Nesippus nana Cressey 1970

Nesippus nana

MATERIAL.—Nine collections from gill arches of Carcharinus milberti. Holotype (USNM 128494) and 10 paratype (USNM 128495) collected 20 December 1966 at Sarasota, Florida.

FEMALE.—Body form as in Figure 39. Total length 3.77 mm (3.68–3.83 mm) and greatest width 2.12 mm (2.03–2.18 mm) based on an average of 5 specimens. Cephalon wider than long (2.10 × 1.58 mm in 1 specimen). Dorsal surface of cephalon border with conspicuous papillae, each bearing short hair (Figure 40). First thoracic segment fused with cephalon. Segments 2–4 free. No dorsal plates present on segment 4 and not expanded laterally. Abdomen 1-segmented, wider than long (650 μ × 472 μ). Genital segment baglike and about one-half total length, longer than wide (1.58 × .90 mm). Caudal rami (Figure 41) extending beyond posterior edge of genital segment, longer than wide (336 μ × 207 μ), bearing 5 setae, all but one of which is naked; short row of fine spinules along posterior portion of inner edge.

Oral area as in other species of genus. Adhesion pads associated with first antenna, second antenna, and maxilliped; maxilliped pad lateral to mouth tube and very conspicuous. First antenna (Figure 42) 2-segmented, 6 terminal spines of first segment with bristles scattered over surface, all other spines and setae naked. Second antenna (Figure 43) with clawlike terminal segment bearing single seta near midpoint along inner edge, weak articulation at this point suggesting fusion of 2 segments; penultimate segment with adhesion pad. Mouth tube and mandible as in other members of genus, mandible with 10 teeth. First maxilla (Figure 44) with group of 3 small setae near anterior end and short stout spine near outer midmargin. Second maxilla (Figure 45) with terminal segment in form of weak claw, tip bulbous, entire segment bearing longitudinal rows of fine spinules; penultimate segment bearing short spine and patch of hairs at distal end (Figure 46); an internal canallike structure present within segment and terminating at distal patch of hairs. Maxilliped (Figure 47) with terminal segment in shape of thumblike claw; when chela is closed, claw fits into depression on opposing segment.

Legs 1–4 biramose. Spine and seta formula as follows:

Leg 1

Leg 2

Leg 3

Leg 4

exo

end

exo

end

exo

end

exo

end

Seg. 1

I:0

0:0

I:1

0:1

I:1

0:1

IV

0

Seg. 2

IV:3

3

IV:5

7

IV:4

4

Leg 1 (Figure 48) exopod 2-segmented; spine on outer terminal corner of first segment with sub-distal accessory spinule, proximal 2 spines of terminal segment same, 2 terminal spines fingerlike, setae pinched off and shortened: endopod 2-segmented, terminal setae shortened. Leg 2 (Figure 49) rami 2-segmented; exopod with patch of spinules on outer margins of both segments, no accessory spinule on outer spines, setae shortened. Leg 3 (Figure 50) similar to leg 2 except for lack of spinules along outer edges of exopod segments and reduction in number of setae. Leg 4 (Figure 51) rami 1-segmented, surface of leg wrinkled and with many folds; exopod bearing 4 fingerlike spines distally, endopod unarmed except for small knob at tip. Leg 5 represented by 2 setae located lateral to abdomen. Leg 6 absent. Most setae present on legs 1–3 shortened. Those setae still entire have conspicuous constriction near base. Apparently distal portion breaks off at this point and seta is reduced to short blunt process. Blunt processes would function more effectively by aiding animal in movement over rough surface (gill bar) of host.

Egg strings long and straight.

MALE.—Unknown.

ETYMOLOGY.—The species name nana refers to small size of this species when compared with others of genus, except N. vespa.