Tanaella profunda, Guerrero-Kommritz, Jürgen & Blażewicz-Paszkowycz, Magdalena, 2004

Guerrero-Kommritz, Jürgen & Blażewicz-Paszkowycz, Magdalena, 2004, New species of Ta n a e l l a Norman and Stebbing, 1886 (Crustacea: Tanaidacea: Tanaellidae) from the deep­sea off the Antarctic and the Angola Basin, with a key to the genus, Zootaxa 459, pp. 1-20 : 15-19

Tanaella profunda sp. nov. ( Figs. 7­9 )

Material examined: holotype: ZMH K­ 40299, DIVA station. 336, 18° 16.6’S; 004° 44.5’E, KG, 5395 m, July 2000, preparatory male, 2.35 mm. Paratypes: ZMH K­ 40300, DIVA station 345, 16° 17.0’S 005° 27.1’E, KG, 5390 m, 26 July 2000, preparatory male, 2.35mm, (dissected), ZMH K­ 40301, DIVA station 320, 22° 17.9’S 003° 17.2’E – 22°20.0’S 003° 17.9`E, EBS, 5180 m, 10 July 2000, adult female, 2.75 mm, ZMH K­ 40302, DIVA station 345, 16°17.0’S 005°27.1’E, KG, 5390 m, 26 July 2000, manca II, 1.86 mm, ZMH K­ 40303, DIVA station 348, 16°17.1’S 005°27.3’E – 16° 19.3’S 005° 27.2’E, EBS, 5390 m, 28 July 2000, manca II, 1.46 mm, ZMH K­ 40304, DIVA station 325, 19° 58.2’S 002° 51.8`E, Muc, 5447 m, 14 July 2000, manca I, 1.36 mm.

Diagnosis: cheliped massive, basis and dactylus with combs of setae and without proximal process in inner margin of dactylus. Maxilliped endites with tubercle. Pereopods 4­6 with ventral margin of propodus serrated. Uropod longer than pleotelson, composed of uni­articled endopod; basal article naked, shorter than half of endopod. Male pleopods without plumose setae.

Description: preparatory male. Body ( Fig. 7 a, b) about six and a half times longer than broad, dorsoventrally flattened.

Cephalothorax ( Fig. 7 a, c) triangular, shorter than pleon, posterior end 1.8 times broader then anterior end.

Pereon, first pereonite shortest, second and sixth equal in length, third and fifth pereonites equal in length, fourth pereonite longest.

Pleon as wide as pereon, pleonites of equal length. Pleotelson pentagonal, as long as last three pleonites combined, apex rounded.

Antennula ( Fig. 8 a) four­articled. First article little longer than articles 2–4 combined, with many comb setae on proximal end, and one simple seta subdistally. Second article with two setulose and one simple setae subdistally. Third article shortest with two simple setae and one comb seta. Fourth article twice as long as third, tipped with one aesthetasc, six long and one short simple setae.

Antenna ( Fig. 8 b) six­articled. First article short nearly fused with the cephalothorax (not drawn). Second article as long as broad, with three long comb setae dorsally and one distal seta. Third article short with one distal simple seta. Fourth article twice as long as fifth, with five simple distal setae (two long, one short and two minute). Fifth article with two terminal simple setae. Sixth article shortest with three long and one subterminal setae.

Mouthparts: Labrum ( Fig. 8 c) hood­like, distal margin with two rows of setules. Mandible ( Fig. 8 d, e) right mandible incisor pointed with three teeth; left mandible incisor blunt teeth, lacinia mobilis pointed; seven terminal teeth on the molar process. Maxillula ( Fig. 8 f) endite with four ventral comb setae and nine distal setae (three bipinnate, five simple and a small one). Maxilla ( Fig. 8 g) triangular. Labium (not drawn, destroyed during dissection) composed of two triangular lobes. One short spiniform seta and many setules on apical margin. Maxilliped ( Fig. 8 i) basis fused. Endites with a tubercle on the distal margin. Palp four­articled. First article with a comb seta and one simple strong outer seta. Second article with three inner strong setae. Third article with a comb seta two strong and two thin inner setae. Fourth article with a comb seta and four strong and one thin terminal setae. Epignath not recovered.

