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Some Amphipoda, Isopoda and Tanaidacea from Cook Strait
Sub-Order Valvifera
Sub-Order Valvifera
Family Arcturidae
Astacilla levis Thomson & Anderton, 1921. (Figs. 50–66).
Astacilla sp. Thomson & Anderton, 1921: 114–115, text-fig.
Body. Smooth and whitish: head anteriorly rounded, fused with 1st thoracic segment, segmentation indicated only by distinct groove with short incision at base of groove ventrally. Eyes black, large, subtriangular. Head and 1st 3 segments about ¾ length 4th thoracic segment, 2nd and 3rd segments subequal and each slightly shorter than 1st; 4th barely shorter than remaining thoracic and abdominal segments combined. Abdominal segments smooth, fused, segmentation indicated only by slight ventral incisions, shallow grooves, 1st especially faint. Pleotelson fused, defined only by shallow groove.
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Pseudidothea richardsoni n.sp. Female.
Fig. 74.—Adult female, dorsal view. Fig. 75.—Adult female, side view. Fig. 76.—Antenna 1. Fig. 77.—Antenna 2. Fig. 78.—Antenna 2, flagellum. Fig. 79.—Maxilliped. Fig. 80.—Mandible. Fig. 81.—Maxilla 1. Fig. 82.—Peraeopod 1. Fig. 83.—Pleopod 1. Fig. 84.—Pleopod 2. Fig. 85.—Pleopod 3. Fig. 86.—Uropod.
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Pseudidothea richardsoni n.sp. Female.
Fig. 87.—Peraeopod 2. Fig. 88.—Peraeopod 7. Figs.. 89–90.—Peraeopod 7, left and right dactyli. Fig. 91.—Uropod.
Iathrippa longicauda (Chilton). Female.
Fig. 92.—Antenna 1. Fig. 93.—Maxilliped. Fig. 94.—Maxilliped, detail of endite. Fig. 95.—Maxilla 2. Fig. 96.—Pleopod 3. Fig. 97.—Uropod.
Antennae. First: Basal segment a little expanded, ovate. Second: Peduncle 2nd segment ¾ length 3rd; 3rd not ½ length 4th; 5th ¾ 4th; 3-segmented flagellum not 2/3 length 5th, has stout end nail; flagellar segments have double row of strong spine-teeth right along inferior surface. Peduncle segments have fine scattered setae on surface, scaled around bases of setae. Antennae as long as head and 1st 4 thoracic segments.
Mouth parts. Maxilliped: Has 2 coupling spines.
Peraeopods. First: Normal, claw absent. Second-Fourth: End segment has short but distinct terminal claw. Fifth: Dactylos has 2 end spines; inner margin has 4–5 small corrugations proximally.
Pleopods. Male stylet on 2nd longer than pleopod rami, its proximal 3/5 relatively stout, distal 2/5 tapering to long slender seta-like process.
Uropods. Secondary ramus 1/3 to ½ length primary, much smaller, has 3 long plumose end setae, a smaller marginal seta.
Material Examined: Station BOL (VUZ. 43), 1 male, 12.5 mm; Station BOL (VUZ. 49), 1 male, 11mm (Slide Oc. 2), 1 female, 12 mm, ovigerous.
Distribution: Cook Strait; "trawl in 17 fathoms, about 3 miles east-southeast of Otago Heads, on the 30th December, 1919" (G. M. Thomson).
Discussion: Thomson and Anderton have briefly described and figured a species for which they suggest the name Astacilla levis might be used. I believe these specimens belong to their species, although they do not give a great deal of information. The species is easily distinguished from most other smooth-bodied Astacilla species, e.g. falclandica, kerguelensis, macilenta, algensis, deducta, vicaria and magellanica, with which it might otherwise be identified, by the three apical setae on the secondary ramus of the uropod.
Other New Zealand species are falclandica (Tattersall, 1921: 244), fusiformis (Hale, 1946: 185), and tuberculata (Thomson, 1879a: 416).
Family Pseudidotheidae
"Besides the usual male appendix on the endopodite of the second pair of pleopods, also the first pair of pleopods is in the male transformed into a copulatory organ. Body elongate. Segments of pleon all coalesced. Antennulae small. Flagellum consisting of one joint. Antennae strong, half as long as body. Peduncle 4-jointed, 1st and 2nd joint being coalesced, with the suture visible only from below, flagellum 2-jointed. Palpus of maxillipeds 5-jointed. Second-seventh pairs of pereiopods of nearly the same size and structure, with prehensile dactyl us. First pair much the shorter, its propodus and dactylus strong and armed with stout, in part serrated spines. Uropods with two small lamellae."
—Ohlin.
Genus Pseudidothea Ohlin, 1901.
"Head fused with the first segment of the pereion, being separated from the latter only by a faint groove. Eyes small, situated laterally. Coxae developed as incomplete, not very distinct, rings around the proximal ends of the basipodites of the second to seventh pereiopods. All segments of abdomen fused into one piece. Antennae with a two-jointed flagellum. Maxillipeds with a five-jointed palp. First pair of pereiopods prehensile. Penis cleft distally. Second male pleopod with the exopodite transformed and traversed by a diagonal channel. Uropods with two branches, the 'secondary' branch being about three-fourths the length of the lateral one and provided with a single large seta at the tip."
