Haplopodia petersoni (Heron & Damkaer 1978)

Lubbockia petersoni

MATERIAL STUDIED (Tables 1, 2).—NE PACIFIC: 26 females, 0.95–1.06 mm, NP 10 et al. (including: holotype, 0.99 mm, NP 24, USNM 168497; 9 paratypes, 0.95–1.05 mm, NP 10, 24, 33, USNM 168499–168501); 12 males, 0.85–1.03 mm, NP 10 et al. (including: allotype, 0.99 mm, NP 24, USNM 168498; 4 paratypes, 0.91–0.95 mm, NP 10, 24, 33, USNM 168499–168501.

FEMALE.—Average length about 1.00 mm. Prosome about 1.8 times the length of the slender urosome, posterior corners rounded (Figure 21a,b).

Urosome first segment with slight transverse, sclerotized dorsoposterior ridge. Genital segment with areas of external genital apparatus posterior to midpoint on dorsal surface of segment, each area with 2 setules. Genital segment and each postgenital segment with fine spinules on posterior margins. Uropod with hyaline flap extending over base of dorsal seta.

Rostrum with sclerotized pattern accentuating a thickened rhomboidal ventral surface as shown in ventral view of cephalosome (Figure 21c). Protruding sclerotized process posterior to rostrum (Figure 21d), with vent near apex of process.

Antenna 1 with armature similar in number to that of L. minuta; variable rudimentary articulation between all segments, except distinct articulation between segments 4, 5.

Antenna 2 with armature similar to that of L. minuta, third segment with 4 terminal claws, 1 long seta, and 2 short setae (Figure 21c).

Labrum (Figure 21e) with free margin divided into 2 rounded posteroventral lobes, separated by a triangular vertex, from which arises a short hyaline hood.

Mandible (Figure 21f) with 2 adjacent, setulose outer elements; mandible blade with row of scalelike denticles on median edge; concave edge of base with a setulose element, spinules, and row of long setules.

Maxilla 1 (Figure 21g) and maxilla 2 (Figure 21h) with armature similar in number to that of L. minuta; ornamentation differs as shown in figures.

Maxilliped (Figure 21i) first segment with posterior protuberant process (Figure 21a,c). Second segment and terminal claw relatively reduced in length; incomplete suture separating terminal claw.

Leg 1 (Figure 21j) with inner spine on basis, third exopod segment with 3 short outer spines, proximal spine reduced. Leg 2 (Figure 22a) third exopod segment with 3 short outer spines, proximal spine reduced. Leg 3 (Figure 22b) inner edge of third endopod segment with 2 setae and 1 spine. Leg 4 (Figure 22c) inner edge of third endopod segment with 1 seta and 1 spine. Legs 2, 3 endopods terminate with a small vented projection; leg 4 endopod terminates with a vent between 2 most distal spines.

Leg 5 represented only by 1 seta on midlateral surface of first urosomal segment (Figure 21a,b).

Leg 6 probably represented by 2 hyaline setules in area of external genital apparatus.

MALE.—Average length about 0.93 mm. Prosome about 1.8 times length of slender urosome (Figure 22d,e).

Urosome with the 4 postgenital segments bearing fine spinules on posterior margins.

Rostral area and mouthparts, except antenna 1 and maxilliped, as in female; sclerotized process posterior to rostrum.

Antenna 1 with segmentation similar to that of female; armature similar to female except for addition of long esthete on segment 2 and 2 esthetes on segment 4; all esthetes elongate.

Maxilliped (Figure 22f) with small segment between second segment and slender, elongate claw.

Swimming legs and uropod segment 1 (Figure 22g) as in female, except narrower flange on swimming leg spines.

Leg 6 probably represented by posteroventral pointed flap on genital segment.

ETYMOLOGY.—It is a pleasure to name this species for Willis K. Peterson, Department of Oceanography, University of Washington, who designed and built the net for collecting deep plankton samples during hydrographic casts off the Washington coastal shelf. Mr. Peterson has generously made these samples available to us.

DISTRIBUTION.—Northeast Pacific Ocean (Tables 1, 2).