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Some Amphipoda, Isopoda and Tanaidacea from Cook Strait

Sub-Order Asellota — Family Parasellidae

Sub-Order Asellota
Family Parasellidae

Group Ianirini

Iathrippa longicauda (Chilton), 1884. (Figs. 92107).

Janira longicauda Chilton, 1884: 250, pl. 18, fig. 2a.

Thomson, 1889: 265–266.

Tattersall, 1921: 200, pl. 1, fig. 6.

Ianira (Iathrippa) longicauda, Nordenstam, 1933: 173–176, text-figs. 40 a–h.

Iathrippa longicauda Nierstrasz, 1941: 286.

Diagnosis (Female) : Anterolateral angles of cephalon more or less rounded, not significantly produced anteriorly; rostrum triangulate, reaching distal end of 3rd peduncle segment of antenna 2. Epimeral plates visible dorsally, between lateral angles of segments 2–4 of body, posterodistally on segments 5–7, Pleotelson margins smooth, setose, slight page 18 indication distally of rounded median lobe. Uropods longer than pleotelson, rami somewhat lanceolate, inner the longer.

Body. Somewhat flattened, white in preserved specimen. Lateral margins of body setose.

Antennae. First: Reaches ½ along 5th peduncle segment of antenna 2; distal flagellar segments have each a flaccid sensory seta; flagellum of 15 segments, segments not especially widened. Second: 1st 4 peduncle segments together a little shorter than 5th, have several strong spines and setae; 5th ¾ length 6th; 5th and 6th have 1–2 long spines on each margin, setae; 1st flagellar segment nearly ½ length last peduncle segment; flagellum of 55 or more segments; accessory scale on 3rd peduncle segment, reaches end of 4th, has 4 end spines, setae.

Mouth parts. Maxilliped: Has 3 coupling spines; endite distal margin has 8–9 plumose setae; 7 large bush-setae, small spine on inner distal angle, longer one on rounded outer angle. Palp, 1st 3 segments as wide as endite, inner distal angles setose, 4th and 5th segments slender, distally setose, 5th 1/3 length 4th; 4th as long as 2nd and 3rd combined. Maxilla 1: Inner plate has 4 strong setae, fine bristles; outer has 11 denticulate spines. Maxilla 2: Outer plate lappets have 4 end setae each; inner has numerous end setae. Mandibles: Lacinia present; spine row of 9 denticulate spines; mandibular process long, not narrowing but truncate, has upper angle produced a little in tooth, lower has slender spine and 5–6 plumose setae; a few minute teeth on surface. Palp of 3 segments, 1st and 3rd subequal, about 2/3 length 2nd: 1st has about 3 setae on distal angle; 2nd has about 7 strong denticulate spines, comb-scales on surface; 3rd has long terminal spine, row of about 20 denticulate spines on concave margin.

Peraeopods. First: Carpus and propod subequal, carpus broader but not noticeably ovate, width not 1/3 length; posterior margin has 11–12 spines, seta or two, otherwise entire; propod posterior margin has 7–8 spines, otherwise entire. Dactylos has 2 claws, setae. Seventh: Carpus barely shorter than propod. has about 3 spines, setae, anteriorly; propod has about 5 spines; dactylos as in 1st. Others: All dactyli have 2 claws.

Pleopods. Third has exopodite slightly longer than endopodite, of 2 segments; endopodite has 2 plumose setae distally on inner margin, one on outer.

Operculum. Ovate, distally rounded, margins have short fine setae.

Uropods. Outer ramus about 2/3 length inner; peduncle ½ inner, widening distally; peduncle and rami all strongly spined and setose.

Material Examined: Station GUL (VUZ. 54), 1 female, 8.5 mm (Slides Oc. 4).

Distribution: Cook Strait; Lyttelton Harbour (Chilton); "Terra Nova" Station 96, 7 miles E. of North Cape, 70 fathoms, bottom fauna, 1 ovigerous female, 4 5 mm (Tattersall, 1921); Campbell Islands, Falkland Islands, S. Georgia, Magellan Straits, W. Chile (cf. Nordenstam, 1933).

