Neotanais rotermundiae, Weigmann, Simon & Guerrero-Kommritz, Jürgen, 2009

Weigmann, Simon & Guerrero-Kommritz, Jürgen, 2009, New species of Neotanais Beddard, 1886 (Crustacea, Tanaidacea) from the deep sea of the tropical and southern East Atlantic Ocean, Zootaxa 1992, pp. 20-36 : 21-28

Neotanais rotermundiae sp. n.

( Figures 2 to 4)

Material examined: 18 individuals. Holotype ZMH K- 42019, RV Meteor 63-2, St. 63, one female. Paratypes ZMH K- 42020, RV Meteor 63-2, St. 63, one manca I, one manca II, five neuters, one female, one male, ZMUC-CRU-20152 RV Meteor 63-2, St. 64, one manca I, one neuter, one female, ZMH K- 42021, RV Meteor 63-2, St. 84, one neuter, ZMH K- 42022, RV Meteor 63-2 St. 89, one manca I, one manca II, ZMH K- 42023, RV Meteor 63-2, St. 90, two females.

Other material examined: Neotanais americanus Beddard, 1886 . ZMUC-CRU-9960, Ingolf, St. 22, 3474 m, one manca II, one neuter. ZMUC-CRU-9961, Eastward, St. 20096, one female, one male. ZMUC- CRU-9962, WHOI, benthic St. 63, 2891 m, two manca I, two neuters, one female.

Diagnosis: female. Chela with high dorsal crest. Pereopods 4 to 6 with a bilobated serrated terminal shield on dactylus. Dactylus and ungius of pereopods 4 to 6 with a ventral double row of spinules. Pleon with ventral projections. Pleotelson pentagonal, not acornshaped. Uropods inserted ventrally. Uropod’s endopod with up to 15 articles.

Description: non-ovigerous female.

Body ( Fig. 2 A, B): long and slender, nine times as long as wide, dorsoventrally flattened.

Cephalothorax ( Fig. 2 A, B): 1.5 times as long as wide, anterior end tapering to the antennulae, comprising 0.18 of body length.

Pereon ( Fig. 2 A, B): composed of six free pereonites, comprising 0.57 of body length; pereopods laterally attached; pereonite 1 shortest, triangular on dorsal view, 1.7 times wider than long; pereonites 2 to 6 rectangular; pereonites 2 to 5 as wide as long; pereonite 5 longest; pereonite 6 shorter than 2 and longer than 1.

Pleon ( Fig. 2 A, B): comprising 0.25 of body length, composed of five free pleonites and a pleotelson; all pleonites of almost equal length and with a ventral conical blunt projection; pleotelson pentagonal and without setae; uropods inserted ventrally.

Antennula ( Fig. 2 F): composed of seven articles. Article 1 longest, longer than the other articles of the antennula together, 2.7 times as long as wide, with two broom setae proximoventrally and several setules near insertion of body; distal third with five simple setae, one long, two middle and two short ones and four broom setae, three lateral and one ventral. Article 2 one and a half times as long as wide, with a short distodorsal simple seta, two ventral simple setae, one long and one middle, and a distolateral row of four broom setae, perpendicular to antennula axis. Article 3 almost square, with one short simple seta distoventrally and one serrated seta and two broom setae distodorsally. Article 4 three times as long as wide, without setae. Article 5 twice as long as wide, with one terminal multiarticulated aesthetasc and a terminal short simple seta. Article 6 three times as long as wide, with one terminal multiarticulated aesthetasc and a terminal short simple seta. Article 7 three times as long as wide, with four terminal short simple setae.

Antenna ( Fig. 2 E): composed of nine articles. Article 1 short, 1.5 times as long as wide, without setae. Article 2 longest, three times as long as wide, with one long simple seta dorsally. Article 3 almost square, with one simple seta dorsally. Articles 4 to 7 twice as long as wide. Article 4 without setae. Article 5 with two broom setae distoventrally and two plumose and three long simple setae distally. Article 6 with two short distal simple setae. Article 7 with three short simple setae distally. Article 8 three times as long as wide, without setae. Article 9 twice as long as wide, with one short dorsal and three terminal simple setae.

Labrum ( Fig. 3 C): hoodlike, tubular, distally slightly pointed with several setules on inner surface. Inner part of the oesophagus visible ( Fig. 3 D): semitubular, with a row of two simple and four serrate setae at the edge of each external margin; upper internal margin with nine bifurcated spiniform setae distally and a row of simple setae at the edges; lateral inner margins each with one row of simple setae.

Mandibles ( Fig. 3 A, B): pars incisiva of left mandible with two teeth; lacina mobilis with two teeth, two bipinnate setae and a simple seta; pars molaris long with three small protuberances and a simple seta at its base. Pars incisiva of right mandible with a sharp cutting edge; lacina mobilis with one blunt bipinnate seta and two bipinnate setae; pars molaris with three protuberances and a simple seta at its base.

