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Some New Zealand Parasitic Copepoda of the Family Anthosomidae



Female (figs 1-13)

Overall length 6.5 mm - 6.8 mm.

Cephalothorax as wide as long (1.27 mm - 1.73 mm × 1.37 mm - 1.80mm), narrowing anteriorly to three-quarters this width, anterior margin curved, with small page 3 medial bulge; antennae colaterally on a frontal area, one-sixth length of cephalothorax, which is marked by a transverse groove; posterior margin of cephalothorax marked by a dorsal ridge which is highest medially, posterolateral angles of cephalothorax rounded. Cephalothorax separated from remaining thoracic segments by a very short neck.

Second and third thoracic segments fused, their junction marked by a groove; second segment four-fifths width of third, combined length three-quarters third segment segment width (second segment width 1.75 mm - 1.90 mm, third segment width 1.95 mm - 2.47 mm, combined length 1.20 mm - 2.26 mm), both segments rounded laterally.

Fourth thoracic segment partially fused with third, but separated by deep lateral grooves, a little longer than wide (3.42 mm - 4.16mm × 2.89 mm - 4.40mm), widest just before rounded posterior margin, narrowing to less than half this width anteriorly, posterior margin with a very shallow V-shaped notch medially. Segment slightly less than half length of combined plate and segment, largely hidden in ventral view by the lamellar fourth pereiopods.

Genital segment subovate, length three-fifths width (0.34 mm - 0.61 mm × 0.78 mm - 0.95 mm), entirely hidden in dorsal view by the plate of the fourth segment, and in ventral view by the fourth pereiopod.

Abdomen subrectangular, angles broadly rounded, as wide as long (0.41 mm - 0.45 mm × 0.33 mm - 0.52 mm), bearing the caudal laminae posterolaterally.

Caudal laminae with rounded proximal margin, narrowing to a point distally, width two-fifths length (0.72 mm - 0.88 mm × 0.29 mm - 0.35 mm), plate of fourth thoracic segment reaching beyond caudal laminae for a distance approximately equal to their length.

Egg strings many times length of animal, eggs uniserial, egg strings complexly coiled between plate of fourth thoracic segment and fourth pereiopod.

First antenna without obvious segmentation, basal width two-fifths length, extending laterally, distal third at right-angles to basal portion, extending posteriorly, proximal width of this section one-third basal width, narrowing distally to a point, with setae over distal fifth; outer margin of this section with four setae, three sparsely plumose, inner margin with two setae, and a further three setae on blunt tip.

Second antenna of two segments, segments subsequal in length, first segment, basal width two-thirds length, narrowing to two-thirds this width distally, with a small seta on outer margin near outer distal angle; second segment a sharply curved claw, basal width half length, narrowing steadily to a sharp point.

A small seta (0.2 mm in length) situated on a raised boss is found between the bases of the first and second antennae, and may correspond to the chitinised lappet in Anthosoma crassum.

Mouth tube small and very narrow distally.

Mandibular palp in two parts, medial part half length of lateral part, width half length, with a distal process one-third its length, width half length, rounded distally, with a seta near its base (hidden by distal protuberance in fig. 8); lateral part rising from a broad subrectangular base, width half length, rounded distally, with one heavy spine, one slender seta, and one blunt spine or small protuberance borne distally.

Maxilla of two segments, second half length of first, width of first two-sevenths length, rounded distally, width of second one-third length, rounded distally; second segment bears distally a small subsemicircular projection, one-eighth segment length, outer margin straight and dentate, a small flange surrounding part of its base.

page 4

Paralernanthropus foliaceus (Goggio, 1905) female:
fig. 1: dorsal view; fig. 2: lateral view; fig. 3: ventral view; fig. 4: first antenna; fig. 5: distal end of first antenna further magnified; fig. 6: seta found between first and second antennae; fig. 7: second antenna; fig. 8: madibular palp; fig. 9: maxilla; fig. 10: distal process of maxilla further magnified; fig. 11: maxilliped; fig. 12: first pereiopod; fig. 13: second pereiopod.

page 5

Maxilliped of two segments, second segment three-quarters length of first, first segment half as wide at the base as long, narrowing and rounded distally, with a raised area near midpoint of inner margin against which claw-like second segment closes; second segment, basal width two-fifths length, curving, particularly near base and tip, narrowing gradually to a sharp distal point.

