Tanystylum hummelincki 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 : 44-46

Tanystylum hummelincki Stock, 1954

Figs. 20–21

Tanystylum hummelincki Stock, 1954: 122 . Stock 1986: 402.

Material: All series from station 8 (jetty piles).— 1 juv. ( SMF 1416 ), on corallinacean algae, exposed to light, 0–1 m, 21.IV.1985 . 1 male ( SMF 1417 ), on corallinacean algae and hydroids, exposed to light, 0–1 m, 24.IV.1985 . 1 male, 1 fem. (gravid), 1 juv. ( ZFMK), on poriferans and hydroids, shaded, 0–1 m, 25.IV.1985 . 2 males ( SMF 1418 ), on poriferans and hydroids, shaded, 0–1 m, 4.V.1985 . 1 male, 1 fem. (gravid) ( ZMA 3379 ), on algae and hydroids, exposed to light, 8.V.1985 . 3 males, 3 fem., 3 juv. ( SMF 1419 ), on algae and poriferans, exposed to light, 0–1 m, 10.V.1985 . 3 males, 5 fem. (3gravid), 11 juv. ( SMF 1420 ), on poriferans and hydroids, shaded, 0–1 m, 14.V.1985 . 1 fem. (gravid), 1 juv. ( SMF 1421 ), on poriferans and hydroids, exposed to light, 14.V.1985 . 1 fem., 1 juv. ( SMF 1422 ), on poriferans and hydroids, shaded, 16.V.1985 . 1 fem., 1 juv. ( SMF 1423 ), on poriferans and hydroids, 18.V.1985 . 2 males, 2 females (1gravid), 1 juv. ( INVEMAR), on poriferans and hydroids, 19.V.1985 . 2 males (1ov.), 1 fem., 1 juv. ( USNM), on hydroids and bryozoans, shaded, 1–3 m, 17.VI.1985 . 3 juv. ( SMF 1424 ), on detritus and Cnidoscyphus , exposed to light, 0– 1 m, 31.VII.1985 . 2 males, 1 fem., 1 juv. ( SMF 1425 ), on Cnidoscyphus , shaded, 0–1 m, 17.X.1985 . 1 fem. (ov.), 3 juv. ( MNHN), same locality, 24.XI.1985 . juv. ( SMF 1426 ), on different growth, shaded, 0–1 m, 17.XII.1985 . 4 males (2ov.), 1 fem. ( SMF 1427 ), on hydroids, shaded, 0–2 m, 1.II.1986 . 2 males (1ov.), 2 fem. ( ZSM), on poriferans and hydroids, shaded, 0–1 m, 14.III.1986 .

Description of male: Dorsal trunk outline circular, crurigers touching each other along their entire length; all trunk segments fused; cephalon with a short antero-lateral seta above palp origin; ocular process about 1.5 times as high as broad, terminating in acute tip. Eyes large, distinctly pigmented. First crurigers with small dorsal tubercle, crurigers 2–4 with small antero-lateral tubercle with one short distal seta. Abdomen relatively short, directed obliquely backwards and with about 5 short setae in its distal half; abdomen exceeding 4 th crurigers by ¼ of its length. Proboscis robust, distally markedly obtuse.

One-articled cheliphores relatively long, their bases separated, distally slightly narrowing and rounded, bearing 3–4 short setae. Palp 6-articled, the articulation between the short third and the longest fourth article accentuated; terminal article twice as long as fifth one, with about 15 setae in ventral, ventro-lateral and distal positions. Oviger 10-articled; articles 4 and 5 elongated, with some short setae; 5 th article 1.2 times length of fourth; 7 th article with distal rounded tubercle, bearing group of 6 setae; terminal article tiny with 2 flat denticulate spines.

Legs robust, articles with relatively few, mostly short spines and setae; coxae 1 of all legs with distal tubercle in antero-lateral, dorsal and postero-lateral positions; antero-lateral tubercles branched, with 2–3 distal setae; dorsal and the tiny postero-lateral tubercle rounded, frequently showing single seta only; coxae 2 and 3 of equal length, coxa 1 slightly shorter than these; cement gland on femur situated dorso-distally, short, slightly narrowed and tubiform terminally; tibia 1 and tibia 2 of equal length, barely longer than femur, with two dorsal flat tubercles; tarsus length equals breadth, ventrally one short spine and 2 setae; propodus relatively slender, distinctly curved, without apparent heel; 3 spines on proximal third of sole, distally with about 5 small spines; main claw moderately curved, 1/2 length of propodus; auxiliaries feebly curved, 1/4 length of propodus.

Measurements: Trunk length 0.6; width across 2 nd crurigers 0.68; length of abdomen 0.25; proboscis 0.44. Leg 3: coxa 1—0.25; coxa 2—0.3; coxa 3—0.3; femur 0.75; tibia 1—0.82; tibia 2—0.82; tarsus 0.14; propodus 0.64; main claw 0.31; auxiliary 0.16.

Female: In habitus very similar to male, tubercles on coxae 1 of all legs distinctly less developed, the postero-lateral mostly absent. Oviger shorter and slenderer than in male, 4th and 5 th article shortened; the 4 distal articles each with a pair of spines.

Remarks: T. hummelincki is distinguished from its congeners by the following combination of characters: robust proboscis; the relatively long cheliphores and their spination; the armature of coxae 1; a short abdomen; the distal tubercle on the 7 th oviger article and the shape of the propodus (Stock 1954a: 122). Contrary to the original description the third and fourth palp articles in the Colombian material are distinctly separated.

Close relations to other species in the genus are not apparent. T. isthmiacum shows many common characters, but is easily differentiated by its distally more slender proboscis.

In the study area T. hummelincki is the only species in its genus living in the epifauna and epiphytes of harbour piles, and only occurred there. It seems indifferent to conditions of lighting, as it was encountered as much in conditions exposed to light as in shaded jetty areas. Ovigerous males were encountered in the months II and VI, in females ova were recognizable in IV–V and X.

Distribution: T. hummelincki was known by its holotype (male) from Los Frailes in Venezuela only

Figures

FIGURE 20. Tanystylum hummelincki Stock, 1954: A male dorsal, B male lateral, C female dorsal, D male palp, E female oviger, F male oviger.

FIGURE 21. Tanystylum hummelincki Stock, 1954: A male leg 3, B cement gland duct on leg 3, C female leg 3.