Cheliped ( Fig. 8 h, h’) attached to cephalothorax by sidepiece, basis strong with eight comb setae on the posterior ventral margin. Merus with one simple ventral seta. Carpus with three comb setae on the posterior dorsal margin one dorsal seta near insertion of propodus and two simple setae ventrally and one tubercle at the insertion with propodus. Propodus twice as long as broad, fixed finger with two ventral setae and three setae near cutting edge. Cutting edge composed of five blunt teeth. Dactylus smooth with two short strong setae at cutting edge. Inner side of dactylus with many comb setae. Propodus with one long pinnate strong seta and two simple setae at insertion of dactylus.

Pereopod 1 ( Fig. 9 a) coxa with seta. Basis as long as ischium, merus carpus and half of propodus combined length, with a row of setules dorsally. Ischium short, with one simple seta. Merus subequal in length to carpus with one strong distal seta. Carpus with three comb seta ventrally and two long and one short strong distal setae. Propodus slightly longer than dactylus and unguis combined, with two rows of spinules and one strong seta ventrally, a row of setules and one dorsal thin seta dorsally. Dactylus as long as unguis.

Pereopod 2 ( Fig. 9 b) as pereopod 1, except basis lacks setules, and carpus is without comb setae and propodus without dorsal setules.

Pereopod 3 ( Fig. 9 c) as pereopod 2, except basis with one setulose seta at midlength.

Pereopod 4 ( Fig. 9 d) coxa absent. Proportion of articles as in pereopod 1except carpus slightly longer than merus; shorter than dactylus and unguis combined. Basis naked. Ischium short with relatively long simple seta. Merus with two distal setae. Carpus with two ventral comb setae and four strong distal setae. Propodus with two rows of spinules ventrally and three distal setae. Dactylus with a ventral groove bordered by fine spinules.

Pereopod 5 ( Fig. 9 e) as pereopod 4, except one extra simple short distal seta on carpus.

Pereopod 6 ( Fig. 9 f) as pereopod 5, except carpus with only three long strong setae.

Pleopods ( Fig. 9 h). Basal article rectangular shape. Endopod and exopod uni­articulate with some notches on distal margins.

Uropods ( Fig. 9 g) uniramous. Basal article longer than broad, naked. Endopod with uni­articulate; tipped by three long simple setae two setulose setae and one short simple seta and subdistally with two long simple and two setulose setae.

Females: similar to preparatory male but lack pleopods.

Manca I: as neuter except pereonite six is not developed, and the size is smaller (1.36 mm).

Manca II: T186 1.46–1.86 mm as neuter except pereonite six is developed and pereopod 6 resembles a backwards projected spine.

Etymology: named in reference to the deep­sea habitat in which this species was found.

Remarks: Larsen and Heard (2004) mentioned that the males of Tanaella should have pleopods, and that the antennula should be thicker than those of females and neuter specimens. However, the pleopods on a specimen examined in this study lacked setae, and this specimen was assumed to be a preparatory male, because adult males have pleopods with setae and thicker antennula. Furthermore, the morphology of the antennula in this specimen provides no additional characters to help differentiate it from other specimens or taxa. No genital cones were observed.

Tanaella profunda resembles Tanaella prolixcauda Larsen & Heard 2004 but the species can be separated by the proportions of the pereonites: pereonite one is shortest followed by the second and sixth and pereonite four is longest in T. profunda . However in T. prolixcauda pereonite one is equal in length to pereonite six, and the second pereonite is shorter than third, while the third, fourth and fifth are equal in length and represent the longest pereonites. Pereopod 1 in T. profunda has one seta on the basis and one seta on the carpus while the basis of T. prolixcauda lacks setae and has 2 setae on the carpus.

According to Larsen and Heard (2004) the bathymetric distribution of Tanaella is from 44 to 4800 m. Tanaella profunda was found in very deep habitats (4950–5450 m) expanding the bathymetric distribution of the genus.

Figures

FIGURE 7. Tanaella profunda sp. nov., holotype (preparatory male): a, dorsal view. b, lateral view. c, ventral view of cephalothorax. Scale bar = 1 mm

FIGURE 8. Tanaella profunda sp. nov., paratype (preparatory male): a, antennula. b, antenna. c, labrum. d, e, mandible; f, maxilla; g, maxillula; i, maxilliped; h, h’, cheliped. Scale bar = 0.1 mm

FIGURE 9. Tanaella profunda sp. nov., paratype (preparatory male): a, pereopod 1; b, pereopod 2; c, pereopod 3; d, pereopod 4; e, pereopod 5; f, pereopod 6; g, uropod; h, pleopods (male). Scale bar = 0.1 mm.