Atlantapseudes diversus ( Lang, 1968 )

Santos, Kátia Christol Dos & Hansknecht, Tom, 2007, Taraxapseudes n. gen., Taraxapseudes diversus (Lang, 1968) n. comb. and two new species of Atlantapseudes B cescu, 1978 (Tanaidacea: Apseudidae) from Brazil and Madagascar, with a key for the genus, Zootaxa 1639, pp. 23-39 : 26-29

Atlantapseudes diversus ( Lang, 1968) belongs to a new genus that is diagnosed here.

(also see Discussion)

Basin, Rio de Janeiro; Allotype male, 5.0 mm, MZUSP 17.975, 800 m, Sta. 0 23, same locality; Paratypes 1 immature male, MZUSP 17.943, 649 m, St. 334, Santos Basin, São Paulo; 1 manca, MZUSP 17.942, 1034 m, Sta. 110, same locality; 1 manca, MZUSP 17.944, 788 m, Sta. 0 19, same locality; 1 female without oostegites, MZUSP 17.945, 788 m, Sta. 0 20, same locality; 1 female with marsupium, MZUSP 17.946, 211 m, Sta. 0 59, same locality; 1 female damaged, MZUSP 17.947, 359 m, Sta. 0 75, Campos Basin, Rio de Janeiro; 1 female with marsupium - damaged, MZUSP 17.948, 970 m, Sta. 112, same locality; 1 manca, MZUSP 17.949, 870 m, Sta. 178, same locality.

Etymology. From the Latin, brasiliensis referring to collection locality.

Diagnosis. Pereonites 1 and 2 unarmed anteriorly; pereonites 3–6 with anterolateral spiniform processes, posterolateral curved spiniform processes on pereonites 1–3. Squama of antenna reaching the midpoint of third article, being 2.3 times the length of second article. Hyposphenia present both on pereon and pleon.

Female description. Body ( Figs. 1 a,b) 6.8 mm long, about 4.7 times longer than wide. Cephalothorax 0.8 times as long as wide, with lateral shoulders and acute rostrum; eye lobes present, without visual elements. Spine-like apophysis with naked borders is posterior to eye spines.

Pereonites all wider than long, with hyposphenia, 1–3 with acute lateral margins posteriorly; 3–6 bearing spiniform anteriolateral processes.

Pleonites 1–5 with hyposphenia, lateral pointed margins visible dorsally.

Pleotelson length-width ratio 0.8:0.7, widest at level of uropod attachment.

Antennule ( Fig. 1 c) article 1 approximately 3 times longer than second, bearing unequal setae on both margins; article 2 with one long seta distally on outer and simple setae on inner margin; article 3 shorter than wide with single distal seta on each margin; inner flagellum with three, outer with seven articles.

Antenna ( Fig. 1 d) composed of eleven articles, all of them bearing setae; article two with inner and outer setae, and with elongate squama, reaching nearly ¾ level of article 4. Squama with two terminal setae. Articles 2 and 4 of same length, approximately 3 times longer than article 3; article 5 longest.

Labrum ( Fig.1 e) covered with fine setules on both margins.

Mandibles pars molaris and incisor with irregular cutting edge, left mandible ( Fig. 1 f) incisor and lacinia mobilis with four dentate processes; one serrate and four spiniferous setae. Right mandible ( Fig. 1 g) with lacinia mobilis reduced and trifurcate, three spiniferous setae. Palp ( Fig. 1 h) three-articled, first article bearing one simple seta at midlength on inner margin, second article about 2.5 times longer than first, with four setae distally, third article bearing seven setae on inner margin.

Labium ( Fig. 1 i) with oval base lobe, setose on inner and outer margins; palp covered with fine setules, bearing three spine-like setae distally.

Maxillula ( Fig. 2 a) outer endite with eleven terminal and two subterminal setae. Inner endite bearing two circumplumose and one simple setae; both outer margins finely setose; palp two-articled, with three setae armed distally with fine, recurved setules.

Maxilla ( Fig. 2 b) movable endite, inner lobe with four plumose and one simple setae; outer with four simple setae. Fixed endite, inner comb row with numerous basally – inflated setae, outer with four furcated setae, one partially pinnate and two simple setae.

Maxilliped ( Fig. 2 c) basis simple, with only one seta; first palp article trapezoidal in shape with outer distal and inner proximal setae; second palp article largest with eight setae on inner margin and one on outer margin; third palp article about ½ length of second with inner margins bearing nine setae each; last palp article with several terminal setae. Endite with two coupling hooks, distal margin of inner side with five palmate and two circumplumose setae subterminally; outer margin with setules.

Epignath ( Fig. 2 d) margin and lobes naked; terminal seta with setules distally.

Cheliped ( Fig. 2 e) exopod absent; basis twice as long as broad, spiniform seta ventral on posterodistal third; fused ischium-merus with one short simple seta on ventral margin; carpus about ¾ the length of basis, with two simple setae ventrally; propodus and fixed finger combined about twice longer than carpus, three simple setae on ventral margin, and six setae near cutting margin; dactylus with cluster of setae near midpoint; unguis with smooth cutting margins.

