Nymphon okudai Nakamura & Child 1991

Nymphon okudai

MATERIAL EXAMINED.—HOKKAIDO: SE of Kiritappu, 42°51.8′N, 145°25.6′E, 321–328 m, 10 Jul 1983 (l with eggs, holotype, USNM 234499); 42°51.8′N, 145°22.0′E, 216–224 m, 10 Jul 1983 (l with eggs, 1, 1 juv, paratypes, USNM 234500).

DESCRIPTION.—Size moderately large, leg span 67 mm. Trunk fairly compact, lateral processes separated by about their diameters or slightly less, slightly less than twice their diameters in length, with few short dorsodistal setae. Oviger implantation against first lateral processes directly ventral to ocular tubercle, which is rounded, as tall as wide. Eyes large, slightly pigmented, with prominent lateral sensory papillae. Neck moderately short, parallel sides not as long as crop. Proboscis cylindrical with slight median swelling, lips almost flat. Abdomen short, with distinct basal articulation, armed with few short distal setae.

Chelifores moderately large, scape as long as proboscis, armed with few lateral and distal setae and one dorsomedian seta as long as scape diameter. Chela palm cylindrical, expanded distally, armed with many short lateral and distal setae. Fingers slender, carried anaxially, as long as palm, very slightly curved except for well-curved overlapping tips. Immovable finger with 24–28 slender pointed teeth, movable finger with 27–28 similar teeth.

Palps moderately long, slender, third segment slightly longer than second, fourth about 0.75 as long as fifth, which is 0.85 as long as third. Third segment armed with few short lateral and ventral setae, fourth and fifth with many short lateral and ventral setae, none longer than segment diameter.

Oviger fourth and fifth segments subequal in length, slightly curved, fifth with very slight inflation distally bearing short setae. Eggs carried in ovoid cemented ball on fifth segment, each egg slightly less in diameter than the segment. Sixth segment long, over five times its diameter, slightly curved, armed with many short setae. Strigilis segments each shorter than last, armed with few dorsodistal setae, endal denticulate spines in the formula 18:13 :13 : 14, with a small, slightly curved terminal claw bearing 14–15 tiny closely spaced teeth. Denticulate spines very slender, with 1–2 larger lateral serrations and many tiny distal serrations per side.

Legs very slender, long, armed with few short dorsal and ventral setae, and 1 to several longer lateral setae on first coxae, first and second tibiae. Cement gland pores found only on femorae, numbering 19–23 per segment. Tarsus about 0.3 longer than propodus, both with few short dorsal setae, a row of very short sole spines of slightly varying lengths, none large. Claw fairly short, robust, well curved at tip, auxiliaries short, about 0.3 as long as main claw.

Female Paratype: Neck slightly longer than that of male, all measurements slightly larger. Terminal palp segment shorter in relation to fourth than that of male, chelae teeth fewer in number, while strigilis terminal claw bears 19 tiny teeth continued to claw tip, and chelae teeth count is 22 for immovable finger and 18 for movable finger.

MEASUREMENTS (holotype, in mm).—Trunk length, 4.78; trunk width (across 2nd lateral processes), 2.84; proboscis length, 1.74; abdomen length, 0.62; third leg, coxa 1, 0.72; coxa2, 2.54; coxa 3, 1.34; femur, 6.22; tibia 1, 7.6; tibia 2, 9.3; tarsus, 2.16; propodus, 1.52; claw, 0.62.

DISTRIBUTION.—The new species is known only from eastern Hokkaido, southeast of Kiritappu, in 216 to 328 meters.

ETYMOLOGY.—We are pleased to name this species for the late Dr. Shiro Okuda, Professor at Hokkaido University, for his pioneering work on the metamorphosis of a pycnogonid associated with hydromedusae.

slope