereopod 3. D) Pereopod 4. E) Pereopod 5. F) Pereopod 6. G) Pleopod. H) Uropod.