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Zoology Publications from Victoria University of Wellington—Nos. 49 to 51

Description

Description

Female (figs. 27-38).

Overall length 8.4 mm-9.3 mm.

Cephalothorax subovate, width four-fifths length (1.7 mm-2.0 mm × 1.4 mm-1.5 mm), median third of lateral margins sublinear.

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Nemesis lamna vermi Scott, 1929 from Cetorhinus maximus. Female—fig. 27: dorsal view; fig. 28: anterior, ventral view; fig. 29: first antenna; fig. 30: second antenna; fig. 31: mouth tube and mandibular palp; fig. 32: maxilla; fig. 33: tip of maxilla; fig. 34: maxilliped; fig. 35: first pereiopod; fig. 36: second pereiopod; fig. 37: third pereiopod; fig. 38: endopod of fourth pereiopod.

Nemesis lamna vermi Scott, 1929 from Cetorhinus maximus. Female—fig. 27: dorsal view; fig. 28: anterior, ventral view; fig. 29: first antenna; fig. 30: second antenna; fig. 31: mouth tube and mandibular palp; fig. 32: maxilla; fig. 33: tip of maxilla; fig. 34: maxilliped; fig. 35: first pereiopod; fig. 36: second pereiopod; fig. 37: third pereiopod; fig. 38: endopod of fourth pereiopod.

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Second thoracic segment a little longer than wide (1.6 mm-1.7 mm × 1.4 mm-1.7 mm), widest posteriorly, two-thirds this width anteriorly, anterior angles rounded, posterior angles broadly rounded.

Third thoracic segment similar in shape to second, but a little wider than long (1.35 mm-1.7 mm × 1.5 mm-1.7 mm).

Fourth thoracic segment similar in shape to second and third except that it is not narrowed as strongly anteriorly, as long as wide (1.5 mm-1.7 mm × 1.5 mm-1.8 mm).

Fifth thoracic segment subrectangular, length two-thirds width (0.9 mm-1.1 mm × 1.5 mm-1.6 mm), posterior angles rounded, anterior angles rounded and swollen anteriorly, separated from fourth thoracic segment by a short neck, about 1.1 mm in width.

Genital segment as wide as long (0.8 mm-0.9 mm × 0.8 mm-1.0 mm), lateral margins curved, bearing spermathecae which are about 0.4 mm in diameter laterally.

First abdominal segment subrectangular, length two-fifths width (0.2 mm-0.25 mm × 0.4 mm-0.5 mm).

Second abdominal segment subrectangular, length three-quarters width (0.3 mm-0.35 mm × 0.35 mm-0.4 mm), caudal laminae borne laterally on posterior margin.

Caudal laminae subrectangular, rounded distally, width half length (0.17 mm-0.20 mm × 0.07 mm-0.10 mm), with two spines and three very slender setae on distal margin.

Egg strings damaged or missing in most specimens, total length 16 mm and 25 mm in two specimens in which they are apparently undamaged.

First antenna apparently of fourteen segments, their relative lengths given by the ratio 18:6:3:3:4:2:3:4:3:4:4:3:4:7; all segments subrectangular, the distal segment rounded distally; first segment width half length; second segment length three-quarters width, with four setae on distal margin and two setae medially; third segment length two-fifths width, with one seta on outer distal angle, and one seta medially; fourth segment length two-fifths width, with one seta on distal margin; fifth segment length three-quarters width, with two setae on distal margin and two setae medially; sixth segment length half width; seventh segment length two-thirds width, with two setae on distal margin and one seta medially; eighth segment as long as wide, with one seta on distal margin; ninth segment length four-fifths width; tenth to twelfth segments as long as wide, tenth segment with one seta on distal margin; thirteenth segment width two-thirds length; terminal segment width one-third length, with about eight setae distally, and one further seta a little proximal to these.

Second antenna mouth tube, mandibular palp, maxilla and maxilliped as in N. l. lamna, except that the maxilliped appears to have one small additional seta on inner margin of claw-like second segment.

Second pereiopod as in N. l. lamna except that distal margin of second segment of exopod has six small spines and this segment is slightly longer and narrower, and second segment of endopod has four spines and one very small spine on distal margin.

Third pereiopod similar to second except that the second enodpod segment narrows slightly more distally, and the distal margin of the segment bears only two spines, the inner spines of the second pereiopod being replaced by a group of very small spines.