First pereiopod biramou, each ramus of one segment; basipod swollen, subovate, width twice length, rami situated near inner distal angle, exopod half basipod length, endopod two-thirds exopod length: exopod a little longer than wide, outer margin a little longer than inner, with five flattened spines on distal margin; endopod as wide as long, rounded distally, bearing a single distal seta.

Second pereiopod biramous, each ramus of one segment, basipod swollen, semicircular, length half width, with a singe seta on a raised boss near outer distal angle, rami borne on inner part of distal margin; rami subequal in length, half basipod length; exopod rounded distally, width two-thirds length, with about seven very small spines around distal margin; endopod with basal width subequal to length, narrowing and rounded distally, with several small spines and one large spine on distal region.

Third pereiopod without rami, a flattened lamina, curved into a semicircle so that lateral margins are directed posteriorly, so that total length is about one-fifth body length, rounded anterior margin raised from body by a sublinear margin two-thirds anterodistal length of appendage.

Fouth pereiopod flattened lamellae, three-quarters body length, two-fifths as wide as long, one-third this width basally, distal half bifurcate, each branch narrowing distally to a point, outer branch a little longer than inner; the fourth pereiopods overlap in the midline so as to hide in ventral view much of the fourth thoracic segment, all of the genital and abnominal segments, and the egg strings. Male (figs. 14-24).

Overall length 3.20 mm and 4.82 mm.

Cephalothorax, width four-fifths length (1.45 mm and 1.48 mm - 1.23 mm and 1.17 mm), subovate, antennae borne laterally on a frontal area, marked by dorsal grooves, anterolateral angles rounded, two-fifths cephalothorax length, four-fifths as wide as long, shorter ventrally; posterior margin of cephalothorax an entire curve.

All remaining segments fused but second and third segments distinguished by lateral grooves, posterior margin of third segment by posterior termination of pereiopods. posterior termination of fourth segment by termination of fourth pereiopod and by lateral grooves, posterior margin of genital segment by slight grooves and by the disparity in width between the genital segment and abdomen.

Second thoracic segment subovate, length one-tenth width (0.08 mm and 0.09 mm × 0.75 mm and 0.82 mm).

Third thoracic segment subrectangular, the lateral margin between the base of the pereiopod and the second segment bulging laterally and curved, as long as wide (0.83 mm and 0.80 mm × 0.81 mm and 0.92 mm).

Fourth thoracic segment subrectangular, length half width (0.57 mm and 0.54 mm × 0.86 mm and 0.95 mm).

Genital segment subrectangular, posterolateral angles rounded, length half width (0.33 mm and 0.28 mm × 0.61 mm and 0.58 mm).

Abdomen subrectangular, length three-quarters width (0.22 mm and 0.17 mm × 0.29 mm and 0.22 mm) slightly narrower anteriorly.

page 6

Paralernanthropus foliaceus (Goggio, 1905) male:
fig. 14: dorsal view; fig. 15: ventral view of cephalothorax, second and third thoracic segments; fig. 16: tip of first antenna; fig. 17: seta from between first and second antennae; fig. 18: mouth tube and mandibular palp; fig. 19: mandibular palp; fig. 20: maxilla; fig. 21: maxilliped; fig. 22: first pereiopod; fig. 23: second pereiopod; fig. 24: genital segment, abdomen and caudal laminae.

page 7

Caudal laminae attached to lateral part of posterior margin of abdomen, basal width one-third length (0.45 mm and 0.40 mm × 0.12 mm and 0.13 mm) narrowing slightly distally, distal margin rounded, not pointed as in female.

Appendages as in female except that the maxilla bears a flange along outer margin of second segment, and a second smaller process on inner margin near distal process, the spines on the exopod of the second pereiopod are better developed than in the female and the third and fourth pereiopods are transformed into laterally projecting cylindrical processes fused to their respective thoracic segments. Third pereiopod projecting laterally from posterior half of third thoracic segment, length two-fifths body length, basal width one-quarter length, narrowing distally, distal margin rounded, posterior margin with a small pointed branch, one-seventh distance from base, which may represent the endopod.

Fourth pereiopod almost as long as body, extending posterolaterally from fourth thoracic segment, basal width one-ninth length, dividing one-seventh distance from base into two branches, inner branch two-thirds length of outer branch, both branches tapering gradually to a blunt point.