Parafoxiphalus longicarpus, Alonso de Pina, 2001

Pina, M. Alonso De, 2001, new phoxocephalids (Crustacea: Amphipoda: Phoxocephalidae) from the south-west Atlantic, Journal of Natural History 35 (4), pp. 515-537 : 517-526

Parafoxiphalus longicarpus n. sp.

(®gures 1±6)

Material examined

ALLOTYPE, ovig. m approx. 7.5 mm, Chubut: Golfo Nuevo, PenõÂnsula ValdeÂs, Punta Pardelas (42ss37¾S, 64ss16¾W), 2±5 m depth, 31 October 1995, MACN No. 34175.

HOLOTYPE, l ca 7 mm, same data, MACN No. 34176 . PARATYPES, same data, one ovig. m ca 6 mm, MACN No. 34177; two mm (with setose oostegites) ca 6 mm, MACN No. 34178; seven subadult mm 3.2±4.3 mm, MACN No. 34179. Collectors: Meijide and Ianovski, donor: D. Roccatagliata. BahõÂa Nueva, Gol ®to (approx. 42ss46¾S, 65ss02¾W), 8±10 m depth, 6 August 1992, one subadul t m ca 4.5 mm, MACN No. 34180. Collector and donor: G. Pagnoni .

Description

Allotype, ovigerous female (body length approximately 7.5 mm). Head about 17% of total body length, greatest width about 75% of length, rostrum unconstricted, broad, elongate, exceeding apex of article 2 on antenna 1. Eyes medium, subovate, intensely pigmented, brownish red in alcohol. Antenna 1, peduncle article 1 about 1.4 times as long as wide, about 1.8 times as wide as article 2, ventral margin with about seven plumose setules and three apicofacial setules, produced dorsal apex with two plumose setules and two setae of diOEerent length; article 2 about 0.6 times as long as article 1, with ventral spread crescent of 11 setae, ®ve shorter apical setae and one plumose setule, dorsal apex with one short seta; primary ¯agellum with 12 articles, about as long as peduncle, bearing one aesthetasc on each of articles 4±11; accessory ¯agellum with seven articles. Antenna 2, article 1 simple; article 3 with three apicofacial setules and one long seta; spine formula of article 4 5 4-5-3-2, dorsal margin with notch bearing ®ve setae, ventral margin with seven groups of three to four long to medium setae, one long ventrodistal spine set facially; article 5 about 0.7 times as long as article 4, facial spine formula 5 5, dorsal margin bearing two small apical setae, ventral margin with four sets of two long to short setae, four ventrodistal long to medium spines, one of these facial; ¯agellum about 1.1 times as long as peduncle articles 4 and 5 combined, with 13 articles.

Upper lip, epistome ¯at, not produced. Mandibles, right incisor with three de®ned teeth, left incisor with four teeth and weak hump between them; right lacinia mobilis with four teeth, left lacinia mobilis with ®ve teeth; right rakers about 13, three of these short, left rakers nine plus about two very small; molars composed of elongate plaques bearing six long spines closely disposed, with pubescence; palp article 1 short, article 2 with one short inner apical seta and two other short and long inner setae, article 3 about 1.35 times as long as article 2, oblique apex with 11 spinesetae, basofacial formula5 0-3. Lower lip, each outer lobe with one cone, mandibular processes broad. Maxilla 1, inner plate ordinary, bearing one apicofacial plumose seta, one similar apicomedial plumose seta and two much shorter apicolateral simple setae; outer plate with 11 spines, outer apical spine enlarged; palp article 2 with about eight apical spines. Maxilla 2, both setose plates extending subequally; outer plate slightly broader than inner, outer with one apicolateral seta; inner with three or four medial plumose setae. Maxilliped, inner plate with two large thick apical spines, three apicofacial setae and four medial setae, all plumose; outer plate with nine medial masticatory spines and ®ve lateral plumose setae; palp article 1 without apicolateral seta, article 2 with one apicolateral seta and medial margin moderately setose, article 3 with facial and lateral setae, article 4 slender carrying a long nail about 0.45 times as long as dactylus, with two accessory setules.

Coxae 1 and 2 weakly expanded anteriorly, anterior margin almost straight. Coxa 3 rectangular. Coxa 4, anterior and posterior margins divergent, posterior margin oblique, straight, posterodorsal corner rounded, posterodorsal margin concave, width±length ratio 5 1:1. Coxae 1±4, main ventral setae5 7-8-8-8, posteriormost seta of coxae 1±3 shortest. Gnathopods similar, small, second pair slightly larger than ®rst pair; width ratios on articles 5 and 6 of both pairs of gnathopods5 23:30 and 25:30, length ratios 5 55:60 and 50:60. Gnathopod 1, article 5 elongate, ovate, posterior margin rounded, long. Gnathopod 2, article 5 medium length, shorter than in ®rst pair, posterior margin evenly rounded, medium in length. Gnathopods 1 and 2, palmar humps large, palms oblique.

