The Isopods of Abyssal Depths in the Atlantic Ocean

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132 ROBERT J. MENZIES Figure 29. A-E: Macrostylis bifurcatus, n. sp. A: dorsal view male holotype; B: first antenna; C: first paraeopod; D: fourth paraeopod; E: apex of male first pleopod. F-G: Macrostylis minutus, n. sp. F: dorsal view female holotype; G: female first antenna. H-M: Macrostylis bipunctatus, n. sp. H: dorsal view male holotype; I: third paraeopod; J: first paraeopod; K: maxilliped; L: first and second antenna; M: apex first pleopod. with sensory organ. Pleonal lateral margin not constricted in front of uropods; hind margin produced pointed, devoid of plumose setae. First antenna with four articles (female). Measurements: Holotype female length 2.5 mm., width pleon 0.4 mm. Type locality: North Atlantic, L.G.O. Biotrawl No. 234, two female paratypes, cat. no. 1-114. Distribution: Known also from L.G.O. Biotrawl No. 231, ten females, cat. no. 1-115, and L.G.O. Biotrawl No. 232, one female, cat. no. 1-111. Affinities: This species resembles the Pacific M. hadalis Wolff except that the first peraeonal somite is shorter than the second, rather than longer. Macrostylis bipunctatus, new species Figure 29 H-M Synonyms: None. Diagnosis: Cephalon narrower in front than rear, front rounded. Peraeonal somite 4 as wide as somites 3 and 5. First and second peraeonal somites subequal
in length; postero-lateral angles acute. Uropoda missing. Dorsum of pleon with pits above uropodal insertion. Apex of male first pleopods each with a stout recurved spine at lateral margin and six apical setae. Apexofpleon devoid of plumose setae. Pleonal lateral margin entire, not constricted in front of uropods; apical margin convex devoid of plumose setae. First antenna with only three articles (male). Measurements: Holotype male length 2.5 mm., width pleon 0.4 mm., allotype female length 2.1 mm., width pleon 0.4 mm. Type locality: South Atlantic, L.G.O. Biotrawl No. 12, types plus three fragments, cat. no. 1-119. Distribution: Taken also from the South Atlantic Type genus: Nannoniscus G. O. Sars. Diagnosis: Peraeopods not modified (flattened) for swimming but with plumose setae. Uropoda with peduncle, usually biramous. Peraeonal somites all of similar length; first free from cephalon. Maxillipedal palp with last two articles narrow; others equal width of endite. Dactyl of peraeopods with two terminal claws. Molar process of mandible reduced to a short setiferous lobe. Composition: This family contains Nannoniscus Richardson, Austroniscus Vanhoffen, and Nannoniscoid.es Hansen. These are distinguished from one another in the following key: A KEY TO THE GENERA OF NANNONISCIDAE 1. First antenna with a bulbous organ attached to distal article Nannoniscus 1. First antenna normal, without bulbous organ . . 2 2. Last two peraeonal somites incompletely fused Nannoniscoides 2. Last two peraeonal somites entirely separated Austroniscus The first two genera are represented by abyssal species. It is highly probable that Nannoniscella Hansen, 1916, is a synonym of Austroniscus Vanhoffen, 1914. Genus: NANNONISCOIDES Hansen, 1916 Type species: Nannoniscoides angulatus Hansen, 1916, pp. 86-87, PI. VIII. Diagnosis: Nannoniscidae with last two peraeonal somites incompletely fused. Pleon with single somite. Uropoda biramous. First antenna normal, without a bulbous organ attached to last article. This genus contains only the type, from 702 fathoms in the North Atlantic, and the new abyssal species described herein from the South Atlantic. ABYSSAL ATLANTIC ISOPODS 133 Family: NANNONISCIDAE at L.G.O. Biotrawl No. 51, one female, two fragments, cat. no. 1-51; L.G.O. Biotrawl No. 52, sixteen specimens, cat. no. 1-198; L.G.O. Biotrawl No. 53, one male, cat. no. 1-189; and L.G.O. Biotrawl No. 217, one female (with statocysts, and perhaps a distinct species). Affinities: This species is closely allied to M. galatheae Wolff, but has the postero-lateral angles of the cephalon pointed, not rounded. Macrostylis species indeterminable Indeterminate species of Macrostylis were taken from L.G.O. Biotrawl no. 53, three fragments. Nannoniscoides hirsutus, new species Figure 30 Synonyms: None. Diagnosis: Nannoniscoides, with a laterally serrated pleon. Body hirsute and densely reticulate. Cephalon three times as broad as the distance between the anterior ends of the cephalic keels. Antero-lateral angles with a stout seta on second somite, none on first or third. First peraeonal somite wider than cephalon; last two peraeonal somites pointed at lateral border. Uropodal endopod slightly shorter than exopod. Antero-lateral processes of cephalon not reaching frontal border. Apex of male first pleopods with tubular lateral expansion and each apex with three setae. Measurements: Holotype male length 1.2 mm., width pleon 0.4 mm. Type locality: South Atlantic, L.G.O. Biotrawl No. 12, type only, cat. no. 1-122. Distribution: Known only from type locality. Affinities: This species may be distinguished from N. angulatus Hansen by the fact that the first peraeonal somite is wider than the cephalon, not narrower. Genus: NANNONISCUS G. O. Sars, 1869 Type species: Nannoniscus oblongus G. O. Sars Synonyms: Nannoniscus G. O. Sars, 1869; — Hansen, 1916, pp. 87-89. Diagnosis: Nannoniscidae with last two peraeonal somites incompletely fused. Pleon with a single somite. Uropoda biramous. First antenna short, with a bulbous organ attached to last article. This genus contains 15 described species. Twelve of these were desccribed by Hansen (op. cit.); Vanhoffen (1914) described two species, and G. O. Sars described one.
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SUMMARY 83 INTRODUCTION 84 Material
Page 3: Family: Munnidae 172 A Key to the G
Page 6 and 7: In this paper the marine isopods of
Page 8 and 9: 86 ROBERT J. MENZIES Hansen (1897)
Page 10 and 11: 88 ROBERT J. MENZIES 90. Eurycope g
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Page 14 and 15: 92 two specimens (both larvae, one
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Page 20 and 21: 98 ROBERT J. MENZIES Affinities: Th
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Page 24 and 25: 102 ROBERT J. MENZIES Figure 10. A-
Page 28 and 29: 106 ROBERT J. MENZIES and peraeonal
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Page 52 and 53: 130 Macrostylis setifer, new specie
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Page 60 and 61: 138 ROBERT J. MENZIES Nannoniscus l
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Page 70 and 71: 148 below these spines the lateral
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Page 74 and 75: Figure 41. A-E: C: uropod; D: male.
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Page 78 and 79: 156 LIST OF ILYARACHNA SPECIES Spec
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182 ROBERT J. MENZIES Figure 62. A-
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184 ROBERT J. MENZIES Genus: THAMBE
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186 ROBERT J. MENZIES The three sub
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188 Uropodal rami blunt, endopod on
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190 ROBERT J. MENZIES Figure 69. Gl
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192 ROBERT J. MENZIES Measurements:
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194 ROBERT J. MENZIES possible. Thi
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LIST OF ATLANTIC ABYSSAL BIOLOGICAL
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198 ROBERT J. MENZIES Haploniscus (
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200 ROBERT J. MENZIES Eurycope (Ind
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LIST OF OTHER ABYSSAL ATLANTIC AND
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204 ROBERT J. MENZIES Haplomesus qu
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206 ROBERT J. MENZIES Crustacea Iso
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The Isopods of Abyssal Depths in the Atlantic Ocean

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