Discussion : This specimen agrees quite well with Chilton's original description, and with Nordenstam's supplementary details. Tattersall's figure is a little generalised and even inaccurate since he shows the epimeral plates as part of the lateral margins of the segments. It should be noted, however, that the dactyli in this specimen all have 2 claws whereas Nordenstam mentions 3.

I have followed Nierstrasz rather than Nordenstam in generic classification, not because of any strong views on the subject but because Nierstrasz's is the more recent paper.

Group Jaeropsini
Genus Jaeropsis Koehler

Jaeropsis palliseri n.sp. (Figs. 67–73, 108–117).

Diagnosis: Eyes near lateral margin. Anterolateral angles of cephalon bluntly rounded, not significantly produced anteriorly. Rostral process subrectangular, anterior margin somewhat sinuate. Maxilliped endite has 5 coupling spines. Distal angle of maxilliped palp 2nd segment not produced. Pleotelson margins smooth, entire. Exopodite of uropod has 1 segment. Body has purplish-brown pigmentation with white mottling on all segments, posterolateral portion of head and lateral angles of body somites unpigmented.

Body. Animal elongate, flattened, dorsally smooth, lacking noticeable setae. Cephalon wider than long. Frontal margin has shallow lateral concavities separated by central shallow, but more anteriorly produced, concavity, into which rostral projection fits. Eyes dorsal, a page 19 little in front of halfway. Peraeon has no epimeral plates visible in dorsal view. 1st and 2nd somites equally long, 5th shortest. Pleotelson wide, shield-like. Posterior median projection semi-acute, does not reach distally as far as tips of uropods.

Antennae. First: Of 6 segments, 1st as long as other 5, twice as wide, has scattered fine setae, 2 plumose sensory setae on distal angle. Last 2 segments have 2 elongate flaccid sensory setae each, a few fine setae. Second: Peduncle 5th segment about ¾ length 6th, both distally expanded on inner margin; outer and end margins and surface of 6th have fine setae; 6th segment of peduncle ¾ length 1st flagellar segment which is more than twice length remaining 5 flagellar segments; segments all setiferous, 1st especially on surface and outer margin.

Mouthparts. Maxilliped: Palp of 5 increasingly narrower segments, 1st short, 1/3 length 2nd, ¼ length 4th; 3rd almost twice length 1st and 5th; inner margins of 3rd and 4th bristled, a few setae especially on end of 5th. Endite has only about one distinct spine on inner concavity of end margin, but about 5 spine-teeth. Maxilla 1: Inner plate has 4 apical setae, outer 11 denticulate spines. Maxilla 2: Outer plate lappets have 4 apical setae each, inner plate also has 4. Mandible: Lacinia absent. Incisive part has 5–6 teeth, setal row of 9 setae; molar long and needle-like, damaged in mounted appendage. Palp of 3 segments, 1st slightly longer than subequal 2nd and 3rd; 2nd has 5 plumose setae distally, 3rd has 10–11 along inner margin.

Peraeopods. First: Dactylos has 2 claws, propod has 5 spines on posterior margin, most of margin and distal ¼ of carpus posterior margin finely tooth-combed. Seventh: Dactylos has 3 claws, propod posterior margin has 6 spines, is finely tooth-combed. Others: Have 3 claws like 7 th.

Pleopods. 1st in male has produced rounded posterolateral angles, medially produced setiferous end margin.

Uropod. Peduncle, wide, subrectangular, with rounded angles, end margin setose, medially excavate with small scale-like rami, both rami distally setose.

Material Examined: Station BOL (VUZ. 43), Holotype male, length 5.3 mm; width 1.4 mm.

Holotype: Slides Oc. 3.

Distribution : Cook Strait.

Discussion: According to Chilton (1912), young specimens of neo-zelanica (? = curvicornis; cf. Stebbing, 1905: 51–52, pl. XI.C) have several serrations on the pleon margins, older specimens have one serration. Since his material came from several localities, I am inclined to believe that he had more than one species; in any event, it appears that his material was different from the species described above. Nearest to J. palliseri are J. paulensis and J. lobata; the latter appears to be distinct in rostral process and, by inference from its possible identity with J. dubia (Menzies, 1951), in the uropods and other features.