Otagia neozelanica (Chilton, 1897)

Hughes, Lauren & Lörz, Anne-Nina, 2013, Family placement of the enigmatic Otagia neozelanica (Chilton, 1897) Haustorioidea: Otagiidae fam. nov. (Amphipoda: Crustacea), Zootaxa 3636 (3), pp. 439-450 : 443-449

Otagia neozelanica (Chilton, 1897)

Platyischnopus neozelanicus Chilton, 1897: 1 −6, Pl. V.

Otagia neozelanica .―Barnard & Karaman, 1991: 136–137.

Type material. Neotype, female, 3.8 mm, dissected, 3 slides, SEM pin mount, NIWA 85992, South Taranaki Bight, south of Hawera, New Zealand (-39.78, 174.29), soft sediment, 27 m, 1/11/2011, coll. NIWA (IKA1101/ 141).

Type locality. South Taranaki Bight, south of Hawera, New Zealand (-39.78, 174.298).

Additional material examined. New Zealand, South Taranaki Bight, south of Hawera, soft sediment coll. NIWA: Female specimen, 3.74 mm, whole animal SEM pin mount, NIWA 86537 (-39.78, 174.29), 27 m, 1/11/ 2011, (IKA1101/141); female specimen, 3.76 mm, partially dissected, carcass SEM pin mount and 3 slides, NIWA 86538 (-39.78, 174.29), 27 m, 1/11/2011, (IKA1101/141); 3 specimens, NIWA 79498 (-39.78, 174.29), 27 m, 1/11/ 2011, (IKA1101/141); 1 specimen, NIWA 79480 (-39.82, 174.23), 29 m, 23/09/2011, (IKA1101/23); 3 specimens, NIWA 79485 (-39.74, 174.25), 23 m, 1/10/2011, (IKA1101/77); 1 specimen, NIWA 79486 (-39.74, 174.25), 23 m, 1/10/2011, (IKA1101/79); 2 specimens, NIWA 79487 (-39.77, 174.23), 26 m, 1/10/2011, (IKA1101/80); 1 specimen, NIWA 79488 (-39.77, 174.23), 26 m, 1/10/2011, (IKA1101/80); 1 specimen, NIWA 79489 (-39.77, 174.23), 26 m, 1/10/2011, (IKA1101/81); 1 specimen, NIWA 79490 (-39.77, 174.23), 26 m, 1/10/2011, (IKA1101/ 81); 1 specimen, NIWA 79494 (-39.74, 174.13), 26 m, 31/10/2011, (IKA1101/101); 2 specimens, NIWA 79495 (- 39.74, 174.13), 26 m, 31/10/2011, (IKA1101/102); 1 specimen, NIWA 79496 (-39.78, 174.29), 27 m, 1/11/2011, (IKA1101/139); 2 specimens, NIWA 79497 (-39.78, 174.29), 27 m, 1/11/2011, (IKA1101/139); 1 specimen, NIWA 79499 (-39.75, 174.34), 21.5 m, 2/12/2011, (IKA1101/157); 2 specimens, NIWA 79500 (-39.75, 174.34), 21.6 m, 2/12/2011, (IKA1101/158); 1 specimen, NIWA 79501 (-39.75, 174.36), 23.7 m, 2/12/2011, (IKA1101/159); 4 specimens, NIWA 79503 (-39.82, 174.24), 25.8 m, 23/09/2011, (IKA1101/19); 1 specimen, NIWA 79515 (-39.83, 174.21), 35 m, 23/09/2011, (IKA1101/26).

Description. Based on neotype female 3.8 mm, NIWA 85992. Head longer than deep; rostrum cone-shaped with anteroventral keel and apical constriction; apical constriction with micro sensory pits; lateral cephalic lobe absent; anteroventral margin oblique; anteroventral corner absent; eye cluster round to ovoid, not ommatidial. Antenna 1 shorter than peduncle of antenna 2; peduncle with many plumose setae; peduncular article 1 shorter than article 2; article 2 longer than article 3; article 3 shorter than article 1; primary flagellum short, length less than peduncle, with 6 articles; accessory flagellum long, 4-articulate; callynophore and calceoli absent. Antenna 2 a fifth of body length; peduncle lined with plumose setae, article 4 length 2.5 times breadth, subequal to article 5; flagellum shorter than peduncle, 6-articulate. Upper lip entire. Mandible incisor with long smooth cutting edge; lacinia mobilis asymmetrical, broader than long with serrate margin; accessory setal row absent; molar columnar, large, covering two fifths of mandible surface, strongly triturating; mandibular palp article 1 short, as broad as long; article 2 long, medially flexed, 6 times as long as broad, 1.8 times article 3, with 3 short medial setae; article 3 longer than article 1, 3.4 times as long as broad, with apical cluster of long setae. Maxilla 1 inner plate with two apical plumose setae; outer plate with 9 apical setal teeth; palp 2-articulate, broad with many slender apical setae. Maxilla 2 inner plate subequal to outer plate, slightly longer than broad. Lower lip inner lobes present; mandibular lobes well-developed. Maxilliped basal endite with 3 short apical robust setae; ischial endite (obscured in slide mount), 3+ apical robust setae; palp article 2 medial surface with dense brush of slender setae; dactylus welldeveloped.

