Bathytanais culterformis, 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 : 3-7

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Bathytanais culterformis

n. sp.

Bathytanais culterformis n. sp. ( Figs. 1 View FIGURE 1 & 2 View FIGURE 2 )

Material examined. – Holotype: Non­ovigerous female, P 61355 View Materials , body length 3.2 mm, Sta. SO 5­83 ­B2 , 19º56,7’S. 117 º53,6’E. Depth 41 m GoogleMaps . Paratypes: 2 non­ovigerous females, P 61356 View Materials , same locality. Collected by staff on board RV “Soela” CSIRO 1983 GoogleMaps .

Other material: 12 Non­ovigerous female, P 54288 View Materials , same locality GoogleMaps . 5 females, P 52195 View Materials , Sta. No. SO 3­83 ­B 2 , Lat. 19 º 56.4 'S, Long. 117 º 53.9 'E. Depth 44 m GoogleMaps . 1 female, P 52213 View Materials , Sta. No. SO 6­82 ­B 4 , Lat. 18 º 56.6 'S, Long. 118 º 44.9 'E. Depth 88 m GoogleMaps . 2 females, 1 manca, P 52211 View Materials , Sta. No. SO 6­83 ­B 1, Lat. 19 º03.0'S, Long . 119 º02.4'E. Depth 80 m GoogleMaps . 1 female, P 52198 View Materials Sta. No. SO 3­83 ­D 9, Lat. 19 º58.0'S, Long . 117 º 49.7 'E. Depth 43 m GoogleMaps . 7 females, P 52199 View Materials , Sta. No. SO 4­83 ­B 2, Lat. 19 º 56.7 'S, Long . 117 º 53.8 'E. Depth 42 m GoogleMaps . 1 female, P04972 View Materials . Sta. No. SO 3­83 ­B 7 , Lat. 19 º 30.8 'S, Long. 118 º 49.1 'E. Depth 38 m GoogleMaps . 1 female, P 52191 View Materials , SO 2­83 ­B 12, Lat. 19 º 56.9 ', Long . 117 º 53.7 'E. Depth 43m GoogleMaps . 1 female, P 52378 View Materials , Sta. No. SO 3­83 ­B 8 , Lat. 19 º 29.2 'S, Long. 118 º 52.5 'E. Depth 41 m. GoogleMaps

Diagnosis: Antenna with article 2 subquadrate, ventral margin blade­like, not serrated, slightly concave; disto­ventral margin subacute, with several setae. Article 3 of antenna not deeply recessed into article 2, with disto­dorsal and disto­ventral margins each produced into acute process. Labium with distal denticulated scales. Uropodal exopod almost as long as endopod.

Description (adult female)

Body ( Fig. 1 View FIGURE 1 A): Slender, sub­cylindrical, approximately 9 times longer than broad.

Cephalothorax ( Fig. 1 View FIGURE 1 B): Length near length of pereonite 1 and 2 together, width 0.75 length. Eye lobes acute.

Pereonites: Pereonite 1 wider than long. Pereonites 2­4 and 6, length subequal to width. Pereonite 5 longer than wide.

Pleon: Pleonites 1­5 similar in length and width, width approximately 4.0 length, all with 1 heavy articulated circumplumose seta. Pleotelson twice as long as last pleonite.

Antennule ( Fig. 1 View FIGURE 1 C): Longer than cephalothorax. Article 1 longer than rest of antennule, with several setules on outer margin. Article 2 longer than article 3, distal margin with 2 long simple setae and several setules. Article 3 length one quarter of article 4, with 1 simple and long setulated seta. Article 4 longer than article 2, with 1 simple and 5 distal setulated setae twice as long as antennule.

Antenna ( Fig. 1 View FIGURE 1 D): Length three quarters that of antennule. Article 1 lost. Article 2 with smooth ventral margin of the ventral expansion, distal ventral row of simple setae, 1 simple distal dorsal seta. Article 3 less than half as long as article 2, with dorsal spiniform seta and distal anteriorly directed ventral projection. Article 4 longer than article 3, with 1 long serrated distal seta on ventral margin and 3 short sensory setae. Article 5 as long as article 4, with 1 setulated distal seta of more than twice the length of the antennae. Article 6 minute with 3 setulose setae longer than antenna, 2 long and 1 short simple setae.

