Other formats

    Adobe Portable Document Format file (facsimile images)   TEI XML file   ePub eBook file  

Connect

    mail icontwitter iconBlogspot iconrss icon

Some Amphipoda, Isopoda and Tanaidacea from Cook Strait

Family Arcturidae

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.

page 14
Pseudidothea richardsoni n.sp. Female.

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.

Pseudidothea richardsoni n.sp. Female.

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.

page 15

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).