Nymphon aemulum Stock, 1975

Müller, Hans-Georg & Krapp, Franz, 2009, The pycnogonid fauna (Pycnogonida, Arthropoda) of the Tayrona National Park and adjoining areas on the Caribbean coast of Colombia 2319, Zootaxa 2319 (1), pp. 1-138 : 80-83

Nymphon aemulum Stock, 1975

Figs. 42–43

Nymphon aemulum Stock, 1975: 998 .— Stock 1986: 402. Material: 37.— 1 male, 3 fem. (1gravid), 2 juv. ( SMF 1512 ) on detritus, algae and hydroids, 6 m, 4.VI.1985.

42.— 4 juv. ( SMF 1513 ), coral rubble, 13 m, 28.II.1986 .

43.— 2 males (ov.), 1 adult lacking legs, 4 juv. ( ZMA 3372 ), Thalassia , 1–1.5 m, 25.II.1986 .

45.— 1 fem. (gravid) ( SMF 1514 ) from algae, hydroids and bryozoans on rock, 6–10 m, 25.IX.1985 .

Description of male and female: Dorsal trunk outline a long oval, all segments free, no tubercles and setae; crurigers separated by about 2/3 of their diameter, slightly longer than broad. Ocular process hemispherical, with feebly pigmented eyes. Oviger origins lateral, distinctly set off from first crurigers. Neck region short, proximally narrowing, but distally strongly enlarged. Abdomen a short and distally round tip, hardly longer than broad. Proboscis a long oval in outline, apically rounded, as long as first trunk segment.

Cheliphores slender, scape cylindrical with nearly parallel dorsal outline, scape not reaching over proboscis tip; chela narrow, proximally bearing several setae of varying length, most densely at base of immovable finger; movable finger rather strongly curved, fitted with 10 long slender teeth and one short distal tooth; immovable finger shorter and nearly straight, cutting edge with 8 long slender teeth. Palp 5-articled; 2 nd article the longest, 3 rd article 3/4 length of 2 nd, distally bearing several slender setae; distal article about half length of 2 nd, twice as long as 4 th; 4 th and 5 th article adorned with long sparsely distributed setae. Oviger of 10 articles; fifth article the longest, slender and distally enlarged to a club-like form, bearing crown of some sparsely setae; fourth article almost 3 times as long as diameter, 3/5 the length of fifth article; articles 6–10 progressively decreasing in length and diameter; 6 th article slightly curved and bearing numerous setae; the 4 distal articles with spines whose margins are plumose or serrated, according to the formula 14:12:13:12; terminal claw smooth, without teeth or serrations, feebly curved, about 2/3 length of terminal article.

Legs relatively slender and distal four articles especially with a dense cover of setae; coxa 2 twice as long as coxa 1 and coxa 3; femur and tibia 1 of same length, tibia 2—1.2 times longer; tarsus 1/3 as long as diameter, propodus slender and moderately curved; sole devoid of heel or spines, with a row about 12 slender setae; main claw robust, moderately curved, about 1/4 length of propodus, with some denticles on proximal inner margin; auxiliary claw more slender, of same length and curvature as main, with denticles on proximal part of inner margin.

Measurements of male: Trunk length 1.4, width 0.67 (across 2 nd crurigers); length of abdomen 0.13; length of proboscis 0.70; length of cheliphore scape 0.55; length of chela 0.51. Leg 3, lengths of articles: coxa 1—0.23; coxa 2—0.55; coxa 3—0.34; femur 1.15; tibia 1—1.15; tibia 2—1.43; tarsus 0.12; propodus 0.57; main claw 0.15; auxiliary claw 0.15.

Remarks: Nymphon macabou Müller, 1990 from Martinique and N. aemulum are very closely related. The latter species is distinguished mainly by its very slender habitus and the much more slender cheliphores. The chelae of both species are also different, those in N. macabou appear globose in dorsal view with short fingers, which are densely beset with robust teeth of different length (cf. Müller 1998d: 280, Figs. 6–13 ), while those in N. aemulum are slender with long fingers, cf Fig. 42 .

Nymphon aemulum avoids the surf zone, but otherwise colonizes waters down to about 37m (Stock 1975a: 998), showing no preference for particular substrata.

Distribution: Florida, Antigua, Virgin Islands, Puerto Rico, Barbuda, Surinam (Stock 1975: 998), Guadeloupe ( Stock 1986: 402) and now Caribbean coast of Colombia.

Figures

FIGURE 6. Ammothella appendiculata (Dohrn, 1881). A, male dorsal, B, male lateral, C, male cheliphore, D, female oviger, E, distal female oviger articles, F, male oviger, G, distal articles of male oviger, H, male palp, I, male leg 3, J, femur with eggs of female.

FIGURE 7. Ammothella exornata Stock, 1975: A male lateral, B male dorsal, C male cheliphore, D male palp, E female oviger, F male oviger, G five distal article of male oviger, H male leg 4, I female leg 4.

FIGURE 8. Ammothella gertrudae n. sp., subadult. A lateral, B dorsal, C cheliphore, D leg 3.

FIGURE 9. Ammothella gertrudae n. sp., subadult. A palp, B propodus and tarsus of leg 3.

FIGURE 10. Ammothella panamensis Child, 2004: A male dorsal, B male lateral, C male cheliphore, D male oviger, E distal 5 articles of male oviger, F female oviger, G distal 5 articles of female oviger.

FIGURE 11. Ammothella panamensis Child, 2004: A female leg 3 with ovules, B male leg 3, C tarsus and propodus of male leg 3, D male palp.

FIGURE 12. Ammothella marcusi Hedgpeth, 1948: A male dorsal, B male lateral, C male cheliphore, D female oviger, E distal 5 articles of female oviger.

FIGURE 13. Ammothella marcusi Hedgpeth, 1948: A male palp, B male leg 4.

FIGURE 42. Nymphon aemulum Stock, 1975, male: A trunk lateral, B trunk dorsal, C chela, D palp, E oviger, F distal oviger article with foliose spines and end claw.

FIGURE 43. Nymphon aemulum Stock, 1975, male: A leg 3, B propodus and tarsus of leg 3.