—Nordenstam.
Pseudidothea richardsoni n.sp. (Figs. 74–91).
Diagnosis: Antenna 2, last 3 segments of peduncle have inferior margin well supplied with long strong spine-setae; peraeopods, 2nd segments lack marginal tubercles; uropod, primary ramus has 3 plumose setae distally.
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Iathrippa longicauda (Chilton). Female.
Fig. 98.—Adult female. Fig. 99.—Antenna 1. Fig. 100.—Maxilla 1. Fig. 101.—Mandible. Fig. 102.—Peraeopod I. Fig. 103.—Peraeopod 1, dactylos. Fig. 104.—Peraeopod 7. Fig. 105.—Peraeopod 7, dactylos. Fig. 106.—Pleopod 2. Fig. 107.—Operculum.
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Jaeropsis palliseri n.sp. Male.
Fig. 108.—Adult male. Fig. 109.—Maxilla 1. Fig. 110.—Mandible. Fig. 111.—Peraeopod 1. Fig. 112.—Peraeopod 1, dactylos. Fig. 113.—Peraeopod 7. Fig. 114.—Peraeopod 7, dactylos. Fig. 115.—Pleopod 2. Fig. 116.—Pleopod 2, detail. Fig. 117.—Pleopod 3.
fur of sediment; body segments mildly tuberculate, the tubercles really little more than suggested (and a little exaggerated in the figures). Limbs, pleon, and uropods quite setose and furred.Antennae. First: First segment subrectangular, almost as wide as long, almost as long as 2nd and 3rd combined; slightly longer than 4th which has end tuft of about 6 flaccid sensory setae. Finely furred margins, a few plumose setae, especially on 2nd segment. Second: Peduncle, 2nd segment 2/3 length 3rd, 3rd slightly shorter than subequal 4th and 5th, the last 2 having a few fine surface setae, the last 3 having strong spines on inferior margins. Flagellum short, 1st segment with long end seta inferiorly, 2nd with terminal "nail" spine as long as itself. Furred.
Mouthparts. Maxilliped: Endite furred, quite wide, almost ovate, rounded end margin has about 4 plumose setae; no sign of coupling hooks. Palp 1st 2 segments short, 3rd ovate, as long as 4th and 5th combined, has about 5 short plumose setae on inner margin; 4th slender, has 4–5 plumose setae on inner margin, one on outer distal angle; 5th a short dome ½ length 4th, has about 4 terminal plumose setae. Mandible: Left has lacinia, 3 spines in spine row; molar process short, distally wide with jagged end margin, 4 setae in middle of end margin. Maxilla 1: Outer plate has 11 plumose setae; inner plate narrow, slightly shorter, has 3 plumose end setae.
Peraeopods. First: Short, strong, ischium about ½ basos length, carpus as long as ischium, merus shorter; all 4 segments finely furred; ischium has 1 spine on posterior margin, merus about 4, carpus about 7 denticulate spines. Propod, ovately triangular, as long as basos, width ½ length, 4 strong denticulate spines on posterior margin, several rows of spines on surface distally. Dactylos strong, ½ propod length, has 2 strong denticulate spines on posterior margin, a strong end spine-claw. Second: Basos and carpus subequal in length, merus slightly shorter, ischium still shorter; propod almost as long as merus plus carpus; segments furred; dactylos ½ propod length, has strong end-claw, a few fine setae. Ischium has 2 strong spine-setae on posterior margin, merus 4, carpus 6; propod has 2 very strong ones on posterior margin, about 4 rows of 2–3 slimmer spines down median surface. Third: Like 2nd. Fourth-Sixth: Like 7th. Seventh: Basos and propod subequal, ischium, merus and carpus successively shorter, carpus about ½ propod, all furry with a few fine setae on margins; dactylos claw truncate on left peraeopods, sharp on right.
Pleopods. First: Peduncle has 3 coupling spines; one ramus about ½ length other which has 4 long end setae. Second: Rami subequal, subrectangular, strongly fringed with plumose setae. Third: Ovate-lanceolate, one ramus little larger than other, a few fine marginal setae; one stronger end seta on shorter ramus.
Uropods. Furry; subtriangular, ramus very short, ovate-triangular, has 3 plumose setae distally; secondary about 2/3 as long, narrow, has an equally long and slightly curved strong end spine.
Material Examined: Station BOL (VUZ. 43), 1 female, ovigerous, 4 9 mm long, 1.2 mm wide.
Holotype: Slides Oc. 6.
Distribution : Cook Strait.
Discussion: This specimen is very close to Ohlin's Pseudidothea bonnieri, the type of the genus and family. However, there are sufficient small differences, I feel, to warrant establishing a separate species—the second in the family—and the finding of a male may reveal further differences in the pleopods from P. bonnieri.
The most significant features are the end setae of the main uropod ramus: the lack of tubercles on the peraeopods; and the strong spination of the second antennae.