Robustochelia robusta ( Kudinova-Pasternak, 1970 )

Wiak, Piotr Jó Ż & Błażewicz-Paszkowycz, Magdalena, 2007, New records of two rare genera, Monstrotanais Kudinova-Pasternak, 1981 and Robustochelia Kudinova-Pasternak, 1983 (Tanaidacea: Crustacea), Zootaxa 1505, pp. 19-35 : 27-31

Robustochelia robusta ( Kudinova-Pasternak, 1970)

( Figs 4–6 )

Diagnosis: Pereonites 2–6 wider than long. Pleon longer than combined length of pereonites 5 and 6. Pereopods 1–3 propodus setae shorter than dactylus. Pereopods 4–6 propodus elongated (over four times as long as wide).

Material examined: Holotype female, Mc957, Vitjaz Sta 5622, 45º17'N, 155º23'E, depth 4945 m, coll. in 1966.

Amended description: Female ( Fig. 4A ). Body 6.6 times as long as wide, carapace twice as long as pereonite-1, much narrower than pereonites, 0.75 times as wide as pereonite-1; pereonite-1 shortest, 0.7 times as long as pereonite-2, with two short, simple seta dorso-laterally; pereonites 2, 3, 4 and 5 subequal, pereonite-2 0.75 times as long as wide; pereonite-6 little as long as pereonite-1; pleon as long as pereonites 2, 3 and half of pereonite-4 combined; pleotelson about as long as pereonite-6; each pleonite with one short simple seta laterally.

Antennule ( Fig. 5 A): 5-articled, 0.7 times as long as carapace; article-1 more than twice as long as wide, about three times as long as article-3, with one simple and six bipinnate setae subdistally; article-2 1.3, as long as article-3, with two simple (one long and one short) and four bipinnate setae distally; article-3 short, half as long as article-4, with one long, simple seta; article-4 narrow, 0.7 times as long as article-1; article-5 vestigial tipped by one aestethasc and six simple setae.

Antenna ( Fig. 5 B): Article-1 broken; article-2 little as long as article-3, with one simple, subdistal seta; article-3 as long as wide, with one subdistal, simple seta; article-4 more than twice as long as article-3, with four short setae distally; article-5 as long as article-2, with one long seta distally; article-6 shortest, with six (five long and one short) terminal, simple setae.

Mouth parts: Labrum ( Fig. 5 C) hood-shaped, covered by numerous minute setae. Mandibles ( Figs 5 D, E) massive; molar process poorly developed, pointed, bent downward; lacinia mobilis well developed. Maxillule ( Fig. 5 G) with nine spiniform setae and numerous minute setae terminally. Palp lost during dissection. Maxilla lost during dissection. Maxilliped ( Fig. 5 H) bases only proximally fused, 0.7 times as long as wide, with one short seta distally; endite with two setae distally; palp 4-articled: article-1 naked; article-2 with one short seta on outer margin and three setae on inner margin (one long); article-3 with four simple setae (three long and one short) on inner margin; article-4 slender, with five inner, setulated setae and small outer seta.

Cheliped ( Fig. 5 I): Basis 1.3 times as long as wide; merus triangular, naked; carpus massive, 1.4 times as long as wide, with two setae on ventral margin and one seta on dorsal margin; propodus as wide as long, with three setae on inner margin, strongly calcified ventral carina and two simple setae on ventral margin and with three setae on inner margin near dactylus insertion; fixed finger short, triangular, strongly calcified; dactylus about half as long as propodus; unguis 0.5 times as long as dactylus.

Pereopod-1 ( Fig. 6 A): Of walking type; basis as long as ischium, merus and carpus combined, more than four times as long as wide; ischium with short seta; merus as long as carpus, with two short setae distally; carpus with four short setae subdistally; propodus 1.4 times as long as carpus, with four setae subdistally; dactylus half as long as carpus; unguis as long as dactylus, dactylus and unguis combined about as long as propodus.

Pereopod-2 ( Fig. 6 B): Similar to pereopod-1, but propodus with three relatively long, subdistal setae; coxa with one simple seta.

Pereopod-3 ( Fig. 6 C): Similar to pereopod-2.

Pereopod-4 ( Fig. 6 D): Of walking type; coxa with simple seta; basis subequal to carpus and propodus combined, more than three times as long as wide, with one bipinnate seta on ventral margin; ischium with two setae; merus with two short, spiniform setae ventrally; carpus 0.45 times as long as basis, with four short, spiniform setae distally; propodus 0.6 times as long as basis, with one bipinnate seta in middle dorsally, two subdistal simple setae and one distal simple seta; dactylus half as long as propodus, with two minute setae distally; unguis as long as dactylus, unguis and dactylus combined as long as propodus.

Pleopod ( Fig. 6 G): Basal article naked. exopod with eleven setae distally and one seta proximally separated by large gap from the others, and one subdistal setae on inner margin; endopod with eighteen setae on outer margin, no gap between most proximal seta and others.

Uropod ( Fig. 6 H): Endopod 2-articled; article-1 as long as article-2; article-2 with one seta in middle and four long, terminal setae; exopod 1-articled, about as long as proximal article of endopod, with one seta in middle and two long setae terminally.

Distribution: Species known only from type locality: Kurile Trench 45º17'N, 155º23'E at the depth 4945 m.

Figures

FIGURE 5. Robustochelia robusta. Holotype female. A) Antennule; B) Antenna; C) Labrum; D) Left mandible; E) Right mandible; F) Labium; G) Maxillule; H) Maxilliped; I) Cheliped. Scale bars equal 0.1 mm.

FIGURE 6. Robustochelia robusta. Holotype female. A) Pereopod- 1; B) Pereopod- 2; C) Pereopod- 3; D) Pereopod- 4; E) Pereopod- 5; F) Pereopod- 6; G) Pleopod; H) Uropod. Scale bars equal 0.1 mm.

FIGURE 4. A) Robustochelia robusta. Holotype, female. (A) Body, lateral; (B) Robustochelia angusticephala. Pereopod- 4. Scale bars equal 0.1 mm.