Araphura arvedlundi Larsen & Araújo-Silva, 2009

Larsen, Kim, Araújo-Silva, Catarina De L. & Coelho, Petrônio Alves, 2009, Tanaidacea from Brazil. I. The family Tanaellidae Larsen & Wilson, 2002, Zootaxa 2141, pp. 1-19 : 5-9

Araphura arvedlundi Larsen & Araújo-Silva n. sp.

( Figs 1–3 )

Material examined. Holotype. male (DOUFPE -14.035), 3.2 mm, 3Loc-Bia4 Station 12 R2 (2–5). Allotype, non-ovigerous female (DOUFPE -14.044), 3Loc-Bia4 Station 9 R3 (2–5). Paratype. 1 non-ovigerous female (DOUFPE -14.046), 2.5 mm, 3Loc-Bia4 Station 12 R2 (5–10) (dissected). Station data given in table 2.

Diagnosis. Female. Body elongate. Carapace shorter than pereonite 1 and 2 combined. Pereonite 2–5 elongate and pereonite 6 square. Pleotelson longer than combined length of three pleonites. Pleotelson apex without conical process. Uropodal exopod process less than half as long as first endopod article. Male. Pleonites with pleopods. Pleotelson no longer than 3 last pleonites combined. Antennule thinner than female, article 2 and 4 longer than that of female.

Etymology. Named after the behavioral ecologist Michael Arvedlund in recognition to his contributions to coral reef research.

Description. male holotyp e, 3.2 mm (not dissected)

Body ( Fig. 1 A, B). About 11 times longer than wide. Cephalothorax shorter than 2 combine pereonites. Pereonites. Pereonite 1 and pereonite 6 as wide as long. Pereonite 2, 3, 4, and 5 as long as wide. Pleon longer than 25 % of body length. Pleonites subequal, with pleopods and very weak ventral keel. Pleotelson not longer than 3 last pleonites combined.

Antennule ( Fig. 1 C). Shorter than carapace. Article 1 not longer than rest of antennule, with one simple distal seta. Article 2 half lenght of article 1, with 1 small setulated and one simple distal seta. Article 3 less than half the lenght of article 2, with 1 small setulated and one simple distal setae. Article 4 about as long as article 2 but thinner and tapering, with 1 aestetasc, 3 simple long and one simple short distal setae.

Uropod ( Fig. 1 D). Basal article (including exopod process) slightly shorter than endopod. Exopod process with one small and one long simple setae, as long as half of first endopod pseudoarticle. Endopod uniarticulate but with pseudoarticulation with one long simple subdistal seta and three long and one small setulated distal setae.

Female paratype, 2.5 mm (dissected)

Body ( Fig. 2 A, B). As males except: pleonites without pleopods or ventral keel. Pleotelson longer than 3 last pleonites combined.

Antennule ( Fig. 2 C). Much shorter than carapace. Article 1 as long as rest of antennule, with one small setulated and one simple distal setae. Article 2 less than half the lenght of article 1, with 2 small setulated and one simple distal setae. Article 3 less than half lenght of article 2, with one simple distal seta. Article 4 about as long as article 2 but thinner and tapering, with 1 aestetasc, 4 simple, one small setulate distal setae.

Antenna ( Fig. 2 D). About 15 % shorter than antennule, with 6 articles. Article 1 fused to peduncle on cephalothorax, naked. Article 2 longer than article 3, with one robust dorso-distal seta. Article 3 with one robust dorso-distal seta. Article 4 longer than other articles but subdivided by clear fusion line midlength, with one small setulated seta medially and one small setulated and 2 simple distal setae. Article 5 longer than article 1, with 2 long simple distal setae. Article 6 minute, with one small and three long simple setae.