Coxae 1–4 progressively larger, longer than broad, overlapping. Gnathopod 1 dissimilar in form to gnathopod 2; simple; coxa subrectangular, 1.5 times as long as broad, smaller than coxa 2, not produced anteroventrally; basis elongate, 5 times as long as broad, anterodistal margin with short slender setae, posterodistal margin with very long slender setae; ischium and merus compressed, as broad as long; carpus 3.5 times as long as broad, longer than propodus, posterior margin with thick fringe of slender setae; propodus twice as long as broad, posterior margin with mainly distal slender setae; dactylus short, 3 times as long as broad, half the length of propodus. Gnathopod 2 minutely chelate; coxa subquadrate, twice as broad as long; basis elongate, 6 times as long as broad, posterodistal margin with long slender setae; ischium and merus compressed, as broad as long, posterior margin with a few long slender setae; carpus 2.8 times as long as broad, twice as long as propodus, posterior margin lined with fringe of slender setae; propodus subovate, twice as long as broad, posterior margin with mainly distal slender setae, posterodistal chelation acute; dactylus minute, with 3 apical teeth. Pereopods 3−4 dissimilar. Pereopod 3 coxa 1.4 times as long as broad; basis rectolinear, 4 times as long as broad; ischium compressed, slightly broader than long; merus rectolinear, 3 times as long as broad, much longer than propodus, anterior margin lined with 3 long plumose setae, posterior margin lined with 4 long plumose setae; carpus as broad as long, shorter than propodus, posterior margin with proximal long slender setae and distal long robust setae; propodus twice as long as broad, posterodistal corner with many long robust setae; dactylus vestigial, obscured by propodus robust setae. Pereopod 4 coxa as broad as long, larger than coxa 3, with well-developed posteroventral lobe, lobe posterior margin subquadrate; basis rectolinear 4.5 times as long as broad, anterodistal corner with single seta; ischium compressed, broader than long; merus 3 times as long as broad, much longer than propodus, anterior margin lined with 3 long plumose setae, posterior margin lined with 4 long plumose setae; carpus as long as broad, subequal to propodus, posterior margin lined with extremely long plumose setae; propodus 2.5 times as long as broad, posterodistal corner with cluster of long apical robust setae; dactylus vestigial. Pereopods 5–7 heterogeneous, pereopod 7 much shorter than and dissimilar to pereopods 5−6. Pereopod 5 coxa bilobate with broader posterior lobe, posterior lobe margin with 3 long robust setae; basis expanded, subovate, anterior margin with a few rows of long robust setae; ischium compressed, broader than long; merus expanded, posterior margin lined with plumose and robust setae; carpus expanded, twice as long as broad, longer than propodus, margins lined with long robust setae; propodus 3 times as long as broad, margins lined with long slender and robust setae; dactylus simple, tapering distally, 0.7 as long as propodus. Pereopod 6 subequal in length to pereopod 5; coxa bilobate with broader posterior lobe, posterior lobe margin with 2 long robust setae; basis expanded, subovate, anterior margin with long robust setae, facial surface with single medial plumose seta; ischium compressed, broader than long; merus expanded, posterior margin with plumose and robust setae, posterodistal corner with 2 plumose setae; carpus 3 times as long as broad, longer than propodus, margins with long robust setae; propodus 3 times as long as broad, margins with long slender and robust setae; dactylus simple, tapering distally, 0.7 times as long as propodus. Pereopod 7 two thirds the length of pereopod 5; basis strongly expanded, breadth 1.5 times length, subovate, posterior margin convex, posterior ventral lobe broadly rounded, inner surface with single medial plumose seta; ischium compressed, broader than long; merus expanded, posterior margin lined with long plumose setae; carpus broader than long, subequal in length to propodus, facial surface lined with rows of robust setae; propodus length subequal to carpus, twice as long as broad, with facial rows of robust setae; dactylus simple, tapering distally, medium length, 0.7 times length of propodus.

Pleon not compressed or dorsoventrally flattened. Pleonite 3 greatly extended, length subequal to pleonites 1−2 combined. Epimeron 1 subquadrate, anterior margin convex, corner with notch and small acute tooth. Epimeron 2 subquadrate, anterior margin convex, corner with notch and small acute tooth, ventral margin lined with plumose setae. Epimeron 3 subquadrate, anterior margin straight, scalloped, with slender setae, corner rounded, ventral margin with plumose setae. Pleopods 1–3 without coupling hooks. Pleopods 1–2 similar, peduncle twice as long as broad; basal article of outer ramus twice as long as broad, posterior margin with long slender setae, rami subequal in length. Pleopod 3 reduced, smaller than pleopod 1, peduncle twice as long as broad; inner ramus slightly shorter than outer ramus.

Uropod 1 biramous; peduncle 4 times as long as broad, 0.8 times length of outer ramus, with basofacial robust seta, dorsodistal corners each with large robust seta; outer ramus subequal in length to inner ramus, with marginal and apical long robust setae. Uropod 2 biramous, peduncle 3 times as long as broad, 1.2 times length of outer ramus, dorsodistal medial corner with broad robust setae, dorsal margins lined with long and short robust setae; inner ramus longer than outer ramus, with marginal and apical long robust setae. Uropod 3 biramous; peduncle twice as long as broad, 0.6 times length of outer ramus; rami foliaceous; outer ramus 2-articulate, 3 times as long as broad, article 2 long; inner ramus shorter than outer ramus, apices with cluster of long plumose setae. Telson laminar; longer than broad; cleft to 66% of length, lobes divergent; 2 pairs of lateral small plumose seta, lobe apices each with pair of robust setae (1 large and 1 medium length).

Habitat. Soft sediment, 0– 35 m.

Distribution. New Zealand: Otago and South Taranaki Bight.