Paragathotanais triungiusus, Larsen, Kim, Bird, Graham & Ota, Mayumi, 2013

Larsen, Kim, Bird, Graham & Ota, Mayumi, 2013, The ANDEEP Tanaidacea (Crustacea: Peracarida) revisited I: the family Agathotanaidae Lang, with description of four new species, Zootaxa 3630 (3), pp. 424-444 : 435-438

Paragathotanais triungiusus n. sp. Larsen & Bird

Figs 7–8

Material examined. Holotype: non-ovigerous female, (Reg. # ZMH K-43316), ANDEEP II, sample # DZMB-HH 10394, station 141, 58°25.08'S, 25°00.77'W, 2313 m, 23 March 2002, EBS-epi. Paratypes (Reg. # ZMH K-43317): one non-ovigerous female, same locality, date and gear as holotype, dissected. One non-ovigerous female, ANDEEP II, sample # DZMB-HH 10393, station 140, 58°15.98'S, 24°53.73'W, 2947 m, 22 March 2002, EBS-epi. (Reg # to be added after acceptance). Damaged individuals found from ANDEEP II, sample # DZMB-HH 10391, station 136, 64°01.54'S, 39°06.88'W, 4747 m, 11 March 2002, EBS-epi. and ANDEEP II, sample # DZMB-HH 10392, station 139, 58°14.10'S, 24°21.22'W, 3941 m, same locality and date, EBS-epi, probably also belong to this species.

Diagnosis, female. Pereopods 1–6 propodus without numerous distal spines. Pereopods 4–6 dactylus with two long accessory spiniform setae at unguis insertion (or possibly part of the unguis itself). Uropod short (less than half as long as pleotelson), not fused with basal article. Small exopodal process present, with seta.

Etymology. Name derived from the Greek, alluding to the ‘triple’ unguis on pereopods 4–6.

Description. Female, body from holotype, appendages from dissected paratype.

Body ( Fig. 7 A). Heavily calcified, about ten times as long as wide. Cephalothorax with clear lateral shield, naked, longer than wide, shorter than pereonites 1 and 2 combined. Pereonites lateral shoulders defined. Pereonite- 1 marginally wider than long, pereonites 2–5 longer than wide, pereonite-6 as wide as long. Pleon including pleotelson 0.15 times as long as total body length. All pleonites subequal and unfused. Pleotelson just shorter than last four pleonites combined, acorn-shaped, apex rounded, with paired setae, and covered by dorsal plate.

Antennule ( Fig. 7 B). More than half as long as carapace. Article-1 marginally longer than rest of antennule combined, with one simple subdistal seta. Article-2 shorter than half of article-1, with one long and two short simple distal setae. Article-3 as long as half of article-2, with two distal simple setae. Article-4 with one long simple distal seta. Terminal cap-like article minute and partly fused to article-4, with one tiny and two long simple setae and two aesthetascs.

Antenna ( Fig. 7 C). Longer than antennule article-1. With five apparent articles. Article-1 with single dorsodistal seta, longer than article-2. Article-2 with one dorsodistal seta, longer than article-4. Article-3 longer other articles combined, with one simple distal seta. Article-4 less than half as long as article-2, tapering, with one simple distal seta. Article-5 minute, with one tiny and three longer simple distal setae.

Mouthparts. Labrum ( Fig. 7 D) narrower than clypeus, distal edge setulose. Mandibles ( Fig. 7 E,F) with acuminate molars tipped with three slender spines. Right mandible ( Fig. 7 E) incisor narrower than on left mandible, weakly bifurcate. Left mandible ( Fig. 7 F) lacinia mobilis in the shape of a simple blunt spine, incisor blunt trifurcate and with subdistal denticle. Labium ( Fig. 7 G) tapering medially setulose process. Maxillule ( Fig. 7 H) endite with eight spiniform distal setae. Palp shorter than endite, with two terminal setae. Maxilla ( Fig. 7 I) of simple ovoid shape. Maxilliped ( Fig. 7 J) basis naked. Endites apparently without setae but with blunt distal process. Palp article-1 naked, article-2 with two simple setae on inner margin, article-3 with three simple setae on inner margin, article-4 only half as wide and long as article-3, with four simple inner setae. Epignath ( Fig. 7 K) narrow and ending in a thin but unarticulated spine.

