Anarthrurella clairae, Bird, Graham, 2004

Bird, Graham, 2004, Tanaidacea (Crustacea) of the Northeast Atlantic: non­filiform species of Anarthruridae Lang from the Atlantic Margin, Zootaxa 471, pp. 1-44 : 30-33

Anarthrurella clairae sp.nov. (Figs. 13–14)

Anarthrura simplex: Holdich & Bird, 1986: 79 , 98, table 2.

Material examined. Holotype: neuter, BT244, ( NMSZ:2004.012). Paratypes: three neuters (BT244).

Description. Neuter/non­ovigerous female. Tiny anarthrurid, body (Fig. 13A) slender, 8.9 times longer than broad, length 1.09–1.47 mm. Cephalothorax 1.24 times longer than broad, 14% of body length, rostrum small. Pereonite­1 narrower caudally, pereonites 2–6 subrectangular with rounded corners, each with two dorsolateral setae, 0.55, 0.83, 0.88, 1.05, 1.08, and 0.92 times longer than broad respectively. Pleon 2.1 times longer than broad, 21% of body length, pleonites 1 and 5 longer than 2–4; pleonite­5 with two dorsolateral setae. Pleotelson (Figs. 13B–C) conical, 0.73 times as long as broad, with two distal setae and two sensory setae near apex, apex slightly deflexed with two terminal setae.

Figure 13. Anarthrurella clairae . Non­ovigerous female A, dorsal view; B–C, pleonite 5 and pleotelson lateral and dorsal view; D, antennule; E, antenna; F, labrum, ventral view; G, maxillule endite, distal; H, maxilliped; J, cheliped; K, anterior seta of cheliped propodus; L, variation in fixed finger dentition. Scale bar 0.5 mm (A) 0.21 mm (B–C), 0.14 mm (D–E,H–L), 0.1 mm (F–G).

Antennule (Fig. 13D) three­quarters length of cephalothorax; article­1 twice as long as broad, article­2 just longer than broad; article­4 as long as article­2; setation as figured. Antenna (Fig. 13E) typical of family, 80% length of antennule; article­6 with one short and one long thickened (fused?) seta.

Labrum (Fig. 13F) conical, relatively large. Maxillule endite (Fig. 13G) with at least three spiniform setae. Maxilliped (Fig. 13H) basis small in relation to palps, without setae; endites simple, rectangular; palp article­3 with three strongly plumose setae article­4 with five large plumose setae.

Cheliped (Fig. 13J) with numerous microtrichia; pseudocoxa long and ovoid; basis short and cylindrical, with lateral seta; merus with strong ventral seta; carpus 1.7 times longer than greatest width, with two dorsal and two ventral setae; propodus with large lateral fold, clearly visible in dorsal view, with anterior spiniform seta (Fig. 13K); fixed finger thick (almost cylindrical in cross­section), with one ventral seta, one seta at articulation with dactylus, and three near incisive margin; incisive margin (Fig. 13L) shallow­convex, with three or four hook­like teeth; dactylus typical of family, with strong anterior spiniform seta.

Pereopod­1 ( Fig. 14 A) basis curved, four times longer than broad; ischium with seta; merus about twice as long as broad, without setae (?); carpus subrectangular, 1.7 times longer than broad and just shorter than merus, with two distal setae; propodus 2.5 times longer than broad, with ventrodistal seta; dactylus and unguis together just shorter than propodus, dactylus with accessory seta. Pereopods 2–3 ( Figs. 14 B–C) similar, but basis slightly shorter and merus only half as long as in pereopod­1, with two ventral setae; carpus just longer than broad; propodus shorter than in pereopod­1.

Pereopods 4–6 ( Figs. 14 D–F) similar, basis tumid, 2.75 times longer than broad, pereopod­6 at least with a sensory seta; ischium without seta; merus short, as long as broad, with two ventral spiniform setae; carpus just longer than merus, with three spiniform seta and a small dorsal seta; propodus as long as carpus, with terminal spine and three distal spiniform setae, one longer than the other two; dactylus and unguis together about as long as propodus.

Pleopods (not figured) small, with distal setae.

Uropod ( Fig. 14 G) exopod short, as long as broad, with three distal setae; endopod 2­ articled, twice as long as basal article, article­1 about two­thirds total length, with seta near articulation, article­2 with four terminal setae.

Type locality. Sound of Kerrera (Firth of Lorn), Argyll, Scotland, 56o 22.2’N 5o 32.3’W, 30 m, shelly mud.

Etymology. For my wife Claire.

Remarks. The smallest of the anarthrurids in this paper (including known mancae), misidentified by me as preparatory males of A. simplex . Its small size and slender build could lead it to being overlooked or inefficiently collected with sieve mesh­sizes of = 0.5 mm. This is the second new species from the Oban area along with Subulella scotti Holdich & Bird, 1986 .

Figures

FIGURE 14. Anarthrurella clairae. Non­ovigerous female A – F, pereopods 1 – 6 respectively; G, uropod. Scale bar 0.14 mm (A – G).