Tanaella busteri, Drumm, David T. & Bird, Graham J., 2016

Drumm, David T. & Bird, Graham J., 2016, New deep-sea Paratanaoidea (Crustacea: Peracarida: Tanaidacea) from the northeastern Gulf of Mexico, Zootaxa 4154 (4), pp. 389-414 : 399-402

Tanaella busteri n. sp.

( Figs 6–9 )

Diagnosis. Male. Pereonites all wider than long, with rounded lateral margins. Pleonites with one pair of small setae on lateral margins. Pleotelson posterior half tapering to a rounded apex; longer than combined length of four pleonites. Antenna article-4 with fusion line. Maxillipedal endites with two pairs of setae. Cheliped fixed finger with inner serrate proximal depression. Pleopods with simple setae. Uropod longer than pleotelson; basal article less than half length of endopod; exopod represented only by two setae.

Female. Unknown.

Material examined. Holotype: ♂, 2.1 mm, ( USNM 1411517 ), northeastern Gulf of Mexico, App. Sed. 4, coll. F. Qu, 11 June 2014 . Paratypes: two ♂♂, 1.9–2.0 mm, (USNM 1411518), App. Sed. 7, coll. F. Qu, 11 June 2014; one manca-II, 1.0 mm, (USNM 1411 519), App. Sed. 3, coll. F. Qu, 11 June 2014.

Description. Adult male.

Body ( Fig. 6 A). Fairly slender, about 5.5 times as long as broad; length 1.9–2.1 mm (n = 3). Cephalothorax about 1.3 times as long as broad. Pereonites wider than long; pereonites 4 and 5 subequal and longest; pereonites 1 and 2 subequal and shortest; rounded lateral edges. Pleonites short and subequal, with one pair of short lateral setae on each pleonite. Pleotelson longer than combined length of four pleonites; posterior half tapering to a rounded apex.

Antennule ( Fig. 6 B) shorter than cephalothorax; article-1 longer than combined length of articles 2 and 3, about 2.5 times as long as wide, with subdistal simple seta and a PSS on outer margin; article-2 about 1.6 times as long as wide, with rounded outer margin and two subdistal PSS and subdistal finely setulate seta on outer margin; article-3 short, wider than broad, with dorsal simple seta, setulate seta and PSS on inner margin, outer margin spinulate; article-4 shorter than article two, with five simple setae and one aesthetasc. Antenna ( Fig. 6 C) with five apparent articles, article-1 presumed fused to cephalothorax; article-2 broader than following articles, naked, with seta on outer distal corner; article-3 short, with seta on inner distal corner; article-4 longer than other articles, with fusion line and three subdistal setae; article-5 subequal to article-3, with subdistal seta; article-6 minute, with three long simple setae.

Mouthparts. Left mandible ( Fig. 6 D) incisor with three denticles; lacinia mobilis nearly as long as incisor, with at least two denticles. Right mandible ( Fig. 6 E) incisor with three denticles; molar of both left and right mandibles broad and blunt, with about six apical spines. Labium ( Fig. 6 F) with each lobe spinulate on outer and distal margins. Maxillule ( Fig. 6 G–H) endite ( Fig. 6 G) with ten distal spiniform setae of which at least two are setulose; palp ( Fig. 6 H) with two distal unequal long setae. Maxilla ( Fig. 6 I) narrower at distal tip.

Maxilliped ( Fig. 6 J) basis fused, naked; endites with a distal process and two pairs of setae; palp article-1 naked; article-2 with three inner setae of which one is setulate and one outer seta; article-3 with two inner setulate setae and distal simple seta; article-4 with four inner setulate setae and subdistal simple seta.

Cheliped ( Fig. 7 A–B). Basis length subequal to carpus, posterior lobe larger than anterior mass, naked; merus triangular with one medioventral seta; carpus with two ventral setae and two dorsal setae (one proximal, one distal); propodus fixed finger with two ventral setae, three setae on dorsal face, and comb of three short and one long setulate setae on inner face, cutting edge with proximal serrated depression and four rounded denticles; dactylus naked, cutting edge smooth.

Pereopod-1 ( Fig. 7 C). Coxa with one simple seta; basis as long as combined length of ischium, merus, carpus, and half of propodus, with one dorsoproximal PSS; ischium with ventral seta; merus longer than carpus, with ventrodistal simple seta; carpus shorter than propodus, with one ventrodistal and one subdistal spiniform setae, and one dorsodistal simple seta; propodus longer than half of basis, ventral margin with double row of spinules, one ventrodistal spiniform seta, and one subdistal simple seta on dorsal margin; dactylus and unguis naked, together shorter than propodus.

Pereopod-2 ( Fig. 7 D). Similar to pereopod-1 except: merus shorter than carpus.

Pereopod-3 ( Fig. 7 E). Identical to pereopod-2.

Pereopod-4 ( Fig. 7 F) without coxa; basis as in pereopods 1–3; ischium with two ventral simple setae; merus shorter than carpus, with two ventrodistal simple setae; carpus with four distal spiniform setae; propodus with ventral row of spinules and three distal spiniform setae; dactylus with double row of spinules, with unguis longer than propodus.

Pereopod-5 ( Fig. 8 A) identical to pereopod-4.

Pereopod-6 ( Fig. 8 B). Similar to pereopods 4 and 5 except: carpus with three and propodus with four spiniform setae.

Pleopods ( Fig. 8 C). Basal article naked; exopod and endopod both with ten simple setae.

Uropod ( Figs 8 D, 9). Longer than pleotelson; basal article less than half length of endopod, with one long and one short distal simple seta on outer margin; endopod one-articled, with one subdistal and four distal simple setae, and three PSS; exopod vestigial, indicated by two setae.

Manca-II. Length 1.0 mm.

Female. Unknown.

Etymology. Named both for the senior author’s childhood pet dog (the uropods remind him of the way his back legs would sprawl out) and the inflatable crab that was stolen on the roof of Obadiah’s seafood restaurant in Marmora, New Jersey in 1996 —two loveable creatures that were taken way before their time.

Distribution. Northeastern Gulf of Mexico (offshore Alabama) at the depth range 2221–2289 m.

Remarks. This new species can be distinguished from the other two Gulf of Mexico species of Tanaella ( T. mclellandi and T. prolixcauda ) by the combination of two characteristics: 1) uropods longer than the pleotelson, and 2) pleotelson tapering posteriorly (at the level of the uropod attachment) to a rounded apex. It can further be distinguished from all other Tanaella by having the pleotelson longer than the combined length of four pleonites and all pereonites wider than long.

The assignment of ‘male’ status to these specimens is based on their possession of pleopods. Future collections of this species might alter this perception if mature specimens are found without pleopods.

Figures

FIGURE 6. Tanaella busteri n. sp., adult male. A, habitus (dorsal view); B, antennule; C, antenna; D, left mandible; E, right mandible; F, labium; G, maxillule endite; H, maxillule palp; I, maxilla; J, maxilliped. Scale bars: A = 0.5 mm; B = 0.1 mm; C, G, J = 0.05 mm; D – F, I = 0.03 mm.

FIGURE 7. Tanaella busteri n. sp., adult male. A, cheliped (outer); B, chela (inner); C, pereopod- 1; D, pereopod- 2; E, pereopod- 3; F, pereopod- 4. Scale bars = 0.1 mm.

FIGURE 8. Tanaella busteri n. sp., adult male. A, pereopod- 5; B, pereopod- 6; C, pleopod; D, uropod. Scale bars: A, B, D = 0.1 mm; C = 0.05 mm.