Mouthparts. Labrum ( Fig. 2 E) prominent, clearly demarcated from clypeus, with sparse distal setulation. Mandibles ( Fig. 2 F, G) molar thin and tapering, bent donward, ending in prominent spine cluster. Left mandible ( Fig. 2 F) incisor with clear medial spine. Lacinia mobilis in form of single spine. Right mandible ( Fig. 2 G) incisor bifurcate and with both dorsal and distal processes. Labium ( Fig. 2 H) with small inner distal setules. Maxillule ( Fig. 2 I) with eight distal spiniform setae of which at least three are setose, endite with two dorsal setules, palp with two distal setae. Maxilla ( Fig. 2 J) elongated and featureless. Maxilliped ( Fig. 2 K) basis with one long seta at palp attachment; endites as wide as basis with lateral spine and short seta and inner process palp article 1 naked, article 2 with three inner and one outer setae, article 3 with three outer setae, article 4 with four outer and one inner setae. Epignath ( Fig. 2 L) short and tapering into a blunt point, without terminal seta.

Cheliped ( Fig. 3 A). Basis unequally divided by sclerite, shorter than carpus, proximal part narrow, distal part wide. Merus prominent, more than half as long as carpus, with one ventral seta. Carpus as long as propodus including fixed finger, with ventral process and two ventral setae. Propodus stout, with three small setae on inner margin and one near propodus insertion. Fixed finger with two ventral setae, inner prominent processes and three inner setae. Dactylus smooth and naked.

Pereopod 1 ( Fig. 3 B). Coxa with one simple seta. Basis naked. Ischium with one ventral seta. Merus widening distally, with one ventral seta. Carpus rectangular, as long as merus, with two spiniform distal setae. Propodus longer than carpus, half as long as basis, with one subdistal ventral spiniform seta and dorsal spine. Dactylus and unguis combined shorter than propodus.

Pereopod 2 ( Fig. 3 C). As pereopod 1 except; basis with dorso-medial setulated seta. Carpus with two serrated spiniform and one simple distal setae.

Pereopod 3 ( Fig. 3 D). As pereopod 2 except carpus with three serrated spiniform setae.

Pereopod 4 ( Fig. 3 E). Longer than pereopod 1–3. Basis with dorso-medial setulated seta. Ischium with two ventral setae. Merus with two distal serrated spiniform setae. Carpus longer than merus, with four serrated spiniform and one bone-shaped distal setae. Propodus narrower but longer than carpus, with one spiniform dorsodistal, two serrated spiniform ventro-distal setae and dorsal spinules. Dactylus and unguis not fused, shorter than propodus.

Pereopod 5 ( Fig. 3 F). As pereopod 4 except; basis with two ventral setulose setae. Propodus wider and shorter than on pereopod 4, with ventral indentations.

Pereopod 6 ( Fig. 3 G). As pereopod 4 except. Basis naked. Ischium with apparently only one seta (suspicion of loss during handling). Propodus with one dorsodistal spiniform and three distal serrated spiniform setae.

Pleopods missing in female.

Uropod ( Fig. 2 M). Basal article (including exopod process) as long as endopod. Exopod process with one small and one long simple setae, as long as half of first endopod pseudoarticle. Endopod uniarticulate but with pseudoarticulation, with one small setulated and one long simple subdistal setae and three long and one small setulated distal setae.

Remarks. This species is morphologically close to the Pacific species A. rectifrons (Kudinova-Pasternak, 1973) , but that species has a longer and narrower antenna article 3 and has longer uropods.

Figures

FIGURE 1. Araphura arvedlundi n. sp., male holotype. A, dorsal view, scale bar = 1 mm; B, lateral view; C, antennule; D, uropod. Scale bars = 0.2 mm.

FIGURE 2. Araphura arvedlundi n. sp., female allotype (A + B) and paratype (C – M). A, dorsal view, scale bar = 1 mm; B, lateral view; C, antennule; D, antenna; E, labrum; F, left mandible; G, right mandible; H, labium; I maxillule; J, maxilla; K, maxilliped; L, epignath; M, uropod. Scale bars = 0.2 mm.

FIGURE 3. Araphura arvedlundi n. sp., female paratype. A, cheliped; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; G, pereopod 6. Scale bars = 0.2 mm.