Cheliped ( Fig. 7 L). Sclerite large (not illustrated), not protruding below ventrum of cephalothorax. Basis attached ventrally, naked, longer than merus. Merus with one medial seta. Carpus marginally longer than propodus including fixed finger, with two medioventral setae arising from a process and one dorsal seta. Propodus with one wide and blunt inner seta behind dactylus insertion. Fixed finger with one simple ventral and three setae on inner margin, inner margin with subdistal serration. Dactylus as long as fixed finger, with two short spiniform setae on inner margin.

Pereopod-1 ( Fig. 8 A) coxa with one seta. Basis shorter than the four succeeding articles combined, naked. Ischium with one seta. Merus shorter than carpus, widening distally, with two simple ventrodistal setae. Carpus shorter than propodus, rectangular, with two short spiniform distal setae. Propodus about 0.5 times as long as basis, with one simple dorsal and one short spiniform ventral setae. Dactylus and unguis combined shorter than propodus.

Pereopod-2 ( Fig. 8 B) as pereopod-1 except: merus with one short spiniform ventrodistal seta. Carpus with two short spiniform ventrodistal and one simple dorsodistal setae.

Pereopod-3 ( Fig. 8 C) as pereopod-2.

Pereopod-4 ( Fig. 8 D) coxa naked. Basis not wider than those of pereopods 1–3, naked. Ischium with only one seta. Merus with two bayonet setae, shorter than carpus. Carpus with three distal bayonet setae and one dorsodistal bone-shaped seta. Propodus with three long (longer than dactylus) distal bayonet setae. Dactylus and unguis combined longer than propodus. Dactylus/unguis with two long accessory spines at unguis insertion.

Pereopod-5 ( Fig. 8 E) as pereopod-4.

Pereopod - 6 ( Fig. 8 F) as pereopod-4 except propodus with four long (longer than dactylus) distal bayonet setae.

Uropod ( Fig. 7 M) basal article not fused with endopod. Exopod process small with one long (as long as pleotelson) seta. Endopod longer than basal article, with four distal/subdistal simple setae.

Remarks. As in the species discussed above in the remarks for Paragathotanais diunguisus , P. triunguisus n. sp. is equipped with long accessory spiniform setae at the unguis insertion on pereopods 4–6. It differs from most of these taxa by having two such spiniform setae and from P. vikingus Bird (which also has the two long accessory spiniform setae) by lacking the smaller dactylar and propodal spines on all pereopods, by lacking maxilliped endite setae, by lacking pereonal crenulation, and in having a more slender cheliped. It is not possible to distinguish P. triunguisus from the Gulf of Mexico species, as the latter is only partially described and from a male only. The Gulf of Mexico location however, makes it unlikely to be conspecific with P. triunguisus . The nearby-found P. i p y lacks the dactylus spiniform setae and can be separated without dissection.

Figures

FIGURE 7. Paragathotanais triunguisus n. sp., female A, holotype, lateral view, scale bar 1.0 mm. B – M, paratype, scale bars 0.5 mm. B, antennule. C, antenna. D, labrum, lateral view. E, right mandible. F, left mandible. G, labium, single lobe. H, maxillule. I, maxilla. J, maxilliped. K, epignath. L, cheliped. M, uropod.

FIGURE 8. Paragathotanais triunguisus n. sp., female, paratype, scale bar 0.5 mm. A, pereopod- 1. B, pereopod- 2. C, pereopod- 3. D, Pereopod- 4. E, pereopod- 5. F, pereopod- 6.