Collettea bamberi, 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 : 392-397

Collettea bamberi n. sp.

( Figs 2–5)

Diagnosis. Female. Pereonites 1–3 short (about 3 times as wide as long), subequal (almost equal) in length (only slightly increasing in length posteriorly). All pereonites wider than long. Pleotelson long, at least as long as four pleonites combined. Antenna article-4 without fusion line, about 4.5 times as long as broad. Maxilliped endite with two pairs of setae. Cheliped fixed finger with one ventral seta. Uropods short, less than ¼ length of pleotelson; endopod 2-articled.

Male. Known only from abdomen. Pleopods without setae.

Material examined. Holotype: female (♀), 2.8 mm, ( USNM 1411512 ), Northeastern Gulf of Mexico, App. Sed. 1, collected (coll.) by F. Qu, 12 June 2014.

Paratypes: two ♀♀, 2.3–2.5 mm, (USNM 1411513), App. Sed. 4, coll. F. Qu, 11 June 2014; one ♀, 2.3 mm, (USNM 1411514), App. Sed. 5, coll. F. Qu, 11 June 2014; one male (♂) (abdomen only, USNM 1411515), App. Sed. 10, coll. F. Qu, 10 June 2014; three ♀♀, 1.1–2.0 mm, (USNM 1411516), App. Sed. 12, coll. F. Qu, 10 June 2014.

Description. Adult female. Holotype: ( Figs 2, 3 A). Paratype: ( Figs 3 B–5F). Body ( Figs 2, 3 A) slender, about 7.2 times as long as wide; length 1.1–2.8 mm (n = 7). Cephalothorax longer than wide; as long as combined length of pereonites 1–3. Pereonites 1–3 short and subequal; pereonite-5 longest. All pereonites wider than long, with gently rounded lateral margins. Pleonites all subequal. Pleotelson as long as four pleonites combined.

Antennule ( Fig. 3 C) with four articles, without cap-like terminal segment, slightly shorter than cephalothorax; article-1 longer than rest of antennule combined, with one subdistal simple seta and several PSS on outer margin; article-2 longer than article-3 and shorter than article-4, with simple seta and several PSS on outer margin; article-3 with two subdistal simple setae; article-4 less than half length of article-1, with five distal simple setae, one distal aesthetasc, and one distal PSS on outer margin.

Antenna ( Fig. 3 D) slightly shorter than antennule, with six articles; article-1 fused to body, naked; article-2 longer than article-3, with distal seta; article-3 with distal seta; article-4 more than 4 times as long as broad, without ‘fusion line’, with subdistal simple seta and several PSS; article-5 as long as article-2, with long subdistal seta; article-6 minute, with two short and three long simple setae.

Mouthparts. Labrum and labium not recovered. Left mandible ( Fig. 3 E) incisor with three denticles; lacinia mobilis as long as incisor; molar broad, with group of small spines. Right mandible ( Fig. 3 F) incisor with three denticles; molar as in left mandible. Maxillule ( Fig. 3 G) endite with six or seven long setae and two shorter setae; palp not recovered. Maxilla ( Fig. 3 H) broader at base.

Maxilliped ( Fig. 3 I) bases fused, with patch of densely-packed setules on ventral surface giving a felt-like appearance; endites narrower than basis, slightly flared, each with two blunt distal processes and a pair of simple setae; palp article-1 naked; article-2 with three inner setae; article-3 with three setae; article-4 narrow, with five terminal and one subdistal seta.

Cheliped ( Fig. 4 A–B). Basis with triangular, isolated sclerite attached dorsally, posterior lobe reaching pereonite-1, naked; merus triangular, with one ventromedial seta; carpus 1.9 times as long as broad, shorter than propodus including fixed finger, with proximal and distal dorsal seta; propodus with long diagonal row of setules on inner face and long pectinate distal seta; fixed finger with ventral seta, seta on outer surface, and two setae on inner surface, cutting edge with three distal denticulations; dactylus with four short and one longer seta on proximal inner surface.

Pereopod-1 ( Fig. 4 C). Coxa with seta (not illustrated); basis as long as combined length of ischium, merus, carpus, and half of propodus, naked, widening distally; ischium naked; merus shorter than carpus, widening distally, with ventrodistal seta; carpus ¾ length of propodus, with three distal spiniform setae; propodus half as long as basis, with two subdistal spiniform setae; dactylus slightly shorter than unguis and combined longer than propodus; unguis flared near tip.

Pereopod-2 ( Fig. 4 D). Similar to pereopod-1 but propodus without dorsodistal spiniform seta.

Pereopod-3 ( Fig. 4 E). Identical to pereopod 2.

Pereopod-4 ( Fig. 4 F). Coxa with seta (not illustrated); basis as long as combined length of ischium, merus, carpus, and propodus, with one PSS on dorsal margin; ischium with seta; merus subequal to carpus, with two pectinate spiniform setae; carpus with four pectinate spiniform setae; propodus with two long pectinate spiniform setae and two shorter dorsodistal spiniform setae; dactylus longer than unguis, with spinules at base; unguis setulate; dactylus and unguis combined longer than propodus.

Pereopods 5–6 ( Fig. 5 A–B) identical to pereopod-4.

Pleopods absent.

Uropod ( Figs 3 A–B; 5C). Short (just protruding beyond apex of pleotelson); basal article longer than endopod first article, naked; endopod two-articled, article-1 naked, article-2 half as long as first article, with six simple and one PSS; exopod minute, less than half length of endopod article-1, with one long and one short simple seta.

Male. Known only from pleon. Pleopods ( Fig. 5 D) without setae.

Etymology. Named in honor of the late Roger Bamber for his significant contribution to tanaidacean systematics.

Distribution. Northeastern Gulf of Mexico (offshore Alabama) at the depth range 2202–2289 m.

Remarks. Collettea bamberi n. sp. can be distinguished from its congeners by the following combination of characteristics: 1) pereonites 1–3 short and subequal in length (only slightly increasing in length posteriorly), 2) pleotelson at least as long as four pleonites combined length, and 3) cheliped fixed finger with one ventral seta. It can easily be distinguished from the other two GOM species of Collettea ( C. elongata and Collettea sp. A sensu Larsen, 2005) by the short and subequal pereonites 1–3.

Pereopods 4 and 5 of a smaller paratype female ( Fig. 5 E–F) differed from the described paratype female by having the basis shorter than the combined length of the ischium, merus, carpus, and propodus, and by having only three pectinate setae on the carpus. The incomplete male here is almost certainly juvenile or ‘preparatory’ (sensu Gardiner 1975).

Figures

FIGURE 3. Collettea bamberi n. sp., adult female. A, habitus (dorsal view); B, habitus (lateral view); C, antennule; D, antenna; E, left mandible; F, right mandible; G, maxillule; H, maxilla; I, maxilliped. Scale bars: A, B = 0.5 mm; C, D, I = 0.0 5 mm; E – H = 0.03 mm.

FIGURE 4. Collettea bamberi n. sp., adult female. A, cheliped (inner); B, chela (inner); C, pereopod- 1; D, pereopod- 2; E, pereopod- 3; F, pereopod 4. Scale bars = 0.1 mm.

FIGURE 5. Collettea bamberi n. sp., adult female. A, pereopod- 5; B, pereopod 6; C, uropod. Male. D, pleopods. Small adult female. E, pereopod- 4; F, pereopod- 5. Scale bars: A, B, D = 0.1 mm; C = 0.03 mm; E, F = 0.05 mm.