Maxillula ( Fig. 3 G): composed of two endites. Outer endite distally with nine setae, one short and seven long spiniform setae and one long serrated seta, as well as several setules on outer margin. Inner endite with one long setulose seta and three simple setae, outer margin with several setules.

Maxilla ( Fig. 3 F): basis with several comb setae. Inner lobe of fixed endite with one simple and ten hooked setae. Outer lobe with two bifurcated spiniform setae, one bipinnate and one long and four short simple setae. Inner lobe of movable endite with two plumose and one short and two long simple setae. Outer lobe with three long simple setae.

Labium ( Fig. 3 E): basal plate with inner lobes. Left lobe with two short simple setae and several setules. Right lobe only with long setules. Palps elongated with several setules.

Maxilliped ( Fig. 3 H, I): basis not fused, broad, with one to two basal simple setae. Endite’s inner margin with two setulose setae, a row of setules and terminally one simple, one setulose and five spiniform setae. Palp, article 1 widening distally with one medial simple seta on inner margin. Article 2 with five to six bipinnate setae on inner and one bipinnate seta on outer margin. Article 3 with five to six bipinnate setae on inner margin. Article 4 with two lateral and five distal bipinnate setae. However on the drawing most setae are illustrated simple.

Epignath: not recovered, lost during dissection.

Cheliped ( Fig. 2 C): basis spherical, about 0.8 times as long as chela. Ischium slender. Merus triangular with one ventral simple seta. Carpus twice as long as wide, with two ventral simple setae and a row of twelve simple setae dorsally. Propodus smooth, twice as long as dactylus, with a high and sharp crest dorsally; fixed finger with two distoventral and three dorsal simple setae and one simple seta at the basis of dactylus insertion; cutting edge with a proximal serrated part and five distal teeth. Dactylus dorsally slightly serrated and with one proximal bipinnate seta, as well as one bipinnate seta at the dorsal insertion of dactylus and a ventral spiniform process.

Pereopod 1 ( Fig. 4 A): coxa simple. Basis long, about as long as merus and carpus together, with one ventral and two dorsal short simple setae, as well as one ventral broom seta. Ischium with one short and one middle simple seta. Merus with three bipinnate setae. Carpus laterally with one row of five and one row of six slender and long bipinnate setae, as well as one middle and one short bipinnate seta terminally. Propodus laterally with two rows of three bipinnate setae each; also with one terminal grooming seta with five ventral teeth and a row of setules dorsally. Dactylus with one ventral short simple seta. Ungius without setae, about half as long as dactylus. Details of propodus, dactylus and ungius in figure 4 B.

Pereopod 2 ( Fig. 4 C): coxa simple. Basis four times as long as wide, with one dorsal and one ventral short simple seta. Ischium with two simple setae. Merus twice as long as wide, with one ventral bipinnate seta. Carpus laterally with one row of five and one row of six slender and long bipinnate setae and one short terminal bipinnate seta. Propodus laterally with one row of five and one row of four slender and long bipinnate setae, one terminal bipinnate and one terminal grooming seta with five ventral teeth and a row of setules dorsally. Dactylus slightly serrated and with one row of minute spinules. Ungius without setae, about half as long as dactylus.

Pereopod 3 ( Fig. 4 D): coxa simple, with one short simple seta. Basis with one dorsal and one ventral broom seta. Ischium with one simple seta. Merus with two bipinnate setae. Carpus laterally with one row of five and one row of six slender and long bipinnate setae and one short terminal bipinnate seta. Propodus laterally with one row of five and one row of four slender and long bipinnate setae, one terminal bipinnate and one terminal grooming seta with five ventral teeth and a row of dorsal setules. Dactylus with one short terminal simple seta. Ungius without setae, about half as long as dactylus.

Pereopod 4 ( Fig. 4 E): coxa simple. Basis three and a half times longer than wide, without setae. Ischium without setae. Merus twice as long as wide, with three bipinnate setae; carpus with two lateral rows of five bipinnate setae each and one simple terminal seta. Propodus with seven distal bipinnate setae. Dactylus with one short simple seta and a bilobated and finely serrated terminal shield, which passes laterally into two rows of spinules. Ungius about 0.75 times as long as dactylus, with two rows of ventral spinules.

Pereopod 5 ( Fig. 4 F): coxa simple. Basis about four times as long as wide, proximally with one tubular and one broom seta. Ischium with two simple setae. Merus twice as long as wide, with three bipinnate setae. Carpus laterally with one row of four and one row of five bipinnate setae and one terminal simple seta. Propodus with seven distal bipinnate setae. Dactylus and ungius as in pereopod 4. For details of dactylus and ungius see figure 4 G.