Mouthparts: Labrum ( Fig. 1 View FIGURE 1 E) flat, setose apex. Mandibles ( Figs. 1 View FIGURE 1 G & F) 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. 1 View FIGURE 1 I) with 7 thick terminal setae and dorsal row of setae, palp shorter than endite. Maxilla ( Fig. 1 View FIGURE 1 I) ovoid. Labium ( Fig. 1 View FIGURE 1 H) with setules on anterolateral corners and distal denticulated scales. Maxilliped ( Fig. 1 View FIGURE 1 J) endites with 1 seta on inner corner and 2 medial short flat setae; palp article 1, outer margin longer than inner, smooth; article 2, inner margin longer than outer, with 3 setulated setae on inner distal margin, 1 short simple seta on outer distal margin; article 3, 4 setulated setae on inner margin; article 4 rectangular, inner margin with 5 setulated distal setae and several fine setules, outer margin with 1 setulated seta. Epignath ( Fig. 1 View FIGURE 1 K) with blunt finely setose apex.

Cheliped ( Fig. 1 View FIGURE 1 L): Basis smooth, twice as long as wide. Merus ovoid, with 1 simple seta medially on ventral margin. Carpus oval, longer than basis, with 2 simple setae on ventral margin, 1 distal seta on dorsal margin. Propodus with row of serrated dorsal setae by dactylus insertion. Fixed finger with strong tip, 2 simple setae on ventral margin, 3 on cutting edge and 1 at dactylus insertion. Dactyl narrow, with 1 seta on its dorsal margin.

Oostegites: originating from pereonites 1­4.

Pereopod 1 ( Fig. 2 View FIGURE 2 A): Longer than other pereopods. Coxa with simple seta. Basis as long as combined length of 3 succeeding articles, smooth. Ischium with 2 simple setae on ventral margin. Merus longer than carpus, with 2 simple distal setae on ventral margin. Carpus with 3 simple distal setae. Propodus twice as long as long as carpus, tapering distally, with 3 simple distal seta. Dactyl and terminal spine not fused, together longer than propodus.

Pereopod 2 ( Fig. 2 View FIGURE 2 B): Similar to pereopod 1 except: Basis as long as combined length of 4 succeeding articles. Merus expanding distally, with 2 simple distal setae on ventral margin, shorter than carpus. Carpus with 2 simple setae on ventral margin. Propodus with 3 simple distal seta.

Pereopod 3 ( Fig. 2 View FIGURE 2 C): Similar to pereopod 2 except: Coxa smooth. Merus with 1 simple distal seta. Carpus marginally longer than merus, with 1 distal simple seta. Propodus with 2 simple distal setae.

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

Pereopod 5 ( Fig. 2 View FIGURE 2 E): As pereopod 4, except: Basis with 1 simple and 1 sensory setae on ventral margin. Ischium with 2 simple setae. Merus with few denticulated scales, 1 simple, 3 stout spiniform distal setae. Carpus as long as propodus with denticulated scales and 3 spiniform setulated distal setae.

Pereopod 6 ( Fig. 2 View FIGURE 2 F): As pereopod 5 except: Basis with 1 simple ventral seta. Merus as long as carpus, with 2 short stout distal setae. Propodus without sensory seta but with 3 stout setulated distal setae as long as dactylus.

Pleopods ( Fig. 2 View FIGURE 2 G): All 5 pairs similar. Protopod trapezoidal. Exopod armed with 19 plumose setae. Endopod, inner margin finely setose, with 15 plumose setae, 2 distal setae shorter and stouter than rest.

Uropods ( Fig. 2 View FIGURE 2 H): Protopod rectangular, with 1 simple seta. Endopod with incomplete fusion of articles, with 2 sensory setae midlength, 5 simple and 2 sensory distal setae. Exopod with 1 article, almost as long as endopod, with 1 simple seta midlength, 2 long simple distal setae.

Male: unknown

Etymology: Named for the cleaver­like ventral edge on article 2 of the antennal peduncle (Latin: Culter­formis = Cleaver­like).

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

Remarks: Bathytanais culterformis can be immediately distinguished from the other known members of the genus by the subquadrate shape of antennal article 2, which has blade­like, slightly concave, ventral margin produced into a relatively subacute distal process. The proximal ventral margin abruptly turns upward to the articulation with article 1, forming a subacute ventro­proximal process. Bathytanais culterformis , B. bipennifer and B. bathybrotes (as described by Lang, 1972) are the only known species of the genus to have both a dorsal and a ventral distal process on antennal article 3, but those on the two first species are acute and those on the latter are rounded or lobate. The other four species lack a dorsal process. The smooth ventral margin on the antenna article 2 ventral processes separates B. culterformis from B. bipennifer , which has a serrated margin.