TABLE.2. Comparative Atlantapseudes species.

Character A. brasiliensis sp.nov. A. cyanea A. lindae A.madagascariensis A. nigrichela Bamber, 2007 Meyer & Heard, sp.nov. Băcescu, 1978 1989

Sexual dimorphism

Chela Not observed (*) Not observed Present Only male known Not observed

(**) (**)

Antennule Present Not observed Present Not observed

(**) (**) Pereopod 1 ( Fig. 3 a) exopod absent. Basis longer than ischium, merus and carpus combined, about 5 times longer than wide, with one medial and one ventrodistal setae, one broom seta dorsal near midpoint; merus with four long setae near midpoint, one cuspidate and two simple setae ventrodistally, three setae dorsodistally; carpus with several setae on both margins, two spines ventrodistal and one dorsodistal, two short spiniform setae subterminally; propodus with two spines dorsal and five ventral, increasing distally in length; dactylus with two proximal setae on dorsal margin and two ventromedial spines and a ventrodistal spine projecting beneath unguis; unguis about ½ length of dactylus.

Pereopod 2 ( Fig. 3 b) basis smaller than combined length of merus, carpus and propodus with three short setae ventrally; ischium bearing one ventral seta; merus with two proximal and four distal setae ventrally, margin dorsal with two distal setae; carpus almost as long as propodus, with five dorsal, three ventral and three terminal setae; propodus dorsal margin with four simple setae and one spine terminally; four spines ventrally with simple setae between them; dactylus longer than all previous articles, except basis.

Pereopod 3 ( Fig. 3 c) basis subequal to combined length of merus, carpus and propodus, with one small setae at midlength ventrally; ischium with one ventral seta. Merus with one distal seta dorsally, one at the proximal half and three distal simple setae ventrally; carpus with four setae dorsal, two simple and one cuspidate at distal half ventrally and two long setae terminally; propodus same length as carpus with two simple and two cuspidate seta dorsally, two cuspidate and one simple seta ventrally; dactylus same length of merus.

Pereopod 4 ( Fig. 3 d) basis like pereopod 3; merus with one simple dorsodistal and two spines ventrodistal; carpus with a row of six spines ventroterminally; propodus rectangular, with one large broom seta near midpoint dorsally, one short cuspidate at opposite position of broom setae and a row of unequal simple setae terminally; dactylus shorter than propodus.

Pereopod 5 and 6 ( Fig. 3 e,f) similar. Basis longer than combined length of merus, carpus and propodus, with one seta at half ventrodistal margin; merus with one cuspidate seta ventrodistal; carpus longer than merus or propodus, with one cuspidate seta dorsodistal; propodus pereopod 5 with one long cuspidate seta at mid length and a smaller one distally, four setae ventrally; pereopod 6 with one cuspidate seta at mid length and four simple setae ventrally; both pereopods 5 and 6 with long spiniform setae terminally on dorsal margin; dactylus almost the same length as carpus.

Pleopods absent.

Uropod ( Fig. 3 h) exopod five-articulate, last article with three long terminal setae; endopod with 10–20 articles due to large number of fusions resulting in pseudo-articles; last article with three terminal setae.

Sexual dimorphism. Cheliped not studied (broken). Pleopod ( Fig. 3 g) basal article naked, almost same endopod length; endopod and exopod bearing several long plumose setae.

Remarks. The ornamentation for the anterolateral margins of pereonites is unique in the new species, differing from the other five known species. The pereonites 1 and 2 are unarmed anteriorly as in A. cyanea , A. lindae , A. madagascariensis sp. nov. and A. nigrichela , but have posterolateral curved spiniform processes on pereonites 1–3, which are absent in the other four species. The relative lengths of squama and the third article of the antenna is an important feature to compare Atlantapseudes species. Atlantapseudes brasiliensis sp. nov. has the squama reaching the midpoint of the third article. Hence, in the new species the length is 2.3 times the length of the second article. This size relationship differs from those in all five known species.

The new species also bears hyposphenia on pereonites as in A. madagascariensis sp. nov. and on pleonites as in A. nigrichela . The setation on the carpus of the cheliped is similar to the situation in A. cyanea , A. madagascariensis n. sp. and A. lindae . The setation on the fixed finger is as in A. nigrichela .

Figures

FIGURE 1. Atlantapseudes brasiliensis sp. nov. Female (6.8 mm). (a) dorsal view; (b) lateral view; (c) antennule; (d) antenna; (e) labrum; mandible (f) left, (g) right, (h) palp; (i) labium.

FIGURE 2. Atlantapseudes brasiliensis sp. nov. Female (a) maxilla 1; (b) maxilla 2; (c) maxilliped; (d) epignath; (e) cheliped.

FIGURE 3. Atlantapseudes brasiliensis sp. nov. Female (a) pereopod 1; (b) pereopod 2; (c) pereopod 3; (d) pereopod 4; (e) pereopod 5; (f) pereopod 6; (g) uropod. Male (h) pleopod.