Pereopod 6 ( Fig. 4 H): similar to pereopod 4, but carpus with four bipinnate setae per row; propodus distally with seven bipinnate and one row of four spiniform setae. Dactylus as in Pereopod 4, unless it is serrated and with one short simple seta. Ungius about 0.8 times as long as dactylus, with two ventral rows of spinules.

Pleopod ( Fig. 3 J): all pairs similar. Basal article longer than wide, with one dorsal and two ventral plumose setae. Exopod with two dorsal and 13 distal plumose setae. Endopod with three dorsal, three ventral and ten distal plumose setae.

Uropod ( Fig. 2 D): basal article about twice as long as wide, without setae. Exopod composed of two articles, about 0.8 times the length of endopod’s article 1. Article 1 with one simple seta. Article 2 with two terminal simple setae. Endopod composed of 14 articles. Article 1 as long as article 2 and twice as long as wide, without setae. Article 2 as long as the first, distally with one simple and two broom setae. Article 3 almost square and half as long as article 2, with one distal simple seta. Article 4 as long as article 2, with one simple and three broom setae distally. Article 5 as long as article 3, with one distal simple seta. Article 6 longer than article 2, distally with two simple and three broom setae. Article 7 as long as article 3, with one distal simple seta. Article 8 as long as article 6, with two simple and three broom setae distally. Article 9 as long as article 3, with one distal simple seta. Article 10 as long as article 6, distally with two simple and three broom setae. Article 11 as long as article 3, with one distal simple seta. Article 12 longer than article 3 but shorter than 2, with two simple and two broom setae distally. Article 13 as long as article 3, with one distal simple seta. Article 14 as long as article 2, with five terminal simple setae and one terminal broom seta.

Neuter: like non-ovigerous female, without oostegites.

Male: only one damaged individual, chelipeds are missing. Cephalotorax longer, pleonites broader and pleopods larger than in females. Pereonites with strong shoulders. A special finding are rudimental oostegites on pereopods 1 to 4.

Manca I: up to 2.6 mm.

Manca II: between 3.1 and 3.5 mm.

Type locality: South Atlantic Ocean, Guinea Basin, RV Meteor 63-2, St. 63, 0°7.1'S 002°28.9'W – 0°8.2'S 002°28.7'W, 5060 m.

Etymology: the name is dedicated to Natalie Rotermund, the fiancée of the first author.

Distribution: deep sea of the tropical East Atlantic Ocean: Guinea Basin.

Remarks: oostegites are present on the first four pereopods, as shown in figures 4 A, C, D, E. No ovigerous female was observed, that is why the shape of fully developed oostegites is still unknown. The only male is damaged and the chelipeds are missing. A special character of this male is that it has rudimental oostegites. Neotanais rotermundiae can be distinguished from all other species of Neotanais because of the elongated and finely serrated bilobated shield on the dactylus of pereopods 4 to 6. The serration of these shields is very fine with many and minute teeth. All other described species of Neotanais with similar shields have shields with only few large and broad teeth. The chela of Neotanais rotermundiae has a dorsal crest which has a foreward pointed projection building an acute angle to the dactylus. The uropod’s endopod has up to 15 articles and many broom setae. This is an unusual observation among all described species of Neotanais , because all species of Neotanais with a similar high number of endopod articles only have few broom setae on all articles. The only species with a similar amount of broom setae is Neotanais americanus Beddard, 1886 , whose uropod’s endopod is composed of only nine articles. But the broom setae are very fragile and easily lost, that is why this is an unrealiable character. Article 2 of the antennula of Neotanais rotermundiae has a distolateral row of four broom setae, perpendicular to antennula axis. Only N. bacescui Lang, 1968 has a similar row of broom setae on this article but with five setae. The grooming seta on pereopods 1 to 3 has a dorsal row of setules, which has not been described for any other species of Neotanais .

Figures

FIGURE 2. Neotanais rotermundiae, A – B. Female holotype, ZMH K- 42019 A. Body, dorsal view, B. Body, lateral view. Scale bar 2 mm. C – F. Female Paratype, ZMH K- 42023. C. Cheliped, D. Uropod, E. Antenna, F. Antennula. Scale bars 0, 5 mm.

FIGURE 3. Neotanais rotermundiae, female paratype, ZMH K- 42023 A. Left mandible, B. Right mandible, C. Labrum, D. Oesophagus, E. Labium, F. Maxilla, G. Maxillula, H. Maxilliped 1, I. Maxilliped 2. Scale bar 0, 2 mm. J. Pleopod 1. Scale bar 0, 5 mm.

FIGURE 4. Neotanais rotermundiae, female paratype, ZMH K- 42023 A. Pereopod 1, B. Detail of pereopod 1, C. Pereopod 2, D. Pereopod 3, E. Pereopod 4, F. Pereopod 5, G. Detail of pereopod 5, H. Pereopod 6. Scale bar 0, 5 mm.