Endeis difficilis, Müller & Krapp, 2009

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 : 116-117

Endeis difficilis n.sp.

Fig. 61

Material: Holotype: 43.—Male (ov.) ( SMF 1533 ), Thalassia , 1–1.5 m, 25.II.1986.

Paratypes: 43.— 4 males, 2 fem., 4 juv. ( SMF 1692 ), together with holotype .

Etymology: The species epithet refers to the difficulties in separating the often very similar species in this genus, which needs a revision urgently.

Description of male holotype: Trunk relatively robust, in dorsal outline oval, all segments separate. Crurigers smooth, just longer than broad, separated by slightly less than 1.5 times their own diameter, with one dorsodistal seta. First trunk segment above origin of proboscis with two flat outgrowths. Ocular process about as high as basal diameter, bearing a small distal lappet, eyes small and distinctly pigmented. Abdomen very short, hardly longer than ocular process, nearly upright and distally rounded; bearing 2–4 short setae in its distal quarter. Proboscis subcylindrical, longer than first two trunk segments; slightly broadened at end of proximal third; distal third densely clad with small setae and continually narrowing, distally rounded.

Oviger rather robust, 7-articled; 2 nd article the longest, 1.4 times as long as 4 th; 5 th article as long as 4 th, but significantly more strongly curved; 6 th article robust, in its proximal half with a small lateral tubercle which bears two short setae; 7 th article 2/3 length of 6 th; terminal article with small tubercle with a short seta on inner margin at half length, and 3 short distal setae.

Legs fairly robust, sparsely setose, with exception of tibia 2, tarsus and propodus; coxa 1 about 2/5 length of coxa 3, bearing 1–2 short dorso-distal setae; coxa 2 nearly as long as coxae 1 and 3 together; femur the most robust and longest article, with 3 short slender dorso-distal spines; one row of 17 cement gland pores on lateral aspect, along almost entire length of femur; tibia 2 1.2 times as long as tibia 1; tarsus as long as its diameter, ventrally with some setae and longer spine; propodus feebly curved, flat heel in proximal third bearing 4 robust long spines; sole almost straight, with 5 short robust spines; main claw scarcely curved, half length of propodus; auxiliary claw more curved and slenderer than main claw, about 3/5 length of main claw.

Colouration in ethanol a light yellowish-green.

Measurements: Trunk length 2.63; width 1.29 (across first crurigers); length of abdomen 0.38; length of proboscis 1.63; length of articles of leg 3: coxa 1—0.33; coxa 2—1.02; femur 2.81; tibia 1, 2.27; tibia 2, 2.65; tarsus 0.26; propodus 1.15; main claw 0.58; auxiliary claw 0.41.

Female: like male apart of the sex-specific characters.

Remarks: In the research area Endeis mollis is the most similar species to E. difficilis , from which it is distinguished by its smaller size and a distinctly more robust habitus, including the legs. In combination with this, the crurigers of E. difficilis are separated by slightly less than 1.5 times their diameter, in E. mollis by at least the double their diameter. Both species possess femora which show relatively parallel side walls with a similar number of cement gland pores, which are arranged in a single row along the entire length of that article. The proboscis in E. difficilis is more densely clad with setae in its distal third, and in this region is distinctly narrower than in E. mollis (cf. Fig. 62 ). Even though this difficult genus is in severe need of a revision the description of a new species seems warranted by the afore-mentioned characters. In its rather robust habitus E. difficilis resembles most Endeis flaccida Calman, 1923 from the western Atlantic, which possesses crurigers closer together (distance between crurigers 1 and 2 less than diameter of article) combined with a substantially higher number of cement gland pores. In the original description (Calman 1923: 295, Fig. 17 ) about 57 pores cover almost the entire dorso-lateral surface of the femur in an irregular strip.

In the research area E. difficilis was found only once in seagrass stands in the east of the Tayrona National Park.

Distribution: Caribbean coast of Colombia.

Figures

FIGURE 17. Tanystylum acuminatum Stock, 1954: A male dorsal, B female dorsal, C male lateral, D proboscis ventral, E palp, F male oviger, G distal article of male oviger, H male leg 3, I cement gland duct of male leg 3, J female leg 3.

FIGURE 61. Endeis difficilis n. sp., male: A trunk lateral with oviger, B trunk dorsal, C oviger, D leg 3, E propodus and tarsus.

FIGURE 62. Endeis mollis (Carpenter, 1904), male: A trunk lateral with oviger, B trunk dorsal, C oviger, D leg 3, E propodus and tarsus of leg 3.