Fourth pereiopod similar to second except that spines of endopod second segment are spaced slightly further apart.

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Nemesis lamna vermi Scott, 1929 from Cetorhinus maximus. Male—fig. 39: dorsal view; fig. 40: anterior, ventral view; fig. 41: first antenna; fig. 42: second antenna; fig. 43: tip of maxilla; fig. 44: maxilliped; fig. 45: first pereiopod; fig. 46: second pereiopod; fig. 47: third pereiopod; fig. 48: fourth pereiopod; fig. 49: genital segment and abdomen, ventral view; fig. 50: tip of caudal lamina.

Nemesis lamna vermi Scott, 1929 from Cetorhinus maximus. Male—fig. 39: dorsal view; fig. 40: anterior, ventral view; fig. 41: first antenna; fig. 42: second antenna; fig. 43: tip of maxilla; fig. 44: maxilliped; fig. 45: first pereiopod; fig. 46: second pereiopod; fig. 47: third pereiopod; fig. 48: fourth pereiopod; fig. 49: genital segment and abdomen, ventral view; fig. 50: tip of caudal lamina.

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Male (figs. 39-50).

Overall length 6.7 mm-7.2 mm.

Cephalothorax shaped as in female (1.5 mm-2.0 mm × 1.4 mm-1.45 mm).

Second thoracic segment similar in shape to that of female but smaller (1.2 mm-1.4 mm × 1.25 mm-1.4 mm).

Third thoracic segment similar in shape to first, except shorter, length four-fifths width (0.9 mm-1.0 mm × 1.2 mm-1.3 mm).

Fourth thoracic segment similar to third but anterior angles more broadly rounded (0.9 mm-1.0 mm × 1.2 mm-1.3 mm).

Fifth thoracic segment, length half width (0.45 mm-0.6 mm × 1.0 mm-1.1 mm), narrowing to two-thirds this width anteriorly.

Genital segment subovate, as long as wide (1.15 mm - 1.3 mm × 1.15 mm-1.2 mm).

First abdominal segment subrectangular, length two-thirds width (0.4 mm-0.5 mm × 0.6 mm-0.8 mm), widest anteriorly, narrowing to two-thirds this width distally.

Second abdominal segment disc-shaped, lateral margins convex curves, length three-fifths width (0.2 mm-0.3 mm × 0.4 mm-0.45 mm).

Third abdominal segment subrectangular, lateral margins slightly distended, length three-quarters width (0.25 mm-0.35 mm × 0.3 mm-0.4 mm), caudal laminae borne laterally on distal margin.

Caudal laminae as in female.

First antenna apparently of thirteen segments, their relative lengths represented by the ratio—16:6:3:3:4:2:4:4:3:4:4:6:8; first segment, width two-fifths length, with one seta near outer distal angle; second segment a little wider than long, with one seta on distal margin and two setae medially; third segment length half width, with one seta on distal margin and one seta medially; fourth segment length two-fifths width, with one seta medially; fifth segment length three-quarters width with one seta on distal margin and five setae on outer margin; sixth segment length half width, with one seta near distal margin; seventh segment, length two-thirds width, with two setae on distal margin; eighth segment, as long as wide, with two setae on distal margin; ninth segment length three-quarters width, with one seta near distal margin; tenth segment as long as wide, with one seta near distal margin; eleventh segment as long as wide, with two setae near distal margin; twelfth segment width half length, narrowing slightly medially, perhaps composed of two indistinctly separated segments, with two setae medially; terminal segment, width one-third length, with about seven setae distally, and a further seta just proximal to these.

Second antenna, mouth tube, mandibular palp, maxilla, maxilliped and first pereiopod all as in female.

Second pereiopod as in female except as follows: first segment of exopod lacks spine on inner distal angle, second segment of exopod has only four spines on distal margin, and second segment of endopod has only three spines on distal margin.

Third pereiopod as in male of N. l. lamna except as follows: first segment of exopod has a spine on inner margin, second segment of exopod has one long spine and four short spines on distal margin, spine on inner margin of first segment of endopod is more slender, and second segment of endopod lacks the group of small spines near middle of outer margin.

Fourth pereiopod as in male of N. l. lamna except that second segment of endopod has only one small seta on inner margin.