Parafilitanais denticulus, Larsen, Kim, 2013

Larsen, Kim, 2013, The ANDEEP Tanaidacea (Crustacea: Peracarida) revisited II: the family Anarthruridae and family incertae sedis, with descriptions of three new species and the erection of a new genus, Zootaxa 3694 (4), pp. 367-380 : 372-375

Parafilitanais denticulus n. sp.

( Figs. 3 & 4 )

Material examined. Holotype: non-ovigerous female (Reg. # ZMH K-43956), ANDEEP- SYSTCO, DZMB-HH 1338, station 17, 70 °04.83’S, 03°21.50’W, 2051.4 m, 14 March 2002, EBS-epi. Paratypes (Reg. # ZMH K-43957) one non-ovigerous female (dissected), same data as holotype. One non-ovigerous female ANDEEP- SYSTCO, DZMB-HH 1424, same locality. One non-ovigerous female ANDEEP- SYSTCO, DZMB-HH 1602, same locality.

Diagnosis. Antennule article 1 longer than rest of antennule combined; article 4 l/w ratio 2. Maxilliped palp article 2 with blunt denticle-shaped outer setae. All pereopods with meral and carpal bayonet setae. Pereopods 1 to 3 merus and carpus with bayonet setae; propodus with distal spines. Uropodal endopod article 2 shorter than half of article 1.

Etymology. Named after the diagnostic blunt denticle-shaped outer setae on the maxilliped article 2.

Description. Body from holotype (1.8 mm), appendages from adult female paratype.

Body ( Fig. 3 A, B). Elongated, nine times as long as broad. Cephalothorax shorter than combined length of pereonite I and 2. Eyelobes absent. Pereonites l and 2 wider than long. Pereonites 4 and 5 longer than wide. Pereonite 6 as wide as long. All pleonites subequal, slightly narrower than pereon and one third as long. Pleotelson longer than two pleonites combined, apex blunt, with two pairs of small setae.

Antennule ( Fig. 3 C). Shorter than cephalothorax. Article 1 longer than rest of antennule, with one simple and setulated distal setae. Article 2 about one third as long as article 1, with one simple and one setulated distal setae. Article 3 square, with two simple distal setae. Article 4 longer and thinner than article 3, with five distal setae and one aesthetasc.

Antenna ( Fig. 3 D). More than half as long as antennule. Article 1 broken but fused to cephalothorax. Article 2 longer but wider than article 3, naked (possibly an artefact as we would expect a dorsal seta here). Article 3 square, naked. Article 4 longer than other articles, with three distal setae. Article 5 as long as article 2, with one simple distal seta. Article 6 minute with two long and one short distal setae.

Mouthparts. Labrum ( Fig. 3 E) hood-shaped, setulose. Mandibular molar process pointed and longer than incisor. Left mandible ( Fig. 3 F) lacinia mobilis reduced to a short process which appears at least partly fused with mandibular body (possibly a result of mandible orientation); incisor with two blunt denticles. Right mandible ( Fig. 3 G) incisor narrow and only minutely bifurcate (hardly visible). Labium ( Fig. 3 H) lobes naked, with small lateral expansion. Maxillule ( Fig. 3 I) endite with eight distal spiniform setae. Palp with two long apical setae. Maxilla not recovered. Maxilliped ( Fig. 3 J) endite with outer and inner unarticulated processes. Basis fused and naked. Palp article 1 naked. Article 2 with two setae on inner margin and blunt spiniform outer seta. Article 3 with three inner setae. Article 4 with three distal and one small outer setae. Epignath ( Fig. 3 K) with blunt apex.

Cheliped ( Fig. 4 A). Basis divided unequally by elongated sclerite, as long as carpus, with one dorsodistal seta. Merus triangular with one ventral seta. Carpus marginally shorter than propodus including the fixed finger, with ventral process bearing two setae, dorsodistally with small seta. Propodus naked. Fixed finger with three inner and two ventral setae, with sharp inner distal process. Dactylus marginally longer than fixed finger.

Pereopod 1 ( Fig. 4 B). Coxa with one seta. Basis as long as three succeeding article combined, naked. Ischium with one small ventral seta. Merus longer than carpus, widening distally and with one ventrodistal bayonet seta. Carpus two thirds as long as propodus, with one dorsodistal bayonet seta. Propodus longer than half of basis, with two ventrodistal spiniform setae and several distal spines. Dactylus and unguis combined shorter than propodus. Dactylus with small ventrodistal spine. Unguis with bifid apex.

Pereopod 2 ( Fig. 4 C) and 3 (Fig. D). As pereopod 1 except: coxa naked. Carpus with both dorso- and ventrodistal bayonet setae.

Pereopod 4. ( Fig. 4 E). Coxa with one seta. Basis as long as three succeeding article combined, naked. Ischium with one small ventral seta. Merus shorter than carpus, widening distally and with two ventrodistal bayonet setae. Carpus two thirds as long as propodus, with two distal bayonet setae and bone-shaped seta. Propodus shorter than half of basis, with three distal spiniform setae. Dactylus and unguis combined longer than propodus. Dactylus with small ventrodistal spine.

Pereopod 5 ( Fig. 4 F). As pereopod 4 except: propodus broken.

Pereopod 6. Not recovered.

Pleopods. Not present in female.

Uropods. ( Fig. 3 L). Basal article more than half the length of endopod article 1, naked. Endopod article 1 more than twice as long as article 2, with one setulose distal setae; article 2 with five simple distal setae. Exopod completely reduced.

Remarks. The blunt denticle-shaped outer seta on the maxilliped palp article 2 is unique to this species. It can furthermore be separated from P. vadosus BłaŻewicz-Paszkowycz & Bamber, 2012 by the much longer antennule article 1 and much shorter article 4, the almost twice as long cheliped carpus, and the presence of bayonet setae on the merus and carpus of pereopods 2 and 3. From P. caudatus Kudinova-Pasternak, 1989 , P. similis Kudinova- Pasternak, 1990 and P. mexicanus Larsen, 2002 the new species can also be distinguished by the uropodal endopod article 2 being shorter than half of article 1.

Figures

FIGURE 3. Parafilitanais denticulus n. sp. A, paratype, dorsal view; B, holotype, lateral view, scale bar 0.5 mm; C, antennule; D, antenna; E, labrum, dorsal view; F, left mandible; G, right mandible; H, labium; I, maxillule; J, maxilliped; K, epignath; L, uropod. Scale bars 0.1 mm.

FIGURE 4. Parafilitanais denticulus n. sp., paratype, A, cheliped; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; Scale bar 0.1 mm.