Peraeopod 4 slightly stouter than peraeopod 3 especially on articles 4 and 5. Peraeopods 3 and 4, facial setal formula on article 4 5 5 and 5, parallel to apex, on article 5 5 7 and 8; main spine of article 5 extending 80% on article 6; article 5 without proximoposterior spines; spine formula of article 6 5 51 8 and 51 9 plus mid-distal smaller spine, some spines long; dactylus with weak acclivity, apparently with a fully immersed nail, mid-facial plumose setule placed distally. Coxae 5±7, posteroventral seta formula5 6-5-5. Peraeopods 5 and 6, articles 4 and 5 of medium width, facial spine rows sparse. Peraeopods 5±7, facial ridge formula of article 2 5 0-1-1; width ratios of articles 2, 4, 5, 6 of peraeopod 5 5 70:40:32:16, of peraeopod 6 5 110:49:32:18, of peraeopod 7 5 130:34:30:13; length ratios of peraeopod 5 5 122:52:46:4 1 (right side) and 58:65:70 (articles 4, 5, 6 of left side), of peraeopod 6 5 138:98:70:105, of peraeopod 7 5 152:43:36:49. Peraeopod 7, article 2 reaching middle of article 5, posterior margin with about nine small serrations, medial apex of article 6 with three digital processes (extremely di cult to observe). Peraeopods 5±7, dactylus slender, long, with sharp acclivity, mid-facial plumose setule placed proximally and posteriorly.

Gills on coxae 2±7, those of coxae 6 and 7 small. Oostegites thin, long and setose, present on coxae 2±5.

Pleopods ordinary, as illustrated. Epimeron 1, posteroventral corner acute, subquadrate, posterior margin almost straight, weakly undulate, with four setules, anteroventral margin with three setae medium in length, two of these plumose, posteroventral margin with two long plumose setae. Epimeron 2, posteroventral corner obtuse, posterior margin almost straight, with two setules, facially with seven plumose setae, posteriormost seta set vertically. Epimeron 3, posteroventral corner produced, posterior margin convex bearing three setules and distal cluster of six long setae, anteroventral margin with three setae medium in length, ventral margin with three short spines widely spread, situated on its posterior half.

Urosomite 1 with lateral setule at base of uropod 1 and mid-ventral group of setae, articulation line complete. Urosomite 3 not protuberant dorsally. Uropod 1, peduncle with three basofacial setae, four apicolateral spines, medially ®ve marginal spines and strong displaced spine; inner and outer rami with three and seven dorsomedial spines, respectively. Uropod 2, peduncle with six stout dorsal spines and two apical short spines medially; inner and outer rami with three and ®ve dorsomedial spines, respectively. Uropods 1 and 2, peduncle apicolateral corners without comb; rami with articulate but tightly ®xed apical nails. Uropod 3, peduncle with seven ventral spines and one medial spine; rami unequal in length, inner extending 80% on article 1 of outer ramus, apex carrying two long plumose setae, medial and lateral margins plumose setose apically; article 2 of outer ramus elongate, 0.25, bearing two plumose setae short and medium, medial margin of article 1 setose, lateral margin with four acclivities, spine formula 5 2-2-2-3-3, no seta present. Telson medium length, length-ratio5 105:93, almost fully cleft, each apex wide, medially rounded, shallowly excavate, with short lateral spine and medial longer spine separated by plumose setule, except left lobe with one spine and setule, dorsal surface of each lobe with two long spines medially and two plumose setules proximally.

Additional observations

Paratype, ovigerous female (body length ca 6 mm). Antenna 1, primary ¯agellum with 11 articles; accessory ¯agellum with 10 articles. Mandible, left incisor with four teeth and hump.

Holotype, male (body length approximately 7 mm). Rostrum almost reaching end of article 2 on antenna 1. Pigmented eyes large, ovate. Antenna 1, article 1 with distal patch of sensory setae medially; article 2, with nine ventral setae; primary ¯agellum with 12 articles, bearing one calceolus each on articles 2±7; accessory ¯agellum with eight articles. Antenna 2, articles 3 and 4 with dense brushes of sensory ®ne setae dorsomedially; article 4, facial spine formula5 3-4-4-2, dorsal margin with a few short spread setae hidden by pubescence, ventral margin with long and short setae, and one ventrodistal medium spine; article 5 much longer than article 4, with fewer and shorter setae than in female, with four dorsal sets of male setae and ®ve calceoli, ventrodistal apex with two thin spines, facial spine formula5 4; ¯agellum elongate, broken at article 31, bearing calceoli. Mandible, palp article 3 about 1.1 times as long as article 2; article 2 with three small inner setae and one longer inner seta medially.

Coxa 4 longer than wide. Peraeopod 5, article 2 narrower than in female; width ratios of articles 2, 4, 5, 6 5 61:44:40:20, length ratios5 100:45:60:62. Peraeopod 7, article 5 with two copulatory spines, slender, straight, subequal, slightly longer than article 6.

Epimera 1±3 broadened. Epimeron 1, posterior margin slightly convex, undulate, with six setules, anterior margin with six setae, decreasing in length anteriorly, posteroventral margin with two medium plumose setae. Epimeron 2, posterior margin almost straight, with large undulations and ®ve setules, facially as in female, anterior face and margin bearing seven medium plumose setae. Epimeron 3, posteroventral corner rounded, not produced, posterior margin strongly convex bearing two setules and distal cluster of ®ve long setae and one very short spine set proximally to this group, anteroventral face with four medium setae, ventral margin with seven short spines widely spread.

Uropod 1, peduncle with seven apicolateral spines, medially as in female, but stout displaced spine shorter; inner ramus ornamented with the same number of spines as in female and outer ramus bearing six spines. Uropod 2, peduncle with 10 longer dorsal spines; outer ramus with four dorsomedial spines. Uropod 3, peduncle with 10 ventral spines and laterally with spine and setule; inner ramus the same length of article 1 of outer ramus; spine formula on article 1 of outer ramus 5 2-2-1-1-1, setal formula5 0-0-1-1-1; medial and lateral margins of both rami plumose setose. Telson much longer than in female, each apex with three spines besides plumose setule; distal and lateral spines shorter than in female, and plumose setules near the base.