Tanystylum geminum Stock, 1954

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 : 42-43

Tanystylum geminum Stock, 1954

Fig. 18–19

Tanystylum geminum Stock, 1954: 120 .— Child 1979: 28. Stock: 13. Stock, 1982: 187. Stock 1986: 400. Müller 1990: 279. Müller 1992:45

Material. 19.— 2 fem. (gravid) ( SMF 1404 ), Thalassia , 5 l of substratum, 0.5–4 m, 27.VI.1985 . 1 fem. (gravid) ( SMF 1405 ), Thalassia , 5 l of substratum, 5.VII.1985 . 1 fem. (gravid) ( SMF 1406 ), Thalassia , 5 l of substratum, 9.IX.1985 . 1 male ( SMF 1407 ), Thalassia , 5 l of substratum, 8.XI.1985 . 2 males, 1 fem., 2 juv. ( SMF 1408 ), Thalassia , 5 l of substratum, 7.XII.1985 . 1 juv. ( SMF 1410 ), Thalassia , 5 l of substratum, 12.II.1986 .

24.— 2 males, 1 fem., 2 juv. ( ZMA 3387 ), Thalassia , 0.5–1 m, 8.XI.1985 . 1 juv. ( SMF 1411 ), Thalassia with corallinacean algae, 1 m, 21.I.1986 .

32.— 1 male ( SMF 1412 ), on brown algae (mainly Sargassum ) on rock, mesolittoral, 3.VIII.1985 .

34.— 1 fem. ( SMF 1413 ), on brown algae, Thalassia and hydroids, 0.5–2 m, 30.VII.1985 .

40.— 1 male (ov.), 5 fem. (gravid) ( SMF 1414 ), Thalassia , 1–3.5 m, 8.VIII.1985 .

43.— 1 male ( SMF 1415 ), Thalassia , 1–1.5 m, 25.II.1986 .

Description of male: Dorsal trunk outline circular, crurigers touching along their entire length, smooth and without any setae; all segments fused. Cephalon with two short antero-lateral setae above palp origin. Ocular process broader than high, eyes relatively large and distinctly pigmented. Abdomen relatively short, directed obliquely to the rear, with 4 short setae in its distal part; abdomen surpassing the 4 th crurigers by about 1/4–1/2 of its length. Proboscis relatively long, strongly narrowing in its distal third.

Cheliphores about 1/3 length of proboscis, fused in their median line, distally rounded and bearing 3–4 short setae. Palpus 4-articled, 2 nd article elongated; 4 th article two times as long as 5 th, bearing 6 ventral and 3 terminal spines. Oviger 10-articled; articles 4 and 5 elongated, of nearly equal length and bearing some short spines; articles 6–10 shortened, bearing some short spines.

Legs robust, all articles bearing conspicuously few short spines and setae; coxae 1 of all legs distallydorso-laterally with a few irregularly shaped (partly branched) tubercles with short spines; coxa 2 with some short lateral spines, some mounted on tiny tubercles; coxae 1–3 subequal in length; dorso-distal cement gland on femur forming short and distally narrowing tube; tibia1 and 2 subequal in length, with 2 flat roundish dorsal tubercles; tarsus as long as broad, 4 ventral spines; propodus moderately curved, with indistinct heel; proximal third of sole with 3 strong short spines; sole distally with 3 small spines and about 4 short setae; main claw feebly curved, half as long as propodus; auxiliaries nearly straight, 2/3 length of main claw.

In contrast to the brownish colouration of most other species in this genus, T. geminum in our samples is whitish-yellow.

Measurements: Trunk length 0.47; width (across 2 nd crurigers) 0.50; length of abdomen 0.13; proboscis length 0.34. Leg 3: coxa 1, 0.12; coxa 2, 0.13; coxa 3, 0.13; femur 0.34; tibia 1, 0.28; tibia 2, 0.30; tarsus 0.06; propodus 0.28; main claw 0.14; auxiliary 0.09.

Female: In habitus like male, coxae 1 and 2 of all legs with some short setae distally. Oviger distinctly shorter than in male, in total more sparsely spinose and articles 4–5 more shortened.

Remarks: T. geminum is easily recognizable by its well-developed cheliphores, lack of tubercles and setae on the crurigers, and light colouration in the samples. This species is strikingly similar to Tanystylum bredini Child, 1970 , which is widely distributed in the Indo-Pacific. Distinctly differentiating characters are the shape of the proboscis, which is more robust in T. bredini and distally not so strongly narrowing, and shorter than the palps. Stock’s (1982: 187) material from Somalia, which he considered with some reservation as T. geminum , is comparable to the T. bredini which Müller (1990c: 68, Figs. 7–10 ) reported and figured from Kenya.

T. geminum predominantly colonized Thalassia stands in the research area, although to a lesser degree it was found also in association with algae. The depth range was from the mesolittoral to about 4 m. A single ovigerous female was found in VII only. Mature specimens were found during the course of the entire year except in the months III and X–XI.

Distribution: Atlantic coast of Mexico and Panamá ( Child 1979: 28), Florida and Puerto Rico (Stock 1975a: 983), Barbados ( Müller, 1992), Martinique (Bourdillon 1955: 587; Müller 1990d: 279), Bonaire, Isla Margarita, St. Martin and Jamaica ( Stock 1979: 13).

Figures

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 18. Tanystylum geminum Stock, 1954: A male dorsal, B another male dorsal, C female dorsal, D another female dorsal, E male lateral, F male palp, G male leg 3, H cement gland duct.

FIGURE 19. Tanystylum geminum Stock, 1954: A male oviger, B female oviger.